1
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Wong FSY, Tsang KK, Chan BP, Lo ACY. Both non-coated and polyelectrolytically-coated intraocular collagen-alginate composite gels enhanced photoreceptor survival in retinal degeneration. Biomaterials 2023; 293:121948. [PMID: 36516686 DOI: 10.1016/j.biomaterials.2022.121948] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 11/09/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022]
Abstract
Treatments of vision-threatening retinal diseases are often hampered by drug delivery difficulties. Polyelectrolytically-coated alginate encapsulated-cell therapy (ECT) systems have shown therapeutic efficacy through prolonged in vivo drug delivery but still face various biocompatibility, viability, drug delivery and mechanical stability issues in clinical trials. Here, novel, injectable alginate-poly-l-lysine (AP)-coated composite alginate-collagen (CAC) ECT gels were developed for sustained ocular drug delivery, and their long-term performance was compared with non-coated CAC ECT gels. All optimised AP-coated gels (AP1- and AP5.5-CAC ECT: 2 mg/ml collagen, 1.5% high molecular weight alginate, 50,000 cells/gel, with 0.01% or 0.05% poly-l-lysine coating for 5 min, followed by 0.15% alginate coating) and non-coated gels showed effective cell proliferation control, cell viability support and continuous delivery of bioactive glial cell-derived neurotrophic factor (GDNF) with no significant gel degradation in vitro and in rat vitreous. Most importantly, intravitreally injected gels demonstrated therapeutic efficacy in Royal College of Surgeons rats with retinal degeneration, resulting in reduced photoreceptor apoptosis and retinal function loss. At 6 months post-implantation, no host-tissue attachment or ingrowth was detected on the retrieved gels. Non-coated gels were mechanically more stable than AP5.5-coated ones under the current cell loading. This study demonstrated that both coated and non-coated ECT gels can serve as well-controlled, sustained drug delivery platforms for treating posterior eye diseases without immunosuppression.
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Affiliation(s)
- Francisca Siu Yin Wong
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
| | - Ken Kin Tsang
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Barbara Pui Chan
- Tissue Engineering Laboratory, Department of Mechanical Engineering, Faculty of Engineering, The University of Hong Kong, Hong Kong, China
| | - Amy Cheuk Yin Lo
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
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2
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Yang XX, Yip CH, Zhao S, Ho YP, Chan BP. A bio-inspired nano-material recapitulating the composition, ultra-structure, and function of the glycosaminoglycan-rich extracellular matrix of nucleus pulposus. Biomaterials 2023; 293:121991. [PMID: 36586145 DOI: 10.1016/j.biomaterials.2022.121991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 12/22/2022] [Accepted: 12/24/2022] [Indexed: 12/28/2022]
Abstract
The nucleus pulposus (NP) of intervertebral disc represents a soft gel consisting of glycosaminoglycans (GAGs)-rich extracellular matrix (ECM). Significant loss of GAGs and normal functions are the most prevalent changes in degenerated disc. Attempts targeted to incorporate GAGs into collagen fibrous matrices have been made but the efficiency is very low, and the resulting structures showed no similarity with native NP. Inspired by the characteristic composition and structures of the ECM of native NP, here, we hypothesize that by chemically modifying the collagen (Col) and hyaluronic acid (HA) and co-precipitating with GAGs, a bio-inspired nano-material recapitulating the composition, ultra-structure and function of the GAG-rich ECM will be fabricated. Compositionally, the bio-inspired nano-material namely Aminated Collagen-Aminated Hyaluronic Acid-GAG (aCol-aHA-GAG) shows a record high GAG/hydroxyproline ratio up to 39.1:1 in a controllable manner, out-performing that of the native NP. Ultra-structurally, the nano-material recapitulates the characteristic 'nano-beads' (25 nm) and 'bottle-brushes' (133 nm) features as those found in native NP. Functionally, the nano-material supports the viability and maintains the morphological and phenotypic markers of bovine NP cells, and shows comparable mechanical properties of native NP. This work contributes to the development of a compositionally, structurally, and functionally biomimetic nano-material for NP tissue engineering.
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Affiliation(s)
- Xing-Xing Yang
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region
| | - Chi-Hung Yip
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region
| | - Shirui Zhao
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong Special Administrative Region
| | - Yi-Ping Ho
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong Special Administrative Region
| | - Barbara Pui Chan
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
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3
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Cheng HW, Chik TK, Weir JW, Chan BP. Differentiation of Equine Mesenchymal Stem Cells into Cells of Osteochondral Lineage: Potential for Osteochondral Tissue Engineering. Biomed Mater 2022; 17. [PMID: 36001983 DOI: 10.1088/1748-605x/ac8c76] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 08/24/2022] [Indexed: 11/11/2022]
Abstract
Damage to the hyaline cartilage of the joint surface and osteochondral fractures are key factors leading to the development of osteoarthritis in racehorses, representing a significant cause of racehorse retirement. To tissue-engineer an osteochondral unit that is suitable for joint repair, incorporation of a zone of calcified cartilage should be considered so as to mimic its in vivo counterpart. To date, equine mesenchymal stem cells (eMSCs) have been reported to have multilineage differentiation potential. Yet the generation of a zone of calcified cartilage using eMSCs has not been reported. This work is an initial attempt to generate a zone of calcified cartilage using eMSCs as the single source of cells and collagen as the scaffolding material. Main advantages of using eMSCs over equine deep zone chondrocytes for the generation of a zone of calcified cartilage include no donor site morbidity and their ease of expansion in culture. Initially, we fabricated cartilage-like tissues and bone-like tissues in vitro by differentiating eMSCs towards chondrogenic and osteogenic lineages for 21 days, respectively. We then aggregated the cartilage-like and bone-like tissues together with a layer of undifferentiated eMSCs-collagen gel in between to generate a 3-layer osteochondral unit. A zone of calcified cartilage was found between the cartilage-like and bone-like layers after a 14-day culture in chondrogenic differentiation medium. These results provide a solution towards tissue engineering of equine osteochondral units with interfacial zone without using chondrocytes harvested from the deep zone of healthy articular cartilage, and contribute to the future development of osteochondral tissue engineering strategies for human cartilage injuries in the long run.
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Affiliation(s)
- H W Cheng
- Tissue Engineering Lab, Mechanical Engineering, The University of Hong Kong Faculty of Engineering, Pokfulam Road, Hong Kong, 00000, HONG KONG
| | - T K Chik
- Tissue Engineering Lab, Mechanical Engineering, The University of Hong Kong Faculty of Engineering, Pokfulam Road, Hong Kong, 00000, HONG KONG
| | - J W Weir
- The Hong Kong Jockey Club, Sha Tin Racecourse, Shatin, Hong Kong, 00000, HONG KONG
| | - B P Chan
- Tissue Engineering Lab, Mechanical Engineering, The University of Hong Kong Faculty of Engineering, Room 711, Haking Wong Building, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong, 00000, CHINA
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4
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Chen M, Hu S, Zhou Z, Huang N, Lee S, Zhang Y, Cheng R, Yang J, Xu Z, Liu Y, Lee H, Huan X, Feng SP, Shum HC, Chan BP, Seol SK, Pyo J, Tae Kim J. Three-Dimensional Perovskite Nanopixels for Ultrahigh-Resolution Color Displays and Multilevel Anticounterfeiting. Nano Lett 2021; 21:5186-5194. [PMID: 34125558 DOI: 10.1021/acs.nanolett.1c01261] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Hybrid perovskites are emerging as a promising, high-performance luminescent material; however, the technological challenges associated with generating high-resolution, free-form perovskite structures remain unresolved, limiting innovation in optoelectronic devices. Here, we report nanoscale three-dimensional (3D) printing of colored perovskite pixels with programmed dimensions, placements, and emission characteristics. Notably, a meniscus comprising femtoliters of ink is used to guide a highly confined, out-of-plane crystallization process, which generates 3D red, green, and blue (RGB) perovskite nanopixels with ultrahigh integration density. We show that the 3D form of these nanopixels enhances their emission brightness without sacrificing their lateral resolution, thereby enabling the fabrication of high-resolution displays with improved brightness. Furthermore, 3D pixels can store and encode additional information into their vertical heights, providing multilevel security against counterfeiting. The proof-of-concept experiments demonstrate the potential of 3D printing to become a platform for the manufacture of smart, high-performance photonic devices without design restrictions.
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Affiliation(s)
- Mojun Chen
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Shiqi Hu
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Zhiwen Zhou
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Nan Huang
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Sanghyeon Lee
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Yage Zhang
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Rui Cheng
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Jihyuk Yang
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Zhaoyi Xu
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Yu Liu
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Heekwon Lee
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Xiao Huan
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Shien-Ping Feng
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Ho Cheung Shum
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Barbara Pui Chan
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Seung Kwon Seol
- Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute (KERI), Changwon-si, Gyeongsangnam-do 51543, Republic of Korea
- Electrical-Functionality Materials Engineering, Korea University of Science and Technology (UST), Changwon-si, Gyeongsangnam-do 51543, Republic of Korea
| | - Jaeyeon Pyo
- Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute (KERI), Changwon-si, Gyeongsangnam-do 51543, Republic of Korea
| | - Ji Tae Kim
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
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5
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Lim Lam VK, Hin Wong JY, Chew SY, Chan BP. Rac1-GTPase regulates compression-induced actin protrusions (CAPs) of mesenchymal stem cells in 3D collagen micro-tissues. Biomaterials 2021; 274:120829. [PMID: 33933985 DOI: 10.1016/j.biomaterials.2021.120829] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 04/13/2021] [Accepted: 04/13/2021] [Indexed: 01/19/2023]
Abstract
Cells can sense mechanical signals through cytoskeleton reorganization. We previously discovered the formation of omni-directional actin protrusions upon compression loading, namely compression-induced actin protrusions (CAPs), in human mesenchymal stem cells (MSCs) in 3D micro-tissues. Here, the regulatory roles of three RhoGTPases (CDC42, Rac1 and RhoA) in the formation of CAPs were investigated. Upon compression loading, extensive formation of CAPs was found, significantly associated with an upregulated mRNA expression of Rac1 only, but not CDC42, nor RhoA. Upon chemical inhibition of these RhoGTPase activity during compression, only Rac1 activity was significantly suppressed, associating with the reduced CAP formation. Silencing the upstream regulators of these RhoGTPase pathways including Rac1 by specific siRNA dramatically disrupted actin cytoskeleton, distorted cell morphology and aborted CAP formation. Silencing cortactin (CTTN), a downstream effector of the Rac1 pathway, induced a compensatory upregulation of Rac1, enabling the MSCs to respond to the compression loading stimulus in terms of CAP formation, although at a reduced number. The importance of Rac1 signalling in CAP formation and the corresponding upregulation of lamellipodial markers also suggest that these CAPs are lamellipodia in nature. This study delineates the mechanism of compression-induced cytoskeleton reorganization, contributing to rationalizing mechanical loading regimes for functional tissue engineering.
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Affiliation(s)
- Vincent Kwok Lim Lam
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
| | - Johnny Yu Hin Wong
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
| | - Sing Yian Chew
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, 637459, Singapore
| | - Barbara Pui Chan
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China.
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6
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Li CW, Lau YT, Lam KL, Chan BP. Mechanically induced formation and maturation of 3D-matrix adhesions (3DMAs) in human mesenchymal stem cells. Biomaterials 2020; 258:120292. [DOI: 10.1016/j.biomaterials.2020.120292] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 06/15/2020] [Accepted: 08/01/2020] [Indexed: 11/26/2022]
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7
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Chen M, Lee H, Yang J, Xu Z, Huang N, Chan BP, Kim JT. Parallel, Multi-Material Electrohydrodynamic 3D Nanoprinting. Small 2020; 16:e1906402. [PMID: 32101385 DOI: 10.1002/smll.201906402] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/19/2019] [Indexed: 06/10/2023]
Abstract
Direct mass-transfer via liquid nanodroplets is one of the most powerful approaches for additive micro/nanofabrication. Electrohydrodynamic (EHD) dispensing has made the delivery of nanosized droplets containing diverse materials a practical reality; however, in its serial form it has insufficient throughput for large-area processing. Here, a parallel, nanoscale EHD method is developed that offers both improved productivity and material diversity in 3D nanoprinting. The method exploits a double-barreled glass nanopipette filled with material inks to parallelize nanodripping ejections, enabling a dual 3D nanoprinting process. It is discovered that an unusual electric field distribution created by cross talk of neighboring pipette apertures can be used to steer the microscopic ejection paths of the ink at will, enabling on-demand control over shape, placement, and material mixing in 3D printed nanostructures. After thorough characterizations of the printing conditions, the parallel fabrication of nanomeshes and nanowalls of silver, CdSe/ZnS quantum dots, and their composites, with programmed designs is demonstrated. This method is expected to advance productivity in the heterogeneous integration of functional 3D nanodevices in a facile manner.
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Affiliation(s)
- Mojun Chen
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Heekwon Lee
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Jihyuk Yang
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Zhaoyi Xu
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Nan Huang
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Barbara Pui Chan
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Ji Tae Kim
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
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8
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Abstract
Extracellular matrix (ECM) provides both physical support and bioactive signals such as growth factors and cytokines to cells at their microenvironment or niche. Engineering the matrix niche becomes an important approach to study or manipulate cellular fate. This work presents an overview on the reconstitution of the ECM niche through a wide range of approaches ranging from coating culture dish with ECM molecules to decellularization of native tissues. In particular, we focused on reconstituting the complex ECM niche through cell-derived matrix (CDM) by reviewing the methodological approaches used in our group to derive ECM from mature cells such as chondrocytes and nucleus pulposus cells (NPCs), undifferentiated stem cells such as mesenchymal stem cells (MSCs), as well as MSCs undergoing chondrogenic and osteogenic differentiation, in 2D or 3D models. Specific attention has also been given to key factors that should be considered in various applications and challenges in relation to the CDM. Last but not the least, a few future perspectives and their significance have been proposed.
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Affiliation(s)
- H W Cheng
- Tissue Engineering Laboratory, Biomedical Engineering Programme, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong
| | - M T Yuan
- Tissue Engineering Laboratory, Biomedical Engineering Programme, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong
| | - C W Li
- Tissue Engineering Laboratory, Biomedical Engineering Programme, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong
| | - B P Chan
- Tissue Engineering Laboratory, Biomedical Engineering Programme, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong.
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9
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Li YY, Lam KL, Chen AD, Zhang W, Chan BP. Collagen microencapsulation recapitulates mesenchymal condensation and potentiates chondrogenesis of human mesenchymal stem cells – A matrix-driven in vitro model of early skeletogenesis. Biomaterials 2019; 213:119210. [DOI: 10.1016/j.biomaterials.2019.05.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 04/28/2019] [Accepted: 05/10/2019] [Indexed: 01/01/2023]
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10
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Huang N, Li CW, Chan BP. Multiphoton 3D Microprinting of Protein Micropatterns with Spatially Controlled Heterogeneity - A Platform for Single Cell Matrix Niche Studies. ACTA ACUST UNITED AC 2018. [DOI: 10.1002/adbi.201800053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Nan Huang
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Chuen Wai Li
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Barbara Pui Chan
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
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11
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Jiang S, Li SC, Huang C, Chan BP, Du Y. Physical Properties of Implanted Porous Bioscaffolds Regulate Skin Repair: Focusing on Mechanical and Structural Features. Adv Healthc Mater 2018; 7:e1700894. [PMID: 29334185 DOI: 10.1002/adhm.201700894] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/23/2017] [Indexed: 01/07/2023]
Abstract
Porous bioscaffolds are applied to facilitate skin repair since the early 1990s, but a perfect regeneration outcome has yet to be achieved. Until now, most efforts have focused on modulating the chemical properties of bioscaffolds, while physical properties are traditionally overlooked. Recent advances in mechanobiology and mechanotherapy have highlighted the importance of biomaterials' physical properties in the regulation of cellular behaviors and regenerative processes. In skin repair, the mechanical and structural features of porous bioscaffolds are two major physical properties that determine therapeutic efficacy. Here, first an overview of natural skin repair with an emphasis on the major biophysically sensitive cell types involved in this multistage process is provided, followed by an introduction of the four roles of bioscaffolds as skin implants. Then, how the mechanical and structural features of bioscaffolds influence these four roles is discussed. The mechanical and structural features of porous bioscaffolds should be tailored to balance the acceleration of wound closure and functional improvements of the repaired skin. This study emphasizes that decoupling and precise control of the mechanical and structural features of bioscaffolds are significant aspects that should be considered in future biomaterial optimization, which can build a foundation to ultimately achieve perfect skin regeneration outcomes.
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Affiliation(s)
- Shumeng Jiang
- Department of Biomedical Engineering School of Medicine Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases MOE Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology Tsinghua University Beijing 100084 China
| | - Sabrina Cloud Li
- Department of Biomedical Engineering School of Medicine Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases MOE Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology Tsinghua University Beijing 100084 China
| | - Chenyu Huang
- Beijing Tsinghua Changgung Hospital Tsinghua University Beijing 102218 China
| | - Barbara Pui Chan
- Tissue Engineering Laboratory Department of Mechanical Engineering The University of Hong Kong Hong Kong Special Administrative Region China
| | - Yanan Du
- Department of Biomedical Engineering School of Medicine Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases MOE Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology Tsinghua University Beijing 100084 China
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12
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Chan BP, Khan K. A230 DRESS: AN UNUSUAL CASE OF UPPER GASTROINTESTINAL BLEED. J Can Assoc Gastroenterol 2018. [DOI: 10.1093/jcag/gwy008.231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- B P Chan
- Gastroenterology, McMaster University, Hamilton, ON, Canada
| | - K Khan
- McMaster University, Hamilton, ON, Canada
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13
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Affiliation(s)
- B P Chan
- Gastroenterology, McMaster University, Hamilton, ON, Canada
| | - M Fine
- Gastroenterology, McMaster University, Hamilton, ON, Canada
| | - S Shaffer
- University of Manitoba, Winnipeg, MB, Canada
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14
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Daly ER, Fredette C, Mathewson AA, Dufault K, Swenson DJ, Chan BP. Tick bite and Lyme disease-related emergency department encounters in New Hampshire, 2010-2014. Zoonoses Public Health 2017; 64:655-661. [PMID: 28432738 DOI: 10.1111/zph.12361] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Indexed: 11/28/2022]
Abstract
Lyme disease (LD) is a common tick-borne disease in New Hampshire (NH). While LD is a reportable condition and cases are counted for public health surveillance, many more people receive care for tick bites or diagnoses of LD than are reflected in surveillance data. NH's emergency department (ED) data system was queried for tick bite and LD-related encounters. Chief complaint text was queried for words related to LD or tick bites. International Classification of Diseases 9th Revision (ICD-9) codes were queried for the LD diagnosis code (088.81). Emergency department patient data were matched to reportable disease data to determine the proportion of ED patients reported to the health department as a suspected LD case. Data were analysed to calculate frequencies for key demographic and reporting characteristics. From 2010 to 2014, 13,615 tick bite or LD-related ED encounters were identified in NH, with most due to tick bites (76%). Of 3,256 patients with a LD-related ED encounter, 738 (23%) were reported to the health department as a suspected LD case. The geographic distribution of ED patients was similar to reported LD cases; however, the regions of the state that experienced higher rates of ED encounters were different than the regions that observed higher rates of reported LD cases. Seasonal distribution of ED encounters peaked earlier than reported LD cases with a second peak in the fall. While age and sex distribution was similar among ED patients and reported LD cases, the rates for children 5 years and younger and adults 65 years and older were greater for ED encounters. Patients frequently visit the ED to seek care for tick bites and suspected LD. Results of ED data analyses can be used to target education, in particular for ED providers and the public through timely distribution of evidence-based educational materials and training programmes.
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Affiliation(s)
- E R Daly
- New Hampshire Department of Health and Human Services, Concord, NH, USA
| | - C Fredette
- New Hampshire Department of Health and Human Services, Concord, NH, USA
| | - A A Mathewson
- New Hampshire Department of Health and Human Services, Concord, NH, USA
| | - K Dufault
- New Hampshire Department of Health and Human Services, Concord, NH, USA
| | - D J Swenson
- New Hampshire Department of Health and Human Services, Concord, NH, USA
| | - B P Chan
- New Hampshire Department of Health and Human Services, Concord, NH, USA
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15
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Diao HJ, Fung HS, Yeung P, Lam K, Yan CH, Chan BP. Dynamic cyclic compression modulates the chondrogenic phenotype in human chondrocytes from late stage osteoarthritis. Biochem Biophys Res Commun 2017; 486:14-21. [DOI: 10.1016/j.bbrc.2017.02.073] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 02/13/2017] [Indexed: 11/24/2022]
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16
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Fan X, Zhu L, Wang K, Wang B, Wu Y, Xie W, Huang C, Chan BP, Du Y. Stiffness-Controlled Thermoresponsive Hydrogels for Cell Harvesting with Sustained Mechanical Memory. Adv Healthc Mater 2017; 6. [PMID: 28105774 DOI: 10.1002/adhm.201601152] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 11/23/2016] [Indexed: 01/17/2023]
Abstract
Most mechanobiological investigations focused on in situ mechanical regulation of cells on stiffness-controlled substrates with few downstream applications, as it is still challenging to harvest and expand mechanically primed cells by enzymatic digestion (e.g., trypsin) without interrupting cellular mechanical memory between passages. This study develops thermoresponsive hydrogels with controllable stiffness to generate mechanically primed cells with intact mechanical memory for augmented wound healing. No significant cellular property alteration of the fibroblasts primed on thermoresponsive hydrogels with varied stiffness has been observed through thermoresponsive harvesting. When reseeding the harvested cells for further evaluation, softer hydrogels are proven to better sustain the mechanical priming effects compared to rigid tissue culture plate, which indicates that both the stiffness-controlled substrate and thermoresponsive harvesting are required to sustain cellular mechanical memory between passages. Moreover, epigenetics analysis reveals that thermoresponsive harvesting could reduce the rearrangement and loss of chromatin proteins compared to that of trypsinization. In vivo wound healing using mechanically primed fibroblasts shows featured epithelium and sebaceous glands, which indicates augmented skin recovery compared with trypsinized fibroblasts. Thus, the thermoresponsive hydrogel-based cell harvesting system offers a powerful tool to investigate mechanobiology between cell passages and produces abundant cells with tailored mechanical priming properties for cell-based applications.
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Affiliation(s)
- Xingliang Fan
- Department of Biomedical Engineering; School of Medicine; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases; Tsinghua University; Beijing 100084 China
- Joint Center for Life Sciences; Tsinghua University-Peking University; Beijing 100084 China
| | - Lu Zhu
- Department of Biomedical Engineering; School of Medicine; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases; Tsinghua University; Beijing 100084 China
- Institute of Medical Equipment; Academy of Military Medical Sciences; Tianjin 300161 China
| | - Ke Wang
- Department of Chemistry; School of Science; Tsinghua University; Beijing 100084 China
| | - Bingjie Wang
- Department of Biomedical Engineering; School of Medicine; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases; Tsinghua University; Beijing 100084 China
- School of Life Science; Tsinghua University; Beijing 100084 China
| | - Yaozu Wu
- Department of Biomedical Engineering; School of Medicine; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases; Tsinghua University; Beijing 100084 China
| | - Wei Xie
- Joint Center for Life Sciences; Tsinghua University-Peking University; Beijing 100084 China
- School of Life Science; Tsinghua University; Beijing 100084 China
| | - Chengyu Huang
- Department of Plastic; Reconstructive and Aesthetic Surgery; Beijing Tsinghua Changgung Hospital; Tsinghua University; Beijing 102218 China
| | - Barbara Pui Chan
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Yanan Du
- Department of Biomedical Engineering; School of Medicine; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases; Tsinghua University; Beijing 100084 China
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Zhou ZL, Ma J, Tong MH, Chan BP, Wong AST, Ngan AHW. Nanomechanical measurement of adhesion and migration of leukemia cells with phorbol 12-myristate 13-acetate treatment. Int J Nanomedicine 2016; 11:6533-6545. [PMID: 27994457 PMCID: PMC5153271 DOI: 10.2147/ijn.s118065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
The adhesion and traction behavior of leukemia cells in their microenvironment is directly linked to their migration, which is a prime issue affecting the release of cancer cells from the bone marrow and hence metastasis. In assessing the effectiveness of phorbol 12-myristate 13-acetate (PMA) treatment, the conventional batch-cell transwell-migration assay may not indicate the intrinsic effect of the treatment on migration, since the treatment may also affect other cellular behavior, such as proliferation or death. In this study, the pN-level adhesion and traction forces between single leukemia cells and their microenvironment were directly measured using optical tweezers and traction-force microscopy. The effects of PMA on K562 and THP1 leukemia cells were studied, and the results showed that PMA treatment significantly increased cell adhesion with extracellular matrix proteins, bone marrow stromal cells, and human fibroblasts. PMA treatment also significantly increased the traction of THP1 cells on bovine serum albumin proteins, although the effect on K562 cells was insignificant. Western blots showed an increased expression of E-cadherin and vimentin proteins after the leukemia cells were treated with PMA. The study suggests that PMA upregulates adhesion and thus suppresses the migration of both K562 and THP1 cells in their microenvironment. The ability of optical tweezers and traction-force microscopy to measure directly pN-level cell–protein or cell–cell contact was also demonstrated.
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Affiliation(s)
| | - Jing Ma
- School of Biological Sciences, University of Hong Kong, Hong Kong, People's Republic of China
| | | | | | - Alice Sze Tsai Wong
- School of Biological Sciences, University of Hong Kong, Hong Kong, People's Republic of China
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Chooi WH, Chan SCW, Gantenbein B, Chan BP. Correction: Loading-Induced Heat-Shock Response in Bovine Intervertebral Disc Organ Culture. PLoS One 2016; 11:e0167406. [PMID: 27875587 PMCID: PMC5119852 DOI: 10.1371/journal.pone.0167406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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19
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Chooi WH, Chan SCW, Gantenbein B, Chan BP. Loading-Induced Heat-Shock Response in Bovine Intervertebral Disc Organ Culture. PLoS One 2016; 11:e0161615. [PMID: 27580124 PMCID: PMC5006975 DOI: 10.1371/journal.pone.0161615] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 08/09/2016] [Indexed: 12/22/2022] Open
Abstract
Mechanical loading has been shown to affect cell viability and matrix maintenance in the intervertebral disc (IVD) but there is no investigation on how cells survive mechanical stress and whether the IVD cells perceive mechanical loading as stress and respond by expression of heat shock proteins. This study investigates the stress response in the IVD in response to compressive loading. Bovine caudal disc organ culture was used to study the effect of physiological range static loading and dynamic loading. Cell activity, gene expression and immunofluorescence staining were used to analyze the cell response. Cell activity and cytoskeleton of the cells did not change significantly after loading. In gene expression analysis, significant up-regulation of heat shock protein-70 (HSP70) was observed in nucleus pulposus after two hours of loading. However, the expression of the matrix remodeling genes did not change significantly after loading. Similarly, expressions of stress response and matrix remodeling genes changed with application and removal of the dynamic loading. The results suggest that stress response was induced by physiological range loading without significantly changing cell activity and upregulating matrix remodeling. This study provides direct evidence on loading induced stress response in IVD cells and contributes to our understanding in the mechanoregulation of intervertebral disc cells.
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Affiliation(s)
- Wai Hon Chooi
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Samantha Chun Wai Chan
- Tissue & Organ Mechanobiology, Institute of Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland.,Biointerfaces, Empa, Swiss Federal Laboratories for Materials Science and Technology, St Gallen, Switzerland
| | - Benjamin Gantenbein
- Tissue & Organ Mechanobiology, Institute of Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland
| | - Barbara Pui Chan
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China
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Chooi WH, Chan BP. Compression loading-induced stress responses in intervertebral disc cells encapsulated in 3D collagen constructs. Sci Rep 2016; 6:26449. [PMID: 27197886 PMCID: PMC4873809 DOI: 10.1038/srep26449] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 04/29/2016] [Indexed: 01/24/2023] Open
Abstract
Cells protect themselves from stresses through a cellular stress response. In the interverebral disc, such response was also demonstrated to be induced by various environmental stresses. However, whether compression loading will cause cellular stress response in the nucleus pulposus cells (NPCs) is not well studied. By using an in vitro collagen microencapsulation model, we investigated the effect of compression loading on the stress response of NPCs. Cell viability tests, and gene and protein expression experiments were conducted, with primers for the heat shock response (HSR: HSP70, HSF1, HSP27 and HSP90), and unfolded protein response (UPR: GRP78, GRP94, ATF4 and CHOP) genes and an antibody to HSP72. Different gene expression patterns occurred due to loading type throughout experiments. Increasing the loading strain for a short duration did not increase the stress response genes significantly, but over longer durations, HSP70 and HSP27 were upregulated. Longer loading durations also resulted in a continuous upregulation of HSR genes and downregulation of UPR genes, even after load removal. The rate of apoptosis did not increase significantly after loading, suggesting that stress response genes might play a role in cell survival following mechanical stress. These results demonstrate how mechanical stress might induce and control the expression of HSR and UPR genes in NPCs.
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Affiliation(s)
- Wai Hon Chooi
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
| | - Barbara Pui Chan
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
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21
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Han S, Li YY, Chan BP. Extracellular Protease Inhibition Alters the Phenotype of Chondrogenically Differentiating Human Mesenchymal Stem Cells (MSCs) in 3D Collagen Microspheres. PLoS One 2016; 11:e0146928. [PMID: 26760956 PMCID: PMC4711899 DOI: 10.1371/journal.pone.0146928] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 12/22/2015] [Indexed: 11/18/2022] Open
Abstract
Matrix remodeling of cells is highly regulated by proteases and their inhibitors. Nevertheless, how would the chondrogenesis of mesenchymal stem cells (MSCs) be affected, when the balance of the matrix remodeling is disturbed by inhibiting matrix proteases, is incompletely known. Using a previously developed collagen microencapsulation platform, we investigated whether exposing chondrogenically differentiating MSCs to intracellular and extracellular protease inhibitors will affect the extracellular matrix remodeling and hence the outcomes of chondrogenesis. Results showed that inhibition of matrix proteases particularly the extracellular ones favors the phenotype of fibrocartilage rather than hyaline cartilage in chondrogenically differentiating hMSCs by upregulating type I collagen protein deposition and type II collagen gene expression without significantly altering the hypertrophic markers at gene level. This study suggests the potential of manipulating extracellular proteases to alter the outcomes of hMSC chondrogenesis, contributing to future development of differentiation protocols for fibrocartilage tissues for intervertebral disc and meniscus tissue engineering.
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Affiliation(s)
- Sejin Han
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
| | - Yuk Yin Li
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
| | - Barbara Pui Chan
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
- * E-mail:
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22
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Yeung P, Sin HS, Chan S, Chan GCF, Chan BP. Microencapsulation of Neuroblastoma Cells and Mesenchymal Stromal Cells in Collagen Microspheres: A 3D Model for Cancer Cell Niche Study. PLoS One 2015; 10:e0144139. [PMID: 26657086 PMCID: PMC4682120 DOI: 10.1371/journal.pone.0144139] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 11/14/2015] [Indexed: 12/18/2022] Open
Abstract
There is a growing trend for researchers to use in vitro 3D models in cancer studies, as they can better recapitulate the complex in vivo situation. And the fact that the progression and development of tumor are closely associated to its stromal microenvironment has been increasingly recognized. The establishment of such tumor supportive niche is vital in understanding tumor progress and metastasis. The mesenchymal origin of many cells residing in the cancer niche provides the rationale to include MSCs in mimicking the niche in neuroblastoma. Here we co-encapsulate and co-culture NBCs and MSCs in a 3D in vitro model and investigate the morphology, growth kinetics and matrix remodeling in the reconstituted stromal environment. Results showed that the incorporation of MSCs in the model lead to accelerated growth of cancer cells as well as recapitulation of at least partially the tumor microenvironment in vivo. The current study therefore demonstrates the feasibility for the collagen microsphere to act as a 3D in vitro cancer model for various topics in cancer studies.
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Affiliation(s)
- Pan Yeung
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
| | - Hoi Shun Sin
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
| | - Shing Chan
- Department of Adolescence Medicine and Paediatrics, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Godfrey Chi Fung Chan
- Department of Adolescence Medicine and Paediatrics, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Barbara Pui Chan
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
- * E-mail:
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Choy ATH, Chan BP. A Structurally and Functionally Biomimetic Biphasic Scaffold for Intervertebral Disc Tissue Engineering. PLoS One 2015; 10:e0131827. [PMID: 26115332 PMCID: PMC4482706 DOI: 10.1371/journal.pone.0131827] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Accepted: 06/05/2015] [Indexed: 11/24/2022] Open
Abstract
Tissue engineering offers high hopes for the treatment of intervertebral disc (IVD) degeneration. Whereas scaffolds of the disc nucleus and annulus have been extensively studied, a truly biomimetic and mechanically functional biphasic scaffold using naturally occurring extracellular matrix is yet to be developed. Here, a biphasic scaffold was fabricated with collagen and glycosaminoglycans (GAGs), two of the most abundant extracellular matrix components in the IVD. Following fabrication, the scaffold was characterized and benchmarked against native disc. The biphasic scaffold was composed of a collagen-GAG co-precipitate making up the nucleus pulposus-like core, and this was encapsulated in multiple lamellae of photochemically crosslinked collagen membranes comprising the annulus fibrosus-like lamellae. On mechanical testing, the height of our engineered disc recovered by ~82-89% in an annulus-independent manner, when compared with the 99% recovery exhibited by native disc. The annulus-independent nature of disc height recovery suggests that the fluid replacement function of the engineered nucleus pulposus core might mimic this hitherto unique feature of native disc. Biphasic scaffolds comprised of 10 annulus fibrosus-like lamellae had the best overall mechanical performance among the various designs owing to their similarity to native disc in most aspects, including elastic compliance during creep and recovery, and viscous compliance during recovery. However, the dynamic mechanical performance (including dynamic stiffness and damping factor) of all the biphasic scaffolds was similar to that of the native discs. This study contributes to the rationalized design and development of a biomimetic and mechanically viable biphasic scaffold for IVD tissue engineering.
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Affiliation(s)
- Andrew Tsz Hang Choy
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Barbara Pui Chan
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China
- * E-mail:
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24
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Ho FC, Zhang W, Li YY, Chan BP. Mechanoresponsive, omni-directional and local matrix-degrading actin protrusions in human mesenchymal stem cells microencapsulated in a 3D collagen matrix. Biomaterials 2015; 53:392-405. [DOI: 10.1016/j.biomaterials.2015.02.102] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 02/22/2015] [Accepted: 02/24/2015] [Indexed: 10/25/2022]
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Chik TK, Chooi WH, Li YY, Ho FC, Cheng HW, Choy TH, Sze KY, Luk KKD, Cheung KMC, Chan BP. Spinal Implants: Bioengineering a Multicomponent Spinal Motion Segment Construct-A 3D Model for Complex Tissue Engineering (Adv. Healthcare Mater. 1/2015). Adv Healthc Mater 2015. [DOI: 10.1002/adhm.201570004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Tsz Kit Chik
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Wai Hon Chooi
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Yuk Yin Li
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Fu Chak Ho
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Hiu Wa Cheng
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Tsz Hang Choy
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Kam Yim Sze
- Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Keith Kei Dip Luk
- Department of Orthopaedics & Traumatology; Li Ka Shing Faculty of Medicine; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Kenneth Man Chi Cheung
- Department of Orthopaedics & Traumatology; Li Ka Shing Faculty of Medicine; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Barbara Pui Chan
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
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Chik TK, Chooi WH, Li YY, Ho FC, Cheng HW, Choy TH, Sze KY, Luk KKD, Cheung KMC, Chan BP. Bioengineering a multicomponent spinal motion segment construct--a 3D model for complex tissue engineering. Adv Healthc Mater 2015; 4:99-112. [PMID: 24846571 DOI: 10.1002/adhm.201400192] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Indexed: 01/28/2023]
Abstract
Intervertebral disc degeneration is an important clinical problem but existing treatments have significant drawbacks. The ability to bioengineer the entire spinal motion segment (SMS) offers hope for better motion preservation strategies but is extremely challenging. Here, fabrication of a multicomponent SMS construct with complex hierarchical organization from mesenchymal stem cells and collagen-based biomaterials, using a module-based integrative approach, is reported. The construct consists of two osteochondral subunits, a nucleus pulposus (NP-)-like core and a multi-lamellae annulus fibrosus (AF-)-like component. Chondrogenic medium is crucial for stabilizing the osteochondral subunits, which are shown to allow passive nutrient diffusion, while cyclic compression is necessary for better fiber matrix organization. Cells adhere, survive, and interact with the NP-like core. Cyclic torsional loading stimulates cell alignment in the AF-like lamellae and the number of lamellae affects the mechanical properties of the construct. This work represents an important milestone in SMS tissue engineering and provides a 3D model for studying tissue maturation and functional remodeling.
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Affiliation(s)
- Tsz Kit Chik
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Wai Hon Chooi
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Yuk Yin Li
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Fu Chak Ho
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Hiu Wa Cheng
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Tsz Hang Choy
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Kam Yim Sze
- Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Keith Kei Dip Luk
- Department of Orthopaedics & Traumatology; Li Ka Shing Faculty of Medicine; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Kenneth Man Chi Cheung
- Department of Orthopaedics & Traumatology; Li Ka Shing Faculty of Medicine; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
| | - Barbara Pui Chan
- Tissue Engineering Laboratory; Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong Special Administrative Region China
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Yeo LLL, Paliwal P, Teoh HL, Seet RC, Chan BP, Ting E, Venketasubramanian N, Leow WK, Wakerley B, Kusama Y, Rathakrishnan R, Sharma VK. Assessment of intracranial collaterals on CT angiography in anterior circulation acute ischemic stroke. AJNR Am J Neuroradiol 2014; 36:289-94. [PMID: 25324493 DOI: 10.3174/ajnr.a4117] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND AND PURPOSE Intracranial collaterals influence the prognosis of patients treated with intravenous tissue plasminogen activator in acute anterior circulation ischemic stroke. We compared the methods of scoring collaterals on pre-tPA brain CT angiography for predicting functional outcomes in acute anterior circulation ischemic stroke. MATERIALS AND METHODS Two hundred consecutive patients with acute anterior circulation ischemic stroke treated with IV-tPA during 2010-2012 were included. Two independent neuroradiologists evaluated intracranial collaterals by using the Miteff system, Maas system, the modified Tan scale, and the Alberta Stroke Program Early CT Score 20-point methodology. Good and extremely poor outcomes at 3 months were defined by modified Rankin Scale scores of 0-1 and 5-6 points, respectively. RESULTS Factors associated with good outcome on univariable analysis were younger age, female sex, hypertension, diabetes mellitus, atrial fibrillation, small infarct core (ASPECTS ≥8), vessel recanalization, lower pre-tPA NIHSS scores, and good collaterals according to Tan methodology, ASPECTS methodology, and Miteff methodology. On multivariable logistic regression, only lower NIHSS scores (OR, 1.186 per point; 95% CI, 1.079-1.302; P = .001), recanalization (OR, 5.599; 95% CI, 1.560-20.010; P = .008), and good collaterals by the Miteff method (OR, 3.341; 95% CI, 1.203-5.099; P = .014) were independent predictors of good outcome. Poor collaterals by the Miteff system (OR, 2.592; 95% CI, 1.113-6.038; P = .027), Maas system (OR, 2.580; 95% CI, 1.075-6.187; P = .034), and ASPECTS method ≤5 points (OR, 2.685; 95% CI, 1.156-6.237; P = .022) were independent predictors of extremely poor outcomes. CONCLUSIONS Only the Miteff scoring system for intracranial collaterals is reliable for predicting favorable outcome in thrombolyzed acute anterior circulation ischemic stroke. However, poor outcomes can be predicted by most of the existing methods of scoring intracranial collaterals.
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Affiliation(s)
- L L L Yeo
- From the Division of Neurology, Department of Medicine (L.L.L.Y., P.P., H.L.T., R.C.S., B.P.C., N.V., B.W., Y.K., R.R., V.K.S.)
| | - P Paliwal
- From the Division of Neurology, Department of Medicine (L.L.L.Y., P.P., H.L.T., R.C.S., B.P.C., N.V., B.W., Y.K., R.R., V.K.S.)
| | - H L Teoh
- From the Division of Neurology, Department of Medicine (L.L.L.Y., P.P., H.L.T., R.C.S., B.P.C., N.V., B.W., Y.K., R.R., V.K.S.)
| | - R C Seet
- From the Division of Neurology, Department of Medicine (L.L.L.Y., P.P., H.L.T., R.C.S., B.P.C., N.V., B.W., Y.K., R.R., V.K.S.) Yong Loo Lin School of Medicine (R.C.S., V.K.S.), National University of Singapore, Singapore
| | - B P Chan
- From the Division of Neurology, Department of Medicine (L.L.L.Y., P.P., H.L.T., R.C.S., B.P.C., N.V., B.W., Y.K., R.R., V.K.S.)
| | - E Ting
- Department of Diagnostic Imaging (E.T.), National University Health System, Singapore
| | - N Venketasubramanian
- From the Division of Neurology, Department of Medicine (L.L.L.Y., P.P., H.L.T., R.C.S., B.P.C., N.V., B.W., Y.K., R.R., V.K.S.)
| | - W K Leow
- Department of Computer Science (W.K.L.)
| | - B Wakerley
- From the Division of Neurology, Department of Medicine (L.L.L.Y., P.P., H.L.T., R.C.S., B.P.C., N.V., B.W., Y.K., R.R., V.K.S.)
| | - Y Kusama
- From the Division of Neurology, Department of Medicine (L.L.L.Y., P.P., H.L.T., R.C.S., B.P.C., N.V., B.W., Y.K., R.R., V.K.S.)
| | - R Rathakrishnan
- From the Division of Neurology, Department of Medicine (L.L.L.Y., P.P., H.L.T., R.C.S., B.P.C., N.V., B.W., Y.K., R.R., V.K.S.)
| | - V K Sharma
- From the Division of Neurology, Department of Medicine (L.L.L.Y., P.P., H.L.T., R.C.S., B.P.C., N.V., B.W., Y.K., R.R., V.K.S.) Yong Loo Lin School of Medicine (R.C.S., V.K.S.), National University of Singapore, Singapore
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Li YY, Diao HJ, Chik TK, Chow CT, An XM, Leung V, Cheung KMC, Chan BP. Delivering mesenchymal stem cells in collagen microsphere carriers to rabbit degenerative disc: reduced risk of osteophyte formation. Tissue Eng Part A 2014; 20:1379-91. [PMID: 24372278 DOI: 10.1089/ten.tea.2013.0498] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Mesenchymal stem cells (MSCs) have the potential to treat early intervertebral disc (IVD) degeneration. However, during intradiscal injection, the vast majority of cells leaked out even in the presence of hydrogel carrier. Recent evidence suggests that annulus puncture is associated with cell leakage and contributes to osteophyte formation, an undesirable side effect. This suggests the significance of developing appropriate carriers for intradiscal delivery of MSCs. We previously developed a collagen microencapsulation platform, which entraps MSCs in a solid microsphere consisting of collagen nanofiber meshwork. These solid yet porous microspheres support MSC attachment, survival, proliferation, migration, differentiation, and matrix remodeling. Here we hypothesize that intradiscal injection of MSCs in collagen microspheres will outperform that of MSCs in saline in terms of better functional outcomes and reduced side effects. Specifically, we induced disc degeneration in rabbits and then intradiscally injected autologous MSCs, either packaged within collagen microspheres or directly suspended in saline, into different disc levels. Functional outcomes including hydration index and disc height were monitored regularly until 6 months. Upon sacrifice, the involved discs were harvested for histological, biochemical, and biomechanical evaluations. MSCs in collagen microspheres showed advantage over MSCs in saline in better maintaining the dynamic mechanical behavior but similar performance in hydration and disc height maintenance and matrix composition. More importantly, upon examination of gross appearance, radiograph, and histology of IVD, delivering MSCs in collagen microspheres significantly reduced the risk of osteophyte formation as compared to that in saline. This work demonstrates the significance of using cell carriers during intradiscal injection of MSCs in treating disc degeneration.
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Affiliation(s)
- Yuk Yin Li
- 1 Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong , Hong Kong, China
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Chik TK, Ma XY, Choy TH, Li YY, Diao HJ, Teng WK, Han SJ, Cheung KMC, Chan BP. Photochemically crosslinked collagen annulus plug: a potential solution solving the leakage problem of cell-based therapies for disc degeneration. Acta Biomater 2013; 9:8128-39. [PMID: 23751592 DOI: 10.1016/j.actbio.2013.05.034] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/25/2013] [Accepted: 05/30/2013] [Indexed: 12/18/2022]
Abstract
Intra-disc injection of mesenchymal stem cells (MSCs) to treat disc degeneration may lead to unfavorable complications, particularly osteophyte formation. Development of an effective method to block the injection portal, prevent the leakage of injected cells and materials and, hence, prevent osteophyte formation is of the utmost importance before MSC-based therapies can be applied in a clinical setting. Here we seek to alleviate the cell leakage problem and the associated complication osteophyte formation by developing an injectable annulus plug to block the injection portal during intra-disc delivery. Specifically, we fabricated a needle-shaped collagen plug by photochemical crosslinking and successfully delivered it intra-discally, in association with MSCs in collagen microsphere carriers, using a custom-made delivery device. The mechanical performance of the plug and its effectiveness in reducing cell leakage were evaluated ex vivo under compression and in torsion push-out tests. The results demonstrate that the plug survived physiologically relevant loadings and significantly reduced leakage and enhanced retention of the injected materials. Finally, a pilot in vivo study in rabbits was conducted to evaluate the performance of the plug. Microcomputed tomography imaging and histology revealed that the plug significantly reduced osteophyte formation. This work suggests the potential of the annulus plug as an adjunct or annulus closure device for intra-disc delivery of cells and materials.
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Affiliation(s)
- T K Chik
- Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region
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Choy ATH, Leong KW, Chan BP. Chemical modification of collagen improves glycosaminoglycan retention of their co-precipitates. Acta Biomater 2013; 9:4661-72. [PMID: 23009864 DOI: 10.1016/j.actbio.2012.09.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 09/10/2012] [Accepted: 09/14/2012] [Indexed: 11/16/2022]
Abstract
Being prevalent extracellular matrix components, collagen and glycosaminoglycan (GAG) are co-precipitated as scaffolds for tissue regeneration. However, the amount of GAG incorporated and its long-term retention present a persistent problem. In this study, chemical modifications, namely deamination, methylation and amination, were used to alter the net charge of collagen prior to fabrication of collagen-GAG co-precipitate. While most GAGs were lost in the untreated group and the deaminated group within 1 day, methylation and amination of collagen retained over 20% and 40% GAG after 6 days, respectively. Moreover, over 60% of GAG retention was achieved in the aminated group after cell seeding for 8 days. Furthermore, amination of collagen increased the GAG/hydroxyproline ratio in the co-precipitate to >4.5, approaching that of native nucleus pulposus. Ultrastructural analysis showed that the aminated group contains abundant granular substances resembling the extracellular matrix of native nucleus pulposus. Despite lower initial cell adhesion than untreated, all modified scaffolds promoted proliferation of human mesenchymal stem cells (hMSCs) and showed >95% cell viability at all time points. Cell morphology was distinct among the different groups, being round in the untreated control and methylated groups but elongated in deaminated and aminated groups. hMSCs adhered to scaffolds via collagen receptor integrin α2β1 in all groups, while all but the aminated group showed extensive expression of the general matrix receptor integrin αv. This work reports an effective method, namely amination of collagen, to improve GAG incorporation and retention in collagen-GAG co-precipitates, facilitating the fabrication of GAG-rich collagenous scaffold for intervertebral disc tissue engineering.
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Affiliation(s)
- A T H Choy
- Department of Mechanical Engineering, University of Hong Kong, Hong Kong Special Administrative Region, China
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Musselman RP, Gomes T, Chan BP, Auer RC, Moloo H, Mamdani M, Al-Omran M, Al-Obeed O, Boushey RP. Changing trends in rectal cancer surgery in Ontario: 2002-2009. Colorectal Dis 2012; 14:1467-72. [PMID: 22487101 DOI: 10.1111/j.1463-1318.2012.03044.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM The safety and efficacy of laparoscopic surgery for colon cancer have been demonstrated in large, multicentre clinical trials. The study aimed to determine the use of laparoscopic surgery for rectal cancer in Ontario over a 7-year period. METHOD We conducted a retrospective study examining rates of elective rectal cancer surgery among 10.5 million adults in Ontario, Canada, from 1 April 2002 to 31 March 2009. We linked the Canadian Institute for Health Information Discharge Abstract Database, the Registered Persons Database and the database of the Ontario Cancer Registry to assess procedures used over the period. Data on demographics were collected. Trends were assessed using time series analysis. RESULTS Over the 7-year period, 8189 open and 1079 laparoscopic elective operations for rectal cancer were identified. The annual rate of laparoscopic rectal cancer procedures increased from 0.60 per 100,000 population in 2003 to 2.24 per 100,000 population in 2008 (P < 0.01). Laparoscopic patients were similar to open with respect to age (66.5 ± 11.8 vs 66.2 ± 12.1 years; standardized difference 0.02), gender (63.2%vs 59.4%; standardized difference 0.08), Charlson Comorbidity Index score (standardized difference < 0.1) and socioeconomic status (standardized difference < 0.1). CONCLUSION Laparoscopic rectal cancer surgery rates are increasing in Ontario. Ongoing research regarding the long-term safety and effectiveness of the laparoscopic approach for rectal cancer surgeries may lead to greater increases in its utilization.
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Affiliation(s)
- R P Musselman
- Department of Surgery, University of Ottawa, Ottawa, Ontario, Canada.
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Kwok CB, Ho FC, Li CW, Ngan AHW, Chan D, Chan BP. Compression-induced alignment and elongation of human mesenchymal stem cell (hMSC) in 3D collagen constructs is collagen concentration dependent. J Biomed Mater Res A 2012. [PMID: 23184852 DOI: 10.1002/jbm.a.34475] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Controlling cell organization is important in tissue engineering. Guidance by aligned features on scaffolds or stimulation by physical signals can be used to induce cell alignment. We have previously demonstrated a preferred alignment of human MSCs (hMSCs) along the compression loading axis in 3D collagen construct. In this study, we aim to investigate the collagen concentration dependence of the compression-induced hMSC organization. Results demonstrated that the compression-induced alignment and elongation of hMSCs exhibited a biphasic dose-dependent relationship with collagen concentration, and associated well with both collagen ligand density and elastic modulus of the constructs. Moreover, collagen concentration and compression loading significantly affected the expression level of integrin beta 1 and antibody neutralization against this molecule aborted the compression-induced alignment and elongation responses.
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Affiliation(s)
- C B Kwok
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China
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Abstract
AIM The safety and efficacy of laparoscopic surgery for colon cancer is well established but its uptake in the province has not been previously explored. We report an investigation of the trends of open and laparoscopic surgery for colon cancer in Ontario, Canada. METHOD A retrospective cross-sectional time-series analysis examining population-based rates of elective surgery for colon cancer among 10.5 million adults in Ontario was conducted from 1 April 2002 to 31 March 2009. Databases were linked to assess quarterly elective procedure rates over time. RESULTS During the study period, 3950 laparoscopic and 13 048 open elective colon cancer operations were performed in Ontario. The overall quarterly rate of colon cancer surgery remained stable at an average of 5.8 per 100000 population (P=0.10). From the first and last quarter, the rate of laparoscopic operations increased nearly threefold from 0.8 to 2.2 per 100000 population with a notable increase after 2005 (P<0.01). In contrast, open surgery decreased by more than 30% from 5.3 to 3.5 per 100 000 population (P<0.01). If current trends continue, the projected proportion of laparoscopic colon operations is estimated to reach 41% by 2015. Patients receiving open surgery had a significantly higher preoperative comorbidity (Charlson comorbidity score≥3) than those having laparoscopy (47.8%vs 39.1%, standardized difference 0.26). CONCLUSION Trends in Ontario of laparoscopic colon cancer surgery show an increase between 2002 and 2009, but the incidence remains lower than for open surgery.
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Affiliation(s)
- B P Chan
- Division of General Surgery, Ottawa Hospital, University of Ottawa, Ontario, Canada.
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Affiliation(s)
- Barbara Pui Chan
- Medical Engineering Program, Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China
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Au-Yeung KL, Sze KY, Sham MH, Chan BP. Development of a micromanipulator-based loading device for mechanoregulation study of human mesenchymal stem cells in three-dimensional collagen constructs. Tissue Eng Part C Methods 2010; 16:93-107. [PMID: 19368498 DOI: 10.1089/ten.tec.2008.0707] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mechanical signal is important for regulating cellular activities, including proliferation, metabolism, matrix production, and orientation. Bioreactors with loading functions can be used to precondition cells in three-dimensional (3D) constructs so as to study the cellular responses to mechanical stimulation. However, full-scale bioreactor is not always an affordable option considering the high cost of equipment and the liter-sized medium with serum and growth factor supplements. In this study, a custom-built loading system was developed by coupling a conventional camera-equipped inverted research microscope with two micromanipulators. The system was programmed to deliver either cyclic compressive loading with different frequencies or static compressive loading for 1 week to investigate the cellular responses of human mesenchymal stem cells (hMSCs) entrapped in a 3D construct consists of reconstituted collagen fibers. Cellular properties, including their alignment, cytoskeleton, and cell metabolism, and properties of matrix molecules, such as collagen fiber alignment and glycosaminoglycan deposition, were evaluated. Using a MatLab-based image analysis program, reorientation of the entrapped cells from a random distribution to a preferred alignment along the loading direction in constructs with both static and cyclic compression has been demonstrated, but no such alignment was found in the free-floating controls. Fluorescent staining on filamentous actin cytoskeleton also confirmed the finding. Nevertheless, the collagen fiber meshwork entrapping the hMSCs remained randomly distributed, and no change in cellular metabolism and glycosaminoglycans production was noted. The current study provides a simple and affordable option toward setting up a mechanoregulation facility based on existing laboratory equipment and sheds new insights on the effect of mechanical loading on the alignment of hMSCs in 3D collagen constructs.
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Affiliation(s)
- Kwan Lok Au-Yeung
- The University of Hong Kong , Hong Kong Special Administrative Region, China
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Chan BP, Leong KW. Scaffolding in tissue engineering: general approaches and tissue-specific considerations. Eur Spine J 2008; 17 Suppl 4:467-79. [PMID: 19005702 DOI: 10.1007/s00586-008-0745-3] [Citation(s) in RCA: 794] [Impact Index Per Article: 49.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 07/09/2008] [Accepted: 07/09/2008] [Indexed: 12/19/2022]
Abstract
Scaffolds represent important components for tissue engineering. However, researchers often encounter an enormous variety of choices when selecting scaffolds for tissue engineering. This paper aims to review the functions of scaffolds and the major scaffolding approaches as important guidelines for selecting scaffolds and discuss the tissue-specific considerations for scaffolding, using intervertebral disc as an example.
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Affiliation(s)
- B P Chan
- Medical Engineering Program, Department of Mechanical Engineering, The University of Hong Kong, Room 711, Haking Wong Building, Pokfulam Road, Hong Kong SAR, China.
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Hui TY, Cheung KMC, Cheung WL, Chan D, Chan BP. In vitro chondrogenic differentiation of human mesenchymal stem cells in collagen microspheres: influence of cell seeding density and collagen concentration. Biomaterials 2008; 29:3201-12. [PMID: 18462789 DOI: 10.1016/j.biomaterials.2008.04.001] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Accepted: 04/01/2008] [Indexed: 10/22/2022]
Abstract
Given the inadequacies of existing repair strategies for cartilage injuries, tissue engineering approach using biomaterials and stem cells offers new hope for better treatments. Recently, we have fabricated injectable collagen-human mesenchymal stem cell (hMSC) microspheres using microencapsulation. Apart from providing a protective matrix for cell delivery, the collagen microspheres may also act as a bio-mimetic matrix facilitating the functional remodeling of hMSCs. In this study, whether the encapsulated hMSCs can be pre-differentiated into chondrogenic phenotype prior to implantation has been investigated. The effects of cell seeding density and collagen concentration on the chondrogenic differentiation potential of hMSCs have been studied. An in vivo implantation study has also been conducted. Fabrication of cartilage-like tissue micro-masses was demonstrated by positive immunohistochemical staining for cartilage-specific extracellular matrix components including type II collagen and aggrecan. The meshwork of collagen fibers was remodeled into a highly ordered microstructure, characterized by thick and parallel bundles, upon differentiation. Higher cell seeding density and higher collagen concentration favored the chondrogenic differentiation of hMSCs, yielding increased matrix production and mechanical strength of the micro-masses. These micro-masses were also demonstrated to integrate well with the host tissue in NOD/SCID mice.
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Affiliation(s)
- T Y Hui
- Medical Engineering Program, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
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Chan OCM, So KF, Chan BP. Fabrication of nano-fibrous collagen microspheres for protein delivery and effects of photochemical crosslinking on release kinetics. J Control Release 2008; 129:135-43. [PMID: 18514352 DOI: 10.1016/j.jconrel.2008.04.011] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 04/14/2008] [Accepted: 04/14/2008] [Indexed: 10/22/2022]
Abstract
Protein compatibility is important for protein drug delivery using microsphere-based devices. Collagen has excellent protein compatibility but has poor mechanical stability for microsphere fabrication and open meshwork for controlled release. In this study, a protein-compatible fabrication method for injectable collagen microspheres has been developed. The surface morphology, interior microstructure and protein release characteristics of collagen microspheres were investigated. Moreover, effects of photochemical crosslinking on these characteristics were also studied. Finally, the mechanisms governing the protein release and the retention of protein bioactivity were studied. Stable and injectable collagen microspheres consisting of nano-fibrous meshwork were successfully fabricated under ambient conditions in an organic solvent and crosslinking reagent-free manner. These microspheres have open meshwork and showed large initial burst and rapid release of proteins. Photochemical crosslinking significantly reduced the initial burst effect and controlled the protein release in a photosensitizer dose-dependent manner without significantly altering the mesh size. We further demonstrated that there was significantly higher protein retention within the photochemically crosslinked collagen microspheres as compared with the uncrosslinked, suggesting a secondary retention mechanism. Lastly, both surfactant treatment and photochemical crosslinking did not compromise the bioactivity of the encapsulated proteins. In summary, this study reports a novel collagen microsphere-based protein delivery system and demonstrates the possibility to use photochemical crosslinking as the secondary retention mechanism for proteins.
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Affiliation(s)
- O C M Chan
- Medical Engineering, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
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Wong HL, Wang MX, Cheung PT, Yao KM, Chan BP. A 3D collagen microsphere culture system for GDNF-secreting HEK293 cells with enhanced protein productivity. Biomaterials 2007; 28:5369-80. [PMID: 17764735 DOI: 10.1016/j.biomaterials.2007.08.016] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Accepted: 08/09/2007] [Indexed: 11/17/2022]
Abstract
Mammalian cell culture technology has been used for decades in mass production of therapeutic proteins. However, unrestricted cell proliferation usually results in low-protein productivity. Controlled proliferation technologies such as metabolism intervention and genetic manipulation are therefore applied to enhance the productivity. Nevertheless, these strategies induced growth arrest with reduced viability and increased apoptosis. In this study, we report a new controlled proliferation technology by encapsulating human embryonic kidney (HEK) 293 cells over-expressing glial-derived neurotrophic factor (GDNF) in 3D collagen microspheres for extended culture. We investigated the viability, proliferation, cell cycle and GDNF productivity of HEK293 cells in microspheres as compared to monolayer culture. This system provides a physiologically relevant tissue-like environment for cells to grow and exerts proliferation control throughout the culture period without compromising the viability. A significant increase in the production rate of GDNF was found in the 3D microsphere system comparing with the monolayer culture. GDNF productivity was also significantly affected by the initial cell number and the serum concentration. The secreted GDNF was still bioactive as it induced neurite extension in PC12 cells. In summary, the 3D collagen microsphere system presents a cost-effective controlled growth technology for protein production in pharmaceutical manufacturing.
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Affiliation(s)
- Hoi-Ling Wong
- Medical Engineering Program, Department of Mechanical Engineering, Faculty of Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong
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Chan BP, Hui TY, Chan OCM, So KF, Lu W, Cheung KMC, Salomatina E, Yaroslavsky A. Photochemical cross-linking for collagen-based scaffolds: a study on optical properties, mechanical properties, stability, and hematocompatibility. ACTA ACUST UNITED AC 2007; 13:73-85. [PMID: 17518582 DOI: 10.1089/ten.2006.0004] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Collagen presents an attractive biomaterial for tissue engineering because of its excellent biocompatibility and negligible immunogenicity. However, some intrinsic features related to the mechanical stability and thrombogenicity limit its applications in orthopedic and vascular tissue engineering. Photochemical cross-linking is an emerging technique able to stabilize tissue grafts and improve the physicochemical properties of collagen-based structures. However, other important properties of collagen-based structures and the effect of processing parameters on these properties have not been explored. In this study, we aim to investigate the dose dependence of tensile and swelling properties on two parameters, namely, laser energy fluence and rose Bengal photosensitizer concentration. We also study the compression properties using cyclic compression test, long-term stability using subcutaneous implantation, and hematocompatibility using platelets adhesion test, of cross-linked collagen structures. Moreover, because limited optical penetration in turbid media is the major obstacle for light-based techniques, we also characterize the optical properties, which partially determine the effective optical penetration depth in collagen gel samples, during photochemical cross-linking. Laser energy fluence and rose Bengal concentration are important parameters affecting the cross-linking efficiency, which was characterized as the mechanical and the swelling properties, in a dose-dependent manner. Under the experimental conditions in this study, the peak fluence was 12.5 J/cm2 and the minimal rose Bengal concentration for effective cross-linking was >0.00008% (0.786 micromol). Photochemical cross-linking also enhanced the compression strength and long-term stability of collagen structures without compromising the tissue compatibility. Furthermore, photochemical cross-linking reduced platelet adhesion and abolished fibrin mesh formation, thereby improving the hematocompatibility of collagen structures. These results suggest the feasibility of using the photochemically cross-linked collagen structures for orthopedic and vascular tissue engineering. Finally, the effective optical penetration depth in collagen gel samples is wavelength and rose Bengal concentration dependent, and was approximately 12 mm at 514 nm at 0.001% (9.825 micromol), the rose Bengal concentration mostly used in this study.
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Affiliation(s)
- B P Chan
- Medical Engineering Program, Department of Mechanical Engineering, University of Hong Kong, Hong Kong Special Administrative Region, China, and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, USA.
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Tse THZ, Chan BP, Chan CM, Lam J. Mathematical modeling of guided neurite extension in an engineered conduit with multiple concentration gradients of nerve growth factor (NGF). Ann Biomed Eng 2007; 35:1561-72. [PMID: 17520368 DOI: 10.1007/s10439-007-9328-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Accepted: 05/09/2007] [Indexed: 12/11/2022]
Abstract
Neurotrophic factors such as nerve growth factor (NGF) provide essential cues to navigate growing axon toward their targets. Concentration and concentration gradient of NGF are key parameters affecting the growth rate and direction of neurites and axons. However, the maximum distance for guided nerve growth under stimulation of a single concentration gradient is limited and is thus unfavorable in nerve regeneration. Since the sensitivity of PC12 cells to NGF signals is restorable even after brief removal of the factors, exposure to multiple concentration gradients of the factor can achieve longer distances and greater rates of guided growth. In this study, a mathematical model simulating nerve growth in a virtually constructed nerve conduit incorporating multiple NGF concentration gradients is established. Using a genetic algorithm, optimized initial profiles of NGF able to achieve 4.5 cm of guided growth with a significantly improved growth rate has been obtained. The model also predicts an inverse relationship between the diffusion coefficient of the factor and the neurite growth rate. This model provides a useful tool for evaluating various conduit designs before fabrication and evaluation.
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Affiliation(s)
- T H Z Tse
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
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Abstract
Growth factors potentially promote tendon healing. Understanding the right time to administer growth factors and the dosage of growth factors are prerequisites for designing effective cytokine therapy. We investigated the supplementation-time dependence of the effects of platelet-derived growth factor isoform B at various dosages on tendon healing, and the temporal responsiveness of healing tendon toward platelet-derived growth factor. Platelet-derived growth factor isoform B at various dosages (0, 10, 100, or 1000 ng) was delivered into the gap wound of rat patellar tendons via microsyringe injection on Day 3 or Day 7 after injury. Tendon specimens were harvested on Day 14 for measurement of cell proliferation, pyridinoline content, and mechanical properties. We found increased proliferative response only when the growth factor was supplemented on Day 3 after injury, whereas supplementation on Day 7 resulted in greater peak load, cross-sectional area, and pyridinoline content. The ultimate stress did not change. Our findings suggest supplementation of platelet-derived growth factor isoform B at Day 7 benefits the mechanical properties and maturation of healing tendons. We also found platelet-derived growth factor receptor beta expressing cells at the remodeling site as much as 6 months after injury, suggesting healing tendon also may be responsive to long-term delivery of platelet-derived growth factor.
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Affiliation(s)
- B P Chan
- Medical Engineering Program, Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, China.
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Abstract
Collagen is a natural biomaterial with excellent biocompatibility. However, unprocessed collagen has low stability and weak mechanical strength, which limits its application in tissue engineering. The current study aimed to improve the physicochemical properties of collagen scaffolds by using photochemical crosslinking. Collagen gel was reconstituted and photochemically crosslinked by using laser irradiation in the presence of a photosensitizer. Scanning electron microscope was used to characterize the surface and cross-sectional morphology. Stress-strain relationship and other mechanical properties were determined by uniaxial tensile tests. Thermostability and water-binding capacities also were analyzed by using differential scanning calorimetry and swelling ratio measurements, respectively. Photochemically crosslinked porous structures showed fine microstructure with interconnected micron-sized pores, whereas uncrosslinked controls only showed macrosheet-like structures. The stabilizing effect of photochemical crosslinking also was revealed by retaining the three-dimensional lamellae-like structures after thermal analysis in crosslinked membranes but not in the controls. Photochemical crosslinking also significantly reduced the swelling ratio, improved the stress-strain relationship, peak load, ultimate stress, rupture strain, and tangent modulus of collagen membranes. The current study showed that an innovative photochemical crosslinking process was able to produce collagen scaffolds with fine microstructures; to strengthen, stiffen, and stabilize collagen membranes; and to modify their swelling ratio. This may broaden the use of collagen-based scaffolds in tissue engineering, particularly for weight-bearing tissues.
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Affiliation(s)
- B P Chan
- Medical Engineering Program, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China.
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Chan BP, Yuen WF, Lee WH, Wong SN, Chung TY, Wu YJ, Pang SF. Immunomodulating Effects of CKBM on the Cytokine Production in Peripheral Blood Mononuclear Cells (PBMCs) from Healthy Volunteers. Immunopharmacol Immunotoxicol 2004; 26:177-92. [PMID: 15209354 DOI: 10.1081/iph-120037713] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The current study investigated the immunomodulating effect of CKBM on cytokine induction in peripheral blood mononuclear cells (PBMCs) isolated from 20 healthy volunteers. Cytometric Bead Analysis (CBA) was used to study IL-2, IL-4, IL-6, IL-10, TNF-alpha and IFN-gamma. TNF-alpha and IL-6 were significantly increased in a CKBM dose- and time-dependent manner. Flow cytometry analysis showed an increased intracellular staining of IL-6 but not of TNF-alpha in CKBM treated PBMCs. In addition, MTT cell cytotoxicity assay showed that CKBM concentrations below 5% did not significantly affect the metabolic activities of PBMCs. The current study indicated that CKBM may modulate the immune response by inducing the secretions of TNF-alpha and IL-6, which are cytokine mediators of innate immunity and inflammation preparing or "priming" the body to combat diseases.
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Affiliation(s)
- B P Chan
- The University of Hong Kong, Hong Kong Special Administrative Region, China.
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Wong MWN, Tang YYN, Lee SKM, Fu BSC, Chan BP, Chan CKM. Effect of dexamethasone on cultured human tenocytes and its reversibility by platelet-derived growth factor. J Bone Joint Surg Am 2003; 85:1914-20. [PMID: 14563798 DOI: 10.2106/00004623-200310000-00008] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Many cases of tendon rupture after glucocorticoid injections have been reported in the literature. Despite previous studies on the histological and biomechanical changes in tendons after glucocorticoid injections, the role of glucocorticoid in causing tendon rupture still remains controversial. The objective of this study was to determine whether glucocorticoid has deleterious effects on the cellular metabolism and collagen production of cultured human tenocytes and the reversibility of these effects by platelet-derived growth factor-BB (PDGFBB). METHODS Primary cultures of human tenocytes obtained from explants of healthy patellar tendon, harvested during anterior cruciate ligament reconstructions, were performed. The effects on cell viability, cell proliferation, and induction of apoptosis were measured by [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, 5-bromo-deoxyuridine incorporation, and DNA fragmentation assay, respectively. The effect on collagen synthesis was measured by (3) H-proline incorporation assay. RESULTS The number of viable cells was decreased, in a dose-dependent manner, by the administration of 10 (-9) to 10 (-4) -M dexamethasone. This dose range also suppressed cell proliferation. No apoptotic effect was detected. Treatment with 10 (-6) -M dexamethasone significantly reduced the amount of collagen synthesis. Co-incubation with 10 ng/mL of PDGFBB significantly reversed the effects caused by 10 (-6) -M dexamethasone. CONCLUSIONS Dexamethasone significantly decreased cell viability, suppressed cell proliferation, and reduced collagen synthesis in cultured human tenocytes. The effects were reversed by the simultaneous administration of PDGFBB.
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Affiliation(s)
- Margaret Wan Nar Wong
- Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Shatin.
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Fu SC, Qin L, Leung CK, Chan BP, Chan KM. Regular moderate exercise training prevents decrease of CD4+ T-lymphocytes induced by a single bout of strenuous exercise in mice. Can J Appl Physiol 2003; 28:370-81. [PMID: 12955865 DOI: 10.1139/h03-027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The biphasic effects of exercise training on the immune system have been studied extensively and represented by the well-known J-shaped curve with respect to training intensity. However, the relationship and interactions between "beneficial" exercise training and "harmful" strenuous exercise have not been researched. This study was designed to determine whether regular moderate exercise training could affect the changes of percentage of T-lymphocytes induced by a single bout of strenuous exercise. A protocol to run uphill on a 10 degrees tilted treadmill for 4 weeks was employed as moderate exercise training in mice, while a sedentary control group of mice was exposed to the same handling stress without training. The trained and untrained mice were then exposed to a single bout of strenuous exercise until exhaustion. Total leukocytes were collected from spleen and peripheral blood at 0 hr, 3 hrs, and 24 hrs postexhaustion, as well as from the control groups. Flow cytometric analyses were conducted to determine the percentages of selected leukocyte populations. It was demonstrated that moderate exercise training prevented the decrease of CD4+ but stimulated the increase of CD25+ CD8+ T-lymphocytes induced by a single bout of strenuous exercise, indicating an adaptive response that can affect changes of leukocyte subpopulations.
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Affiliation(s)
- Sai Chuen Fu
- Department of Orthopaedics and Traumatology, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong
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Fu SC, Wong YP, Chan BP, Pau HM, Cheuk YC, Lee KM, Chan KM. The roles of bone morphogenetic protein (BMP) 12 in stimulating the proliferation and matrix production of human patellar tendon fibroblasts. Life Sci 2003; 72:2965-74. [PMID: 12706484 DOI: 10.1016/s0024-3205(03)00169-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Recombinant human (rh) bone morphogenetic protein 12 (BMP12) is proved to induce the formation of tendon and ligament tissues in animal experiments. But the roles of BMP12 on tissue regeneration in human tendons remain unexplored. In the present study, healthy human patellar tendon samples were collected for histological examination and preparation of tendon fibroblast culture. Immunohistochemical staining showed that BMP12 was detected on healthy patellar tendon samples, only located on active tenoblasts and perivascular mesenchymal cells but not in interstitial tenocytes. The expression of PCNA and procollagen type I also exhibited a similar distribution. It indicates that BMP12 may be involved in matrix remodeling process in adult tissues. In vitro studies showed that rhBMP12 could increase proliferation of tendon fibroblasts and increase the gene expression of procollagen type I and type III, but decrease the gene expression of decorin in tendon fibroblasts culture. Our findings suggest that BMP12 may play a role in early phases of tissue regeneration in tendons.
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Affiliation(s)
- Sai Chuen Fu
- Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong, China
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Widjaja LS, Chan BP, Chen H, Ong BKC, Pang YT. Variance analysis applied to a stroke pathway: how this can improve efficiency of healthcare delivery. Ann Acad Med Singap 2002; 31:425-30. [PMID: 12161876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
INTRODUCTION Stroke is a complicated disease that requires a multidisciplinary approach for its management. We postulated that variance analysis applied to a stroke pathway, by identifying major problem areas and encouraging timely corrective actions, would lead to more efficient healthcare delivery to hospitalised stroke patients. MATERIALS AND METHODS Prospectively collected variance data from consecutive stroke patients discharged from a tertiary hospital in Singapore during a 3-month period in 2000 were used to identify the major variances causing increased length of stay. These were compared and contrasted to variance data collected during the same 3-month period in the subsequent year (2001), after the implementation of stroke pathway and the availability of monthly variance analysis reports. Patient characteristics and outcome measures were also compared between the two study periods. RESULTS The four major variances that accounted for increased length of stay were, in descending order of the number of patients affected, awaiting bed availability in step-down facilities, delay in head computed tomographic scan performance, awaiting family's decision on discharge plan and incomplete application submitted to step-down facilities. After implementation of the stroke pathway with ongoing variance analysis, all four variances showed different extent of improvements. There were no significant differences in patient characteristics between the two study periods, whereas the average length of stay significantly diminished in the late study period with a trend for decreased in-hospital mortality, compared to the early study period. CONCLUSION Variance analysis applied in the context of a stroke pathway was effective in identifying major variances causing increased length of stay. This allowed targeted intervention to improve efficiency of healthcare delivery to stroke patients.
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Affiliation(s)
- L S Widjaja
- Department of Nursing, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074
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Chan BP, Fu S, Qin L, Lee K, Rolf CG, Chan K. Effects of basic fibroblast growth factor (bFGF) on early stages of tendon healing: a rat patellar tendon model. Acta Orthop Scand 2000; 71:513-8. [PMID: 11186411 DOI: 10.1080/000164700317381234] [Citation(s) in RCA: 163] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We studied the effects of basic fibroblast growth factor (bFGF) on cell proliferation, type III collagen expression, ultimate stress and the pyridinoline content in the early stages of healing in rat patellar tendon. 96 male Sprague Dawley rats were injected with increasing doses of basic fibroblast growth factor (bFGF) at 3 days after a "window defect" was induced in the mid-part of the patellar tendon. They were killed at 7 and 14 days after the injury. A dose-dependent increase in the number of proliferating cells and the level of expression of type III collagen was demonstrated at only 7 days post-injury. On the other hand, we found no effects of bFGF on ultimate stress and the pyridinoline content of healing tendons. Only time significantly affected both strength-associated parameters. We showed that in vivo supplementation with bFGF affected the initial events of healing such as cell proliferation and type III collagen expression.
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Affiliation(s)
- B P Chan
- Department of Orthopedics & Traumatology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT.
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