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Peng Y, Zhuang Y, Liu Y, Le H, Li D, Zhang M, Liu K, Zhang Y, Zuo J, Ding J. Bioinspired gradient scaffolds for osteochondral tissue engineering. EXPLORATION (BEIJING, CHINA) 2023; 3:20210043. [PMID: 37933242 PMCID: PMC10624381 DOI: 10.1002/exp.20210043] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 01/05/2023] [Indexed: 11/08/2023]
Abstract
Repairing articular osteochondral defects present considerable challenges in self-repair due to the complex tissue structure and low proliferation of chondrocytes. Conventional clinical therapies have not shown significant efficacy, including microfracture, autologous/allograft osteochondral transplantation, and cell-based techniques. Therefore, tissue engineering has been widely explored in repairing osteochondral defects by leveraging the natural regenerative potential of biomaterials to control cell functions. However, osteochondral tissue is a gradient structure with a smooth transition from the cartilage to subchondral bone, involving changes in chondrocyte morphologies and phenotypes, extracellular matrix components, collagen type and orientation, and cytokines. Bioinspired scaffolds have been developed by simulating gradient characteristics in heterogeneous tissues, such as the pores, components, and osteochondrogenesis-inducing factors, to satisfy the anisotropic features of osteochondral matrices. Bioinspired gradient scaffolds repair osteochondral defects by altering the microenvironments of cell growth to induce osteochondrogenesis and promote the formation of osteochondral interfaces compared with homogeneous scaffolds. This review outlines the meaningful strategies for repairing osteochondral defects by tissue engineering based on gradient scaffolds and predicts the pros and cons of prospective translation into clinical practice.
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Affiliation(s)
- Yachen Peng
- Department of OrthopedicsChina‐Japan Union Hospital of Jilin UniversityChangchunP. R. China
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchunP. R. China
| | - Yaling Zhuang
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchunP. R. China
| | - Yang Liu
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchunP. R. China
- Institute of BioengineeringÉcole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland
| | - Hanxiang Le
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchunP. R. China
| | - Di Li
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchunP. R. China
| | - Mingran Zhang
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchunP. R. China
| | - Kai Liu
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchunP. R. China
| | - Yanbo Zhang
- Department of OrthopedicsChina‐Japan Union Hospital of Jilin UniversityChangchunP. R. China
| | - Jianlin Zuo
- Department of OrthopedicsChina‐Japan Union Hospital of Jilin UniversityChangchunP. R. China
| | - Jianxun Ding
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchunP. R. China
- School of Applied Chemistry and EngineeringUniversity of Science and Technology of ChinaHefeiP. R. China
- Jilin Biomedical Polymers Engineering Laboratory, Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchunP. R. China
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Higuera GA, Ramos T, Gloria A, Ambrosio L, Di Luca A, Pechkov N, de Wijn JR, van Blitterswijk CA, Moroni L. PEOT/PBT Polymeric Pastes to Fabricate Additive Manufactured Scaffolds for Tissue Engineering. Front Bioeng Biotechnol 2021; 9:704185. [PMID: 34595158 PMCID: PMC8476768 DOI: 10.3389/fbioe.2021.704185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 08/30/2021] [Indexed: 11/13/2022] Open
Abstract
The advantages of additive manufactured scaffolds, as custom-shaped structures with a completely interconnected and accessible pore network from the micro- to the macroscale, are nowadays well established in tissue engineering. Pore volume and architecture can be designed in a controlled fashion, resulting in a modulation of scaffold’s mechanical properties and in an optimal nutrient perfusion determinant for cell survival. However, the success of an engineered tissue architecture is often linked to its surface properties as well. The aim of this study was to create a family of polymeric pastes comprised of poly(ethylene oxide therephthalate)/poly(butylene terephthalate) (PEOT/PBT) microspheres and of a second biocompatible polymeric phase acting as a binder. By combining microspheres with additive manufacturing technologies, we produced 3D scaffolds possessing a tailorable surface roughness, which resulted in improved cell adhesion and increased metabolic activity. Furthermore, these scaffolds may offer the potential to act as drug delivery systems to steer tissue regeneration.
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Affiliation(s)
- Gustavo A Higuera
- Institute for BioMedical Technology and Technical Medicine (MIRA), Tissue Regeneration Department, University of Twente, Enschede, Netherlands
| | - Tiago Ramos
- Institute of Ophthalmology, University College of London, London, United Kingdom
| | - Antonio Gloria
- Institute of Polymers, Composites and Biomaterials, National Research Council of Italy, Naples, Italy
| | - Luigi Ambrosio
- Institute of Polymers, Composites and Biomaterials, National Research Council of Italy, Naples, Italy
| | - Andrea Di Luca
- Institute for BioMedical Technology and Technical Medicine (MIRA), Tissue Regeneration Department, University of Twente, Enschede, Netherlands
| | - Nicholas Pechkov
- Institute for BioMedical Technology and Technical Medicine (MIRA), Tissue Regeneration Department, University of Twente, Enschede, Netherlands
| | - Joost R de Wijn
- Institute for BioMedical Technology and Technical Medicine (MIRA), Tissue Regeneration Department, University of Twente, Enschede, Netherlands
| | - Clemens A van Blitterswijk
- MERLN Institute for Technology-inspired Regenerative Medicine, Complex Tissue Regeneration Department, Maastricht University, Maastricht, Netherlands
| | - Lorenzo Moroni
- MERLN Institute for Technology-inspired Regenerative Medicine, Complex Tissue Regeneration Department, Maastricht University, Maastricht, Netherlands
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3
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Heparin-Eluting Tissue-Engineered Bioabsorbable Vascular Grafts. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11104563] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The creation of small-diameter tissue-engineered vascular grafts using biodegradable materials has the potential to change the quality of cardiovascular surgery in the future. The implantation of these tissue-engineered arterial grafts has yet to reach clinical application. One of the reasons for this is thrombus occlusion of the graft in the acute phase. In this paper, we first describe the causes of accelerated thrombus formation and discuss the drugs that are thought to inhibit thrombus formation. We then review the latest research on methods to locally bind the anticoagulant heparin to biodegradable materials and methods to extend the duration of sustained heparin release. We also discuss the results of studies using large animal models and the challenges that need to be overcome for future clinical applications.
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4
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Sustained release of TGF-β 3 from polysaccharide nanoparticles induces chondrogenic differentiation of human mesenchymal stromal cells. Colloids Surf B Biointerfaces 2020; 189:110843. [PMID: 32044676 DOI: 10.1016/j.colsurfb.2020.110843] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 01/30/2020] [Accepted: 02/01/2020] [Indexed: 11/24/2022]
Abstract
Medical treatment of certain diseases and biomedical implants are tending to use delivery systems on the nanoscale basis for biologically active factors including drugs (e. g. antibiotics) or growth factors. Nanoparticles are a useful tool to deliver bioactive substances of different chemical nature directly to the site where it is required in the patient. Here we developed three innovative delivery systems based on different polysaccharides in order to induce a sustained release of TGF-β3 to mediate chondrogenesis of human mesenchymal stromal cells. We were able to encapsulate the protein into nanoparticles and subsequently release TGF-β3 from these particles. The protein was still active and was able to induce chondrogenic differentiation of human mesenchymal stromal cells.
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Jun Y, Oh H, Karpoormath R, Jha A, Patel R. Role of microsphere as drug carrier for osteogenic differentiation. INT J POLYM MATER PO 2020. [DOI: 10.1080/00914037.2020.1713783] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Yuju Jun
- Department of Nano Science and Engineering, Integrated Science and Engineering Division (ISED), Underwood International College, Yonsei University, Incheon, South Korea
| | - Hyunyoung Oh
- Department of Energy and Environmental Science and Engineering, Integrated Science and Engineering Division (ISED), Underwood International College, Yonsei University, Incheon, South Korea
| | - Rajshekhar Karpoormath
- Department of Pharmaceutical Chemistry, College of Health Sciences, University of Kwa Zulu Natal, Durban, South Africa
| | - Amitabh Jha
- Department of Chemistry, Acadia University, Wolfville, Canada
| | - Rajkumar Patel
- Department of Energy and Environmental Science and Engineering, Integrated Science and Engineering Division (ISED), Underwood International College, Yonsei University, Incheon, South Korea
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Nie X, Chuah YJ, He P, Wang DA. Engineering a multiphasic, integrated graft with a biologically developed cartilage-bone interface for osteochondral defect repair. J Mater Chem B 2019; 7:6515-6525. [PMID: 31576900 DOI: 10.1039/c9tb00822e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Tissue engineering is a promising approach to repair osteochondral defects, yet successful reconstruction of different layers in an integrated graft, especially the interface remains challenging. The multiphasic, functionally integrated tissue engineering graft described herein mimics the entire osteochondral tissue in terms of structure and composition at the cartilage, bone and cartilage-bone interface layer to repair osteochondral defects. In this manuscript, we report the fabrication of a multiphasic graft via bonding of a cartilaginous hydrogel and a sintered poly(lactic-co-glycolic acid) microsphere scaffold by an endogenous fibrotic cartilaginous extracellular matrix. We demonstrated that culturing chondrocytes within the alginate hydrogel conjugated to the poly(lactic-co-glycolic acid) scaffold allows for (i) gradient transition and integration from the cartilage layer to the subchondral bone layer as assessed by scanning electron microscopy, histology and biochemistry, and (ii) superior tissue repair efficacy in a rabbit knee defect model. Industrialization of the graft remains an unsolved challenge as after decellularization the tissue repair efficacy of the graft decreased. Taken together, the multiphasic osteochondral graft repaired the osteochondral defects successfully and has the potential to be applied clinically as an implant in orthopaedic surgery.
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Affiliation(s)
- Xiaolei Nie
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore
| | - Yon Jin Chuah
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore
| | - Pengfei He
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore
| | - Dong-An Wang
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore and Department of Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR.
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7
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Liu H, Du K, Li D, Du Y, Xi J, Xu Y, Shen Y, Jiang T, Webster TJ. A high bioavailability and sustained-release nano-delivery system for nintedanib based on electrospray technology. Int J Nanomedicine 2018; 13:8379-8393. [PMID: 30587966 PMCID: PMC6294062 DOI: 10.2147/ijn.s181002] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Nintedanib is a new tyrosine kinase inhibitor and growth factor antagonist. It can be used to treat idiopathic pulmonary fibrosis diseases. Nintedanib has poor solubility in the intestinal tract environment, which leads to low bioavailability of just 4.7%. METHODS In this study, a nintedanib solid dispersion was prepared by electrospray technology with an optimized formula (nintedanib:PVPK30:Soybean lecithin=1:5:0.25) and electrospray parameters (21 kV voltage, 18 cm receiving distance, 0.3 mL/h solution flow rate, 0.5 mm pinhole inner diameter). RESULTS The accumulative release rate of the optimized solid dispersion was more than 60% in 30 minutes and 100% in 60 minutes. The size distribution was uniform and the surface observed with scanning electron microscopy (SEM) was smooth. The DSC and X-ray diffraction results showed that nintedanib existed in the solid dispersion through an amorphous form. Nintedanib solid dispersion sustained-release capsules were prepared to prolong drug release, improve patient compliance and reduce side effects. The accumulative release rate from the sustained release capsules was 35.17%, 54.78%, 70.58%, and 93.93% after 2 h, 6 h, 8 h, and 12 h, respectively, having obvious sustained release effects in vitro. The release behavior of solid dispersion sustained-release capsules in vitro was in accordance with the Ritger-Peppas model. The in vivo studies of nintedanib soft capsules, solid dispersion and nintedanib sustained release capsules in SD rats were investigated; the results showed that the Tmax of the soft capsule, solid dispersion and sustained release capsules were 3 h, 2 h, and 6 h, respectively. The Cmax were 2.945 mg/mL, 5.32 mg/mL, and 3.75 mg/mL, respectively, while the AUC0-24 h was 15.124 mg·h/mL, 23.438 mg·h/mL, and 24.584 mg·h/mL, respectively. The relevant bioavailability of the sustained-release capsules was 162.55% compared to the nintedanib soft capsule and 104.89% compared to the nintedanib solid dispersion. CONCLUSION The results suggested superior bioavailability and a sustained-release effect from nintedanib sustained-release capsules, as compared to the reference (commercial nintedanib soft capsule).
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Affiliation(s)
- Hongfei Liu
- School of Pharmacy, Jiangsu University, Zhenjiang 212013, China
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China
| | - Kunyu Du
- School of Pharmacy, Jiangsu University, Zhenjiang 212013, China
| | - Dongli Li
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China
| | - Yi Du
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China
| | - Jumei Xi
- Health of Nepstar Drugstore Chain Company Limited, Wuxi 214000, China
| | - Ying Xu
- School of Pharmacy, Jiangsu University, Zhenjiang 212013, China
| | - Yan Shen
- State Key Laboratory of Natural Medicines, Department of Pharmaceutics, China Pharmaceutical University, Nanjing 210009, China
| | - Tao Jiang
- The Pharmacy Department, Jiangsu Cancer Hospital and Jiangsu Institute of Cancer Research and The Affiliated Cancer Hospital of Nanjing Medical University, Nanjing 210009, China,
| | - Thomas J Webster
- Department of Chemical Engineering, Northeastern University, Boston, MA 02115, USA,
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Gupta V, Khan Y, Berkland CJ, Laurencin CT, Detamore MS. Microsphere-Based Scaffolds in Regenerative Engineering. Annu Rev Biomed Eng 2018. [PMID: 28633566 DOI: 10.1146/annurev-bioeng-071516-044712] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microspheres have long been used in drug delivery applications because of their controlled release capabilities. They have increasingly served as the fundamental building block for fabricating scaffolds for regenerative engineering because of their ability to provide a porous network, offer high-resolution control over spatial organization, and deliver growth factors/drugs and/or nanophase materials. Because they provide physicochemical gradients via spatiotemporal release of bioactive factors and nanophase ceramics, microspheres are a desirable tool for engineering complex tissues and biological interfaces. In this review we describe various methods for microsphere fabrication and sintering, and elucidate how these methods influence both micro- and macroscopic scaffold properties, with a special focus on the nature of sintering. Furthermore, we review key applications of microsphere-based scaffolds in regenerating various tissues. We hope to inspire researchers to join a growing community of investigators using microspheres as tissue engineering scaffolds so that their full potential in regenerative engineering may be realized.
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Affiliation(s)
- Vineet Gupta
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas 66045;
| | - Yusuf Khan
- Department of Orthopaedic Surgery, University of Connecticut Health Campus, Farmington, Connecticut 06030; , .,Department of Materials Science and Engineering, University of Connecticut, Storrs, Connecticut 06269.,Institute for Regenerative Engineering, University of Connecticut Health Campus, Farmington, Connecticut 06030
| | - Cory J Berkland
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas 66045; .,Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045;
| | - Cato T Laurencin
- Department of Orthopaedic Surgery, University of Connecticut Health Campus, Farmington, Connecticut 06030; , .,Department of Materials Science and Engineering, University of Connecticut, Storrs, Connecticut 06269.,Institute for Regenerative Engineering, University of Connecticut Health Campus, Farmington, Connecticut 06030
| | - Michael S Detamore
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, Oklahoma 73019;
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9
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Patel R, Patel M, Kwak J, Iyer AK, Karpoormath R, Desai S, Rarh V. Polymeric microspheres: a delivery system for osteogenic differentiation. POLYM ADVAN TECHNOL 2017. [DOI: 10.1002/pat.4084] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Rajkumar Patel
- School of Electrical and Computer Engineering; The University of Seoul; Seoul 02504 Korea
| | - Madhumita Patel
- Department of Chemistry and Nano Science; Ewha Womans University; Seodaemun-gu Seoul 120-750 South Korea
| | - Jeonghun Kwak
- School of Electrical and Computer Engineering; The University of Seoul; Seoul 02504 Korea
| | - Arun K. Iyer
- Use-inspired Biomaterials & Integrated Nano Delivery (U-Bind) Systems Laboratory, Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health, Sciences; Wayne State University; 259 Mack Ave Detroit MI 48201 USA
| | - Rajshekhar Karpoormath
- Department of Pharmaceutical Chemistry, College of Health Sciences; University of Kwa Zulu Natal; Durban 4000 Africa
| | - Shrojal Desai
- Global Infusion Systems R&D at Hospira; Chicago, IL USA
| | - Vimal Rarh
- Department of Chemistry, S.G.T.B. Khalsa College; University of Delhi; Delhi 110007 India
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10
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Narayanan G, Vernekar VN, Kuyinu EL, Laurencin CT. Poly (lactic acid)-based biomaterials for orthopaedic regenerative engineering. Adv Drug Deliv Rev 2016; 107:247-276. [PMID: 27125191 PMCID: PMC5482531 DOI: 10.1016/j.addr.2016.04.015] [Citation(s) in RCA: 216] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 03/09/2016] [Accepted: 04/17/2016] [Indexed: 02/07/2023]
Abstract
Regenerative engineering converges tissue engineering, advanced materials science, stem cell science, and developmental biology to regenerate complex tissues such as whole limbs. Regenerative engineering scaffolds provide mechanical support and nanoscale control over architecture, topography, and biochemical cues to influence cellular outcome. In this regard, poly (lactic acid) (PLA)-based biomaterials may be considered as a gold standard for many orthopaedic regenerative engineering applications because of their versatility in fabrication, biodegradability, and compatibility with biomolecules and cells. Here we discuss recent developments in PLA-based biomaterials with respect to processability and current applications in the clinical and research settings for bone, ligament, meniscus, and cartilage regeneration.
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Affiliation(s)
- Ganesh Narayanan
- Institute for Regenerative Engineering, University of Connecticut Health Center, Farmington, CT 06030, USA; Raymond and Beverly Sackler Center for Biomedical, Biological, Physical and Engineering Sciences, University of Connecticut Health Center, Farmington, CT 06030, USA; Department of Orthopaedic Surgery, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Varadraj N Vernekar
- Institute for Regenerative Engineering, University of Connecticut Health Center, Farmington, CT 06030, USA; Raymond and Beverly Sackler Center for Biomedical, Biological, Physical and Engineering Sciences, University of Connecticut Health Center, Farmington, CT 06030, USA; Department of Orthopaedic Surgery, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Emmanuel L Kuyinu
- Institute for Regenerative Engineering, University of Connecticut Health Center, Farmington, CT 06030, USA; Raymond and Beverly Sackler Center for Biomedical, Biological, Physical and Engineering Sciences, University of Connecticut Health Center, Farmington, CT 06030, USA; Department of Orthopaedic Surgery, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Cato T Laurencin
- Institute for Regenerative Engineering, University of Connecticut Health Center, Farmington, CT 06030, USA; Raymond and Beverly Sackler Center for Biomedical, Biological, Physical and Engineering Sciences, University of Connecticut Health Center, Farmington, CT 06030, USA; Department of Orthopaedic Surgery, University of Connecticut Health Center, Farmington, CT 06030, USA; School of Medicine, University of Connecticut Health Center, Farmington, CT 06030, USA; Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, CT 06030, USA; Department of Chemical and Biomolecular Engineering, University of Connecticut, Storrs, CT 06269, USA; Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA; Department of Materials Science and Engineering, University of Connecticut, Storrs, CT 06269, USA.
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11
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Liu Y, Nelson T, Cromeens B, Rager T, Lannutti J, Johnson J, Besner GE. HB-EGF embedded in PGA/PLLA scaffolds via subcritical CO 2 augments the production of tissue engineered intestine. Biomaterials 2016; 103:150-159. [DOI: 10.1016/j.biomaterials.2016.06.039] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 05/10/2016] [Accepted: 06/17/2016] [Indexed: 01/30/2023]
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12
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Gupta V, Lyne DV, Laflin AD, Zabel TA, Barragan M, Bunch JT, Pacicca DM, Detamore MS. Microsphere-Based Osteochondral Scaffolds Carrying Opposing Gradients Of Decellularized Cartilage And Demineralized Bone Matrix. ACS Biomater Sci Eng 2016; 3:1955-1963. [PMID: 32793803 DOI: 10.1021/acsbiomaterials.6b00071] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Extracellular matrix (ECM) "raw materials" such as demineralized bone matrix (DBM) and cartilage matrix have emerged as leading scaffolding materials for osteochondral regeneration owing to their capacity to facilitate progenitor/resident cell recruitment, infiltration, and differentiation without adding growth factors. Scaffolds comprising synthetic polymers are sturdy yet generally lack cues for guiding cell differentiation. We hypothesized that opposing gradients of decellularized cartilage (DCC) and DBM in polymeric microsphere-based scaffolds would provide superior regeneration compared to polymer-only scaffolds in vivo. Poly(D,L-lactic-co-glycolic acid) (PLGA) microsphere-based scaffolds were fabricated, either with opposing gradients of DCC and DBM encapsulated (GRADIENT) or without DCC and DBM (BLANK control), and implanted into rabbit osteochondral defects in medial femoral condyles. After 12 weeks, gross morphological evaluation showed that the repair tissue in about 30% of the implants was either slightly or significantly depressed, hinting toward rapid polymer degradation in scaffolds from both of the groups. Additionally, no differences were observed in gross morphology of the repair tissue between the BLANK and GRADIENT groups. Mechanical testing revealed no significant differences in model parameter values between the two groups. Histological observations demonstrated that the repair tissue in both of the groups was fibrous in nature with the cells demonstrating notable proliferation and matrix deposition activity. No adverse inflammatory response was observed in any of the implants from the two groups. Overall, the results emphasize the need to improve the technology in terms of altering the DBM and DCC concentrations, and tailoring the polymer degradation to these concentrations.
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Affiliation(s)
- Vineet Gupta
- Bioengineering Graduate Program, University of Kansas, Lawrence, Kansas, United States
| | - Dina V Lyne
- Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas, United States
| | - Amy D Laflin
- Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas, United States
| | - Taylor A Zabel
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, United States
| | - Marilyn Barragan
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, United States
| | - Joshua T Bunch
- Department of Orthopaedic Surgery, University of Kansas Medical Center, Kansas City, Kansas, United States
| | - Donna M Pacicca
- Division of Orthopaedic Surgery, Children's Mercy Hospital, Kansas City, Missouri, United States.,School of Medicine, University of Missouri-Kansas City, Kansas City, Missouri, United States
| | - Michael S Detamore
- Bioengineering Graduate Program, University of Kansas, Lawrence, Kansas, United States.,Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas, United States
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13
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Dai Z, Ronholm J, Tian Y, Sethi B, Cao X. Sterilization techniques for biodegradable scaffolds in tissue engineering applications. J Tissue Eng 2016; 7:2041731416648810. [PMID: 27247758 PMCID: PMC4874054 DOI: 10.1177/2041731416648810] [Citation(s) in RCA: 164] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 04/18/2016] [Indexed: 12/28/2022] Open
Abstract
Biodegradable scaffolds have been extensively studied due to their wide applications in biomaterials and tissue engineering. However, infections associated with in vivo use of these scaffolds by different microbiological contaminants remain to be a significant challenge. This review focuses on different sterilization techniques including heat, chemical, irradiation, and other novel sterilization techniques for various biodegradable scaffolds. Comparisons of these techniques, including their sterilization mechanisms, post-sterilization effects, and sterilization efficiencies, are discussed.
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Affiliation(s)
- Zheng Dai
- Department of Chemical and Biological Engineering, University of Ottawa, Ottawa, ON, Canada
| | - Jennifer Ronholm
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - Yiping Tian
- Department of Chemical and Biological Engineering, University of Ottawa, Ottawa, ON, Canada
| | - Benu Sethi
- Department of Chemical and Biological Engineering, University of Ottawa, Ottawa, ON, Canada
| | - Xudong Cao
- Department of Chemical and Biological Engineering, University of Ottawa, Ottawa, ON, Canada
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14
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Engineering and commercialization of human-device interfaces, from bone to brain. Biomaterials 2016; 95:35-46. [PMID: 27108404 DOI: 10.1016/j.biomaterials.2016.03.038] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 03/16/2016] [Accepted: 03/28/2016] [Indexed: 12/16/2022]
Abstract
Cutting edge developments in engineering of tissues, implants and devices allow for guidance and control of specific physiological structure-function relationships. Yet the engineering of functionally appropriate human-device interfaces represents an intractable challenge in the field. This leading opinion review outlines a set of current approaches as well as hurdles to design of interfaces that modulate transfer of information, i.a. forces, electrical potentials, chemical gradients and haptotactic paths, between endogenous and engineered body parts or tissues. The compendium is designed to bridge across currently separated disciplines by highlighting specific commonalities between seemingly disparate systems, e.g. musculoskeletal and nervous systems. We focus on specific examples from our own laboratories, demonstrating that the seemingly disparate musculoskeletal and nervous systems share common paradigms which can be harnessed to inspire innovative interface design solutions. Functional barrier interfaces that control molecular and biophysical traffic between tissue compartments of joints are addressed in an example of the knee. Furthermore, we describe the engineering of gradients for interfaces between endogenous and engineered tissues as well as between electrodes that physically and electrochemically couple the nervous and musculoskeletal systems. Finally, to promote translation of newly developed technologies into products, protocols, and treatments that benefit the patients who need them most, regulatory and technical challenges and opportunities are addressed on hand from an example of an implant cum delivery device that can be used to heal soft and hard tissues, from brain to bone.
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15
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Li W, Zheng Y, Zhao X, Ge Y, Chen T, Liu Y, Zhou Y. Osteoinductive Effects of Free and Immobilized Bone Forming Peptide-1 on Human Adipose-Derived Stem Cells. PLoS One 2016; 11:e0150294. [PMID: 26930062 PMCID: PMC4773240 DOI: 10.1371/journal.pone.0150294] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Accepted: 02/11/2016] [Indexed: 01/22/2023] Open
Abstract
Most synthetic polymeric materials currently used for bone tissue engineering lack specific signals through which cells can identify and interact with the surface, resulting in incompatibility and compromised osteogenic activity. Soluble inductive factors also have issues including a short half-live in vivo. Bone forming peptide-1 is a truncated peptide from the immature form of bone morphogenetic protein-7 (BMP-7) that displays higher osteogenic activity than full-length, mature BMP-7. In this study, we used a mussel-inspired immobilization strategy mediated by polymerization of dopamine to introduce recently discovered stimulators of bone forming peptide-1 (BFP-1) onto the surface of poly-lactic-co-glycolic acid (PLGA) substrate to form a biomaterial that overcomes these challenges. Human adipose-derived stem cells (hASCs), being abundant and easy accessible, were used to test the osteogenic activity of BFP-1 and the novel biomaterial. Under osteoinductive conditions, cells treated with both BFP-1 alone and BFP-1-coated biomaterials displayed elevated expression of the osteogenic markers alkaline phosphatase (ALP), osteocalcin (OC), and RUNX2. Furthermore, hASCs associated with poly-dopamine-assisted BFP-1-immobilized PLGA (pDA-BFP-1-PLGA) scaffolds promoted in vivo bone formation in nude mice. Our novel materials may hold great promise for future bone tissue engineering applications.
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Affiliation(s)
- Wenyue Li
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Yunfei Zheng
- Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China
| | - Xianghui Zhao
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Yanjun Ge
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Tong Chen
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Yunsong Liu
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Yongsheng Zhou
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, China
- National Engineering Lab for Digital and Material Technology of Stomatology, Peking University School and Hospital of Stomatology, Beijing, China
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16
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Sridharan B, Mohan N, Berkland CJ, Detamore MS. Material characterization of microsphere-based scaffolds with encapsulated raw materials. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2016; 63:422-8. [PMID: 27040236 DOI: 10.1016/j.msec.2016.02.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 12/14/2015] [Accepted: 02/13/2016] [Indexed: 10/22/2022]
Abstract
"Raw materials," or materials capable of serving both as building blocks and as signals, which are often but not always natural materials, are taking center stage in biomaterials for contemporary regenerative medicine. In osteochondral tissue engineering, a field leveraging the underlying bone to facilitate cartilage regeneration, common raw materials include chondroitin sulfate (CS) for cartilage and β-tricalcium phosphate (TCP) for bone. Building on our previous work with gradient scaffolds based on microspheres, here we delved deeper into the characterization of individual components. In the current study, the release of CS and TCP from poly(D, L-lactic-co-glycolic acid) (PLGA) microsphere-based scaffolds was evaluated over a time period of 4 weeks. Raw material encapsulated groups were compared to 'blank' groups and evaluated for surface topology, molecular weight, and mechanical performance as a function of time. The CS group may have led to increased surface porosity, and the addition of CS improved the mechanical performance of the scaffold. The finding that CS was completely released into the surrounding media by 4 weeks has a significant impact on future in vivo studies, given rapid bioavailability. The addition of TCP seemed to contribute to the rough external appearance of the scaffold. The current study provides an introduction to degradation patterns of homogenous raw material encapsulated scaffolds, providing characterization data to advance the field of microsphere-based scaffolds in tissue engineering.
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Affiliation(s)
| | - Neethu Mohan
- Division of Tissue Engineering and Regeneration Technologies, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
| | - Cory J Berkland
- Bioengineering Program, University of Kansas, Lawrence, KS, USA; Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS, USA; Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS, USA
| | - Michael S Detamore
- Bioengineering Program, University of Kansas, Lawrence, KS, USA; Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS, USA.
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17
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Mohan N, Gupta V, Sridharan BP, Mellott AJ, Easley JT, Palmer RH, Galbraith RA, Key VH, Berkland CJ, Detamore MS. Microsphere-based gradient implants for osteochondral regeneration: a long-term study in sheep. Regen Med 2015; 10:709-28. [PMID: 26418471 DOI: 10.2217/rme.15.38] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The microfracture technique for cartilage repair has limited ability to regenerate hyaline cartilage. AIM The current study made a direct comparison between microfracture and an osteochondral approach with microsphere-based gradient plugs. MATERIALS & METHODS The PLGA-based scaffolds had opposing gradients of chondroitin sulfate and β-tricalcium phosphate. A 1-year repair study in sheep was conducted. RESULTS The repair tissues in the microfracture were mostly fibrous and had scattered fissures with degenerative changes. Cartilage regenerated with the gradient plugs had equal or superior mechanical properties; had lacunated cells and stable matrix as in hyaline cartilage. CONCLUSION This first report of gradient scaffolds in a long-term, large animal, osteochondral defect demonstrated potential for equal or better cartilage repair than microfracture.
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Affiliation(s)
- Neethu Mohan
- Department of Chemical & Petroleum Engineering, University of Kansas, Lawrence, KS 66045, USA.,Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences & Technology, Trivandrum, Kerala 695011, India
| | - Vineet Gupta
- Bioengineering Graduate Program, University of Kansas, Lawrence, KS 66045, USA
| | | | - Adam J Mellott
- Department of Chemical & Petroleum Engineering, University of Kansas, Lawrence, KS 66045, USA
| | - Jeremiah T Easley
- Preclinical Surgical Research Laboratory, College of Veterinary Medicine & Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Ross H Palmer
- Preclinical Surgical Research Laboratory, College of Veterinary Medicine & Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | | | - Vincent H Key
- University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Cory J Berkland
- Department of Chemical & Petroleum Engineering, University of Kansas, Lawrence, KS 66045, USA.,Bioengineering Graduate Program, University of Kansas, Lawrence, KS 66045, USA.,Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66045, USA
| | - Michael S Detamore
- Department of Chemical & Petroleum Engineering, University of Kansas, Lawrence, KS 66045, USA.,Bioengineering Graduate Program, University of Kansas, Lawrence, KS 66045, USA
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Ott LM, Vu CH, Farris AL, Fox KD, Galbraith RA, Weiss ML, Weatherly RA, Detamore MS. Functional Reconstruction of Tracheal Defects by Protein-Loaded, Cell-Seeded, Fibrous Constructs in Rabbits. Tissue Eng Part A 2015; 21:2390-403. [PMID: 26094554 DOI: 10.1089/ten.tea.2015.0157] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Tracheal stenosis is a life-threatening disease and current treatments include surgical reconstruction with autologous rib cartilage and the highly complex slide tracheoplasty surgical technique. We propose using a sustainable implant, composed of a tunable, fibrous scaffold with encapsulated chondrogenic growth factor (transforming growth factor-beta3 [TGF-β3]) or seeded allogeneic rabbit bone marrow mesenchymal stromal cells (BMSCs). In vivo functionality of these constructs was determined by implanting them in induced tracheal defects in rabbits for 6 or 12 weeks. The scaffolds maintained functional airways in a majority of the cases, with the BMSC-seeded group having an improved survival rate and the Scaffold-only group having a higher occurrence of more patent airways as determined by microcomputed tomography. The BMSC group had a greater accumulation of inflammatory cells over the graft, while also exhibiting normal epithelium, subepithelium, and cartilage formation. Overall, it was concluded that a simple, acellular scaffold is a viable option for tracheal tissue engineering, with the intraoperative addition of cells being an optional variation to the scaffolds.
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Affiliation(s)
- Lindsey M Ott
- 1 Bioengineering Program, University of Kansas , Lawrence, Kansas
| | - Cindy H Vu
- 2 School of Medicine, University of Kansas , Kansas City, Kansas
| | - Ashley L Farris
- 3 Department of Molecular Biosciences, University of Kansas , Lawrence, Kansas
| | - Katrina D Fox
- 4 College of Veterinary Medicine, Kansas State University , Manhattan, Kansas
| | - Richard A Galbraith
- 5 Anatomic and Clinical Pathology, Lawrence Memorial Hospital , Lawrence, Kansas
| | - Mark L Weiss
- 4 College of Veterinary Medicine, Kansas State University , Manhattan, Kansas
| | - Robert A Weatherly
- 6 Section of Otolaryngology, Children's Mercy Hospital , Kansas City, Missouri
| | - Michael S Detamore
- 1 Bioengineering Program, University of Kansas , Lawrence, Kansas
- 7 Department of Chemical and Petroleum Engineering, University of Kansas , Lawrence, Kansas
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Sutherland AJ, Detamore MS. Bioactive Microsphere-Based Scaffolds Containing Decellularized Cartilage. Macromol Biosci 2015; 15:979-89. [PMID: 25821206 DOI: 10.1002/mabi.201400472] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 02/03/2015] [Indexed: 12/15/2022]
Abstract
The aim of this study was to fabricate mechanically functional microsphere-based scaffolds containing decellularized cartilage (DCC), with the hypothesis that this approach would induce chondrogenesis of rat bone marrow-derived mesenchymal stem cells (rBMSCs) in vitro. The DCC was derived from porcine articular cartilage and decellularized using a combination of physical and chemical methods. Four types of scaffolds were fabricated: poly(d,l-lactic-co-glycolic acid) (PLGA) only (negative control), TGF-β-encapsulated (positive control), PLGA surface coated with DCC, and DCC-encapsulated. These scaffolds were seeded with rBMSCs and cultured up to 6 weeks. The compressive modulus of the DCC-coated scaffolds prior to cell seeding was significantly lower than all other scaffold types. Gene expression was comparable between DCC-encapsulated and TGF-β-encapsulated groups. Notably, DCC-encapsulated scaffolds contained 70% higher glycosaminoglyan (GAG) content and 85% more hydroxyproline compared to the TGF-β group at week 3 (with baseline levels subtracted out from acellular DCC scaffolds). Certainly, bioactivity was demonstrated in eliciting a biosynthetic response from the cells with DCC, although true demonstration of chondrogenesis remained elusive under the prescribed conditions. Encapsulation of DCC appeared to lead to improved cell performance relative to coating with DCC, although this finding may be a dose-dependent observation. Overall, DCC introduced via microsphere-based scaffolds appears to be promising as a bioactive approach to cartilage regeneration, although additional studies will be required to conclusively demonstrate chondroinductivity.
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Affiliation(s)
- Amanda J Sutherland
- Bioengineering Graduate Program, University of Kansas, Lawrence, 66045, Kansas, USA
| | - Michael S Detamore
- Bioengineering Graduate Program, University of Kansas, Lawrence, 66045, Kansas, USA. .,Department of Chemical and Petroleum Engineering, University of Kansas, 4149 Learned Hall, 1530 W 15th St., Lawrence, 66045, Kansas, USA.
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Mohan N, Gupta V, Sridharan B, Sutherland A, Detamore MS. The potential of encapsulating "raw materials" in 3D osteochondral gradient scaffolds. Biotechnol Bioeng 2013; 111:829-41. [PMID: 24293388 DOI: 10.1002/bit.25145] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 10/16/2013] [Accepted: 11/01/2013] [Indexed: 12/12/2022]
Abstract
Scaffolds with continuous gradients in material composition and bioactive signals enable a smooth transition of properties at the interface. Components like chondroitin sulfate (CS) and bioactive glass (BG) in 3D scaffolds may serve as "raw materials" for synthesis of new extracellular matrix (ECM), and may have the potential to completely or partially replace expensive growth factors. We hypothesized that scaffolds with gradients of ECM components would enable superior performance of engineered constructs. Raw material encapsulation altered the appearance, structure, porosity, and degradation of the scaffolds. They allowed the scaffolds to better retain their 3D structure during culture and provided a buffering effect to the cells in culture. Following seeding of rat mesenchymal stem cells, there were several instances where glycosaminoglycan (GAG), collagen, or calcium contents were higher with the scaffolds containing raw materials (CS or BG) than with those containing transforming growth factor (TGF)-β3 or bone morphogenetic protein (BMP)-2. It was also noteworthy that a combination of both CS and TGF-β3 increased the secretion of collagen type II. Moreover, cells seeded in scaffolds containing opposing gradients of CS/TGF-β3 and BG/BMP-2 produced clear regional variations in the secretion of tissue-specific ECM. The study demonstrated raw materials have the potential to create a favorable microenvironment for cells; they can significantly enhance the synthesis of certain extracellular matrix (ECM) components when compared to expensive growth factors; either alone or in combination with growth factors they can enhance the secretion of tissue specific matrix proteins. Raw materials are promising candidates that can be used to either replace or be used in combination with growth factors. Success with raw materials in lieu of growth factors could have profound implications in terms of lower cost and faster regulatory approval for more rapid translation of regenerative medicine products to the clinic.
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Affiliation(s)
- Neethu Mohan
- Division of Tissue Engineering and Regeneration Technologies, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
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21
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Bhamidipati M, Sridharan B, Scurto AM, Detamore MS. Subcritical CO2 sintering of microspheres of different polymeric materials to fabricate scaffolds for tissue engineering. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2013; 33:4892-9. [PMID: 24094202 DOI: 10.1016/j.msec.2013.08.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 07/07/2013] [Accepted: 08/07/2013] [Indexed: 12/12/2022]
Abstract
The aim of this study was to use CO2 at sub-critical pressures as a tool to sinter 3D, macroporous, microsphere-based scaffolds for bone and cartilage tissue engineering. Porous scaffolds composed of ~200 μm microspheres of either poly(lactic-co-glycolic acid) (PLGA) or polycaprolactone (PCL) were prepared using dense phase CO2 sintering, which were seeded with rat bone marrow mesenchymal stromal cells (rBMSCs), and exposed to either osteogenic (PLGA, PCL) or chondrogenic (PLGA) conditions for 6 weeks. Under osteogenic conditions, the PLGA constructs produced over an order of magnitude more calcium than the PCL constructs, whereas the PCL constructs had far superior mechanical and structural integrity (125 times stiffer than PLGA constructs) at week 6, along with twice the cell content of the PLGA constructs. Chondrogenic cell performance was limited in PLGA constructs, perhaps as a result of the polymer degradation rate being too high. The current study represents the first long-term culture of CO2-sintered microsphere-based scaffolds, and has established important thermodynamic differences in sintering between the selected formulations of PLGA and PCL, with the former requiring adjustment of pressure only, and the latter requiring the adjustment of both pressure and temperature. Based on more straightforward sintering conditions and more favorable cell performance, PLGA may be the material of choice for microspheres in a CO2 sintering application, although a different PLGA formulation with the encapsulation of growth factors, extracellular matrix-derived nanoparticles, and/or buffers in the microspheres may be advantageous for achieving a more superior cell performance than observed here.
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