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Gonzalez-Nolde S, Schweiger CJ, Davis EER, Manzoni TJ, Hussein SMI, Schmidt TA, Cone SG, Jay GD, Parreno J. The Actin Cytoskeleton as a Regulator of Proteoglycan 4. Cartilage 2024:19476035231223455. [PMID: 38183234 DOI: 10.1177/19476035231223455] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2024] Open
Abstract
OBJECTIVE The superficial zone (SZ) of articular cartilage is responsible for distributing shear forces for optimal cartilage loading and contributes to joint lubrication through the production of proteoglycan 4 (PRG4). PRG4 plays a critical role in joint homeostasis and is chondroprotective. Normal PRG4 production is affected by inflammation and irregular mechanical loading in post-traumatic osteoarthritis (PTOA). THe SZ chondrocyte (SZC) phenotype, including PRG4 expression, is regulated by the actin cytoskeleton in vitro. There remains a limited understanding of the regulation of PRG4 by the actin cytoskeleton in native articular chondrocytes. The filamentous (F)-actin cytoskeleton is a potential node in crosstalk between mechanical stimulation and cytokine activation and the regulation of PRG4 in SZCs, therefore developing insights in the regulation of PRG4 by actin may identify molecular targets for novel PTOA therapies. MATERIALS AND METHODS A comprehensive literature search on PRG4 and the regulation of the SZC phenotype by actin organization was performed. RESULTS PRG4 is strongly regulated by the actin cytoskeleton in isolated SZCs in vitro. Biochemical and mechanical stimuli have been characterized to regulate PRG4 and may converge upon actin cytoskeleton signaling. CONCLUSION Actin-based regulation of PRG4 in native SZCs is not fully understood and requires further elucidation. Understanding the regulation of PRG4 by actin in SZCs requires an in vivo context to further potential of leveraging actin arrangement to arthritic therapeutics.
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Temple-Wong MM, Raleigh AR, Frisbie DD, Sah RL, McIlwraith CW. Effects of an articular cartilage lubrication with a viscosupplement in vitro and in vivo following osteochondral fractures in horses. Am J Vet Res 2021; 82:611-618. [PMID: 34296945 DOI: 10.2460/ajvr.82.8.611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 11/20/2022]
Abstract
OBJECTIVE To assess whether the combination of hyaluronan, sodium chondroitin sulfate, and N-acetyl-d-glucosamine (HCSG) lubricates articular cartilage in vitro and modulates joint lubrication in vivo. ANIMALS 16 healthy adult horses. PROCEDURES The effects of HCSG injections on SF lubricant properties and joint health, immediately after injury and 2 weeks later, were analyzed by use an equine osteochondral fracture model of post-traumatic osteoarthritis (OA). Middle carpal joints of adult horses were randomly assigned to 1 of 4 surgical treatment groups as follows: normal nonsurgical group (n = 8), normal sham-surgical group (8), OA-induced surgical group with HCSG injection (8), or OA-induced surgical group with saline (0.9% NaCl) solution injection (8). Synovial fluid was aspirated periodically and analyzed for boundary lubrication function and lubricant molecules. At 17 days, joints were screened for gross pathological changes. RESULTS Induction of OA led to an impairment of SF lubrication function and diminished hyaluronan concentration in a time-dependent manner following surgery, with HCSG injection lessening these effects. Certain friction coefficients approached those of unaffected normal equine SF. Induction of OA also caused synovial hemorrhage at 17 days, which was lower in joints treated with HCSG. CONCLUSIONS AND CLINICAL RELEVANCE After induction of OA, equine SF lubricant function was impaired. Hyaluronan-sodium chondroitin sulfate-N-acetyl-d-glucosamine injection restored lubricant properties at certain time points and reduced pathological joint changes.
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Affiliation(s)
- Michele M Temple-Wong
- From the Department of Bioengineering and Institute of Engineering in Medicine-Center for Musculoskeletal Research, University of California-San Diego, La Jolla, CA 92093
| | - Aimee R Raleigh
- From the Department of Bioengineering and Institute of Engineering in Medicine-Center for Musculoskeletal Research, University of California-San Diego, La Jolla, CA 92093
| | - David D Frisbie
- Orthopaedic Research Center, C. Wayne McIlwraith Translational Medicine Institute, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523
| | - Robert L Sah
- From the Department of Bioengineering and Institute of Engineering in Medicine-Center for Musculoskeletal Research, University of California-San Diego, La Jolla, CA 92093
| | - C Wayne McIlwraith
- Orthopaedic Research Center, C. Wayne McIlwraith Translational Medicine Institute, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523
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Matheson A, Regmi SC, Martin-Alarcon L, Jay GD, Scott WM, Schmidt TA. Proteoglycan-4 and hyaluronan composition in synovial fluid and serum from clinical equine subjects: relationship to cartilage boundary lubrication and viscosity of synovial fluid. Connect Tissue Res 2021; 62:369-380. [PMID: 32306780 DOI: 10.1080/03008207.2020.1751140] [Citation(s) in RCA: 6] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Purpose: In experimental models of equine joint-injury and osteoarthritis synovial fluid (SF) composition (proteoglycan-4, hyaluronan) can vary, along with changes to SF mechanical function (lubrication, viscosity). The study hypotheses were a) clinical equine joint-injury and disease results in altered SF composition and diminished mechanical function, and b) serum composition (proteoglycan-4 or hyaluronan) changes concurrently. The objectives were to characterize composition (proteoglycan-4, hyaluronan), and function of SF and serum from normal horses compared to clinical groups: osteoarthritis, acute-joint-injury, and osteochondrosis.Materials and Methods: Equine samples of SF (from various joints) and blood were collected at the point-of-care. Proteoglycan-4 concentrations were measured by amplified-luminescence-proximity-assay and enzyme-linked-immunosorbent-assay in SF and serum, respectively. Molecular-weight of hyaluronan was characterized by agarose-gel-electrophoresis, and concentrations were measured by enzyme-linked-immunosorbent-assay kit. Biomechanical function of SF was characterized by an in vitro cartilage-on-cartilage friction test, and viscosity test.Results: SF proteoglycan-4 concentration increased in acute-joint-injury (1185 ± 276 versus normal 205 ± 106 µg/mL, µ± SEM, p < 0.01), with increased percentage of lower molecular-weight hyaluronan in acute-joint-injury and osteochondrosis. SF and serum proteoglycan-4 concentrations were correlated in normal horses (r2 = 0.85, p < 0.05), but not in clinical groups. Cartilage-lubricating ability was unchanged, although steady-shear viscosity of acute-joint-injury SF decreased from normal.Conclusion: Composition of SF from cases of equine acute-joint-injury changed; both proteoglycan-4 concentration and hyaluronan molecular-weight were altered, with decreased SF viscosity, but no associated changes to serum. Serum proteoglycan-4 and hyaluronan concentrations alone may not be useful biomarkers for equine joint-injury or disease.
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Affiliation(s)
- Austyn Matheson
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada
| | - Suresh C Regmi
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada
| | | | - Gregory D Jay
- Department of Emergency Medicine - Warren Alpert Medical School & School of Engineering, Brown University, Providence, RI, USA
| | - W Michael Scott
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada.,Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Tannin A Schmidt
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada.,Biomedical Engineering Department, University of Connecticut Health Center, Farmington, CT, USA
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Seekell RP, Lin K, Zhu Y. Dynamics of Confined Microgel Liquids: Weakened Spatial Confinement Effect by Microgel Particle Compliance. Langmuir 2021; 37:5299-5305. [PMID: 33886325 DOI: 10.1021/acs.langmuir.1c00363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Spatial confinement has a great impact on the structures and dynamics of interfacial molecular and polymer liquid films. Most prior research has focused on confined liquids of fixed material compliance and often treated them in approximation to the "hard-sphere" interaction model. In this study, we microscopically investigate the structural dynamics of highly deformable poly(N-isopropylacrylamide) (PNIPAM) microgels confined between two solid surfaces in comparison to that of nearly nondeformable microgels of the same chemistry. We observe that the mobility and structural relaxation of highly deformable PNIPAM microgels at an apparent volume fraction, ϕ = 0.49-0.70, show little change with the reduction of gap spacing, in stark contrast to confinement-induced dynamic retardation of "hard-sphere"-like stiff PNIPAM microgels. The critical gap spacing, defined as the onset of confinement effect to deviate from the bulk behavior, is found to be approximately 17-22 particle layers for highly deformable microgels of ϕ = 0.56-0.70, much smaller than that of approximately 40 particle layers or larger for stiff microgels or model "hard-sphere" colloidal liquids of similar ϕ. Additionally, we observe no evident confinement-enhanced structural reorganization of deformable microgels near the confining surfaces when gap spacing approaches the critical gap spacing. Microgel deformation upon strong confinement is attributed to the disrupted confinement-induced ordering of confined microgels. Hence, it is clearly indicated that spatial confinement exhibits a much weaker effect on highly compliant microgel particles than stiff ones, resulting in a significantly less reduction in microgel interfacial dynamics. It therefore gives insights into the molecular design of polymeric thin films of variable compliance to control friction and lubrication.
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Affiliation(s)
- Raymond P Seekell
- LiquiGlide, Inc., 75 Sidney Street, Cambridge, Massachusetts 02139, United States
| | - Kehua Lin
- Department of Chemical Engineering and Materials Science, Wayne State University, 5050 Anthony Wayne Drive, Detroit, Michigan 48202, United States
| | - Yingxi Zhu
- Department of Chemical Engineering and Materials Science, Wayne State University, 5050 Anthony Wayne Drive, Detroit, Michigan 48202, United States
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Ji X, Ito A, Nakahata A, Nishitani K, Kuroki H, Aoyama T. Effects of in vivo cyclic compressive loading on the distribution of local Col2 and superficial lubricin in rat knee cartilage. J Orthop Res 2021; 39:543-552. [PMID: 32716572 DOI: 10.1002/jor.24812] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 05/20/2020] [Accepted: 07/09/2020] [Indexed: 02/04/2023]
Abstract
This study aimed to examine the effects of an episode of in vivo cyclic loading on rat knee articular cartilage (AC) under medium-term observation, while also investigating relevant factors associated with the progression of post-traumatic osteoarthritis (PTOA). Twelve-week-old Wistar rats underwent one episode comprising 60 cycles of 20 N or 50 N dynamic compression on the right knee joint. Spatiotemporal changes in the AC after loading were evaluated using histology and immunohistochemistry at 3 days and 1, 2, 4, and 8 weeks after loading (n = 6 for each condition). Chondrocyte vitality was assessed at 1, 3, 6, and 12 hours after loading (n = 2 for each condition). A localized AC lesion on the lateral femoral condyle was confirmed in all subjects. The surface and intermediate cartilage in the affected area degenerated after loading, but the calcified cartilage remained intact. Expression of type II collagen in the lesion cartilage was upregulated after loading, whereas the superficial lubricin layer was eroded in response to cyclic compression. However, the distribution of superficial lubricin gradually recovered to the normal level 4 weeks after loading-induced injury. We confirmed that 60 repetitions of cyclic loading exceeding 20 N could result in cartilage damage in the rat knee. Endogenous repairs in well-structured joints work well to rebuild protective layers on the lesion cartilage surface, which may be the latent factor delaying the progression of PTOA.
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Affiliation(s)
- Xiang Ji
- Department of Development and Rehabilitation of Motor Function, Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Akira Ito
- Department of Motor Function Analysis, Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Akihiro Nakahata
- Department of Motor Function Analysis, Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kohei Nishitani
- Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiroshi Kuroki
- Department of Motor Function Analysis, Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Tomoki Aoyama
- Department of Development and Rehabilitation of Motor Function, Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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Feeney E, Galesso D, Secchieri C, Oliviero F, Ramonda R, Bonassar LJ. Inflammatory and Noninflammatory Synovial Fluids Exhibit New and Distinct Tribological Endotypes. J Biomech Eng 2020; 142:1084761. [DOI: 10.1115/1.4047628] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Indexed: 12/31/2022]
Abstract
Abstract
Inferior synovial lubrication is a hallmark of osteoarthritis (OA), and synovial fluid (SF) lubrication and composition are variable among OA patients. Hyaluronic acid (HA) viscosupplementation is a widely used therapy for improving SF viscoelasticity and lubrication, but it is unclear how the effectiveness of HA viscosupplements varies with arthritic endotype. The objective of this study was to investigate the effects of the HA viscosupplement, Hymovis®, on the lubricating properties of diseased SF from patients with noninflammatory OA and inflammatory arthritis (IA). The composition (cytokine, HA, and lubricin concentrations) of the SF was measured as well as the mechanical properties (rheology, tribology) of the SF alone and in a 1:1 mixture with the HA viscosupplement. Using rotational rheometry, no difference in SF viscosity was detected between disease types, and the addition of HA significantly increased all fluids' viscosities. In noninflammatory OA SF, friction coefficients followed a typical Stribeck pattern, and their magnitude was decreased by the addition of HA. While some of the IA SF also showed typical Stribeck behavior, a subset showed more erratic behavior with highly variable and larger friction coefficients. Interestingly, this aberrant behavior was not eliminated by the addition of HA, and it was associated with low concentrations of lubricin. Aberrant SF exhibited significantly lower effective viscosities compared to noninflammatory OA and IA SF with typical tribological behavior. Collectively, these results suggest that different endotypes of arthritis exist with respect to lubrication, which may impact the effectiveness of HA viscosupplements in reducing friction.
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Affiliation(s)
- Elizabeth Feeney
- Nancy and Peter Meinig School of Biomedical Engineering, Cornell University, Weill Hall 152 526 Campus Road, Ithaca, NY 14853
| | - Devis Galesso
- Fidia Farmaceutici S.p.A, Via Ponte della Fabbrica 3/A, Abano Terme, Padua 35031, Italy
| | - Cynthia Secchieri
- Fidia Farmaceutici S.p.A, Via Ponte della Fabbrica 3/A, Abano Terme, Padua 35031, Italy
| | - Francesca Oliviero
- Rheumatology Unit, Department of Medicine-DIMED, University of Padua, Via Giustiniani, 2, Padua 35128, Italy
| | - Roberta Ramonda
- Rheumatology Unit, Department of Medicine-DIMED, University of Padua, Via Giustiniani, 2, Padua 35128, Italy
| | - Lawrence J. Bonassar
- Nancy and Peter Meinig School of Biomedical Engineering, Cornell University, Weill Hall 152, 526 Campus Road, Ithaca, NY 14853; Sibley School of Mechanical and Aerospace Engineering, Cornell University, Weill Hall 149, 526 Campus Road, Ithaca, NY 14853
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Peal BT, Gagliardi R, Su J, Fortier LA, Delco ML, Nixon AJ, Reesink HL. Synovial fluid lubricin and hyaluronan are altered in equine osteochondral fragmentation, cartilage impact injury, and full-thickness cartilage defect models. J Orthop Res 2020; 38:1826-1835. [PMID: 31965593 PMCID: PMC7354223 DOI: 10.1002/jor.24597] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 11/21/2019] [Accepted: 01/13/2020] [Indexed: 02/04/2023]
Abstract
The objectives of this study were to evaluate temporal changes in lubricin, hyaluronan (HA), and HA molecular weight (MW) distributions in three distinct models of equine joint injury affecting the carpal (wrist), tarsal (ankle), and femoropatellar (knee) joints. To establish ranges for lubricin, HA, and HA MW distributions across multiple joints, we first evaluated clinically healthy, high-motion equine joints. Synovial fluid was collected from high-motion joints in horses without clinical signs of joint disease (n = 11 horses, 102 joints) and from research horses undergoing carpal osteochondral fragmentation (n = 8), talar cartilage impact injury (n = 7), and femoral trochlear ridge full-thickness cartilage injury (n = 22) prior to and following arthroscopically induced joint injury. Lubricin and HA concentrations were measured via enzyme-linked immunosorbent assays, and gel electrophoresis was performed to evaluate HA MW distributions. Synovial fluid parameters were analyzed via linear regression models, revealing that lubricin and HA concentrations were conserved across healthy, high-motion joints. Lubricin concentrations increased post-injury in all osteoarthritis models (carpal fragmentation P = .001; talar impact P < .001; femoral trochlear ridge cartilage defect P = .03). Sustained loss of HA was noted post-arthroscopy following carpal osteochondral fragmentation (P < .0001) and talar impact injury (P < .001). Lubricin may be elevated to compensate for the loss of HA and to protect cartilage post-injury. Further investigation into the mechanisms regulating lubricin and HA following joint injury and their effects on joint homeostasis is warranted, including whether lubricin has value as a biomarker for post-traumatic osteoarthritis.
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Affiliation(s)
- Bridgette T. Peal
- Department of Clinical Sciences, College of Veterinary
Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853 USA
| | - Rachel Gagliardi
- Department of Clinical Sciences, College of Veterinary
Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853 USA
| | - Jin Su
- Department of Clinical Sciences, College of Veterinary
Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853 USA
| | - Lisa A. Fortier
- Department of Clinical Sciences, College of Veterinary
Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853 USA
| | - Michelle L. Delco
- Department of Clinical Sciences, College of Veterinary
Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853 USA
| | - Alan J. Nixon
- Department of Clinical Sciences, College of Veterinary
Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853 USA
| | - Heidi L. Reesink
- Department of Clinical Sciences, College of Veterinary
Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853 USA
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Feeney E, Peal BT, Inglis JE, Su J, Nixon AJ, Bonassar LJ, Reesink HL. Temporal changes in synovial fluid composition and elastoviscous lubrication in the equine carpal fracture model. J Orthop Res 2019; 37:1071-1079. [PMID: 30859611 PMCID: PMC6768400 DOI: 10.1002/jor.24281] [Citation(s) in RCA: 10] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 02/20/2019] [Indexed: 02/04/2023]
Abstract
The objective of this study was to examine temporal variations in synovial fluid composition and lubrication following articular fracture. Post-traumatic osteoarthritis (PTOA) was induced by creating an osteochondral fracture in the middle carpal joint of four horses while the contralateral limb served as a sham-operated control. Horses were exercised on a high-speed treadmill, and synovial fluid was collected pre-operatively and at serial timepoints until 75 days post-operatively. Lubricin and hyaluronic acid (HA) concentrations were measured using sandwich ELISAs, and the molecular weight distribution of HA was analyzed via gel electrophoresis. Synovial fluid viscosity and cartilage friction coefficients across all modes of lubrication were measured on days 0, 19, 33, and 61 using a commercial rheometer and a custom tribometer, respectively. HA concentrations were significantly decreased post-operatively, and high molecular weight HA (>6.1MDa) did not recover to pre-operative values by the study termination at day 75. Lubricin concentrations increased after surgery to a greater extent in the OA as compared to sham-operated limbs. Viscosity was significantly reduced after surgery. While boundary and elastoviscous mode friction coefficients did not vary, the transition number, representing the shift between these modes, was lower. Although more pronounced in the OA limbs, similar derangements in HA, HA molecular weight distribution, viscosity, and transition number were observed in the sham-operated limbs, which may be explained by synovial fluid washout during arthroscopy. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.
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Affiliation(s)
- Elizabeth Feeney
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York
| | - Bridgette T. Peal
- Cornell University College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Jacqueline E. Inglis
- Cornell University College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Jin Su
- Cornell University College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Alan J. Nixon
- Cornell University College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Lawrence J. Bonassar
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York,Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York
| | - Heidi L. Reesink
- Cornell University College of Veterinary Medicine, Cornell University, Ithaca, New York
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Salinas EY, Hu JC, Athanasiou K. A Guide for Using Mechanical Stimulation to Enhance Tissue-Engineered Articular Cartilage Properties. Tissue Eng Part B Rev 2018; 24:345-358. [PMID: 29562835 DOI: 10.1089/ten.teb.2018.0006] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The use of tissue-engineered articular cartilage (TEAC) constructs has the potential to become a powerful treatment option for cartilage lesions resulting from trauma or early stages of pathology. Although fundamental tissue-engineering strategies based on the use of scaffolds, cells, and signals have been developed, techniques that lead to biomimetic AC constructs that can be translated to in vivo use are yet to be fully confirmed. Mechanical stimulation during tissue culture can be an effective strategy to enhance the mechanical, structural, and cellular properties of tissue-engineered constructs toward mimicking those of native AC. This review focuses on the use of mechanical stimulation to attain and enhance the properties of AC constructs needed to translate these implants to the clinic. In vivo, mechanical loading at maximal and supramaximal physiological levels has been shown to be detrimental to AC through the development of degenerative changes. In contrast, multiple studies have revealed that during culture, mechanical stimulation within narrow ranges of magnitude and duration can produce anisotropic, mechanically robust AC constructs with high cellular viability. Significant progress has been made in evaluating a variety of mechanical stimulation techniques on TEAC, either alone or in combination with other stimuli. These advancements include determining and optimizing efficacious loading parameters (e.g., duration and frequency) to yield improvements in construct design criteria, such as collagen II content, compressive stiffness, cell viability, and fiber organization. With the advancement of mechanical stimulation as a potent strategy in AC tissue engineering, a compendium detailing the results achievable by various stimulus regimens would be of great use for researchers in academia and industry. The objective is to list the qualitative and quantitative effects that can be attained when direct compression, hydrostatic pressure, shear, and tensile loading are used to tissue-engineer AC. Our goal is to provide a practical guide to their use and optimization of loading parameters. For each loading condition, we will also present and discuss benefits and limitations of bioreactor configurations that have been used. The intent is for this review to serve as a reference for including mechanical stimulation strategies as part of AC construct culture regimens.
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Affiliation(s)
- Evelia Y Salinas
- Biomedical Engineering Department, University of California , Irvine, California
| | - Jerry C Hu
- Biomedical Engineering Department, University of California , Irvine, California
| | - Kyriacos Athanasiou
- Biomedical Engineering Department, University of California , Irvine, California
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Waller KA, Chin KE, Jay GD, Zhang LX, Teeple E, McAllister S, Badger GJ, Schmidt TA, Fleming BC. Intra-articular Recombinant Human Proteoglycan 4 Mitigates Cartilage Damage After Destabilization of the Medial Meniscus in the Yucatan Minipig. Am J Sports Med 2017; 45:1512-1521. [PMID: 28129516 PMCID: PMC5453820 DOI: 10.1177/0363546516686965] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Lubricin, or proteoglycan 4 (PRG4), is a glycoprotein responsible for joint boundary lubrication. PRG4 has been shown previously to be down-regulated after traumatic joint injury such as a meniscal tear. Preliminary evidence suggests that intra-articular injection of PRG4 after injury will reduce cartilage damage in rat models of surgically induced posttraumatic osteoarthritis. OBJECTIVE To determine the efficacy of intra-articular injection of full-length recombinant human lubricin (rhPRG4) for reducing cartilage damage after medial meniscal destabilization (DMM) in a preclinical large animal model. STUDY DESIGN Controlled laboratory study. METHODS Unilateral DMM was performed in 29 Yucatan minipigs. One week after DMM, animals received 3 weekly intra-articular injections (3 mL per injection): (1) rhPRG4 (1.3 mg/mL; n = 10); (2) rhPRG4+hyaluronan (1.3 mg/mL rhPRG4 and 3 mg/mL hyaluronan [~950 kDA]; n = 10); and (3) phosphate-buffered saline (PBS; n = 9). Hindlimbs were harvested 26 weeks after surgery. Cartilage integrity was evaluated by use of macroscopic (India ink) and microscopic (safranin O-fast green and hematoxylin and eosin) scoring systems. Secondary outcomes evaluated via enzyme-linked immunosorbent assay (ELISA) included PRG4 levels in synovial fluid, carboxy-terminal telepeptide of type II collagen (CTX-II) concentrations in urine and serum, and interleukin 1β (IL-1β) levels in synovial fluid and serum. RESULTS The rhPRG4 group had significantly less macroscopic cartilage damage in the medial tibial plateau compared with the PBS group ( P = .002). No difference was found between the rhPRG4+hyaluronan and PBS groups ( P = .23). However, no differences in microscopic damage scores were observed between the 3 groups ( P = .70). PRG4 production was elevated in the rhPRG4 group synovial fluid compared with the PBS group ( P = .033). The rhPRG4 group presented significantly lower urinary CTX-II levels, but not serum levels, when compared with the PBS ( P = .013) and rhPRG4+hyaluronan ( P = .011) groups. In serum and synovial fluid, both rhPRG4 ( P = .006; P = .017) and rhPRG4+hyaluronan groups ( P = .009; P = .03) presented decreased IL-1β levels. CONCLUSION All groups exhibited significant cartilage degeneration after DMM surgery. However, animals treated with rhPRG4 had the least amount of cartilage damage and less inflammation, providing evidence that intra-articular injections of rhPRG4 may slow the progression of posttraumatic osteoarthritis. CLINICAL RELEVANCE Patients with meniscal trauma are at high risk for posttraumatic osteoarthritis. This study demonstrates that an intra-articular injection regimen of rhPRG4 may attenuate cartilage damage after meniscal injury.
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Affiliation(s)
- Kimberly A. Waller
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI
| | - Kaitlyn E. Chin
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI
| | - Gregory D. Jay
- Department of Emergency Medicine, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI,School of Engineering, Brown University, Providence, RI
| | - Ling X. Zhang
- Department of Emergency Medicine, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI
| | - Erin Teeple
- Department of Occupational and Environmental Medicine, Harvard School of Public Health, Boston, MA,Department of Orthopedic Surgery, Brigham and Women's Hospital, Boston, MA
| | - Scott McAllister
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI
| | - Gary J. Badger
- Department of Medical Biostatistics, University of Vermont, Burlington, VT
| | - Tannin A. Schmidt
- Faculty of Kinesiology & Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada
| | - Braden C. Fleming
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI,School of Engineering, Brown University, Providence, RI
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Larson KM, Zhang L, Elsaid KA, Schmidt TA, Fleming BC, Badger GJ, Jay GD. Reduction of friction by recombinant human proteoglycan 4 in IL-1α stimulated bovine cartilage explants. J Orthop Res 2017; 35:580-589. [PMID: 27411036 PMCID: PMC5957283 DOI: 10.1002/jor.23367] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 07/02/2016] [Indexed: 02/04/2023]
Abstract
A boundary lubricant attaches and protects sliding bearing surfaces by preventing interlocking asperity-asperity contact. Proteoglycan-4 (PRG4) is a boundary lubricant found in the synovial fluid that provides chondroprotection to articular surfaces. Inflammation of the diarthrodial joint modulates local PRG4 concentration. Thus, we measured the effects of inflammation, with Interleukin-1α (IL-1α) incubation, upon boundary lubrication and PRG4 expression in bovine cartilage explants. We further aimed to determine whether the addition of exogenous human recombinant PRG4 (rhPRG4) could mitigate the effects of inflammation on boundary lubrication and PRG4 expression in vitro. Cartilage explants, following a 7 day incubation with IL-1α, were tested in a disc-on-disc configuration using either rhPRG4 or saline (PBS control) as a lubricant. Following mechanical testing, explants were studied immunohistochemically or underwent RNA extraction for real-time polymerase chain reaction (RT-PCR). We found that static coefficient of friction (COF) significantly decreased to 0.14 ± 0.065 from 0.21 ± 0.059 (p = 0.014) in IL-1α stimulated explants lubricated with rhPRG4, as compared to PBS. PRG4 expression was significantly up regulated from 30.8 ± 19 copies in control explants lubricated with PBS to 3330 ± 1760 copies in control explants lubricated with rhPRG4 (p < 0.001). Explants stimulated with IL-1α displayed no increase in PRG4 expression upon lubrication with rhPRG4, but with PBS as the lubricant, IL-1α stimulation significantly increased PRG4 expression compared to the control condition from 30.8 ± 19 copies to 401 ± 340 copies (p = 0.015). Overall, these data suggest that exogenous rhPRG4 may provide a therapeutic option for reducing friction in transient inflammatory conditions and increasing PRG4 expression. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:580-589, 2017.
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Affiliation(s)
- Katherine M. Larson
- Center for Biomedical Engineering and School of Engineering, Brown University, Providence, RI, USA
| | - Ling Zhang
- Emergency Medicine Research Laboratory, Department of Emergency Medicine, Rhode Island Hospital, Providence, RI, USA
| | - Khaled A. Elsaid
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, USA
| | - Tannin A. Schmidt
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada,Schulich School of Engineering, University of Calgary, Calgary, AB, Canada
| | - Braden C. Fleming
- Center for Biomedical Engineering and School of Engineering, Brown University, Providence, RI, USA,Bioengineering Laboratory, Department of Orthopaedics, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI, USA
| | - Gary J. Badger
- Department of Medical Biostatistics, University of Vermont, Burlington, VT, USA
| | - Gregory D. Jay
- Center for Biomedical Engineering and School of Engineering, Brown University, Providence, RI, USA,Emergency Medicine Research Laboratory, Department of Emergency Medicine, Rhode Island Hospital, Providence, RI, USA,Department of Emergency Medicine, Warren Alpert Medical School of Brown University, Providence, RI, USA
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12
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Barton KI, Shekarforoush M, Heard BJ, Sevick JL, Vakil P, Atarod M, Martin R, Achari Y, Hart DA, Frank CB, Shrive NG. Use of pre-clinical surgically induced models to understand biomechanical and biological consequences of PTOA development. J Orthop Res 2017; 35:454-465. [PMID: 27256202 DOI: 10.1002/jor.23322] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 05/27/2016] [Indexed: 02/04/2023]
Abstract
Post-traumatic osteoarthritis (PTOA) development is often observed following traumatic knee injuries involving key stabilising structures such as the cruciate ligaments or the menisci. Both biomechanical and biological alterations that follow knee injuries have been implicated in PTOA development, although it has not been possible to differentiate clearly between the two causal factors. This review critically examines the outcomes from pre-clinical lapine and ovine injury models arising in the authors' laboratories and differing in severity of PTOA development and progression. Specifically, we focus on how varying severity of knee injuries influence the subsequent alterations in kinematics, kinetics, and biological outcomes. The immediate impact of injury on the lubrication capacity of the joint is examined in the context of its influence on biomechanical alterations, thus linking the biological changes to abnormal kinematics, leading to a focus on the potential areas for interventions to inhibit or prevent development of the disease. We believe that PTOA results from altered cartilage surface interactions where biological and biomechanical factors intersect, and mitigating acute joint inflammation may be critical to prolonging PTOA development. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:454-465, 2017.
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Affiliation(s)
- Kristen I Barton
- McCaig Institute for Bone & Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Mehdi Shekarforoush
- McCaig Institute for Bone & Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Schulich School of Engineering, University of Calgary, Calgary, AB, Canada
| | - Bryan J Heard
- McCaig Institute for Bone & Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - John L Sevick
- McCaig Institute for Bone & Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Schulich School of Engineering, University of Calgary, Calgary, AB, Canada
| | - Paria Vakil
- McCaig Institute for Bone & Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Schulich School of Engineering, University of Calgary, Calgary, AB, Canada
| | - Mohammad Atarod
- McCaig Institute for Bone & Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Schulich School of Engineering, University of Calgary, Calgary, AB, Canada
| | - Ryan Martin
- McCaig Institute for Bone & Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Section of Orthopaedics, University of Calgary, Foothills Hospital, Calgary, Alberta, Canada
| | - Yamini Achari
- McCaig Institute for Bone & Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - David A Hart
- McCaig Institute for Bone & Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Cyril B Frank
- McCaig Institute for Bone & Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Nigel G Shrive
- McCaig Institute for Bone & Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Schulich School of Engineering, University of Calgary, Calgary, AB, Canada
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13
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Shekhawat VK, Schmid TM, Pennekamp PH, Pacione CA, Chubinskaya S, Wimmer MA. Implications of trauma and subsequent articulation on the release of Proteoglycan-4 and tissue response in adult human ankle cartilage. J Orthop Res 2017; 35:667-676. [PMID: 27551813 DOI: 10.1002/jor.23397] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 08/12/2016] [Indexed: 02/04/2023]
Abstract
The purpose of this study was to investigate the effects of trauma and subsequent articulation on adult human ankle cartilage subjected to an injurious impact. Trauma was initiated through impaction on talar cartilage explants. Articulation and loading were applied in a joint bioreactor over 5 consecutive days. The early (24 h) effects of impaction included a reduced chondrocytes viability (51% vs. 81% for non-impacted; p = 0.03), increased levels of apoptosis (43% vs. 27%; p = 0.03), and an increase in the histopathology score (4.4 vs. 1.7; p = 0.02) as compared to non-impacted cartilage explants. One of the key findings was that damage also stimulated the PRG4 release (2.2 vs. 1.5 μg/ml). Subsequent articulation for 5 days did not lead to further changes in tissue histopathology and cell viability, neither for injured nor non-injured samples. However, articulation led to an increased apoptosis in the injured samples (p = 0.03 for the interaction term). Articulation also caused a significant increase of PG/GAG release into the culture medium (p = 0.04) for both injured and non-injured samples; however, the synthesis of PG was not affected by articulation (p = 0.45) though the PG synthesis was higher in injured samples (p < 0.01). With regard to the PRG4 release, impacted samples continued to show higher amounts (p = 0.01), adding articulation led to a reduction (p = 0.02). The current study demonstrated that adult human talar cartilage increases both the PRG4 release and biosynthetic activity as an immediate cellular response to injury. Articulation played a less contributing role to biosynthesis and remodeling, behaving mostly neutral, in that no further damage emerged. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:667-676, 2017.
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Affiliation(s)
- Vivek K Shekhawat
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois
| | - Thomas M Schmid
- Department of Biochemistry, Rush University Medical Center, Chicago, Illinois
| | - Peter H Pennekamp
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois
| | - Carol A Pacione
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois
| | - Susan Chubinskaya
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois.,Department of Pediatrics, Rush University Medical Center, Chicago, Illinois
| | - Markus A Wimmer
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois.,Department of Biochemistry, Rush University Medical Center, Chicago, Illinois
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Reesink H, Watts A, Mohammed H, Jay G, Nixon A. Lubricin/proteoglycan 4 increases in both experimental and naturally occurring equine osteoarthritis. Osteoarthritis Cartilage 2017; 25:128-137. [PMID: 27498214 PMCID: PMC5489058 DOI: 10.1016/j.joca.2016.07.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 07/25/2016] [Accepted: 07/28/2016] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The goals of this study were (1) to quantify proteoglycan 4 (PRG4) gene expression; (2) to assess lubricin immunostaining; and (3) to measure synovial fluid lubricin concentrations in clinical and experimental models of equine carpal osteoarthritis (OA). DESIGN Lubricin synovial fluid concentrations and cartilage and synovial membrane PRG4 expression were analyzed in research horses undergoing experimental OA induction (n = 8) and in equine clinical patients with carpal OA (n = 58). Lubricin concentrations were measured using a custom sandwich enzyme-linked immunosorbent assay, and PRG4 expression was quantified using qRT-PCR. Lubricin immunostaining was assessed in synovial membrane and osteochondral sections in the experimental model. RESULTS Lubricin concentrations increased in synovial fluid following induction of OA, peaking at 21 days post-operatively in OA joints vs sham-operated controls (331 ± 69 μg/mL vs 110 ± 19 μg/mL, P = 0.001). Lubricin concentrations also increased in horses with naturally occurring OA as compared to control joints (152 ± 32 μg/mL vs 68 ± 4 μg/mL, P = 0.003). Synovial membrane PRG4 expression increased nearly 2-fold in naturally occurring OA (P = 0.003), whereas cartilage PRG4 expression decreased 2.5-fold (P = 0.025). Lubricin immunostaining was more pronounced in synovial membrane from OA joints as compared to controls, with intense lubricin localization to sites of cartilage damage. CONCLUSIONS Although PRG4 gene expression decreases in OA cartilage, synovial membrane PRG4 expression, synovial fluid lubricin concentrations and lubricin immunostaining all increase in an equine OA model. Lubricin may be elevated to protect joints from post-traumatic OA.
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Affiliation(s)
- H.L. Reesink
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA,Address correspondence and reprint requests to: H.L. Reesink, Department of Clinical Sciences, Cornell University, Ithaca, NY 14853, USA. Fax: 1-607-253-3787. (A.J. Nixon)
| | - A.E. Watts
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - H.O. Mohammed
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - G.D. Jay
- Department of Emergency Medicine, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA,Department of Engineering, Brown University, Providence, RI 12903, USA
| | - A.J. Nixon
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA,Address correspondence and reprint requests to: A.J. Nixon, Department of Clinical Sciences, Cornell University, Ithaca, NY 14853, USA. Fax: 1-607-253-3787, (H.L. Reesink)
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15
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Abubacker S, Ponjevic D, Ham HO, Messersmith PB, Matyas JR, Schmidt TA. Effect of disulfide bonding and multimerization on proteoglycan 4's cartilage boundary lubricating ability and adsorption. Connect Tissue Res 2016; 57:113-23. [PMID: 26631309 PMCID: PMC4857611 DOI: 10.3109/03008207.2015.1113271] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE The objectives of this study were to assess the cartilage boundary lubricating ability of (1) nonreduced (NR) disulfide-bonded proteoglycan 4 (PRG4) multimers versus PRG4 monomers and (2) NR versus reduced and alkylated (R/A) PRG4 monomers and to assess (3) the ability of NR PRG4 multimers versus monomers to adsorb to an articular cartilage surface. MATERIALS AND METHODS PRG4 was separated into two preparations, PRG4 multimer enriched (PRG4Multi+) and PRG4 multimer deficient (PRG4Multi-), using size exclusion chromatography (SEC) and characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The cartilage boundary lubricating ability of PRG4Multi+ and PRG4Multi- was compared at a physiological concentration (450 μg/mL) and assessed over a range of concentrations (45, 150, and 450 μg/mL). R/A and NR PRG4Multi- were evaluated at 450 μg/mL. Immunohistochemistry with anti-PRG4 antibody 4D6 was performed to visualize the adsorption of PRG4 preparations to the surface of articular cartilage explants. RESULTS Separation into enriched populations of PRG4Multi+ and PRG4Multi- was achieved using SEC and was confirmed by SDS-PAGE. PRG4Multi+ and PRG4Multi- both functioned as effective friction-reducing cartilage boundary lubricants at 450 μg/mL, with PRG4Multi+ being more effective than PRG4Multi-. PRG4Multi+ lubricated in a dose-dependent manner, however, PRG4Multi- did not. R/A PRG4Multi- lubricated similar to NR PRG4Multi-. PRG4-containing solutions showed 4D6 immunoreactivity at the articular surface; the immunoreactive intensity of PRG4Multi+ appeared to be similar to SF, whereas PRG4Multi- appeared to have less intensity. CONCLUSIONS These results demonstrate that the intermolecular disulfide-bonded multimeric structure of PRG4 is important for its ability to adsorb to a cartilage surface and function as a boundary lubricant. These findings contribute to a greater understanding of the molecular basis of cartilage boundary lubrication of PRG4. Elucidating the PRG4 structure-lubrication function relationship will further contribute to the understanding of PRG4's role in diarthrodial joint homeostasis and disease.
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Affiliation(s)
- Saleem Abubacker
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada.,McCaig Institute of Bone and Joint Health, University of Calgary, Calgary, AB, Canada
| | - Dragana Ponjevic
- McCaig Institute of Bone and Joint Health, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Hyun O. Ham
- Biomedical Engineering Department, Northwestern University, Evanston, IL, USA
| | - Phillip B. Messersmith
- Biomedical Engineering Department, Northwestern University, Evanston, IL, USA.,Departments of Bioengineering and Materials Science and Engineering Department, University of California, Berkeley, CA, USA
| | - John R. Matyas
- McCaig Institute of Bone and Joint Health, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Tannin A. Schmidt
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada.,McCaig Institute of Bone and Joint Health, University of Calgary, Calgary, AB, Canada.,Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
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