The interplay between chondrocyte redifferentiation pellet size and oxygen concentration

Kul, Betul, Ghanavi, Parisa, Levett, Peter A., Lott, William B., Klein, Travis J., Cooper-White, Justin, Crawford, Ross, & Doran, Michael R. (2013) The interplay between chondrocyte redifferentiation pellet size and oxygen concentration. PLoS ONE, 8(3), e58865.

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Abstract

Chondrocytes dedifferentiate during ex vivo expansion on 2-dimensional surfaces. Aggregation of the expanded cells into 3-dimensional pellets, in the presence of induction factors, facilitates their redifferentiation and restoration of the chondrogenic phenotype. Typically 1×105–5×105 chondrocytes are aggregated, resulting in “macro” pellets having diameters ranging from 1–2 mm. These macropellets are commonly used to study redifferentiation, and recently macropellets of autologous chondrocytes have been implanted directly into articular cartilage defects to facilitate their repair. However, diffusion of metabolites over the 1–2 mm pellet length-scales is inefficient, resulting in radial tissue heterogeneity. Herein we demonstrate that the aggregation of 2×105 human chondrocytes into micropellets of 166 cells each, rather than into larger single macropellets, enhances chondrogenic redifferentiation. In this study, we describe the development of a cost effective fabrication strategy to manufacture a microwell surface for the large-scale production of micropellets. The thousands of micropellets were manufactured using the microwell platform, which is an array of 360×360 µm microwells cast into polydimethylsiloxane (PDMS), that has been surface modified with an electrostatic multilayer of hyaluronic acid and chitosan to enhance micropellet formation. Such surface modification was essential to prevent chondrocyte spreading on the PDMS. Sulfated glycosaminoglycan (sGAG) production and collagen II gene expression in chondrocyte micropellets increased significantly relative to macropellet controls, and redifferentiation was enhanced in both macro and micropellets with the provision of a hypoxic atmosphere (2% O2). Once micropellet formation had been optimized, we demonstrated that micropellets could be assembled into larger cartilage tissues. Our results indicate that micropellet amalgamation efficiency is inversely related to the time cultured as discreet microtissues. In summary, we describe a micropellet production platform that represents an efficient tool for studying chondrocyte redifferentiation and demonstrate that the micropellets could be assembled into larger tissues, potentially useful in cartilage defect repair.

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ID Code: 60682
Item Type: Journal Article
Refereed: Yes
Keywords: chondrocytes, three dimensional tissue culture, oxygen diffusion, tissue repair
DOI: 10.1371/journal.pone.0058865
ISSN: 1932-6203
Subjects: Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000)
Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > BIOCHEMISTRY AND CELL BIOLOGY (060100) > Cellular Interactions (incl. Adhesion Matrix Cell Wall) (060106)
Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > OTHER BIOLOGICAL SCIENCES (069900) > Biological Sciences not elsewhere classified (069999)
Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000)
Divisions: Current > Schools > School of Biomedical Sciences
Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Funding:
Copyright Owner: Copyright 2013 Kul et al.
Copyright Statement: This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Deposited On: 17 Jun 2013 00:59
Last Modified: 09 Apr 2014 12:21

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