Passage Optimization of Superficial Zone Chondrocytes

• Anh Ho, Biological Sciences, University of Delaware

• Justin Parreno, Biological Sciences, Biomedical Engineering, University of Delaware

Passage Optimization of Superficial Zone Chondrocytes
Anh Ho, Thomas Manzoni, Justin Parreno
Articular cartilage has a limited ability for self-repair and any damage initiates degeneration leading to Osteoarthritis. Bioengineered cartilage holds promise in preventing Osteoarthritis progression from a small defect. Monolayer expanded (passaged) chondrocytes, harvested from full-thickness cartilage, are an FDA-approved cell source that has been used for bioengineering. However, our previous work has shown that monolayer expansion of full-thickness chondrocytes does not produce a robust superficial zone (SZ), which is critical in providing a frictionless environment for the movement of one cartilage surface over another. We determined that cell expansion limits the number of superficial zone cells (SZC) acquired by the end of culture due to poor attachment to, and slow proliferation of SZC on, polystyrene dishes. Additionally, the SZC that remains on dishes undergo dedifferentiation in culture. Therefore, it is necessary to optimize expansion methods to obtain adequate SZC. Previous studies showed that culture full-thickness chondrocytes on decellularized matrix-coated flasks (CellvoTM ChondroMatrix) can improve proliferation and reduce dedifferentiation. Here, we test the hypothesis that culturing SZC on ChondroMatrix will increase attachment, proliferation rate, and reduce SZC dedifferentiation. We isolated SZC from bovine joints and expanded them on polystyrene or ChondroMatrix flasks. We examined cell attachment, cell number expansion rate, and mRNA levels. As compared to polystyrene, when cultured on ChondroMatrix, SZC had greater attachment and proliferation rates. Furthermore, passaging SZC on ChondroMatrix reduced dedifferentiation molecule (collagen-I, tenascin-C) mRNA levels. While chondrogenic mRNA levels (collagen-II, aggrecan, and PRG4) were reduced, expression of SZ-specific molecule, clusterin, was maintained in SZC passaged on ChondroMatrix. Overall, the use of decellularized matrix improves SZC expansion. Future studies aim to determine if SZC passaged on ChondroMatrix can be stimulated to redifferentiate and produce a robust SZ in bioengineered cartilage.