Mechanical stimulation of TMJ condylar chondrocytes encapsulated in PEG hydrogels

Temporomandibular joint (TMJ) disorders are most commonly associated with TMJ disc dislocation and osteoarthritis, which can cause erosion of the articular cartilage on the head of the mandibular condyle. There has been little attention focused on treating the damaged condylar cartilage. Therefore, the overall goal of this research is to create a tissue engineering therapy for resurfacing the damaged cartilage of the condylar process with healthy living tissue. Initially, bovine condylar cartilage explants were studied to understand the tissue structure, composition, and gene expression of the native tissue. The cell response of isolated condylar chondrocytes encapsulated in photopolymerized poly(ethylene glycol) hydrogels as a tissue engineering scaffold was examined in the presence and absence of dynamic loading for up to three days of culture. Condylar chondrocyte viability was maintained within the PEG hydrogel constructs over the culture period and loading conditions. Cell response was examined through real-time RTPCR for collagen types I and II and aggrecan, nitric oxide production, cell proliferation, proteoglycan (PG) synthesis, and spatial distribution of extracellular matrix through histology. This study demonstrates that PEG hydrogel constructs are suitable for condylar chondrocyte encapsulation in the absence of loading. However, dynamic compressive strains resulted in inhibition of gene expression, cell proliferation, and PG synthesis.