Use of a rotating bioreactor toward tissue engineering the temporomandibular joint disc

This objective of this study was to determine the effects of a rotating bioreactor in temporomandibular joint (TMJ) disc tissue engineering. Porcine TMJ disc cells were seeded at a density of 20 million cells/mL onto nonwoven poly(glycolic acid) (PGA) scaffolds in spinner flasks for 1 week and then cultured either under static conditions or in a rotating bioreactor for a period of 6 weeks. A series of analyses was performed, including mechanical testing, measurement of cellularity, quantification of matrix biosynthesis with a hydroxyproline assay and enzyme-linked immunosorbent assays, and observation of matrix distribution with immunohistochemistry. Between the bioreactor and static cultures, there were marked differences in gross appearance, histological structure, and distribution of collagen types I and II. Engineered constructs from the bioreactor contracted earlier and to a greater extent, resulting in a denser matrix and cell composition. In addition, immunostaining intensity was generally uniform in static constructs, in contrast to higher intensity around the periphery of bioreactor constructs. Moreover, bioreactor constructs had higher amounts of collagen II than did static constructs. However, differences in total matrix content and compressive stiffness were generally not significant. On the basis of the results of this study there is no clear benefit from use of the rotating bioreactor, although a sequence of static culture followed by rotating bioreactor culture may prove in the future to be more beneficial than either alone.