Objective: Implantation of synthetic temporomandibular joint (TMJ) disc replacements aimed to alleviate pain and restore functional losses caused by TMJ disorders. Unfortunately, these synthetic replacements have been largely unsuccessful and in some instances have incited severe immune responses. Tissue engineering, however, may provide viable TMJ disc replacements. Towards this end, we have studied TMJ disc gene expression as a measure of protein production potential. With passage, collagen type I and aggrecan gene expression decrease in TMJ disc cell cultures. We hypothesize that surfaces coated with TMJ disc proteins may rapidly recover the lost gene expression in passaged TMJ disc cells.
Design: To study these effects, passages 0, 1, and 2 TMJ disc cells were plated in wells coated with aggrecan, collagen type I, collagen type II, or decorin. Safranin O staining was conducted to visualize cell aggregation.
Results: At passage 0, cultures appeared similar on each surface; however, by passages 1 and 2, aggrecan-coated and decorin-coated surfaces appeared to have more cell aggregates. Gene expression data did not correspond to these visual changes. No treated surface offered a significant change in aggrecan, collagen type I, or decorin expression relative to untreated controls. Furthermore, aggrecan and collagen type I gene expression dropped relative to samples taken prior to plating.
Conclusions: These results indicate that, despite visual changes described by cell aggregates, protein coatings have limited effects for recovering TMJ disc gene expression in monolayer cultures.