Novel insights into the mechanism of decreased expression of type X collagen in human mesenchymal stem cells from patients with osteoarthritis cultured on nitrogen-rich plasma polymers: implication of cyclooxygenase-1.

ABSTRACT

Recent evidence indicates that a major drawback of current cartilage- and intervertebral disc (IVD) tissue engineering is that human mesenchymal stem cells (MSCs) from patients with osteoarthritis rapidly express type X collagen (COL10A1), a marker of late stage chondrocyte hypertrophy associated with endochondral ossification. We recently demonstrated that COL10A1 expression was inhibited in MSCs from patients with osteoarthritis cultured on nitrogen-rich plasma polymerized (PPEN) coatings. Here, we sought to understand the mechanisms of action of this effect by culturing MSCs on PPEN surfaces in the presence of different inhibitors of kinases and cyclooxygenases. The effect of PPEN surfaces on COL10A1 expression was found to be mimicked by the cyclooxygenase inhibitor NPPB, but not by daphnetin (an inhibitor of protein kinases) nor by genistein (an inhibitor of tyrosine kinases). COL10A1 expression was also suppressed by the specific cyclooxygenase-1 (COX-1 SC-560) and 5-lipoxygenase (5-LOX MK-866) inhibitors, but not by COX-2 (COX-2 inhibitor 2) and 12-LOX (baicalein) inhibitors. Finally, the incubation of MSCs on PPEN surfaces inhibited the expression of COX-1 while 5-LOX was not expressed in these cells. Taken together, these results indicate that PPEN surfaces inhibit COL10A1 expression via the suppression of COX-1.