The effects of reduced oxygen tension on cell proliferation and matrix synthesis in synovium and tendon explants from the rabbit carpal tunnel: an experimental study in vitro.

Local ischemia may play an important role in the development of tendon degeneration as well as entrapment neuropathies. In order to investigate the cellular effects of hypoxia on tendon and synovial tissue from the carpal canal, dose response effects of oxygen on cell proliferation and synthesis of matrix components were examined in segments of synovial and flexor digitorum profundus tendon from the carpal tunnel of rabbits during short term culture. Explants were incubated in airtight containers flushed with either 0%, 1%, 3%, 20% O2 plus 2% CO2 and N2 to balance and labeled with either 3H-thymidine or 3H-proline and 35S-sulfate. Cell proliferation was significantly inhibited by hypoxia in synovium but not in tendon (P = 0.03). In parallel, the synthesis of non-collagenous proteins was significantly reduced in synovium but not in tendon (P = 0.006). In both tissues hypoxia significantly inhibited collagen synthesis. On the other hand, hypoxia had no significant effect on the synthesis of new proteoglycans as determined by 35S-sulfate incorporation. Hypoxia can inhibit cell proliferation and alter synthesis of matrix components in synovial tissue, but may only have minor effects on non-collagen protein synthesis in tendon explants from the carpal canal of rabbit forepaws.