TENDON REPAIR - CELLULAR ACTIVITIES IN RABBIT DEEP FLEXOR TENDONS ANDSURROUNDING SYNOVIAL SHEATHS AND THE EFFECTS OF HYALURONAN - AN EXPERIMENTAL-STUDY IN-VIVO AND IN-VITRO

One deep flexor tendon and its surrounding sheath of each hindpaw of 4 8 rabbits were transected and repaired in order to investigate the abi lities of rabbit flexor tendons and synovial sheaths to synthesize DNA and matrix components during healing and to study the effects of hyal uronan (HA), After repair, HA or saline was injected between the tendo n and the sheath. Short-term culture and labeling in vitro were used u p to 6 weeks after surgery to determine synthesis of DNA, proteoglycan , collagen, and noncollagen protein. Within tendon repair sites, the r ate of cell proliferation increased and reached a maximum 5 days after surgery; within repaired synovial sheaths, the rate immediately decre ased. In the healing tendons, the rare of collagen synthesis decreased and the rate of noncollagen protein synthesis remained unchanged. The opposite results were found within the healing synovial sheaths. HA d id not affect the rate oi cell proliferation or matrix synthesis in he aling tendons or surrounding sheaths. These results show that cellular activities differ between tendons and synovial sheaths during healing and that those activities may not be affected by HA.