GROWTH-FACTORS AND CANINE FLEXOR TENDON HEALING - INITIAL STUDIES IN UNINJURED AND REPAIR MODELS

The role of growth factors in a variety of bone and soft tissue healin g processes has been studied extensively in numerous recent models, ye t little is known about the specific growth factors that may be playin g a role in flexor tendon healing. We used a number of established pro tein purification techniques and bioassays to isolate and partially ch aracterize a heparin-binding growth factor from unoperated canine tend ons. Our data provide evidence that basic fibroblast growth factor, a potent angiogenic growth factor, is present in normal canine intrasyno vial flexor tendons. We then studied repaired canine flexor tendons to further elucidate the role of growth factors in the tendon healing pr ocess. Heparin-sepharose elution profiles from three repair intervals (3, 10, and 17 days) were graphed and compared to known profiles of is olated growth factors. The three repair intervals demonstrated two elu tion profile peaks, consistent with varying amounts of platelet-derive d growth factor and epidermal growth factor. Although additional exper imentation is required to identify definitively the various protein is olates, these data provide compelling evidence that a variety of growt h factors are present in uninjured and healing digital flexor tendons.