| Although there are some published documents about HHK artificial tendon (AFT) implantation, a systemic research on its induction of autogeneous tendon (AUT) formation is absent. In this experi- ment, the rabbit achilles tendon was trans-sected by 2~3cm and an artificial tendon was implanted instead . We observed the mor- phological changes of implanted AFT, the changes of collagen levels as well as the expression of some growth factors in tissue around the implanted tendon. The key techniques used in the study included 5histological technique, in situ hybridization, and amino acid assay, etc. By light microscopic and electronic microscopic technique, we proved that nine weeks after implantation, the AFT had been com- pletely replaced by an AUT. One week postoperatively, a fibrous sheath appears. Slowly, it turned thicker and thicker, and wrapped the implant up. The fibrous sheath supplied the activities of the degradation of AFT and the formation of AUT with a relatively ideally closed environment. The epitendon derived from the fibrous sheath eventually might start up and lead to the whole process of AUT formation. During the formation of AUT, AFT might experience a programmed process. First, it was surrounded by inflammatory cells, which might soon be partially replaced by newly formed granulation tissues, then, with the infiltration of macrophages, AFT began to be splitted, digested, and absorbed, and disappeared eventually. Nine weeks after implantation, the implant could not be distinguished from natural tendon by naked eye. Moreover, both of their morphological manifestations were very similar. We supposed that during the course, fibroblasts might secrete collagen and produce collagen fibers, growth factors such as bFGF and TGFs be involved in the induction of AUT, and finally, 4 tenocytes play key roles in the formation and remodeling of the AUT through the production of different type of collagen. Van Geison (VG) staining was put into use for showing collagen fiber, and spectrophotometrjc method was recommended to detect hydroxyproline (HyP) levels in collagen. The result showed that the HyP contents increased gradually during two to six weeks after operation, but decreased during the ninth week. Statistics analysis showed that HyP contents in AUT in various phases except that in the ninth week were obviously different from a natural tendon. The result of VG staining made clear that collagen must go through a course from immature to mature, and from irregular to regular . All the results confirmed the fact that the AFT did induce the formation of AUT. With in situ hybridization technique, we got some important information about the expression and location of two key growth factors, bFGF and TGF P 2. Two weeks postoperatively, bFGF showed strongly positive reaction in cells of the fibrous sheath in the immature connective tissue. Three weeks later, we found fibrOblasts in the sheath expressing TGF P 2 greatly. In other phases, only weak or negative expression was observed. The above-mentioned results suggested that the induction of the formation of AUT by the implantation of HI-IK artificial tendon be a highly programmed course, including the infiltration of inflammatory cells to the surrounding tiss... |
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