The Experimental Study And The Preliminary Clinical Application Of Bacterial Collagenase In Catabolizing Abnormal Scars

Hypertrophic scar and keloid (abnormal scars) are common diseases in clinics of plastic surgery. These abnormal scars may produce bothersome itching, burning, stinging, or painful sensations, and are major causes of functional, cosmetic and psychological morbidity.Because of the 55% recurrence rate by surgical treatment, too long-term pressure that must be maintained day and night in compression therapy, and the severe side-defects of steroid injection and radiation, our ability to control abnormal scars is limited. There is no routine effective form of therapy by now. As the abnormal scars are marked by excessive collagen accumulation, which is far more than needed level. We began these studies both by experimental and clinical trails, in the hope of finding a collagenolysis method that can catabolize native collagen effectively. As a result, the bacterial collagenase reviewed a rapid and significant effect in reducing scar volumes.In an effort to develop an experimental model for studying collagenolysis, we established athymic mouse model of HS (hypertrophic scar). The athymic mouse implant model is the closest approximation to human hypertropic scars and keloids, the implanted scar tissues has been proved maintaining their histological appearances, cellularity and glycosaminoglycan distribution without immune response. Therefore, this model is available for testing a certain method in therapeutic experiment. In order to measure the volume of implanted hypertrophic scar tissues conveniently, we put bigger pieces of HS into subcutaneous pocket of the mice. The size of the tissue is three times larger than common used.By histological and TEM(transmission electron microscopy) examinations, the implants that were harvested at various time intervals from 10 to 210 days post implantation, having retained their original morphological characters by 21 days. In situ hybridization and immunohistochemical methods were used to determine the expression of collagen genes and the formation of vascularization. As a result, the messenger ribonucleic acids(mRNA) coding for type I collagen synthesis was demonstrated clearly in the fibroblast cells in the period of 21—60 days. And the confirmed vessels were also found exist in the midportion of the implants by 21 days post implantation. All these results suggest that the nude mouse model of HS is the workable one for therapeutic experiment.On the basis of establishing HS nude mouse model, we developed a therapeutic experiment to evaluate the collagenolysis ability of the bacterial collagenase. The injection of collagenase into HS tissue in nude mice resulted in 86% volume reduction after twice injections within two weeks,...