Objective: To establish a real animal model for hypertrophic scar.
Methods: 388 wounds on the ears of 47 rabbits were created including rounds 6 mm in diamiter on ventrol or dorsal side and 1.5 cm x 4.5 cm rectangular wounds. Histological and histochemical analyses, in situ hybridization and cell apoptosis were tested.
Results: 70 percent of the wounds can from excess dermal scarring which is similar to human hypertrophic scar. The hight of excess dermal scarring is as 3-4 times high as original ventol skin. The excess scarring can last 150 days at the most. while 80 percent appears on rectangular wounds and it lasts more than 262 days. Large amount of fibroblasts, nodular and spiral structures exist in excessive dermal scarring. Local injection of TGF-beta 1 and IFN-r can promote and inhibit the formation of excessive dermal scarring respectively. SDS-PAGE shows that type III collagen content increased in excessive dermal scarring. In situ hybridization shows long-lasting expression of type I and III precollagen mRNA in excessive dermal scarrint. TGF-beta 1 mRNA also cope with that of precollagen. Fibroblast apoptosis in excessive dermal scarring of this model indicate that fibroblast apoptosis plays an important role in the process of occurrance, development of abnormal scar.
Conclusion: After wounding, rabbit ears can produce excessive dermal scarring which is similar to human hypertrophic scar. This can be used as an experimental model for the study of cicatrix.