Pathohistology Characteristics On Wound Healing Of Full-thickness Skin Burn And Its Clinical Significance

ObjectiveTo deeply investigate the basic regularity and characteristic in the processes of III degree burn wound healing, especially vascularization and granulation tissue formation in the junction between necrotic skin and viable hypodermis after full-thickness skin burn, and their relationships with the occasion for skin grafting and the treatment of transplant bed on the selected III series mini-pig from different levels:. system, histology, cell and protein molecule.MethodsFull-thickness skin burn model was made on the selected adult minipigs and the changes of pathohistology, emerging vascular endothelial cells and micro-vessels, the expression of basic fibroblast growth factor(bFGF), neoformative collagen fibers, and fibroblastic ultrastructure in full-thickness skin burn wound and the junction area were observed dynamically at different phases by the techniques of gross observation, HE staining, immunohistochemical staining (vascular endothelial cell, bFGF), VG staining (collagen fiber) and transmission electron microscope examination (fibroblast). Twenty-four cases of III degree burn was chosen for necrotic tissue excision and autoskin grafting on the fault hypodermis, and the changes after wound healing were observed. The observation contained the survival of the grafted skin, the shrinkage of the wond. impair of looking, and changes of pliability and flexibility.ResultsVascular endothelial cells and fibroblasts started to proliferate from resident cells in the junction area in24-48h postburn. At the7th day, the wound became drying and shrinking, while granulation tissue formed preliminarily, blood supply improved, neoformative collagen fiber emerged and fibroblast was in a state of vigorous protein-synthesis and active function. In10-14d postburn, widespread vascularization happened in the junction area with more blood supply, and granulation tissue present fibrosis and expansion. After21d, eschar separated and granulation tissue revealed and developed into maturating and aging connective tissue with myofibroblast (MFB) visible. The wound shrunk approximately by14%and evident edema happened in superficial granulation tissue at30th day. Proliferation of vascular endothelial cells and expression of bFGF occurred through the whole process of vascularization and granulation tissue formation. And their crest-times arrived in72h-7d and5-7d. The grafting skin of the selected case survived all but two which happened point-like necrosis. The follow-up of the healing wound1year later showed plump appearance, light wound-contraction, wide range of motion and good softness.ConclusionAlthough necrotic skin existed all or partly in the wound after7-10d postburn, vascularization happened in the junction and granulation tissue expanded following its regularity. According to situation of the body and the local, operation of necrotic tissue and granulation tissue excision and autoskin grafting on the fault hypodermis should be implemented as soon as possible, and transplant bed lied on the superficial hypodermis with improved blood supply. And this kind of operation brought exact outcome of high survival rate of grafting and good quality of healing.