A Study on the Preparation of Acellular Lyophilized Porcine Dermal Matrix and Xenograft

Biological skin substitutes can be used in human skin defects. However, with the exception of autograft, they are not permanent due to incompatible tissue antigenicity. In our study, we planned to determine the fate of porcine skin, preliminarily processed, in order to eliminate tissue antigenicity after implantation onto nude athymic mice. Harvested porcine skin was meshed and put through epidermal separation, decellular, lyophilization and antiseptic processes. After rehydration, the processed skin is grafted to the skin defect made on the back of a nude mouse. Then thin autologous skin is overlaid and secured with suture(Experimental group). The control group is recovered by autologous skin graft only. Evaluation for wound contraction area(1st, 2nd, 4th, 8th week) and histological analysis(2nd, 4th, 8th week)were performed.The porcine dermis became completely incorporated into the wound without evidence of rejection. The reduction in wound contraction in the experimental group was significant in comparison with that of the control group. In conclusions, the decellularization and lyophilization process was found to have destroyed cells regulating immune re sponse while preserving the structural organization of extracellular matrices. We are trying to focus on establishment and management of the skin bank for the preparation, storage of the porcine xenograft in the future.

A Study on the Preparation of Acellular Lyophilized Porcine Dermal Matrix and Xenograft

Biological skin substitutes can be used in human skin defects. However, with the exception of autograft, they are not permanent due to incompatible tissue antigenicity. In our study, we planned to determine the fate of porcine skin, preliminarily processed, in order to eliminate tissue antigenicity after implantation onto nude athymic mice. Harvested porcine skin was meshed and put through epidermal separation, decellular, lyophilization and antiseptic processes. After rehydration, the processed skin is grafted to the skin defect made on the back of a nude mouse. Then thin autologous skin is overlaid and secured with suture(Experimental group). The control group is recovered by autologous skin graft only. Evaluation for wound contraction area(1st, 2nd, 4th, 8th week) and histological analysis(2nd, 4th, 8th week)were performed.The porcine dermis became completely incorporated into the wound without evidence of rejection. The reduction in wound contraction in the experimental group was significant in comparison with that of the control group. In conclusions, the decellularization and lyophilization process was found to have destroyed cells regulating immune re sponse while preserving the structural organization of extracellular matrices. We are trying to focus on establishment and management of the skin bank for the preparation, storage of the porcine xenograft in the future.

Microvasclar Free Tissue Transfer for Aesthetic Facial Contouring

The facial contour deformity can cause significant handicaps in social life and a psychological stress to the patient. From January 1991 to November 1998, ten patients were operated on for correction of facial contour deformities with three types of free flap: deepithelialized scapular (n = 6), deepithelialized groin (n = 3) and omental free flap (n = 1). The distribution of diseases were Romberg's disease (n = 3), hemifacial microsomia (n = 2), facial lipodystrophy (n = 1), sequelae after surgery (n = 3) and post-traumatic deformity (n = 1). The patient ages ranged from 12 to 42 years. An incision was made at preauricular (n = 3) or submandibular area (n = 7). After making a subcutaneous pocket just above SMAS, the flap was placed within the pocket. The microvascular anastomosis was performed using superficial temporal vessel (n = 3) or facial vessel (n = 6) as a recipient. The flap margin was sutured to the fascia or periosteum and fixed by bolster sutures to reduce gravitational migration. There were no flap loss. Flap revisions consisting of minor contour corrections were performed in eight patients. A stable restoration of facial contour was achieved in all patients. Microvascular free tissue transfer has the advantages that it can be used on the irradiated bed and restore a large defect of facial contour. The deepithelialized groin free flap is suitable for correction of generalized defect of facial contour such as hemifacial microsomia because of its abundance of fatty tissue. In the deepithelialized scapular free flap, the dorsal thoracic fascia can be folded and tailored into variable width and thickness to correct subtle deformity of facial contour such as Romberg's disease or facial lipodystrophy. The omental free flap is not considered the first choice in facial contouring surgery as it requires laparotomy and has a greater tendency to gravitational migration.

Thin-shaving Technique to Harvest Calvarial Bone Graft with Periosteum for Treatment of Orbital Blow-out Fractures

Bone grafting is a preferred method for treatment of orbital blow-out fracture. However, in conventional bone graft technique, a harvested bony segment is often too thick to be directly grafted into the orbit so it requires trimming procedures, and its curvature is not easily matched to orbital fractured site. From January 1997 to July 1998, 17 patients with blow-out fracture were treated by using thin shaving techniques for harvest of calvarial bone with periosteum. The harvested bony segments were grafted as onlay method Eight patients complained diplopia postoperatively, but all resolved in a few months. We found no shifting of bone graft in postoperative CT scans and there were no hematoma, seroma, or intracranial hematoma. The advantages of our method are as follows. First, donor site defect was much smaller than in conventional method Second, the curvature of bone graft is easily molded and matched to cover the orbital fractured site. Third, the harvest of bone grafts easy and can be done rapidly. Fourth, the periosteum is attached We conclude that this method may be used as an alternative technique for harvesting bone graft for treatment of blow-out fractures.