The vascularization of artificial skin grafts in rats: its modification by protamine

Artificial skin is a recent development in the clinical care of the severely burned patient. Its manufacture involves the covalent bonding of collagen and polysaccharide, followed by the coating of one surface with a thin layer of silicone rubber. Neovascularization and its modification in artificial skin were studied. Experimental artificial skin was grafted onto rats and examined for vascular growth in the graft at 7 days. This was revealed by latex-perfused vascular casts which were processed for histological study. An area including the graft bed and graft matrix was viewed and examined for latex-filled vessels. Thirty-seven percent of the total vessels, identified by residual latex, had grown into the graft. When artificial skin was treated with protamine at 10 mg/ml buffered saline solution before grafting, only 6% of the total perfused blood vessels were found in the graft matrix. The remainder was found in the graft bed. Moreover, increases in the numbers of perfused blood vessels and vessel diameters were observed in the graft bed at the interface below the graft pretreated with protamine. Protamine inhibited vessel growth into the matrix, but promoted an increased number of dilated blood vessels in the surrounding graft bed. These dilated vessels were related to an altered vessel architecture.