The fate of cutaneously and subcutaneously implanted trypsin purified dermal collagen in the pig.

Pig dermal collagen was prepared by treating whole skin with a solution of crystalline trypsin at temperatures below 20°. The purified dermal collagen was implanted subcutaneously and into full thickness excised skin wounds in the pig. Biopsy specimens were removed after various periods of time and examined histologically. A parallel series of control experiments involving auto- and homografted skin were carried out under the same conditions, together with observations on full thickness excised wounds. Autografts and homografts behaved as previously described, the autografts appearing normal after 35 days while homografts were uniformly rejected and sloughed by Day 20 and contractions occurred as in open wounds. The dermal collagen grafts were invaded and colonized by host fibroblasts and other cells and became at least in part revascularized and re-epithelialized. The implanted collagen was progressively lysed and replaced by granulation tissue. Remnants of collagen persisted in peripheral parts of the graft up to Day 35 but had disappeared by Day 50. Dermal collagen implants covered with split thickness auto- and homografts suffered the same fate as the dermal collagen grafts. Dermal collagen implanted subcutaneously into adipose tissue achieved in some instances a state of permanence, the collagen bundles retaining their original form and containing fibroblasts and capillaries.