The processing of sheepskin for use as a dermal collagen graft--an experimental study

In search of a biological mesh-prosthesis, sheepskin was processed according to established methods in the manufacture of leather. The dermal collagen fibre-mesh of sheepskin was purified by a proteolytic enzyme treatment after which the skins were split, providing a split-skin graft corresponding to the reticular layer of the dermis. The split-skin graft was subsequently tanned with a buffered glutaraldehyde solution (1.5% w/w, pH = 8, time of exposure 2 1/2 hrs, temp. 20 degrees C). Tannage was assessed by determination of the hydrothermal shrinkage temperature (Ts) of the grafts. Ts of the untanned grafts was 44.5 degrees C (n = 43, SD = 4.8). Glutaraldehyde tannage resulted in an elevation of Ts to 74.8 degrees C (n = 36, SD = 0.8). Untanned and tanned specimens were implanted subcutaneously in rats. Short-term (3-21 days) and long-term (6-36 weeks) survival periods were studied. The untanned graft evoked a minimal tissue-response consisting of host fibroblasts and blood-vessels which had reinhabited the graft. In contrast, the tanned graft elicited a moderate degree of foreign body reaction and a greater fibroblastic and vascular response. The untanned graft had been absorbed by the 36th week, whereas the tanned graft had persisted, concurrently invoking the deposition of newly formed, fibrous collagen. The intended practical application of the glutaraldehyde tanned dermal collagen graft in surgery includes its use as a mesh-prosthesis, a wound dressing, a tendon or ligament substitute and as a vascular conduit.