Glycosaminoglycan composition of uninjured skin and of scar, tissue in fetal, newborn and adult sheep

Few details are available on the heterogeneity of glycosaminoglycans (GAGs) in healing fetal wound tissue. We used a sensitive assay for hexosamines to examine changes occurring in the development of normal sheep skin and of wound healing tissue in PVA sponges inserted subcutaneously at different stages of gestation. It was assumed that glucosamine was derived mainly from hyaluronan and galactosamine mainly from dermatan sulphate and chondroitin sulphate. Hexosamine-containing tissue infiltrating the sponges was deposited more repidly in the first week than in the second week. Three days after wounding, approximately 70% of the total GAGs in wound tissue was hyaluronan. The proportion of hyaluronan then fell progressively and by the 14th day contributed 57% to total GAGs. In uninjured skin the contribution of hyaluronan to the total GAGs fell progressively with increasing fetal maturity, the level being 70% at 75 days gestation, but only 35-40% in newborn or adult skin. At no stage of development was there a sudden change in GAG composition suggestive of a transition from regeneration to scar formation. It is concluded that hyaluronan may play an important role in the biochemical sequence leading to collagen fibrillogenesis and mature scar formation.