Versican in human fetal skin development

The extracellular matrix of human fetal skin differs substantially from tha t of adult skin. Fetal skin contains sparse amounts of fibrillar collagen e nmeshed in a highly hydrated amorphous matrix composed of hyaluronan and su lfated proteoglycans. Both fetal and adult skin contain two major interstit ial proteoglycans that are extracted by chaotrophic agents and detergents. These are the large chondroitin sulfate proteoglycan versican and the small dermatan sulfate proteoglycan decorin. For this study, proteoglycans extra cted from fetal and adult skin were compared on Western blots to determine the relative amounts of versican. Decorin present in the same samples provi ded an internal standard for these studies. Fetal skin differed from adult skin in that it contained a significantly higher proportion of versican tha n did adult skin. Immunohistochemical studies compared early-fetal with mid -fetal skin and found that versican was a significant component of the inte rstitial extracellular matrix at both of these stages of skin development. However, by the mid-fetal period, interstitial versican became restricted t o the upper half of the dermis, although versican also continued to be high ly expressed around hair follicles, glands, and vasculature in the lower ha lf of the dermis. Fetal skin extracts differed from an adult skin extract b y the presence of a 66-kDa protein immunologically related to versican and by the absence of a 17-kDa core protein of a proteoglycan related to decori n. Both of these molecular species may represent degradation products of th eir respective proteoglycans. Monoclonal antibodies which detect epitopes i n native chondroitin sulfate glycosaminoglycan chains recognized versican e xtracted from fetal skin. However, the tissue distribution of these antigen s did not entirely conform to that for versican core protein, suggesting th at versican in different regions of the skin may be substituted with glycos aminoglycan chains with different microchemistries. The results of these st udies indicate that human fetal skin is structurally different from adult s kin in terms of both the distribution and the composition of the large, agg regating chondroitin sulfate proteoglycan versican.