TYPE-VII COLLAGEN GENE-EXPRESSION IN HUMAN UMBILICAL TISSUE AND CELLS

BACKGROUND: Type VII collagen is a minor collagen found in anchoring f ibrils. It is expressed predominantly by keratinocytes. In this study, we report the localization and spatial distribution of type VII colla gen gene expression in the human umbilical cord, a fetal-derived tissu e. EXPERIMENTAL DESIGN: Human umbilical cords were examined in indirec t immunofluorescence studies, employing a mouse monoclonal anti-human type VII collagen antibody. Endothelial cells were cultured from the v ein and grown on chamber slides for the detection of type VII collagen epitopes. In addition, cultured human umbilical vein cells were analy zed by Northern transfer analysis and by polymerase chain reaction for the expression of the corresponding gene. Fibroblast-like cells were isolated from the Wharton's jelly and were analyzed similarly for type VII collagen expression as well. RESULTS: We demonstrate that type VI I collagen is expressed by human umbilical tissue and cells. Indirect immunofluorescence studies demonstrate the presence of type VII collag en epitopes in the epithelium surrounding a connective tissue region k nown as Wharton's jelly. In addition, there was low but detectable imm unofluorescence signal associated with endothelial cells of blood vess els within the umbilical cord. In vitro, the fibroblast-like cells cul tured from the Wharton's jelly showed prominent type VII collagen sign al. This result was supported by the finding of high level of type VII collagen mRNA in these cells. The human endothelial cells from the ve in demonstrated weak but detectable staining for type VII collagen, an d the corresponding gene expression was shown by polymerase chain reac tion analysis of the mRNA of the endothelial cells. CONCLUSIONS: The r esults show that umbilical tissue and cells, specifically those from t he Wharton's jelly, are relatively enriched in type VII collagen. Ther e is differential spatial localization of this collagen in the fetal t issue. The novel finding is that cells, other than epithelial cells su ch as keratinocytes, are able to express the type VII collagen gene.