ON THE MECHANISM OF SKIN WOUND CONTRACTION - A GRANULATION-TISSUE KNOCKOUT WITH A NORMAL PHENOTYPE

This report explores the mechanism of spontaneous closure of full-thic kness skin wounds. The domestic pig, often used as a human analogue fo r skin wound repair studies, closes these wounds with kinetics similar to those in the guinea pig (mobile skin), even though the porcine der mis on the back is thick and nearly immobile. In the domestic pig, as in the guinea pig, daily full-thickness excisions of the central granu lation tissue up to but not including the wound edges in both back and flank wounds do not alter the rate or completeness of wound closure o r the final pattern of the scar. A purse-string mechanism of closure w as precluded by showing that surgical interruption of wound edge conti nuity does not alter closure kinetics or wound shape. We conclude that ''tightness'' of skin is not a key factor nor is the central granulat ion tissue required for normal wound closure. These data imply that in vitro models such as contraction of isolated granulation tissue or of the cell-populated collagen lattice may not be relevant for understan ding the cell biology of in viv wound closure. Implications for the me chanism for mound closure are discussed.