HUMAN WOUND-HEALING FIBROBLASTS HAVE GREATER CONTRACTILE PROPERTIES THAN DERMAL FIBROBLASTS

Contractile and phenotypic properties of human fibroblasts from healin g wounds were compared to those of dermal fibroblasts using in vitro m odels. Wound fibroblasts were recovered from implants, made of a polyv inyl alcohol sponge threaded into a perforated silicone tube, 12 days after their subcutaneous implantation in human volunteers. Dermal fibr oblasts were isolated from the skin of healthy subjects. Two morpholog ically different fibroblast populations were observed in cells culture d from implants. In order to characterize these fibroblast populations , intracellular alpha-actin expression was studied by immunofluorescen ce labeling of cells cultured in monolayer. This protein was detected in less than 1% of the dermal fibroblasts. By contrast, 30 to 40% of w ound fibroblasts were labeled and contained fiber networks of alpha-ac tin. These results confirm the presence of myofibroblasts in human wou nd healing tissues. The contractile property of fibroblasts and myofib roblasts was evaluated using a three-dimensional cell culture model (f ibroblast populated collagen gels). Cells were incorporated in a colla gen matrix and cultured for 14 days. The surface area of collagen gels was measured every day. Our results show that wound fibroblasts stron gly contract collagen gels during the first 24 hr (surface area at 24 hr = 20-55% of initial surface area) in comparison to dermal fibroblas ts (surface area at 24 hr = 70-75% of initial surface area). This supe rior level of contraction was observed until the fifth day of culture. In conclusion, these results show that in human granulation tissue, t he myofibroblast phenotype is abundant at Day 12 postwounding and that granulating wound fibroblasts have greater contractile capacity than dermal fibroblasts, in vitro. These gathered observations suggest that myofibroblasts are responsible for wound contraction in vivo. (C) 199 4 Academic Press, Inc.