STIMULATION OF FIBROBLAST PROLIFERATION AND MATRIX CONTRACTION BY WOUND FLUID

Fibroblast proliferation and fibroblast-mediated matrix contraction ar e critical to wound healing. Different cytokines have been shown to mo dulate fibroblast functions but little is known about the physiologica l role of these soluble factors during wound repair. In these experime nts we characterized a fibroblast stimulating factor in wound fluid. W ound fluid was obtained from subcutaneously implanted polyvinyl alcoho l sponges harvested 10 days post-wounding (pool of 100 Lewis rats). No rmal dermal fibroblasts were obtained from Lewis rats by an explant te chnique, while wound fibroblasts were isolated from sponges harvested 10 days post-wounding. Proliferation in response to 0.5% and 10% fetal bovine serum was assessed by [H-3]-thymidine incorporation. A fibrobl ast-populated collagen lattice was used for assaying contractile prope rties. Wound fibroblasts demonstrated markedly diminished proliferativ e and enhanced contractile properties compared to normal dermal fibrob lasts. 10% wound fluid (v/v) stimulated proliferation of normal dermal fibroblasts (119%, p < 0.001) and wound fibroblasts (103%, p < 0.001) . Wound fluid also stimulated collagen gel contraction by normal derma l fibroblasts (24% at 24 hr and 16% at 72 hr, p < 0.01), but not by wo und fibroblasts. Separation by Sephadex G-100 gel filtration identifie d the active factor in wound fluid to have a molecular weight of about 100 kDa. Characterization of the soluble factor showed it to be a pro tein (ammonium sulfate precipitation), sensitive to trypsin digestion, heat resistant (56 degrees C, 30 min), and neuraminidase resistant. T he isoelectric point appeared to be 7.0, as determined by ion exchange chromatography. Mitogenic proliferation of thymic lymphocytes was not affected by the active factor, suggesting cell target specificity. Th ese data demonstrate that the wound environment contains high molecula r weight protein(s) that promote fibroblast functions, essential for t he healing process. (C) 1997 Elsevier Science Ltd. All rights reserved .