The in vitro response of fibroblasts to the fluid that accumulates under a vapor-permeable membrane.

We decided to examine whether the mechanism for production of granulation tissue during moist wound healing under a vapor-permeable membrane (VPM) is related to a fibroblast growth-promoting substance in the wound fluid beneath the VPM. The experimental design utilized growth curves performed on synchronized fibroblast cultures derived from 2 normal infants. Cell counts were performed at days 1, 4, 7, and 11 (saturation density). VPM fluid (MWF, moist wound-healing fluid) from 7 different patients was used to supplement growth medium (GM) in the test growth curves. Both 2% MWF alone and 2% MWF plus 2% human serum (2 + 2) were evaluated for each patient. Control curves were conducted using GM supplemented with 2%, 4%, and 10% human serum (HS). When 2% MWF alone was added to culture medium, all cells lifted off the surface of the flask within 4-7 days. If (2 + 2) was used to supplement the medium, detachment did not occur. At days 4, 7, and 11, (2 + 2) flasks had significantly greater cell densities than did flasks supplemented with either 2% or 4% HS alone (p less than 0.001). At days 4 and 7, (2 + 2) cell counts were the same as 10% HS cell counts (p = 0.99). By day 11, (2 + 2) cell counts exceeded those of 10% HS (p less than 0.01). We conclude that the fluid that collects under the specific VPM used in this study when added to HS causes synergistic stimulation of fibroblast cell division and an altered pattern of fibroblast growth.