Mast cells enhance migration and proliferation of fibroblasts into an in vitro wound.

The effects of mast cells (MC) in an in vitro wound model were studied. The model consisted of rat peritoneal MC cultured on confluent monolayers of 3T3 fibroblasts (MC/3T3). A linear wound was performed by cutting along the midline and scraping one half of the monolayer. After 42 h fibroblasts were counted in the scraped area of the wound. In the MC/3T3 cocultures 27.6 +/- 2.1 fibroblasts were found compared to 16.6 +/- 0.9 in the 3T3 cultures. The most significant increase in the number of fibroblasts was obtained upon activation of the MC with anti-IgE antibodies immediately after wound production (39.9 +/- 2.1). Stimulation with compound 48/80 had a weaker effect (32.7 +/- 1.5). Incubation of 3T3 wounded monolayers with supernatants of anti-IgE- or compound 48/80-activated MC, or with sonicated MC, induced an increase in fibroblast number similar to that found in unactivated MC/3T3. [3H]Thymidine incorporation followed by autoradiography was performed to assess fibroblast mitosis. The highest number of labeled fibroblasts beyond the wound line was found in immunologically activated MC/3T3 (29.7 +/- 4.4), followed by compound 48/80-activated MC/3T3 (18.4 +/- 1.5), MC/3T3 (15.1 +/- 3.6), and 3T3 (10.6 +/- 2.6). After addition of aphidicolin, which inhibited fibroblast mitosis, MC were still effective in enhancing fibroblast migration. In all the cocultures MC were observed to have migrated alongside fibroblasts. Thus merely the presence of MC adhering to wounded fibroblast monolayers significantly enhanced migration and proliferation of the fibroblasts. A further increase was achieved by immunological activation of the MC. We therefore suggest that MC have a facilitating role in this in vitro wound model.