Stimulation of protracted connective tissue repair in normal mice by transforming growth factor beta 1

The repair and contraction during connective tissue repair of mesenteric perforations is prolonged in mice compared with rats. In the present study the stimulating effect of transforming growth factor beta 1 (TGF-beta 1) on different aspects of such repair of the mouse mesentery was assessed. The number of closed mesenteric perforations were counted on different days after operation and the free peritoneal cells were counted, the mitotic index was assessed, and actin distribution of fibroblasts around the perforation was studied with laser scanning confocal microscopy. TGF-beta 1 significantly increased the speed of closure and seemed to induce more actin in fibroblasts at the wound margin. It did not significantly influence the mitotic index, but fewer free peritoneal cells were obtained in mice treated with TGF-beta 1. We conclude that TGF-beta 1 is a potent stimulator of connective tissue repair and contraction in mice. The different methods of closure in rats and mice implicate different molecular responses in wounds and further studies on the stimulating effect of TGF-beta 1 may indicate basic fibroblastic cellular mechanisms that are active during contraction in connective tissue repair.