Myofibroblasts and colonic anastomosis healing in Wistar rats

BACKGROUND: The myofibroblasts play a central role in wound healing throughout the body. The process of wound healing in the colon was evaluated with emphasis on the role of myofibroblasts. METHODS: One hundred male Wistar rats weighing 274 ± 9.1 g (mean age: 3.5 months) were used. A left colonic segment was transected and the colon was re-anastomosed. Animals were randomly divided into two groups. The first group experimental animals (n = 50) were sacrificed on postoperative day 3, while the second group rats (n = 50) were sacrificed on postoperative day 7. Healing of colonic anastomosis was studied in terms of anastomotic bursting pressure, as well as myofibroblastic reaction and expression of α-smooth muscle actin (α-SMA), adhesion formation, inflammatory reaction and neovascularization. RESULTS: The mean anastomotic bursting pressure increased from 20.6 ± 3.5 mmHg on the 3(rd )postoperative day to 148.8 ± 9.6 Hg on the 7(th )postoperative day. Adhesion formation was increased on the 7(th )day, as compared to the 3(rd )day. In addition, the myofibroblastic reaction was more profound on the 7(th )postoperative day in comparison with the 3(rd )postoperative day. The staining intensity for α-SMA was progressive from the 3rd to the 7th postoperative day. On the 7(th )day the α-SMA staining in the myofibroblats reached the level of muscular layer cells. CONCLUSIONS: Our study emphasizes the pivotal role of myofibroblasts in the process of colonic anastomosis healing. The findings provide an explanation for the reduction in the incidence of wound dehiscence after the 7th postoperative day.