In vivo TGF-β3 expression during wound healing in irradiated tissue. An experimental study

Material and Methods: A total of 48 Wistar rats (male, weight 300-500 g) were used in the study. A free myocutaneous gracilis flap was transplanted in 30 rats: group 1 (n = 18 rats) no transplantation, only irradiation (3 x 10 Gy); group 2 (n = 14 rats) transplantation without preoperative irradiation; group 3 (n = 16 rats) transplantation following preoperative irradiation (3 x 10 Gy). The interval between radiotherapy and grafting was 4 weeks. Tissue samples were taken perioperatively and postoperatively after 3, 4, 7, 11, 14, 28, and 30 days from the transition area between the graft and the graft bed and from the graft bed itself. The TGF-β3 expression was analyzed immunohistochemically (labeling index) both qualitatively and quantitatively and checked for statistical differences between the groups (p < 0.05). Results: The success rate for graft healing was 75% in the group irradiated with 30 Gy, and 86% in the nonirradiated group. The rats that were irradiated but not operated on showed significantly (p = 0.04) reduced TGF-β3 expression in the graft bed immediately after the end of the irradiation. Whereas only minor differences in TGF-β3 expression were observed postoperatively in the graft bed and in the transition area between the graft and the graft bed in the group where a graft was carried out without preirradiation, the group that was preirradiated with subsequent grafting showed a significantly reduced expression in the bed (p = 0.018). Conclusion: After irradiation, it was possible to measure reduced TGF-β3 expression in the irradiated graft bed. The exogenous application of TGF-β3 could therefore present a new therapeutic approach for improving wound healing through radioprotection of nontransformed epithelial cells and fibroblasts after preoperative radiotherapy and surgery. (orig.)