Reduced presence of tissue-repairing cells in wounds combined with whole-body irradiation injury is associated with both suppression of proliferation and increased apoptosis

The goal of our study was to examine the effects of whole body irradiation injury on tissue-repairing cells, so as to elucidate the possible mechanisms of reduced repopulation of tissue-repairing cells. The quantity of tissue-repairing cells in wounds from simple incision injury (WBI) (group S) and combined with WBI injury (group C) was measured histologically. The proliferation and apoptosis of tissue-repairing cells in wounds were determined using immunohistochemical staining for proliferation cell nuclear antigen (PCAN) and by TUNEL assay. Fibroblasts were isolated from the wounds, and their proliferation and apoptosis were detected in vitro. Some key molecules involving in proliferation (cyclin E and cyclin dependent kinase 4) and apoptosis (bcl-2 and bax) were also determined, so as to interpret the mechanisms of the alteration of tissue repairing cells. The quantity of tissue-repairing cells in group C was significantly less than in group S. The PCNA contents in wounds of group C were significantly less than in group S, whereas the apoptosis of tissue-repairing cells in wounds of group C increased significantly as compared to group S. The expression of the molecules involved in the mediating of proliferation and apoptosis coincided with the proliferation and apoptosis of tissue repairing cells in wounds. The quantity of tissue repairing cells in wounds combined with WBI injury is significantly less than in simple incision injury. This is associated with both suppression of proliferation and increased apoptosis.