Effects of Mesenchymal Stem Cells Treatment on Radiation-Induced Proctitis in Rats

PURPOSE: There are no effective treatment methods with which to control complications of radiation proctitis with fistula or recurrent bleeding following radiation treatment for prostate, cervical, or rectal cancer. Mesenchymal stem cells (MSCs) can induce immune modification, resulting in tissue repair and regeneration. Therefore, we used a rat model of radiation-induced proctitis and observed the effects of using human placenta-derived (PD) and adipose tissue-derived (AD) MSCs. MATERIALS AND METHODS: Female Sprague Dawley rats were irradiated at the pelvic area with 25 Gy. We injected 1×10(6) cells of human PD-MSCs, human AD-MSCs, human foreskin fibroblasts, and control media into the rectal submucosa following irradiation. We sacrificed rats for pathologic evaluation. RESULTS: Fibrosis on the rectum was reduced in both MSC groups, compared to the control group. Mucosal Ki-67 indices of both MSC injected groups were higher than those in the control group. Although caspase-3 positive cells in the mucosa gradually increased and decreased in the control group, those in both MSC injected groups increased rapidly and decreased thereafter. CONCLUSION: We demonstrated the effects of regional MSC injection treatment for radiation-induced proctitis in rats. MSC injection reduced fibrosis and increased proliferation in rat mucosa. Human AD-MSCs and PD-MSCs had similar effectiveness.