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 re-current 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 1x106 cells of hu-man PD-MSCs, human AD-MSCs, human foreskin fibroblasts, and control media into the rectal submucosa following irradia-tion. 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 in-creased 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 injec-tion reduced fibrosis and increased proliferation in rat mucosa. Human AD-MSCs and PD-MSCs had similar effectiveness.