Effects of UCMSCs Delivered through Different Transplantation Approaches on Acute Radiation Enteritis in Rats

Radiation enteritis is the most common and serious complication of abdominal or pelvic radiation therapy. Mesenchymal stem cells (MSCs), as well as cell protection agents, inhibit apoptosis and promote the proliferation of injured tissues. 3 human umbilical cords MSCs (UCMSCs) were injected into the tail vein or peritoneal cavity of a rat model of radiation enteritis. The temporary protective effect was assessed by identification of donor cells, detection of cellular immune parameters and inflammatory cytokine levels, quantitation of jejunum mucosal preservation and examination of the rat remaining life. Only the rats in the intraperitoneal injection group exhibited a few positive donor cells 7 days after transplantation. CD₄⁺/CD₈⁺ T cells, a cellular immune parameter, decreased in the abdominal exudate of intraperitoneal injection group, compared with the model-only control and tail vein groups (both P < .05). Both serum and abdominal exudate TNF-α and IL-6 levels in the intraperitoneally injected rats rapidly decreased and were significantly different from those in the model-only control and tail vein injection groups (all P < .05). Mucosal surface area and survival time increased in the intraperitoneal injection group compared with the vehicle and tail vein injection groups (all P = .000). Therefore, the administration of UCMSCs with intraperitoneal injection approach postponed death in a rat model of radiation enteritis, which was associated with reduced serum levels of proinflammatory cytokines (TNF-α, IL-6). However, UCMSCs injected via the tail vein triggered an intense cellular immune response in the serum that adversely affects their survival. This treatment failed to suppress circulating serum and abdominal exudate levels of TNF-α and IL-6 and could not provide a therapeutic benefit for prolonging life against acute radiation enteritis.