Adoptive transfer of mesenchymal stromal cells accelerates intestinal epithelium recovery of irradiated mice in an interleukin-6-dependent manner.

Background Aims: Apoptosis of radiosensitive cells in the bone marrow and gut is a serious, at times life-threatening, complication arising from radiation exposure.

Methods: We investigated whether adoptive transfer of allogeneic bone marrow-derived mesenchymal stromal cells (MSC) could exert cytoprotective and life-sparing effects in a mouse model of sublethal total body irradiation (TBI).

Results: We demonstrated that a single intraperitoneal injection of C57Bl/6 MSC given to major histocompatibility complex (MHC)-mismatched Balb/c mice within 24 h of sublethal TBI significantly reduced mortality in a dose-dependent manner. Histologic analysis and Ki67 immunostaining of jejunum sections collected 3 and 6 days post-TBI indicated that MSC protected the gastrointestinal epithelium from TBI-induced damage and significantly accelerated recovery of the gut by stimulating proliferation of the crypt cell pool. Using interleukin-6(-/-) (IL-6) MSC, we demonstrated that IL-6 expressed by MSC played a role in gastrointestinal epithelium regeneration.

Conclusions: Our results suggest that allogeneic MHC-mismatched MSC may be exploited to reduce gastrointestinal complications and mortality arising from ionizing radiation exposure.