Mesenchymal stem cells - A new hope for radiotherapy-induced tissue damage?

Mesenchymal stem cells (MSCs) have been isolated from various organ sites including bone marrow, skin, vascular and adipose tissues and form a heterogeneous population of multipotent stromal cells. They have been shown to exhibit a relative radiation resistance and retain their stem cell properties even after high doses of ionizing radiation. The regenerative potential of MSCs has been widely studied in the context of ischemic or mechanical forms of tissue damage, and these stem cells may also constitute a powerful means of treating tissue lesions caused by ionizing radiation, either after accidental exposure to radioactivity or as a side effect of clinical radiotherapy. Animal studies and early clinical experiences suggest a role for MSCs in the regeneration of these tissue lesions both by differentiating into functional parenchymal cells and by creating a nurturing microenvironment for other cells. Here, we review the published data on the regenerative properties of MSCs in the context of organ-specific radiation damage. Potential mechanisms and clinical applications are outlined, and problems and challenges of MSC-based treatments for radiation injuries in the clinic are summarized.