Stem Cell Therapies for the Resolution of Radiation Injury to the Brain.

Purpose of review: To encapsulate past and current research efforts focused on stem cell transplantation strategies to resolve radiation-induced cognitive dysfunction.

Recent findings: Transplantation of human stem cells in the irradiated brain was first shown to resolve radiation-induced cognitive dysfunction in a landmark paper by Acharya et al., appearing in PNAS in 2009. Since that time, work from the same laboratory as well as other groups have reported on the beneficial (as well as detrimental) effects of stem cell grafting after cranial radiation exposure. Improved learning and memory found many months after engraftment has since been associated with a preservation of host neuronal morphology, a suppression of neuroinflammation, improved myelination and increased cerebral blood flow. Interestingly, many (if not all) of these beneficial effects can be demonstrated by substituting stem cells with microvesicles derived from human stem cells during transplantation, thereby eliminating many of the more long-standing concerns related to immunorejection and teratoma formation.

Summary: Stem cell and microvesicle transplantation into the irradiated brain of rodents has uncovered some unexpected benefits that hold promise for ameliorating many of adverse neurocognitive complications associated with major cancer treatments. Properly developed, such approaches may provide much needed clinical recourse to millions of cancer survivors suffering from the unintended side effects of their cancer therapies.