Safer stem cell-derived therapy for brain radiation recovery

Safer stem cell-derived therapy for brain radiation recovery

While stem cells have shown promise for treating brain regions damaged by cancer radiation treatments, University of California, Irvine researchers have found that microscopic vesicles isolated from these cells provide similar benefits without some of the risks associated with stem cells.

In research with rats, these membrane structures secreted by cells – called microvesicles – transplanted two days after cranial irradiation restored cognitive function, reduced inflammation and protected neurons, as measured in four- and six-week assessments, with no sign of immunorejection or tumor growth – two stem cell-related risk factors. Study results appear in the journal Proceedings of the National Academies of Science.

Microvesicles are small, fluid-filled sacs secreted by all human cells. Their plasma contains a range of bioactive cargo (proteins, RNAs, etc.) that can benefit cellular physiology. In the brain, they help regulate the health and functionality of neurons. Microvesicles also can play an important role in tissue regeneration.

The team isolated and removed microvesicles secreted by multipotent human neural stem cells. Through a series of injections in areas above the hippocampus – a region known for the growth of new neurons – microvesicles were transplanted into the brains of rats that had undergone radiation treatment. Each injection contained 2 microliters of microvesicles.

Starting one month after irradiation, the rodents receiving microvesicle injections showed significant improvements in cognition as gauged by four independent behavioral tasks. These cognitive benefits were associated with considerable reductions in neuroinflammation and the preservation of neuronal structures – both classic signs that radiation injury in the brain was either prevented or reversed.

Further work is needed to identify the specific factors within microvesicles that are responsible for the neuroprotective effects and to determine how long these beneficial effects persist.