Of the estimated 1,665,540 new cancer cases diagnosed in the US in 2014, approximately two thirds of patients will be treated with radiation therapy. This means that over 1 million people each year receive the benefits as well as the side effects of this treatment. Radiation is effective in treating many types of cancers, but it also unfortunately attacks the precursors of the cells (oligodendrocytes) that make insulation (myelin) in healthy brain cells that is important for efficient brain cell communication. This loss of insulation causes radiation patients to experience cognitive decline and motor impairment which can persist for the rest of their lives. Dealing with these symptoms such as decreases in memory and loss of higher intellectual functions can be devastating, especially for children, but there is new evidence that these cognitive side effects can be treated with the help of stem cells.
In this study, the researchers directed human stem cells to develop into the precursor cells for the cells that make the insulation. These precursors were then injected directly into various areas of the brains of rats who had undergone a radiation regimen similar to what human cancer patients commonly experience. After 10 weeks of precursor injections, researchers tested for improvements in the rats’ learning, memory, and balance.
Irradiated rats that had been injected in their forebrain recognized that an object had been moved or that they were being presented with a new object better than untreated irradiated rats, showing that learning and memory was improved with the injections. Also, when injected in their cerebellum, rats were able to to perform better on motor tasks such as balancing and trotting on a rotating pole. Additionally, imaging showed that the injected cells were surviving and continuing to provide insulation, suggesting the injections were responsible for cognitive and motor improvements. This development could mean that soon over 1 million people a year will not have to make the impossible choice between effective cancer treatment and avoiding life-long cognitive disability.