Stem Cells Restore Lost Cognitive Powers in Rats

Irradiated rats experience a 50% drop in cognitive function. But if the irradiated rats are transplanted with embryonic stem cells, they regain normal cognitive function within 4 months after radiation.

Radiotherapy for brain tumors is limited by how well the surrounding tissue tolerates the treatment. In receiving radiation at levels needed to treat tumors, patients suffer varying degrees of learning and memory impairment that can affect their quality of life.

"It's a progressive, debilitating side effect of cranial irradiation," Limoli said. "Any treatments showing promise at reversing this are worthy of pursuit."

In the UCI study, stem cells were transplanted into the heads of rats that had undergone radiation treatment. They migrated to a brain region known to support the growth of neurons, scientists observed, and developed into new brain cells.

Work is under way to determine how the transplanted stem cells improved cognition: Did they integrate into healthy tissue or did they help repair and support existing brain cells? _SD

The embryonic stem cells (ESCs) used for the UC Irvine study were derived from human embryos. They used basically the same ESC transplant technique for restoring brain function as they used to restore limb function in rats with transected cervical spines. Apparently the rats did not mind receiving ESCs from a different species.