Parkinson’s researchers are looking for ways to spark the repair mechanisms already in a patient’s brain to fix damage. This strategy is less developed than cell implantation, but it also holds promise. James Fallon and colleagues studied the effects on rat brain of a protein called transforming growth factor alpha (TGF ) a natural peptide found in the body from the very earliest stages of embryonic development onward that is important in activating normal repair processes in several organs, including liver and skin. Fallon’s studies suggest that the brain’s normal repair process may never be adequately triggered in a slowly developing degenerative disease like Parkinson’s and that providing more TGF can turn it on.

Specifically, Fallon found that TGF injected into healthy rat brain causes stem cells in the subventricular zone to proliferate for several days, after which they disappear. But if the researchers make similar injections into rats in which they first damage the nigro-striatal neurons with a toxin called 6-hydroxydopamine a frequently used animal model for Parkinson’s Disease two things happen. After several days of cell proliferation, Fallon observes what he calls a “wave of migration” of the stem cells to the damaged areas, where they differentiate into dopamine neurons. Most importantly, the treated rats do not show the behavioral abnormalities associated with the loss of the neurons. Whether the beneficial effect on symptoms is the result of the newly formed cells or some other trophic effect is not yet entirely clear.