Many diseases are caused by cells which have died or otherwise need to be replaced, and among them is Parkinson's disease. In that case a specific region in the brain has a lesion which impairs the ability to produce dopamine. Researchers at the University of Wisconsin, Madison have some good, if early news for a potential treatment for that and other diseases.
The most obvious means to cure Parkinson's is to replace the malfunctioning cells, but this much more easily said than done as there are no spare brain cells to transplant. Instead new cells from somewhere else would have to be implanted; specifically pluripotent stem cells. For their work, the researchers harvested the stem cells from the skin of monkeys who suffer Parkinson's. Stem cells can be found throughout your body and researchers have, for some time, been working to induce these adult stem cells to regress to a pluripotent state. The researchers did this with the skin cells, making them into neural cells in the lab, before implanting in the monkeys' brains, where they then developed into the appropriate brain cells. Very importantly, the transplanted cells, having come from the monkeys, were not rejected by their immune system and, after enough time had passed, became indistinguishable from other brain cells.
The only bad news about this research is it is completely proof-of-concept and does not represent any kind of useable treatment yet. Too few cells were transplanted to cure the monkeys and even then, there are many open questions about what will happen to the cells overtime, which will impact any possible treatments to come from this.
Source: University of Wisconsin, Madison