With Parkinsons a degeneration of cell groups takes place and from a conceptual perspective, the perfect treatment would be to replace the lost cells. The big drawback in the search for a suitable cell is to find one that survives for a lengthy period within the brain, that integrates well into the brain structures in order to comply with a series of functions and one that is not rejected by the organism of the patient. At the University Hospital a line of investigation is being carried out that is based on experimenting with stem cells having the ability to transform themselves into neurones and incorporate themselves into the brain. Two types of cells are currently being tested: one type consists of adult bone marrow stem cells. The aim is to obtain dopaminergic neurones from adult bone marrow stem cells. The next step will be to test to see if these neurones are able, once implanted in the brain, to ameliorate Parkinsonian symptoms in animals. Motor system recovery,The second source of donor cells is cell cultures from the carotid body. This research was initiated five years ago in animals which had carotid body cell aggregates implanted in their brain. The programme's running tests on twelve macaco monkeys (of the Cebidae family) is now coming to an end and it has been shown that motor recovery has been maintained over a period of twelve months. These animals show a moderate improvement in Parkinsonian symptoms, and efforts have thus been centred on achieving enhanced motor performance. This is why these cells are being cultured and isolated in order to effect motor recovery on implantation into the brain. Laboratory data suggest that there exists a population of immature neural cells that grow very well in cell cultures and can serve as an efficacious source for their implantation. The next stage will be to find out if these cells cultivated in the carotid body of animals also exist in the human carotid body. If it turns out that both cellular types have the same characteristics and there is a good response at an experimental level, the treatment can be transferred to humans. ,But it should be made clear that the lines of investigation in cellular therapy are not directed at curing the disease but that, in some patients, it can be observed that clinical improvement can be superior to that achieved with other, alternative treatments. Although not attempting a cure for the ailment, it is possible to improve many of the motor deficits of the patients and even reverse the illness to more initial stages. As long as the cause of the disease is unknown, it cannot be cured.