[Complications and biological risks of neuronal grafts]

Following an experimental stage, considered insufficient by some authors, the first neural grafts on humans were done on Parkinson patients in 1982. Since then, hundreds of patients, mostly with Parkinson disease, have been subjected to grafts. Recently patients suffering from other neurodegenerative diseases or pain of carcinomatous origin have also been grafted. The first results obtained in humans are modest and vary depending on the research groups and methods employed. It must be distinguished between two types of surgery which raise different ethical and scientific problems. First, embryonic neural transplants, in which the effects could be related to a possible actual reinnervation of the striatum. Second, autografts of adrenal medulla, the mechanisms of action of which are still hypothetical. The relative ease of graft technique and their success with the media should not minimize complications and risks. There are three types of known or possible complications: 1 - the complications related to the surgery, 2 - the non-specific complications of the graft itself, that are secondary to the host reaction to transplantation, 3 - the specific graft complications related to relationship established between the grafted cells and the host. In the adrenal medulla autograft, the surgery complications are responsible for an important morbidity and mortality. The immunological and infectious (viral) risks are the most worrying in the embryonic transplants. Even though neuronal grafting can be a technique of the future, great caution is necessary, since intracerebral grafting in Parkinson's disease still is in the experimental field.