[Transplantation of myelinating cells as regenerative therapy for multiple sclerosis - experimental basis and present state of clinical studies].

Currently available therapies for multiple sclerosis (MS) delay disease progression via immunomodulation or immunosuppression. A persisting neurological deficit is mostly irreversible. Thus, a reparative treatment is urgently warranted. After positive results in animal models, clinical trials to promote endogenous remyelination with intravenous immunoglobulins (IVIg) or the growth factor IGF-1 were performed, unfortunately without clinical improvement. Another possibility to achieve remyelination is the transplantation of myelinating cells into the central nervous system. Proof of principle and demonstration of the functionality were shown in numerous experiments, and a first clinical trial in patients with MS has started. Although there are still several open questions, many are specific to MS and can not be answered in an animal model. This first trial will show if cell transplantation is a feasible concept in MS and whether the transplanted cells will survive and form new myelin. Schwann cells are currently the most promising cells to be transplanted, due to the advantages of an autologous transplantation from the patient's sural nerve biopsy, possibility to expand the cells in culture, and the possibility that they may escape the ongoing inflammatory reaction in MS. Other cell types are available, including stem cells, which are in the centre of a lively discussion. The results of the ongoing trial must be awaited before other transplant studies are performed to tackle other yet unresolved problems. At the time, it seems unlikely that cell transplantation will become clinical practice in the near future.