Stem cell therapy for ALS: Hope and reality a discussion paper from the executive of the European ALS consortium

Background All are agreed that there is pressing need for an effective treatment for Amyotrophic Lateral Sclerosis (ALS; MND). Such treatment may derive from a combination of therapeutic strategies aimed at different aspects of the disorder, and might include drugs directed at the initial, intermediate or terminal cascade of events leading to cell death, as well as the use of stem cells to replace dead motor neurons, or to protect those that remain. The attraction of cell implantation or transplantation is that it might help to overcome the inability of the CNS to replace lost neurons. It is also clear that neural implantation will yield little benefit if the donor cells fail to integrate functionally into the recipient CNS circuitry. In this respect, ALS poses an especially difficult problem. The recent breakthroughs in stem cell research might nevertheless provide possibilities for neural implantation and cell replacement therapy for patients with ALS. The potential impact of these new approaches to neurodegenerative diseases has been emphasised by the many experiments using human foetal cell grafts in patients affected by Parkinson's and Huntington's disease. Clinical benefits in Parkinson's disease seem to be associated with integration of the donor cells into the recipient brain. Despite promising results, however, significant constraints have hampered the use of foetal cells for neural implantation and transplantation. Besides ethical concerns, the viability, purity, and final destiny of the foetal tissue have not been completely defined. Foetal cells are, in addition, post-mitotic and cannot be expanded or stored for long periods, necessitating close synchronisation of tissue donation and neurosurgery.