[Cell therapy in amyotrophic lateral sclerosis: science and controversy]

Stem cell therapy is seen as a possible alternative for the treatment of different degenerative diseases, among which includes amyotrophic lateral sclerosis (ALS). Despite there being basic research works with this therapy in ALS, the mechanism of action of the implanted cells are still unclear. It is also unclear which type of cells to use (bone marrow, fat, dental pulp, etc.), or the most ideal administration route. Furthermore, clinical trials with mesenchymal stem cells are not very conclusive, therefore it has not been convincingly established as an alternative therapy in ALS or any other neurodegenerative disease. Despite the scientific evidence, several clinical trials have been conducted in the last few years that offer stem cell treatments for neurodegenerative diseases, giving rise to what is known as "cellular tourism". This phenomenon has set off alarms and reactions in the scientific community. The application of these therapies must be performed following the good clinical practice guidelines in research, evidence based methodology and international ethical and scientific recommendations.