To date, there has not been a single study – to our knowledge – that has compared different types of stem cells, concerning safety and efficacy, particularly in patients with SMA.

There are currently many types of stem cells available to use in different conditions including embryonic stem cells, mesenchymal stem cells (ex. bone marrow and umbilical cord stem cells), hematopoietic stem cells, neural stem cells, as well as many other sources (6).

However, when looking at other similar neurodevelopmental disorders and at different stem cell therapy trials, the most feasible-to-obtain and safely-used stem cells that have been used and tested in people with other neurological conditions are the mesenchymal stem cells such as those obtained from either umbilical cord-derived samples, both cord blood and cord tissue, or bone marrow stem cells. These two types provide the best results in neurological conditions since they easily cross the blood-brain barrier, to reach the brain and the spinal cord, and have the lowest possible side effects (7).

Studies are also currently testing the use of genetically-modified stem cells that can be acquired from SMA patients to allow for self-reinjection of stem cells that have been modified to harbor normal SMN protein. These cells are known as induced pluripotent stem cells (iPSCs). The aim of this technique is to prevent possible side effects or allergic reactions due to the transplantation of “foreign” cells from donors other than the patients themselves. However, this technique is still not clinically applicable in the medical field (8).

Therefore, our work is currently still based on one of the only clinical studies testing stem cell therapy in SMA patients which found that mesenchymal stem cell therapy provided visible benefits when administered using two concomitant routes of administration; both intravenous and intrathecal routes; versus when they used solitary intrathecal route (10).

These results have contributed to establishing our current method of dual-type stem cell administration.