Human Stem Cells Treating Mouse Multiple Sclerosis
Cleveland, Ohio -
The possibility of stem cells treating multiple sclerosis is very enticing.
This comes from two angles. The first is that various type of stem cells either directly can heal injured nervous system tissue or produce various growth factors that allow the injured tissue to heal itself. For example, it has been published that mesenchymal stem cells can differentiate into oligodendrocytes, which make myelin. It has also been reported that stem cells produce growth factors such as IGF-1, which when administered into injured central nervous system tissue cause its repair. The second reason why stem cell therapy for multiple sclerosis is appealing is that various types of stem cells, such as mesenchymal stem cells, are known to have immune modulating properties. In other words, since multiple sclerosis is mediated by an abnormal T cell response, there is a possibility that therapy using cells such as mesenchymal stem cells may actually not only heal the damage that has occurred, but also address the root cause of the damage.
There was a recent paper (Bai et al. Human bone marrow-derived mesenchymal stem cells induce Th2-polarized immune response and promote endogenous repair in animal models of multiple sclerosis) which used human bone marrow mesenchymal stem cells to treat mice which were induced to have a disease that is similar to multiple sclerosis.
The scientists used two types of mouse multiple sclerosis. The first is a progressive type, in which the MOG peptide was used to ”immunize” B6 mice, and the second is a relapse-remitting type in which another myelin component called PLP was used to “immunize” SJL mice. What this means is that the mice develop an immune response against components of the myelin, and subsequently exhibit a disease that resembles clinical multiple sclerosis.
Administration of human bone marrow derived mesenchymal stem cells into these mice resulted in reduction in disease progression, as well as healing at the cellular level. Increased numbers of oligodendrocytes (the cells that make myelin) were observed in the mice that recieved stem cell therapy. Interestingly, the autoimmune response seemed to be suppressed, well at least the inflammatory component of it, since reduction of interferon gamma and interleukin-17 was seen, which are both associated with poor patient prognosis, whereas elevated levels of interleukin-4, an antiinflammatory agent were seen in the treated mice.
This paper was particularly interesting since it demonstrated that human mesenchymal stem cells work in mice, not only for modulating the immune system but also for accelerating repair. Although not assessed, it is possible that the mesenchymal stem cells were also increasing levels of T regulatory cells. This is something that should be performed in future studies.