Remyelination is the natural repair mechanism in demyelinating disorders such as multiple sclerosis (MS) and it was proposed that it might protect from axonal loss. For unknown reasons, remyelination is often incomplete or fails in MS lesions and therapeutic treatments to enhance remyelination are not available. Recently, the transplantation of exogenous mesenchymal stem cells (MSC) has emerged as a promising tool to enhance repair processes. This included the animal model experimental autoimmune encephalomyelitis (EAE), a commonly used model for the autoimmune mechanisms of MS. However, in EAE it is not clear if the beneficial effect of MSC derives from a direct influence on brain resident cells or if this is an indirect phenomenon via modulation of the peripheral immune system. The aim of this study was to determine potential regenerative functions of MSC in the toxic cuprizone model of demyelination that allows studying direct effects on de- and remyelination without the influence of the peripheral immune system. MSC from three different species (human, murine, canine) were transplanted either intraventricularly into the cerebrospinal fluid or directly into the lesion of the corpus callosum at two time points: at the onset of oligodendrocyte progenitor cell (OPC) proliferation or the peak of OPC proliferation during cuprizone induced demyelination. Our results show that MSC did not exert any regenerative effects after cuprizone induced demyelination and oligodendrocyte loss. During remyelination, MSC did not influence the dynamics of OPC proliferation and myelin formation. In conclusion, MSC did not exert direct regenerative functions in a mouse model where peripheral immune cells and especially T lymphocytes do not play a role. We thus suggest that the peripheral immune system is required for MSC to exert their effects and this is independent from a direct influence of the central nervous system.
Salinas Tejedor L, Berner G, Jacobsen K, Gudi V, Jungwirth N, Hansmann F, Gingele S, Prajeeth CK, Baumgärtner W, Hoffmann A, Skripuletz T, Stangel M. Mesenchymal stem cells do not exert direct beneficial effects on CNS remyelination in the absence of the peripheral immune system. Brain Behav Immun. 2015 Jun. pii: S0889-1591(15)00233-0
There are many types of stem cells, but the hope of MSers is that they will cause repair. In a recent debate on stem cells at the MS Society it was argued that (a) Stem cells have only a modest effect by causing immune modulation (b) Few cells can get into the CNS an (c) They don’t cause much remyelination. In this study they take one type of stem cell and they inject them into the brain of mice with mice with chemical-induce demyelination, which is used to study remyelination drugs and the stem cells do nothing towards repair.
In response to your desires these approaches have already been tried in MS…so are they going to work? Maybe an Maybe not. However, the expectation should not be too unrealistically high.
If they do, things can be better an if they don’t…do not blame the animals.