No abstract

Mesenchymal stem cell (MSC)-mediated tissue regeneration is a promising strategy to treat several neurodegenerative diseases and traumatic injuries of the central nervous system. Bone marrow MSCs have great potential as therapeutic agents, since they are easy to isolate and expand and are capable of producing various cell types, including neural cells. Recently we developed a highly efficient methodology to produce neural stem-like and neural precursor-like cells from mice bone marrow-derived MSCs that eventually differentiate into neuronal- and glial-like cells in vitro. The aim of this study is to further elucidate neural expression profile of neurally induced mesenchymal stem cells (NI-MSCs) and their ability to retain neural differentiation potential when grafted into the intact spinal cord of rats. To this end, we further characterized in vitro and in vivo properties of NI-MSCs by immunocytochemistry, Western blot, ELISA, and immunohistochemistry. Immunocytochemical data demonstrated that NI-MSCs express several mature neural markers such as B3T, GFAP MAP-2, NF-200, and NeuN, which were confirmed through Western blot. ELISA data showed that NI-MSCs release nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). In vivo studies demonstrated that grafted NI-MSCs survived after transplantation into intact spinal cord and produced cells that expressed neural markers. All these data suggest that neurally modified MSCs, induced by recently developed methodology, could be a potential source of cells to replace damaged neurons and glia in injured spinal cord, and/or to promote cell survival and axonal growth of host tissue.

S100betabeta is a calcium binding, neurotrophic protein produced by nonneuronal cells in the nervous system. The pathway by which it enhances neuronal survival is unknown. Here we show that S100betabeta enhances survival of embryonic chick forebrain neurons in a dose-dependent manner. In the presence of suboptimal amounts of S100betabeta, neuronal survival is enhanced by the immunosuppressants FK506 and cyclosporin A at concentrations that inhibit calcineurin, which is present in these cells. Rapamycin, an immunosuppressant that does not inhibit calcineurin, did not enhance cell survival. Cypermethrin, a direct and highly specific calcineurin inhibitor, mimicked the immunophilin ligands in its neurotrophic effect. None of the drugs stimulated neuronal survival in the absence of S100betabeta. In the presence of suboptimal amounts of S100betabeta, FK506, cyclosporin A, and cypermethrin (but not rapamycin) also increased NF-kappaB activity, as measured by immunofluorescence of cells stained with antibody to the active subunit (p65) and by immunoblotting of nuclear extracts. Antioxidant and glucocorticoid inhibitors of NF-kappaB decreased both the amount of active NF-kappaB and the survival of neurons caused by S100betabeta alone or in the presence of augmenting drugs. We conclude that S100betabeta enhances the survival of chick embryo forebrain neurons through the activation of NF-kappaB.

Human MSCs that are neurally modified with this methodology could be a useful source of cells for CNS repair and regeneration.