Marrow stromal cell transplantation in stroke and traumatic brain injury.

There is a paucity of therapies for most central nervous system (CNS) disorders. Bone marrow stromal cells (MSCs) are a mixed cell population, including stem and progenitor cells, and are currently a strong candidate for cell-based therapy in "brain attack", including stroke, and traumatic brain injury (TBI), since they are easily isolated and can be expanded in culture from patients without ethical and technical problems. Although it has been suggested that trans-differentiation of MSCs into cells of neural lineage may occur in vitro, no one has yet observed that MSCs give rise to fully differentiated and functional neurons in vivo. The overwhelming body of data indicate that bioactive factors secreted by MSCs in response to the local environment underlie the tissue restorative effects of MSCs. The MSCs that are employed in this therapy are not necessarily stem cells, but progenitor and differentiated cells that escape immune system surveillance and survive in the CNS even for transplantation of allogeneic or xenogeneic MSCs. The injured CNS is stimulated by the MSCs to amplify its intrinsic restorative processes. Treatment of damaged brain with MSCs promotes functional recovery, and facilitates CNS endogenous plasticity and remodeling. The current mini-review is mainly based on our data and focuses on possible cellular and molecular mechanisms of interaction of MSCs with glia, neurons and vessels after brain attack. The transplantation of MSCs opens up new avenues of cell therapy and may provide an effective treatment for various CNS diseases.