Exploiting nonneural cells to rebuild the nervous system: From bone marrow to brain

Bone marrow, in addition to hematopoietic precursors, contains cells that are considered stem cells of nonhematopoietic tissues. These cells are referred to as marrow stromal cells or mesenchymal stem cells. Marrow stromal cells, because of their ability to survive, integrate, and migrate within the central nervous system, can be used as an alternative source of cells for neural transplantation and repair. They can be expanded rapidly in culture and can be induced to express markers of neural cells. Moreover, implanted into the developing brain, these cells can integrate without disrupting the host brain architecture and can assume the fate of neural cells. They can be genetically transduced and can elaborate transgene products. Because large numbers of stromal cells can be obtained from small aspirates of bone marrow, these cells are potentially useful for treating a variety of neurological diseases.