Turning blood into brain: Cells bearing neuronal antigens generated in vivo from bone marrow

Bone marrow stern cells give rise to a variety of hematopoietic Lineages an d repopulate the blood throughout adult Life. We show that, in a strain of mice incapable of developing colts of the myeloid and Lymphoid lineages,tra nsplanted adult bone marrow cells migrated into the brain and differentiate d into cells that expressed neuron-specific antigens. These findings raise the possibility that bone marrow-derived cells may provide an alternative s ource of neurons in patients with neurodegenerative diseases or central ner vous system injury.