BACKGROUND: Multipotent adult progenitor cells (MAPCs) from the bone marrow have been shown to differentiate into neurons.OBJECTIVE: To observe migration, survival, and neuronal-like differentiation of MAPCs by tail vein injection.DESIGN, TIME AND SETTING: Randomized, controlled experiment of neural tissue engineering was performed at the Laboratory for Cardio-Cerebrovascular Disease, Hospital of Integrated Traditional and Western Medicine, Tongji Medical College of Huazhong University of Science and Technology between September 2006 and August 2007.MATERIALS: Eighty Sprague Dawley rats, 3-6 months old, underwent cerebral ischemia/reperfusion by thread technique, and were randomly divided into model and MAPCs groups (n = 40).METHODS: Mononuclear cells were harvested from bone marrow using the Ficoll-Paque density gradient centrifugation method. After removing CD45 and glycophorin A-positive cells (GLYA+) with immunomagnetic beads, CD45 GLYA adult progenitor cells were labeled with bromodeoxyuridine (5-bromo-2-deoxyuridine, BrdU). A total of 1 mL cell suspension, containing 5 ×106 MAPCs, was injected into the MAPCs group through the tail vein. A total of 1 mL normal saline was injected into the model rats.MAIN OUTCOME MEASURES: After 60 days, BrdU and neuron-specific enolase double-positive cells were observed using immunofluorescence. Cell morphology was observed under electron microscopy, and nerve growth factor mRNA was measured through RT-PCR. In addition, rat neurological functions were measured with behavioral tests.RESULTS: Immunofluorescence revealed that MAPCs positive for BrdU and neuron specific enolase were found surrounding the ischemic focus in the MAPCs group. Microscopic observation suggested that MAPCs-derived neuronal-like cells connected with other nerve cells to form synapses, Compared with the model animals, the level of nerve growth factor mRNA was significantly upregulated in rats injected with MAPCs (P < 0.05). In addition, rats in the MAPCs group performed better in behavioral tests than the model group on days 28 and 60 (P < 0.05).CONCLUSION: Transplanted MAPCs migrated to the ischemic region, survived, and differentiated into neuronal-like cells, resulting in stimulation of nerve growth factor mRNA and improved neurological function in ischemic rats.