Intracarotid injection of fluorescence activated cell-sorted CD49d-positive neural stem cells improves targeted cell delivery and behavior after stroke in a mouse stroke model

Background and Purpose - Intravascular delivery of neural stem cells ( NSCs) after stroke has been limited by the low efficiency of transendothelial migration. Vascular cell adhesion molecule- 1 is an endothelial adhesion molecule known to be upregulated early after stroke and is responsible for the firm adhesion of inflammatory cells expressing the surface integrin, CD49d. We hypothesize that enriching for NSCs that express CD49d and injecting them into the carotid artery would improve targeted cell delivery to the injured brain. Methods - Mouse NSCs were analyzed for the expression of CD49d by fluorescence activated cell sorting. A CD49d- enriched ( CD49d(+)) (> 95%) and - depleted ( CD49d(-); <5%) NSC population was obtained by cell sorting. C57/ B16 mice underwent left- sided hypoxia - ischemia surgery and were assigned to receive 3 X 10(5) CD49d(+), CD49d(-) NSCs, or vehicle injection into the left common carotid artery 48 hours after stroke. Behavioral recovery was measured using a rotarod for 2 weeks after cell injection. Results - Fluorescence activated cell sorting analysis revealed 25% CD49d(+) NSCs. In a static adhesion assay, NSCs adhered to vascular cell adhesion molecule- 1 in a dose- dependent manner. Significantly more NSCs were found in the cortex, the hippocampus, and the subventricular zone in the ischemic hemisphere in animals receiving CD49d(+) NSCs as compared with CD49d - NSCs ( P < 0.05). Animals treated with CD49d(+) cells showed a significantly better behavioral recovery as compared with CD49d(-) and vehicle- treated animals. Conclusions - We show that enrichment of NSCs by fluorescence activated cell sorting for the surface integrin, CD49d, and intracarotid delivery promotes cell homing to the area of stroke in mice and improves behavioral recovery.