Smith, Leslie A

In animal models, transplantation of CD34 + cells has beneficial effect on cerebral ischemia and recovery from stroke, however, the mechanism underlying cerebrovascular effects of CD34 + cells is poorly understood. In the present study, CD34 + cells were obtained by magnetic cell sorting of rabbit peripheral blood mononuclear cells. Rabbit basilar arteries were exposed to autologous CD34 + cells (~5×10 5 cells) in vitro or in vivo . Arteries treated with endothelial growth medium‐2 (EGM‐2, vehicle) served as controls. Twenty four hours after intracisternal delivery of cells, basilar arteries were isolated and studied. In arteries treated with CD34 + cells either in vivo or in vitro , protein expression of phosphorylated Ser‐473‐Akt and phosphorylated Ser‐1177 endothelial nitric oxide synthase (eNOS) were significantly increased (n = 6, P<0.05), while expressions of eNOS, Akt, inducible NOS, cyclooxygenase‐1 (COX‐1) and COX‐2 were not affected (n = 6, P>0.05). In arteries exposed to CD34 + cells in vitro , cGMP content was significantly augmented (n = 4, P<0.01), whereas cAMP levels remained unaffected (n = 4, P>0.05). Our results suggest that in basilar artery, CD34 + cells stimulate phosphorylation of Akt and eNOS thereby increasing endothelial NO production. These findings may help to explain described therapeutic effect of transplanted CD34 + cells in cerebral circulation.