Smith, Leslie A

Mobilization of hematopoietic progenitor cells is predictive of functional recovery in stroke. In the present study, alterations in progenitor cell counts were studied in an experimental model of subarachnoid hemorrhage (SAH)‐induced cerebral vasospasm in rabbits. Injection of autologous arterial blood into cisterna magna resulted in significant vasospasm of the basilar arteries forty eight hours following injection. Concomitantly, the number of hematopoietic progenitor cells (CD34 + cells) and CD34 + /Flk‐1 + cells, believed to be enriched in endothelial progenitor cells (EPCs), were significantly increased in the peripheral blood. The levels of the chemokine stromal cell‐derived factor‐1α (SDF‐1α), known to play a key role in the recruitment and retention of CXCR4 + ‐progenitor cells, significantly increased in the plasma of rabbits subjected to SAH. However, levels of SDF‐1α in the cerebrospinal fluid as well as the content of SDF‐1α in the spastic basilar arteries remained unaffected forty eight hours after SAH. In summary, cerebral vasospasm was accompanied by mobilization of hematopoietic progenitor cells and EPCs. We speculate that the pathogenesis of cerebral vasospasm following SAH may be mediated, in part, by impaired recruitment and homing of CXCR4 + ‐ progenitor cells.