Bone Marrow as a Source of Endothelial Cells and NeuN-Expressing Cells After Stroke

Background and Purpose— After an ischemic event, bone marrow–derived cells may be involved in reparative processes. There is increasing evidence that bone marrow–derived stem cells may be a source of endothelial cells and organ-specific cells. Our objectives were to determine whether bone marrow–derived cells were a source of endothelial cells and neurons after cerebral ischemia. Methods— We transplanted bone marrow from male C57 BL/6-TgN (ACTbEGFP)1Osb mice, which express green fluorescent protein (GFP), into female C57 BL/6J mice. The recipient mice then underwent suture occlusion of the middle cerebral artery (MCA), and bone marrow– derived cells were tracked by GFP epifluorescence and Y chromosome probe. Results— Within 3 days and at 7 and 14 days after MCA occlusion, bone marrow–derived cells incorporated into the vasculature in the ischemic zone and expressed an endothelial cell phenotype. Few bone marrow–derived cells incorporated into the vasculature 24 hours after MCA occlusion. Some bone marrow–derived cells also expressed the neuronal marker NeuN at 7 and 14 days after ischemia. Conclusions— Postnatal vasculogenesis occurs in the brain in the setting of a cerebral infarction. Bone marrow–derived cells are a source of endothelial cells and NeuN-expressing cells after cerebral infarction. This plasticity may be exploited in the future to enhance recovery after stroke.