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.