Identification of neuronal outgrowth cells from peripheral blood of stroke patients

Objective Recent studies have identified a subset of outgrowth cell population with endothelial phenotype in long-term cultures of peripheral blood mononuclear cells. The concept that peripheral blood–derived cells participate in neuronal regeneration remains highly controversial, and no specific cell type has been identified. In this study, we undertook to characterize outgrowth cells in the peripheral blood culture from stroke patients. Methods Mononuclear cells were isolated from the peripheral blood of 30 acute stroke patients, 20 risk factor–only subjects, and 20 healthy volunteers. The isolation frequency of outgrowth cells was measured during the 2 months of culture. The outgrowth cells were characterized by in vitro cultures and in vivo model of transplantation into the ischemic rat brain. Results Outgrowth cells could be more efficiently isolated from stroke patients (80%) than risk factor–only (30%) and healthy groups (10%). Outgrowth cells were more detected in the patients with greater National Institute of Health Stroke Scale scores (p = 0.023). They exhibited heterogenous populations with different morphologies, for example, cobblestone, palisading, or branching features. Two different types of outgrowth cells were identified: endothelial; neuronal, according to their morphological characteristics; and protein or gene expression profiles. The transplanted neuronal outgrowth cells survived in the ischemic rat brains over 6 months after transplantation. Targeted migration of the transplanted cells was seen in the ischemic brains with phenotypes of neuronal phenotypes. Interpretation The feasibility of extracting and culturing neuronal outgrowth cells in large numbers suggests that such autologous cells will be useful for applications ranging from basic research to cell-based therapy. Ann Neurol 2008