ABSTRACT
RATIONALE: Bone marrow (BM) cells play an important role in physiological and therapeutic neovascularization. However, it remains unclear whether any specific uncultured BM cell populations have higher angiogenic and vasculogenic activities. Moreover, there has been controversy regarding the vasculogenic ability of BM cells. OBJECTIVE: Preliminary flow cytometric analysis showed that CD31, traditionally a marker for endothelial cells, is expressed in certain nonendothelial BM mononuclear cells in both human and mouse. Based on the conserved CD31 expression in the axis of hematopoietic stem/progenitor cells (HSC/HPCs) to endothelial cells, we further sought to determine the comprehensive vasculogenic and angiogenic characteristics of human and mouse BM-derived CD31(+) cells. METHODS AND RESULTS: Flow cytometric analysis demonstrated that all CD31(+) cells derived from BM were CD45(+) and expressed markers for both HSC/HPCs and endothelial cells. Comprehensive gene expression analyses revealed that BM-CD31(+) cells expressed higher levels of angiogenic genes than CD31(-) cells. Endothelial progenitor cells, as well as HSC/HPCs, were almost exclusively confined to the CD31(+) cell fraction, and culture of CD31(+) cells under defined conditions gave rise to endothelial cells. Finally, injection of CD31(+) cells into ischemic hindlimb repaired ischemia, increased expression of angiogenic and chemoattractive factors, and, in part, directly contributed to vasculogenesis, as demonstrated by both 3D confocal microscopy and flow cytometry. CONCLUSIONS: These data indicate that BM-CD31(+) cells represent highly angiogenic and vasculogenic cells and can be a novel and highly promising source of cells for cell therapy to treat ischemic cardiovascular diseases.
Subject(s)
Bone Marrow Cells/physiology , Bone Marrow Transplantation , Ischemia/surgery , Muscle, Skeletal/blood supply , Neovascularization, Physiologic , Platelet Endothelial Cell Adhesion Molecule-1/metabolism , Angiogenic Proteins/metabolism , Animals , Biomarkers/metabolism , Bone Marrow Cells/immunology , Bone Marrow Cells/metabolism , Cells, Cultured , Chemotactic Factors/metabolism , Disease Models, Animal , Flow Cytometry , Gene Expression Regulation , Green Fluorescent Proteins/biosynthesis , Green Fluorescent Proteins/genetics , Hindlimb , Humans , Immunophenotyping , Ischemia/immunology , Ischemia/metabolism , Ischemia/physiopathology , Leukocyte Common Antigens/metabolism , Mice , Mice, Inbred C57BL , Mice, Nude , Mice, Transgenic , Microscopy, Confocal , Neovascularization, Physiologic/genetics , Phenotype , Time FactorsABSTRACT
Bone marrow-derived mononuclear cells (BMNCs) have been shown to effectively treat ischemic cardiovascular diseases. Because diabetic neuropathy (DN) is causally associated with impaired angiogenesis and deficiency of angiogenic and neurotrophic factors in the nerves, we investigated whether DN can be ameliorated by local injection of BMNCs. Severe peripheral neuropathy, characterized by a significant decrease in the motor and sensory nerve conduction velocities (NCVs), developed 12 weeks after the induction of diabetes with streptozotocin in rats. The injection of BMNCs restored motor and sensory NCVs to normal levels and significantly improved vascular density and blood flow in diabetic nerves over 4 weeks. Fluorescent microscopic observation revealed that DiI-labeled BMNCs preferentially engrafted in sciatic nerves. Whole-mount fluorescent imaging and confocal microscopic evaluation demonstrated that many of the BMNCs localized following the course of the vasa nervorum in close proximity to blood vessels without incorporation into vasa nervorum as endothelial cells at a detectable level. Real-time reverse transcription-polymerase chain reaction analysis showed that the levels of angiogenic and neurotrophic factors were significantly increased in the nerves by BMNC injection. Local transplantation of BMNCs improved experimental DN by augmenting angiogenesis and increasing angiogenic and neurotrophic factors in peripheral nerves. These findings suggest that BMNC transplantation may represent a novel therapeutic option for treating DN.
