Characterization of vascular smooth muscle progenitor cells in human peripheral blood

血管平滑肌细胞（SMC）通过产生细胞外基质（ECM）蛋白和增殖，在动脉粥样硬化、血管成形术后再狭窄、移植血管病变和血管生成等人类血管疾病中发挥重要作用。人们一直认为，内膜SMC是从介质中迁移过来的，它们在人类血管病变中表现出不成熟和炎症表型。最近，我们在小鼠主动脉移植模型中证实循环骨髓来源的平滑肌祖细胞参与了新生内膜增生的发病机制，从而推测血管平滑肌祖细胞可能存在于人体外周循环中，参与了人类血管纤维增生性疾病的发生。我们在smc培养基中培养人外周血单核细胞（PBMC），并通过基因表达谱评估细胞表型。我们首次通过RT-PCR发现了血管平滑肌α-肌动蛋白（SM α-肌动蛋白）…More在循环PBMC中的表达，表明“血管平滑肌祖细胞”在人体外周循环中存在。SM α-actin阳性细胞在低密度PBMC组中大量出现（d<1.071 mg/mL），且SM α-actin在不同供体PBMC中的表达水平差异较大。大梭形，层状，表达SM α-肌动蛋白的细胞；从低密度PBMC中培养“mc样纤维肌肉细胞（FMC）”。在培养1个月后，pbmc衍生的FMC中SM-α-actin的表达增加。我们通过RT-PCR、Western blotting和SM α-actin特异性单克隆抗体免疫染色证实了血管SM α-actin在pmc驱动的FMC中的表达（1A4）。pbmc衍生的FMC具有良好的增殖能力和表达SMC主要标志物的能力；vimentin, SM22α, SM-1，和部分SM-2。此外，它们还表达ECM蛋白、i型和iii型胶原。这些结果提供了一个新的概念，即“血管平滑肌祖细胞”存在于人类循环的外周血中，它们可能参与人类血管疾病的发病和管腔血流的血管生成

Vascular smooth muscle cells (SMC) play an important role in human vascular diseases, including atherosclerosis, restenosis after angioplasty, transplant vasculopathy, and angiogenesis by producing extracellular matrix (ECM) proteins and proliferation. It has been believed that intimal SMC are migrated from media and they exhibit immature and inflammatory phenotype in human vascular lesions. Recently, we have demonstrated that circulating bone marrow-derived smooth muscle progenitor cells are involved in pathogenesis of neointimal hyperplasia in mouse aortic transplantation model, thus we gypothesized that vascular smooth muscle progenitor cells could exist in human peripheral circulation, contributing to human vascular fibroproliferative deseases. We cultured human peripheral blood mononuclear cells (PBMC) on ECM-coated plates in SMC-culture media and evaluated cellular phenotype by gene expression profiles. We first discovered expression of vascular smooth muscle α-actin (SM α-actin) … More , an essential vascular SMC marker, in circulating PBMC by RT-PCR, indicating the presence of "vascular smooth muscle progenitor cells" in human peripheral circulation. The SM α-actin positive cells were abundant in low-density PBMC faction (d<1.071 mg/mL) and the expression level of SM α-actin in PBMC varied substantially among donors. Large spindle-shaped, overlayered, SM α-actin-expressing cells ; "MC-like fibromuscular cells (FMC)" were cultured from the low-density PBMC. The SM-α-actin expression in PBMC-derived FMC increased during one month culture period. We confirmed expression of vascular SM α-actin in PBMC-dirived FMC by RT-PCR, Western blotting and immunostaining with a specific monoclonal antibody against SM α-actin (1A4). The PBMC-derived FMC had great ability of proliferation and express major SMC markers ; vimentin, SM22α, SM-1, and partially SM-2 during in vitro culture. Furthermore, they express ECM proteins, type-I and type-III collagen. These results provide a novel concept that "vascular smooth muscle progenitor cells" exist in human circulating peripheral blood and they could potentially contribute to pathogenesis of human vascular diseases and angiogenesis from luminal blood stream Less