Characterization of vascular smooth muscle progenitor cells in human peripheral blood

血管平滑肌细胞（Vascular smooth muscle cells，SMC）通过产生细胞外基质（extracellular matrix，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新生等人类血管疾病中发挥重要作用。人们认为，在人类血管病变中，内膜SMC从中膜迁移，并表现出不成熟和炎性表型。近年来，我们在小鼠主动脉移植模型中发现循环中骨髓来源的平滑肌祖细胞参与了血管新生内膜增生的发病过程，从而推测人外周循环中存在血管平滑肌祖细胞，可能参与了人血管纤维增生性疾病的发生。我们培养人外周血单个核细胞（PBMC）的ECM包被板在SMC培养基和基因表达谱评估细胞表型。我们首次发现了血管平滑肌α-肌动蛋白（SM α-actin）的表达 ...更多信息 RT-PCR法检测外周血PBMC中血管平滑肌细胞（SMC）标志物的表达，提示外周血中存在血管平滑肌祖细胞。低密度（d<1.071mg/mL）PBMC中SM α-actin阳性细胞较多，且不同供体PBMC中SM α-actin表达水平差异较大。从低密度PBMC中培养大的梭形、重叠、SM α-肌动蛋白表达细胞;“MC样纤维肌细胞（FMC）”。培养1个月后，PBMC来源的FMC中SM-α-actin的表达增加。我们通过RT-PCR、Western blotting和抗SM α-actin单克隆抗体（1A 4）的免疫组化证实了血管SM α-actin在PBMC衍生的FMC中的表达。PBMC来源的FMC在体外培养过程中具有良好的增殖能力，并表达主要的SMC标志物：波形蛋白、SM 22 α、SM-1和部分SM-2。此外，它们表达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”存在于人类循环外周血中，它们可能有助于人类血管疾病的发病机制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