Circulating smooth muscle progenitor cells in arterial remodeling

The proliferation and migration of vascular smooth muscle cells (SMCs) from the media toward the intimal layer are key components in vascular proliferative diseases. In addition, the differentiation of circulating bone marrow-derived mononuclear cells (BMMCs) into SMCs has been described to contribute to lesion progression in experimental models of atherosclerosis, transplant arteriosclerosis, and neointima formation. In vitro, CD14⁺ BMMCs from peripheral blood acquire a spindle-shaped phenotype and express specific SMC markers in response to platelet-derived growth factor-BB. However, the ‘trans-differentiation’ capacity of BMMCs into definitive SMCs in vivo remains a highly controversial issue. Whereas SMCs within atherosclerotic plaques have been demonstrated to be exclusively of local origin, more severe injury models have shown a wide diversity of SMCs or smooth muscle-like cells derived from BMMCs. In hindsight, these discrepancies may be attributed to methodological differences, e.g., the use of high-resolution microscopy or the specificity of the SMC marker proteins. In fact, the analysis of mouse strains that express marker genes under the control of a highly specific smooth muscle-myosin heavy chain (SM-MHC) promoter and a time-course analysis on the dynamic process of neointima formation have recently shown that BMMCs temporarily express α-smooth muscle actin, not SM-MHC. Additionally, BM-derived cells disappear from the neointimal lesion after the inflammatory response to the injury has subsided. Although CD14⁺/CD68⁺ have important paracrine effects on arterial lesion progression, BMMCs account for more of the ‘SMC-like macrophages’ than the highly ‘trans-differentiated’ and definitive SMCs in vivo. This article is part of a special issue entitled, "Cardiovascular Stem Cells Revisited".     

Vascular smooth muscle progenitor cells: building and repairing blood vessels

Molecular pathways that control the specification, migration, and number of available smooth muscle progenitor cells play key roles in determining blood vessel size and structure, capacity for tissue repair, and progression of age-related disorders. Defects in these pathways produce malformations of developing blood vessels, depletion of smooth muscle progenitor cell pools for vessel wall maintenance and repair, and aberrant activation of alternative differentiation pathways in vascular disease. A better understanding of the molecular mechanisms that uniquely specify and maintain vascular smooth muscle cell precursors is essential if we are to use advances in stem and progenitor cell biology and somatic cell reprogramming for applications directed to the vessel wall.     

Towards the therapeutic use of vascular smooth muscle progenitor cells

Recent advances in the development of alternative proangiogenic and revascularization processes, including recombinant protein delivery, gene therapy, and cell therapy, hold the promise of greater efficacy in the management of cardiovascular disease in the coming years. In particular, vascular progenitor cell-based strategies have emerged as an efficient treatment approach to promote vessel formation and repair and to improve tissue perfusion. During the past decade, considerable progress has been achieved in understanding therapeutic properties of endothelial progenitor cells, while the therapeutic potential of vascular smooth muscle progenitor cells (SMPC) has only recently been explored; the number of the circulating SMPC being correlated with cardiovascular health. Several endogenous SMPC populations with varying phenotypes have been identified and characterized in the peripheral blood, bone marrow, and vascular wall. While the phenotypic entity of vascular SMPC is not fully defined and remains an evolving area of research, SMPC are increasingly recognized to play a special role in cardiovascular biology. In this review, we describe the current approaches used to define vascular SMPC. We further summarize the data on phenotype and functional properties of SMPC from various sources in adults. Finally, we discuss the role of SMPC in cardiovascular disease, including the contribution of SMPC to intimal proliferation, angiogenesis, and atherosclerotic plaque instability as well as the benefits resulting from the therapeutic use of SMPC.     

辛伐他汀对大鼠平滑肌祖细胞和内皮祖细胞增殖的影响

目的 观察辛伐他汀对平滑肌祖细胞(SPC)和内皮祖细胞(EPC)增殖的影响,筛选新一代包被洗脱支架药物. 方法 采用密度梯度离心法从大鼠骨髓获取单个核细胞,将其接种在纤维连接素包被培养板,加入小同浓度辛伐他汀(0.01～10.00μmol/L)培养6～48 h后,平滑肌肌动脉蛋白免疫荧光染色鉴定骨髓源性SPC,激光共聚焦显微镜鉴定异硫氰酸荧光素结合的植物凝集素(FITC-UEA-I)和DiI结合的乙酰化低密度脂蛋白(DiI-acLDL)双染阳性细胞为正在分化的EPC,并在倒置荧光显微镜下计数. 结果 辛伐他汀显著抑制骨髓源SPC增殖,0.01μmol/L辛伐他汀作用24 h,SPC数量减少了(5.8±3.1)%(对照组与0.01μmol/L辛伐他汀组分别为4070±184与3833±126,P<0.05).辛伐他汀可促进EPC增殖,其促进作用随辛伐他汀浓度增加及作用时间延长而增加,1.00μmol/L辛伐他汀作用24 h EPC数量增加(2.0±0.1)倍(对照组与1 μmol/L辛伐他汀组分别为1249±146与3762±138,P<0.01). 结论 辛伐他汀抑制SPC增殖,促进EPC增殖,局部应用有抑制再狭窄和促进损伤血管再内皮化可能.     

辛伐他汀对大鼠平滑肌祖细胞和内皮祖细胞黏附的不同影响

目的：观察辛伐他汀对平滑肌祖细胞（SPC）和内皮祖细胞（EPC）黏附的影响,筛选新一代用于包被洗脱支架的药物。方法：采用密度梯度离心法获取大鼠骨髓单个核细胞,重悬于SPC培养基或EPC培养基,接种在纤维连接素包被的培养板,以平滑肌肌动蛋白免疫荧光染色鉴定骨髓源性SPC,以激光共聚焦显微镜鉴定的异硫氰酸荧光素-荆豆凝集素-Ⅰ（FITC-UEA-Ⅰ）和Dil标记的乙酰化低密度脂蛋白（DiI-acLDL）双染阳性细胞为正在分化的EPC。分别收集培养8 d的SPC和EPC,加入不同浓度辛伐他汀（0,0.01,0.1,1,10μmol/L）培养24 h。采用贴壁法检测SPC和EPC黏附能力。结果：辛伐他汀显著抑制SPC黏附,0.01μmol/L辛伐他汀作用24h,黏附SPC数量较对照组（0μmol/L）明显减少[（52±4）个∶（59±5）个,n=5,P〈0.05]。与SPC相反,辛伐他汀显著促进EPC黏附,其促进作用随辛伐他汀浓度升高而明显增加,1.0μmol/L达最大效应,与对照组相比显著增加[（39±5）个∶（12±3）个,n=5,P〈0.01]。结论：辛伐他汀选择性抑制平滑肌祖细胞黏附,促进内皮祖细胞黏附,其双向调节作用呈浓度依赖性,局部应用有促进损伤血管再内皮化和抑制新内膜过度增生的可能。     

辛伐他汀对大鼠平滑肌祖细胞和内皮祖细胞分化的不同影响

目的:观察辛伐他汀对平滑肌祖细胞(SPC)和内皮祖细胞(EPC)分化的影响。方法:采用密度梯度离心法获取大鼠骨髓单个核细胞,将其接种在纤维连接素包被培养板,加入不同浓度辛伐他汀(0.01～10μmol/L)培养8d。采用平滑肌肌动蛋白免疫荧光染色鉴定骨髓源性SPC,激光共聚焦显微镜鉴定FITC-UEA-Ⅰ和DiI-acLDL双染阳性细胞为正在分化的EPC,并在倒置荧光显微镜下计数。结果:辛伐他汀显著抑制骨髓单个核细胞分化为SPC。0.01μmol/L辛伐他汀组与对照组SPC数量分别为79±5对85±4(P0.05)。辛伐他汀显著促进骨髓单个核细胞向EPC分化,其促进作用随辛伐他汀浓度升高而增加,在1.0μmol/L达最大效应。1μmol/L辛伐他汀组与对照组EPC数量分别为87±5对39±4(P0.01)。结论:辛伐他汀选择性抑制骨髓单个核细胞向SPC分化,促进其向EPC分化,局部应用有促进损伤血管再内皮化和抑制新生内膜过度增生的可能。     

辛伐他汀对大鼠平滑肌祖细胞和内皮祖细胞迁移的影响

目的观察辛伐他汀对平滑肌祖细胞(smooth muscle progenitor cell,SPC)和内皮祖细胞(endothelialprogenitor cell,EPC)迁移的影响,筛选新一代包被洗脱支架药物。方法采用密度梯度离心法获取大鼠骨髓单个核细胞,重悬于SPC培养基或EPC培养基,接种在纤维连接素包被培养板,平滑肌肌动蛋白免疫荧光染色鉴定骨髓源性SPC,激光共聚焦显微镜鉴定Dil标记乙酰化低密度脂蛋白(DiI-acLDL)和FITC标记的荆豆凝集素Ⅰ(FITC-UEA-Ⅰ)双染阳性细胞为正在分化的EPC。分别收集培养8 d的SPC和EPC,加入不同浓度辛伐他汀(0,0.01,0.1,1,10μmol/L)培养24 h。采用改良Boyden小室检测SPC和EPC迁移能力。结果辛伐他汀显著抑制SPC迁移,0.01μmol/L辛伐他汀作用24 h,迁移SPC数量减少,0.01μmol/L辛伐他汀组与对照组SPC迁移比较,差异有统计学意义(39±3 vs.44±3,n=5,P0.05)。与SPC相反,辛伐他汀显著促进EPC迁移,其促进作用随辛伐他汀浓度升高而增加,1.0μmol/L时达最大效应,1.0μmol/L辛伐他汀组与对照组EPC计数比较,差异有统计学意义(37±5 vs.6±3,n=5,P0.01)。结论辛伐他汀选择性抑制SPC迁移,促进EPC迁移,其双向调节作用呈浓度依赖性,局部应用有促进损伤血管再内皮化和抑制新内膜过度增生的可能。     

辛伐他汀对大鼠平滑肌祖细胞和内皮祖细胞分化的不同影响

目的：观察辛伐他汀对平滑肌祖细胞（SPC）和内皮祖细胞（EPC）分化的影响。方法：采用密度梯度离心法获取大鼠骨髓单个核细胞,将其接种在纤维连接素包被培养板,加入不同浓度辛伐他汀（0．01～10μmol／L）培养8d。采用平滑肌肌动蛋白免疫荧光染色鉴定骨髓源性SPC,激光共聚焦显微镜鉴定FITC—UEA—I和Di I-acLDL双染阳性细胞为正在分化的EPC,并在倒置荧光显微镜下计数。结果：辛伐他汀显著抑制骨髓单个核细胞分化为SPC。0．01μmol／L辛伐他汀组与对照组SPC数量分别为79±5对85±4（P〈0．05）。辛伐他汀显著促进骨髓单个核细胞向EPC分化,其促进作用随辛伐他汀浓度升高而增加,在1．0μmol／L达最大效应。1μmol／L辛伐他汀组与对照组EPC数量分别为87±5对39±4（P〈0．01）。结论：辛伐他汀选择性抑制骨髓单个核细胞向SPC分化,促进其向EPC分化,局部应用有促进损伤血管再内皮化和抑制新生内膜过度增生的可能。     

Methylglyoxal production in vascular smooth muscle cells from different metabolic precursors

Methylglyoxal (MG), a metabolic by-product, reacts with certain proteins to yield irreversible advanced glycation end products (AGEs) and increases oxidative stress that causes the pathophysiological changes in diabetes, hypertension, and aging. Although MG production from glucose has been well documented, the contribution of other intermediates of different metabolic pathways to MG formation is far less known. Our aim was to determine and compare the formation of MG, MG-induced AGE, N(epsilon)-carboxyethyl-lysine (CEL), inducible nitric oxide synthase (iNOS), nitric oxide, and peroxynitrite from different metabolic precursors in cultured rat aortic vascular smooth muscle cells (VSMCs). High-performance liquid chromatography was used to determine MG levels, whereas nitrite + nitrate, indicators of nitric oxide production, and peroxynitrite levels were measured with specific assay kits. The CEL and iNOS were detected using immunocytochemistry. There was a concentration-dependent increase in MG levels in VSMCs after 3-hour incubation with 5, 15, and 25 mmol/L of D-glucose, fructose, or aminoacetone. Aminoacetone produced a 7-fold increase in MG levels above the basal value followed by fructose (3.9-fold), D-glucose (3.5-fold), acetol (2.8-fold), and sucrose (2.3-fold) after a 3-hour incubation with 25 mmol/L of each precursor. L-Glucose, 3-O-methylglucose, and mannitol had no effect on MG production. All precursors, except l-glucose, 3-O-methylglucose and mannitol, increased CEL. Aminoacetone, D-glucose, and fructose significantly increased iNOS, nitrite/nitrate, and peroxynitrite levels. In conclusion, aminoacetone is the most potent precursor of MG production in VSMCs, followed by fructose and d-glucose. This could have important implications in relation to high dietary fructose and protein intake.     

高糖对成人外周血平滑肌祖细胞功能的影响

目的观察不同浓度葡萄糖对体外培养成人外周血平滑肌祖细胞（smooth muscle progenitor cells,SPCs）增殖、迁移和黏附能力的影响。方法采用密度梯度离心法从健康成人外周血获取单个核细胞,培养12d后,采用流式细胞仪对诱导扩增的SPCs进行分析鉴定并分选纯化。间接免疫荧光染色法观察SPCs培养到第28天后人平滑肌细胞特异性肌动蛋白（a-SMA）的表达情况。收集培养第12天的SPCs,随机（补充具体的随机方法？）分为5组并给予不同浓度葡萄糖干预：对照组（5．5mmol／L）,11 mmol／L组,22mmol／L组,44mmol／L组和渗透压对照组（5．5mmol／L葡萄糖加38mmol／L甘露醇）。分别用噻唑蓝（methyl thiazolyl tetrazolium,MTY）比色法．Transwell小室迁移实验以及黏附能力测定实验检测各组干预6d后SPCs增殖、迁移和黏附能力的变化。此外,培养SPCs8d,期间用22mmol／L葡萄糖分别干预0、2、4、8、d,观察各组细胞增殖、迁移和黏附能力的变化。结果与对照组相比,高糖各组均能明显促进外周血SPCs的增殖、迁移和黏附能力,其中22mmol／L葡萄糖组的影响最为显著,44mmol／L葡萄糖组的促进作用有所下降。用22mmol／L葡萄糖分别干预SPCs0、2、4、8d,其增殖、迁移和黏附能力随着作用时间延长而增强,以干预8d组最显著。结论高糖能在一定范围内增强外周血SPCs的增殖、迁移、黏附能力,随着浓度增加和时间延长,作用更明显。推测长期高血糖通过促进SPCs的功能参与受损血管过度修复．引起部分心血管疾病的发生发展。     

成年鼠骨髓单个核细胞在体外培养中分化为平滑肌祖细胞

目的:探讨大鼠骨髓单个核细胞在体外经条件培养基诱导定向分化成平滑肌祖细胞的可行性。方法:分离4～6周龄的大鼠胫骨、股骨,以4℃预冷的DMEM培养基冲出骨髓,密度梯度离心法分离骨髓单个核细胞,在血小板源生长因子-BB(PDGF-BB)和碱性成纤维细胞生长因子(b-FGF)作用下,培养8～12d形成贴壁的梭形细胞。采用CD34与α-SMA免疫荧光染色进行鉴定,RT-PCR法测定其α-SMAmRNA表达情况。结果:在PDGF-BB作用下,82%的骨髓单个核细胞α-SMA染色阳性,78%细胞CD34染色阳性,新鲜分离的骨髓单个核细胞不表达α-SMAmRNA,体外培养后表达α-SMAmRNA。结论:体外培养的骨髓单个核细胞能分化为平滑肌祖细胞,可作为研究平滑肌细胞分化和筛选抑制再狭窄药物的工具。     

Contractile smooth muscle cells derived from hair-follicle stem cells

AIMS: We hypothesized that hair-follicle stem cells can differentiate toward smooth contractile muscle cells, providing an autologous cell source for cardiovascular tissue regeneration. METHODS AND RESULTS: Smooth muscle progenitor cells (SMPCs) were obtained from ovine hair follicles using a tissue-specific promoter and fluorescence-activated cell sorting. Hair-follicle smooth muscle progenitor cells (HF-SMPCs) expressed several markers of vascular smooth muscle including alpha-actin, calponin, myosin heavy chain (MHC), caldesmon, smoothelin, and SM22. HF-SMPCs were highly proliferative and showed high clonogenic potential without any signs of chromosomal abnormalities as evidenced by karyotype analysis. HF-SMPCs compacted fibrin hydrogels to a similar extent as vascular smooth muscle cells from ovine umbilical veins (V-SMCs), indicating the development of the force-generating machinery. In addition, cylindrical tissue equivalents prepared with HF-SMPCs displayed significant contractility in response to vasoactive agonists including KCl and the thromboxane A2 mimetic U46619, suggesting that these cells had developed receptor and non-receptor-mediated pathways of contractility. Finally, transforming growth factor-beta1 promoted differentiation of HF-SMPCs toward a mature SMC phenotype as suggested by increased expression of MHC and enhanced matrix compaction. CONCLUSION: Our results suggest that hair follicles may be an easily accessible, autologous, and rich source of functional SMPC for cardiovascular tissue engineering and regenerative medicine.     

Vascular smooth muscle cells differ from other smooth muscle cells: predominance of vimentin filaments and a specific alpha-type actin.

Smooth muscle cells of the digestive, respiratory, and urogenital tracts contain desmin as their major, if not exclusive, intermediate-size filament constituent and also show a predominance of gamma-type smooth muscle actin. We have now examined smooth muscle tissue of different blood vessels (e.g., aorta, small arteries, arterioles, venules, and vena cava) from various mammals (man, cow, pig, rabbit, rat) by one- and two-dimensional gel electrophoresis of cell proteins and by immunofluorescence microscopy using antibodies to different intermediate-sized filament proteins. Intermediate-sized filaments of vascular smooth muscle cells contain abundant amounts of vimentin and little, if any, desmin. On gel electrophoresis, vascular smooth muscle vimentin appears as two isoelectric variants of apparent pI values of 5.30 and 5.29, shows the characteristic series of proteolytic fragments, and is one of the major cell proteins. Thus vimentin has been demonstrated in a smooth muscle cell present in the body. Vascular smooth muscle cells are also distinguished by the predominance of a smooth muscle-specific alpha-type actin, whereas gamma-type smooth muscle actin is present only as a minor component. It is proposed that the intermediate filament and actin composition of vascular smooth muscle cells reflects a differentiation pathway separate from that of other smooth muscle cells and may be related to special functions and pathological disorders of blood vessels.     

Origin of vascular smooth muscle cells and the role of circulating stem cells in transplant arteriosclerosis

To date, clinical solid-organ transplantation has not achieved its goals as a long-term treatment for patients with end-stage organ failure. Development of so-called chronic transplant dysfunction (CTD) is now recognized as the predominant cause of allograft loss long term (after the first postoperative year) after transplantation. CTD has the remarkable histological feature that the luminal areas of intragraft arteries become obliterated, predominantly with vascular smooth muscle cells (VSMCs) intermingled with some inflammatory cells (transplant arteriosclerosis, or TA). The development of TA is a multifactorial process, and many risk factors have been identified. However, the precise pathogenetic mechanisms leading to TA are largely unknown and, as a result, adequate prevention and treatment protocols are still lacking. This review discusses the origin (donor versus recipient, bone marrow versus nonbone marrow) of the VSMCs in TA lesions. Poorly controlled influx and subsequent proliferative behavior of these VSMCs are considered to be critical elements in the development of TA. Available data show heterogeneity when analyzing the origin of neointimal VSMCs in various transplant models and species, indicating the existence of multiple sites of origin. Based on these findings, a model considering plasticity of VSMC origin in TA in relation to severity and extent of graft damage is proposed.     

Coadministration of endothelial and smooth muscle progenitor cells enhances the efficiency of proangiogenic cell-based therapy

Cell-based therapy is a promising approach designed to enhance neovascularization and function of ischemic tissues. Interaction between endothelial and smooth muscle cells regulates vessels development and remodeling and is required for the formation of a mature and functional vascular network. Therefore, we assessed whether coadministration of endothelial progenitor cells (EPCs) and smooth muscle progenitor cells (SMPCs) can increase the efficiency of cell therapy. Unilateral hindlimb ischemia was surgically induced in athymic nude mice treated with or without intravenous injection of EPCs (0.5 x 10(6)), SMPCs (0.5 x 10(6)) and EPCs+SMPCs (0.25 x 10(6)+0.25 x 10(6)). Vessel density and foot perfusion were increased in mice treated with EPCs+SMPCs compared to animals receiving EPCs alone or SMPCs alone (P<0.001). In addition, capillary and arteriolar densities were enhanced in EPC+SMPC-treated mice compared to SMPC and EPC groups (P<0.01). We next examined the role of Ang-1/Tie2 signaling in the beneficial effect of EPC and SMPC coadministration. Small interfering RNA directed against Ang-1-producing SMPCs or Tie2-expressing EPCs blocked vascular network formation in Matrigel coculture assays, reduced the rate of incorporated EPCs within vascular structure, and abrogated the efficiency of cell therapy. Production of Ang-1 by SMPCs activates Tie2-expressing EPCs, resulting in increase of EPC survival and formation of a stable vascular network. Subsequently, the efficiency of EPC- and SMPC-based cotherapy is markedly increased. Therefore, coadministration of different types of vascular progenitor cells may constitute a novel therapeutic strategy for improving the treatment of ischemic diseases.