李強(qiáng) 張林霞 張愛君 陶常波 李雪陽(yáng) 馬志兵 金培生
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SDF-1-CXCR4/CXCR7信號(hào)對(duì)脂肪干細(xì)胞促血管新生能力的影響
李強(qiáng)張林霞張愛君陶常波李雪陽(yáng)馬志兵金培生
【摘要】目的研究SDF-1對(duì)ADSCs體外促血管新生能力的影響,并探討CXCR4、CXCR7在其中的作用。方法體外培養(yǎng)ADSCs,檢測(cè)其CXCR4、CXCR7的表達(dá);SDF-1刺激ADSCs,并分別加入CXCR4、CXCR7封閉抗體,檢測(cè)ADSCs-CM中VEGF、HGF、β-FGF含量,及其對(duì)hUVECs微血管形成的影響。結(jié)果成功培養(yǎng)ADSCs;ADSCs體外培養(yǎng)傳代過程中CXCR4、CXCR7表達(dá)持續(xù)下降;SDF-1刺激上調(diào)CXCR4、CXCR7表達(dá),并提高ADSCs對(duì)血管活性因子的分泌,及促進(jìn)hUVEC微血管的形成;封閉CXCR4、CXCR7均可顯著抑制SDF-1的促進(jìn)作用。結(jié)論體外環(huán)境下,SDF-1可上調(diào)ADSCs中CXCR4、CXCR7表達(dá),并通過SDF-1-CXCR4/CXCR7兩條通路提高ADSCs的促血管新生能力。
【關(guān)鍵詞】脂肪干細(xì)胞基質(zhì)細(xì)胞衍生因子-1血管新生
脂肪干細(xì)胞(Adipose-derived stem cells,ADSCs)是來自脂肪組織基質(zhì)的成體干細(xì)胞,含量豐富,獲取及培養(yǎng)方法簡(jiǎn)單,可向脂肪、骨、軟骨、神經(jīng)等多個(gè)細(xì)胞系分化[1];且具有血管內(nèi)皮細(xì)胞分化潛能[2],可分泌多種因子促進(jìn)血管新生(Angiogenesis)及組織修復(fù)[3],在再生醫(yī)學(xué)及組織工程領(lǐng)域應(yīng)用廣泛[4]。
基質(zhì)細(xì)胞衍生因子-1(Stromal cell-derived factor -1,SDF-1)是重要的細(xì)胞趨化因子,通過受體CXCR4、CXCR7可動(dòng)員多種細(xì)胞參與血管新生[5]。我們前期研究證實(shí),ADSCs可分泌SDF-1,促進(jìn)HUVEC形成微血管[6]。有報(bào)道認(rèn)為,SDF-1可作為旁分泌因子作用于ADSCs本身,提高其活性[7-8]。SDF-1對(duì)ADSCs的分泌及促血管新生能力影響的研究尚未見報(bào)道。本實(shí)驗(yàn)旨在探討SDF-1及其受體CXCR4、CXCR7 對(duì)ADSCs促血管新生能力的影響,為增強(qiáng)ADSCs在組織工程產(chǎn)品血管化,及缺血性疾病干細(xì)胞治療方面的作用,提供新的理論依據(jù)。
人臍靜脈內(nèi)皮細(xì)胞(human umbilical vein endothelial cells,hUVECs)購(gòu)自中國(guó)醫(yī)學(xué)科學(xué)院。
胎牛血清+L-DMEM(Gibco,美國(guó));PE-鼠抗人CD29(Serotec,英國(guó));PE-鼠抗人CD106(BD,美國(guó));FITC-鼠抗人CD34(Miltenyi Biotee,德國(guó));FITC-鼠抗人CD44、CD49d、CD80(Serotec,英國(guó));兔抗人CXCR4、CXCR7、β-actin(Cell Signaling Technology,美國(guó));Matrigel TM4凝膠(BD Biosciences,美國(guó));RPMI-1640(Gibco,美國(guó));ELISA試劑盒(R&D,美國(guó))。
2.1ADSCs獲取、培養(yǎng)及鑒定
選取3例30~45歲健康女性腹部吸脂患者,經(jīng)醫(yī)院倫理委員會(huì)批準(zhǔn),患者知情同意。以酶消化法獲取原代ADSCs,10%胎牛血清+L-DMEM 37℃、5% CO2孵育,0.2%胰酶消化傳代[6,10]。
細(xì)胞表面標(biāo)記物檢測(cè):第3代ADSCs 1×105個(gè),流式細(xì)胞儀檢測(cè)細(xì)胞表面標(biāo)志物,按常規(guī)進(jìn)行。一抗為PE-鼠抗人CD29、CD106單克隆抗體,F(xiàn)ITC-鼠抗人CD34、CD44、CD49d、CD80單克隆抗體。
細(xì)胞分化能力檢測(cè):98 mL DMEM+10%FBS+ 100 μL β-磷酸甘油+1 mL地塞米松+1 mL Vit-C誘導(dǎo)28 d,茜素紅鈣結(jié)節(jié)染色檢測(cè)成骨分化能力。DMEM+10%FBS+25 μg/L EGF+5 μg/L ATRA+5 μg/L FGF+5 μg/L胰島素+0.4 μg/mL氫化可的松+20 mg/L谷氨酰胺誘導(dǎo)8 d,細(xì)胞角蛋白免疫組化染色檢測(cè)成表皮分化能力。
2.2CXCR4、CXCR7表達(dá)水平檢測(cè)
Western blot:原代至第3代ADSCs各1×106個(gè),細(xì)胞裂解后提取總蛋白。25 μL上樣,120 g/L SDSPAGE凝膠電泳并轉(zhuǎn)移至PVDF膜,Western blot檢測(cè),一抗為兔抗人CXCR4、CXCR7、β-actin單克隆抗體,二抗為辣根過氧化物酶標(biāo)記羊抗兔IgG,生物素-親和素標(biāo)記系統(tǒng)檢測(cè)。照相后ImgaeJ軟件分析條帶灰度值。
流式細(xì)胞計(jì)數(shù):原代至第3代ADSCs 1×105個(gè),流式細(xì)胞儀檢測(cè)CXCR4、CXCR7表達(dá),方法同上。
2.3SDF-1刺激對(duì)CXCR4、CXCR7表達(dá)影響
3)新型擴(kuò)孔鉆頭的綜合性能有明顯的提高,擴(kuò)孔后其井徑均大于170 mm,定向鉆井造斜率達(dá)到9.9°/30 m,鉆頭平均進(jìn)尺達(dá)到93 m,機(jī)械鉆速為1.24 m/h,與國(guó)外同類鉆頭相比,進(jìn)尺提高50%,機(jī)械鉆速提高4%。
取處于對(duì)數(shù)生長(zhǎng)期的第3代ADSCs,LDMEM+1%胎牛血清+0.5 mg/L SDF-1培養(yǎng)2 d,Western blot、流式細(xì)胞計(jì)數(shù)檢測(cè)CXCR4、CXCR7表達(dá)水平。
2.4SDF-1-CXCR4/CXCR7對(duì)ADSCs分泌功能的影響
第4代ADSCs接種于6孔板,常規(guī)培養(yǎng)至細(xì)胞70%融合。實(shí)驗(yàn)分5組:SDF-1刺激組,以LDMEM+1%胎牛血清+0.5 mg/L SDF-1培養(yǎng);CXCR4封閉組、CXCR7封閉組,先以10 mg/L CXCR4或CXCR7抗體封閉2 h,再加入SDF-1;CXCR4、CXCR7封閉組,同時(shí)加入兩種抗體;對(duì)照組L-DMEM+ 1%胎牛血清培養(yǎng)。2 d后收集條件培養(yǎng)基(ADSCs-CM),離心后取上清,過濾、分裝備用。各取200 μL ADSCs-CM,ELISA法檢測(cè)VEGF、HGF、β-FGF含量,步驟按說明書進(jìn)行。
2.5SDF-1-CXCR4/CXCR7對(duì)ADSCs促hUVEC微血管形成的影響
48孔板,每孔100μL冷MatrigelTM4凝膠,37℃、5%CO230 min。hUVECs每孔2×104個(gè)接種于48孔板。分別加入各組ADSCs-CM 75 μL及RPMI-1640+1%胎牛血清25 μL。12 h后取下室細(xì)胞,多聚甲醛固定,鏡下觀察。Weidner法[9]計(jì)數(shù)管樣毛細(xì)血管數(shù)量及密度,選微管密度最高的5個(gè)視野,200倍鏡下觀察計(jì)數(shù),以對(duì)照組為基點(diǎn)(100%)。
2.6數(shù)據(jù)統(tǒng)計(jì)分析
所有實(shí)驗(yàn)重復(fù)3次。以SPSS 16.0行統(tǒng)計(jì)學(xué)分析,數(shù)據(jù)用(x±s)表示,組間比較采用t檢驗(yàn),P<0.05為差異有統(tǒng)計(jì)學(xué)意義。
3.1ADSCs培養(yǎng)與鑒定
經(jīng)體外培養(yǎng)后獲取可連續(xù)傳代的細(xì)胞群體,呈類似成纖維細(xì)胞的長(zhǎng)梭形;流式細(xì)胞檢測(cè)證實(shí),細(xì)胞表面CD34、CD80、CD106陰性,CD29、CD44、CD49d陽(yáng)性;成骨誘導(dǎo)28 d后,茜素紅染色可見散在紅色結(jié)節(jié);成表皮誘導(dǎo)8 d后,部分細(xì)胞變?yōu)閳A形或不規(guī)則形,呈鋪路石樣排列,部分細(xì)胞角蛋白陽(yáng)性表達(dá)(圖1)。
圖1 ADSCs體外培養(yǎng)與鑒定Fig.1Culture and identification of ADSCs in vitro
3.2ADSCs表面CXCR4、CXCR7表達(dá)變化
流式細(xì)胞計(jì)數(shù)發(fā)現(xiàn),CXCR4、CXCR7表達(dá)水平隨體外傳代次數(shù)增加而逐漸降低(CXCR4、CXCR7陽(yáng)性率原代為51.4%和80.3%;第1代為23.27%和19.44%;第2代為5.35%和3%;第3代為2.54%和1.89%);SDF-1刺激可上調(diào)CXCR4、CXCR7的表達(dá)(CXCR4、CXCR7陽(yáng)性率分別為35.11%和27.6%);Western blot免疫印跡檢測(cè)并用ImgaeJ軟件分析條帶灰度,結(jié)果與流式細(xì)胞計(jì)數(shù)一致(圖2)。
圖2 ADSCs表面CXCR4、CXCR7的表達(dá)Fig.2CXCR4 and CXCR7 expression in ADSCs
Western blot及流式細(xì)胞檢測(cè)均證實(shí),原代ADSCs表面CXCR4、CXCR7呈陽(yáng)性表達(dá),傳代后兩者的表達(dá)迅速降低,至第3代時(shí)均為陰性。0.5 mg/L SDF-1刺激2 d后,CXCR4和CXCR7的表達(dá)均顯著提高。
3.3SDF-1-CXCR4/CXCR7對(duì)ADSCs分泌功能的影響
各組ADSCs-CM中均檢測(cè)到VEGF、HGF和β-FGF。SDF-1刺激組中三者含量均顯著上升,CXCR4、CXCR7抗體封閉組較SDF-1刺激組有所降低,同時(shí)封閉兩者后降至對(duì)照組水平(圖3)。
圖3 ADSCs分泌功能檢測(cè)Fig.3The secretion of VEGF,HGF and β-FGF from ADSCs performed by ELISA
由此可見,SDF-1能促進(jìn)ADSCs對(duì)VEGF、HGF 和β-FGF分泌,CXCR4、CXCR7抗體封閉能部分逆轉(zhuǎn)該促進(jìn)作用,同時(shí)使用兩種抗體則可抵消SDF-1的促進(jìn)作用。
3.4SDF-1-CXCR4/CXCR7對(duì)ADSCs促hUVECs微血管形成的影響
SDF-1刺激組hUVECs毛細(xì)血管形成的數(shù)量及管狀結(jié)構(gòu)完整性較對(duì)照組高,CXCR4、CXCR7阻斷組中血管數(shù)量較SDF-1刺激組有所降低,同時(shí)阻斷組小管形成能力降至對(duì)照組水平(圖4)。
圖4 ADSCs促HUVECs小管形成作用Fig.4 ADSCs promote tube formation of hUVECs
近年來,間充質(zhì)干細(xì)胞(MSCs)在組織工程及再生醫(yī)學(xué)領(lǐng)域應(yīng)用極為廣泛。組織工程植入物的存活及抗感染能力的獲得,很大程度上取決于血運(yùn)恢復(fù)情況[10],損傷組織的修復(fù)更是依賴于干細(xì)胞所分泌的血管活性因子的作用[11]。因此,用于構(gòu)建組織工程產(chǎn)品及干細(xì)胞治療的種子細(xì)胞需具有一定的促血管新生能力。ADSCs是新發(fā)現(xiàn)的MSCs,不僅能分化為血管內(nèi)皮及平滑肌細(xì)胞,直接參與血管重建[2],還可分泌大量活性因子促進(jìn)血管新生[3]。我們的前期研究和本實(shí)驗(yàn)均證實(shí)ADSCs可分泌VEGF、HGF、β-FGF等,有利于血管新生和組織修復(fù)[6]。
ADSCs要發(fā)揮作用必需移植到受損組織中,此時(shí)將面對(duì)缺氧、氧化應(yīng)激及炎癥等不利環(huán)境,常導(dǎo)致細(xì)胞的活性降低及死亡,嚴(yán)重影響療效[12],需對(duì)ADSCs進(jìn)行一定干預(yù),以增強(qiáng)細(xì)胞活性,提高其修復(fù)能力。低氧誘導(dǎo)[13]、基因修飾[14]均被證實(shí)可一定程度提高ADSCs促血管新生能力。但基因修飾的安全性及穩(wěn)定性仍存疑,低氧誘導(dǎo)可能會(huì)降低干細(xì)胞分化能力。因此需探尋新的簡(jiǎn)單有效的ADSCs預(yù)處理方案。
1993年,Tashiro等[15]首次發(fā)現(xiàn)趨化因子SDF-1,并克隆出其蛋白結(jié)構(gòu)。SDF-1與其受體CXCR4、CXCR7結(jié)合,可動(dòng)員造血干細(xì)胞、內(nèi)皮祖細(xì)胞和RBCCs(Recruited bone marrow-derived circulating cells)等參與血管新生,是重要的血管重建通路[5]。對(duì)MSCs同樣具有較強(qiáng)的動(dòng)員、趨化作用。Liu等[16]證實(shí),SDF-1可增強(qiáng)BMSCs增殖、分泌功能,促進(jìn)腎缺血再灌注損傷修復(fù)。Kim等[7]證實(shí)SDF-1可動(dòng)員并活化ADSCs,促進(jìn)創(chuàng)面愈合。但SDF-1對(duì)ADSCs分泌及促血管新生能力的影響尚未見報(bào)道。我們用SDF-1處理ADSCs,發(fā)現(xiàn)其分泌及促hUVEC小管形成能力均顯著增強(qiáng)。SDF-1可刺激ADSCs分泌血管活性因子,從而促進(jìn)hUVECs微血管形成,提示在局部移植或靜脈輸入ADSCs之前,以一定濃度的SDF-1預(yù)處理,可增強(qiáng)細(xì)胞促血管新生能力,以求更好的療效。
SDF-1的兩個(gè)受體CXCR4和CXCR7所介導(dǎo)的生物學(xué)效應(yīng)不盡相同。SDF-1/CXCR4軸的激活能促進(jìn)BMSCs趨化遷移,CXCR7則更多與BMSCs增殖能力相關(guān)[16]。為研究?jī)烧咴贏DSCs中的作用,我們首先檢測(cè)了CXCR4、CXCR7在ADSCs中的表達(dá)情況,發(fā)現(xiàn)兩者在原代ADSCs中陽(yáng)性表達(dá),但隨著體外培養(yǎng)傳代次數(shù)的增加,其表達(dá)呈快速下降,至第3代則為陰性。其原因可能為:①胰蛋白酶消化時(shí)破壞了細(xì)胞表面蛋白;②體外培養(yǎng)環(huán)境與體內(nèi)有所差異,尤其是氧分壓不同,影響受體的表達(dá)。體外培養(yǎng)的ADSCs中CXCR4和CXCR7水平過低,可能會(huì)影響其在體內(nèi)的歸巢及修復(fù)能力,用脂質(zhì)體[17]或慢病毒[18]對(duì)其進(jìn)行基因修飾,可維持較高的受體水平,低氧誘導(dǎo)也是可行的方案。本實(shí)驗(yàn)中,我們發(fā)現(xiàn)SDF-1刺激同樣可提高CXCR4和CXCR7的表達(dá)。SDF-1可誘導(dǎo)其受體表達(dá),這種正反饋效應(yīng)與其他細(xì)胞因子(如VEGF等)相似,提示SDF-1刺激ADSCs可提高CXCR4和CXCR7的表達(dá),提高細(xì)胞遷移歸巢能力。
我們進(jìn)一步用CXCR4和CXCR7的中和抗體,分別封閉兩條通路,發(fā)現(xiàn)阻斷CXCR4、CXCR7均能不同程度的抑制SDF-1所引發(fā)的ADSCs分泌及促微血管形成能力的提高,同時(shí)阻斷兩者后ADSCs促血管新生能力降至正常??梢奡DF-1-CXCR4/CXCR7軸在ADSCs的分泌及促微血管形成中具有重要作用。
綜上,本研究證實(shí),體外環(huán)境下SDF-1刺激可上調(diào)ADSCs中CXCR4和CXCR7的表達(dá),并能提高ADSCs對(duì)血管活性因子的分泌,以及對(duì)hUVECs小管形成的促進(jìn),該效應(yīng)是通過SDF-1-CXCR4/CXCR7兩條通路共同完成的。
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The Influence of Stromal Cell-derived Factor-1 Promoting Angiogenesis of Adipose-derived Stem Cells via CXCR4 and CXCR7 Pathway in vitro
LI Qiang1,2,ZHANG Linxia1,ZHANG Aijun1,TAO Changbo1,LI Xueyang1,MA Zhibing1,
JIN Peisheng1.1 Plastic Surgery Department,Xuzhou Medical College Affiliated Hospital,Xuzhou 221000,China;2 Plastic Surgery Hospital,Peking Union Medical College&Chinese Academy of Medical Sciences,Beijing 100144,China. Corresponding author:JIN Peisheng(E-mail:jinps2006@163.com).
【Abstract】ObjectiveTo investigate the role of SDF-1 in promoting ADSCs angiogenesis,as well as CXCR4,CXCR7. MethodsADSCs were primary cultured by enzyme digestion method.Flow cytomertry and western blot assays were performed to detect the expression of CXCR4,CXCR7.ADSCs were treated with SDF-1 and neutralizing anti-CXCR4 and/or anti-CXCR7 antibody.ELISA was used to detect the secretion of VEGF,HGF,and β-FGF.hUVECs tube formation assay was used to examine the effect of SDF-1 and neutralizing antibody CXCR4,CXCR7 on promoting angiogenesis property of ADSCs.ResultsADSCs were successfully isolated and cultured from human liposuction tissue.CXCR4 and CXCR7 expression were significantly decreased during cell culture.When treated with SDF-1,CXCR4 and CXCR7 expression were significantly increased.In addition,SDF-1 pretreating also promoted the secretion of angiogenesis factors VEGF,HGF,β-FGF and increased the ability of tube formation of hUVECs induced by ADSCs.The blocking of CXCR4 and CXCR7 activation also inhibited the promotion of angiogenesis property of ADSCs caused by SDF-1.ConclusionSDF-1 pretreating can up-regulate the expression of CXCR4 and CXCR7 in ADSCs.Furthermore,it also promotes the angiogenesis ability of ADSCs through CXCR4 and CXCR7 pathways.
【Key words】Adipose-derived stem cells;Stromal cell-derived factor-1;Angiogenesis
收稿日期:(2015年11月4日;修回日期:2015年12月12日)
通信作者:金培生(E-mail:jinps2006@163.com)。
doi:10.3969/j.issn.1673-0364.2016.01.002
【中圖分類號(hào)】Q813.1+1
【文獻(xiàn)標(biāo)識(shí)碼】A
【文章編號(hào)】1673-0364(2016)01-0006-05
作者單位:221000江蘇省徐州市徐州醫(yī)學(xué)院附屬醫(yī)院整形外科(李強(qiáng),張林霞,張愛君,陶常波,李雪陽(yáng),馬志兵,金培生);100144北京市中國(guó)醫(yī)學(xué)科學(xué)院整形外科醫(yī)院(李強(qiáng))。