王子婧,錢智勇,郭希民,高德偉
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血小板衍生生長因子?C對體外培養(yǎng)血管內(nèi)皮細(xì)胞及間充質(zhì)干細(xì)胞的影響
王子婧,錢智勇,郭希民,高德偉*
(解放軍總醫(yī)院南樓臨床部綜合外二科,北京 100853)
觀察血小板衍生生長因子?C(PDGF-C)對體外培養(yǎng)的血管內(nèi)皮細(xì)胞(VECs)及間充質(zhì)干細(xì)胞(MSCs)的影響。采用培養(yǎng)的大鼠主動脈內(nèi)皮細(xì)胞和MSCs,應(yīng)用細(xì)胞直接計(jì)數(shù)法、噻唑藍(lán)比色法(MTT法)評價(jià)細(xì)胞的增殖情況,流式細(xì)胞術(shù)檢測細(xì)胞周期,利用Transwell細(xì)胞遷移實(shí)驗(yàn)和細(xì)胞劃痕實(shí)驗(yàn)測定細(xì)胞遷移能力。PDGF-C能明顯刺激VECs和MSCs的增殖,增加兩種細(xì)胞S期細(xì)胞的比例,對VECs增殖呈劑量依賴關(guān)系,對MSCs的促增殖作用在20μg/L達(dá)高峰。同時(shí),PDGF-C促進(jìn)VECs和MSCs的遷移能力,對MSCs遷移作用強(qiáng)于VECs。PDGF-C可促進(jìn)培養(yǎng)的VECs、MSCs的增殖與遷移能力。
大鼠;血小板衍生生長因子C;血管內(nèi)皮細(xì)胞;間充質(zhì)干細(xì)胞;細(xì)胞增殖;遷移
血管內(nèi)皮細(xì)胞(vascular endothelial cells,VECs)是血管內(nèi)循環(huán)血液與中層平滑肌細(xì)胞之間的機(jī)械屏障,維持機(jī)體重要的生理功能。內(nèi)皮細(xì)胞損傷后脫落,膠原及組織因子暴露,是形成動靜脈血栓的重要始動因素。因此,血管內(nèi)皮損傷后修復(fù)可作為血栓性疾病治療的方法之一。其修復(fù)原理主要包括兩方面:一是增強(qiáng)成熟內(nèi)皮細(xì)胞的增殖和分化能力,加速內(nèi)皮的自身修復(fù);二是動員間充質(zhì)干細(xì)胞(mesenchymal stem cells,MSCs)歸巢到損傷部位,內(nèi)皮化后替代修復(fù)[1]。血小板衍生生長因子(platelet derived growth factor,PDGF)是正常組織生長和維持的重要生長因子,包括至少PDGF-A,B,C,D 4個(gè)成員,其中PDGF-A和B的研究已較成熟,而PDGF-C則是新發(fā)現(xiàn)成員之一。研究表明PDGF-C有較強(qiáng)的促進(jìn)血管新生能力[2.3],其所具有的多重生物學(xué)效應(yīng)是血管內(nèi)皮生長因子(vascular endothelial growth factor,VEGF)和堿性成纖維細(xì)胞生長因子(basic fibroblast growth factor,bFGF)等其他生長因子所不具備的獨(dú)特功能[4]。且PDGF-C參與了動脈損傷后修復(fù)的過程,機(jī)制是促血管平滑肌細(xì)胞凋亡或干預(yù)血管平滑肌細(xì)胞遷移[5],而對內(nèi)皮細(xì)胞和干細(xì)胞的作用尚沒有明確涉及。為此,我們利用PDGF-C對體外培養(yǎng)的主動脈內(nèi)皮細(xì)胞和骨髓MSCs進(jìn)行刺激,測定細(xì)胞增殖情況,評價(jià)細(xì)胞的遷移能力,從而了解PDGF-C對VECs及MSCs的影響。
PDGF-C(美國Peprotech公司);DMEM細(xì)胞培養(yǎng)液(美國Gibco公司);胎牛血清(fatal bovine serum,F(xiàn)BS);流式細(xì)胞周期檢測試劑盒、Hoechst33258染色試劑盒(碧云天生物技術(shù)研究所);噻唑藍(lán)(美國Sigma公司)。
超凈工作臺(蘇州市凈化設(shè)備公司YJ-875);二氧化碳培養(yǎng)箱(美國Shell-Lab2323型);倒置相差熒光顯微鏡(日本Nikon公司);流式細(xì)胞儀(美國Elite SP型);酶標(biāo)分析儀(美國Bio-RAD Model 550型)、細(xì)胞計(jì)數(shù)儀(美國FJ-2003型)。
VECs的原代培養(yǎng)和體外增殖:過量1g/L戊巴比妥鈉注入SD大鼠(150g)的腹腔內(nèi),麻醉致死,75%乙醇浸泡消毒3min后移入超凈臺,無菌條件下打開胸腔暴露胸主動脈,快速取胸主動脈。用眼科鑷夾除動脈外周的結(jié)締組織及脂肪,磷酸鹽緩沖液(phosphate buffer solution,PBS)沖洗管腔內(nèi)面殘留血液。眼科剪剪開血管腔,將血管剪成2mm×2mm大小均勻的組織塊后轉(zhuǎn)移到25ml的培養(yǎng)瓶中,在含10% FBS的DMEM中培養(yǎng),待內(nèi)皮細(xì)胞長成典型的鋪路石樣、細(xì)胞融合達(dá)到80%~90%,經(jīng)胰酶消化后傳代、取第5~8代細(xì)胞用作實(shí)驗(yàn),因子Ⅷ免疫熒光鑒定VECs。將存有MSCs(軍事醫(yī)學(xué)科學(xué)院提供)的凍存管從液氮中取出,37℃水浴復(fù)蘇,用含10% FBS的α-MEM培養(yǎng)液常規(guī)培養(yǎng)。
分別取第5代對數(shù)生長期的VECs和MSCs,消化離心后計(jì)數(shù),以2×104個(gè)/ml密度接種于96孔培養(yǎng)板,常規(guī)培養(yǎng)24h后換用2%FBS繼續(xù)培養(yǎng)24h后,分別加入不同濃度的PDGF-C(10,20,30,40,50μg/L),設(shè)對照組,加入等體積PBS。每組設(shè)5個(gè)復(fù)孔,培養(yǎng)24h后加入MTT溶液(5g/L)20μl,繼續(xù)孵育4h后棄培養(yǎng)基,每孔加入150μl二甲基亞砜(dimethyl sulfoxide,DMSO),吹勻后492nm波長處測吸光度值(492nm),以時(shí)間為橫軸,吸光度為縱軸繪制細(xì)胞生長曲線。
取VECs和MSCs,常規(guī)培養(yǎng)24h,換含2%FBS的培養(yǎng)基及培養(yǎng)24h后,加入PDGF-C(20μg/L),對照組加入等量的PBS,再孵育24h后,胰酶消化3min,輕輕吹打呈細(xì)胞懸液,800r/min離心后,PBS漂洗3遍,重復(fù)離心,加入1ml PBS重懸細(xì)胞調(diào)整細(xì)胞密度至1.5×106/ml,過300目細(xì)胞篩,去除團(tuán)聚細(xì)胞,加入-20℃預(yù)冷的70%乙醇溶液,4℃過夜。PBS充分漂洗離心后加入10μl RNA酶,37℃水浴30min,后加入25μl碘化丙啶染色,避光30min放于4℃冰箱,上樣前輕彈試管,流式細(xì)胞儀檢測細(xì)胞周期(激發(fā)波長488nm)。
將兩種細(xì)胞以2×105/ml的密度接種在6孔培養(yǎng)板中常規(guī)培養(yǎng)后,換用含2%FBS細(xì)胞培養(yǎng)基培養(yǎng),細(xì)胞融合達(dá)到80%后,用20μl無菌槍頭在每孔勻速縱向劃一道劃痕,用PBS輕輕沖洗細(xì)胞,加入含濃度為20μg/L的PDGF-C培養(yǎng)基,對照組加入等體積PBS。于0,6,12,24h進(jìn)行細(xì)胞拍照取材,觀察各組細(xì)胞向空白處遷移的情況。
用50mg/L Matrigel稀釋8倍后滴加于Transwell小室底部膜的下室面,在超凈臺內(nèi)風(fēng)干后備用。取第5代對數(shù)期細(xì)胞消化離心后,PBS洗1~2遍,用含10g/L牛血清白蛋白的培養(yǎng)基重懸細(xì)胞,調(diào)整細(xì)胞密度為2×105/ml。在Transwell小室內(nèi)加200μl細(xì)胞懸液,下室加入500μl含20μg/L PDGF-C的培養(yǎng)基,對照組加入等體積PBS。于二氧化碳培養(yǎng)箱中培養(yǎng)24h后,用4%多聚甲醛液4℃固定15min,PBS充分清洗2遍,每次3min。分別加入Hoechst33258染色液,室溫靜置30min,充分染色后PBS清洗,熒光倒置顯微鏡下觀察并拍照取材。
原代培養(yǎng)VECs 4d時(shí),顯微鏡下可見有少量的細(xì)胞遷出貼壁生長,細(xì)胞呈短梭形或多角形。培養(yǎng)至12d,細(xì)胞貼壁生長達(dá)到培養(yǎng)瓶面積>2/3,呈現(xiàn)內(nèi)皮細(xì)胞典型的“鋪路石”樣特征。取第4代生長良好的VECs,經(jīng)因子Ⅷ抗體進(jìn)行細(xì)胞免疫熒光化學(xué)染色鑒定,呈陽性表現(xiàn);復(fù)蘇后的MSCs融合單層,細(xì)胞形態(tài)大多呈長梭形或多角形,符合MSCs的細(xì)胞形態(tài)(圖1)。
觀察不同濃度下PDGF-C對VECs和MSCs增殖的影響。結(jié)果顯示,與對照組相比,加入PDGF-C的實(shí)驗(yàn)組細(xì)胞增殖能力明顯增強(qiáng),且差異有統(tǒng)計(jì)學(xué)意義(<0.05)。加入PDGF-C后,兩種細(xì)胞均在第4天增殖達(dá)高峰。隨著PDGF-C濃度的增加,VECs的增殖能力逐漸增強(qiáng),呈現(xiàn)出一種濃度效應(yīng)關(guān)系(圖2);而MSCs的增殖在PDGF-C為20μg/L濃度時(shí)達(dá)高峰(<0.01;圖3),當(dāng)濃度繼續(xù)增加時(shí),MSCs的增殖能力不再繼續(xù)增強(qiáng)。
圖1 血管內(nèi)皮細(xì)胞與間充質(zhì)干細(xì)胞的細(xì)胞培養(yǎng)及鑒定
Figure 1 Cultivation and identification of VECs and MSCs
VECs: vascular endothelial cells; MSCs: mesenchymal stem cells; A: primary VECs (×100); B: cultured MSCs (×100); C: VECs Dapi nuclear staining (×400); D: positive expression of factor Ⅷ in VECs (×400)
實(shí)驗(yàn)結(jié)果表明,經(jīng)過PDGF-C的刺激,VECs及MSCs細(xì)胞周期各時(shí)相的細(xì)胞數(shù)占細(xì)胞總數(shù)的百分比與對照組相比有明顯不同。其中,MSCs細(xì)胞周期中G1期細(xì)胞比例明顯降低(<0.05),S期細(xì)胞比例與對照組相比顯著增加(<0.05),G2+M期細(xì)胞比例變化不大(>0.05;圖4)。
PDGF-C同樣增加了VECs增殖期S期細(xì)胞比例(<0.05),G1期細(xì)胞比例明顯降低(<0.05),G2+M期細(xì)胞比例有所增加,但差異無統(tǒng)計(jì)學(xué)意義(>0.05;圖5)。
圖2 PDGF-C在不同濃度時(shí)對血管內(nèi)皮細(xì)胞增殖能力的影響
Figure 2 Effects of PDGF-C in different concentrations on VECs proliferation
PDGF-C: platelet-derived growth factor-C; VECs: vascular endothelial cells. PDGF-C promotes VECs proliferation in a dose-dependent manner. Compared with control group,*<0.05,**<0.01
圖3 PDGF-C在不同濃度時(shí)對間充質(zhì)干細(xì)胞增殖能力的影響
Figure 3 Effects of PDGF-C in different concentrations on MSCs proliferation
PDGF-C: platelet-derived growth factor-C; MSCs: mesenchymal stem cells. PDGF-C promotes MSCs proliferation, and MSCs proliferation reaches peak at 20μg/L concentration of PDGF-C. Compared with control group,*<0.05,**<0.01
圖4 PDGF-C對間充質(zhì)干細(xì)胞周期的影響
Figure 4 Effects of PDGF-C on MSCs phases
PDGF-C: platelet-derived growth factor-C; MSCs: mesenchymal stem cells. Compared with control MSCs,*<0.05
圖5 PDGF-C對血管內(nèi)皮細(xì)胞周期的影響
Figure 5 Effects of PDGF-C on VECs phases
PDGF-C: platelet-derived growth factor-C; VECs: vascular endothelial cells. Compared with control VECs,*<0.05
結(jié)果顯示,劃痕后,加入PDGF-C后的MSCs向空白處遷移的細(xì)胞數(shù)明顯多于對照組(圖6);VECs向空白處遷移的細(xì)胞有所增加,但遷移能力的增強(qiáng)不如MSCs明顯(圖7)。
培養(yǎng)24h后,可見VECs及MSCs遷移到小室底部膜的下室面,細(xì)胞遷出后,形態(tài)呈細(xì)長型。加入PDGF-C后,小室膜下室面VECs及MSCs數(shù)量都有增加,且對MSCs的遷移能力影響更大(圖8)。
內(nèi)皮細(xì)胞完整性的破壞是導(dǎo)致多種血管性疾病的重要原因,最常見的疾病就是動靜脈血栓的形成。因此,保護(hù)并維持血管內(nèi)膜完整性、減輕內(nèi)皮損傷及加快內(nèi)皮損傷修復(fù)是防治血管性疾病的關(guān)鍵環(huán)節(jié)。PDGF家族是維持組織正常生長的重要生長因子,PDGF-C是該家族成員之一,在多種正常組織多個(gè)階段都有表達(dá),參與生物體的生長發(fā)育。在成熟的組織中,PDGF-C主要表達(dá)于腎、睪丸、肝、心及中樞神經(jīng)系統(tǒng)等[6]。在脈管系統(tǒng)中,PDGF-C主要表達(dá)于血管平滑肌細(xì)胞[7]。PDGF-C通過結(jié)合并活化PDGF受體a(PDGFR-a),使信號傳遞進(jìn)入細(xì)胞[6],而其活化形式PDGF-CC不僅可和PDGFR-a的同型二聚體PDGFR-aa具有很高親和力,同時(shí)也可與PDGF-a/β異二聚體相結(jié)合[3,8],通過激活特異酪氨酸蛋白激酶,能促進(jìn)細(xì)胞DNA合成和分裂增殖[8]。多項(xiàng)實(shí)驗(yàn)研究表明PDGF-C有較強(qiáng)的促進(jìn)血管新生能力[2,3]。有研究顯示,灌注PDGF-C可促進(jìn)缺血心臟的血供重建及誘導(dǎo)缺血肢體的血管新生,這些多重生物學(xué)效應(yīng)是VEGF和bFGF等其他生長因子所不具備的獨(dú)特功能[4]。Banfi等[10]研究顯示PDGF-C能引起VEGF蛋白水平的上調(diào),通過使VEGF蛋白水平上調(diào)使血管局部VEGF濃度增高,動員更多內(nèi)皮祖細(xì)胞到達(dá)損傷部位,修復(fù)損傷的內(nèi)皮及促進(jìn)血管的新生[11]。
圖6 間充質(zhì)干細(xì)胞細(xì)胞遷移能力劃痕實(shí)驗(yàn)
Figure 6 Cell scratch test for detection of MSCs migration (×100)
PDGF-C: platelet-derived growth factor-C; MSCs: mesenchymal stem cells. A: control MSCs; B: PDGF-C treated MSCs
圖7 血管內(nèi)皮細(xì)胞細(xì)胞遷移能力劃痕實(shí)驗(yàn)
Figure 7 Cell scratch test for detection of VECs migration (×100)
PDGF-C: platelet-derived growth factor-C; VECs: vascular endothelial cells. A: control VECs; B: PDGF-C treated VECs
圖8 血管內(nèi)皮細(xì)胞及間充質(zhì)干細(xì)胞transwell遷移實(shí)驗(yàn)
Figure 8 Transwell assay for detection of VECs and MSCs migration at 24h (×100)
PDGF-C: platelet-derived growth factor-C; VECs: vascular endothelial cells; MSCs: mesenchymal stem cells. A: control VECs; B: PDGF-C treated VECs; C: control MSCs; D: PDGF-C treated MSCs
本實(shí)驗(yàn)證實(shí)PDGF-C能明顯促進(jìn)VECs和MSCs的增殖。流式細(xì)胞周期也證實(shí)了PDGF-C能刺激停滯于G0/G1期的細(xì)胞進(jìn)入分裂增殖周期,S期細(xì)胞比例增大,說明處于活躍的DNA復(fù)制與合成期的細(xì)胞量有所增加,這也證實(shí)了PDGF-C能促進(jìn)VECs及MSCs內(nèi)DNA的合成,加快有絲分裂及增殖。
PDGF-C在組織的損傷修復(fù)中不僅表現(xiàn)其絲裂原活性,同時(shí)能增加細(xì)胞的遷移能力。研究表明PDGF-C可促進(jìn)基質(zhì)金屬蛋白酶(matrix metalloproteinases,MMPs)的上調(diào)[12],MMPs通過其酶解能力,減少細(xì)胞外基質(zhì),從而促使細(xì)胞遷移[13],而MMP-2和MMP-9均可刺激局部組織血管的新生[14]。在細(xì)胞劃痕實(shí)驗(yàn)及Transwell細(xì)胞遷移實(shí)驗(yàn)中,觀察到20μg/L的PDGF-C能明顯促進(jìn)VECs及MSCs的遷移,而其對MSCs促進(jìn)作用更為明顯。
綜上所述,PDGF-C不但能增強(qiáng)VECs及MSCs的增殖能力,同時(shí)也能促進(jìn)其遷移。以上生物學(xué)作用可在血管損傷性疾病的防治中提供新思路,不但有效地增強(qiáng)內(nèi)皮細(xì)胞的增殖修復(fù),也可促進(jìn)干細(xì)胞在體內(nèi)的歸巢與遷移,共同促進(jìn)內(nèi)皮損傷后的修復(fù)。
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(編輯: 周宇紅)
Platelet-derived growth factor-C promotes proliferation and migration of vessel endothelial cells and mesenchymal stem cells
WANG Zi-Jing, QIAN Zhi-Yong, GUO Xi-Min, GAO De-Wei*
(Second Department of Geriatric Comprehensive Surgery, Chinese PLA General Hospital, Beijing 100853, China)
To determine the effect of platelet-derived growth factor-C (PDGF-C) on vascular endothelial cells (VECs) and mesenchymal stem cells(MSCs) culturedo.The VECs were isolated from thoracic aorta of SD rats and then cultured. Cryopreserved MSCs were cultured after water bath at 37℃. Cell counting and MTT assay were used to detect the effect of PDGF-C (0, 10, 20, 30, 40 and 50μg/L) on cell proliferation. Flow cytometry was used to detect cell phases. Transwell assay and cell scratch test were used to detect cell migration.PDGF-C significantly promoted the proliferation of VECs and MSCs, and increased the percentage of the cells arrested at S phase. Its effect on the VECs proliferation was found in a dose-dependent manner. PDGF-C of 20μg/L promoted the MSCs proliferation at a summit. PDGF-C also promoted the migration ability of cultured VECs and MSCs, especially on MSCs.PDGF-C promotes the proliferation and migration of cultured VECs and MSCs.
rats; platelet-derived growth factor-C; vascular endothelial cells; mesenchymal stem cells; cell proliferation; migration
R329.2+8
A
10.11915/j.issn.1671-5403.2015.08.142
2015?04?15;
2015?05?07
高德偉, E-mail: gaodw301@sina.com