葉冬梅,陳 琛,沈 梅
(1. 大連大學(xué)附屬中山醫(yī)院 康復(fù)醫(yī)學(xué)科,遼寧 大連 116001;2. 大連大學(xué)醫(yī)學(xué)院 解剖學(xué)教研室, 遼寧 大連 116622)
國(guó)家自然科學(xué)基金項(xiàng)目(81601982)
葉冬梅(1980-),女,主治醫(yī)師。E-mail: shuiyan_1980@163.com
沈 梅,教授。E-mail: pyf0404@126.com
論著
10.11724/jdmu.2017.05.02
微波對(duì)骨折愈合過程中骨髓間充質(zhì)干細(xì)胞遷移能力的影響
葉冬梅1,陳 琛2,沈 梅1
(1. 大連大學(xué)附屬中山醫(yī)院 康復(fù)醫(yī)學(xué)科,遼寧 大連 116001;2. 大連大學(xué)醫(yī)學(xué)院 解剖學(xué)教研室, 遼寧 大連 116622)
目的探討微波電療法對(duì)骨折愈合過程中骨髓間充質(zhì)干細(xì)胞(BMSC)遷移能力的影響。方法將30只SD大鼠建骨折模型后隨機(jī)分成兩組(對(duì)照組、實(shí)驗(yàn)組各15只),實(shí)驗(yàn)組微波治療30 d,對(duì)照組不予治療,采用X線平片觀察第10天及第30天兩組大鼠骨折愈合的情況;另取3只SD大鼠分離BMSC體外培養(yǎng),對(duì)照組正常培養(yǎng),實(shí)驗(yàn)組進(jìn)行0.5 W/cm2微波照射60 min,采用劃痕實(shí)驗(yàn)、transwell小室實(shí)驗(yàn)評(píng)價(jià)兩組BMSC的遷移能力;采用 Western-blot檢測(cè)兩組BMSC中HIF-1、VEGF、FGF、PDGF、IGF-1的表達(dá)。結(jié)果X線平片結(jié)果表明照射第10天對(duì)照組與實(shí)驗(yàn)組射線相對(duì)密度分別為(0.81±0.10)和(0.94±0.13),差異有統(tǒng)計(jì)學(xué)意義(P=0.02),而第30天兩組分別為(0.96±0.12)和(0.99±0.09),差異無統(tǒng)計(jì)學(xué)意義。劃痕實(shí)驗(yàn)對(duì)照組距離基線遷移距離(192±15)μm,實(shí)驗(yàn)組遷移距離(430±21)μm,差異具有統(tǒng)計(jì)學(xué)意義(P=0.01)。Transwell小室實(shí)驗(yàn)對(duì)照組遷移細(xì)胞數(shù)(68±18)個(gè),實(shí)驗(yàn)組遷移細(xì)胞數(shù)(112±25)個(gè),差異具有統(tǒng)計(jì)學(xué)意義(P=0.02)。Western blot結(jié)果表明,與對(duì)照組比較,實(shí)驗(yàn)組BMSC中HIF-1及VEGF表達(dá)顯著升高(均P<0.05),而FGF、PDGF、IGF-1表達(dá)兩組間差異不顯著。結(jié)論微波可能通過促進(jìn)骨髓間充質(zhì)干細(xì)胞遷移而影響骨折愈合。
微波;骨髓間充質(zhì)干細(xì)胞;缺氧誘導(dǎo)因子-1;骨折愈合
骨髓間充質(zhì)干細(xì)胞(Bone Mesenchymal Stem cells, BMSC)是成體干細(xì)胞的一種,有自我更新及多向分化潛能[1]?,F(xiàn)已證實(shí)骨折的修復(fù)過程中亦存在干細(xì)胞歸巢[2]。微波電療法被應(yīng)用于促進(jìn)骨折愈合的輔助手術(shù)及保守治療中已有很長(zhǎng)的歷史,但缺乏對(duì)其機(jī)制的深入探討。有研究表明脈沖電磁場(chǎng)可以提高細(xì)胞的定向遷移[3-4]。本研究擬觀察微波對(duì)骨折愈合中BMSC遷移的影響。
8周齡雄性SD大鼠30只,質(zhì)量228~251 g,手術(shù)建立大鼠股骨干骨折模型。 3.5%的水合氯醛(1 mL/100 g)行腹腔麻醉,成功后剃毛、消毒、鋪巾,取左下肢髕骨外側(cè)緣縱行切口,逐層切開皮膚及部分股四頭肌腱性組織,屈曲膝關(guān)節(jié)并向內(nèi)側(cè)脫位髕骨,清楚顯露股骨髁間凹。利用1根5 mL注射器針頭在股骨髁間凹處開口,逆行插入克氏針并沿髓腔穿至股骨粗隆間。剪斷多余的克氏針,并將其遠(yuǎn)端埋于股骨髁間骨皮質(zhì)下。碘伏及0.9%氯化鈉溶液反復(fù)沖洗切口后,使用3-0絲線逐層縫合切口。將術(shù)畢大鼠轉(zhuǎn)移到自制閉合骨折制備器載物臺(tái)上,右大腿置于沖擊臺(tái)上,用 200 g 砝碼從 17~20 cm 高處落下(根據(jù)大鼠體重適度調(diào)整),使該側(cè)肢體股骨干骨折。全部實(shí)驗(yàn)大鼠于造模后立即行X線股骨正位平片評(píng)價(jià)骨折情況,確定模型建立成功。
將30只骨折建模大鼠隨機(jī)分成兩組(對(duì)照組和實(shí)驗(yàn)組各15只),根據(jù)既往研究[5],實(shí)驗(yàn)組給予2450 MHz 微波連續(xù)波型0.5 W /cm2照射,15 min/d,連續(xù)治療30 d。對(duì)照組動(dòng)物不給予微波治療。于治療第10天及30天,行X線評(píng)價(jià)骨折愈合情況。
另取正常雄性SD大鼠3只,斷頸處死,取股骨和脛骨,用手術(shù)剪將股骨和脛骨的骨骺端剪掉,露出骨髓腔,用添加雙抗DMEM/F12 培養(yǎng)基沖出骨髓,收集骨髓細(xì)胞懸液移入細(xì)胞培養(yǎng)瓶中。細(xì)胞培養(yǎng)于10%胎牛血清的DMEM/F12培養(yǎng)液中,定時(shí)換液并去掉未貼壁細(xì)胞。流式細(xì)胞術(shù)鑒定BMSC:CD90+、CD44+、CD45-。取生長(zhǎng)良好的第3~7代BMSC細(xì)胞進(jìn)行細(xì)胞學(xué)及分子生物學(xué)實(shí)驗(yàn)。
BMSC細(xì)胞接種于24孔板,約2×105個(gè)/孔,培養(yǎng)24 h長(zhǎng)滿后于細(xì)胞密集處用200 μL槍頭劃痕,用PBS緩沖液沖洗。根據(jù)既往研究[5],實(shí)驗(yàn)組給予0.5 W/cm2照射60 min,對(duì)照組不給予照射,觀察并測(cè)量?jī)山M0 h及24 h后細(xì)胞遷移情況。
采用transwell 小室(膜孔0.8 μm),上室接種2×105個(gè)BMSC,接種后實(shí)驗(yàn)組給予0.5 W/cm2照射60 min,對(duì)照組不給予照射,24 h后取膜染色,200倍光鏡下隨機(jī)計(jì)數(shù)6個(gè)視野中細(xì)胞個(gè)數(shù),求均值及標(biāo)準(zhǔn)差。
實(shí)驗(yàn)組給予0.5 W/cm2照射60 min,對(duì)照組不給予照射。24 h后分別將對(duì)照組及實(shí)驗(yàn)組2×107細(xì)胞加入0.2 mL蛋白裂解液裂解30 min,4 ℃、3000 r/min離心20 min,取上清。BSA法測(cè)定總蛋白濃度,取等質(zhì)量總蛋白(30 μg),95 °C變性10 min,經(jīng)10%SDS-PAGE電泳分離蛋白質(zhì)后在Bio-Rad濕轉(zhuǎn)電泳槽中恒壓100 V轉(zhuǎn)膜70 min,5%脫脂奶粉中室溫封閉1 h,一抗4 °C搖床過夜乏氧誘導(dǎo)因子-1α(hypoxia inducible factor 1α, HIF-1α)抗體1∶4000稀釋(abcom),血管內(nèi)皮生長(zhǎng)因子(vascular endothelial growth factor, VEGF)抗體1∶2000稀釋(abcom),成纖維細(xì)胞生長(zhǎng)因子(fibroblast growth factor, FGF)抗體1∶2000稀釋(Invitrogen),血小板源性生長(zhǎng)因子(platelet-derived growth factor, PDGF)抗體1∶2000稀釋(abcom),胰島素樣生長(zhǎng)因子(insulin and insulin-like growth factor-1, IGF-1)抗體1∶3000稀釋(abcom),TBS洗膜3次,每次5 min,二抗室溫?fù)u床2 h,TBS洗膜3次,每次5 min,ECL顯影。以β-actin作為內(nèi)參,抗體1∶4000稀釋(Sigma),余步驟同上。
照射第10天實(shí)驗(yàn)組骨折愈合處相對(duì)射線密度為 (0.94±0.13),與對(duì)照組(0.81±0.10)相比差異有統(tǒng)計(jì)學(xué)意義(P=0.02)。而第30天實(shí)驗(yàn)組骨折愈合處相對(duì)射線密度(0.99±0.09),與對(duì)照組(0.96±0.12)相比差異沒有統(tǒng)計(jì)學(xué)意義(P=0.41)。見圖1。
A:大鼠股骨干骨折X線股骨正位平片;B:X線攝片分析。*:與對(duì)照組比較,P<0.05圖1 大鼠股骨干骨折X線攝片分析Fig 1 Radiographs of rat femur and the radiographs analysis
劃痕實(shí)驗(yàn)24 h后計(jì)算遷移細(xì)胞數(shù),對(duì)照組距離基線遷移距離(192±15)μm,實(shí)驗(yàn)組遷移距離(430±21)μm,差異具有統(tǒng)計(jì)學(xué)意義(P=0.01),見圖2。Transwell 小室實(shí)驗(yàn)24 h后計(jì)算跨膜細(xì)胞數(shù),對(duì)照組遷移細(xì)胞數(shù)(68±18)個(gè),實(shí)驗(yàn)組遷移細(xì)胞數(shù)(112±25)個(gè),差異具有統(tǒng)計(jì)學(xué)意義(P=0.02),見圖3。
A:BMSC體外劃痕實(shí)驗(yàn)光鏡照片(×100);B:遷移距離統(tǒng)計(jì)分析。*:與對(duì)照組比較,P< 0.05圖2 BMSC體外劃痕實(shí)驗(yàn)Fig 2 In vitro scratch assay for BMSC
Western blot檢測(cè)發(fā)現(xiàn),與對(duì)照組比較,微波照射后BMSC中HIF-1及VEGF表達(dá)顯著升高(均P<0.05)。而FGF、PDGF、IGF-1表達(dá)兩組間差異無統(tǒng)計(jì)學(xué)意義。見圖4。
研究表明,在骨折修復(fù)過程中源于干細(xì)胞的骨組織修復(fù)超過15%,而骨髓則是骨缺損修復(fù)的干細(xì)胞的重要來源[6]。在局部微環(huán)境的誘導(dǎo)下,BMSC向某些特異性組織聚集、遷移,誘導(dǎo)分化成組織修復(fù)所需的細(xì)胞,促進(jìn)損傷組織的修復(fù),這一過程稱為歸巢[7]。骨修復(fù)過程需要在骨折處聚集足夠數(shù)量的BMSC遷移至損傷處。研究表明,骨折發(fā)生后外周血中BMSC增多,3 d后達(dá)到高峰,表明動(dòng)員全身各處的間充質(zhì)干細(xì)胞歸巢到骨折處也是骨折良好修復(fù)的早期事件。
微波療法被應(yīng)用于輔助手術(shù)及保守治療促進(jìn)骨折愈合。本研究結(jié)果表明,微波對(duì)骨愈合的促進(jìn)作用在骨折愈合早期(10 d)作用較為明顯。類似的結(jié)果在早前亦有報(bào)道[8]。而BMSC向骨損傷區(qū)域定向歸巢是骨損傷修復(fù)過程的早期事件,因此推測(cè)微波通過影響B(tài)MSC募集、遷移而在骨折愈合早期發(fā)揮作用。
A:BMSC transwell 小室實(shí)驗(yàn)光鏡照片(×200); B:跨膜細(xì)胞計(jì)數(shù)統(tǒng)計(jì)分析。*與對(duì)照組比較, P<0.05圖3 BMSC transwell 小室實(shí)驗(yàn)Fig 3 Transwell assay for BMSC
A:BMSC骨折相關(guān)因子蛋白表達(dá)Western blot 檢測(cè)結(jié)果;B:表達(dá)量統(tǒng)計(jì)分析。*:與對(duì)照組比較,P<0.05圖4 Western blot 檢測(cè)微波照射骨折愈合相關(guān)蛋白表達(dá)Fig 4 Western blot results of protein expression levels after microwave exposure
微波是一種高頻電磁波,熱效應(yīng)是其對(duì)生物體治療效應(yīng)之一,但不合理的治療劑量會(huì)導(dǎo)致熱損傷。在前期研究中,為了確定微波對(duì)細(xì)胞及組織的照射安全劑量,我們采用抗干擾光纖測(cè)溫儀測(cè)量不同功率微波照射細(xì)胞、局部組織溫度變化,并采用光鏡、電鏡的方法評(píng)價(jià)照射局部組織熱損傷,得出結(jié)論:低于0.5 W/cm2不會(huì)導(dǎo)致局部熱損傷[5]。
為了驗(yàn)證微波是否可以影響B(tài)MSC遷移,本研究進(jìn)行了劃痕實(shí)驗(yàn)及transwell小室實(shí)驗(yàn)。兩實(shí)驗(yàn)結(jié)果均表明,微波可以促進(jìn)BMSC體外遷移能力。既往有研究表明脈沖電磁場(chǎng)可以提高卵巢癌細(xì)胞SKOV3的遷移能力[3],促進(jìn)腦室底神經(jīng)干細(xì)胞向白質(zhì)損傷區(qū)域募集[4],促進(jìn)巨噬細(xì)胞遷移至骨損傷局部[9],表明電磁場(chǎng)可影響細(xì)胞的定向遷移能力。
骨折愈合是一個(gè)復(fù)雜而連續(xù)的過程,從組織學(xué)和細(xì)胞學(xué)的變化,通常將其分為4個(gè)階段:(1)血腫炎癥機(jī)化期,骨折導(dǎo)致骨髓腔、骨膜下和周圍組織血管破裂出血,血腫形成,局部逐漸清除血凝塊、壞死軟組織,而使血腫機(jī)化形成肉芽組織。在這個(gè)階段成纖維細(xì)胞生長(zhǎng)因子(fibroblast growth factor,F(xiàn)GF)在局部高表達(dá),bFGF 與成骨細(xì)胞表面的受體結(jié)合后,能使其向成骨細(xì)胞轉(zhuǎn)化[10]。初同偉等[11]發(fā)現(xiàn)VEGF在骨折愈合的早期表達(dá)量高,在骨折愈合過程中對(duì)于骨折斷端的血管生成發(fā)揮了極大的作用。(2)纖維骨痂形成期,骨內(nèi)、外膜增生,新生血管長(zhǎng)入,成骨細(xì)胞大量增生,逐漸形成纖維骨痂。在這個(gè)時(shí)期,骨成型蛋白質(zhì)(bone morphogenetic protein,BMP)及轉(zhuǎn)化生長(zhǎng)因子β(transforming growth factor β,TGF-β)表達(dá)逐漸達(dá)到高峰。研究發(fā)現(xiàn),TGF-β能使BMP的骨誘導(dǎo)能力加強(qiáng),能夠誘導(dǎo)間充質(zhì)細(xì)胞合成軟骨特異性蛋白聚糖[12]。其中,TGF-β能抑制新的破骨細(xì)胞形成,使破骨細(xì)胞死亡,從而促進(jìn)成骨細(xì)胞的增殖,刺激纖骨基質(zhì)蛋白產(chǎn)生,刺激新骨質(zhì)形成,刺激骨鈣化[13]。(3)骨性骨痂形成期,成骨細(xì)胞合成并分泌骨基質(zhì),使骨折端內(nèi)、外形成的骨樣組織逐漸骨化,形成新骨,由骨內(nèi)、外膜緊貼骨皮質(zhì)內(nèi)、外形成內(nèi)骨痂和外骨痂,骨痂不斷鈣化加強(qiáng),當(dāng)其達(dá)到足以抵抗肌收縮及成角剪力和旋轉(zhuǎn)力時(shí),則骨折已達(dá)到臨床愈合[10]。此期,骨保護(hù)素、I型膠原、骨鈣素等基因表達(dá)上調(diào),促進(jìn)骨痂鈣化[14]。(4)骨板形成塑形期,原始骨痂中新生骨小梁增粗,排列逐漸規(guī)則和致密,原始骨痂被板層骨所替代,使骨折部位形成堅(jiān)強(qiáng)的骨性連接。這一過程是骨組織力學(xué)塑性的過程,隨著肢體活動(dòng)和負(fù)重,使多余的骨痂被吸收而清除,髄腔重新溝通,骨折回復(fù)正常骨結(jié)構(gòu)[13]。本研究Western blot檢測(cè)了骨折早期相關(guān)因子的表達(dá),結(jié)果表明 HIF-1表達(dá)顯著升高。研究表明,在缺氧條件下骨痂組織中包括成骨細(xì)胞在內(nèi)可調(diào)節(jié)細(xì)胞缺氧反應(yīng)的重要的轉(zhuǎn)錄因子HIF-1表達(dá)增多,從而促進(jìn)其下游的多種因子(如SDF-1/CXCR4、ERK1/2等)上調(diào)[15]。HIF-1 是細(xì)胞在低氧條件下產(chǎn)生的核蛋白,它與靶基因結(jié)合,促進(jìn)其轉(zhuǎn)錄。既往研究結(jié)果表明,微波輻射上調(diào)大鼠腦HIF-1α表達(dá),可通過ERK及PI3K通路上調(diào)HIF-1的活性[16-17]。因此,微波可能通過HIF-1介導(dǎo)增加BMSC遷移能力而促進(jìn)骨折愈合。
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MicrowavetherapypromotingfracturehealingbyenhancingBMSCsmigration
YE Dongmei1, CHEN Chen2, SHEN Mei1
(1.DepartmentofRehabilitation,AffiliatedZhongshanHospitalofDalianUniversity,Dalian116001,China;2.DepartmentofAnatomy,MedicalCollegeofDalianUniversity,Dalian116622,China)
ObjectiveThe current studied aimed to study the effect of microwave to the migration of BMSC during the healing of fracture.MethodsThirty animals were divided into two groups (15 in each group). For the treatment group, it was provided a 30-day microwave therapy of (0.5 W/cm2, 60 min/d) , but not for the control group. The effect of microwave therapy on fracture repair in a rat femoral fracture model was evaluated by X-ray on the 10th and 30th day. To identify the influence of microwave on BMSCs migration, the scratch assay and transwell assay were employed in vitro. A preliminary study of factors expression by western blot including HIF-1, VEGF, FGF, PDGF and IGF-1.ResultsThe Radiographic density of the fracture gap were (0.81±0.10) for control group and (0.94±0.13) for treatment group. Radiographic assessments showed that fracture healing was accelerated especially on the 10th day of the microwave treatment (P=0.02) but not statistically significant at 30th day (0.96±0.12) and (0.99±0.09),P>0.05). In scratch test, the migration distance of BMSC was (192±15)μm in control group and (430±21)μm in treatment group (P=0.01). In transwell test, the number of transmembrane cells were (68±18) in control group and (112±25) in treatment group (P=0.02). The results of scratch and transwell assay indicated that the BMSCs migration was promoted by microwave. HIF-1 and VEGF protein expression levels increased after microwave exposure (eachP<0.05). But there was no significant difference in the expression of FGF, PDGF and IGF-1 with or without microwave exposure (eachP>0.05) .ConclusionMicrowave therapy promoting fracture healing by enhancing bmscs migration.
microwave;BMSC;HIF-1;fracture healing
R683.42
A
1671-7295(2017)05-0423-05
葉冬梅,陳琛,沈梅.微波對(duì)骨折愈合過程中骨髓間充質(zhì)干細(xì)胞遷移能力的影響[J].大連醫(yī)科大學(xué)學(xué)報(bào),2017,39(5):423-427.
2016-12-04;
2017-09-20)