叢培芳， 柳云恩， 張玉彪， 佟昌慈， 史秀云， 劉 穎， 毛 舜， 佟 周， 施 琳， 金紅旭， 侯明曉

沈陽軍區(qū)總醫(yī)院 急診醫(yī)學(xué)部 全軍重癥(戰(zhàn))創(chuàng)傷救治中心實(shí)驗(yàn)室 遼寧省重癥創(chuàng)傷和器官保護(hù)重點(diǎn)實(shí)驗(yàn)室，遼寧 沈陽 110016

·干細(xì)胞研究·

脂肪干細(xì)胞移植治療脊髓損傷研究進(jìn)展

叢培芳， 柳云恩， 張玉彪， 佟昌慈， 史秀云， 劉 穎， 毛 舜，
佟 周， 施 琳， 金紅旭， 侯明曉

沈陽軍區(qū)總醫(yī)院 急診醫(yī)學(xué)部 全軍重癥(戰(zhàn))創(chuàng)傷救治中心實(shí)驗(yàn)室 遼寧省重癥創(chuàng)傷和器官保護(hù)重點(diǎn)實(shí)驗(yàn)室，遼寧 沈陽 110016

脂肪干細(xì)胞； 脊髓損傷； 血脊髓屏障

Adipose-derived stem cells； Spinal cord indury； Blood spinal cord barrier

脊髓損傷(spinal cord injury，SCI)由于其損傷位置的特殊性，常導(dǎo)致?lián)p傷平面以下肢體不可逆的神經(jīng)功能喪失，造成截癱、四肢癱等嚴(yán)重的并發(fā)癥，給工作和生活帶來毀滅性的打擊，同時，也為社會帶來沉重的經(jīng)濟(jì)負(fù)擔(dān)[1]。目前，我國經(jīng)濟(jì)的不斷發(fā)展，機(jī)動車事故、跌倒以及暴力行為等造成的SCI患者不斷增加，而治療卻僅限于早期使用大劑量類固醇和急性外科干預(yù)，以盡量減少脊髓水腫和隨后的繼發(fā)性或遲發(fā)性損傷[2-4]。因此，尋找治療SCI的有效手段已經(jīng)成為現(xiàn)代醫(yī)學(xué)工作者需要面對的一大難題。

脂肪組織是一種高度特化的結(jié)締組織，是指成熟的脂肪細(xì)胞在體內(nèi)聚集成團(tuán)，由薄層疏松結(jié)締組織分隔成小葉，不均勻地分布在身體的各個部位，并有機(jī)械性和審美功能。其在體內(nèi)含量豐富，含有的干祖細(xì)胞能夠分化為成骨細(xì)胞、軟骨細(xì)胞、脂肪細(xì)胞譜系等[5]。近年來，干細(xì)胞以其向多種組織細(xì)胞分化的能力而成為多種機(jī)體損傷的治療熱點(diǎn)，與骨髓間充質(zhì)干細(xì)胞和臍帶血干細(xì)胞等其他種類的干細(xì)胞相比，脂肪干細(xì)胞(adipose-derived stem cells，ADSCs)的獲取方式更為便利，并且不受特定時間限制，可通過微創(chuàng)的吸脂術(shù)大量獲取[6]。研究證實(shí)，ADSCs可以通過分泌各種細(xì)胞因子、調(diào)節(jié)炎癥反應(yīng)、改善缺氧、促進(jìn)血管新生、抑制細(xì)胞凋亡或直接分化替代受損細(xì)胞，協(xié)同治療難愈性創(chuàng)面、放射性膀胱損傷、放射性唾液腺損傷、造血功能障礙以及SCI等[7-12]。本研究就ADSCs治療SCI方面的研究進(jìn)展進(jìn)行簡單概述。

1 ADSCs的神經(jīng)分化能力

神經(jīng)細(xì)胞由于分化程度高，所以一旦受損，修復(fù)起來十分緩慢，嚴(yán)重時還可能造成不可修復(fù)的損傷。藥物對于修復(fù)神經(jīng)元的效果也不是十分理想，因此干細(xì)胞治療中，其具有的神經(jīng)分化能力對于SCI的修復(fù)十分重要。ADSCs具有很強(qiáng)的神經(jīng)分化能力，其分化方法方便，分化率高[13-14]，分化后的細(xì)胞可表達(dá)巢蛋白和神經(jīng)元特異性烯醇化酶等神經(jīng)細(xì)胞特異性標(biāo)志物，其形態(tài)也與神經(jīng)細(xì)胞相似。而Ji等[15]的研究更進(jìn)一步表明，在腦源性神經(jīng)營養(yǎng)因子(brain-derived neurotrophic factor，BDNF)和神經(jīng)營養(yǎng)因子-3(neurotrophin-3，NT-3)的誘導(dǎo)下，ADSCs更容易進(jìn)行神經(jīng)分化。

2 ADSCs與骨髓間質(zhì)干細(xì)胞治療SCI比較

一些研究發(fā)現(xiàn)，神經(jīng)干細(xì)胞的標(biāo)記物在骨髓間質(zhì)干細(xì)胞(bone marrow derived mesenchymal stem cells，BMSCs)與ADSCs中也有存在，表明二者均有神經(jīng)分化的潛能[16-17]。利用化學(xué)藥物，如β-巰基乙醇、二甲基亞砜和叔丁基羥基茴香醚可以使BMSCs分化為神經(jīng)球[18]，但分化中所使用的化學(xué)物質(zhì)的毒性限制了其在臨床試驗(yàn)中的使用[19]。因此，現(xiàn)在更多的使用堿性成纖維細(xì)胞生長因子和表皮生長因子進(jìn)行神經(jīng)分化誘導(dǎo)[20]。一直以來，BMSCs輔助治療SCI的研究更多，在治療中，BMSCs可以釋放神經(jīng)營養(yǎng)因子，減少白細(xì)胞介素-1β等炎癥因子的表達(dá)，并減少凋亡反應(yīng)的發(fā)生，行為學(xué)實(shí)驗(yàn)也證明其有助于SCI后功能的恢復(fù)，并且不良反應(yīng)很小[21-25]。

ADSCs進(jìn)行神經(jīng)分化誘導(dǎo)的方法與BMSCs相同，但Chung等[26]研究發(fā)現(xiàn)，ADSCs具有更強(qiáng)的神經(jīng)分化能力，在同等培養(yǎng)條件下，ADSCs可形成約500 μm的神經(jīng)球，而骨髓干細(xì)胞僅能形成不到100 μm直徑的神經(jīng)球，因此，同等量的ADSCs與BMSCs進(jìn)行神經(jīng)誘導(dǎo)分化的效率更高，治療效果也更好。另外，也有研究證實(shí)，相比于BMSCs，ADSCs表達(dá)BDNF、血管內(nèi)皮細(xì)胞生長因子(vascular endothelial cell growth factor，VEGF)與肝細(xì)胞生長因子(hepatocyte growth factor，HGF)的水平更高，更有增殖速度快、不易老化以及運(yùn)動功能恢復(fù)更好等優(yōu)點(diǎn)[27]。

3 ADSCs治療SCI的可能機(jī)制

ADSCs治療SCI的可能機(jī)制中，其對血脊髓屏障的保護(hù)作用是其中之一。血脊髓屏障(blood spinal cord barrier，BSCB)主要由毛細(xì)血管基底膜、血管內(nèi)皮細(xì)胞、星形膠質(zhì)細(xì)胞等構(gòu)成，對維持脊髓內(nèi)環(huán)境的穩(wěn)定、維持正常的神經(jīng)功能具有重要作用。其在SCI中的破壞通常被認(rèn)為是脊髓繼發(fā)性損傷加重的重要原因[28- 29]。SCI發(fā)生后，ADSCs移植可能通過抑制過氧化物酶的表達(dá)和小膠質(zhì)細(xì)胞的活化，減少繼發(fā)性炎癥反應(yīng)和細(xì)胞凋亡，進(jìn)而減少BSCB的破壞，促進(jìn)大鼠后肢運(yùn)動功能的恢復(fù)[30]。

缺氧、炎癥因子、理化損傷和水腫等同樣是造成SCI的原因[31-33]。多個研究表明，ADSCs可以通過分泌的前列腺素E2和白細(xì)胞介素-10并且抑制基質(zhì)金屬蛋白酶-9來進(jìn)行免疫抑制，同時可以下調(diào)炎癥反應(yīng)，緩解疼痛[34-36]。而由于其神經(jīng)分化的特性，ADSCs還可以分泌BDNF、親膽堿能神經(jīng)元因子(cholinergic neuronotrophic factor，CTNF)等神經(jīng)營養(yǎng)因子，進(jìn)一步的修復(fù)神經(jīng)損傷，有助于后續(xù)肢體功能上的恢復(fù)[6,37-39]。

4 經(jīng)神經(jīng)營養(yǎng)因子修飾的ADSCs治療脊髓損傷

ADSCs可以分泌神經(jīng)生長因子幫助損傷修復(fù)，而近年來，經(jīng)神經(jīng)營養(yǎng)因子修飾的ADSCs治療SCI更是研究的熱點(diǎn)[40-42]。多個研究表明，經(jīng)BDNF、17β-雌二醇和神經(jīng)鈣黏蛋白等修飾的ADSCs能進(jìn)入受損脊髓組織內(nèi)促進(jìn)受損脊髓節(jié)段神經(jīng)元的修復(fù)，促進(jìn)軸突再生，并能有效縮短神經(jīng)元的修復(fù)時間[43-46]。熊敏等[43]研究發(fā)現(xiàn)，ADSCs對于SCI大鼠可有顯著的治療效果，而經(jīng)BDNF轉(zhuǎn)染的ADSCs移植于SCI大鼠與單純應(yīng)用ADSCs治療的SCI大鼠相比，其運(yùn)動功能評分(Basso Beattie Bresnahan,BBB)明顯更高，BDNF和神經(jīng)生長因子的表達(dá)也更多，神經(jīng)損傷標(biāo)志物神經(jīng)膠質(zhì)纖維酸性蛋白的表達(dá)則被抑制，表明經(jīng)BDNF轉(zhuǎn)染的ADSCs治療SCI大鼠，其神經(jīng)結(jié)構(gòu)以及神經(jīng)功能恢復(fù)更好。

綜上所述，ADSCs對于SCI的恢復(fù)具有積極作用，其易獲得性、神經(jīng)分化率高等特點(diǎn)相比于BMSCs而言，更有利于臨床的應(yīng)用。但其現(xiàn)今研究大都仍停留在實(shí)驗(yàn)室階段，研究結(jié)果缺乏有效的臨床數(shù)據(jù)的支持。有理由相信，隨著研究的不斷深入，ADSCs將在SCI治療中發(fā)揮更大作用，為更多的患者帶來福音。

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全軍十二五面上項(xiàng)目(CSY12J002)；全軍重大新藥創(chuàng)制項(xiàng)目(2013ZX09J13109-02B)；全軍十二五面上項(xiàng)目(CSY13J002)；總后衛(wèi)生部重大新上(ASM14L008)

叢培芳(1987-)，女，遼寧沈陽人，藥師，碩士

侯明曉，E-mail：houmingxiao188@163.com

2095-5561(2017)05-0298-04DOI∶10.16048/j.issn.2095-5561.2017.05.10

2017-09-08