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)傷救治中心實驗室 遼寧省重癥創(chuàng)傷和器官保護重點實驗室，遼寧 沈陽 110016

·干細胞研究·

脂肪干細胞移植治療脊髓損傷研究進展

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)傷救治中心實驗室 遼寧省重癥創(chuàng)傷和器官保護重點實驗室，遼寧 沈陽 110016

脂肪干細胞； 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)濟負擔(dān)[1]。目前，我國經(jīng)濟的不斷發(fā)展，機動車事故、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，是指成熟的脂肪細胞在體內(nèi)聚集成團，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，并有機械性和審美功能。其在體內(nèi)含量豐富，含有的干祖細胞能夠分化為成骨細胞、軟骨細胞、脂肪細胞譜系等[5]。近年來，干細胞以其向多種組織細胞分化的能力而成為多種機體損傷的治療熱點，與骨髓間充質(zhì)干細胞和臍帶血干細胞等其他種類的干細胞相比，脂肪干細胞(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，ADSCs可以通過分泌各種細胞因子、調(diào)節(jié)炎癥反應(yīng)、改善缺氧、促進血管新生、抑制細胞凋亡或直接分化替代受損細胞，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方面的研究進展進行簡單概述。

1 ADSCs的神經(jīng)分化能力

神經(jīng)細胞由于分化程度高，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]，分化后的細胞可表達巢蛋白和神經(jīng)元特異性烯醇化酶等神經(jīng)細胞特異性標(biāo)志物，其形態(tài)也與神經(jīng)細胞相似。而Ji等[15]的研究更進一步表明，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更容易進行神經(jīng)分化。

2 ADSCs與骨髓間質(zhì)干細胞治療SCI比較

一些研究發(fā)現(xiàn)，神經(jīng)干細胞的標(biāo)記物在骨髓間質(zhì)干細胞(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中的使用[19]。因此，現(xiàn)在更多的使用堿性成纖維細胞生長因子和表皮生長因子進行神經(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，減少白細胞介素-1β等炎癥因子的表達，并減少凋亡反應(yīng)的發(fā)生，行為學(xué)實驗也證明其有助于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，相比于BMSCs，ADSCs表達BDNF、血管內(nèi)皮細胞生長因子(vascular endothelial cell growth factor，VEGF)與肝細胞生長因子(hepatocyte growth factor，HGF)的水平更高，更有增殖速度快、不易老化以及運動功能恢復(fù)更好等優(yōu)點[27]。

3 ADSCs治療SCI的可能機制

ADSCs治療SCI的可能機制中，其對血脊髓屏障的保護作用是其中之一。血脊髓屏障(blood spinal cord barrier，BSCB)主要由毛細血管基底膜、血管內(nèi)皮細胞、星形膠質(zhì)細胞等構(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和小膠質(zhì)細胞的活化，減少繼發(fā)性炎癥反應(yīng)和細胞凋亡，進而減少BSCB的破壞，促進大鼠后肢運動功能的恢復(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和白細胞介素-10并且抑制基質(zhì)金屬蛋白酶-9來進行免疫抑制，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[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能進入受損脊髓組織內(nèi)促進受損脊髓節(jié)段神經(jīng)元的修復(fù)，促進軸突再生，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驗室階段，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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全軍十二五面上項目(CSY12J002)；全軍重大新藥創(chuàng)制項目(2013ZX09J13109-02B)；全軍十二五面上項目(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