骨髓间充质干细胞移植治疗视网膜病变

目前,对视网膜病变的治疗仍缺乏有效的药物.为解决视网膜损伤的修复问题,有研究者用胚胎干细胞、胚胎视网膜祖细胞、成体哺乳动物眼干细胞等进行了实验,但这些方法都存在着伦理学和移植学上的不足.骨髓间充质干细胞(bone marrow mesenchymal stem cells,BMSC)是骨髓中一类具有多向分化潜能的细胞群,在体外可诱导分化为神经元样细胞,进行BMSC移植,为视网膜病变的治疗提供了一条新的途径.现就BMSC生物学特征、体外的分离和纯化、向神经元样细胞的诱导分化及在视网膜病变治疗中的研究进展作一综述.     

干细胞移植治疗视网膜和视神经变性疾病的现状和进展

不可逆性的视网膜和视神经退行性变会导致视功能严重损伤甚至致盲.近年来,干细胞移植治疗视网膜和视神经损伤的研究进展为组织的修复和再生带来了希望.干细胞既可以用于细胞替代治疗,也可以通过分泌细胞因子发挥神经营养保护作用.胚胎干细胞、间充质干细胞、诱导多能干细胞和Müller细胞等各种来源的干细胞都极具发展前景,为眼科此类难治性疾病提供了丰富的资源.     

干细胞移植治疗视网膜变性疾病的研究进展

视网膜变性疾病是一类与遗传相关的变性疾病,导致患者渐进性视觉丢失,是主要的致盲性眼病之一,其共同病理基础是视网膜光感受器细胞的变性、坏死和凋亡,然而目前尚无有效的治疗方法。细胞移植治疗是目前实验研究治疗视网膜变性疾病的主要方法之一。近年研究表明将感光前体细胞或视网膜色素上皮细胞移植到视网膜下腔或玻璃体内,可以延缓宿主感光细胞的凋亡、替代凋亡的感光细胞、挽救残存的视觉功能和修复视网膜结构。细胞移植治疗的一个很重要的问题是移植细胞的来源问题,目前主要的移植细胞来源是视网膜祖／干细胞、胚胎干细胞和诱导多潜能干细胞等。本文就干细胞移植治疗视网膜变性疾病的研究进展进行综述。     

视网膜色素上皮细胞的诱导分化及其移植治疗方法的研究进展

视网膜色素上皮(retinal pigment epithelium,RPE)的病变可以导致多种视网膜疾病,目前缺乏有效的治疗手段.人类多能干细胞具有多向分化潜能,为此类疾病的细胞治疗提供了理想来源.本文将近年来胚胎干细胞和诱导多能干细胞体外定向分化为RPE细胞及移植治疗年龄相关性黄斑变性等视网膜疾病的研究进行了综述.     

视网膜色素上皮细胞的诱导分化及其移植治疗方法的研究进展

视网膜色素上皮(retinal pigment epithelium,RPE)的病变可以导致多种视网膜疾病,目前缺乏有效的治疗手段.人类多能干细胞具有多向分化潜能,为此类疾病的细胞治疗提供了理想来源.本文将近年来胚胎干细胞和诱导多能干细胞体外定向分化为RPE细胞及移植治疗年龄相关性黄斑变性等视网膜疾病的研究进行了综述.     

视网膜干细胞移植任重而道远

进行性视网膜感光细胞的死亡是许多视网膜变性疾病的共同特征。现有的治疗方法不能恢复已经丧失的视功能。视网膜干细胞移植研究的不断深入在为视网膜变性患者带来希望的同时也面临一些严峻挑战：如何获得理想的视网膜干细胞？如何诱导视网膜干细胞分化成视杆及视锥细胞？如何诱导移植的细胞与受体细胞形成功能性突触连接？感光细胞丧失的早期,内部的视网膜神经通路是完整的,新的感光细胞只需与双极细胞形成突触连接就能恢复完整的视网膜神经通路。而感光细胞替换通常比其它神经元更直接更容易。因为感光细胞是感觉神经元,只在一个方向上与双极细胞一水平细胞形成连接。另外,视网膜特殊的层状结构决定了视网膜外层的感光细胞层是视网膜干细胞移植最理想的位置。视网膜干细胞研究的进展、视网膜变性疾病的特征及视网膜的特殊结构让我们有理由相信,干细胞移植的成功将首先来自视网膜感光细胞移植。     

视网膜类器官3D培养技术的研究进展

视网膜退行性疾病引起的光感受器细胞损伤会导致患者视力受损,出现进行性视野缩小、视野缺损等临床症状。由于视网膜的免疫赦免特性,异体光感受器移植成为治疗视网膜退行性疾病的潜在方法,但光感受器的组织来源又成为一大难题。人胚胎干细胞是由3D培养诱导分化而成的视网膜类器官,可以作为视网膜组织来源之一,为类器官移植提供了供体材料。本文就3D培养技术在视网膜类器官培养中的应用、类器官移植存在的问题、类器官与临床应用的距离等展开综述。     

Müller细胞对大鼠光感受器变性及视功能的保护作用

目的以RCS视网膜色素变性大鼠为模型,研究经诱导产生神经干细胞特性的Müller细胞视网膜下腔移植对光感受器变性的保护作用。方法向6周龄VC大鼠玻璃体腔内注射神经毒素混合液（包含NMDA、kainate、FGF2和胰岛素）刺激视网膜Müller细胞。1周后取材分离Müller细胞体外原代培养。将细胞标记后,以每眼1×10^5个细胞密度移植到6周龄RCS大鼠右眼视网膜下腔,左眼分组注射正常Müller细胞和PBS作为同型对照及阴性对照。术后分别于第1、3、5、7周,行视网膜铺片、组织病理学及视觉电生理检查。结果培养的Müller细胞纯度可达96％以上,其中表达神经干细胞标志物的细胞占总细胞量的53％以上。组织病理学观察显示,在相同时间点移植眼保留的光感受器细胞数量明显较同型对照眼多,同型对照移植眼保留的光感受器细胞数量明显较阴性对照眼多。视网膜电图（ERG）检查结果与病理学结果相符。结论视网膜下腔移植经诱导产生神经干细胞特性的Müller细胞可以有效延缓RCS大鼠视网膜光感受器变性,为治疗视网膜变性疾病提供了新的途径。     

诱导多能干细胞在视网膜疾病研究中的应用

诱导多能干细胞(induced pluripotent stem cells,iPSCs)是成体细胞通过重编程而获得的一类具有胚胎干细胞相似特性和功能的细胞.近年来,iPSCs在再生医学和干细胞研究领域备受关注,尤其是患者特异源性iPSCs,来源方便、无免疫排斥和伦理学问题,同时还可以保留特定个体基因型,为再生医学以及细胞移植疗法提供了新的细胞来源.目前,iPSCs在视网膜疾病研究领域取得了长足的进步.本文主要对iPSCs向视网膜色素上皮细胞、感光细胞和神经节细胞的诱导分化及细胞移植研究、安全性评价等方面进行综述,探讨iPSCs在视网膜疾病研究中的应用和前景.     

Müller细胞对大鼠光感受器变性及视功能的保护作用

目的以RCS视网膜色素变性大鼠为模型,研究经诱导产生神经干细胞特性的Müller细胞视网膜下腔移植对光感受器变性的保护作用。方法向6周龄VC大鼠玻璃体腔内注射神经毒素混合液（包含NMDA、kainate、FGF2和胰岛素）刺激视网膜Müller细胞。1周后取材分离Müller细胞体外原代培养。将细胞标记后,以每眼1×10^5个细胞密度移植到6周龄RCS大鼠右眼视网膜下腔,左眼分组注射正常Müller细胞和PBS作为同型对照及阴性对照。术后分别于第1、3、5、7周,行视网膜铺片、组织病理学及视觉电生理检查。结果培养的Müller细胞纯度可达96％以上,其中表达神经干细胞标志物的细胞占总细胞量的53％以上。组织病理学观察显示,在相同时间点移植眼保留的光感受器细胞数量明显较同型对照眼多,同型对照移植眼保留的光感受器细胞数量明显较阴性对照眼多。视网膜电图（ERG）检查结果与病理学结果相符。结论视网膜下腔移植经诱导产生神经干细胞特性的Müller细胞可以有效延缓RCS大鼠视网膜光感受器变性,为治疗视网膜变性疾病提供了新的途径。     

视网膜内源性干细胞研究进展

视网膜的神经细胞一旦损伤,便无法再生修复,利用干细胞疗法使神经细胞得到再生修复已成为当今研究的热点.视网膜中存在具有自我修复能力的内源性干细胞,激活视网膜中的内源性干细胞,利用其对损伤的视网膜神经元进行修复,具有重要的研究价值和应用前景,近年来受到世界神经生物学、眼科学等领域研究者的重视.鱼类、两栖类动物的视网膜具有较强的再生修复能力,而鸟类和哺乳类动物的视网膜的再生能力有限,且各类动物的视网膜再生存在各自的特征.睫状体边缘带、视网膜色素上皮细胞、Müller细胞等细胞都是视网膜再生可能的细胞来源,如鱼类、鸟类和哺乳类动物新生成的视网膜细胞来自于视网膜Müller细胞,而两栖类动物再生的视网膜则来源于视网膜色素上皮细胞.各种视网膜内源性干细胞需要被活化后才能发挥干细胞特性对损伤的视网膜神经细胞进行修复,激活这些细胞的方法有多种,如利用兴奋性氨基酸、生长因子、转录因子、细胞内信号等.本文就不同物种,包括鱼类、两栖类、鸟类和哺乳类动物在内的视网膜的再生能力、睫状体边缘带、视网膜色素上皮细胞、Müller细胞等不同的视网膜内源性神经干细胞的来源及各种能够活化视网膜内源性干细胞进行增生和分化的因素的相关研究进展进行综述.     

Prospects for the application of Müller glia and their derivatives in retinal regenerative therapies

Neural cell death is the main feature of all retinal degenerative disorders that lead to blindness. Despite therapeutic advances, progression of retinal disease cannot always be prevented, and once neuronal cell damage occurs, visual loss cannot be reversed. Recent research in the stem cell field, and the identification of Müller glia with stem cell characteristics in the human eye, have provided hope for the use of these cells in retinal therapies to restore vision. Müller glial cells, which are the major structural cells of the retina, play a very important role in retinal homeostasis during health and disease. They are responsible for the spontaneous retinal regeneration observed in zebrafish and lower vertebrates during early postnatal life, and despite the presence of Müller glia with stem cell characteristics in the adult mammalian retina, there is no evidence that they promote regeneration in humans. Like many other stem cells and neurons derived from pluripotent stem cells, Müller glia with stem cell potential do not differentiate into retinal neurons or integrate into the retina when transplanted into the vitreous of experimental animals with retinal degeneration. However, despite their lack of integration, grafted Müller glia have been shown to induce partial restoration of visual function in spontaneous or induced experimental models of photoreceptor or retinal ganglion cell damage. This improvement in visual function observed after Müller cell transplantation has been ascribed to the release of neuroprotective factors that promote the repair and survival of damaged neurons. Due to the development and availability of pluripotent stem cell lines for therapeutic uses, derivation of Müller cells from retinal organoids formed by iPSC and ESC has provided more realistic prospects for the application of these cells to retinal therapies. Several opportunities for research in the regenerative field have also been unlocked in recent years due to a better understanding of the genomic and proteomic profiles of the developing and regenerating retina in zebrafish, providing the basis for further studies of the human retina. In addition, the increased interest on the nature and function of cellular organelle release and the characterization of molecular components of exosomes released by Müller glia, may help us to design new approaches that could be applied to the development of more effective treatments for retinal degenerative diseases.     

视网膜神经干细胞移植研究进展

视网膜退行性变可以导致视力严重受损甚至失明。来源于视网膜的神经干细胞具有向视网膜细胞分化的潜能,将其移植入退行性变的视网膜内可以实现视网膜部分功能的恢复。目前,有关视网膜神经干细胞体外培养、增殖、分化和移植方面的研究进展为视网膜组织再生及视功能的恢复带来了希望。     

Photoreceptor differentiation and integration of retinal progenitor cells transplanted into transgenic rats

Previous studies evaluating neural stem cells transplanted into the mature retina have demonstrated limited levels of graft-host integration and photoreceptor differentiation. The purpose of this investigation is to enhance photoreceptor cell differentiation and integration of retinal progenitor cells (RPC) following subretinal transplantation into retinal degenerate rats by optimization of isolation, expansion, and transplantation procedures. RPCs were isolated from human placental alkaline phosphatase (hPAP)-positive embryonic day 17 (E17) rat retina and expanded in serum-free defined media. RPCs at passage 2 underwent in vitro induction with all trans retinoic acid or were transplanted into the subretinal space of post-natal day (P) 17 S334ter-3 and S334ter-5 transgenic rats. Animals were examined post-operatively by ophthalmoscopy and optical coherence tomography (OCT) at weeks 1 and 4. Differentiation profiles of RPCs, both in vitro and in vivo were analysed microscopically by immunohistochemistry for various retinal cell specific markers. Our results demonstrated that the majority of passage 2 RPCs differentiated into retina-specific neurons expressing rhodopsin after in vitro induction. Following subretinal transplantation, grafted cells formed a multi-layer cellular sheet in the subretinal space in both S334ter-3 and S334ter-5 rats. Prominent retina-specific neuronal differentiation was observed in both rat lines as evidenced by recoverin or rhodopsin staining in 80% of grafted cells. Less than 5% of the grafted cells expressed glial fibrillary acidic protein. Synapsin-1 (label for nerve terminals) positive neural processes were present at the graft-host interface. Expression profiles of the grafted RPCs were similar to those of RPCs induced to differentiate in vitro using all-trans retinoic acid. In contrast to our previous study, grafted RPCs can demonstrate extensive rhodopsin expression, organize into layers, and show some features of apparent integration with the host retina following subretinal transplantation in slow and fast retinal degenerate rats. The similarity of the in vitro and in vivo RPC differentiation profiles suggests that intrinsic signals may have a significant contribution to RPC cell fate determination.     

干细胞诱导分化为视网膜色素上皮细胞的途径探讨

近年来,干细胞在眼科领域的研究及应用受到高度关注,胚胎干细胞(ES)、成体干细胞能够被定向诱导分化成视网膜色素上皮细胞,由此可获得转分化的大量的视网膜色素上皮细胞源,通过体内干细胞及视网膜色素上皮细胞移植有望应用于各种视网膜退行性疾病的细胞替代治疗。本文就各种干细胞诱导分化为视网膜色素上皮细胞的途径及应用进行探讨。     

Impact of xenotransplantation of multipotent mesenchymal stem cells of the bone marrow on the recovery of the structural organization and functional activity of the retina in its damage

Among the potential sources of cells for transplantation, the most promising autologous material for cell therapy and tissue engineering are multipotent mesenchymal stem cells (MMSC). The authors carried out an experiment dealing with MMSC xenotransplantation into the rabbit suprachoidal space on a model of laser retinal coagulation. For objective assessment of the magnitude and pattern of changes in the functional activity of different retinal cellular elements and the efficiency of MMSC transplantation, they performed electroretinographic and histological studies. The study indicated that MMSC transplantation into the suprachoroidal space is a safe and effective procedure for cell incorporation in order to treat retinal diseases. Electroretinography provided evidence that single MMSC transplantation better preserved the function of photoreceptors (a-wave). Histomorphometric studies demonstrated that the inserted cells stimulated reparative processes in the laser-induced damaged retina.     

骨髓间充质干细胞在视网膜移植领域的研究进展

临床上对于视网膜退行性疾病的治疗仍然只停留在改善循环、营养神经等支持治疗阶段,缺少特效的治疗方法,骨髓间充质干细胞(bone mesenchymal stem cells,BMSCs)是具有较强自我复制功能和多向分化潜能的一类细胞,人们开始通过尝试不同的分离、诱导、移植等手段,以实现其向视网膜细胞的转化,并最终实现体内的替代治疗。我们就BMSCs在视网膜移植领域的研究进展进行综述,以期为进一步的研究提供参考。     

骨髓间充质干细胞在角膜、视网膜及视神经疾病中的研究进展

骨髓间充质干细胞(BMSCs)是一种主要存在于骨髓中具有自我更新和多向分化潜能的干细胞.由于其具有体外无限增生、自我更新和能够分化成体内各种细胞的潜能,已经成为组织工程、细胞移植及基因治疗理想的靶细胞.在眼科相关研究中,BMSCs移植的研究主要集中于角膜病及视网膜疾病的治疗,视网膜疾病的治疗方式又可分为玻璃体腔注射和视网膜下移植,两者均有一定的治疗效果,而关于视神经疾病的治疗方面,国内外的研究较少.BMSCs的研究为解决当前眼科疾病治疗提供了新的思路和前景,但研究仍处于动物实验阶段,要进一步进行临床试验还有许多问题需要解决.就BMSCs的研究发展概况及其在眼科的研究进展进行综述.     

色素上皮细胞移植治疗视网膜变性疾病:问题与展望

近年来对色素上皮细胞移植如PRE移植、自体虹膜色素上皮细胞移植以及干细胞移植等作为视网膜变性疾病的再生性疗法进行了许多研究,为视网膜变性疾病开辟新的治疗途径。色素上皮细胞移植治疗更能直接地解决视网膜的局部问题。然而,多数方法尚处在实验和试验阶段及存在不足与风险,其手术适应证、手术方法、供体细胞来源、伦理问题、移植后细胞存活、免疫、生理功能等多种问题均亟待深入研究。