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。     

视网膜类器官衍生物的研究应用

视网膜退行性疾病的种类繁多、患病人口基数大,该病特征为终末期严重的视网膜细胞丢失。视网膜类器官(retinal organoid,RO)可通过3D干细胞体外分化培养技术大量获取,并拥有完整的各亚型视网膜细胞和经典的视网膜分层结构。因此,RO可作为最佳的视网膜退行性疾病建模方法之一,以便于发现潜在致病机制。目前,RO衍生物已被广泛用于视网膜细胞替代治疗的动物实验和临床研究,具体的成效参差不齐,可能的影响因素包括移植细胞数量、移植时间窗、移植工具等。随着RO相关研究的快速发展,视网膜退行性疾病在分子和个体上的诊断和治疗将进一步完善。     

重视不同来源移植细胞在视网膜退行性疾病中的替代治疗作用

视网膜退行性疾病是导致不可逆性视力损害和失明的主要原因之一,尚无有效的治疗方法。细胞疗法因具有替代受损或丧失功能细胞的作用,在视网膜退行性疾病的再生医学中受到广泛关注。不同来源移植细胞的替代治疗在基础研究和临床试验中显示了一定的安全性和有效性,但仍存在伦理、免疫排斥、致瘤性等不足。病变区微环境也影响着移植细胞的存活,使细胞替代治疗的临床应用受到阻碍。随着移植细胞种类增加和移植技术更新,通过重编程、基因修饰、三维培养和生物支架等的应用,视网膜退行性疾病的细胞替代治疗效果得到不断优化。不同学科间交叉合作有效解决了不同来源移植细胞的一些潜在问题,在细胞悬液、细胞膜片和视网膜类器官替代治疗视网膜退行性疾病方面取得显著进展。     

光感受器移植在视网膜退行性疾病中的应用研究进展

视网膜退行性疾病是影响人类视力的主要疾病，使人感光细胞受损，损害人的视力。而且哺乳动物的视网膜没有再生能力，一旦患病会严重影响人们的正常生活。目前尚未有明确的预防和减缓该类疾病的方法，但移植光感受器以补充视网膜中受损的感光细胞可以治疗视网膜疾病。本文将讨论光感受器移植方法在视网膜退行性疾病中恢复视力的现状和移植技术。     

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。     

视网膜感光细胞的移植

近十年多来,视网膜移植的研究已取得了很大进步,它可分为视网膜植片移植和视网膜细胞移植。细胞移植的前景十分广阔,它包括基因转移作为治疗方法的潜力巨大。目前,视网膜细胞移植中研究较多是色素上皮细胞(RPE)和感光细胞的移植。视网膜感光细胞移植开始于80年代中期,对感光细胞变性的疾病,移植纯的感光细胞具有针对性,且能减少玫瑰花结构的形成。我们拟就近年来视网膜感光细胞的移植的有关问题作一综述。一、移植细胞的分离和纯化分离出足够数量和适当纯度的细胞以替代受体功能不全的细胞是细胞移植最关键的第一步。为使移植细胞能更好发…     

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。     

可溶性因子在视网膜移植中的作用

视网膜移植是治疗视网膜疾病的一种新方法，通过细胞与局部微环境中的可溶性因子的相互作用，视网膜前体细胞可以发育成特定的细胞类型。本文主要对可溶性因子在视网膜前体细胞诱导分化为感光细胞中的作用作一综述。     

可溶性因子在视网膜移植中的作用

视网膜移植是治疗视网膜疾病的一种新方法,通过细胞与局部微环境中的可溶性因子的相互作用,视网膜前体细胞可以发育成特定的细胞类型。本文主要对可溶性因子在视网膜前体细胞诱导分化为感光细胞中的作用作一综述。     

视网膜的细胞移植

随着神经生物学的迅速发展，神经的移植及再生问题成为生命科学的一大研究热点，近年来开展的视网膜移植技术也取得了较大的进展。本综合阐述了最近在视网膜的色素上皮及感光细胞移植方面的研究进展，这些就成为眼底疾病的治疗提供了更为广阔的前景。     

快速退变性视网膜变性感光细胞超微结构变化分析

目的 了解快速退变性遗传性视网膜变性的感光细胞在出生后早期发生的形态学变化,为临床治疗提供依据.方法 取出生后不同时间的rd小鼠及正常对照小鼠各6只的视网膜,经光镜、扫描电镜和透射电镜观察感光细胞的形态发生发育和结构变化过程,比较二者的动态变化和形态学差异.结果 rd鼠生后1周开始出现感光细胞节段变短,内节段内线粒体变性改变多见;偶见感光细胞核旁胞浆内出现肿胀变形的线粒体.2周时节段层变薄,内节段结构已不完整,外节膜盘少见,变形且排列不整齐;外核层细胞层数明显减少,可见核固缩及染色质凝聚,偶见外丛状层部分神经突起内出现变性的线粒体.3周时节段层近消失,外核层只剩一层细胞,胞浆内可见髓样结构;外丛状层变薄.4周时内节段高度变形,视网膜色素上皮层与外核层之间出现大量不成形结构.外核层仅残存少许胞体,胞浆内出现多量不成形结构.外丛状层极薄,部分区域已消失.结论 rd鼠在出生后早期就发生感光细胞的变性改变,细胞内线粒体改变明显.其感光细胞变性发生早,进展快,呈快速退变特点.     

Prosthetic vision: devices,patient outcomes and retinal research

Retinal disease and its associated retinal degeneration can lead to the loss of photoreceptors and therefore, profound blindness. While retinal degeneration destroys the photoreceptors, the neural circuits that convey information from the eye to the brain are sufficiently preserved to make it possible to restore sight using prosthetic devices. Typically, these devices consist of a digital camera and an implantable neurostimulator. The image sensor in a digital camera has the same spatiotopic arrangement as the photoreceptors of the retina. Therefore, it is possible to extract meaningful spatial information from an image and deliver it via an array of stimulating electrodes directly to the surviving retinal circuits. Here, we review the structure and function of normal and degenerate retina. The different approaches to prosthetic implant design are described in the context of human and preclinical trials. In the last section, we review studies of electrical properties of the retina and its response to electrical stimulation. These types of investigation are currently assessing a number of key challenges identified in human trials, including stimulation efficacy, spatial localisation, desensitisation to repetitive stimulation and selective activation of retinal cell populations.     

诱导多能干细胞向神经视网膜细胞定向分化的研究进展

视网膜退行性病变是造成视觉损害乃至失明的重要原因,由于成年视网膜组织无法自我更新病变中丢失的细胞,导致视网膜退行性病变具有不可逆性。诱导多能干细胞具有自我更新和多向分化的巨大潜力,是建立疾病模型、研究细胞替代疗法的理想供体。本文重点论述诱导多能干细胞的获取及其向神经视网膜细胞定向分化方面的研究进展,为视网膜退行性病变的实验室研究和临床诊治提供一定参考。     

Biology and therapeutic potential of adult retinal stem cells

Retinal degeneration encompasses a constellation of common pathologies for which there is no regenerative treatment. Vision loss has a devastating impact on quality of life and activities of daily living. Pharmacologic treatments serve to stave off disease progression but do not represent a restorative approach. Cellular transplantation is considered to be a promising approach for future therapy for retinal degeneration. There are, however, significant barriers that must be overcome if cell transplantation is to become a clinical reality. In this review, we focus on the need for a cellular replacement therapy for retinal disease and the promise of stem cells as candidate cellular therapeutics. In particular, we discuss the origins of stem cells in the retina, the discovery and characterization of retinal stem cells isolated from adult humans, and their transplantation potential and clinical implications.     

视网膜色素上皮损伤后相邻感光细胞及脉络膜血管的病理变化

目的:研究视网膜色素上皮(retinal pigment epithelium,RPE)损伤后相邻感光细胞和脉络膜血管的病理变化。方法:机械性刷除青紫蓝兔眼底髓线上方的RPE细胞,观察术后7,14,30d和90d清除区相邻感光细胞和脉络膜血管变化。结果:RPE细胞清除术后相邻的感光细胞发生退行性改变和死亡,脉络膜毛细血管萎缩。结论:RPE清除术可模拟萎缩型年龄相关性黄斑变性(age-related macular degeneration,AMD)及渗出型AMD剥膜以后的病理变化,为自体RPE移植挽救损伤的感光细胞的实验提供了良好的动物模型。     

Subretinal transplantation of bone marrow mesenchymal stem cells delays retinal degeneration in the RCS rat model of retinal degeneration

Because there is no effective treatment for this retinal degeneration, potential application of cell-based therapy has attracted considerable attention. Several investigations support that bone marrow mesenchymal stem cells (MSCs) can be used for a broad spectrum of indications. Bone marrow MSCs exert their therapeutic effect in part by secreting trophic factors to promote cell survival. The current study investigates whether bone marrow MSCs secrete factor(s) to promote photoreceptor cell survival and whether subretinal transplantation of bone marrow MSCs promotes photoreceptor survival in a retinal degeneration model using Royal College of Surgeons (RCS) rats. In vitro, using mouse retinal cell culture, it was demonstrated that the conditioned medium of the MSCs delays photoreceptor cell apoptosis, suggesting that the secreted factor(s) from the MSCs promote photoreceptor cell survival. In vivo, the MSCs were injected into the subretinal space of the RCS rats and histological analysis, real-time RT-PCR and electrophysiological analysis demonstrated that the subretinal transplantation of MSCs delays retinal degeneration and preserves retinal function in the RCS rats. These results suggest that MSC is a useful cell source for cell-replacement therapy for some forms of retinal degeneration.     

Multipotent retinal progenitors express developmental markers, differentiate into retinal neurons, and preserve light-mediated behavior

PURPOSE: To use progenitor cells isolated from the neural retina for transplantation studies in mice with retinal degeneration. METHODS: Retinal progenitor cells from postnatal day 1 green fluorescent protein-transgenic mice were isolated and characterized. These cells can be expanded greatly in culture and express markers characteristic of neural progenitor cells and/or retinal development. RESULTS: After they were grafted to the degenerating retina of mature mice, a subset of the retinal progenitor cells developed into mature neurons, including presumptive photoreceptors expressing recoverin, rhodopsin, or cone opsin. In rho-/- hosts, there was rescue of cells in the outer nuclear layer (ONL), along with widespread integration of donor cells into the inner retina, and recipient mice showed improved light-mediated behavior compared with control animals. CONCLUSIONS: These findings have implications for the treatment of retinal degeneration, in which neuronal replacement and photoreceptor rescue are major therapeutic goals.     

Cellular strategies for retinal repair by photoreceptor replacement

Loss of photoreceptors due to retinal degeneration is a major cause of blindness in the developed world. While no effective treatment is currently available, cell replacement therapy, using pluripotent stem cell-derived photoreceptor precursor cells, may be a feasible future treatment. Recent reports have demonstrated rescue of visual function following the transplantation of immature photoreceptors and we have seen major advances in our ability to generate transplantation-competent donor cells from stem cell sources. Moreover, we are beginning to realise the possibilities of using endogenous populations of cells from within the retina itself to mediate retinal repair. Here, we present a review of our current understanding of endogenous repair mechanisms together with recent progress in the use of both ocular and pluripotent stem cells for the treatment of photoreceptor loss. We consider how our understanding of retinal development has underpinned many of the recent major advances in translation and moved us closer to the goal of restoring vision by cellular means.