巨噬细胞极化在眼病发病机制中的作用

在多种眼部疾病的发生发展过程中,巨噬细胞及炎性因子介导的免疫反应是重要的发病机制.在微环境信号的作用下,巨噬细胞可极化为产生不同细胞因子、受体表达、效应功能的M1、M2型巨噬细胞,巨噬细胞具有多能性和异质性,其功能和表型可以在不同的微环境信号下动态转换,从而调节免疫炎症反应.巨噬细胞极化在角膜疾病、年龄相关性黄斑变性、糖尿病视网膜病变、自身免疫性葡萄膜炎的发病机制中也起到了重要的作用,其可塑性为其成为治疗靶点提供可能.     

角膜后弹力层剥除联合自动角膜刀取材内皮移植术的临床研究

目的 探讨角膜后弹力层剥除联合自动角膜刀取材内皮移植术的术后疗效、并发症、处理及适应证的选择.方法 临床病例系列研究.2007年9至12月期间,北京大学第三医院、北京大学眼科中心选择9例角膜内皮失代偿的患者行角膜后弹力层剥除自动角膜刀取材及角膜内皮移植手术,术后观察视力、角膜透明性的恢复、植片的脱位率、角膜厚度、角膜曲率及角膜内皮细胞数,随访时间3～7个月.结果 手术中1例虹膜角膜内皮综合征患者的角膜内皮植片植入失败,改行穿透性角膜移植术;其余8例患者术后植片明显脱位1例,再处理后复位.术后8例手术成功患者视力全部提高,植片透明,角膜厚度为(775±30)μm;角膜曲率为(44.19±2.28)D;角膜散光度数为(2.20±0.83)D;角膜内皮细胞数为(1439±296)个/mm~2.结论 角膜后弹力层剥除联合自动角膜刀取材内皮移植术有可能成为一种治疗角膜内皮失代偿的重要术式.     

角膜神经调控眼表微环境的研究进展

角膜是眼前段透明的外层结构，由高密度的神经组织支配。在角膜神经支配过程中，三叉神经节起源的角膜神经穿过上皮层和基质层中不同类型的角膜细胞。角膜基质细胞、上皮细胞、免疫细胞等多种细胞和角膜神经之间发生密切的相互作用，共同维持角膜微环境稳态。此外，角膜神经参与许多眼表疾病的发生发展过程。角膜神经释放多种活性肽物质，参与调控角膜感觉、维持上皮完整性和增殖、促进伤口愈合及调控角膜局部炎症和免疫反应等。本文对角膜神经在眼表微环境调控作用的研究进展进行综述，为角膜神经相关疾病的研究及治疗提供新的思路。     

角膜缘干细胞微环境的研究进展

角膜上皮的更新及损伤后修复有赖于角膜缘干细胞功能正常.角膜缘干细胞的增生及相关特性受干细胞微环境的调控影响.近年研究表明,角膜缘干细胞微环境包括干细胞龛三维结构、干细胞龛中存在的各种细胞类型、细胞分泌的细胞因子及角膜缘特异的基底膜.其中角膜缘细胞外基质和邻近细胞对角膜缘干细胞的调节尤为重要.模拟角膜缘干细胞微环境构建组织工程角膜对实现眼表重建,为患者带来复明希望具有重要意义.     

角膜内皮功能紊乱的易患因素

角膜内皮细胞密度是临床医师评估角膜内皮功能最常用的项目,但角膜内皮功能紊乱却没有得到相应的重视.近年来对各种眼部原发疾病、角膜移植术后等所致角膜内皮功能紊乱的临床数据有了更翔实的更新.眼部原发病中,各种类型的青光眼对角膜内皮的影响不尽相同,其中急性闭角型青光眼对角膜的损伤程度较慢性闭角型青光眼及开角型青光眼严重,青光眼不同的治疗方案对内皮的影响也各有特点.葡萄膜炎患者角膜内皮损伤的严重程度与炎症复发频数、炎症反应程度及病程密切相关.剥脱综合征患者前房含氧量低、细胞外纤维物质在眼前段的堆积、细胞发生纤维化改变等因素均可降低角膜内皮的功能,导致剥脱综合征患者角膜内皮细胞对损伤的耐受性差.对于角膜移植术后的患者,角膜移植排斥反应、手术方式、原发病、继发性晚期角膜内皮衰竭是角膜移植术后患者角膜内皮功能紊乱的重要因素.糖尿病是引起角膜内皮细胞储备能力下降的常见的全身性疾病,糖尿病患者细胞膜Na+/K+-ATP酶泵的功能降低、大量的晚期糖基化终产物的生成、代谢应激作用增强等因素均可降低角膜内皮创伤修复及愈合能力.本文就角膜内皮功能紊乱的易患因素进行综述,以帮助临床医师理解及重视该因素在内眼手术前的评估.     

中国角膜内皮移植术专家共识(2024年)

角膜内皮移植术是治疗角膜内皮疾病的重要方法, 主要分为角膜后弹力层剥除内皮移植术和角膜后弹力层内皮移植术。与穿透性角膜移植术比较, 角膜内皮移植术的术后视力好, 免疫排斥反应发生率低, 但手术技术和过程较为复杂, 术中和术后并发症有所不同。角膜内皮移植术的成功关键在于掌握手术的基本要素并预防并发症。为在我国规范开展和推广角膜内皮移植术, 中华医学会眼科学分会角膜病学组以国内外研究结果和临床实践经验为基础, 围绕角膜内皮移植术的适应证、术前评估、手术技术和操作、术后并发症处理和随访等进行充分讨论, 达成共识性意见, 以期为临床工作提供指导和参考。     

角膜内皮细胞移植的手术进展

角膜内皮细胞层的完整和功能健全是维持角膜透明的重要因素。角膜内皮失代偿将导致角膜浑浊,严重影响视力。近年来兴起的角膜成分移植的优越性已经逐渐得到大家的公认,其中角膜内皮移植手术选择性的替代受损的角膜内层组织,具有术后视力恢复快,散光小等优点,已经得到广泛应用。现主要就角膜内皮移植手术的发展过程,优点及术后早期并发症等进行综述。     

角膜后弹力层内皮移植术的研究进展

十年间角膜内皮移植术已在我国各级医院广泛开展,并取得了显著成绩。而角膜后弹力层内皮移植术作为角膜内皮移植术中治疗角膜内皮病变的理想术式,在国内仅有少数医院进行了初步尝试。本文从手术适应证、手术过程及术后并发症等方面综述角膜后弹力层内皮移植术在国内外的发展现状,以期为该手术在国内广泛开展提供参考。（中华眼科杂志,2015,51：544-547）     

角膜碱烧伤的免疫学机制研究进展

角膜碱烧伤是眼科临床常见的致盲性眼病,一旦发生,治疗相当棘手,预后极差,其损伤机制的研究一直受到众多学者的重视。许多研究表明,角膜碱烧伤后免疫系统的参与起着非常重要的作用。角膜碱烧伤后角膜免疫微环境的变化致使各种效应细胞和炎性细胞出现规律性变化,另外各种炎性因子也参与角膜碱烧伤的病理损伤过程。就角膜碱烧伤的免疫学机制进行综述。     

无缝线深板层角膜内皮移植术的研究进展

角膜内皮失代偿可严重影响视力,以往多采用的穿透性角膜移植手术(PKP)具有术后高度散光、移植片排斥等并发症,严重限制了术后视力的提高.如果能够单纯地进行后弹力层和内皮细胞层的移植,将减少手术操作所带来的受体角膜损伤并能更好地恢复术后视力.近年来,无缝线深板层角膜内皮移植手术的优点已逐渐获得公认;其中深板层角膜内皮细胞移植手术(DLEK)手术难度较大,限制了其在临床的广泛开展.而通过剥除受体角膜的后弹力层和内皮层来制作植床的角膜内皮移植手术即角膜后弹力层剥除内皮细胞移植手术(DSEK)已经取得了较好的手术效果.本文归纳、分析了DSEK的手术方法、效果及并发症等.     

Research progress on the negative factors of corneal endothelial cells proliferation

The human corneal endothelium forms a boundary layer between anterior chamber and corneal stoma. The corneal endothelial cells are responsible for maintaining cornea transparency, which is very vital for our visual acuity, via its pump and barrier functions. The adult corneal endothelial cells in vivo lack proliferation in response to the cell loss caused by outer damages and diseases. As a result, in order to compensate for cell loss, corneal endothelial cells migrate and enlarge while not via dividing to increase the endothelial cell density. Therefore, it is not capable for corneal endothelium to restore the corneal clarity. Some researches have proved that in vitro the corneal endothelial maintained proliferation ability. This review describes the current research progress regarding the negative factors that inhibit proliferation of the corneal endothelial cells. This review will mainly present several genes and proteins that inhibit the proliferation of the corneal endothelial cells, of course including some other factors like enzymes and position.     

Glaucoma-associated corneal endothelial cell damage: A review

The corneal endothelium is critical in maintaining a healthy and clear cornea. Corneal endothelial cells have a significant reserve function, but preservation of these cells is paramount as they have limited regenerative capacity. Glaucoma is a prevalent disease, and damage to the corneal endothelium may be caused by the disease process itself as well as by its treatment. The mechanisms involved in glaucoma-associated damage to the corneal endothelium need further investigation. Understanding how glaucoma and glaucoma surgery impact the endothelium is important for protecting corneal clarity and visual acuity in all glaucoma patients, including those undergoing corneal transplant. We will discuss a range of identified factors that may impact corneal endothelial cell health in glaucoma, including intraocular pressure, glaucoma medications, surgical glaucoma management, mechanical forces, and alterations in the aqueous environment.     

Proliferative capacity of the corneal endothelium

Corneal endothelium is the single layer of cells forming a boundary between the corneal stroma and anterior chamber. The barrier and "pump" functions of the endothelium are responsible for maintaining corneal transparency by regulating stromal hydration. Morphological studies have demonstrated an age-related decrease in endothelial cell density and indicate that the endothelium in vivo either does not proliferate at all or proliferates at a rate that does not keep pace with the rate of cell loss. Lack of a robust proliferative response to cell loss makes the endothelium, at best, a fragile tissue. As a result of excessive cell loss due to accidental or surgical trauma, dystrophy, or disease, the endothelium may no longer effectively act as a barrier to fluid flow from the aqueous humor to the stroma. This loss of function can cause corneal edema, decreased corneal clarity, and loss of visual acuity, thus requiring corneal transplantation to restore normal vision. Studies from this and other laboratories indicate that corneal endothelium in vivo DOES possess proliferative capacity, but is arrested in G1-phase of the cell cycle. It appears that several intrinsic and extrinsic factors together contribute to maintain the endothelium in a non-replicative state. Ex vivo studies comparing cell cycle kinetics in wounded endothelium of young (< 30 years old) and older donors ( > 50 years old) provide evidence that cells from older donors can enter and complete the cell cycle; however, the length of G1-phase appears to be longer and the cells require stronger mitogenic stimulation than cells from younger donors. In vivo conditions per se also contribute to maintenance of a non-replicative monolayer. Endothelial cells are apparently unable to respond to autocrine or paracrine stimulation even though they express mRNA and protein for a number of growth factors and their receptors. Exogenous transforming growth factor-beta (TGF-beta) and TGF-beta in aqueous humor suppress S-phase entry in cultured endothelial cells, suggesting that this cytokine could inhibit proliferation in vivo. In addition, cell-cell contact appears to inhibit endothelial cell proliferation during corneal development and to help maintain the mature endothelial monolayer in a non-proliferative state, in part, via the activity of p27kip1, a known G1-phase inhibitor. The fact that human corneal endothelium retains proliferative capacity has led to recent efforts to induce division and increase the density of these important cells. For example, recent studies have demonstrated that adult human corneal endothelial cells can be induced to grow in culture and then transplanted to recipient corneas ex vivo. The laboratory work that has been conducted up to now opens an exciting new door to the future. The time is right to apply the knowledge that has been gained regarding corneal endothelial cell proliferative capacity and regulation of its cell cycle to develop new therapies to treat patients at risk for vision loss due to low endothelial cells counts.     

各种因素对角膜内皮细胞形态的影响

角膜内皮细胞的研究早在19世纪就开始了,近年来各种新设备和技术的应用使人们对角膜内皮损伤的进一步研究成为可能,对角膜内皮损伤的病理、愈合的过程、修复机制也有了更深刻的认识。很多疾病、手术、外伤、药物、激光以及先天性疾病等都可以对角膜细胞产生很大的影响。它们可以引起角膜内皮细胞水肿、细胞数量减少、多形性变化。     

Molecular bases of corneal endothelial dystrophies

The phrase "corneal endothelial dystrophies" embraces a group of bilateral corneal conditions that are characterized by a non-inflammatory and progressive degradation of corneal endothelium. Corneal endothelial cells exhibit a high pump site density and, along with barrier function, are responsible for maintaining the cornea in its natural state of relative dehydration. Gradual loss of endothelial cells leads to an insufficient water outflow, resulting in corneal edema and loss of vision. Since the pathologic mechanisms remain largely unknown, the only current treatment option is surgical transplantation when vision is severely impaired. In the past decade, important steps have been taken to understand how endothelial degeneration progresses on the molecular level. Studies of affected multigenerational families and sporadic cases identified genes and chromosomal loci, and revealed either Mendelian or complex disorder inheritance patterns. Mutations have been detected in genes that carry important structural, metabolic, cytoprotective, and regulatory functions in corneal endothelium. In addition to genetic predisposition, environmental factors like oxidative stress were found to be involved in the pathogenesis of endotheliopathies. This review summarizes and crosslinks the recent progress on deciphering the molecular bases of corneal endothelial dystrophies.     

HLA antigenicity of normal and pathological corneas

Fresh human corneas and corneal buttons were studied for expression of HLA antigens. Using monoclonal antibodies in an indirect immunofluorescence assay, corneal layers were examined for class I (HLA-A, B, C) and class II (HLA-DR) histocompatibility antigens. Twenty-one human corneas were studied, 6 normal and 15 pathological: 4 buttons of allograft rejection, 9 buttons of pseudophakic bullous keratopathy. In fresh control corneas, HLA-A, B, C antigens were localized on corneal epithelium and on stromal keratocytes but were never found on endothelial cells. HLA-DR antigens were not detected on corneal epithelium, stroma or endothelium but were detected on Langerhans cells within epithelium and anterior stroma. At the corneal limbus, HLA class I-II antigens were expressed on vascular endothelium. HLA antigen distribution was modified in pathological corneas. Antigens HLA-A, B, C were induced on endothelial cells of rejected corneal allografts. Antigens HLA-DR were detected on epithelial cells, cells in the stroma of pseudophakic bullous keratopathy and also on endothelial cells of rejected corneal allografts. These results suggest that induction of class I and II antigen expression by inflammatory factors may occur in vivo. In rejected corneal allografts induction of HLA-DR antigen on corneal layers would intensify the process of rejection. This study and others have demonstrated the ability of modulation of HLA antigen expression on human corneal cells in vivo.     

Endothelial cell transplantation and growth behavior of the human corneal endothelium

Background: The human corneal endothelium has a limited proliferative capacity in vivo. Until now it has only been possible to replace damaged endothelium by transplantation of a donor cornea. After establishing methods for the isolation and in vitro cultivation of human corneal endothelial cells, transplantation of these cells my be an alternative therapeutic option. Materials and methods: In this review methods for the in vitro cultivation of human corneal endothelial cells and their transplantation on the Descemet membrane of donor corneas are described. Results: In vitro proliferation of human adult corneal endothelial cells was achieved by the development of defined cell culture conditions, including supplementation of culture medium with specified growth factors and substances. Dependent on the culture conditions, as well as independent of them, in vitro cultured endothelial cells showed phenotypic changes and different proliferative behavior. Thus, molecular biological examinations revealed a different expression pattern of growth factor receptors in fibroblast-like endothelial cells (dedifferentiated) compared to typical endothelial cells (differentiated). Moreover, the proliferative capacity of the cells differed, dependent on their corneal location. Cells isolated from the peripheral part of donor corneas have a higher proliferative capacity than cells obtained from the central part. The propagation of corneal endothelial cells in vitro offered the possibility of their transplantation on donor corneas in an in vitro model. After transplantation, these cells formed a monolayer whose morphology and cell density depended on the differentiation of the cells. DNA synthesis was predominantly detectable in cells of the corneal periphery. Conclusions: Our findings are the basis of the following hypothesis: the periphery of the cornea represents a regenerative zone of the corneal endothelium. The fact that early after transplantation corneal endothelial cells form a monolayer on the natural extracellular matrix (ECM), which shows contact inhibition, suggests that inhibitory factors are released by the Descemet membrane that influence the proliferation of the cells. Further studies on the regulation of the proliferation and differentiation of human corneal endothelial cells in vitro and after transplantation might offer the possibility to establish a selective procedure for the treatment of corneal endothelial cell loss in the near future.      

Prospects for endothelial transplantation

BACKGROUND: The human corneal endothelium has a limited proliferative capacity in vivo. Until now it has only been possible to replace damaged endothelium by transplantation of a donor cornea. After establishing methods for the isolation and in vitro cultivation of human corneal endothelial cells (HCEC), transplantation of these cells may be an alternative therapeutic option. MATERIALS AND METHODS: In this review methods for the in vitro cultivation of HCEC and their transplantation onto the Descemet membrane of donor corneas are described. RESULTS: In vitro proliferation of human adult corneal endothelial cells was achieved by the development of defined cell culture conditions, including supplementation of culture medium with specified growth factors. Dependent on the culture conditions, in vitro cultured endothelial cells showed phenotypic changes and different proliferative behaviour. The propagation of corneal endothelial cells in vitro offered the possibility of their transplantation onto donor corneas in an in vitro model. After transplantation, these cells formed a monolayer whose morphology and cell density depended on the differentiation status of the cells in vitro. Highest cell numbers up to 3000 cells/mm2 were achieved using a SV40-transformed HCEC-cell line. Monolayer integrity could be demonstrated by positive staining for integrins and light junction proteins, and pump function of the newly established endothelium was proven by perfusion studies. CONCLUSIONS: Methods to transplant HCEC onto human denuded corneas have been successfully established to reconstruct human corneas. Recent developments in genetic manipulation of cells and tissue engineering will be of great help in constructing suitable corneas for keratoplasty. Thus corneal endothelial cell transplantation is one of the promising future possibilities to provide corneas of high quality for patients. Furthermore, improvement of the transplantation technique may lead to a method to directly manipulate the diseased endothelium of patients with corneal endothelial dystrophies.     

Human corneal endothelial cells: isolation, characterization and long-term cultivation

Long-term cultures of human corneal endothelial cells have been established. In culture, these cells form a dense monolayer (about 500,000 cells cm-2), similar to that found in vivo, and synthesize an extracellular matrix containing laminin, entactin, and fibronectin. Factor VIII and angiotensin-converting enzyme were not found in either the cultured or native corneal endothelium. Cells were obtained by scraping corneal buttons that had been preincubated in the culture medium supplemented with endothelial cell mitogen. The human corneal endothelium was grown under conditions virtually the same as those used for cultivation of human vascular endothelial cells, namely, on fibronectin- or gelatin-coated tissue culture plastic in Medium 199 supplemented with 20% human serum and 400 micrograms ml-1 endothelial cell growth supplement. Human corneal endothelial cells from the culture obtained can be used for transplantation onto human corneas, for studying repair of damaged corneal endothelium in situ, as well as for in vitro studies of cell growth regulation.     

角膜内皮细胞移植

角膜内皮细胞在体外培养的条件下可以在同种异体或异种角膜后弹力层上成功生长,培养的上皮细胞的生长情况及特性与供体年龄、内皮细胞来源部位、载体材料、培养条件、以及是否应用生长因子有密切关系。人角膜内皮细胞培养的成功,以及在非人类的灵长目动物眼上的成功移植,为内皮移植技术的治疗作用提供了实验基础。培养传代的角膜内皮细胞移植到活体上后具有正常内皮细胞的功能,可以作为穿透性角膜移植的替代方法之一加以选择。