干细胞治疗青光眼的研究进展

青光眼是一类不可逆性视神经变性和视野缺损的疾病,青光眼导致视神经损伤的机制目前尚未明确,临床上对青光眼的治疗一直未取得良好的效果.干细胞具有自我增殖和分化的能力.近年来随着对干细胞研究的深入,人类利用干细胞治疗青光眼成为可能.青光眼干细胞移植分两大类:一是基于小梁网的干细胞替代治疗,另一类是视网膜神经节细胞的替代治疗.本文就干细胞治疗青光眼的研究进展进行综述.     

Neuronal death in glaucoma

Glaucoma is recognized to have its major detrimental effect upon the eye by killing retinal ganglion cells. The process of cell death appears to be initiated at the optic nerve head, though other sites of injury are possible but unsubstantiated. At present the injury at the nerve head seems related to the level of the eye pressure, but its detailed mechanism is as yet unexplained. There is a greater loss of ganglion cells from some areas of the eye, and this feature of glaucoma seems related to the regional structure of the supporting connective tissues of the optic nerve head. Larger retinal ganglion cells have been consistently shown to have somewhat greater susceptibility to injury in glaucoma, though all cells are injured, even early in the process. Ganglion cells die by apoptosis in human and experimental glaucoma, opening several potential areas for future therapies to protect them from dying. Neurotrophin deprivation is one possible cause of cell death and replacement therapy is a potential approach to treatment.     

原发性青光眼视神经损害的发生机制

关于原发性青光眼的发病机制,目前有许多学说,但每种学说都不能完全说明青光眼视神经损害的具体机制。综合分析发现,每个正常人或青光眼患者身上都具有致视神经损害因素和抗视神经损害因素,青光眼发生与否是这两种因素相斗争的结果。眼压虽然不是青光眼视神经损害的唯一因素,但仍然是青光眼最主要和最稳定的危险因素。另外,血循环因素和免疫因素也是导致青光眼视神经损害的重要原因。本文综合分析了近年来有关原发性青光眼视神经损害机制的研究,并以独特的视角分析了眼压对青光眼视神经损害的具体机制。     

TLR4在青光眼视神经损伤机制中的作用

青光眼是一种以视乳头萎缩凹陷、视野缺损及视力下降为共同特征的不可逆的致盲性疾病,其视神经损伤的本质为视神经节细胞的凋亡。尽管通过药物干预和手术控制眼压可以对青光眼起到一定的治疗作用,但如何从根本上阻止青光眼的进一步发展仍处于探索阶段。因此,研究青光眼视神经损伤机制,通过阻断视神经损伤而治疗青光眼至关重要。近几年,免疫机制对青光眼视神经损伤的影响成为研究热点,本文中主要对Toll样受体4(TLR4)通过不同免疫通路并与神经胶质细胞相互作用引起青光眼患者视神经损伤进行综述。     

巩膜生物力学改变与青光眼性视神经损伤

青光眼的主要病理特征是视网膜神经节细胞(RGC)的丧失,从而导致进行性、不可逆性的视力丧失。目前已有研究表明,巩膜的生物力学性质会影响视神经的生物力学变化,并且在RGC损伤和视力丧失的病理过程中起重要作用。因此,巩膜生物力学与青光眼关系的研究对深入了解青光眼的发病机制有着重要的意义。本文就巩膜的生物力学特性、巩膜胶原纤维结构、巩膜重塑、巩膜刚度及通透性与青光眼性视神经损伤的关系进行综述,以利于更深入地了解青光眼性视神经损害的机制,为青光眼的预防和治疗提供新思路。     

青光眼视神经损伤与修复期待精准的个体化治疗

青光眼是临床上常见的以视神经损害为主要特征的致盲眼病,降低眼压仍是目前治疗青光眼的主要方法,但一些患者眼压虽然得到合理控制,视神经损害却难以恢复,甚至持续发展,因此其病理机制的研究和视神经损害的防治研究一直是近年来青光眼治疗研究的热点.最近随着生物医学研究的快速发展,尽管青光眼视神经损伤和修复的基础研究已经取得了显著进展,青光眼视神经损伤的机制已得到阐明,但是鲜见证据充分的、有确定疗效的临床研究报道.目前基因组学研究、干细胞研究、分子生物学研究、电子技术在医学中的应用研究等取得了长足进步,尤其是大数据时代的到来更为临床上青光眼的神经保护研究奠定了良好的基础.眼科医生应关注大数据信息时代为疾病精准化治疗带来的机遇和挑战,聚焦于青光眼视神经保护的精准个体化治疗,降低青光眼的致盲率.     

Axonal loss from acute optic neuropathy documented by scanning laser polarimetry

BACKGROUND/AIMS: Retinal nerve fibre layer analysis by scanning laser polarimetry has been shown to facilitate diagnosis of glaucoma while its role in glaucoma follow up is still unclear. A major difficulty is the slow reduction of retinal nerve fibre layer thickness in glaucomatous optic neuropathy. Eyes of patients were studied after acute retrobulbar optic nerve lesion in order to evaluate the usefulness of scanning laser polarimetry in documenting retinal nerve fibre layer loss over time. METHODS: Five patients who suffered severe retrobulbar optic neuropathy have had repeated measurements of the retinal nerve fibre layer using scanning laser polarimetry at various intervals, the first examination being within 1 week of injury. RESULTS: All eyes showed a marked decrease in peripapillary retinal nerve fibre layer thickness, which followed an exponential curve and occurred predominantly within 8 weeks of injury. Compared to a previous study using red-free photographs, scanning laser polarimetry showed retinal nerve fibre layer loss earlier in the course of descending atrophy. CONCLUSION: Scanning laser polarimetry is useful for early detection and documentation of retinal nerve fibre layer loss following acute injury to the retrobulbar optic nerve. It seems to be a promising tool for follow up of individual glaucoma patients.     

青光眼视神经保护的研究进展

视网膜神经节细胞死亡是青光眼视神经损伤的最终共同通路,阻断视神经损伤通路和增强视神经存活机制的方法称为视神经保护。目前这一研究领域主要包括抗凋亡途径,促红细胞生成素,谷氨酸拮抗剂,钙离子拮抗剂,一氧化氮合酶抑制剂,神经营养因子,自身保护性免疫,抗青光眼药物等方面。将来视神经保护将成为一种重要的青光眼辅助治疗措施     

Mesenchymal stem cells for repairing glaucomatous optic nerve

Glaucoma is a common and complex neurodegenerative disease characterized by progressive loss of retinal ganglion cells (RGCs) and axons. Currently, there is no effective method to address the cause of RGCs degeneration. However, studies on neuroprotective strategies for optic neuropathy have increased in recent years. Cell replacement and neuroprotection are major strategies for treating glaucoma and optic neuropathy. Regenerative medicine research into the repair of optic nerve damage using stem cells has received considerable attention. Stem cells possess the potential for multidirectional differentiation abilities and are capable of producing RGC-friendly microenvironments through paracrine effects. This article reviews a thorough researches of recent advances and approaches in stem cell repair of optic nerve injury, raising the controversies and unresolved issues surrounding the future of stem cells.     

Biomechanics of the sclera and effects on intraocular pressure

Accumulating evidence indicates that glaucoma is a multifactorial neurodegenerative disease characterized by the loss of retinal ganglion cells (RGC), resulting in gradual and progressive permanent loss of vision. Reducing intraocular pressure (IOP) remains the only proven method for preventing and delaying the progression of glaucomatous visual impairment. However, the specific role of IOP in optic nerve injury remains controversial, and little is known about the biomechanical mechanism by which elevated IOP leads to the loss of RGC. Published studies suggest that the biomechanical properties of the sclera and scleral lamina cribrosa determine the biomechanical changes of optic nerve head, and play an important role in the pathologic process of loss of RGC and optic nerve damage. This review focuses on the current understanding of biomechanics of sclera in glaucoma and provides an overview of the possible interactions between the sclera and IOP. Treatments and interventions aimed at the sclera are also discussed.     

The effect of experimental glaucoma and optic nerve transection on amacrine cells in the rat retina

PURPOSE: To detect alterations in amacrine cells associated with retinal ganglion cell (RGC) depletion caused by experimental optic nerve transection and glaucoma. METHODS: Intraocular pressure (IOP) was elevated unilaterally in 18 rats by translimbal trabecular laser treatment, and eyes were studied at 1 (n = 6), 2 (n = 5), and 3 (n = 7) months. Complete optic nerve transection was performed unilaterally in nine rats with survival for 1 (n = 4) and 3 (n = 5) months. Serial cryosections (five per eye) were immunohistochemically labeled with rabbit anti-gamma-aminobutyric acid (GABA) and anti-glycine antibodies. Cells in the ganglion cell and inner nuclear layers that labeled for GABA or glycine were counted in a masked fashion under bright-field microscopy. Additional labeling with other RGC and amacrine antigens was also performed. RGC loss was quantified by axon counts. RESULTS: Amacrine cells identified by GABA and glycine labeling were not significantly affected by experimental glaucoma, with a mean decrease of 15% compared with bilaterally untreated control cells (557 +/- 186 neurons/mm [glaucoma] versus 653.9 +/- 114.4 neurons/mm [control] of retina; P = 0.15, t-test). There was no significant trend for amacrine cell counts to be lower in eyes with fewer RGCs (r = -0.39, P = 0.11). By contrast, there was highly significant loss of GABA and glycine staining 3 months after nerve transection, both in the treated and the fellow eyes (P < 0.0001, t-test). However, there was a substantial number of remaining amacrine cells in transected retinas, as indicated by labeling for calretinin and calbindin. CONCLUSIONS: Experimental glaucoma causes minimal change in amacrine cells and their expression of neurotransmitters. After nerve transection, neurotransmitter presence declines, but many amacrine cell bodies remain. Differences among optic nerve injury models, as well as effects on "untreated" fellow eyes, should be recognized.     

青光眼的视觉通路损伤及损伤后视觉系统的神经可塑性研究进展

青光眼是一组以进行性视神经萎缩和视野缺损为共同特征的疾病。近来研究表明青光眼的病理损伤不仅局限于视网膜及视神经,而是累及整个视觉通路。近年研究发现神经系统损伤并非传统认为的完全不可逆,而是具有一定的可塑性,也有研究表明青光眼的视觉通路的神经元在一定条件刺激下,可能进行修复及重塑,从而恢复一定的视觉功能,这为青光眼的治疗提供了新的思路及方向。     

The molecular basis of retinal ganglion cell death in glaucoma

Glaucoma is a group of diseases characterized by progressive optic nerve degeneration that results in visual field loss and irreversible blindness. A crucial element in the pathophysiology of all forms of glaucoma is the death of retinal ganglion cells (RGCs), a population of CNS neurons with their soma in the inner retina and axons in the optic nerve. Strategies that delay or halt RGC loss have been recognized as potentially beneficial to preserve vision in glaucoma; however, the success of these approaches depends on an in-depth understanding of the mechanisms that lead to RGC dysfunction and death. In recent years, there has been an exponential increase in valuable information regarding the molecular basis of RGC death stemming from animal models of acute and chronic optic nerve injury as well as experimental glaucoma. The emerging landscape is complex and points at a variety of molecular signals - acting alone or in cooperation - to promote RGC death. These include: axonal transport failure, neurotrophic factor deprivation, toxic pro-neurotrophins, activation of intrinsic and extrinsic apoptotic signals, mitochondrial dysfunction, excitotoxic damage, oxidative stress, misbehaving reactive glia and loss of synaptic connectivity. Collectively, this body of work has considerably updated and expanded our view of how RGCs might die in glaucoma and has revealed novel, potential targets for neuroprotection.     

青光眼与颈动脉相关性研究进展

青光眼是一种进行性特征性视神经损害为共同特征的眼部疾病.在以往的研究中高眼压被认为是导致视神经损害的主要危险因素.其中颈动脉狭窄所致眼部血流调节异常及视神经血流灌注不足导致的缺血缺氧也是青光眼视神经损伤的重要发病机制之一.研究发现颈动脉异常在青光眼的发生、发展中起着十分重要作用.本文就青光眼与颈动脉的相关性研究进行综述.     

The histology of human glaucoma cupping and optic nerve damage: clinicopathologic correlation in 21 eyes

We have examined by light and electron microscopy the retina, optic nervehead, and optic nerves of 21 human eyes from glaucoma patients in whom clinical information was available for comparison. In several cases it was possible to correlate the degree and distribution of optic nerve damage with the clinical appearance of the optic disc and visual field studies. There was no selective loss of astrocytes of the optic nervehead in early glaucoma cupping. Acquired increases in optic disc cup size prior to detectable visual field loss probably represent loss of ganglion cell axonal fibers which is not yet significant enough to produce field defects. It is unlikely that the mechanism of axonal damage in chronic human glaucoma involves early loss of astrocytic glial cells at the optic nervehead. At the level of the retrobulbar optic nerve, the ganglion cell axonal fibers of the superior and inferior quadrants seem to be lost earlier than the fibers of the nasal and temporal nerve periphery. Since the superior and inferior poles of the optic nerve may contain the fibers of arcuate area ganglion cells, these data confirm the presumption from visual field testing that arcuate area ganglion cell fibers are selectively more susceptible to damage in chronic glaucoma.     

Linking structure and function in glaucoma

The glaucomas are a group of relatively common optic neuropathies, in which the pathological loss of retinal ganglion cells causes a progressive loss of sight and associated alterations in the retinal nerve fiber layer and optic nerve head. The diagnosis and management of glaucoma are often dependent on methods of clinical testing that either, 1) identify and quantify patterns of functional visual abnormality, or 2) quantify structural abnormality in the retinal nerve fiber layer, both of which are caused by loss of retinal ganglion cells. Although it is evident that the abnormalities in structure and function should be correlated, propositions to link losses in structure and function in glaucoma have been formulated only recently. The present report describes an attempt to build a model of these linking propositions using data from investigations of the relationships between losses of visual sensitivity and thinning of retinal nerve fiber layer over progressive stages of glaucoma severity. A foundation for the model was laid through the pointwise relationships between visual sensitivities (behavioral perimetry in monkeys with experimental glaucoma) and histological analyses of retinal ganglion cell densities in corresponding retinal locations. The subsequent blocks of the model were constructed from clinical studies of aging in normal human subjects and of clinical glaucoma in patients to provide a direct comparison of the results from standard clinical perimetry and optical coherence tomography. The final formulation is a nonlinear structure–function model that was evaluated by the accuracy and precision of translating visual sensitivities in a region of the visual field to produce a predicted thickness of the retinal nerve fiber layer in the peripapillary sector that corresponded to the region of reduced visual sensitivity. The model was tested on two independent patient populations, with results that confirmed the predictive relationship between the retinal nerve fiber layer thickness and visual sensitivities from clinical perimetry. Thus, the proposed model for linking structure and function in glaucoma has provided information that is important in understanding the results of standard clinical testing and the neuronal losses caused by glaucoma, which may have clinical application for inter-test comparisons of the stage of disease.     

Glaucoma as primary optic neuropathy

The appearance of the new concept of glaucomatous optic neuropathy directed to idea that high intraocular pressure and vascular insufficiency in the optic nerve head are only risk factors in the appearance of glaucoma. Glaucomatous optic neuropathy is the consequence of progressive loss of the retinal ganglion cells whose axons comprise the optic nerve. A great number of neurotrophic agents are under investigation with the view of preventing the dead of retinal ganglion cells. Induction of cell rescue mechanisms may be an alternate and efficient strategy for neuroprotection. The paper presents both actual data about the pathophysiological mechanisms of glaucoma (neurotrophin deprivation, excitotoxicity caused by glutamate, "ischemic cascade", apoptosis of retinal ganglion cells) and neuroprotective and neuroregenerative therapy and antiapoptotic agents.     

The optic nerve head in glaucoma: role of astrocytes in tissue remodeling

Primary open angle glaucoma is a common eye disease characterized by loss of the axons of the retinal ganglion cells leading to progressive loss of vision. The site of damage to the axons is at the level of the lamina cribrosa in the optic nerve head. The mechanism of axonal loss is unknown but elevated intraocular pressure and age are the most common factors associated with the disease. Previous studies in human glaucoma and in experimental glaucoma in monkeys have established a relationship between chronic elevation of intraocular pressure and remodeling of the optic nerve head tissues known clinically as cupping of the optic disc. This review focuses on the astrocytes, the major cell type in the optic nerve head. Astrocytes participate actively in the remodeling of neural tissues during development and in disease. In glaucomatous optic neuropathy, astrocytes play a major role in the remodeling of the extracellular matrix of the optic nerve head, synthesize growth factors and other cellular mediators that may affect directly, or indirectly, the axons of the retinal ganglion cells. Due to the architecture of the lamina cribrosa, formed by the cells and the fibroelastic extracellular matrix, astrocytes may respond to changes in intraocular pressure in glaucoma, leading to some of the detrimental events that underlie axonal loss and retinal ganglion cell degeneration.     

青光眼视神经保护治疗的研究进展

青光眼是由于眼压升高引起视乳头损害和视野缺损的一种致盲性眼病,其病理基础是视网膜神经节细胞及其轴突的进行性丢失。过去大量的研究都集中在降低眼压方面,现在视神经保护治疗作为一种通过阻止神经元死亡治疗青光眼的新策略已被普遍接受。我们从NMDA受体拮抗剂、神经营养因子、热休克蛋白、免疫系统等方面,总结了目前青光眼视神经保护治疗的研究进展。