There is accumulating evidence that autoimmune components, such as autoantibodies and autoantibody depositions, play a role in the pathogenesis of neurodegenerative diseases like Alzheimeŕs disease or Multiple Sclerosis. Due to alterations of autoantibody patterns in sera and aqueous humor, an autoimmune component is also assumed in the pathogenesis of glaucoma, a common reason for irreversible blindness worldwide. So far there has been no convincing evidence that autoantibodies are accumulated in the retina of glaucoma patients and that the local immune homeostasis might be affected. Six human glaucomatous donor eyes and nine samples from donors with no recorded ocular disease were included. Antibody microarrays were used to examine the patterns of pro-inflammatory proteins and complement proteins. Analysis of TNF-α and interleukin levels revealed a slight up-regulation exclusively in the glaucomatous group, while complement protein levels were not altered. IgG autoantibody accumulations and/or cellular components were determined by immunohistology (n = 4 per group). A significantly reduced number of retinal ganglion cells was found in the glaucomatous group (healthy: 104±7 nuclei/mm, glaucoma: 67±9 nuclei/mm; p = 0.0007). Cell loss was accompanied by strong retinal IgG autoantibody accumulations, which were at least twice as high as in healthy subjects (healthy: 5.0±0.5 IgG deposits/100 cells, glaucoma: 9.4±1.9 IgG deposits/100 cells; p = 0.004). CD27⁺ cells and CD27⁺/IgG⁺ plasma cells were observed in all glaucomatous subjects, but not in controls. This work provides serious evidence for the occurrence of IgG antibody deposition and plasma cells in human glaucomatous retina. Moreover, the results suggest that these IgG deposits occurred in a pro-inflammatory environment which seems to be maintained locally by immune-competent cells like microglia. Thereby, glaucoma features an immunological involvement comparable to other neurodegenerative diseases, but also shows a multifactorial pathomechanism, which diverges and might be linked to the specific nature of both eye and retina.

Significance: The regulation of intraocular pressure (IOP) is vital for the health of the eye. Failure to maintain IOP frequently leads to vision loss in glaucoma. The IOP is maintained by the trabecular meshwork (TM), which exhibits decreased cellular density with age and disease. Here we demonstrate that induced pluripotent stem cells differentiated into TM cells (designated iPSC-TM) restore TM function for over 9 wk, regulate IOP, and prevent neuronal loss in a glaucoma mouse model. Transplanted iPSC-TM survive in the TM, but the most pronounced effect of transplantation is a robust proliferative response of endogenous TM cells. These findings suggest that lasting restoration of IOP control through iPSC-TM transplantation is possible and may represent a novel treatment approach for glaucoma.

Purpose: Primary open-angle glaucoma (POAG) is particularly common in older individuals and associated with pathologic degeneration of the trabecular meshwork (TM). We have shown previously that transplantation of induced pluripotent stem cell (iPSC) derived TM cells restores aqueous humor dynamics in young transgenic mice expressing a pathogenic form of human myocilin (Tg-MYOC^Y437H). This study was designed to determine if this approach is feasible in older mice with more pronounced TM dysfunction. Methods: Mouse iPSC were differentiated toward a TM cell phenotype (iPSC-TM) and injected into the anterior chamber of 6-month-old Tg-MYOC^Y437H or control mice. IOP and aqueous humor outflow facility were recorded for up to 3 months. Transmission electron microscopy, Western blot, and immunohistochemistry were performed to analyze TM morphology, quantify endoplasmic reticulum (ER) stress, and assess TM cellularity. Results: A 12 weeks after transplantation, IOP in iPSC-TM recipients was statistically lower and outflow facility was significantly improved compared to untreated controls. The number of endogenous TM cells increased significantly in iPSC-TM recipients along with the appearance of TM cells immmunopositive for a marker of cellular division. Morphologically, transplantation of iPSC-TM preserves ER structure 12 weeks after transplantation. However, myocilin and calnexin expression levels remain elevated in transplanted eyes of these 9-month-old Tg-MYOC^Y437H mice, indicating that ER stress persists within the TM. Conclusions: Transplantation of iPSC-TM can restore IOP and outflow facility in aged Tg-MYOC^Y437H mice. This type of stem cell–based therapy is a promising possibility for restoration of IOP control in some glaucoma patients.

Antibodies against retinal and optic nerve antigens are detectable in glaucoma patients. Recent studies using a model of experimental autoimmune glaucoma demonstrated that immunization with certain ocular antigens causes an immun-mediated retinal ganglion cell loss in rats. Rats immunized with a retinal ganglion cell layer homogenate (RGA) had a reduced retinal ganglion cell density on retinal flatmounts (p = 0.007) and a lower number of Brn3⁺retinal ganglion cells (p = 0.0001) after six weeks. The autoreactive antibody development against retina and optic nerve was examined throughout the study. The levels of autoreactive antibodies continuously increased up to 6 weeks (retina: p = 0.004; optic nerve: p = 0.000003). Additionally, antibody deposits were detected in the retina (p = 0.02). After 6 weeks a reactive gliosis (GFAP density: RGA: 174.7±41.9; CO: 137.6±36.8, p = 0.0006; %GFAP⁺ area: RGA: 8.5±3.4; CO: 5.9±3.6, p = 0.006) as well as elevated level of Iba1⁺ microglia cells (p = 0.003) was observed in retinas of RGA animals. Our findings suggest that these antibodies play a substantial role in mechanisms leading to retinal ganglion cell death. This seems to lead to glia cell activation as well as the invasion of microglia, which might be associated with debris clearance.

The ability to use mesenchymal stromal cells (MSC) directly out of cryostorage would significantly reduce the logistics of MSC therapy by allowing on-site cryostorage of therapeutic doses of MSC at hospitals and clinics. Such a paradigm would be especially advantageous for the treatment of acute conditions such as stroke and myocardial infarction, which are likely to require treatment within hours after ischemic onset. Recently, several reports have emerged that suggest MSC viability and potency are damaged by cryopreservation. Herein we examine the effect of cryopreservation on human MSC viability, immunomodulatory potency, growth factor secretion and performance in an ischemia/reperfusion injury model. Using modifications of established cryopreservation methods we developed MSC that retain >95% viability upon thawing, remain responsive to inflammatory signals and are able to suppress activated human peripheral blood mononuclear cells. Most importantly, when injected into the eyes of mice 3 hours after the onset of ischemia and 2 hours after the onset of reperfusion, cryopreserved performed as well as fresh MSC to rescue retinal ganglion cells. Thus, our data suggests when viability is maintained throughout the cryopreservation process, MSC retain their therapeutic potency in both in vitro potency assays and an in vivo ischemia/reperfusion model.