A Strategy for Personalized Treatment of iPS-Retinal Immune Rejections Assessed in Cynomolgus Monkey Models.

Recently, we successfully transplanted an autograft, or major histocompatibility complex (MHC)-matched allografts, from induced-pluripotent-stem-cell-derived retinal pigment epithelial (iPSC-RPE) cells in patients with age-related macular degeneration. However, there was an issue regarding immune rejection after transplantation. In this study, we established a preoperational in vitro "drug-lymphocytes-grafts immune reaction (Drug-LGIR)" test to determine the medication for immune rejection using host immunocompetent cells (lymphocytes) and transplant cells (target iPSC-RPE cells) together with different medications. The adequacy of the test was assessed by in vivo transplantation in monkey models together with medication based on in vitro data. In the results of Drug-LGIR tests, some drugs exhibited significant suppression of RPE cell-related allogeneic reactions, while other drugs did not, and the efficacy of each drug differed among the recipient monkeys. Based on the results of Drug-LGIR, we applied cyclosporine A or local steroid (triamcinolone) therapy to two monkeys, and successfully suppressed RPE-related immune rejections with RPE grafts, which survived without any signs of rejection under drug administration. We propose that our new preoperational in vitro Drug-LGIR test, which specifies the most efficacious medication for each recipient, is useful for controlling immune attacks with personalized treatment for each patient after retinal transplantation.

Development of singlet oxygen absorption capacity (SOAC) assay method. 4. Measurements of the SOAC values for vegetable and fruit extracts.

Measurements of the second-order rate constants and the singlet oxygen absorption capacity (SOAC) values for the reaction of singlet oxygen ((1)O2) with 23 kinds of food extracts were performed in ethanol/chloroform/D2O (50:50:1, v/v/v) solution at 35 °C. It has been clarified that the SOAC method is useful to evaluate the (1)O2-quenching activity (i.e. the SOAC value) of food extracts having two orders of magnitude different rate constants from 3.18 × 10(4) L g(-1) s(-1) for tomato to 1.55 × 10(2) for green melon. Furthermore, comparison of the observed rate constants for the above food extracts with the calculated ones based on the concentrations of seven kinds of carotenoids included in the food extracts and the rate constants reported for each carotenoids was performed, in order to ascertain the validity of the SOAC assay method developed and to clarify the ratio of the contribution of principal carotenoids to the SOAC value.

Crucial role of a long-chain fatty acid elongase, Elovl6, in obesity-induced insulin resistance.

Insulin resistance is often associated with obesity and can precipitate type 2 diabetes. To date, most known approaches that improve insulin resistance must be preceded by the amelioration of obesity and hepatosteatosis. Here, we show that this provision is not mandatory; insulin resistance and hyperglycemia are improved by the modification of hepatic fatty acid composition, even in the presence of persistent obesity and hepatosteatosis. Mice deficient for Elovl6, the gene encoding the elongase that catalyzes the conversion of palmitate to stearate, were generated and shown to become obese and develop hepatosteatosis when fed a high-fat diet or mated to leptin-deficient ob/ob mice. However, they showed marked protection from hyperinsulinemia, hyperglycemia and hyperleptinemia. Amelioration of insulin resistance was associated with restoration of hepatic insulin receptor substrate-2 and suppression of hepatic protein kinase C epsilon activity resulting in restoration of Akt phosphorylation. Collectively, these data show that hepatic fatty acid composition is a new determinant for insulin sensitivity that acts independently of cellular energy balance and stress. Inhibition of this elongase could be a new therapeutic approach for ameliorating insulin resistance, diabetes and cardiovascular risks, even in the presence of a continuing state of obesity.

CLINICOPATHOLOGICAL ANALYSIS OF SECONDARY RETINAL VASOPROLIFERATIVE TUMOR/REACTIVE RETINAL ASTROCYTIC TUMOR SUCCESSFULLY TREATED BY ENDORESECTION.

PURPOSE: To report the clinicopathological findings of retinal vasoproliferative tumor/reactive retinal astrocytic tumor (VPT/RRAT) with retinal vasculitis, treated by tumor resection. METHODS: A retrospective single case report. PATIENT: A 29-year-old Japanese woman was referred with cystoid macular edema and retinal vasculitis in the right eye. Best-corrected visual acuity was 0.9. Results of fundus examination, optical coherence tomography, and fluorescein angiography demonstrated VPT/RRATs in the temporal retina surrounded by a subretinal exudate, serous retinal detachment and macular edema, and retinal vasculitis. Despite 3 months of oral prednisolone treatment, a full-thickness macular hole developed. Pars plana vitrectomy and endoresection of the VPT/RRATs were performed. Pathologic and immunohistochemical analyses with anti-CD34 antibody, antiglial fibrillary acidic protein antibody, anti-Ki67 antibody, and anti-vascular endothelial growth factor antibody were performed on the excised tissue. Inflammation was evaluated by immunohistological staining with leukocyte common antigen (LCA), anti-CD3 antibody, and anti-CD20 antibody. RESULTS: After surgery, the macular hole closed, best-corrected visual acuity improved to 1.2, retinal vasculitis was ameliorated, and retinal exudate disappeared. There was no recurrence of VPT/RRAT or retinal vasculitis. Pathologic examination showed that antiglial fibrillary acidic protein and anti-vascular endothelial growth factor were widely expressed, irrespective of the distribution of blood vessels. Ki67-positive proliferating cells were detected in the perivascular area. Leukocyte common antigen-positive leukocytes and CD3-positive T cells were detected throughout the samples, whereas CD20-positive B cells were rarely detected. CONCLUSION: Endoresection of VPT/RRAT could be a good treatment option for secondary VPT/RRAT accompanied by retinal vasculitis. Pathologic findings revealed for the first time that inflammatory cells infiltrate the tissue in secondary VPT/RRAT.

Translational response to mitochondrial stresses is orchestrated by tRNA modifications.

Mitochondrial stress and dysfunction play important roles in many pathologies. However, how cells respond to mitochondrial stress is not fully understood. Here, we examined the translational response to electron transport chain (ETC) inhibition and arsenite induced mitochondrial stresses. Our analysis revealed that during mitochondrial stress, tRNA modifications (namely f5C, hm5C, queuosine and its derivatives, and mcm5U) dynamically change to fine tune codon decoding, usage, and optimality. These changes in codon optimality drive the translation of many pathways and gene sets, such as the ATF4 pathway and selenoproteins, involved in the cellular response to mitochondrial stress. We further examined several of these modifications using targeted approaches. ALKBH1 knockout (KO) abrogated f5C and hm5C levels and led to mitochondrial dysfunction, reduced proliferation, and impacted mRNA translation rates. Our analysis revealed that tRNA queuosine (tRNA-Q) is a master regulator of the mitochondrial stress response. KO of QTRT1 or QTRT2, the enzymes responsible for tRNA-Q synthesis, led to mitochondrial dysfunction, translational dysregulation, and metabolic alterations in mitochondria-related pathways, without altering cellular proliferation. In addition, our analysis revealed that tRNA-Q loss led to a domino effect on various tRNA modifications. Some of these changes could be explained by metabolic profiling. Our analysis also revealed that utilizing serum deprivation or alteration with Queuine supplementation to study tRNA-Q or stress response can introduce various confounding factors by altering many other tRNA modifications. In summary, our data show that tRNA modifications are master regulators of the mitochondrial stress response by driving changes in codon decoding.

Granulomatosis with Polyangiitis Complicated by Severe Exudative Retinal Detachment and Orbital Granuloma Successfully Controlled with Rituximab: A Case Report.

We report a rare case of severe exudative retinal detachment with orbital granuloma associated with granulomatosis with polyangiitis (GPA). A 42-year-old man developed bilateral conjunctival hyperemia and eye pain 15 months before presenting to us. Because vitreous cells and retinal detachment were detected in his left eye, he was referred to us for further evaluation. The left eye showed scleral edema, cells in the anterior chamber and anterior vitreous, exudative retinal detachment, and elevated white subretinal lesions from the nasal to the inferior parts of the eye fundus. Orbital contrast-enhanced magnetic resonance imaging revealed a granulomatous lesion, retinal detachment, and fluid retention in the left eyeball. Comprehensive rheumatological evaluation revealed proteinase 3 anti-neutrophil cytoplasmic antibody positivity and a history of otitis media, leading to a GPA diagnosis. Methylprednisolone 1,000 mg/day was administered intravenously for 3 days, followed by oral prednisolone and intravenous cyclophosphamide. Although the retinal detachment decreased, scleritis and choroidal detachment relapse were observed in the left eye after the fifth cyclophosphamide administration. After switching from cyclophosphamide to rituximab, the scleritis and choroidal detachment resolved. Remission was successfully maintained with biannual rituximab administration. In this case, we conclude that rituximab was important to re-induce and maintain remission after recurrence. Collaboration with a rheumatologist is essential for proper treatment in related cases. This is the first report of ultra-widefield and multimodal imaging for retinal detachment associated with GPA.

Challenges in the diagnosis and management of vitreoretinal lymphoma - Clinical and basic approaches.

Vitreoretinal lymphoma (VRL) is a subtype of diffuse large B-cell lymphoma and is sight- and life-threatening in the vast majority of patients. Lymphoma cells infiltrate the vitreous body and/or subretinal space and exhibit clinical signs of vitreous opacities and creamy white subretinal lesions. Although the intraocular signs can serve as clues to suspect VRL, they are nonspecific and may be misdiagnosed as uveitis. Histopathological evidence of malignant cells on vitreous biopsy, for instance, is the gold standard for diagnosis of VRL; however, cytological examination of the vitreous often results in a low success rate owing to the small quantity and poor quality of tissues and cells in the sample. Recent advancements in immunological, molecular, and gene analyses using intraocular samples have made it possible to accurately diagnose VRL. As for the management of VRL, local treatments with irradiation and/or intravitreal injections of anti-tumor agents (methotrexate or rituximab) are effective in suppressing intraocular VRL lesions. However, the effect of systemic chemotherapy, with or without brain irradiation, on preventing central nervous system involvements remains controversial. In this review article, we discuss the following concepts based on previous literature and our unpublished results: current ocular imaging examinations such as optical coherence tomography and fundus autofluorescence; immunological, molecular, and gene expression characterization of intraocular biopsies with special attention to flow cytometry; immunoglobulin gene rearrangement assays that use the polymerase chain reaction test; cytokine assays; gene mutations (MYD88, CD79B); and current local and systemic treatments of VRL.

Discrimination of dissociated lymphoma cells from leukocytes by Raman spectroscopy.

Diagnosis of intraocular lymphoma is difficult. Among the hurdles in the diagnosis are the variety of reactive inflammatory and ischemic changes among intraocular lymphoma patients. Thus, a novel diagnostic method is desired such that lymphoma cells can be distinguished by the signals intrinsic to the cells, not by those from the surrounding tissues with reactive changes. Raman spectroscopy is a technique that can detect intrinsic signals from each cell. Therefore, Raman spectroscopy is a good candidate for an intraocular evaluation technology that could contribute to improve the diagnosis of intraocular lymphoma. In this study, we tested whether the intrinsic Raman signals from malignant lymphoma cells, in the absence of surrounding tissue, were sufficient for the discrimination of malignant lymphoma cells from leukocytes. We acquired spectra from dissociated lymphoma cells, along with spectra from normal B cells and other leukocytes involved in intraocular inflammatory diseases. We analysed the spectra using principal component analyses and quadratic discriminant analyses. We found that Raman spectra from dissociated cells without confounding tissues showed high discriminating ability, regardless of the variation due to day-to-day differences and donor differences. The present study demonstrates the possible effectiveness of Raman spectroscopy as a tool for intraocular evaluation.

A 10-year follow-up of infliximab monotherapy for refractory uveitis in Behçet's syndrome.

Infliximab (IFX) was the first biologic introduced for refractory uveitis treatment in Behçet's syndrome (BS). However, there have been few reports on the safety and efficacy of IFX monotherapy over follow-up periods of more than 10 years. This retrospective study evaluated the 10-year safety and efficacy of IFX monotherapy compared to IFX combination therapies with colchicine or corticosteroid for refractory uveitis in BS patients. Monotherapy was performed in 30 eyes of 16 patients while combination therapies were performed in 20 eyes of 11 patients. Continuation of IFX occurred in 70.3% of enrolled patients for 10 years without any significant difference noted in the retention rate between the monotherapy and combination therapies (p = 0.86). Reduction of ocular inflammatory attacks and improvement of best corrected visual acuity occurred in the monotherapy group after 10 years, which was equivalent to that for the combination therapies. Although adverse events (AEs) or therapy discontinuation occurred during the initial 5 years in both therapies, no AEs were observed for either therapy after 6 years. Our results suggested that IFX monotherapy proved to be effective and not inferior to combination therapies over a 10-year follow-up. Although loss of response and AEs may be noticed during the initial 5-year period, a safe and effective continuation can be expected thereafter.

Nuclear SREBP-1a causes loss of pancreatic beta-cells and impaired insulin secretion.

Transgenic mice expressing nuclear sterol regulatory element-binding protein-1a under the control of the insulin promoter were generated to determine the role of SREBP-1a in pancreatic beta-cells. Only low expressors could be established, which exhibited mild hyperglycemia, impaired glucose tolerance, and reduced plasma insulin levels compared to C57BL/6 controls. The islets isolated from the transgenic mice were fewer and smaller, and had decreased insulin content and unaltered glucagon staining. Both glucose- and potassium-stimulated insulin secretions were decreased. The transgenic islets consistently expressed genes for fatty acids and cholesterol synthesis, resulting in accumulation of triglycerides but not cholesterol. PDX-1, BetaEpsilonTauAlpha2, MafA, and IRS-2 were suppressed, partially explaining the loss and dysfunction of beta-cell mass. The transgenic mice on a high fat/high sucrose diet still exhibited impaired insulin secretion and continuous beta-cell growth defect. Therefore, nuclear SREBP-1a, even at a low level, strongly disrupts beta-cell mass and function.

Two states of active spermatogenesis switch between reproductive and non-reproductive seasons in the testes of the medaka, Oryzias latipes.

Seasonal change in spermatogenesis was examined in the restricted spermatogonium-type testes of a teleost, Oryzias latipes. Histological observation revealed that the number of each stage of germ cells during most of the non-reproductive season, from October to January (O-J period) was nearly half of that during the reproductive season, from May to July (M-J period), except for type B spermatogonia (B-gonia), which was actually equal. As a result, the ratio of primary spermatocytes (P-cytes) to B-gonia was remarkably small in the O-J period. Despite the differences between both time periods, the proliferative activity of type A spermatogonia (A-gonia), B-gonia, or P-cytes was at a similar level in both periods. Moreover, in cultured testes treated with bromodeoxyuridine as a cell-lineage tracer, P-cytes differentiated to spermatids in 11-15 days in both M-J and O-J periods. These indicate that spermatogenesis is active in each period at a different state. In the spermatogenic testis, A-gonial proliferation was maintained by human follicle stimulating hormone/luteinizing hormone in culture. Whereas cell death of B-gonia and/or P-cytes gradually increased in the M-J period in spite of those cells being constant in population sizes. In transition to the O-J period, A-gonia and P-cytes first decreased, which was accompanied by a decrease in proliferative activity of A-gonia and relative increase of dead cells from B-gonia and/or P-cytes against live P-cytes. These suggest that A-gonial proliferation and cell death of B-gonia and/or P-cytes that is induced coordinately with B-gonial differentiation are critical for the spermatogenic control.

Transient Lesion of the Splenium of the Corpus Callosum after Acute Ischemic Stroke.

Two patients who showed transient lesions in the splenium of the corpus callosum (SCC) secondary to acute ischemic stroke are reported. Both patients had embolic strokes and showed an isolated lesion in the SCC on magnetic resonance imaging (MRI) 1-2 weeks after the onset of stroke, with a hyperintense lesion on diffusion-weighted imaging and decreased apparent diffusion coefficient values, with no symptoms related to the lesion. In both cases, the lesion disappeared on MRI approximately 1 week later. Clinicians should note that transient SCC lesions can occur following acute ischemic stroke and avoid misdiagnosing them and performing unnecessary examinations or treatment.

Visual arrestin modulates gene expression in the retinal pigment epithelium: Implications for homeostasis in the retina.

The retinal pigment epithelium (RPE) is essential for maintaining retinal homeostasis by removing and recycling photoreceptor outer segment (POS) in membranes. It also produces and secretes growth factors involved in retinal homeostasis. Arrestin 1 (ARR1) is specifically expressed in photoreceptors (PRs) and a vital molecule for keeping visual cycle between PRs and RPE. In the present study, we showed the expression of ARR1 was decreased by form-deprivation (FD) in retina of rat. The ARR1 was detected in the RPE of the controls but not in the RPE of FD, which indicates RPE phagocytes POS containing ARR1. Furthermore, we overexpressed ARR1 in cultured human RPE and revealed the ARR1 upregulates bFGF expression and downregulates TGF-ß1, -ß2 and bone morphogenetic protein-2 (BMP-2). The upregulation of bFGF by ARR1 directly works for PR survival and the downregulation of TGF-ßs by ARR1 inhibits epithelial mesenchymal transition (EMT) of RPE, which is the underlying mechanism of keeping retinal homeostasis. Our results also indicate the regulation of ARR1 expression in RPE might become a novel therapeutic option for various ocular diseases.

Natural Killer Cell Inhibition by HLA-E Molecules on Induced Pluripotent Stem Cell-Derived Retinal Pigment Epithelial Cells.

Purpose: To determine whether human induced pluripotent stem (iPS) cell-derived retinal pigment epithelial (RPE) cells (iPS-RPE) can suppress natural killer (NK) cell activation. Methods: iPS-RPE cells were cocultured with peripheral blood mononuclear cells (PBMCs) or purified NK cells from healthy donors after stimulation with cytokines. To confirm expression of NK cell-specific markers, flow cytometry and quantitative RT-PCR (qRT-PCR) were performed. NK cells (or PBMCs) cocultured with iPS-RPE cells were assessed for proliferation by Ki-67 expression with flow cytometry, and NK suppression by RPE cells was assessed for granzyme B production with ELISA. Human leukocyte antigen (HLA) expression including HLA-E on iPS-RPE cells was evaluated with flow cytometry and qRT-PCR. The effect of HLA-E downregulation was also investigated using small interfering RNA (siRNA) systems. Following iPS-RPE cell transplantation in vivo, we evaluated NK cell invasion in the retina with immunohistochemistry. Results: Activated NK cells expressed NK-related markers such as CD16, CD56, and CD11b, and NK cells produced cytotoxic agents such as granzyme B, perforin, and TNF-α. Human iPS-RPE cells inhibited cell proliferation and production of these cytotoxic agents by activated NK cells in vitro. iPS-RPE cells constitutively expressed HLA-E and suppressed NK cell activation through an interaction between HLA-E and CD94/NKG2A. Moreover, immunohistochemical evaluation of monkey RPE transplantation into in vivo immune rejection models showed no NK cell invasion in the retina in allografts or xenografts except for one xenografted eye. Conclusions: Cultured iPS cell-derived RPE cells greatly suppress NK cell activation. Thus, NK cells might be inactivated when exposed to this type of retinal cell.

Detection of Retinal Pigment Epithelium-Specific Antibody in iPSC-Derived Retinal Pigment Epithelium Transplantation Models.

Antibody-mediated rejection is characterized by donor-specific antibody produced by B cells. However, to our knowledge, B cell invasion and antibody in the inflamed retina after transplantation of retinal pigment epithelial (RPE) cells has not been reported. To determine if RPE transplantation could be performed using allografts, we established in vivo immune rejection models with induced pluripotent stem cell (iPSC)-RPE allografts and determined whether RPE-specific antibody could be detected in these models. We detected alloantibodies in the serum from recipient monkeys that had immune attacks in the retina in an immunofluorescent assay using the transplanted iPSC-RPE cells as the antigen. In addition to T cell and antigen-presenting cell immunity, peripheral blood cells and lymph nodes in animal models with allogeneic iPSC-RPE cells also had activated B cells, which were probably secreting alloantibodies. Using serum and transplanted cells, alloreactive antibody can be detected for the diagnosis of immune rejection after transplantation.

A case of MOG antibody-positive bilateral optic neuritis and meningoganglionitis following a genital herpes simplex virus infection.

BACKGROUND: Myelin oligodendrocyte glycoprotein (MOG) antibody-positive optic neuritis (ON) and myelitis are recognized as important differential diagnosis of aquaporin-4 (AQP4) antibody-positive neuromyelitis optica (NMO)/NMO spectrum disorder (NMOSD). Similar to NMO/NMOSD associated with AQP4 antibodies, preceding infections have been reported in patients with MOG antibody-positive ON. This is the first report of bilateral ON following a herpes simplex virus (HSV) infection associated with a positive MOG antibody. CASE PRESENTATION: A 41-year-old man who initially presented with genital herpes developed allodynia in the Th2-Th5 and Th8-L2 areas, urinary retention, and painful visual loss in the left eye. Ophthalmological evaluation and brain magnetic resonance imaging (MRI) revealed bilateral ON. A spinal MRI showed leptomeningeal enhancement from the thoracic to lumbar vertebrae and abnormal enhancement of the L3 to S3 dorsal root ganglia without a change in intramedullary signals. Following treatment with acyclovir and steroid pulse, he fully recovered. Serum anti-AQP4 antibodies were negative, but anti-MOG antibodies were positive. Finally, he was diagnosed with MOG antibody-positive bilateral ON and meningoganglionitis following an HSV infection. CONCLUSION: Our case supports a relationship between anti-MOG antibodies and ON triggered by an HSV infection. Clinicians should thus consider testing for MOG antibodies in patients with post-infectious neurological symptoms due to an HSV infection.

Leptomeningeal Collaterals Strongly Correlate with Reduced Cerebrovascular Reactivity Measured by Acetazolamide-challenged Single-photon Emission Computed Tomography Using a Stereotactic Extraction Estimation Analysis in Patients with Unilateral Internal Carotid Artery Stenosis.

Objective To assess the correlation between the angiographic appearance of cerebral collateral pathways or the degree of internal carotid artery stenosis (ICAS) and reduced cerebrovascular reactivity (CVR) estimated by single-photon emission computed tomography (SPECT) image analysis in patients with unilateral ICAS. Methods A retrospective analysis was performed in 42 patients with unilateral ICAS who underwent cerebral angiography and acetazolamide-challenged SPECT of the brain. Cerebral blood flow quantitation was performed using the quantitative SPECT/dual-table autoradiography method. The CVR in the middle cerebral artery (MCA) territory was evaluated using the stereotactic extraction estimation based on the Japanese extracranial-intracranial bypass trial (SEE-JET) program and classified as reduced (<18.4%) or non-reduced (≥18.4%). Angiographic collateralization was classified as circle of Willis (type 1), extracranial-intracranial (type 2), and leptomeningeal (type 3). The degree of ICAS was defined as severe (≥70% stenosis) or non-severe (<70%). Results Eight patients showed reduced CVR, including 6 (46%) of 13 with type 3 collaterals and 2 (7%) of 29 without type 3 collaterals (p=0.006). In contrast, type 1 and type 2 collaterals and severe ICAS were not significantly associated with reduced CVR. Conclusion In patients with unilateral ICAS, leptomeningeal collaterals are strongly correlated with reduced CVR in the MCA territory, which presumably increases the risk of cerebral hyperperfusion after carotid artery stenting (CAS). Therefore, these findings may be clinically applicable to the perioperative management of CAS.

Lack of T Cell Response to iPSC-Derived Retinal Pigment Epithelial Cells from HLA Homozygous Donors.

Allografts of retinal pigment epithelial (RPE) cells have been considered for the treatment of ocular diseases. We recently started the transplantation of induced pluripotent stem cell (iPSC)-derived RPE cells for patients with age-related macular degeneration (autogenic grafts). However, there are at least two problems with this approach: (1) high cost, and (2) uselessness for acute patients. To resolve these issues, we established RPE cells from induced iPSCs in HLA homozygote donors. In vitro, human T cells directly recognized allogeneic iPSC-derived RPE cells that expressed HLA class I/II antigens. However, these T cells failed to respond to HLA-A, -B, and -DRB1-matched iPSC-derived RPE cells from HLA homozygous donors. Because of the lack of T cell response to iPSC-derived RPE cells from HLA homozygous donors, we can use these allogeneic iPSC-derived RPE cells in future clinical trials if the recipient and donor are HLA matched.

Differentiation/Purification Protocol for Retinal Pigment Epithelium from Mouse Induced Pluripotent Stem Cells as a Research Tool.

PURPOSE: To establish a novel protocol for differentiation of retinal pigment epithelium (RPE) with high purity from mouse induced pluripotent stem cells (iPSC). METHODS: Retinal progenitor cells were differentiated from mouse iPSC, and RPE differentiation was then enhanced by activation of the Wnt signaling pathway, inhibition of the fibroblast growth factor signaling pathway, and inhibition of the Rho-associated, coiled-coil containing protein kinase signaling pathway. Expanded pigmented cells were purified by plate adhesion after Accutase® treatment. Enriched cells were cultured until they developed a cobblestone appearance with cuboidal shape. The characteristics of iPS-RPE were confirmed by gene expression, immunocytochemistry, and electron microscopy. Functions and immunologic features of the iPS-RPE were also evaluated. RESULTS: We obtained iPS-RPE at high purity (approximately 98%). The iPS-RPE showed apical-basal polarity and cellular structure characteristic of RPE. Expression levels of several RPE markers were lower than those of freshly isolated mouse RPE but comparable to those of primary cultured RPE. The iPS-RPE could form tight junctions, phagocytose photoreceptor outer segments, express immune antigens, and suppress lymphocyte proliferation. CONCLUSION: We successfully developed a differentiation/purification protocol to obtain mouse iPS-RPE. The mouse iPS-RPE can serve as an attractive tool for functional and morphological studies of RPE.

Successful Transplantation of Retinal Pigment Epithelial Cells from MHC Homozygote iPSCs in MHC-Matched Models.

There is an ongoing controversy as to whether major histocompatibility complex (MHC) matching is a solution for allogeneic stem cell transplantation. In the present study, we established retinal pigment epithelial (RPE) cells from induced pluripotent stem cells (iPSCs) in MHC homozygote donors. We observed no rejection signs in iPSC-derived RPE allografts of MHC-matched animal models without immunosuppression, whereas there were immune attacks around the graft and retinal tissue damage in MHC-mismatched models. In an immunohistochemical examination of MHC-mismatched allografts, the transplanted RPE sheets/cells were located in the subretinal space, but the RPE exhibited inflammatory and hypertrophic changes, and many inflammatory cells, e.g., Iba1+ cells, MHC class II+ cells, and CD3+ T cells, invaded the graft area. Conversely, these inflammatory cells poorly infiltrated the area around the transplanted retina if MHC-matched allografts were used. Thus, cells derived from MHC homozygous donors could be used to treat retinal diseases in histocompatible recipients.