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.

Currently, retinal pigment epithelium (RPE) transplantation includes sheet and single-cell transplantation, the latter of which includes cell death and may be highly immunogenic, and there are some issues to be improved in single-cell transplantation. Y-27632 is an inhibitor of Rho-associated protein kinase (ROCK), the downstream kinase of Rho. We herein investigated the effect of Y-27632 in vitro on retinal pigment epithelium derived from induced pluripotent stem cells (iPS-RPE cells), and also its effects in vivo on the transplantation of iPS-RPE cell suspensions. As a result, the addition of Y-27632 in vitro showed suppression of apoptosis, promotion of cell adhesion, and higher proliferation and pigmentation of iPS-RPE cells. Y-27632 also increased the viability of the transplant without showing obvious retinal toxicity in human iPS-RPE transplantation into monkey subretinal space in vivo. Therefore, it is possible that ROCK inhibitors can improve the engraftment of iPS-RPE cell suspensions after transplantation.

Purpose: To report occurrence of acute severe inflammation after surgical implantation of mycoplasma-infected induced pluripotent stem cell–derived RPE (iPS-RPE) cells into the eyes of healthy primates, and determine the immunopathological mechanisms of the inflammation. Methods: Ophthalmic allogeneic transplantation of iPS-RPE cells was performed in the subretina of major histocompatibility complex (MHC)-matched (two eyes) and MHC-mismatched (one eye) healthy cynomolgus monkeys. The clinical course after transplantation was observed using color fundus photography, fluorescence angiography, and optical coherence tomography. After the animals were killed at 1 month after surgery, eyeballs were removed and pathologically examined. Microorganisms were analyzed by PCR methods and BLAST analysis using preserved graft iPS-RPE cells and the recipients' vitreous humor. Mixed lymphocyte-RPE assay was performed on the mycoplasma-infected and noninfected iPS-RPE cells in vitro. Results: In tested eyes, abnormal findings were observed in the grafted retina 2 weeks after surgery. Here, we observed retinal vasculitis and hemorrhage, retinal detachment, and infiltration of inflammatory cells into the retina of the eyes. One month after surgery, animals were killed due to the severe immune responses observed. Using PCR methods, sequence analysis detected mycoplasma-DNA (Mycoplasma arginini species) in both the grafted RPE cells and the collected vitreous fluids of the monkeys. Mixed lymphocyte-RPE assay revealed that the infected iPS-RPE cells enhanced the proliferation of inflammatory cells in vitro. Conclusions: Transplantation of graft iPS-RPE cells contaminated with mycoplasma into the subretina caused severe ocular inflammation. Mycoplasma possesses the ability to cause immune responses in the host.

In an intraocular inflammatory state, microglia residing in the retina become active and migrate inside the retina. In this study, we investigated whether cyclooxygenase-1 (COX-1) expressed by retinal microglia/macrophage can be a biomarker for the diagnosis of retinal diseases. COX-1 was immunopositive in microglia/macrophage and neutrophils, while COX-2 was immunopositive in astrocytes and neurons in the inner layer of normal retina. The number of COX-1 positive cells per section of the retinal tissue was 14 ± 2.8 (mean ± standard deviation) in normal mice, which showed significant increase in the lipopolysaccharide (LPS)-administrated model (62 ± 5.0, p = 8.7 × 10⁻⁹). In addition to microglia, we found neutrophils that were positive for COX-1. In the early stage of inflammation in the experimental autoimmune uveoretinitis (EAU), COX-1 positive cells, infiltrating from the ciliary body into the retinal outer nuclear layer, were observed. The number of infiltrating COX-1 positive cells correlated with the severity of EAU. Taken together, the increased number of COX-1 positive microglia/macrophage with morphological changes were observed in the retinas of retinal inflammatory disease models. This suggests that COX-1 can be a marker of disease-related activities of microglia/macrophage, which should be useful for the diagnosis of retinal diseases.

The occurrence of ocular metastasis from lung cancer is uncommon. The present study reports the case of a 69-year-old female patient with lung adenocarcinoma who was found to have a metastatic lesion in the left choroid at the time of presentation. As the patient was found to have a mutation in the epidermal growth factor receptor, treatment with gefitinib was administered; however, the response was evaluated as a progressive disease. Thereafter, the patient received chemotherapy with carboplatin, pemetrexed and bevacizumab. Radiological imaging revealed shrinkage of the primary lesion and choroidal metastasis, and the visual power of the left eye was also shown to improve. Therefore, the present case report demonstrated the efficacy and safety of systemic bevacizumab therapy in combination with a platinum doublet for the treatment of choroid metastasis, with morphological and functional improvements observed with regard to the choroidal metastatic tumor.