Integrator complex subunit 15 controls mRNA splicing and is critical for eye development.

The eye and brain are composed of elaborately organized tissues, development of which is supported by spatiotemporally precise expression of a number of transcription factors and developmental regulators. Here we report the molecular and genetic characterization of Integrator complex subunit 15 (INTS15). INTS15 was identified in search for the causative gene(s) for an autosomal-dominant eye disease with variable individual manifestation found in a large pedigree. While homozygous Ints15 knockout mice are embryonic lethal, mutant mice lacking a small C-terminal region of Ints15 show ocular malformations similar to the human patients. INTS15 is highly expressed in the eye and brain during embryogenesis and stably interacts with the Integrator complex to support small nuclear RNA 3' end processing. Its knockdown resulted in missplicing of a large number of genes, probably as a secondary consequence, and substantially affected genes associated with eye and brain development. Moreover, studies using human iPS cells-derived neural progenitor cells showed that INTS15 is critical for axonal outgrowth in retinal ganglion cells. This study suggests a new link between general transcription machinery and a highly specific hereditary disease.

The Structural Abnormalities Are Deeply Involved in the Cause of RPGRIP1-Related Retinal Dystrophy in Japanese Patients.

Leber congenital amaurosis (LCA) is the most severe form of inherited retinal dystrophy. RPGRIP1-related LCA accounts for 5-6% of LCA. We performed whole-exome sequencing and whole-genome sequencing (WGS) on 29 patients with clinically suspected LCA and examined ophthalmic findings in patients with biallelic pathogenic variants of RPGRIP1. In addition to five previously reported cases, we identified five cases from four families with compound heterozygous RPGRIP1 variants using WGS. Five patients had null variants comprising frameshift variants, an Alu insertion, and microdeletions. A previously reported 1339 bp deletion involving exon 18 was found in four cases, and the deletion was relatively prevalent in the Japanese population (allele frequency: 0.002). Microdeletions involving exon 1 were detected in four cases. In patients with RPGRIP1 variants, visual acuity remained low, ranging from light perception to 0.2, and showed no correlation with age. In optical coherence tomography images, the ellipsoid zone (EZ) length decreased with age in all but one case of unimpaired EZ. The retinal structure was relatively preserved in all cases; however, there were cases with great differences in visual function compared to their siblings and a 56-year-old patient who still had a faint EZ line. Structural abnormalities may be important genetic causes of RPGRIP1-related retinal dystrophy in Japanese patients, and WGS was useful for detecting them.

Effect of Intravitreal Aflibercept vs Laser Photocoagulation on Treatment Success of Retinopathy of Prematurity: The FIREFLEYE Randomized Clinical Trial.

Importance: Laser photocoagulation, which is the standard treatment for retinopathy of prematurity (ROP), can have adverse events. Studies of anti-vascular endothelial growth factor injections have suggested efficacy in the treatment of ROP, but few studies have directly compared them with laser treatments. Objective: To compare intravitreal aflibercept vs laser photocoagulation in infants with ROP requiring treatment. Design, Setting, and Participants: This noninferiority, phase 3, 24-week, randomized clinical trial was conducted in 27 countries (64 hospital sites) throughout Asia, Europe, and South America. Overall, 118 infants (gestational age ≤32 weeks at birth or birth weight ≤1500 g) with ROP severity (zone I stage 1+ [stage 1 plus increased disease activity], zone I stage 2+, zone I stage 3, zone I stage 3+, zone II stage 2+, or zone II stage 3+) requiring treatment or with aggressive posterior ROP in at least 1 eye were enrolled between September 25, 2019, and August 28, 2020 (the last visit occurred on February 12, 2021). Interventions: Infants were randomized 2:1 to receive a 0.4-mg dose of intravitreal aflibercept (n = 75) or laser photocoagulation (n = 43) at baseline. Additional treatment was allowed as prespecified. Main Outcomes and Measures: The primary outcome was the proportion of infants without active ROP and unfavorable structural outcomes 24 weeks after starting treatment (assessed by investigators). The requirement for rescue treatment was considered treatment failure. Intravitreal aflibercept was deemed noninferior if the lower limit of the 1-sided 95% bayesian credible interval for the treatment difference was greater than -5%. Results: Among 118 infants randomized, 113 were treated (mean gestational age, 26.3 [SD, 1.9] weeks; 53 [46.9%] were female; 16.8% had aggressive posterior ROP, 19.5% had zone I ROP, and 63.7% had zone II ROP) and 104 completed the study. Treatment (intravitreal aflibercept: n = 75; laser photocoagulation: n = 38) was mostly bilateral (92.9%), and 82.2% of eyes in the intravitreal aflibercept group received 1 injection per eye. Treatment success was 85.5% with intravitreal aflibercept vs 82.1% with laser photocoagulation (between-group difference, 3.4% [1-sided 95% credible interval, -8.0% to ∞]). Rescue treatment was required in 4.8% (95% CI, 1.9% to 9.6%) of eyes in the intravitreal aflibercept group vs 11.1% (95% CI, 4.9% to 20.7%) of eyes in the laser photocoagulation group. The serious adverse event rates were 13.3% (ocular) and 24.0% (systemic) in the intravitreal aflibercept group compared with 7.9% and 36.8%, respectively, in the laser photocoagulation group. Three deaths, which occurred 4 to 9 weeks after intravitreal aflibercept treatment, were considered unrelated to aflibercept by the investigators. Conclusions and Relevance: Among infants with ROP, intravitreal aflibercept compared with laser photocoagulation did not meet criteria for noninferiority with respect to the primary outcome of the proportion of infants achieving treatment success at week 24. Further data would be required for more definitive conclusions regarding the comparative effects of intravitreal aflibercept and laser photocoagulation in this population. Trial Registration: ClinicalTrials.gov Identifier: NCT04004208.

Biallelic CDK9 variants as a cause of a new multiple-malformation syndrome with retinal dystrophy mimicking the CHARGE syndrome.

CDK9 has been considered a candidate gene involved in the CHARGE-like syndrome in a pair of cousins. We report an 8-year-old boy with a strikingly similar phenotype including facial asymmetry, microtia with preauricular tags and bilateral hearing loss, cleft lip and palate, cardiac dysrhythmia, and undescended testes. Joint contracture, no finger flexion creases, and large halluces were the same as those of a previously reported patient with homozygous CDK9 variants. The ocular phenotype included blepharophimosis, lacrimal duct obstruction, eyelid dermoids, Duane syndrome-like abduction deficit, and congenital cataracts. Optical coherence tomography and electroretinography evaluations revealed severe retinal dystrophy had developed at an early age. Trio-based whole-exome sequencing identified compound heterozygous variants in CDK9 [p.(A288T) of maternal origin and p.(R303C) of paternal origin] in the patient. Variants' kinase activities were reduced compared with wild type. We concluded that CDK9 biallelic variants cause a CHARGE-like malformation syndrome with retinal dystrophy as a distinguishing feature.

Analysis of IKBKG/NEMO gene in five Japanese cases of incontinentia pigmenti with retinopathy: fine genomic assay of a rare male case with mosaicism.

Incontinentia pigmenti (IP) is an X-linked dominant genodermatosis that is usually lethal in utero in males, though exceptionally they survive very rarely either with Klinefelter syndrome or a somatic mosaicism. We performed genomic analysis of five Japanese IP patients including a rare boy case, all of whom were definite cases with retinopathy. Four patients including the boy revealed the recurrent exon 4-10 deletion in the sole known causative gene IKBKG/NEMO, which was confirmed by various specific PCR techniques. The boy's saliva DNA showed a mosaicism consisting of the deletion and intact alleles, but his blood DNA did not. Relative quantification analysis of the real-time PCR data by ∆∆CT method estimated the mosaicism ratio of the boy's saliva as 45:55 (deletion:intact). A genomic analysis for the recurrent deletion at the nucleotide sequence level has been performed directly using patient's DNA and it has been clarified that the breakpoints are within two MER67B repeats in the intron 3 and downstream of exon 10. This is the first report of the assay for the mosaicism ratio of a male IP case with a recurrent exon 4-10 deletion of IKBKG/NEMO and the sequencing analysis of the breakpoints of the recurrent deletion directly using patient's sample.

X-linked Retinitis Pigmentosa in Japan: Clinical and Genetic Findings in Male Patients and Female Carriers.

X-linked retinitis pigmentosa (XLRP) is a type of severe retinal dystrophy, and female carriers of XLRP demonstrate markedly variable clinical severity. In this study, we aimed to elucidate the clinical findings of male patients with and female carriers of XLRP in a Japanese cohort and demonstrate the genetic contribution. Twelve unrelated families (13 male patients, 15 female carriers) harboring pathogenic mutations in RPGR or RP2 were included, and comprehensive ophthalmic examinations were performed. To identify potential pathogenic mutations, targeted next-generation sequencing was employed. Consequently, we identified 11 pathogenic mutations, of which five were novel. Six and five mutations were detected in RPGR and RP2, respectively. Only one mutation was detected in ORF15. Affected male patients with RP2 mutations tended to have lower visual function than those with RPGR mutations. Female carriers demonstrated varying visual acuities and visual fields. Among the female carriers, 92% had electroretinographical abnormalities and 63% had a radial autofluorescent pattern, and the carriers who had higher myopia showed worse visual acuity and more severe retinal degeneration. Our results expand the knowledge of the clinical phenotypes of male patients with and female carriers of XLRP and suggest the possibility that RP2 mutations are relatively highly prevalent in Japan.

ATYPICAL FORM OF RETINOPATHY OF PREMATURITY WITH SEVERE FIBROVASCULAR PROLIFERATION IN THE OPTIC DISK REGION.

PURPOSE: To describe severe fibrovascular proliferation that developed in the optic disk region in an atypical form of retinopathy of prematurity (ROP). METHODS: Retrospective observational case reports. RESULTS: Four patients (8 eyes) with ROP were included. Three patients were born very prematurely (24-25 weeks of gestational age; weight, 500-1,000 grams); 1 patient was born at 33 weeks of gestational age. Among all eight eyes of four patients who received prompt ROP screening and underwent laser photocoagulation, six eyes had atypical and severe fibrovascular proliferation mainly in the optic disk region; the other two eyes, including one eye with classic ROP and one eye with aggressive posterior ROP, did not have the atypical form. All eight eyes had a total to partial retinal detachment. Among the six eyes with the atypical form, early vitreous surgery with lensectomy was possible in three eyes; only late vitreous surgery with lensectomy was possible in two eyes; one eye was inoperable. Three eyes had a partial or complete reattachment, whereas three eyes had a total retinal detachment. Among the six eyes with atypical fibrovascular proliferation, only two eyes obtained light perception vision. CONCLUSION: An atypical and severe form of ROP, in which fibrovascular proliferation grew mainly from the optic disk region, needs further investigation for treatment in addition to laser photocoagulation and vitreous surgery.

Different foveal schisis patterns in each retinal layer in eyes with hereditary juvenile retinoschisis evaluated by en-face optical coherence tomography.

PURPOSE: To analyze the structures of schisis in eyes with hereditary juvenile retinoschisis using en-face optical coherence tomography (OCT) imaging. METHODS: In this retrospective observational study, we reviewed the medical records of patients with hereditary juvenile retinoschisis who underwent comprehensive ophthalmic examinations including swept-source OCT. RESULTS: OCT images were obtained from 16 eyes of nine boys (mean age ± standard deviation, 10.6 ± 4.0 years). The horizontal OCT images at the fovea showed inner nuclear layer (INL) schisis in one eye (6.3 %), ganglion cell layer (GCL) and INL schisis in 12 eyes (75.0 %), INL and outer plexiform layer (OPL) schisis in two eyes (12.5 %), and GCL, INL, and OPL schisis in one eye (6.3 %). En-face OCT images showed characteristic schisis patterns in each retinal layer, which were represented by multiple hyporeflective holes in the parafoveal region in the GCL, a spoke-like pattern in the foveal region, a reticular pattern in the parafoveal region in the INL, and multiple hyporeflective polygonal cavities with partitions in the OPL. CONCLUSIONS: Our results using en-face OCT imaging clarified different patterns of schisis formation among the GCL, INL, and OPL, which lead to further recognition of structure in hereditary juvenile retinoschisis.

SOX2 nonsense mutation in a patient clinically diagnosed with non-syndromic hypogonadotropic hypogonadism.

Hypogonadotropic hypogonadism (HH) is a genetically heterogeneous condition that occurs either as an isolated disorder or as a component of congenital malformation syndromes. SOX2 is a causative gene of syndromic HH characterized by anophthalmia, microphthalmia, or coloboma and other neurological defects such as epilepsy. To date, the causal relationship between SOX2 abnormalities and non-syndromic HH remains speculative. Here, we identified a nonsense mutation of SOX2 in a male patient clinically diagnosed with non-syndromic HH. The patient had epilepsy but no additional clinical features. Ophthalmological examination revealed no abnormalities except for decreased thickness of the retinal nerve fiber layer. Audiometry showed mild sensorineural hearing impairment of both ears. Hormonal evaluation suggested isolated gonadotropin deficiency. Next-generation sequencing-based mutation screening of 13 major causative genes for HH identified a p.Lys35∗ mutation in SOX2 and excluded pathogenic mutations in other tested genes. The p.Lys35∗ mutation appeared to encode a non-functioning SOX2 protein that lacks 283 of 317 amino acids. The SOX2 mutation was absent in the maternal DNA sample, while a paternal sample was unavailable for sequence analysis. These results expand the clinical consequences of SOX2 haploinsufficiency to include non-syndromic HH. Systematic mutation screening using a next-generation sequencer and detailed evaluation of nonspecific ocular/neurological features may help identify SOX2 mutation-positive individuals among HH patients.

Guidance of Medical Care for Familial Exudative Vitreoretinopathy：Research on Rare and Intractable Diseases, Health and Labour Sciences Research Grants.

Familial exudative vitreoretinopathy is a hereditary insufficiency of retinal vascularture, which manifests a variety of vitreoretinal abnormalities, including nonvascularlized retina, abnormality of retinal vessel growing, dragged retina, retinal folds and total retinal detachment. While causative genes have been identified, cases are often sporadic. Periodic examination is necessary to find recurrence of the disease and late complications, including rhegmatogenous retinal detachment, cataract and glaucoma.

Successful scleral buckling of late-onset visual decrease in eye with retinal folds.

PURPOSE: To describe the outcome of scleral buckling to treat radial retinal folds (RFs) that caused a late-onset and sudden visual decrease with impairment of the fovea. METHODS: This is an observational case report. Ophthalmic examinations were performed preoperatively and postoperatively and included measurement of the best-corrected visual acuity (BCVA), fundus examination, fluorescein angiography, focal macular electroretinography (FM-ERG), and spectral-domain optical coherence tomography (OCT). RESULTS: A patient, whose case was reported previously, had a superonasal retinal detachment with a dislocated fovea and good BCVA in her right eye and a sustained BCVA of 40/50 by age 17 years and 3 months. The BCVA decreased suddenly to 20/200 at age 17 years and 11 months. Fundus examinations showed micro-dislocation of the fovea to the RFs and narrowing of the RFs compared with the previous report. FM-ERG showed an almost extinguished response, and OCT images showed abnormalities of the outer nuclear and photoreceptor layers. Encircling and radial scleral buckling was performed. Four months postoperatively, the BCVA improved to 30/50, which corresponded to the recovery of the FM-ERG response and findings on the OCT images. One year and 3 months postoperatively, the BCVA recovered to 35/50 with repositioning of the fovea. CONCLUSIONS: Simultaneous encircling and radial scleral buckling resulted in the recovery of both retinal function and structure in the current case and is a useful surgical option to treat late-onset progressive RFs due to intensification of traction.

Abnormal traction of the vitreous detected by swept-source optical coherence tomography is related to the maculopathy associated with optic disc pits.

BACKGROUND: Maculopathy associated with optic disc pits (ODP), which sometimes causes severe visual loss, usually appears in late childhood or early adulthood. However, it has long been unclear how the disease begins to develop at these ages. We evaluated the relationship between vitreous structure and maculopathy associated with ODP. METHODS: Six patients (seven eyes) with ODP were diagnosed between July 1990 and May 2013. Fundus photographs and swept-source optical coherence tomography (SS-OCT) images were evaluated retrospectively, and the vitreous at the vitreoretinal interface was visualized by reconstructing three-dimensional SS-OCT images. Vitrectomy was performed in the eyes with maculopathy. RESULTS: Among the six patients, five had ODP in one eye each and one patient had bilateral ODP. The pits were mainly located in the temporal quadrant, and maculopathy, including retinoschisis and retinal detachment, was detected in five eyes associated only with the temporal pits. A flat retinal detachment was observed in four eyes and identified within the vascular arcade except in one eye. A posterior precortical vitreous pocket (PPVP) was observed in all eyes except in one eye without maculopathy. Reconstructing images from SS-OCT showed the vitreoretinal interface abnormalities around the optic disc and the macular area in all eyes, which was completely different from the vitreoretinal interface in the normal pediatric eye. Vitrectomy was performed in four eyes with retinal detachment to resect the abnormal vitreous traction. Posterior vitreous detachment was created in two eyes. Retinal reattachment was achieved in three eyes, and subretinal fluid receded in one eye. The visual acuity improved in all four eyes. CONCLUSIONS: Abnormal traction of the vitreous due to an abnormality of the vitreoretinal interface, which may be strengthened by the development of a PPVP, generates the maculopathy associated with ODP.

Outer retinal deformity detected by optical coherence tomography in eyes with foveal hypoplasia.

PURPOSE: To investigate the relationship between vision and foveal maturity, especially in foveal hypoplasia exhibiting severe structural immaturity. METHODS: This retrospective observational case series included 42 eyes of 23 patients (mean age, 7.0 ± 5.0 years; 9 patients with foveal hypoplasia as an isolated entity and 14 patients with aniridia). A complete ophthalmic examination included measurement of best-corrected visual acuity (BCVA) and spectral-domain optical coherence tomography (SD-OCT). The sensory retina, ganglion cell complex (GCC), and outer retinal layers, including Henle's fiber layer (HFL), were measured and analyzed. RESULTS: Using SD-OCT images, eyes were classified as having a differentiated (6 eyes), diffuse (19 eyes), or no HFL (17 eyes), based on the appearance of the HFL around the foveal region. The logMAR BCVA was significantly worse (p < 0.0001) in eyes with diffuse HFL and those with no HFL than in those with differentiated HFL. Outer retinal thickness (outer plexiform layer + HFL + outer nuclear layer) was less (p = 0.0051) in eyes with no HFL than in those with differentiated HFL. The logMAR BCVA, GCC thickness, and outer retinal thickness in eyes with foveal hypoplasia with aniridia were significantly worse (p = 0.0083), thicker (p = 0.0039), and thinner (p = 0.0001), respectively, than in eyes with foveal hypoplasia as an isolated entity. CONCLUSIONS: In eyes with foveal hypoplasia with severe structural immaturity, diffuse HFL or no HFL was associated with worse vision. There was greater foveal immaturity in eyes with foveal hypoplasia with aniridia compared with foveal hypoplasia as an isolated entity.

Derivation of human differential photoreceptor cells from adult human dermal fibroblasts by defined combinations of CRX, RAX, OTX2 and NEUROD.

Redirecting differentiation of somatic cells by over-expression of transcription factors is a promising approach for regenerative medicine, elucidation of pathogenesis and development of new therapies. We have previously defined a transcription factor combination, that is, CRX, RAX and NEUROD, that can generate photosensitive photoreceptor cells from human iris cells. Here, we show that human dermal fibroblasts are differentiated to photoreceptor cells by the same transcription factor combination as human iris cells. Transduction of a combination of the CRX, RAX and NEUROD genes up-regulated expression of the photoreceptor-specific genes, recoverin, blue opsin and PDE6C, in all three strains of human dermal fibroblasts that were tested. Additional OTX2 gene transduction increased up-regulation of the photoreceptor-specific genes blue opsin, recoverin, S-antigen, CNGB3 and PDE6C. Global gene expression data by microarray analysis further showed that photoreceptor-related functional genes were significantly increased in induced photoreceptor cells. Functional analysis, that is, patch-clamp recordings, clearly revealed that induced photoreceptor cells from fibroblasts responded to light. Both the NRL gene and the NR2E3 gene were endogenously up-regulated in induced photoreceptor cells, implying that exogenous CRX, RAX, OTX2 and NEUROD, but not NRL, are sufficient to generate rod photoreceptor cells.

Two-step transplantation for primary hyperoxaluria: a winning strategy to prevent progression of systemic oxalosis in early onset renal insufficiency cases.

Several transplant strategies for PH1 have been proposed, and LT is performed to correct the metabolic defects. The patients with PH1 often suffer from ESRD and require simultaneous LKT, which leads to a long wait due to the shortage of suitable organ donors. Five patients with PH1 underwent LDLT at our institute. Three of the five patients were under dialysis before LDLT, while the other two patients were categorized as CKD stage 3. An isolated LDLT was successfully performed in all but our first case, who had complicated postoperative courses and consequently died due to sepsis after retransplantation. The renal function of the patients with CKD stage 3 was preserved after LDLT. On the other hand, our second case with ESRD underwent successful LDKT six months after LDLT, and our infant case is waiting for the subsequent KT without any post-LDLT complications after the early establishment of PD. In conclusion, a two-step transplant strategy may be needed as a life-saving option for patients with PH1 and may be possible even in small infants with systemic oxalosis. While waiting for a subsequent KT, an early resumption of PD should be considered from the perspective of the long-term requirement of RRT.

Mutation spectrum and phenotypic variation in nine patients with SOX2 abnormalities.

Multiple mutations in SOX2 have been identified in patients with ocular anomalies and/or pituitary dysfunction. Here, we identified SOX2 abnormalities in nine patients. The molecular defects included one missense, one nonsense and four frameshift mutations, and three submicroscopic deletions involving SOX2. Three of the six mutations and all deletions were hitherto unreported. The breakpoints determined in one deletion were located within Alu repeats and accompanied by an overlap of 11 bp. Three of the six mutations encoded SOX2 proteins that lacked in vitro transactivation activity for the HESX1 promoter, whereas the remaining three generated proteins with ∼15-∼20% of transactivation activity. All cases manifested ocular anomalies of various severities, together with several complications including arachnoid cyst and hamartoma. There was no apparent correlation between the residual activity and clinical severity. The results indicate that molecular defects in SOX2 are highly variable and include Alu repeat-mediated genomic rearrangements. Our data provide further evidence for wide phenotypic variation of SOX2 abnormalities and the lack of genotype-phenotype correlation in patients carrying SOX2 lesions.

Identification of a novel missense mutation of MAF in a Japanese family with congenital cataract by whole exome sequencing: a clinical report and review of literature.

Congenital cataracts are the most important cause of severe visual impairment in infants. Genetic factors contribute to the disease development and 29 genes are known to cause congenital cataracts. Identifying the genetic cause of congenital cataracts can be difficult because of genetic heterogeneity. V-maf avian musculoaponeurotic fibrosarcoma oncogene homolog (MAF) encodes a basic region/leucine zipper transcription factor that plays a key role as a regulator of embryonic lens fiber cell development. MAF mutations have been reported to cause juvenile-onset pulverulent cataract, microcornea, iris coloboma, and other anterior segment dysgenesis. We report on six patients in a family who have congenital cataracts were identified MAF mutation by whole exome sequencing (WES). The heterozygous MAF mutation Q303L detected in the present family occurs in a well conserved glutamine residue at the basic region of the DNA-binding domain. All affected members showed congenital cataracts. Three of the six members showed microcornea and one showed iris coloboma. Congenital cataracts with MAF mutation exhibited phenotypically variable cataracts within the family. Review of the patients with MAF mutations supports the notion that congenital cataracts caused by MAF mutations could be accompanied by microcornea and/or iris coloboma. WES is a useful tool for detecting disease-causing mutations in patients with genetically heterogeneous conditions.

Retinal hemorrhages and damages from tractional forces associated with infantile abusive head trauma evaluated by wide-field fundus photography.

We evaluated the distribution and types of retinal hemorrhages (RHs) and other damages in eyes with abusive head trauma (AHT). This retrospective, consecutive case series of AHT and non-AHT conditions involved 54 children with AHT, 43 children with head bruises, and 49 children with blunt eye trauma, each of non-AHT supported by reliable witness accounts. RHs and other damage were evaluated using ophthalmoscopy and wide-field fundus photography. A variety of RH types and other damage were identified in the AHT group but not in the non-AHT group. RHs in AHT extended from the posterior pole to the far periphery in 77% of eyes and on/near the veins in 86% and arteries in 85%, most of which were in the far periphery. Retinoschisis, white-dot lesions, and retinal folds were seen even in the far periphery. RHs on/near the veins and arteries, retinoschisis, and retinal folds suggest a traumatic mechanism of the tractional force of the vitreous that is attached to the entire retinal surface. Identifying the distribution and arterio and venous origins of RHs is a key factor in determining the association with trauma. Thus, wide-field fundus photography is useful to record and evaluate the origin of the RHs and other retinal damage.

Modeling of Retina and Optic Nerve Ischemia-Reperfusion Injury through Hypoxia-Reoxygenation in Human Induced Pluripotent Stem Cell-Derived Retinal Ganglion Cells.

Retinal ganglion cells (RGCs) are specialized projection neurons that constitute part of the retina, and the death of RGCs causes various eye diseases, but the mechanism of RGC death is still unclear. Here, we induced cell death in human induced pluripotent stem cell (hiPSC)-derived RGC-rich retinal tissues using hypoxia-reoxygenation in vitro. Flow cytometry, immunochemistry, and Western blotting showed the apoptosis and necrosis of RGCs under hypoxia-reoxygenation, and they were rescued by an apoptosis inhibitor but not by a necrosis inhibitor. This revealed that the cell death induced in our model was mainly due to apoptosis. To our knowledge, this is the first model to reproduce ischemia-reperfusion in hiPSC-derived RGCs. Thus, the efficacy of apoptosis inhibitors and neuroprotective agents can be evaluated using this model, bringing us closer to clinical applications.