Cone cell dysfunction attenuates retinal neovascularization in oxygen-induced retinopathy mouse model

Aberrant neovascularization is the most common feature in retinopathy of prematurity (ROP), which leads to the retinal detachment and visual defects in neonates with a low gestational age eventually. Understanding the regulation of inappropriate angiogenic signaling benefits individuals at-risk. Recently, neural activity originating from the specific neural activity has been considered to contribute to retinal angiogenesis. Here, we explored the impact of cone cell dysfunction on oxygen-induced retinopathy (OIR), a mouse model commonly employed to understand retinal diseases associated with abnormal blood vessel growth, using the Gnat2cpfl3 (cone photoreceptor function loss-3) strain of mice (regardless of the sex), which is known for its inherent cone cell dysfunction. We found that the retinal avascular area, hypoxic area, and neovascular area were significantly attenuated in Gnat2cpfl3 OIR mice compared to those in C57BL/6 OIR mice. Moreover, the HIF-1α/VEGF axis was also reduced in Gnat2cpfl3 OIR mice. Collectively, our results indicated that cone cell dysfunction, as observed in Gnat2cpfl3 OIR mice, leads to attenuated retinal neovascularization. This finding suggests that retinal neural activity may precede and potentially influence the onset of pathological neovascularization.

Mitochondrial transplantation attenuates oligomeric amyloid-beta-induced mitochondrial dysfunction and tight junction protein destruction in retinal pigment epithelium

Transplantation of mitochondria derived from mesenchymal stem cells (MSCs) has emerged as a new treatment method to improve mitochondrial dysfunction and alleviate cell impairment. Interest in using extrinsic mitochondrial transplantation as a therapeutic approach has been increasing because it has been confirmed to be effective in treating various diseases related to mitochondrial dysfunction, including ischemia, cardiovascular disease, and toxic damage. To support this application, we conducted an experiment to deliver external mitochondria to retinal pigment epithelial cells treated with oligomeric amyloid-beta (oAβ). Externally delivered amyloid-beta internalizes into cells and interacts with mitochondria, resulting in mitochondrial dysfunction and intracellular damage, including increased reactive oxygen species and destruction of tight junction proteins. Externally delivered mitochondria were confirmed to alleviate mitochondrial dysfunction and tight junction protein disruption as well as improve internalized oAβ clearance. These results were also confirmed in a mouse model in vivo. Overall, these findings indicate that the transfer of external mitochondria isolated from MSCs has potential as a new treatment method for age-related macular degeneration, which involves oAβ-induced changes to the retinal pigment epithelium.

Activation of Lysosomal Function Ameliorates Amyloid-β-Induced Tight Junction Disruption in the Retinal Pigment Epithelium

Accumulation of pathogenic amyloid-β disrupts the tight junction of retinal pigment epithelium (RPE), one of its senescence-like structural alterations. In the clearance of amyloid-β, the autophagy-lysosome pathway plays the crucial role. In this context, mammalian target of rapamycin (mTOR) inhibits the process of autophagy and lysosomal degradation, acting as a potential therapeutic target for age-associated disorders. However, efficacy of targeting mTOR to treat age-related macular degeneration remains largely elusive. Here, we validated the therapeutic efficacy of the mTOR inhibitors, Torin and PP242, in clearing amyloid-β by inducing the autophagy-lysosome pathway in a mouse model with pathogenic amyloid-β with tight junction disruption of RPE, which is evident in dry age-related macular degeneration. High concentration of amyloid-β oligomers induced autophagy-lysosome pathway impairment accompanied by the accumulation of p62 and decreased lysosomal activity in RPE cells. However, Torin and PP242 treatment restored the lysosomal activity via activation of LAMP2 and facilitated the clearance of amyloid-β in vitro and in vivo. Furthermore, clearance of amyloid-β by Torin and PP242 ameliorated the tight junction disruption of RPE in vivo. Overall, our findings suggest mTOR inhibition as a new therapeutic strategy for the restoration of tight junctions in age-related macular degeneration.

Allelic hierarchy for USH2A influences auditory and visual phenotypes in South Korean patients

When medical genetic syndromes are influenced by allelic hierarchies, mutant alleles have distinct effects on clinical phenotypes. Genotype-phenotype correlations for Usher syndrome type 2 (USH2) suggest that the USH2A gene exhibits an allelic hierarchy. Here, we analyzed the phenotypes and genotypes of 16 South Korean patients with USH2A biallelic variants to investigate an allelic hierarchy from audiological and ophthalmological perspectives. Using whole exome and genome sequencing, 18 mutant alleles, including 4 novel alleles, were identified and implicated in USH2A-related disorders. Truncated alleles were linked to earlier onset of subjective hearing loss and more severe thresholds; biallelic truncated alleles had more severe effects. Truncated alleles were also associated with retinal structure degeneration and severe functional deterioration. However, younger patients (aged < 16 years) did not exhibit overt retinitis pigmentosa even when they had biallelic truncated alleles, suggesting that USH2A-related USH2 can mimic nonsyndromic hearing loss. For truncated alleles, there was a clear correlation between mean hearing threshold and 30-Hz flicker electroretinography implicit time. This study provides the first evidence of an USH2A-related allelic hierarchy among South Korean patients; our data yield valuable insights concerning the natural courses of clinical phenotypes and how genotype-based therapies may be used.

Inhibition of protein arginine deiminase II suppresses retinoblastoma in orthotopic transplantation in mice

Chemotherapies are used for treating retinoblastoma; however, numerous patients suffer from recurrence or symptoms due to chemotherapy, which emphasizes the need for alternative therapeutic strategies. The present study demonstrated that protein arginine deiminase Ⅱ (PADI2) was highly expressed in human and mouse retinoblastoma tissues due to the overexpression of E2 factor (E2F). By inhibiting PADI2 activity, the expression of phosphorylated AKT was reduced, and cleaved poly (ADP‑ribose) polymerase level was increased, leading to induced apoptosis. Similar results were obtained in orthotopic mouse models with reduced tumor volumes. In addition, BB‑Cl‑amidine showed low toxicity in vivo. These results suggested that PADI2 inhibition has potential clinical translation. Furthermore, the present study highlights the potential of epigenetic approaches to target RB1‑deficient mutations at the molecular level. The current findings provide new insights into the importance of retinoblastoma intervention by managing PADI2 activity according to the treatment of specific inhibitors and depletion approaches in vitro and in orthotopic mouse models.

Enhancement of Gene Editing and Base Editing with Therapeutic Ribonucleoproteins through In Vivo Delivery Based on Absorptive Silica Nanoconstruct

Key to the widespread and secure application of genome editing tools is the safe and effective delivery of multiple components of ribonucleoproteins (RNPs) into single cells, which remains a biological barrier to their clinical application. To overcome this issue, a robust RNP delivery platform based on a biocompatible sponge-like silica nanoconstruct (SN) for storing and directly delivering therapeutic RNPs, including Cas9 nuclease RNP (Cas9-RNP) and base editor RNP (BE-RNP) is designed. Compared with commercialized material such as lipid-based methods, up to 50-fold gene deletion and 10-fold base substitution efficiency is obtained with a low off-target efficiency by targeting various cells and genes. In particular, gene correction is successfully induced by SN-based delivery through intravenous injection in an in vivo solid-tumor model and through subretinal injection in mouse eye. Moreover, because of its low toxicity and high biodegradability, SN has negligible effect on cellular function of organs. As the engineered SN can overcome practical challenges associated with therapeutic RNP application, it is strongly expected this platform to be a modular RNPs delivery system, facilitating in vivo gene deletion and editing.

Application of Base Editor-Mediated Genome Editing in Mouse Retina

Base editor is a newly developed genome editing technology that enables conversion of single nucleotides without DNA double-strand breaks (DSB) and maintains a low rate of insertion-deletion (INDEL) errors. With these flexibility and safety, base editor has been widely used in many fields, including inherited retinal disease. The majority of retinal genome editing requires intravitreal and subretinal injection delivery of the therapeutic vector in order to transduce the target cells. Here, we provide an application guide of base editor as performed in the mouse retina.

Twenty-Year Retrospective Study of Post-Enucleation Chemotherapy in High-Risk Patients with Unilateral Retinoblastoma

Primary enucleation is a life-saving treatment for advanced intraocular retinoblastoma, particularly in patients with poor visual potential and functional contralateral eyes. This single-center study presents the treatment outcomes of patients with unilateral retinoblastoma who received primary enucleation and adjuvant chemotherapy with cyclophosphamide, vincristine, doxorubicin, and intrathecal methotrexate (CVDM) between 2000 and 2020. Twenty patients were enrolled in the study. The median age at diagnosis was 26 months (range, 1-45). Eighteen patients (90%) were in group E and two (10%) were in group D, according to the intraocular classification of retinoblastoma guidelines. Excluding one patient with an inadequate specimen, 19 patients (95%) had optic nerve involvement (ONI) at least up to the lamina cribrosa. Eight patients (40%) had choroidal invasion in addition to ONI. Two patients (10%) were surgical resection margin positive. The overall and event-free survival rates were 100% and 95%, respectively, for a median follow-up duration of 102.24 months (range 24.2-202.9). There were no relapses or deaths due to any cause, but one patient developed secondary rhabdomyosarcoma 99.6 months after chemotherapy. Treatment was well tolerated, with minimal hematotoxicity and hepatotoxicity. CVDM as a post-enucleation chemotherapy for advanced intraocular retinoblastoma has excellent outcomes with tolerable toxicity. However, in line with updated treatment trends, further risk stratification and lowering the treatment intensity should be considered. Continued long-term follow-up is required to further determine late effects.

Establishment and Characterization of Carboplatin-Resistant Retinoblastoma Cell Lines

Carboplatin-based chemotherapy is the primary treatment option for the management of retinoblastoma, an intraocular malignant tumor observed in children. The aim of the present study was to establish carboplatin-resistant retinoblastoma cell lines to facilitate future research into the treatment of chemoresistant retinoblastoma. In total, two retinoblastoma cell lines, Y79 and SNUOT-Rb1, were treated with increasing concentrations of carboplatin to develop the carboplatin-resistant retinoblastoma cell lines (termed Y79/CBP and SNUOT-Rb1/CBP, respectively). To verify resistance to carboplatin, the degree of DNA fragmentation and the expression level of cleaved caspase-3 were evaluated in the cells, following carboplatin treatment. In addition, the newly developed carboplatin-resistant retinoblastoma cells formed in vivo intraocular tumors more effectively than their parental cells, even after the intravitreal injection of carboplatin. Interestingly, the proportion of cells in the G0/G1 phase was higher in Y79/CBP and SNUOT-Rb1/CBP cells than in their respective parental cells. In line with these data, the expression levels of cyclin D1 and cyclin D3 were decreased, whereas p18 and p27 expression was increased in the carboplatin-resistant cells. In addition, the expression levels of genes associated with multidrug resistance were increased. Thus, these carboplatin-resistant cell lines may serve as a useful tool in the study of chemoresistance in retinoblastoma and for the development potential therapeutics.

In vivo application of base and prime editing to treat inherited retinal diseases

Inherited retinal diseases (IRDs) are vision-threatening retinal disorders caused by pathogenic variants of genes related to visual functions. Genomic analyses in patients with IRDs have revealed pathogenic variants which affect vision. However, treatment options for IRDs are limited to nutritional supplements regardless of genetic variants or gene-targeting approaches based on antisense oligonucleotides and adeno-associated virus vectors limited to targeting few genes. Genome editing, particularly that involving clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 technologies, can correct pathogenic variants and provide additional treatment opportunities. Recently developed base and prime editing platforms based on CRISPR-Cas9 technologies are promising for therapeutic genome editing because they do not employ double-stranded breaks (DSBs), which are associated with P53 activation, large deletions, and chromosomal translocations. Instead, using attached deaminases and reverse transcriptases, base and prime editing efficiently induces specific base substitutions and intended genetic changes (substitutions, deletions, or insertions), respectively, without DSBs. In this review, we will discuss the recent in vivo application of CRISPR-Cas9 technologies, focusing on base and prime editing, in animal models of IRDs.

The Global Retinoblastoma Outcome Study: a prospective, cluster-based analysis of 4064 patients from 149 countries

Background

Retinoblastoma is the most common intraocular cancer worldwide. There is some evidence to suggest that major differences exist in treatment outcomes for children with retinoblastoma from different regions, but these differences have not been assessed on a global scale. We aimed to report 3-year outcomes for children with retinoblastoma globally and to investigate factors associated with survival.

Methods

We did a prospective cluster-based analysis of treatment-naive patients with retinoblastoma who were diagnosed between Jan 1, 2017, and Dec 31, 2017, then treated and followed up for 3 years. Patients were recruited from 260 specialised treatment centres worldwide. Data were obtained from participating centres on primary and additional treatments, duration of follow-up, metastasis, eye globe salvage, and survival outcome. We analysed time to death and time to enucleation with Cox regression models.

Findings

The cohort included 4064 children from 149 countries. The median age at diagnosis was 23·2 months (IQR 11·0–36·5). Extraocular tumour spread (cT4 of the cTNMH classification) at diagnosis was reported in five (0·8%) of 636 children from high-income countries, 55 (5·4%) of 1027 children from upper-middle-income countries, 342 (19·7%) of 1738 children from lower-middle-income countries, and 196 (42·9%) of 457 children from low-income countries. Enucleation surgery was available for all children and intravenous chemotherapy was available for 4014 (98·8%) of 4064 children. The 3-year survival rate was 99·5% (95% CI 98·8–100·0) for children from high-income countries, 91·2% (89·5–93·0) for children from upper-middle-income countries, 80·3% (78·3–82·3) for children from lower-middle-income countries, and 57·3% (52·1-63·0) for children from low-income countries. On analysis, independent factors for worse survival were residence in low-income countries compared to high-income countries (hazard ratio 16·67; 95% CI 4·76–50·00), cT4 advanced tumour compared to cT1 (8·98; 4·44–18·18), and older age at diagnosis in children up to 3 years (1·38 per year; 1·23–1·56). For children aged 3–7 years, the mortality risk decreased slightly (p=0·0104 for the change in slope).

Interpretation

This study, estimated to include approximately half of all new retinoblastoma cases worldwide in 2017, shows profound inequity in survival of children depending on the national income level of their country of residence. In high-income countries, death from retinoblastoma is rare, whereas in low-income countries estimated 3-year survival is just over 50%. Although essential treatments are available in nearly all countries, early diagnosis and treatment in low-income countries are key to improving survival outcomes.

Funding

Queen Elizabeth Diamond Jubilee Trust.

Current and potential use of fresh frozen cadaver in surgical training and anatomical education

As surgical procedures continue to be more complex, the need for more effective training in anatomy has increased. The study of anatomy plays a significant role in the understanding of the human body as well as in basic and advanced clinical training. Among the different cadaver models, fresh frozen cadavers (FFCs) are known for their realistic tissue quality. The purpose of this article was to review and summarize the preparation procedures for and reported cases involving FFCs. PubMed, Scopus, Medline, and Web of Science were searched for relevant studies. The preparation procedures were divided into five steps: washing, irrigation, freezing, defrosting, and arterial infusion. Not all steps were reported to be mandatory, but omitting one or more could result in a loss of quality. FFCs were reported to be used for various purposes: undergraduate education, general surgery training, vascular surgery training, minimal access surgery (laparoscopic surgery) training, and microsurgery training. In all categories, expert opinions and statistical analyses indicated successful outcomes. The reasons for high satisfaction with FFCs included realistic texture, capability of reenacting actual operations, and accuracy of anatomical locations. The results also revealed the importance and advantages of the dissection courses in surgical training. Since the direct comparison between cadaver models is insufficient, future studies regarding this topic are deemed necessary. In addition, it would be advantageous to develop methods to improve FFC quality, or ideas to optimize this model for certain purposes.

Ocular microbiota promotes pathological angiogenesis and inflammation in sterile injury-driven corneal neovascularization

Microbiota promotes or inhibits the pathogenesis of a range of immune-mediated disorders. Although recent studies have elucidated the role of gut microbiota in ocular disease, the effect of ocular microbiota remains unclear. Herein, we explored the role of ocular commensal bacteria in non-infectious corneal inflammation and angiogenesis in a mouse model of suture-induced corneal neovascularization. Results revealed that the ocular surface harbored a microbial community consisting mainly of Actinobacteria, Firmicutes and Proteobacteria. Elimination of the ocular commensal bacteria by oral broad-spectrum antibiotics or topical fluoroquinolone significantly suppressed corneal inflammation and neovascularization. Disease amelioration was associated with reduced numbers of CD11b⁺Ly6C⁺ and CD11b⁺Ly6G⁺ myeloid cells, not Foxp3⁺ regulatory T cells, in the spleen, blood, and draining lymph nodes. Therapeutic concentrations of fluoroquinolone, however, did not directly affect immune cells or vascular endothelial cells. In addition, data from a clinical study showed that antibiotic treatment in combination with corticosteroids, as compared with corticosteroid monotherapy, induced faster remission of corneal inflammation and new vessels in pediatric patients with non-infectious marginal keratitis. Altogether, our findings demonstrate a pathogenic role of ocular microbiota in non-infectious inflammatory disorders leading to sight-threatening corneal neovascularization, and suggest a therapeutic potential of targeting commensal microbes in treating ocular inflammation.

The impact of the modified schedules of anatomy education on students' performance and satisfaction: Responding to COVID-19 pandemic in South Korea

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic substantially undermined medical education and healthcare systems. Owing to the pandemic in South Korea, most medical schools needed to be flexible when conducting online and offline classes, but the guidelines did not reflect the specificity of medical schools. This study described the impact of modified anatomy education schedules at the Seoul National University College of Medicine (SNUCM) on students' academic performance and satisfaction.

METHODS

Anatomy education in SNUCM is divided into three regional units (the upper and lower limbs, trunk, and head and neck). Owing to the COVID-19 pandemic, the schedule was mixed with simultaneous and rotating schedules. The authors conducted exceptions for online lectures, cadaver dissections, and written and practical examinations in three classes of approximately 50 students each. Furthermore, the authors assessed students' performance using three sets of written and practical examinations, and students completed a questionnaire regarding modified anatomy laboratory schedules.

RESULTS

Despite the pandemic events in Seoul and South Korea during the laboratory sessions, all sessions were completed without any confirmed COVID-19 cases among the students, faculty, and staff. Most of the scores on the written and practical examinations significantly decreased in 2020 compared to those in 2019. However, in the trunk session that used the virtual anatomy application, the score on the practical examination in 2020 was significantly higher than that in 2019. Over 70% (79 and 77 out of 105 respondents on the upper and lower limbs and trunk, respectively) and 53% (55/105) students reported that there were no significant difficulties in studying anatomy in a face-to-face laboratory.

CONCLUSIONS

In conclusion, an adequate education program for cadaver dissection should be developed and provided to overcome the pandemic restrictions. The study findings could serve as a reference for anatomy education during the COVID-19 pandemic.

Self-Plugging Microneedle (SPM) for Intravitreal Drug Delivery

Intravitreal injection (IVI) is a common technology which is used to treat ophthalmic diseases inside eyeballs by delivering various drugs into the vitreous cavity using hypodermic needles. However, in some cases, there are possible side effects such as ocular tissue damage due to repeated injection or eyeball infection through the hole created during the needle retraction process. The best scenario of IVI is a one-time injection of drugs without needle retraction, keeping the system of the eyeball closed. Microneedles (MNs) have been applied to ocular tissues over 10 years, and no serious side effects on ocular tissue due to MN injection have been reported. Therefore, a self-plugging MN (SPM) is developed to perform intraocular drug delivery and to seal the scleral puncture simultaneously. The SPMs are fabricated by a thermal drawing process and then coated with a polymeric carrier of drugs and a hydrogel-based scleral plugging component. Each coated functional layer is characterized and demonstrated by in vitro and ex vivo experiments. Finally, in vivo tests using a porcine model confirms prompt sealing of SPM and sustained intraocular drug delivery.

Specific ablation of PDGFRβ-overexpressing pericytes with antibody-drug conjugate potently inhibits pathologic ocular neovascularization in mouse models

BACKGROUND

Crosstalk between pericytes and endothelial cells is critical for ocular neovascularization. Endothelial cells secrete platelet-derived growth factor (PDGF)-BB and recruit PDGF receptor β (PDGFRβ)-overexpressing pericytes, which in turn cover and stabilize neovessels, independent of vascular endothelial growth factor (VEGF). Therapeutic agents inhibiting PDGF-BB/PDGFRβ signaling were tested in clinical trials but failed to provide additional benefits over anti-VEGF agents. We tested whether an antibody-drug conjugate (ADC) - an engineered monoclonal antibody linked to a cytotoxic agent - could selectively ablate pericytes and suppress retinal and choroidal neovascularization.

METHODS

Immunoblotting, flow cytometry, cell viability test, and confocal microscopy were conducted to assess the internalization and cytotoxic effect of ADC targeting mPDGFRβ in an in vitro setting. Immunofluorescence staining of whole-mount retinas and retinal pigment epithelium-choroid-scleral complexes, electroretinography, and OptoMotry test were used to evaluate the effect and safety of ADC targeting mPDGFRβ in the mouse models of pathologic ocular neovascularization.

RESULTS

ADC targeting mPDGFRβ is effectively internalized into mouse brain vascular pericytes and showed significant cytotoxicity compared with the control ADC. We also show that specific ablation of PDGFRβ-overexpressing pericytes using an ADC potently inhibits pathologic ocular neovascularization in mouse models of oxygen-induced retinopathy and laser-induced choroidal neovascularization, while not provoking generalized retinal toxicity.

CONCLUSION

Our results suggest that removing PDGFRβ-expressing pericytes by an ADC targeting PDGFRβ could be a potential therapeutic strategy for pathologic ocular neovascularization.

KAI1(CD82) is a key molecule to control angiogenesis and switch angiogenic milieu to quiescent state

BACKGROUND

Little is known about endogenous inhibitors of angiogenic growth factors. In this study, we identified a novel endogenous anti-angiogenic factor expressed in pericytes and clarified its underlying mechanism and clinical significance.

METHODS

Herein, we found Kai1 knockout mice showed significantly enhanced angiogenesis. Then, we investigated the anti-angiogenic roll of Kai1 in vitro and in vivo.

RESULTS

KAI1 was mainly expressed in pericytes rather than in endothelial cells. It localized at the membrane surface after palmitoylation by zDHHC4 enzyme and induced LIF through the Src/p53 pathway. LIF released from pericytes in turn suppressed angiogenic factors in endothelial cells as well as in pericytes themselves, leading to inhibition of angiogenesis. Interestingly, KAI1 had another mechanism to inhibit angiogenesis: It directly bound to VEGF and PDGF and inhibited activation of their receptors. In the two different in vivo cancer models, KAI1 supplementation significantly inhibited tumor angiogenesis and growth. A peptide derived from the large extracellular loop of KAI1 has been shown to have anti-angiogenic effects to block the progression of breast cancer and retinal neovascularization in vivo.

CONCLUSIONS

KAI1 from PC is a novel molecular regulator that counterbalances the effect of angiogenic factors.

High-purity production and precise editing of DNA base editing ribonucleoproteins

Ribonucleoprotein (RNP) complex-mediated base editing is expected to be greatly beneficial because of its reduced off-target effects compared to plasmid- or viral vector-mediated gene editing, especially in therapeutic applications. However, production of recombinant cytosine base editors (CBEs) or adenine base editors (ABEs) with ample yield and high purity in bacterial systems is challenging. Here, we obtained highly purified CBE/ABE proteins from a human cell expression system and showed that CBE/ABE RNPs exhibited different editing patterns (i.e., less conversion ratio of multiple bases to single base) compared to plasmid-encoded CBE/ABE, mainly because of the limited life span of RNPs in cells. Furthermore, we found that off-target effects in both DNA and RNA were greatly reduced for ABE RNPs compared to plasmid-encoded ABE. We ultimately applied NG PAM-targetable ABE RNPs to in vivo gene correction in retinal degeneration 12 (rd12) model mice.

Blockade of mTORC1-NOX signaling pathway inhibits TGF-β1-mediated senescence-like structural alterations of the retinal pigment epithelium

The retinal pigment epithelium (RPE) undergoes characteristic structural changes and epithelial-mesenchymal transition (EMT) during normal aging, which are exacerbated in age-related macular degeneration (AMD). Although the pathogenic mechanisms of aging and AMD remain unclear, transforming growth factor-β1 (TGF-β1) is known to induce oxidative stress, morphometric changes, and EMT as a senescence-promoting factor. In this study, we examined whether intravitreal injection of TGF-β1 into the mouse eye elicits senescence-like morphological alterations in the RPE and if this can be prevented by suppressing mammalian target of rapamycin complex 1 (mTORC1) or NADPH oxidase (NOX) signaling. We verified that intravitreal TGF-β1-induced stress fiber formation and EMT in RPE cells, along with age-associated morphometric changes, including increased variation in cell size and reduced cell density. In RPE cells, exogenous TGF-β1 increased endogenous expression of TGF-β1 and upregulated Smad3-ERK1/2-mTORC1 signaling, increasing reactive oxygen species (ROS) production and EMT. We demonstrated that inhibition of the mTORC1-NOX4 pathway by pretreatment with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), an activator of AMP-dependent protein kinase, or GKT137831, a NOX1/4 inhibitor, decreased ROS generation, prevented stress fiber formation, attenuated EMT, and improved the regularity of the RPE structure in vitro and in vivo. These results suggest that intravitreal TGF-β1 injection could be used as a screening model to investigate the aging-related structural and functional changes to the RPE. Furthermore, the regulation of TGF-β-mTORC1-NOX signaling could be a potential therapeutic target for reducing pathogenic alterations in aged RPE and AMD.

Corneal lymphangiogenesis in dry eye disease is regulated by substance P/neurokinin-1 receptor system through controlling expression of vascular endothelial growth factor receptor 3

PURPOSE

To evaluate the role of substance P (SP)/neurokinin-1 receptor (NK1R) system in the regulation of pathologic corneal lymphangiogenesis in dry eye disease (DED).

METHODS

Immunocytochemistry, angiogenesis assay, and Western blot analysis of human dermal lymphatic endothelial cells (HDLECs) were conducted to assess the involvement of SP/NK1R system in lymphangiogenesis. DED was induced in wild-type C57BL/6 J mice using controlled-environment chamber without scopolamine. Immunohistochemistry, corneal fluorescein staining, and phenol red thread test were used to evaluate the effect of SP signaling blockade in the corneal lymphangiogenesis. The expression of lymphangiogenic factors in the corneal and conjunctival tissues of DED mouse model was quantified by real-time polymerase chain reaction.

RESULTS

NK1R expression and pro-lymphangiogenic property of SP/NK1R system in HDLECs were confirmed by Western blot analysis and angiogenesis assay. Blockade of SP signaling with L733,060, an antagonist of NK1R, or NK1R-targeted siRNA significantly inhibited lymphangiogenesis and expression of vascular endothelial growth factor (VEGF) receptor 3 stimulated by SP in HDLECs. NK1R antagonist also suppressed pathological corneal lymphangiogenesis and ameliorated the clinical signs of dry eye in vivo. Furthermore, NK1R antagonist effectively suppressed the lymphangiogenic factors, including VEGF-C, VEGF-D, and VEGF receptor 3 in the corneal and conjunctival tissues of DED.

CONCLUSIONS

SP/NK1R system promotes lymphangiogenesis in vitro and NK1R antagonism suppresses pathologic corneal lymphangiogenesis in DED in vivo.

Antitumor Activity of Novel Signal Transducer and Activator of Transcription 3 Inhibitors on Retinoblastoma

Signal transducer and activator of transcription 3 (STAT3) is a plausible therapeutic target in the treatment of retinoblastoma, the most common intraocular malignant tumor in children. STAT3, a transcription factor of several genes related to tumorigenesis, is activated in retinoblastoma tumors as well as other cancers. In this study, we investigated the structure-activity relationship of a library of STAT3 inhibitors, including a novel series of derivatives of the previously reported compound with a Michael acceptor (compound 1). We chose two novel STAT3 inhibitors, compounds 11 and 15, from the library based on their inhibitory effects on the phosphorylation and transcription activity of STAT3. These STAT3 inhibitors effectively suppressed the phosphorylation of STAT3 and inhibited the expression of STAT3-related genes CCND1, CDKN1A, BCL2, BCL2L1, BIRC5, MYC, MMP1, MMP9, and VEGFA Intraocularly administered STAT3 inhibitors decreased the degree of tumor formation in the vitreous cavity of BALB/c nude mice of an orthotopic transplantation model. It is noteworthy that compounds 11 and 15 did not induce in vitro and in vivo toxicity on retinal constituent cells and retinal tissues, respectively, despite their potent antitumor effects. We suggest that these novel STAT3 inhibitors be used in the treatment of retinoblastoma. SIGNIFICANCE STATEMENT: The current study suggests the novel STAT3 inhibitors with Michael acceptors possess antitumor activity on retinoblastoma, the most common intraocular cancer in children. Based on detailed structure-activity relationship studies, we found a 4-fluoro and 3-trifluoro analog (compound 11) and a monochloro analog (compound 15) of the parental compound (compound 1) inhibited STAT3 phosphorylation, leading to suppressed retinoblastoma in vitro and in vivo.

Development of New Solitary Retinoblastoma Tumors during and after Chemotherapy

PURPOSE

To review the occurrence of new solitary tumors during and after intravenous chemotherapy against retinoblastoma.

METHODS

From 115 eyes of 78 patients with a diagnosis of intraocular retinoblastoma who underwent intravenous chemotherapy and focal treatment without prior treatment, patient demographics, age at diagnosis, laterality, classification (Reese-Ellsworth and International Classification of Retinoblastoma), and treatment options were recorded. In addition, the occurrence of small tumors during and after chemotherapy was documented with a detailed review of medical records and fundus photographs.

RESULTS

Of a total of 115 eyes of 78 consecutive patients, new solitary tumors were observed in 50 eyes (50 / 115, 43%) of 40 patients (40 / 78, 51%). Multinominal logistic regression analyses showed that age at diagnosis (before 1 year) and vitreal seeding at diagnosis were linked to the development of isolated and miliary tumors, respectively. Kaplan-Meier analyses demonstrated that all small tumors developed with 20 months from the start of chemotherapy. Twenty-eight eyes (28 / 34, 82%) were salvaged with additional focal treatment in 34 eyes with isolated tumors.

CONCLUSIONS

Small tumors were observed during and after chemotherapy against retinoblastoma in patients who underwent intravenous chemotherapy and focal treatment. It is necessary to promptly identify and address small tumors for the preservation of eyeball and vision.

Ocular surface complications of local anticancer drugs for treatment of ocular tumors

Local chemotherapy is increasingly used, either in combination with surgery or as monotherapy, for management of ocular tumors. Yet many of the local chemotherapeutic agents used for ocular tumors are cytotoxic drugs that are frequently associated with toxicities in normal ocular tissues. Understanding and managing these side effects are important because they affect treatment tolerability, outcome and quality of vision. Herein, we review local anticancer drugs administered for the treatment of ocular tumors, with an emphasis on their toxicities to the ocular surface, adnexa and lacrimal drainage system. We provide the underlying mechanisms and management strategies for the ocular side effects. Recent innovations in anticancer immunotherapy and ocular drug delivery systems also are discussed as new potential therapeutic modalities for alleviation of side effects.

Toward the Clinical Application of Therapeutic Angiogenesis Against Pediatric Ischemic Retinopathy

Therapeutic angiogenesis refers to strategies of inducing angiogenesis to treat diseases involving ischemic conditions. Historically, most attempts and achievements have been related to coronary and peripheral artery diseases. In this review, we propose the clinical application of therapeutic angiogenesis for the treatment of pediatric ischemic retinopathy, including retinopathy of prematurity, familial exudative retinopathy, and NDP-related retinopathy. These diseases are all characterized by the reduction of physiological angiogenesis and the following induction of pathological angiogenesis. Therapeutic angiogenesis, which supplements insufficient physiological angiogenesis, may be a therapeutic approach for ischemic conditions. Various molecules and modalities can be utilized to apply therapeutic angiogenesis for the treatment of ischemic retinopathy, as in coronary and peripheral artery diseases. Experiences with cardiovascular diseases provide a useful reference for the further clinical application of therapeutic angiogenesis in pediatric ischemic retinopathy. Recombinant proteins and gene therapy are powerful tools to deliver angiogenic factors to retinal tissues directly. Furthermore, endothelial progenitor or bone marrow-derived cells can be injected into the vitreous cavity of the eye for therapeutic angiogenesis. Intraocular injections are highly promising for the delivery of therapeutics for therapeutic angiogenesis. We expect that therapeutic angiogenesis will be a breakthrough in the treatment of pediatric ischemic retinopathy.

Global Retinoblastoma Presentation and Analysis by National Income Level

Importance

Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale.

Objectives

To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis.

Design, Setting, and Participants

A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017.

Main Outcomes and Measures

Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis.

Results

The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4%) were female. Most patients (n = 3685 [84.7%]) were from low- and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 [62.8%]), followed by strabismus (n = 429 [10.2%]) and proptosis (n = 309 [7.4%]). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 [95% CI, 12.94-24.80], and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 [95% CI, 4.30-7.68]).

Conclusions and Relevance

This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs.

Effect of a Single Intravitreal Bevacizumab Injection on Proteinuria in Patients With Diabetes

Purpose

Proteinuria is the second most common complication after hypertension after systemic administration of bevacizumab. Therefore we aimed to analyze the effect of intravitreal bevacizumab (IVB) injection on proteinuria in patients with diabetes.

Methods

Patients scheduled to receive IVB injection from May 1, 2018, to December 31, 2018, were prospectively enrolled. In total, 53 patients with diabetes (26 with nonproliferative diabetic retinopathy and 27 with proliferative diabetic retinopathy) and 37 patients without diabetes were included. Urine tests were performed within 1 month of and 7 ± 1 days after IVB injection. Urinary protein, creatinine, and albumin concentrations were quantitatively measured, and urinary protein-to-creatinine ratio and urinary albumin-to-creatinine ratio (UACR) were calculated from these data before and after IVB injection.

Results

The mean urinary microalbumin concentrations and urinary protein-to-creatinine ratio were significantly higher in patients with diabetes, both before and after IVB injection. There were no differences between patients with nonproliferative diabetic retinopathy and proliferative diabetic retinopathy. About 80% of patients with diabetes showed improved albuminuria or at least no harmful effect in terms of albuminuria. Patients with deteriorated baseline UACR showed more residual increase in UACR after IVB injection (P < 0.05 in all groups).

Conclusions

Close monitoring of renal function after IVB might be needed in patients with diabetes according to the severity of nephropathy.

Translational Relevance

Our results may provide information regarding the renal function of IVB-treated patients with diabetes.

Thioredoxin-Interacting Protein Promotes Phagosomal Acidification Upon Exposure to Escherichia coli Through Inflammasome-Mediated Caspase-1 Activation in Macrophages

In host defense, it is crucial to maintain the acidity of the macrophage phagosome for effective bacterial clearance. However, the mechanisms governing phagosomal acidification upon exposure to gram-negative bacteria have not been fully elucidated. In this study, we demonstrate that in macrophages exposed to Escherichia coli, the thioredoxin-interacting protein (TXNIP)-associated inflammasome plays a role in pH modulation through the activated caspase-1-mediated inhibition of NADPH oxidase. While there was no difference in early-phase bacterial engulfment between Txnip knockout (KO) macrophages and wild-type (WT) macrophages, Txnip KO macrophages were less efficient at destroying intracellular bacteria in the late phase, and their phagosomes failed to undergo appropriate acidification. These phenomena were associated with reactive oxygen species production and were reversed by treatment with an NADPH oxidase inhibitor or a caspase inhibitor. In line with these results, Txnip KO mice were more susceptible to both intraperitoneally administered E. coli and sepsis induced by cecum ligation and puncture than WT mice. Taken together, this study suggests that the TXNIP-associated inflammasome-caspase-1 axis regulates NADPH oxidase to modulate the pH of the phagosome, controlling bacterial clearance by macrophages.

CRISPR-Cas9-mediated therapeutic editing of Rpe65 ameliorates the disease phenotypes in a mouse model of Leber congenital amaurosis

Leber congenital amaurosis (LCA), one of the leading causes of childhood-onset blindness, is caused by autosomal recessive mutations in several genes including RPE65. In this study, we performed CRISPR-Cas9-mediated therapeutic correction of a disease-associated nonsense mutation in Rpe65 in rd12 mice, a model of human LCA. Subretinal injection of adeno-associated virus carrying CRISPR-Cas9 and donor DNA resulted in >1% homology-directed repair and ~1.6% deletion of the pathogenic stop codon in Rpe65 in retinal pigment epithelial tissues of rd12 mice. The a- and b-waves of electroretinograms were recovered to levels up to 21.2 ± 4.1% and 39.8 ± 3.2% of their wild-type mice counterparts upon bright stimuli after dark adaptation 7 months after injection. There was no definite evidence of histologic perturbation or tumorigenesis during 7 months of observation. Collectively, we present the first therapeutic correction of an Rpe65 nonsense mutation using CRISPR-Cas9, providing new insight for developing therapeutics for LCA.

CRISPR-Pass: Gene Rescue of Nonsense Mutations Using Adenine Base Editors

A nonsense mutation is a substitutive mutation in a DNA sequence that causes a premature termination during translation and produces stalled proteins, resulting in dysfunction of a gene. Although it usually induces severe genetic disorders, there are no definite methods for inducing read through of premature termination codons (PTCs). Here, we present a targeted tool for bypassing PTCs, named CRISPR-pass, that uses CRISPR-mediated adenine base editors. CRISPR-pass, which should be applicable to 95.5% of clinically significant nonsense mutations in the ClinVar database, rescues protein synthesis in patient-derived fibroblasts, suggesting potential clinical utility.

Arg-Leu-Tyr-Glu Suppresses Retinal Endothelial Permeability and Choroidal Neovascularization by Inhibiting the VEGF Receptor 2 Signaling Pathway

Vascular endothelial growth factor (VEGF) plays a pivotal role in pathologic ocular neovascularization and vascular leakage via activation of VEGF receptor 2 (VEGFR2). This study was undertaken to evaluate the therapeutic mechanisms and effects of the tetrapeptide Arg-Leu-Tyr-Glu (RLYE), a VEGFR2 inhibitor, in the development of vascular permeability and choroidal neovascularization (CNV). In cultured human retinal microvascular endothelial cells (HRMECs), treatment with RLYE blocked VEGF-A-induced phosphorylation of VEGFR2, Akt, ERK, and endothelial nitric oxide synthase (eNOS), leading to suppression of VEGF-A-mediated hyper-production of NO. Treatment with RLYE also inhibited VEGF-A-stimulated angiogenic processes (migration, proliferation, and tube formation) and the hyperpermeability of HRMECs, in addition to attenuating VEGF-A-induced angiogenesis and vascular permeability in mice. The anti-vascular permeability activity of RLYE was correlated with enhanced stability and positioning of the junction proteins VE-cadherin, β-catenin, claudin-5, and ZO-1, critical components of the cortical actin ring structure and retinal endothelial barrier, at the boundary between HRMECs stimulated with VEGF-A. Furthermore, intravitreally injected RLYE bound to retinal microvascular endothelium and inhibited laser-induced CNV in mice. These findings suggest that RLYE has potential as a therapeutic drug for the treatment of CNV by preventing VEGFR2-mediated vascular leakage and angiogenesis.

The matricellular protein CCN5 inhibits fibrotic deformation of retinal pigment epithelium

Retinal pigment epithelium (RPE) plays an essential role in maintaining retinal function, and its defect is thought to be critically implicated in various ocular disorders. This study demonstrated that the matricellular protein CCN5 was down-regulated in ARPE-19 cells treated with the pro-fibrotic agent transforming growth factor (TGF)-β. A recombinant adenovirus expressing CCN5 (AdCCN5) was used to restore the level of CCN5 in these cells. AdCCN5 prevented TGF-β-induced fibrotic changes, including disruption of tight junctions, up-regulation of mesenchymal marker proteins, and down-regulation of epithelial marker proteins. In addition, AdCCN5 prevented TGF-β-induced functional defects, including increased migratory activity and reduced phagocytic activity. Notably, AdCCN5 reversed morphological and functional defects pre-established by TGF-β prior to viral infection. The CCN5 level was down-regulated in RPE of 18-month-old Ccl2-/- mice, which exhibited retinal defects. Restoration of the CCN5 level via intravitreal injection of a recombinant adeno-associated virus expressing CCN5 (AAV9-CCN5) normalized the altered expression of mesenchymal, epithelial, and functional marker proteins, as assessed by western blotting and immunohistochemistry. Taken together, these data suggest that down-regulation of CCN5 is associated with fibrotic deformation of RPE under pathological conditions and that restoration of the CCN5 level effectively promotes recovery of deformed RPE.

Targeting tyrosine kinases for treatment of ocular tumors

Uveal melanoma is the most common intraocular primary malignant tumor in adults, and retinoblastoma is the one in children. Current mainstay treatment options include chemotherapy using conventional drugs and enucleation, the total removal of the eyeball. Targeted therapies based on profound understanding of molecular mechanisms of ocular tumors may increase the possibility of preserving the eyeball and the vision. Tyrosine kinases, which modulate signaling pathways regarding various cellular functions including proliferation, differentiation, and attachment, are one of the attractive targets for targeted therapies against uveal melanoma and retinoblastoma. In this review, the roles of both types of tyrosine kinases, receptor tyrosine kinases and non-receptor tyrosine kinases, were summarized in relation with ocular tumors. Although the conventional treatment options for uveal melanoma and retinoblastoma are radiotherapy and chemotherapy, respectively, specific tyrosine kinase inhibitors will enhance our armamentarium against them by controlling cancer-associated signaling pathways related to tyrosine kinases. This review can be a stepping stone for widening treatment options and realizing targeted therapies against uveal melanoma and retinoblastoma.

Interaction between microglia and retinal pigment epithelial cells determines the integrity of outer blood-retinal barrier in diabetic retinopathy

Inner and outer blood-retinal barriers (BRBs), mainly composed of retinal endothelial cells and retinal pigment epithelial (RPE) cells, respectively, maintain the integrity of the retinal tissues. In this study, we aimed to investigate the mechanisms of the outer BRB disruption regarding the interaction between RPE and microglia. In mice with high-fat diet-induced obesity and streptozotocin-induced hyperglycemia, microglia accumulated on the RPE layer, as in those after intravitreal injection of interleukin (IL)-6, which is elevated in ocular fluids of patients with diabetic retinopathy. Although IL-6 did not directly affect the levels of zonula occludens (ZO)-1 and occludin in RPE cells, IL-6 increased VEGFA mRNA in RPE cells to recruit microglial cells. In microglial cells, IL-6 upregulated the mRNA levels of MCP1, MIP1A, and MIP1B, to amplify the recruitment of microglial cells. In this manner, IL-6 modulated RPE and microglial cells to attract microglial cells on RPE cells. Furthermore, IL-6-treated microglial cells produced and secreted tumor necrosis factor (TNF)-α, which activated NF-κB and decreased the levels of ZO-1 in RPE cells. As STAT3 inhibition reversed the effects of IL-6-treated microglial cells on the RPE monolayer in vitro, it reduced the recruitment of microglial cells and the production of TNF-α in RPE tissues in streptozotocin-treated mice. Taken together, IL-6-treated RPE and microglial cells amplified the recruitment of microglial cells and IL-6-treated microglial cells produced TNF-α to disrupt the outer BRB in diabetic retinopathy.

Novel Hypoxia-Inducible Factor 1α (HIF-1α) Inhibitors for Angiogenesis-Related Ocular Diseases: Discovery of a Novel Scaffold via Ring-Truncation Strategy

Ocular diseases featuring pathologic neovascularization are the leading cause of blindness, and anti-VEGF agents have been conventionally used to treat these diseases. Recently, regulating factors upstream of VEGF, such as HIF-1α, have emerged as a desirable therapeutic approach because the use of anti-VEGF agents is currently being reconsidered due to the VEGF action as a trophic factor. Here, we report a novel scaffold discovered through the complete structure-activity relationship of ring-truncated deguelin analogs in HIF-1α inhibition. Interestingly, analog 6i possessing a 2-fluorobenzene moiety instead of a dimethoxybenzene moiety exhibited excellent HIF-1α inhibitory activity, with an IC₅₀ value of 100 nM. In particular, the further ring-truncated analog 34f, which showed enhanced HIF-1α inhibitory activity compared to analog 2 previously reported by us, inhibited in vitro angiogenesis and effectively suppressed hypoxia-mediated retinal neovascularization. Importantly, the heteroatom-substituted benzene ring as a key structural feature of analog 34f was identified as a novel scaffold for HIF-1α inhibitors that can be used in lieu of a chromene ring.

Bispecific anti-mPDGFRβ x cotinine scFv-Cκ-scFv fusion protein and cotinine-duocarmycin can form antibody-drug conjugate-like complexes that exert cytotoxicity against mPDGFRβ expressing cells

Antibody selection for antibody-drug conjugates (ADCs) has traditionally depended on its internalization into the target cell, although ADC efficacy also relies on recycling of the receptor-ADC complex, endo-lysosomal trafficking, and subsequent linker/antibody proteolysis. In this study, we observed that a bispecific anti-murine platelet-derived growth factor receptor beta (mPDGFRβ) x cotinine single-chain variable fragment (scFv)-kappa constant region (C_κ)-scFv fusion protein and cotinine-duocarmycin can form an ADC-like complex to induce cytotoxicity against mPDGFRβ expressing cells. Multiple anti-mPDGFRβ antibody candidates can be produced in this bispecific scFv-C_κ-scFv fusion protein format and tested for their ability to deliver cotinine-conjugated cytotoxic drugs, thus providing an improved approach for antibody selection in ADC development.

Application of genome engineering for treatment of retinal diseases

Genome engineering with clustered regularly interspaced short palindromic repeats (CRISPR) system can be used as a tool to correct pathological mutations or modulate gene expression levels associated with pathogenesis of human diseases. Owing to well-established local administration methods including intravitreal and subretinal injection, it is relatively easy to administer therapeutic genome engineering machinery to ocular tissues for treating retinal diseases. In this context, we have investigated the potential of in vivo genome engineering as a therapeutic approach in the form of ribonucleoprotein or CRISPR packaged in viral vectors. Major issues in therapeutic application of genome engineering include specificity and efficacy according to types of CRISPR system. In addition to previous platforms based on ribonucleoprotein and CRISPRassociated protein 9 derived from Campylobacter jejuni, we evaluated the therapeutic effects of a CRISPR RNA-guided endonuclease derived from Lachnospiraceae bacterium ND2006 (LbCpf1) in regulating pathological angiogenesis in an animal model of wet-type age-related macular degeneration. LbCpf1 targeting Vegfa or Hif1a effectively disrupted the expression of genes in ocular tissues, resulting in suppression of choroidal neovascularization. It was also notable that there were no significant off-target effects in vivo. [BMB Reports 2018; 51(7): 315-316].

CRISPR-LbCpf1 prevents choroidal neovascularization in a mouse model of age-related macular degeneration

LbCpf1, derived from Lachnospiraceae bacterium ND2006, is a CRISPR RNA-guided endonuclease and holds promise for therapeutic applications. Here we show that LbCpf1 can be used for therapeutic gene editing in a mouse model of age-related macular degeneration (AMD). The intravitreal delivery of LbCpf1, targeted to two angiogenesis-associated genes encoding vascular endothelial growth factor A (Vegfa) and hypoxia inducing factor 1a (Hif1a), using adeno-associated virus, led to efficient gene disruption with no apparent off-target effects in the retina and retinal pigment epithelium (RPE) cells. Importantly, LbCpf1 targeted to Vegfa or Hif1a in RPE cells reduced the area of laser-induced choroidal neovascularization as efficiently as aflibercept, an anti-VEGF drug currently used in the clinic, without inducing cone dysfunction. Unlike aflibercept, LbCpf1 targeted to Vegfa or Hif1a achieved a long-term therapeutic effect on CNV, potentially avoiding repetitive injections. Taken together, these results indicate that LbCpf1-mediated in vivo genome editing to ablate pathologic angiogenesis provides an effective strategy for the treatment of AMD and other neovascularization-associated diseases.

Anti-complement component 5 antibody targeting MG4 domain inhibits choroidal neovascularization

Age-related macular degeneration (AMD) is one of the main causes of visual impairment in adults. Visual deterioration is more prominent in neovascular AMD with choroidal neovascularization (CNV). Clinical and postmortem studies suggested that complement system activation might induce CNV. In this study, we demonstrated that an anti-mouse complement component 5 (C5) antibody targeting MG4 domain of β chain effectively inhibited CNV which was induced by laser photocoagulation in mice. The targeted epitope of this anti-C5 antibody was different from that of currently utilized anti-C5 antibody (eculizumab) in the MG7 domain in which a single nucleotide polymorphism (R885H/C) results in poor response to eculizumab. Even with targeting MG4 domain, this anti-C5 antibody reduced production of C5a, monocyte chemoattractant protein-1 and vascular endothelial growth factor to prevent infiltration of F4/80-positive cells into CNV lesions and formation of CNV. Furthermore, anti-C5 antibody targeting MG4 domain induced no definite toxicity in normal retina. These results demonstrated that anti-C5 antibody targeting MG4 domain inhibited CNV in neovascular AMD.

Gold Nanocrystals with Well-Defined Crystallographic {111} Facets Suppress Pathological Neovascularization

Vascular endothelial growth factor (VEGF) is a main factor in pathological neovascularization in various human diseases including age-related macular degeneration, cancer, and diabetic complications. Interestingly, gold nanospheres are known to bind to VEGF and to suppress VEGF-mediated angiogenesis. The anti-angiogenic effects are known to be governed by the size and surface charge of the nanoparticles. However, studies on the role of the shape in biological actions are limited. In this study, we investigate the anti-angiogenic properties of nanocrystals that have well-defined crystallographic {111} facets. Single-crystalline icosahedral and octahedral gold nanocrystals effectively scavenge VEGF just as nanospheres with similar diameter. In addition, they suppress the in vitro VEGF-induced activation of the VEGF receptor and the proliferation of endothelial cells. They also significantly inhibit in vivo VEGF-mediated retinal vascular permeability. These results thus suggest that gold nanocrystals with {111} facets can provide a useful platform for nanoparticle-based treatment of VEGF-driven pathological neovascularization beyond their current optical and catalytic applications.

Chronological Changes in Tip Cells during Sprouting Angiogenesis of Development of the Retinal Vasculature in Newborn Mice

PURPOSE

To investigate a sequential chronological change in tip cells during the development of the retinal vasculature in newborn mice.

MATERIALS AND METHODS

Newborn C57BL/6 mice were used for this study. To elucidate the patterns in the developing retinal vasculature, histology, and immunohistochemistry-antiplatelet endothelial cell adhesion molecule-1, anticollagen type IV, isolectin IB₄-were performed on sections of mouse retina on postnatal days (P)-4, -8, and -12. Staining patterns of isolectin IB₄-stained arterial and venous tip cells were compared in retinal wholemounts, in which the numbers and characteristics of tip cells were compared between arteries and veins on P-4, -6, and -8. In addition, vascular densities and branching patterns were compared between arterial and venous vascular forefront areas.

RESULTS

Tip cells in the superficial vascular plexus were observed until P-8. The number of tip cells was highest on P-6, decreasing dramatically from P-6 to P-8 (P-4, 165.2 ± 10.1, n = 17; P-6, 183.8 ± 19.4, n = 15; P8, 21.4 ± 6.4, n = 15) (p < 0.05, respectively, t-test). There was a greater number of tip cells in veins versus arteries on P-4 and P-6 (P-4, 91.0 ± 9.2 veins versus 74.2 ± 10.4 arteries; P-6, 104.0 ± 10.2 veins versus 79.8 ± 11.3 arteries) (p < 0.05, respectively). Arterial tip cells had thinner and longer sprouts compared with venous tip cells (basal thickness: 15.7 ± 8.7 veins versus 9.9 ± 3.5 μm arteries) (length, 20.3 ± 9.1 veins versus 37.1 ± 13.2 μm arteries on P-4) (p < 0.05, respectively). Vessel areas and densities of vascular branch points were significantly higher around veins compared to arteries (vessel areas: 58.9 ± 1.2% veins versus 40.8 ± 1.9% arteries; vascular branch points, 1371.9 ± 136.7/mm² veins versus 1046.7 ± 175.5/mm² arteries) (p < 0.05, respectively).

CONCLUSION

The number of tip cells increased to a greater extent in the superficial vascular plexus of veins versus arteries until P-6. Consequently, there are more vessel areas and vascular branch points near retinal veins versus arteries. Arterial tip cells are longer and thinner than the shorter and thicker venous tip cells.

L1 increases adhesion-mediated proliferation and chemoresistance of retinoblastoma

Retinoblastoma is the most common intraocular cancer in children, affecting 1/20,000 live births. Currently, children with retinoblastoma were treated with chemotherapy using drugs such as carboplatin, vincristine, and etoposide. Unfortunately, if conventional treatment fails, the affected eyes should be removed to prevent extension into adjacent tissues and metastasis. This study is to investigate the roles of L1 in adhesion-mediated proliferation and chemoresistance of retinoblastoma. L1 was differentially expressed in 30 retinoblastoma tissues and 2 retinoblastoma cell lines. Furthermore, the proportions of L1-positive cells in retinoblastoma tumors were negatively linked with the number of Flexner-Wintersteiner rosettes, a characteristic of differentiated retinoblastoma tumors, in each tumor sample. Following in vitro experiments using L1-deleted and -overexpressing cells showed that L1 increased adhesion-mediated proliferation of retinoblastoma cells via regulation of cell cycle-associated proteins with modulation of Akt, extracellular signal-regulated kinase, and p38 pathways. In addition, L1 increased resistance against carboplatin, vincristine, and esoposide through up-regulation of apoptosis- and multidrug resistance-related genes. In vivo tumor formation and chemoresistance were also positively linked with the levels of L1 in an orthotopic transplantation model in mice. In this manner, L1 increases adhesion-mediated proliferation and chemoresistance of retinoblastoma. Targeted therapy to L1 might be effective in the treatment of retinoblastoma tumors, especially which rapidly proliferate and demonstrate resistance to conventional chemotherapeutic drugs.

Microneedle-based minimally-invasive measurement of puncture resistance and fracture toughness of sclera

The sclera provides the structural support of the eye and protects the intraocular contents. Since it covers a large portion of the eye surface and has relatively high permeability for most drugs, the sclera has been used as a major pathway for drug administration. Recently, microneedle (MN) technology has shown the possibility of highly local and minimally-invasive drug delivery to the eye by MN insertion through the sclera or the suprachoroidal space. Although ocular MN needs to be inserted through the sclera, there has been no systematic study to understand the mechanical properties of the sclera, which are important to design ocular MNs. In this study, we investigated a MN-based method to measure the puncture resistance and fracture toughness of the sclera. To reflect the conditions of MN insertion into the sclera, force-displacement curves obtained from MN-insertion tests were used to estimate the puncture resistance and fracture toughness of sclera tissue. To understand the effect of the insertion conditions, dependency of the mechanical properties on insertion speeds, pre-strain of the sclera, and MN sizes were analyzed and discussed.

STATEMENT OF SIGNIFICANCE

Measurement of mechanical property of soft biological tissue is challenging due to variations between tissue samples or lack of well-defined measurement techniques. Although non-invasive measurement techniques such as nano/micro indentation were employed to locally measure the elastic modulus of soft biological materials, mechanical properties such as puncture resistance or fracture toughness, which requires "invasive" measurement and is important for the application of "microneedles or hypodermic needles", has not been well studied. In this work, we report minimally-invasive measurement of puncture resistance and fracture toughness of sclera using a double MN insertion method. Parametric studies showed that use of MN proved to be advantageous because of minimally-invasive insertion into tissue as well as higher sensitivity to sub-tissue architecture during the measurement.