De-Kuang Hwang

Detection of aqueous VEGF concentrations before and after intravitreal injection of anti-VEGF antibody using low-volume sampling paper-based ELISA

Intraocular vascular endothelial growth factor (VEGF) levels play an important role in the pathogenesis of blindness-related diseases, such as age-related macular degeneration (AMD). Here, we aimed to develop a paper-based enzyme-linked immunosorbent assay (P-ELISA) to analyze the suppression of aqueous VEGF concentrations following intravitreal injection (IVI) of anti-VEGF antibody (bevacizumab or ranibizumab). A total of 25 eyes with wet AMD, one with myopic neovascularization, and one with polypoidal choroidal vasculopathy were enrolled in this study. The limit of detection using P-ELISA was 0.03u2009pg/mL. Forty-six consecutive samples of aqueous humor were acquired. From all samples, 66.67% (10/15) achieved complete VEGF suppression (below the detection limit) within 5 weeks of receiving IVI of anti-VEGF antibody. Only 13.33% of samples (2/15) achieved complete VEGF suppression 5 weeks after receiving treatment. In some patients, elevated VEGF was still detected 5 weeks after receipt of anti-VEGF antibody, and all samples (10/10) were found to have elevated VEGF levels 49 days after treatment. Thus, we suggest that monthly IVI of anti-VEGF antibody may be required to ensure durable VEGF inhibition. Ultrasensitive P-ELISA can detect elevated VEGF at an earlier time point and may facilitate decision-making regarding appropriate treatment strategies.

Laminin modification subretinal bio-scaffold remodels retinal pigment epithelium-driven microenvironment in vitro and in vivo.

Advanced age-related macular degeneration (AMD) may lead to geographic atrophy or fibrovascular scar at macular, dysfunctional retinal microenvironment, and cause profound visual loss. Recent clinical trials have implied the potential application of pluripotent cell-differentiated retinal pigment epithelial cells (dRPEs) and membranous scaffolds implantation in repairing the degenerated retina in AMD. However, the efficacy of implanted membrane in immobilization and supporting the viability and functions of dRPEs, as well as maintaining the retinal microenvironment is still unclear. Herein we generated a biomimetic scaffold mimicking subretinal Bruchs basement from plasma modified polydimethylsiloxane (PDMS) sheet with laminin coating (PDMS-PmL), and investigated its potential functions to provide a subretinal environment for dRPE-monolayer grown on it. Firstly, compared to non-modified PDMS, PDMS-PmL enhanced the attachment, proliferation, polarization, and maturation of dRPEs. Second, PDMS-PmL increased the polarized tight junction, PEDF secretion, melanosome pigment deposit, and phagocytotic-ability of dRPEs. Third, PDMS-PmL was able to carry a dRPEs/photoreceptor-precursors multilayer retina tissue. Finally, the in vivo subretinal implantation of PDMS-PmL in porcine eyes showed well-biocompatibility up to 2-year follow-up. Notably, multifocal ERGs at 2-year follow-up revealed well preservation of macular function in PDMS-PmL, but not PDMS, transplanted porcine eyes. Trophic PEDF secretion of macular retina in PDMS-PmL group was also maintained to preserve retinal microenvironment in PDMS-PmL eyes at 2 year. Taken together, these data indicated that PDMS-PmL is able to sustain the physiological morphology and functions of polarized RPE monolayer, suggesting its potential of rescuing macular degeneration in vivo.

Generation of patient-specific induced pluripotent stem cells from Leber's hereditary optic neuropathy

Lebers hereditary optic neuropathy (LHON) is a maternally inherited mitochondrial disease caused by homoplasmic point mutations in complex I subunit genes of mitochondrial DNA. In this report, we generated an induced pluripotent stem cell (iPSCs) line, TVGH-iPSC-010-09, from the peripheral blood mononuclear cells of a female patient with Lebers hereditary optic neuropathy (LHON) by using the Sendai-virus delivery system. The resulting iPSCs retained the disease-causing mitochondrial DNA mutation, expressed pluripotent markers and could differentiate into the three germ layers. We believe LHON patient-specific iPSCs provide a powerful in vitro model for evaluating the pathological phenotypes of the disease.

Bioactivity and gene expression profiles of hiPSC-generated retinal ganglion cells in MT-ND4 mutated Leber's hereditary optic neuropathy

Abstract Leber’s hereditary optic neuropathy (LHON) is the maternally inherited mitochondrial disease caused by homoplasmic mutations in mitochondrial electron transport chain Complex I subunit genes. The mechanism of its incomplete penetrance is still largely unclear. In this study, we created the patient‐specific human induced pluripotent stem cells (hiPSCs) from MT‐ND4 mutated LHON‐affected patient, asymptomatic mutation carrier and healthy control, and differentiated them into retinal ganglion cells (RGCs). We found the defective neurite outgrowth in affected RGCs, but not in the carrier RGCs which had significant expression of SNCG gene. We observed enhanced mitochondrial biogenesis in affected and carrier derived RGCs. Surprisingly, we observed increased NADH dehydrogenase enzymatic activity of Complex I in hiPSC‐derived RGCs of asymptomatic carrier, but not of the affected patient. LHON mutation substantially decreased basal respiration in both affected and unaffected carrier hiPSCs, and had the same effect on spare respiratory capacity, which ensures normal function of mitochondria in conditions of increased energy demand or environmental stress. The expression of antioxidant enzyme catalase was decreased in affected and carrier patient hiPSC‐derived RGCs as compared to the healthy control, which might indicate to higher oxidative stress‐enriched environment in the LHON‐specific RGCs. Microarray profiling demonstrated enhanced expression of cell cycle machinery and downregulation of neuronal specific genes. HighlightshiPSCs were obtained from LHON‐mutation affected and carrier individuals.LHON‐specific hiPSCs were differentiated to RGCs to create in vitro disease model.LHON‐affected RGCs have defective neuritogenesis.LHON‐specific RGCs have increased compensatory mitochondrial biogenesis.LHON‐affected mitochondria have decreased spare respiratory capacity.

Expression profiling of cell-intrinsic regulators in the process of differentiation of human iPSCs into retinal lineages

BackgroundDifferentiation of human induced pluripotent stem cells (hiPSCs) into retinal lineages offers great potential for medical application. Therefore, it is of crucial importance to know the key intrinsic regulators of differentiation and the specific biomarker signatures of cell lineages.MethodsIn this study, we used microarrays to analyze transcriptomes of terminally differentiated retinal ganglion cell (RGC) and retinal pigment epithelium (RPE) lineages, as well as intermediate retinal progenitor cells of optic vesicles (OVs) derived from hiPSCs. In our analysis, we specifically focused on the classes of transcripts that encode intrinsic regulators of gene expression: the transcription factors (TFs) and epigenetic chromatin state regulators. We applied two criteria for the selection of potentially important regulators and markers: firstly, the magnitude of fold-change of upregulation; secondly, the contrasted pattern of differential expression between OV, RGC and RPE lineages.ResultsWe found that among the most highly overexpressed TF-encoding genes in the OV/RGC lineage were three members of the Collier/Olfactory-1/Early B-cell family: EBF1, EBF2 and EBF3. Knockdown of EBF1 led to significant impairment of differentiation of hiPSCs into RGCs. EBF1 was shown to act upstream of ISL1 and BRN3A, the well-characterized regulators of RGC lineage specification. TF-encoding genes DLX1, DLX2 and INSM1 were the most highly overexpressed genes in the OVs, indicating their important role in the early stages of retinal differentiation. Along with MITF, the two paralogs, BHLHE41 and BHLHE40, were the most robust TF markers of RPE cells. The markedly contrasted expression of ACTL6B, encoding the component of chromatin remodeling complex SWI/SNF, discriminated hiPSC-derived OV/RGC and RPE lineages.ConclusionsWe identified novel, potentially important intrinsic regulators of RGC and RPE cell lineage specification in the process of differentiation from hiPSCs. We demonstrated the crucial role played by EBF1 in differentiation of RGCs. We identified intrinsic regulator biomarker signatures of these two retinal cell types that can be applied with high confidence to confirm the cell lineage identities.

Generation of induced pluripotent stem cells from a patient with X-linked juvenile retinoschisis

X-linked juvenile retinoschisis (XLRS) is a hereditary retinal dystrophy manifested as splitting of anatomical layers of retina. In this report, we generated a patient-specific induced pluripotent stem cell (iPSC) line, TVGH-iPSC-013-05, from the peripheral blood mononuclear cells of a male patient with XLRS by using the Sendai-virus delivery system. We believe that XLRS patient-specific iPSCs provide a powerful in vitro model for evaluating the pathological phenotypes of the disease.

Generation of induced pluripotent stem cells from a patient with Best Dystrophy carrying 11q12.3 (BEST1 (VMD2)) mutation

Best disease (BD), also termed Best vitelliform macular dystrophy (BVMD), is a juvenile-onset form of macular degeneration and central visual loss. In this report, we generated an induced pluripotent stem cell (iPSC) line, TVGH-iPSC-012-04, from the peripheral blood mononuclear cells of a female patient with BD by using the Sendai virus delivery system. The resulting iPSCs retained the disease-causing DNA mutation, expressed pluripotent markers and could differentiate into three germ layers. We believe that BD patient-specific iPSCs provide a powerful in vitro model for evaluating the pathological phenotypes of the disease.

Acoustic waves improves retroviral transduction in human retinal stem cells

Backgrounds: The plasticity of retinal stem cells (RSCs), a type of cells that can differentiate into neuron cells and photoreceptor cells, endows them with potential therapeutic properties that can be applied to regenerative medicine. Gene modification of these stem cells before trans‐differentiation and transplantation enhances their survival and increases their therapeutic function. The different ways to effectively deliver gene into RSCs are still discussed. This study aimed to use the acoustic waves to improve the efficacy of gene delivery for RSCs. Methods: RSCs were obtained from non‐fetal human ocular pigmented ciliary margin tissues. The enhanced green fluorescent protein‐encoded murine stem cell retroviruses (MSCV) were prepared and used to infect RSCs. Glass chambers containing RSCs, retroviruses, and various concentrations of polybrene (0, 0.8, 2, 4 and 8 &mgr;g/mL) were exposed under 20 or 25 Vp‐p ultrasonic standing wave fields (USWF) for 5 min. The percentage of green fluorescent protein positive cells in each sample was calculated and compared to test the efficacy of gene transduction. Results: Our results showed that the efficiency of gene transduction by MSCV infection was enhanced following the concentration of polybrene and the energy of USWF. The percentage of green fluorescent protein positive cells was significantly higher in chambers that contained 8 &mgr;g/mL of polybrene and was exposed to 20Vp‐p of USWF for 5 min. In addition, the percentage increased in chambers contained 2, 4 and 8 &mgr;g/mL of polybrene when they were exposed to 25Vp‐p of USWF. Comparing to those did not treated with ultrasound, the efficiency of retroviral transduction to RSCs increased 4‐fold after exposed to USWF for 5 min. Conclusion: We demonstrated the ability of ultrasound standing waves to improve retroviral transduction into RSCs. We believe that this may be applied to the experimental designs of future studies and may have possible therapeutic uses.

Noninfectious uveitis in the Asia–Pacific region

Uveitis is a sight-threatening disease. Up to 35% of patients may have impaired vision. Inflammation of the uvea tissue has more than 60 etiologies. Previous reports have shown that 20–40% of uveitis cases were noninfectious. Some of them may be associated with systemic rheumatological and autoimmune diseases but some may affect the eyes only. The epidemiology and clinical situations of some specific uveitis entities vary worldwide because they are influenced by genetic, ethnic, environmental, and socioeconomic factors. The Asia–Pacific region comprises more than 30 countries. Epidemiology and patterns of uveitis vary greatly in this region. However, some uveitis entities, such as Behcet’s disease, sarcoidosis, and Vogt–Koyanagi–Harada disease, are more common in this region. Many studies on the epidemiology, risk factors, and immune pathogenesis of this disease have been conducted. In this article, we review the epidemiology of noninfectious uveitis and special situations of these three uveitis entities in the Asia–Pacific region.摘要葡萄膜炎是一种影响视力的疾病。高达35%的患者可能有视力障碍。葡萄膜炎有60多种病因。过去的报告显示20%-40%的葡萄膜炎是非传染性的。其中一部分可能与系统性风湿病和自身免疫病有关, 但一部分只影响眼部。因为受到遗传、种族、环境和社会经济因素的影响, 一些葡萄膜炎的流行病学和临床发病情况在世界各地不同。亚太地区有30多个国家。该地区葡萄膜炎的流行病学和类型差异很大。然而, 一部分葡萄膜炎, 如贝塞氏病、结节病和小柳原田病, 在该地区更为常见。许多作者对该病的流行病学、危险因素和免疫发病机制进行了大量研究。本文综述了非传染性葡萄膜炎的流行病学和亚太地区这三种葡萄膜炎的发病特点。

Elevation of serum oxidative stress in patients with retina vein occlusions

Retina vein occlusion (RVO) is a visual‐threatening retinal disease that causes irreversible impaired quality of life. The contribution of oxidative stress behind clinical course of RVO was rarely investigated. The study aimed to measure the serum oxidative biomarker in patients with RVO to investigate further physical response.