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Propensity of Patient-Derived iPSCs for Retinal Differentiation: Implications for Autologous Cell Replacement

Tue, 2023-05-23 05:00

Stem Cells Transl Med. 2023 May 23:szad028. doi: 10.1093/stcltm/szad028. Online ahead of print.


Prior to use, newly generated induced pluripotent stem cells (iPSC) should be thoroughly validated. While excellent validation and release testing assays designed to evaluate potency, genetic integrity, and sterility exist, they do not have the ability to predict cell type-specific differentiation capacity. Selection of iPSC lines that have limited capacity to produce high-quality transplantable cells, places significant strain on valuable clinical manufacturing resources. The purpose of this study was to determine the degree and root cause of variability in retinal differentiation capacity between cGMP-derived patient iPSC lines. In turn, our goal was to develop a release testing assay that could be used to augment the widely used ScoreCard panel. IPSCs were generated from 15 patients (14-76 years old), differentiated into retinal organoids, and scored based on their retinal differentiation capacity. Despite significant differences in retinal differentiation propensity, RNA-sequencing revealed remarkable similarity between patient-derived iPSC lines prior to differentiation. At 7 days of differentiation, significant differences in gene expression could be detected. Ingenuity pathway analysis revealed perturbations in pathways associated with pluripotency and early cell fate commitment. For example, good and poor producers had noticeably different expressions of OCT4 and SOX2 effector genes. QPCR assays targeting genes identified via RNA sequencing were developed and validated in a masked fashion using iPSCs from 8 independent patients. A subset of 14 genes, which include the retinal cell fate markers RAX, LHX2, VSX2, and SIX6 (all elevated in the good producers), were found to be predictive of retinal differentiation propensity.

PMID:37221451 | DOI:10.1093/stcltm/szad028

Stress resilience-enhancing drugs preserve tissue structure and function in degenerating retina via phosphodiesterase inhibition

Mon, 2023-05-01 05:00

Proc Natl Acad Sci U S A. 2023 May 9;120(19):e2221045120. doi: 10.1073/pnas.2221045120. Epub 2023 May 1.


Chronic, progressive retinal diseases, such as age-related macular degeneration (AMD), diabetic retinopathy, and retinitis pigmentosa, arise from genetic and environmental perturbations of cellular and tissue homeostasis. These disruptions accumulate with repeated exposures to stress over time, leading to progressive visual impairment and, in many cases, legal blindness. Despite decades of research, therapeutic options for the millions of patients suffering from these disorders remain severely limited, especially for treating earlier stages of pathogenesis when the opportunity to preserve the retinal structure and visual function is greatest. To address this urgent, unmet medical need, we employed a systems pharmacology platform for therapeutic development. Through integrative single-cell transcriptomics, proteomics, and phosphoproteomics, we identified universal molecular mechanisms across distinct models of age-related and inherited retinal degenerations, characterized by impaired physiological resilience to stress. Here, we report that selective, targeted pharmacological inhibition of cyclic nucleotide phosphodiesterases (PDEs), which serve as critical regulatory nodes that modulate intracellular second messenger signaling pathways, stabilized the transcriptome, proteome, and phosphoproteome through downstream activation of protective mechanisms coupled with synergistic inhibition of degenerative processes. This therapeutic intervention enhanced resilience to acute and chronic forms of stress in the degenerating retina, thus preserving tissue structure and function across various models of age-related and inherited retinal disease. Taken together, these findings exemplify a systems pharmacology approach to drug discovery and development, revealing a new class of therapeutics with potential clinical utility in the treatment or prevention of the most common causes of blindness.

PMID:37126699 | DOI:10.1073/pnas.2221045120

The role of personal-use negative pressure wound therapy with enhanced functionality in achieving wound-related treatment goals: a small prospective study

Tue, 2023-03-14 05:00

Wounds. 2023 Mar;35(3):53-58.


BACKGROUND: NPWT is widely used to manage hard-to-heal wounds, and many different devices are available. Personal-use NPWT systems are becoming more popular, although current options have limited functionality.

PURPOSE: The primary objective was to determine acceptable progress of wounds towards a predefined goal of therapy for a variety of open wounds being treated with a novel NPWT personal-use system with enhanced functionality.

METHODS: In this prospective, nonrandomized, interventional study, patients were treated with a personal-use NPWT system over 4 weeks, initially in a wound care clinic setting, and were discharged home with the device. Clinician satisfaction with the device was also evaluated.

RESULTS: Ten patients were evaluated. Acceptable progress towards all predetermined goals was reached for all patients; a median reduction in wound volume of 84.6% and improved granulation was achieved within the 4-week treatment period. No device-related deficiencies were reported. In general, clinicians were satisfied with the device's ease of use and mobility.

CONCLUSION: Personal-use NPWT is easy to use, has positive effects on healing on a variety of wound types, and is well accepted by clinicians.


Automating iPSC generation to enable autologous photoreceptor cell replacement therapy

Wed, 2023-03-01 05:00

J Transl Med. 2023 Feb 28;21(1):161. doi: 10.1186/s12967-023-03966-2.


BACKGROUND: Inherited retinal degeneration is a leading cause of incurable vision loss in the developed world. While autologous iPSC mediated photoreceptor cell replacement is theoretically possible, the lack of commercially available technologies designed to enable high throughput parallel production of patient specific therapeutics has hindered clinical translation.

METHODS: In this study, we describe the use of the Cell X precision robotic cell culture platform to enable parallel production of clinical grade patient specific iPSCs. The Cell X is housed within an ISO Class 5 cGMP compliant closed aseptic isolator (Biospherix XVivo X2), where all procedures from fibroblast culture to iPSC generation, clonal expansion and retinal differentiation were performed.

RESULTS: Patient iPSCs generated using the Cell X platform were determined to be pluripotent via score card analysis and genetically stable via karyotyping. As determined via immunostaining and confocal microscopy, iPSCs generated using the Cell X platform gave rise to retinal organoids that were indistinguishable from organoids derived from manually generated iPSCs. In addition, at 120 days post-differentiation, single-cell RNA sequencing analysis revealed that cells generated using the Cell X platform were comparable to those generated under manual conditions in a separate laboratory.

CONCLUSION: We have successfully developed a robotic iPSC generation platform and standard operating procedures for production of high-quality photoreceptor precursor cells that are compatible with current good manufacturing practices. This system will enable clinical grade production of iPSCs for autologous retinal cell replacement.

PMID:36855199 | DOI:10.1186/s12967-023-03966-2

The degree of AAV-induced retinal inflammation varies based on serotype and route of delivery: intravitreal, subretinal or suprachoroidal

Thu, 2023-02-16 05:00

Hum Gene Ther. 2023 Feb 15. doi: 10.1089/hum.2022.222. Online ahead of print.


Adeno-associated virus (AAV) mediated gene therapy has great potential for treating a wide range of retinal degenerative diseases. However, some initial enthusiasm for gene therapy has been tempered by emerging evidence of AAV-associated inflammation, which in several instances has contributed to clinical trial discontinuation. Currently, there is a paucity of data describing the variable immune responses to different AAV serotypes, and similarly, little is known regarding how these responses differ depending on route of ocular delivery, including in animal models of disease. In this study, we characterize the severity and retinal distribution of AAV-associated inflammation in rats triggered by delivery of 5 different AAV vectors (AAV1, AAV2, AAV6, AAV8, AAV9), each of which contained eGFP driven under control of the constitutively active CMV promoter. We further compare the inflammation across 3 different potential routes (intravitreal, subretinal, suprachoroidal) of ocular delivery. Compared to buffer-injected controls for each route of delivery, AAV2 and AAV6 induced the most inflammation across all routes of delivery of the vectors tested, with AAV6 inducing the highest levels of inflammation when delivered suprachoroidally. AAV1-induced inflammation was highest when delivered suprachoroidally, whereas minimal inflammation was seen with intravitreal delivery. AAV8 and AAV9 induced minimal inflammation across all routes of delivery. Importantly, the degree of inflammation was not correlated with vector-mediated transduction and expression of eGFP. These data emphasize the importance of considering ocular inflammation when selecting AAV serotypes and ocular delivery routes for the development of gene therapy strategies.

PMID:36793189 | DOI:10.1089/hum.2022.222

Transcriptomic and chromatin accessibility analysis of the human macular and peripheral retinal pigment epithelium at the single cell level

Sun, 2023-02-12 05:00

Am J Pathol. 2023 Feb 10:S0002-9440(23)00045-7. doi: 10.1016/j.ajpath.2023.01.012. Online ahead of print.


Human retinal diseases are frequently characterized by pathology that is restricted to specific cell types and to specific regions of the eye. Several disease entities either selectively affect or spare the macula, the retinal region at the center of the posterior pole. Photoreceptor cells of the macula are responsible for high acuity vision and require metabolic support from non-neuronal cell types. Macular diseases often involve an epithelial cell layer known as the retinal pigment epithelium (RPE) that has several essential metabolic support functions for the overlying photoreceptors. In the current study, we probed how the RPE confers region-specific disease susceptibility by examining heterogeneity within human donor RPE. We profiled RPE nuclei from the macular and peripheral retina using joint single-cell RNA and ATAC sequencing. We found that the expression of several genes varies between macular and peripheral RPE. We further found region-specific ATAC peaks implying regulatory elements used exclusively by macular or peripheral RPE. Across anatomical regions, we identify subpopulations of RPE that appear to have differential expression levels of visual cycle genes. Finally, we examined loci connected to age related macular degeneration to better understand RPE-specific disease phenotypes. Together, these data show how gene expression regulation in the human RPE varies by region and subpopulation and provide a resource for better understanding the molecular basis of macular disease.

PMID:36775060 | DOI:10.1016/j.ajpath.2023.01.012

Retinal Pigment Epithelium-Secreted VEGF-A Induces Alpha-2-Macroglobulin Expression in Endothelial Cells

Fri, 2022-10-14 05:00

Cells. 2022 Sep 24;11(19):2975. doi: 10.3390/cells11192975.


Alpha-2-macroglobulin (A2M) is a protease inhibitor that regulates extracellular matrix (ECM) stability and turnover. Here, we show that A2M is expressed by endothelial cells (ECs) from human eye choroid. We demonstrate that retinal pigment epithelium (RPE)-conditioned medium induces A2M expression specifically in ECs. Experiments using chemical inhibitors, blocking antibodies, and recombinant proteins revealed a key role of VEGF-A in RPE-mediated A2M induction in ECs. Furthermore, incubation of ECs with RPE-conditioned medium reduces matrix metalloproteinase-2 gelatinase activity of culture supernatants, which is partially restored after A2M knockdown in ECs. We propose that dysfunctional RPE or choroidal blood vessels, as observed in retinal diseases such as age-related macular degeneration, may disrupt the crosstalk mechanism we describe here leading to alterations in the homeostasis of choroidal ECM, Bruch's membrane and visual function.

PMID:36230937 | PMC:PMC9564307 | DOI:10.3390/cells11192975

Characterization of a novel Pde6b-deficient rat model of retinal degeneration and treatment with adeno-associated virus (AAV) gene therapy

Thu, 2022-09-29 05:00

Gene Ther. 2022 Sep 29. doi: 10.1038/s41434-022-00365-y. Online ahead of print.


In humans, mutations in the beta subunit of cGMP-phosphodiesterase type 6 (PDE6B) cause autosomal recessive retinitis pigmentosa (RP), which typically has an aggressive clinical course of early-onset severe vision loss due to rapid photoreceptor degeneration. In this study, we describe the generation of a novel Pde6b-deficient rat model using CRISPR-Cas9 genome editing. We characterize the model at multiple time points using clinical imaging modalities as well as histology with immunohistochemistry to show rapid photoreceptor degeneration compared to wild-type and heterozygous animals. We describe the manufacture of two different adeno-associated viral (AAV) vectors (AAV2/1, AAV2/5) under current Good Manufacturing Practices (cGMP) and demonstrate their ability to drive human PDE6B expression in vivo. We further demonstrate the ability of AAV-mediated subretinal gene therapy to delay photoreceptor loss in Pde6b-deficient rats compared to untreated controls. However, severe progressive photoreceptor loss was noted even in treated eyes, likely due to the aggressive nature of the disease. These data provide useful preclinical data to guide the development of potential human gene therapy for PDE6B-associated RP. In addition, the rapid photoreceptor degeneration of the Pde6b-deficient rat with intact inner retina may provide a useful model for the study of cell replacement strategies.

PMID:36175490 | DOI:10.1038/s41434-022-00365-y

Vascular Findings in the Choriocapillaris in a Case of Radiation Retinopathy Secondary to Choroidal Melanoma

Mon, 2022-09-26 05:00

Case Rep Ophthalmol. 2022 Aug 15;13(2):589-598. doi: 10.1159/000525568. eCollection 2022 May-Aug.


The effects of radiation retinopathy on the retinal vasculature have been well established; however, the literature describing the pathologic changes in the choriocapillaris is relatively lacking. In this report, we describe the histologic findings of a donor eye with a choroidal melanoma with special attention to the choriocapillaris. Clinical and histological findings, including immunohistochemistry and transmission electron microscopy, are described for the retina and choroid of a donor eye affected by radiation retinopathy secondary to treatment of choroidal melanoma. Cells within the tumor exhibited an epithelioid structure and balloon melanosomes. Notable infiltration of macrophages with elongated morphology was also observed. Atrophy of photoreceptors, retinal pigmented epithelium, and choriocapillaris was observed on the inferior edge of the lesion and extending past the tumor. The choriocapillaris endothelium showed more severe dropout at the periphery of the lesion where loss of fenestration, thickened cytosol, and degenerated pericytes were observed. Morphologic analysis revealed choriocapillaris loss with pronounced degeneration of choroidal pericytes. Understanding the differences in sensitivity to radiation injury between different cell types and different patients will provide better insight into radiation retinopathy.

PMID:36160486 | PMC:PMC9459633 | DOI:10.1159/000525568

Systems genomics in age-related macular degeneration

Thu, 2022-09-15 05:00

Exp Eye Res. 2022 Dec;225:109248. doi: 10.1016/j.exer.2022.109248. Epub 2022 Sep 13.


Genomic studies in age-related macular degeneration (AMD) have identified genetic variants that account for the majority of AMD risk. An important next step is to understand the functional consequences and downstream effects of the identified AMD-associated genetic variants. Instrumental for this next step are 'omics' technologies, which enable high-throughput characterization and quantification of biological molecules, and subsequent integration of genomics with these omics datasets, a field referred to as systems genomics. Single cell sequencing studies of the retina and choroid demonstrated that the majority of candidate AMD genes identified through genomic studies are expressed in non-neuronal cells, such as the retinal pigment epithelium (RPE), glia, myeloid and choroidal cells, highlighting that many different retinal and choroidal cell types contribute to the pathogenesis of AMD. Expression quantitative trait locus (eQTL) studies in retinal tissue have identified putative causal genes by demonstrating a genetic overlap between gene regulation and AMD risk. Linking genetic data to complement measurements in the systemic circulation has aided in understanding the effect of AMD-associated genetic variants in the complement system, and supports that protein QTL (pQTL) studies in plasma or serum samples may aid in understanding the effect of genetic variants and pinpointing causal genes in AMD. A recent epigenomic study fine-mapped AMD causal variants by determing regulatory regions in RPE cells differentiated from induced pluripotent stem cells (iPSC-RPE). Another approach that is being employed to pinpoint causal AMD genes is to produce synthetic DNA assemblons representing risk and protective haplotypes, which are then delivered to cellular or animal model systems. Pinpointing causal genes and understanding disease mechanisms is crucial for the next step towards clinical translation. Clinical trials targeting proteins encoded by the AMD-associated genomic loci C3, CFB, CFI, CFH, and ARMS2/HTRA1 are currently ongoing, and a phase III clinical trial for C3 inhibition recently showed a modest reduction of lesion growth in geographic atrophy. The EYERISK consortium recently developed a genetic test for AMD that allows genotyping of common and rare variants in AMD-associated genes. Polygenic risk scores (PRS) were applied to quantify AMD genetic risk, and may aid in predicting AMD progression. In conclusion, genomic studies represent a turning point in our exploration of AMD. The results of those studies now serve as a driving force for several clinical trials. Expanding to omics and systems genomics will further decipher function and causality from the associations that have been reported, and will enable the development of therapies that will lessen the burden of AMD.

PMID:36108770 | DOI:10.1016/j.exer.2022.109248

The Essential Role of the Choriocapillaris in Vision: Novel Insights from Imaging and Molecular Biology

Thu, 2022-09-15 05:00

Annu Rev Vis Sci. 2022 Sep 15;8:33-52. doi: 10.1146/annurev-vision-100820-085958.


The choriocapillaris, a dense capillary network located at the posterior pole of the eye, is essential for supporting normal vision, supplying nutrients, and removing waste products from photoreceptor cells and the retinal pigment epithelium. The anatomical location, heterogeneity, and homeostatic interactions with surrounding cell types make the choroid complex to study both in vivo and in vitro. Recent advances in single-cell RNA sequencing, in vivo imaging, and in vitro cell modeling are vastly improving our knowledge of the choroid and its role in normal health and in age-related macular degeneration (AMD). Histologically, loss of endothelial cells (ECs) of the choriocapillaris occurs early in AMD concomitant with elevated formation of the membrane attack complex of complement. Advanced imaging has allowed us to visualize early choroidal blood flow changes in AMD in living patients, supporting histological findings of loss of choroidal ECs. Single-cell RNA sequencing is being used to characterize choroidal cell types transcriptionally and discover their altered patterns of gene expression in aging and disease. Advances in induced pluripotent stem cell protocols and 3D cultures will allow us to closely mimic the in vivo microenvironment of the choroid in vitro to better understand the mechanism leading to choriocapillaris loss in AMD.

PMID:36108103 | PMC:PMC9668353 | DOI:10.1146/annurev-vision-100820-085958

Biocompatibility of Human Induced Pluripotent Stem Cell-Derived Retinal Progenitor Cell Grafts in Immunocompromised Rats

Mon, 2022-06-27 05:00

Cell Transplant. 2022 Jan-Dec;31:9636897221104451. doi: 10.1177/09636897221104451.


Loss of photoreceptor cells is a primary feature of inherited retinal degenerative disorders including age-related macular degeneration and retinitis pigmentosa. To restore vision in affected patients, photoreceptor cell replacement will be required. The ideal donor cells for this application are induced pluripotent stem cells (iPSCs) because they can be derived from and transplanted into the same patient obviating the need for long-term immunosuppression. A major limitation for retinal cell replacement therapy is donor cell loss associated with simple methods of cell delivery such as subretinal injections of bolus cell suspensions. Transplantation with supportive biomaterials can help maintain cellular integrity, increase cell survival, and encourage proper cellular alignment and improve integration with the host retina. Using a pig model of retinal degeneration, we recently demonstrated that polycaprolactone (PCL) scaffolds fabricated with two photon lithography have excellent local and systemic tolerability. In this study, we describe rapid photopolymerization-mediated production of PCL-based bioabsorbable scaffolds, a technique for loading iPSC-derived retinal progenitor cells onto the scaffold, methods of surgical transplantation in an immunocompromised rat model and tolerability of the subretinal grafts at 1, 3, and 6 months of follow-up (n = 150). We observed no local or systemic toxicity, nor did we observe any tumor formation despite extensive clinical evaluation, clinical chemistry, hematology, gross tissue examination and detailed histopathology. Demonstrating the local and systemic compatibility of biodegradable scaffolds carrying human iPSC-derived retinal progenitor cells is an important step toward clinical safety trials of this approach in humans.

PMID:35758274 | PMC:PMC9247396 | DOI:10.1177/09636897221104451

Inflammatory adipose activates a nutritional immunity pathway leading to retinal dysfunction

Wed, 2022-06-15 05:00

Cell Rep. 2022 Jun 14;39(11):110942. doi: 10.1016/j.celrep.2022.110942.


Age-related macular degeneration (AMD), the leading cause of irreversible blindness among Americans over 50, is characterized by dysfunction and death of retinal pigment epithelial (RPE) cells. The RPE accumulates iron in AMD, and iron overload triggers RPE cell death in vitro and in vivo. However, the mechanism of RPE iron accumulation in AMD is unknown. We show that high-fat-diet-induced obesity, a risk factor for AMD, drives systemic and local inflammatory circuits upregulating interleukin-1β (IL-1β). IL-1β upregulates RPE iron importers and downregulates iron exporters, causing iron accumulation, oxidative stress, and dysfunction. We term this maladaptive, chronic activation of a nutritional immunity pathway the cellular iron sequestration response (CISR). RNA sequencing (RNA-seq) analysis of choroid and retina from human donors revealed that hallmarks of this pathway are present in AMD microglia and macrophages. Together, these data suggest that inflamed adipose tissue, through the CISR, can lead to RPE pathology in AMD.

PMID:35705048 | PMC:PMC9248858 | DOI:10.1016/j.celrep.2022.110942

New approaches to the treatment of Age-Related Macular Degeneration (AMD)

Thu, 2022-06-02 05:00

Exp Eye Res. 2022 Aug;221:109134. doi: 10.1016/j.exer.2022.109134. Epub 2022 May 30.


PMID:35654115 | DOI:10.1016/j.exer.2022.109134

Age-Related Macular Degeneration Masquerade: A Review of Pentosan Polysulfate Maculopathy and Implications for Clinical Practice

Mon, 2022-05-09 05:00

Asia Pac J Ophthalmol (Phila). 2022 Mar-Apr 01;11(2):100-110. doi: 10.1097/APO.0000000000000504.


Pentosan polysulfate (PPS) sodium (Elmiron) is the only Food and Drug Administration (FDA)-approved oral medication to treat interstitial cystitis, also known as bladder pain syndrome. A symptomatic pigmentary maculopathy associated with PPS was reported in 2018. Since then, recognition of this unique drug toxicity has increased rapidly. This potentially sight-threatening side effect prompted the FDA in June 2020 to update the label for PPS to warn about "retinal pigmentary changes." A challenging feature of pentosan maculopathy is its ability to mimic many other retinal conditions, including inherited retinal dystrophies such as pattern dystrophy, mitochondrially inherited diabetes and deafness, and Stargardt disease, and age-related macular degeneration. In this review, we discuss the history of PPS maculopathy and its implications for thousands of at-risk interstitial cystitis patients. We use published literature and an illustrative case from our institution to highlight the importance of diagnosing PPS maculopathy. We also compare PPS maculopathy to age-related macular degeneration, explain why differentiating between the 2 is clinically important, and highlight avenues for further research. Finally, we highlight the paucity of data on patients of color and why this lack of understanding may impact patient care.

PMID:35533330 | PMC:PMC9096915 | DOI:10.1097/APO.0000000000000504

Choroidal endothelial and macrophage gene expression in atrophic and neovascular macular degeneration

Sat, 2022-02-19 05:00

Hum Mol Genet. 2022 Jul 21;31(14):2406-2423. doi: 10.1093/hmg/ddac043.


The human choroid is a heterogeneous, highly vascular connective tissue that dysfunctions in age-related macular degeneration (AMD). In this study, we performed single-cell RNA sequencing on 21 human choroids, 11 of which were derived from donors with early atrophic or neovascular AMD. Using this large donor cohort, we identified new gene expression signatures and immunohistochemically characterized discrete populations of resident macrophages, monocytes/inflammatory macrophages and dendritic cells. These three immune populations demonstrated unique expression patterns for AMD genetic risk factors, with dendritic cells possessing the highest expression of the neovascular AMD-associated MMP9 gene. Additionally, we performed trajectory analysis to model transcriptomic changes across the choroidal vasculature, and we identified expression signatures for endothelial cells from choroidal arterioles and venules. Finally, we performed differential expression analysis between control, early atrophic AMD, and neovascular AMD samples, and we observed that early atrophic AMD samples had high expression of SPARCL1, a gene that has been shown to increase in response to endothelial damage. Likewise, neovascular endothelial cells harbored gene expression changes consistent with endothelial cell damage and demonstrated increased expression of the sialomucins CD34 and ENCM, which were also observed at the protein level within neovascular membranes. Overall, this study characterizes the molecular features of new populations of choroidal endothelial cells and mononuclear phagocytes in a large cohort of AMD and control human donors.

PMID:35181781 | PMC:PMC9307320 | DOI:10.1093/hmg/ddac043

Local factor H production by human choroidal endothelial cells mitigates complement deposition: implications for macular degeneration

Mon, 2022-01-17 05:00

J Pathol. 2022 May;257(1):29-38. doi: 10.1002/path.5867. Epub 2022 Feb 17.


Activation of the alternative complement pathway is an initiating event in the pathology of age-related macular degeneration (AMD). Unchecked complement activation leads to the formation of a pro-lytic pore, the membrane attack complex (MAC). MAC deposition is observed on the choriocapillaris of AMD patients and likely causes lysis of choroidal endothelial cells (CECs). Complement factor H (FH, encoded by the gene CFH) is an inhibitor of complement. Both loss of function of FH and reduced choroidal levels of FH have been reported in AMD. It is plausible that reduced local FH availability promotes MAC deposition on CECs. FH is produced primarily in the liver; however, cells including the retinal pigment epithelium can produce FH locally. We hypothesized that CECs produce FH locally to protect against MAC deposition. We aimed to investigate the effect of reduced FH levels in the choroid to determine whether increasing local FH could protect CECs from MAC deposition. We demonstrated that siRNA knockdown of FH (CFH) in human immortalized CECs results in increased MAC deposition. We generated AMD iPSC-derived CECs and found that overexpression of FH protects against MAC deposition. These results suggest that local CEC-produced FH protects against MAC deposition, and that increasing local FH protein may be beneficial in limiting MAC deposition in AMD. © 2022 The Pathological Society of Great Britain and Ireland.

PMID:35038170 | PMC:PMC9007903 | DOI:10.1002/path.5867

Correlation of features on OCT with visual acuity and Gass lesion type in Best vitelliform macular dystrophy

Fri, 2022-01-07 05:00

BMJ Open Ophthalmol. 2021 Dec 7;6(1):e000860. doi: 10.1136/bmjophth-2021-000860. eCollection 2021.


OBJECTIVE: To correlate structural features seen on optical coherence tomography (OCT) with best-corrected visual acuity (BCVA) and Gass lesion type in patients with Best vitelliform macular dystrophy (BVMD).

METHODS AND ANALYSIS: This is a retrospective case series of consecutive patients with molecularly confirmed BEST1-associated BVMD. OCT scans were reviewed for lesion status and presence of subretinal pillar, focal choroidal excavation (FCE), intraretinal fluid or atrophy. Available OCT angiography images were used to evaluate for the presence of choroidal neovascularisation (CNV). These features were then correlated with BCVA and Gass lesion type.

RESULTS: 95 eyes from 48 patients (mean age 38.9 years, range 4-87) were included. The presence of a pillar (24.2%), FCE (20.0%) and atrophy (7.4%) were associated with poor BCVA (p<0.05). Gass lesion type 1 eyes were correlated with good BCVA (LogMAR <0.4) whereas type 5 eyes had poor BCVA (LogMAR >0.4). Among 65 eyes with longitudinal data (mean follow-up 5.1 years), 7 eyes (10.8%) reverted from higher to lower Gass lesion type; of these, 4 eyes (57.1%) had CNV responsive to intravitreal anti-vascular endothelial growth factor treatment.

CONCLUSION: OCT-based structural features are readily identifiable in patients with BVMD and have prognostic importance due to their correlation with BCVA.

PMID:34993349 | PMC:PMC8655537 | DOI:10.1136/bmjophth-2021-000860

Chimeric Helper-Dependent Adenoviruses Transduce Retinal Ganglion Cells and Müller Cells in Human Retinal Explants

Fri, 2021-10-01 05:00

J Ocul Pharmacol Ther. 2021 Dec;37(10):575-579. doi: 10.1089/jop.2021.0057. Epub 2021 Oct 1.


Purpose: Despite numerous recent advances in retinal gene therapy using adeno-associated viruses (AAVs) as delivery vectors, there remains a crucial need to identify viral vectors with the ability to transduce specific retinal cell types and that have a larger carrying capacity than AAV. In this study, we evaluate the retinal tropism of 2 chimeric helper-dependent adenoviruses (HDAds), helper-dependent adenovirus serotype 5 (HDAd5)/3 and HDAd5/35, both ex vivo using human retinal explants and in vivo using rats. Methods: We transduced cultured human retinal explants with HDAd5/3 and HDAd5/35 carrying an eGFP vector and evaluated tropism and transduction efficiency using immunohistochemistry. To assess in vivo transduction efficiency, subretinal injections were performed in wild-type Sprague-Dawley rats. For both explants and subretinal injections, we delivered 10 μL (1 × 106 vector genomes/mL) and assessed tropism at 7- and 14-days post-transduction, respectively. Results: HDAd5/3 and HDAd5/35 both transduced human retinal ganglion cells (RGCs) and Müller cells, but not photoreceptors, in human retinal explants. However, subretinal injections in albino rats resulted in transduction of the retinal pigmented epithelium only, highlighting species-specific differences in retinal tropism and the value of a human explant model when testing vectors for eventual human gene therapy. Conclusions: Chimeric HDAds are promising candidates for the delivery of large genes, multiple genes, or neuroprotective factors to Müller cells and RGCs. These vectors may have utility for targeted therapy of neurodegenerative diseases primarily involving retinal ganglion or Müller cell types, such as glaucoma or macular telangiectasia type 2.

PMID:34597181 | PMC:PMC8713574 | DOI:10.1089/jop.2021.0057

Sensitive quantification of m.3243A&gt;G mutational proportion in non-retinal tissues and its relationship with visual symptoms

Thu, 2021-09-30 05:00

Hum Mol Genet. 2022 Mar 3;31(5):775-782. doi: 10.1093/hmg/ddab289.


The m.3243A>G mutation in the mitochondrial genome commonly causes retinal degeneration in patients with maternally inherited diabetes and deafness and mitochondrial encephalopathy, lactic acidosis and stroke-like episodes. Like other mitochondrial mutations, m.3243A>G is inherited from the mother with a variable proportion of wild type and mutant mitochondrial genomes in different cells. The mechanism by which the m.3243A>G variant in each tissue relates to the manifestation of disease phenotype is not fully understood. Using a digital PCR assay, we found that the % m.3243G in skin derived dermal fibroblasts was positively correlated with that of blood from the same individual. The % m.3243G detected in fibroblast cultures remained constant over multiple passages and was negatively correlated with mtDNA copy number. Although the % m.3243G present in blood was not correlated with severity of vision loss, as quantified by Goldmann visual field, a significant negative correlation between % m.3243G and the age of onset of visual symptoms was detected. Altogether, these results indicate that precise measurement of % m.3243G in clinically accessible tissues such as skin and blood may yield information relevant to the management of retinal m.3243A>G-associated disease.

PMID:34590675 | PMC:PMC8895728 | DOI:10.1093/hmg/ddab289