Project description:Ensuring genome safety during gene editing is crucial for clinical translation of the high-efficient CRISPR-Cas9 toolbox. Therefore, the undesired events including chromosomal translocations, vector integrations, and large deletions arising during therapeutic gene editing remain to be adequately addressed or tackled in vivo. Here, we apply CRISPR-Cas9TX in comparison to CRISPR-Cas9 to target Vegfa for the treatment of age-related macular degeneration (AMD) disease in a mouse model. AAV delivery of both CRISPR-Cas9 and CRISPR-Cas9TX can efficiently inhibit laser-induced neovascularization. Importantly, Cas9TX almost eliminates chromosomal translocations that occur at a frequency of approximately 1% in Cas9-edited mouse retinal cells. Strikingly, the widely observed AAV integration at the target Vegfa site is also greatly dropped from nearly 50% of edited events to the background level during Cas9TX editing. Our findings reveal that chromosomal structural variations routinely occur during in vivo genome editing and highlight Cas9TX as a superior form of Cas9 for in vivo gene disruption.
Project description:CLINICAL QUESTION:Is there any new knowledge about the pathogenesis and treatment of age-related macular degeneration (AMD)? RESULTS:We now understand better the biochemical and pathological pathways involved in the genesis of AMD. Treatment of exudative AMD is based on intravitreal injection of new antivascular endothelial growth factor drugs for which there does not yet exist a unique recognized strategy of administration. No therapies are actually available for atrophic AMD, despite some experimental new pharmacological approaches. IMPLEMENTATION:strategy of administration, safety of intravitreal injection.
Project description:While the development of anti-vascular endothelial growth factor (anti-VEGF) as a therapy for neovascular age-related macular degeneration (AMD) was a great success, the pathologic processes underlying dry AMD that eventually leads to photoreceptor dysfunction, death, and vision loss remain elusive to date, with a lack of effective therapies and increasing prevalence of the disease. There is an overwhelming need to improve the classification system of AMD, to increase our understanding of cell death mechanisms involved in both neovascular and non-neovascular AMD, and to develop better biomarkers and clinical endpoints to eventually be able to identify better therapeutic targets-especially early in the disease process. There is no doubt that it is a matter of time before progress will be made and better therapies will be developed for non-neovascular AMD.
Project description:Pathological neovascularization is a key component of the neovascular form (also known as the wet form) of age-related macular degeneration (AMD) and proliferative diabetic retinopathy. Several preclinical studies have shown that antiangiogenesis strategies are effective for treating neovascular AMD in animal models. Vascular endothelial growth factor (VEGF) is one of the main inducers of ocular neovascularization, and several clinical trials have shown the benefits of neutralizing VEGF in patients with neovascular AMD or diabetic macular edema. In this review, we summarize several preclinical and early-stage clinical trials with intraocular gene therapies, which have the potential to reduce or eliminate the repeated intravitreal injections that are currently required for the treatment of neovascular AMD.
Project description:Gene expression is the first step in ascribing function between an associated gene and disease. Understanding how variation in a gene influences expression, particularly in tissues affected by the disease, may help elucidate what influences the phenotypic outcome of that disease. Previous studies of the genetics of age-related macular degeneration (AMD) have identified several risk factors, but have not yet bridged the gap between gene association and identifying a specific mechanism or function that is involved in the pathogenesis of AMD. Advances in genomic technologies, such as RNA sequencing (RNA-seq), single cell RNA-seq, bilsulfite sequencing, and/or whole genome methylation, will be powerful tools for identifying genes/pathways that are differentially expressed in those with AMD versus those without AMD. These technologies should advance the field of AMD research so that appropriate preventive and therapeutic targets can be developed.
Project description:Age-related macular degeneration (AMD) is the leading cause of irreversible visual loss in the developed countries and is caused by both environmental and genetic factors. A recent study (Tuo et al., PNAS) reported an association between AMD and a single nucleotide polymorphism (SNP) (rs3793784) in the ERCC6 (NM_000124) gene. The risk allele also increased ERCC6 expression. ERCC6 is involved in DNA repair and mutations in ERCC6 cause Cockayne syndrome (CS). Amongst others, photosensitivity and pigmentary retinopathy are hallmarks of CS.Separate and combined data from three large AMD case-control studies and a prospective population-based study (The Rotterdam Study) were used to analyse the genetic association between ERCC6 and AMD (2682 AMD cases and 3152 controls). We also measured ERCC6 mRNA levels in retinal pigment epithelium (RPE) cells of healthy and early AMD affected human donor eyes. Rs3793784 conferred a small increase in risk for late AMD in the Dutch population (The Rotterdam and AMRO-NL study), but this was not replicated in two non-European studies (AREDS, Columbia University). In addition, the AMRO-NL study revealed no significant association for 9 other variants spanning ERCC6. Finally, we determined that ERCC6 expression in the human RPE did not depend on rs3793784 genotype, but, interestingly, on AMD status: Early AMD-affected donor eyes had a 50% lower ERCC6 expression than healthy donor eyes (P?=?0.018).Our meta-analysis of four Caucasian cohorts does not replicate the reported association between SNPs in ERCC6 and AMD. Nevertheless, our findings on ERCC6 expression in the RPE suggest that ERCC6 may be functionally involved in AMD. Combining our data with those of the literature, we hypothesize that the AMD-related reduced transcriptional activity of ERCC6 may be caused by diverse, small and heterogeneous genetic and/or environmental determinants.
Project description:Age-related macular degeneration (AMD) is a complex disease that has two phases: a degenerative phase often referred to as nonneovascular AMD (non-NVAMD) or dry AMD and a phase dominated by growth of new blood vessels in the subretinal space, referred to as NVAMD or wet AMD. Advances in the understanding of the molecular pathogenesis of NVAMD have led to new drug therapies that have provided major benefits to patients. However, those treatments require frequent intraocular injections that in many patients must be continued indefinitely to maintain visual benefits. Gene transfer to augment expression of endogenous antiangiogenic proteins is an alternative approach that has the potential to provide long-term stability in patients with NVAMD. Studies in animal models that mimic aspects of NVAMD have identified several possible transgenes, and a clinical trial in patients with advanced NVAMD has suggested that the approach may be feasible. Many important questions remain, but the rationale and preliminary data are compelling. The results of two ongoing clinical trials may answer several of the questions and help direct future research.
Project description:AAV2-sFLT01 is a vector that expresses a modified soluble Flt1 receptor designed to neutralize the proangiogenic activities of vascular endothelial growth factor (VEGF) for treatment of age-related macular degeneration (AMD) via an intravitreal injection. Owing to minimal data available for the intravitreal route of administration for adeno-associated virus (AAV), we initiated a 12-month safety study of AAV2-sFLT01 administered intravitreally at doses of 2.4 × 10(9) vector genomes (vg) and 2.4 × 10(10) vg to cynomolgus monkeys. Expression of sFlt01 protein peaked at ~1-month postadministration and remained relatively constant for the remainder of the study. Electroretinograms, fluorescein angiograms, and tonometry were assessed every 3 months, with no test article-related findings observed in any group. Indirect ophthalmoscopy and slit lamp exams performed monthly revealed a mild to moderate but self-resolving vitreal inflammation in the high-dose group only, which follow-up studies suggest was directed against the AAV2 capsid. Histological evaluation revealed no structural changes in any part of the eye and occasional inflammatory cells in the trabecular meshwork, vitreous and retina in the high-dose group. Biodistribution analysis in rats and monkeys found only trace amounts of vector outside the injected eye. In summary, these studies found AAV2-sFLT01 to be well-tolerated, localized, and capable of long-term expression.
Project description:This SuperSeries is composed of the following subset Series: GSE28002: Gene expression of the whole mouse eye GSE28032: Epigenetic Regulation of IL17RC in Age-related Macular Degeneration (MeDIP-chip) Refer to individual Series
Project description:Age-related macular degeneration (AMD) leads to irreversible visual loss, therefore, early intervention is desirable, but due to its multifactorial nature, diagnosis of early disease might be challenging. Identification of early markers for disease development and progression is key for disease diagnosis. Suitable biomarkers can potentially provide opportunities for clinical intervention at a stage of the disease when irreversible changes are yet to take place. One of the most metabolically active tissues in the human body is the retina, making the use of hypothesis-free techniques, like metabolomics, to measure molecular changes in AMD appealing. Indeed, there is increasing evidence that metabolic dysfunction has an important role in the development and progression of AMD. Therefore, metabolomics appears to be an appropriate platform to investigate disease-associated biomarkers. In this review, we explored what is known about metabolic changes in the retina, in conjunction with the emerging literature in AMD metabolomics research. Methods for metabolic biomarker identification in the eye have also been discussed, including the use of tears, vitreous, and aqueous humor, as well as imaging methods, like fluorescence lifetime imaging, that could be translated into a clinical diagnostic tool with molecular level resolution.