Editorial: Somatic Cell Gene Editing for Treating Diseases

Editorial on the Special Issue with the Research Topic: Somatic Cell Gene Editing for Treating Diseasesinfo:eu-repo/semantics/publishedVersio

CRISPR‐based gene therapy for wet age‐related macular degeneration in mouse model

Abstract Wet age‐related macular degeneration (AMD) is a common cause of vision loss in the elderly. It is characterised by choroidal neovascularisation (CNV), caused by overexpression of vascular endothelial growth factor (VEGF), resulting in abnormal vessel proliferation. Current clinical management predominantly relies on anti‐VEGF agents, which require frequent and costly injections. Clustered regularly interspaced short palindromic repeats (CRISPR) technology has emerged as a promising strategy for permanently suppressing angiogenesis by targeting the VEGF‐related pathway. Increased research suggests that disrupting this pathway holds potential for preventing CNV progression. This review provides an overview of the aetiology, classification and pathophysiology of wet AMD, followed by a concise summary of current gene editing research using the CRISPR/Cas system via viral vector delivery strategies to target ocular pro‐angiogenic factors, including Hif‐1α, VEGF and VEGFR. The importance of timely targeting of VEGFA is emphasised and the challenges associated with gene editing therapies are also highlighted

Effects of cigarette smoke on fertilization and embryo development in vivo

OBJECTIVE:To determine the effects of smoking on eggs and subsequent embryo development by maternal exposure to cigarette smoke. DESIGN: Mice were exposed to cigarette smoke or cigarette smoke condensate (CSC) for 4 weeks and then examined for development and telomere function of embryos in vitro after fertilization. In addition, the effects of continuous smoke on embryo development and telomere length were determined by treating mice for 4 weeks, followed by continuous exposure to cigarette smoke or CSC after fertilization. SETTING: Laboratory study. ANIMAL(S): CD1 mice. INTERVENTION(S): Mice were exposed to cigarette smoke or CSC. MAIN OUTCOME MEASURE(S): The percentage (rate) of blastocyst development, quality of embryos assessed by total cell number, apoptosis, Oct4 expression (a molecular marker of embryonic stem cells), telomere length and loss, and chromosomal instability were compared between smoke- and CSC- treated mice and sham-treated mice. RESULT(S): Mice exposed to cigarette smoke or CSC for 4 weeks exhibited increased egg fragmentation or delayed fertilization, thus reducing development to blastocysts in vitro. Fragmented eggs showed increased reactive oxygen species. Mice exposed to smoke or CSC showed increased apoptosis and altered expression of Oct4 in developed embryos. The effects of smoke or CSC on embryo development showed a dose-dependent relationship to exposure time. Exposure to smoke or CSC beginning 4 weeks before fertilization altered expression of Oct4 and increased apoptosis in blastocysts. Notably, the rate of abnormal embryos significantly increased in the smoke and CSC groups. Smoke and CSC shortened telomeres in embryos, but their telomere shortening was not enough to induce major chromosome abnormalities in mice, which have unusually long telomeres. CONCLUSION(S): Together, the whole animal exposure model shows that cigarette smoke induces oxidative stress, telomere shortening, and apoptosis, and compromises embryo development in vivo

Telomere susceptibility to cigarette smoke-induced oxidative damage and chromosomal instability of mouse embryos in vitro

Cigarette smoke is associated with high risk of lung, cardiovascular, and degenerative diseases, reduced fertility, and possibly the health of newborns. Cigarette smoke contains many components and exerts its genotoxicity in part by generating reactive oxidative stress. Telomeres consist of repeated ‘G’ rich sequences and associated proteins located at the chromosomal ends that maintain chromosomal integrity. We tested the hypothesis that telomere shortening and dysfunction are implicated in smoke associated oxidative damage and chromosomal instability using early mouse embryos in vitro and short-telomere mouse model. Mouse embryos exposed to smoke components, cigarette smoke condensate (CSC) at the concentration of 0.02 mg/ ml continuously or 0.1 mg/ml for 20 h, or cadmium at 5-100 μM, exhibited increased oxidative stress and telomere shortening and loss, associated with chromosomal instability, apoptosis, and compromised embryo cleavage and development. Remarkably, reduction of oxidative stress by an antioxidant N-acetyl-L-cysteine (NAC) greatly reduced these toxicities. Notably, cadmium led to more severe oxidative damage and telomere dysfunction, which could be more effectively rescued by antioxidant treatment, than did CSC. Moreover, short telomeres predisposed embryos to smoke component-induced oxidative damage. These data further extend our understanding of mechanisms underlying smoke-induced oxidative damage to include telomere dysfunction and chromosomal instability

The long non-coding RNA Snhg3 is essential for mouse embryonic stem cell self-renewal and pluripotency

Background: Small nucleolar RNA host gene 3 (Snhg3) is a long non-coding RNA (lncRNA) that was shown to participate in the tumorigenesis of certain cancers. However, little is known about its role in embryonic stem cells (ESCs). Methods: Here, we investigated the role of Snhg3 in mouse ESCs (mESCs) through both loss-of-function (knockdown) and gain-of-function (overexpression) approaches. Alkaline phosphatase staining, secondary colony formation, propidium iodide staining, western blotting, and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were used to access self-renewal capacity, whereas immunofluorescence, qRT-PCR, and embryoid body formation were performed to examine pluripotency. In addition, the effect of Snhg3 on mouse embryonic development was determined based on the morphological changes, blastocyst rate, and altered pluripotency marker (Nanog, Oct4) expression. Moreover, the relationship between Snhg3 and key pluripotency factors was evaluated by chromatin immunoprecipitation qPCR, qRT-PCR, subcellular fractionation, and RNA immunoprecipitation. Finally, RNA pull-down and mass spectrometry were applied to explore the potential interacting proteins of Snhg3 in mESCs. Results: We demonstrated that Snhg3 is essential for self-renewal and pluripotency maintenance in mESCs. In addition, Snhg3 knockdown disrupted mouse early embryo development. Mechanistically, Snhg3 formed a positive feedback network with Nanog and Oct4, and 126 Snhg3-interacting proteins were identified in mESCs. Conclusions: Snhg3 is essential for mESC self-renewal and pluripotency, as well as mouse early embryo development.Medicine, Faculty ofNon UBCDermatology and Skin Science, Department ofReviewedFacult

Vitamin C plus hydrogel facilitates bone marrow stromal cell-mediated endometrium regeneration in rats

Abstract Background Intrauterine adhesion (IUA) is a common uterine cavity disease which can be caused by mechanical damage that may eventually lead to infertility and pregnancy abnormalities. Since the effect of therapeutic drugs appears disappointing, cell therapy has emerged as an alternative choice for endometrium regeneration. The aim of this study is to investigate whether the combination of hydrogel Pluronic F-127 (PF-127), Vitamin C (Vc), and a bone marrow stromal cell (BMSC) mixture could be a feasible strategy to improve the endometrial regeneration in a mechanical damage model of IUA in rats. Methods Firstly, PF-127 cytotoxicity and the effect of Vc was tested in vitro using the Annexin V/propidium iodide (PI) apoptosis test, cell count kit (CCK) growth test, and enzyme-linked immunosorbent assay (ELISA). For the establishment of the rat IUA model, a 2-mm transverse incision in the uterus was prepared at the upper end, and 1.5- to 2.0-cm endometrial damage was scraped. Rats were randomly assigned to five groups to investigate the combined strategy on IUA uterine regeneration: a sham group, an IUA control group, an IUA BMSC encapsulated in PF-127 plus Vc group, an IUA BMSC plus Vc group, and an IUA PF-127 plus Vc group. A cell mixture was injected into the uterine horn while making the IUA model. Eight weeks after cell transplantation, the rats were sacrificed and the uterine was dissected for analysis. Endometrial thickness, gland number, fibrosis area, and the expression of marker proteins for endometrial membrane were examined by hematoxylin and eosin staining, Masson’s staining, and immunohistochemistry. Results Vc promoted the survival and health of PF-127-encapsulated BMSCs in vitro. When this combination was transplanted in vivo, the endometrium showed better restoration as the endometrium membrane became thicker and had more glands and less fibrosis areas. The expression of cytokeratin, von Willebrand Factor (vWF), was also restored. The proinflammatory cytokine interleukin-1β (IL-1β) was significantly lower compared with the control group. Conclusions Vc alleviates the cytotoxic effect of PF-127 and promotes cell survival and growth in rat BMSC encapsulation. Thus, a cell therapy strategy containing biomaterial scaffold, BMSCs and the modulatory factor Vc promotes the restoration of damaged IUA endometrium

Nme2Cas9‐mediated therapeutic editing in inhibiting angiogenesis after wet age‐related macular degeneration onset

Abstract Background Age‐related macular degeneration (AMD), particularly wet AMD characterised by choroidal neovascularization (CNV), is a leading cause of vision loss in the elderly. The hypoxia‐inducible factor‐1α (HIF‐1α)/vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGFR2) pathway contributes to CNV pathogenesis. Previous gene editing research indicated that disrupting these genes in retinal pigment epithelial cells could have a preventive effect on CNV progression. However, no studies have yet been conducted using gene editing to disrupt VEGF signalling after CNV induction for therapeutic validation, which is critical to the clinical application of wet AMD gene editing therapies. Method Here, we employed the single‐adeno‐associated virus‐mediated Nme2Cas9 to disrupt key molecules in VEGF signalling, Hif1α, Vegfa and Vegfr2 after inducing CNV and estimated their therapeutic effects. Results We found that Nme2Cas9 made efficient editing in target genes up to 71.8% post 11 days in vivo. And only Nme2Cas9‐Vegfa treatment during the early stage of CNV development reduced the CNV lesion area by 49.5%, compared to the negative control, while Nme2Cas9‐Hif1α or Nme2Cas9‐Vegfr2 treatment did not show therapeutic effect. Besides, no off‐target effects were observed in Nme2Cas9‐mediated gene editing in vivo. Conclusions This study provides proof‐of‐concept possibility of employing Nme2Cas9 for potential anti‐angiogenesis therapy in wet AMD

Parental genetic material and oxygen concentration affect hatch dynamics of mouse embryo in vitro

Abstract Background Hatching is crucial for mammalian embryo implantation, since difficulties during this process can lead to implantation failure, ectopic pregnancy and consequent infertility. Despite years of intensive researches, how internal and external factors affecting embryo hatch are still largely unclear. Methods The effects of parental genetic material and oxygen concentration on hatch process were examined. Fertilized and parthenogenetic mouse preimplantation embryos were cultured in vitro under 5 and 20% oxygen for 120 h. Zona pellucida drilling by Peizo micromanipulation were performed to resemble the breach by sperm penetration. Results Firstly, parthenogenetic embryos had similarly high blastocyst developmental efficiency as fertilized embryos, but significantly higher hatch ratio than fertilized embryos in both O2 concentrations. 5% O2 reduced the hatch rate of fertilized embryos from 58.2 to 23.8%, but increased that of parthenogenetic embryos from 81.2 to 90.8% significantly. Analogously, 5% O2 decreased the ratio of Oct4-positive cells in fertilized blastocysts, whereas increased that in parthenogenetic blastocysts. Additionally, 5% O2 increased the total embryonic cell number in both fertilized and parthegenetic embryos, when compared to 20% O2, and the total cell number of fertilized embryos was also higher than that of parthegenetic embryos, despite O2 concentration. Real-time PCR revealed that the expression of key genes involving in MAPK pathway and superoxide dismutase family might contribute to preimplantation development and consequent blastocyst hatch in vitro. Finally, we showed that fertilized and parthenogenetic embryos have diverse hatch dynamics in vitro, although the zona pellucida integrity is not the main reason for their mechanistic differences. Conclusion Both parental genetic material and O2 concentration, as the representative of intrinsic and extrinsic factors respectively, have significant impacts on mouse preimplantation development and subsequent hatch dynamics, probably by regulating the gene expression involving in MAPK pathway and superoxide dismutase family to control embryonic cell proliferation and allocation of ICM cells

Specific Tandem 3'UTR Patterns and Gene Expression Profiles in Mouse Thy1⁺ Germline Stem Cells

<div><p>A recently developed strategy of sequencing alternative polyadenylation (APA) sites (SAPAS) with second-generation sequencing technology can be used to explore complete genome-wide patterns of tandem APA sites and global gene expression profiles. spermatogonial stem cells (SSCs) maintain long-term reproductive abilities in male mammals. The detailed mechanisms by which SSCs self-renew and generate mature spermatozoa are not clear. To understand the specific alternative polyadenylation pattern and global gene expression profile of male germline stem cells (GSCs, mainly referred to SSCs here), we isolated and purified mouse Thy1⁺ cells from testis by magnetic-activated cell sorting (MACS) and then used the SAPAS method for analysis, using pluripotent embryonic stem cells (ESCs) and differentiated mouse embryonic fibroblast cells (MEFs) as controls. As a result, we obtained 99,944 poly(A) sites, approximately 40% of which were newly detected in our experiments. These poly(A) sites originated from three mouse cell types and covered 17,499 genes, including 831 long non-coding RNA (lncRNA) genes. We observed that GSCs tend to have shorter 3'UTR lengths while MEFs tend towards longer 3'UTR lengths. We also identified 1337 genes that were highly expressed in GSCs, and these genes were highly consistent with the functional characteristics of GSCs. Our detailed bioinformatics analysis identified APA site-switching events at 3'UTRs and many new specifically expressed genes in GSCs, which we experimentally confirmed. Furthermore, qRT-PCR was performed to validate several events of the 334 genes with distal-to-proximal poly(A) switch in GSCs. Consistently APA reporter assay confirmed the total 3'UTR shortening in GSCs compared to MEFs. We also analyzed the cis elements around the proximal poly(A) site preferentially used in GSCs and found C-rich elements may contribute to this regulation. Overall, our results identified the expression level and polyadenylation site profiles and these data provide new insights into the processes potentially involved in the GSC life cycle and spermatogenesis.</p></div