The recent approval of the first gene editing therapy for sickle cell disease and transfusion-dependent beta-thalassemia by the U.S. Food and Drug Administration (FDA) demonstrates the immense potential of CRISPR (clustered regularly interspaced short palindromic repeats) technologies to treat patients with genetic disorders that were previously considered incurable. While significant advancements have been made with ex vivo gene editing approaches, the development of in vivo CRISPR/Cas gene editing therapies has not progressed as rapidly due to significant challenges in achieving highly efficient and specific in vivo delivery. Adeno-associated viral (AAV) vectors have shown great promise in clinical trials as vehicles for delivering therapeutic transgenes and other cargos but currently face multiple limitations for effective delivery of gene editing machineries. This review elucidates these challenges and highlights the latest engineering strategies aimed at improving the efficiency, specificity, and safety profiles of AAV-packaged CRISPR/Cas systems (AAV-CRISPR) to enhance their clinical utility.

Cadmium (Cd) is a toxic metal, which in some production areas reaches levels above allowed limits in cereals. Thus, reducing its concentration in cereals is crucial for mitigating health risks and complying with food safety regulations. This review evaluates strategies to reduce Cd accumulation in cereal grains by mitigating soil Cd contamination and its bioavailability to plants. It covers methods for Cd estimation in soil and explores biological, chemical, and genetic approaches to limit Cd uptake by crops. The effectiveness of these strategies depends on genetic factors, soil properties, and crop type. Key approaches include traditional breeding, genome editing, digital and predictive soil mapping, and silicon (Si) and selenium (Se) supplementation. Traditional breeding, enhanced by modern genetic tools, enables the development of high-yielding, low-Cd cultivars but is time-consuming. Genome editing, particularly CRISPR-Cas9, offers precise gene modifications to reduce Cd uptake but faces regulatory constraints. Digital and predictive soil mapping provide high-resolution maps for targeted interventions but require extensive calibration. Silicon supplementation is a promising approach, as it competes with Cd for uptake sites, and limits Cd translocation to edible plant parts. Additionally, Si enhances plant tolerance to abiotic stresses, making it a multifunctional solution. Selenium supplementation can also reduce Cd accumulation while offering health benefits. However, the effectiveness of both Si and Se vary with dosage and crop type. An integrated approach combining these strategies is essential for effective Cd reduction in cereals. Continued research, technological advancements, and supportive policies are crucial for ensuring safe and sustainable cereal production.

CRISPR-Cas9 is a useful tool for inserting precise genetic alterations through homology-directed repair (HDR), although current methods largely rely on provision of an exogenous repair template. Here, we tested the possibility of interchanging heterozygous single nucleotide variants (SNVs) using mutation-specific guide RNA, and the cell's own wild-type allele rather than an exogenous template. Using high-fidelity Cas9 to perform allele-specific CRISPR across multiple human leukemia cell lines as well as in primary hematopoietic cells from patients with leukemia, we find high levels of reversion to wild-type in the absence of exogenous template. Moreover, we demonstrate that bulk treatment to revert a truncating mutation in ASXL1 using CRISPR-mediated interallelic gene conversion (IGC) is sufficient to prolong survival in a human cell line-derived xenograft model (median survival 33 days vs 27.5 days; p = 0.0040). These results indicate that IGC is a useful laboratory tool which can be applied to numerous types of leukemia and can meaningfully alter cellular phenotypes at scale. Because our method targets single-base mutations, rather than larger variants targeted by IGC in prior studies, it greatly expands the pool of genetic lesions which could potentially be targeted by IGC. This technique may reduce cost and complexity for experiments modeling phenotypic consequences of SNVs. The principles of SNV-specific IGC demonstrated in this proof-of-concept study could be applied to investigate the phenotypic effects of targeted clonal reduction of leukemogenic SNV mutations.

The red fluorescent proteins (RFPs) and far-red fluorescent proteins (far-RFPs) that are encoded genetically can emit fluorescence within the spectral ranges of 580-680 nm when exposed to the light of appropriate wavelengths. Unlike many RFPs derived from coral species, numerous far-RFPs are optimized synthetic constructs engineered from different orange or red-emitting progenitors. Various categories have been established for the available RFPs and far-red fluorescent proteins based on their photo-chemical profile, fluorescence mechanism, and switching kinetics. Fluorescent probes (FPs) derived from these classes are extensively utilized for labelling and visualizing in vivo and in vitro specimens. Traditional optical microscopy methods generate diffraction-limited, indistinct images owing to the restricted resolution capability of light ranging from 200 to 300 nm. Since 2005, super-resolution microscopy has been a topic of great interest due to its ability to achieve imaging at spatial resolutions of less than 100 nm. The 2014 Nobel Prize in Chemistry was awarded to Eric Betzig, Stefan Hell, and William E. Moerner for their contributions to demonstrating the effectiveness of genetically encodable fluorescent proteins in visualizing biological systems through super-resolution fluorescence microscopy. This review provides a concise overview of RFPs and far-RFPs, including the involvement of surrounding residues in chromophore intactness, stability, autocatalytic maturation and switching kinetics. All the chemical pathways proposed for photoactivation, photoconversion and photoswitching mechanisms are concisely reviewed. Subsequently, a comprehensive summary was provided regarding the various types of super-resolution techniques that are commonly employed, elucidating their underlying principles of operation, as well as the potential future applications of RFPs/far-RFPs in the field of biological imaging.

Emerging genome editing and synthetic biology toolboxes can accurately program mammalian cells behavior from the inside-out. Such engineered living units can be perceived as key building blocks for bioengineering mammalian cell-dense materials, with promising features to be used as living therapeutics for tissue engineering or disease modeling applications. Aiming to reach full control over the code that governs cell behavior, inside-out engineering approaches have potential to fully unlock user-defined living materials encoded with tailored cellular functionalities and spatial arrangements. Dwelling on this, herein, we discuss the most recent advances and opportunities unlocked by genetic engineering strategies, and on their use for the assembly of next-generation cell-rich or cell-based materials, with an unprecedent control over cellular arrangements and customizable therapeutic capabilities. We envision that the continuous synergy between inside-out and outside-in cell engineering approaches will potentiate the future development of increasingly sophisticated cell assemblies that may operate with augmented biofunctionalities.

CGBE (C-to-G base editor) systems, pivotal components within the base editing arsenal, enable the precise conversion of cytosines to guanines. However, conventional cytidine deaminases possess non-specific single-stranded DNA binding properties, leading to off-target effects and safety concerns. The Cas-embedding strategy, which involves embedding functional proteins like deaminases within the Cas9 enzyme's architecture, emerges as a method to mitigate these off-target effects. Our study pioneers the application of the Cas-embedding strategy to CGBE systems, engineering a suite of novel CGBE editors, CE-CGBE. The CE-CGBE that incorporated eA3A, RBMX and Udgx excelled in editing efficiency, editing purity, and indel formation was named HF-CGBE. HF-CGBE showed no significant difference in off-target effects compared to the negative control group for both DNA and RNA. In summary, the novel HF-CGBE editors we propose expand the base editing toolbox and provide therapeutic approaches for related pathogenic mutations.

Gene editing has emerged as a promising therapeutic option for treating genetic diseases. However, a central challenge in the field is the safe and efficient delivery of these large editing tools, especially in vivo. Lipid nanoparticles (LNPs) are attractive nonviral vectors due to their low immunogenicity and high delivery efficiency. To maximize editing efficiency, LNPs should efficiently protect gene editing components against multiple biological barriers and release them into the cytoplasm of target cells. In this review, the widely used CRISPR gene editing systems are first overviewed. Then, each component of LNPs, as well as their effects on delivery, are systematically discussed. Following this, the current LNP engineering strategies to achieve non-liver targeting are summarized. Finally, preclinical and clinical applications of LNPs for in vivo genome editing are highlighted, and perspectives for the future development of LNPs are provided.

Trinucleotide repeat (TNR) diseases are neurological disorders caused by expanded genomic TNRs that become unstable in a length-dependent manner. The CAG•CTG sequence is found in approximately one-third of pathogenic TNR loci, including the HTT gene that causes Huntington's disease. Friedreich's ataxia, the most prevalent hereditary ataxia, results from GAA repeat expansion at the FXN gene. Here we used cytosine and adenine base editing to reduce the repetitiveness of TNRs in patient cells and in mice. Base editors introduced G•C>A•T and A•T>G•C interruptions at CAG and GAA repeats, mimicking stable, nonpathogenic alleles that naturally occur in people. AAV9 delivery of optimized base editors in Htt.Q111 Huntington's disease and YG8s Friedreich's ataxia mice resulted in efficient editing in transduced tissues, and significantly reduced repeat expansion in the central nervous system. These findings demonstrate that introducing interruptions in pathogenic TNRs can mitigate a key neurological feature of TNR diseases in vivo.

Genome editing technologies have emerged as the keystone of biotechnological research, enabling precise gene modification. The field has evolved rapidly through revolutionary advancements, transitioning from early explorations to the breakthrough of the CRISPR-Cas system. The emergence of the CRISPR-Cas system represents a huge leap in genome editing, prompting the development of advanced tools such as base and prime editors, thereby enhancing precise genomic engineering capabilities. The rapid integration of AI across disciplines is now driving another transformative phase in genome editing, streamlining workflows and enhancing precision. The application prospects of genome editing technology are extensive, particularly in plant breeding, where it has already presented unparalleled opportunities for improving plant traits. Here, we review early genome editing technologies, including meganucleases, ZFNs, TALENs, and CRISPR-Cas systems. We also provide a detailed introduction to next-generation editing tools-such as base editors and prime editors-and their latest applications in plants. At the same time, we summarize and prospect the cutting-edge developments and future trends of genome editing technologies in combination with the rapidly rising AI technology, including optimizing editing systems, predicting the efficiency of editing sites and designing editing strategies. We are convinced that as these technologies progress and their utilization expands, they will provide pioneering solutions to global challenges, ushering in an era of health, prosperity, and sustainability.

Cardiovascular diseases are the leading cause of death globally, with cardiac arrhythmias contributing substantially to this burden. Gene therapy, which directly targets the underlying disease pathobiology, offers an appealing treatment strategy for cardiac arrhythmias owing to its potential as a one-time, curative solution. Over the past two decades, substantial efforts have been made to develop new gene therapy approaches that overcome the limitations of conventional treatments. In this Review, we describe the rationale for gene therapy to treat cardiac arrhythmias; discuss advantages and disadvantages of gene silencing, gene replacement, gene suppression-and-replacement and gene editing technologies; summarize vector modalities and delivery approaches used in the field; present examples of gene therapy strategies used for atrial and ventricular arrhythmias; and highlight the current challenges and limitations in the gene therapy field.

Genome-editing technologies have enabled the clinical development of allogeneic cellular therapies, yet the optimal gene-editing modality for multiplex editing of therapeutic T cell product manufacturing remains elusive. In this study, we conducted a comprehensive comparison of CRISPR/Cas9 nuclease and adenine base editor (ABE) technologies in generating allogeneic chimeric antigen receptor (CAR) T cells, utilizing extensive in vitro and in vivo analyses. Both methods achieved high editing efficiencies across four target genes, critical for mitigating graft-versus-host disease and allograft rejection: TRAC or CD3E, B2M, CIITA, and PVR. Notably, ABE demonstrated higher manufacturing yields and distinct off-target profiles compared to Cas9, with translocations observed exclusively in Cas9-edited products. Functionally, ABE-edited CAR T cells exhibited superior in vitro effector functions under continuous antigen stimulation, including enhanced proliferative capacity and increased surface CAR expression. Transcriptomic analysis revealed that ABE editing resulted in reduced activation of p53 and DNA damage response pathways at baseline, along with sustained activation of metabolic pathways during antigen stress. Consistently, Assay for Transposase-Accessible Chromatin using sequencing data indicated that Cas9-edited, but not ABE-edited, CAR T cells showed enrichment of chromatin accessibility peaks associated with double-strand break repair and DNA damage response pathways. In a preclinical leukemia model, ABE-edited CAR T cells demonstrated improved tumor control and extended overall survival compared to their Cas9-edited counterparts. Collectively, these findings position ABE as superior to Cas9 nucleases for multiplex gene editing of therapeutic T cells.

Clustered regularly interspaced short palindromic repeats (CRISPR)-associated transposons (CASTs) are emerging genome-editing tools that enable RNA-guided DNA integration without inducing double-strand breaks (DSBs). Unlike CRISPR-associated (Cas) nucleases, CASTs use transposon machinery to insert large DNA segments with high precision, potentially reducing off-target effects and bypassing DNA damage responses. CASTs are categorized into classes 1 and 2, each employing distinct mechanisms for DNA targeting and integration. Recent structural insights have elucidated how CASTs recognize target sites, recruit transposases, and mediate insertion. These advances position CASTs as promising tools for genome engineering in bacteria and possibly in mammalian cells. Key challenges remain in enhancing efficiency and specificity, particularly for therapeutic use. Ongoing research aims to evolve CAST systems for precise, large-scale genome editing in human cells.

Base editing enables the high-throughput screening of genetic variants for phenotypic effects. Base editing screens require the design of single guide RNA (sgRNA) libraries to enable either gene- or variant-centric approaches. While computational tools supporting the design of sgRNAs exist, no solution offers versatile and scalable library design enabling all major use cases. Here, we introduce BEscreen, a comprehensive base editing guide design tool provided as a web server (bescreen.ostendorflab.org) and as a command line tool. BEscreen provides variant-, gene-, and region-centric modes to accommodate various screening approaches. The variant mode accepts genomic coordinates, amino acid changes, or rsIDs as input. The gene mode designs near-saturation libraries covering the entire coding sequence of given genes or transcripts, and the region mode designs all possible guides for given genomic regions. BEscreen enables selection of guides by biological consequence, it features comprehensive customization of base editor characteristics, and it offers optional annotation using Ensembl's Variant Effect Predictor. In sum, BEscreen is a highly versatile tool to design base editing screens for a wide range of use cases with seamless scalability from individual variants to large, near-saturation libraries.

CRISPR/Cas gene editing is a highly promising technology for the treatment and even potential cure of genetic diseases. One of the major challenges for its therapeutic use is finding safe and effective vehicles for intracellular delivery of the CRISPR/Cas9 ribonucleoprotein (RNP) complex. In this study, we tested and characterized a series of novel fatty acid-modified versions of a previously reported Cas9 RNP carrier, consisting of a complex of the cell-penetrating peptide (CPP) LAH5 with Cas9 RNP and homology-directed DNA repair templates. Comparative experiments demonstrated that RNP/peptide nanocomplexes showed various improvements depending on the type of fatty acid modification. These improvements included enhanced stability in serum, improved membrane disruption capability and increased transfection efficacy. Cas9 RNP/oleic acid LAH5 peptide nanocomplexes showed the overall best performance for both gene editing and correction. Moreover, Cas9 RNP/oleic acid LAH5 nanocomplexes significantly protected the Cas9 protein cargo from enzymatic protease digestion. In addition, in vivo testing demonstrated successful gene editing after intramuscular administration. Despite the inherent barriers of the tightly organized muscle tissues, we achieved approximately 10 % gene editing in the skeletal muscle tissues when targeting the CAG-tdTomato locus in the transgenic Ai9 Cre-LoxP reporter mouse strain and 7 % gene editing when targeting the Ccr5 gene, without any observable short-term toxicity. In conclusion, the oleic acid-modified LAH5 peptide is an effective delivery platform for direct Cas9/RNP delivery, and holds great potential for the development of new CRISPR/Cas9-based therapeutic applications for the treatment of genetic diseases.

Leukemia, a group of blood cancers, presents a significant global health challenge. Despite advancements in conventional therapies like chemotherapy and immunotherapy, the need for more effective and less toxic treatments remains. Nanotechnology offers a promising avenue for targeted drug delivery and immune modulation in the fight against leukemia. Through the utilization of nanomaterials' special qualities, like their small size, large surface area, and capacity to transport a variety of payloads, scientists are creating novel ways to get around the drawbacks of conventional treatments. These strategies include targeted drug delivery, immune cell activation, and overcoming drug resistance. However, challenges remain in translating these promising nanotechnological approaches into clinical applications. Addressing issues such as toxicity, biodistribution, and regulatory hurdles is crucial for the successful development of nanomedicine for leukemia. In conclusion, nanotechnology offers a promising future for the treatment of leukemia. Continued research and development are essential to unlock the full potential of nanomaterials and improve patient outcomes. The potential of nanotechnology-based strategies to improve the effectiveness of leukemia treatments is explored in this review. We go over the function of different nanomaterials in delivering therapeutic agents to leukemia cells, such as liposomes, polymeric nanoparticles, and inorganic anoparticles. We also investigate the engineering of nanomaterials to influence the immune system and promote anti-tumor reactions.

Hepatitis B virus (HBV) infection is the key cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Currently available anti-HBV drugs are more or less defective owing to the unremovable covalently closed circular DNA (cccDNA). Thus, CRISPR/Cas9 is a promising therapeutic strategy for anti-HBV therapy. Double-strand breaks (DSBs) and uncontrolled genomic rearrangements occur inevitably. In this study, we aimed to use base editors to control HBV infection.

Base editors precisely instal targeted point mutations without requiring DSBs or donor DNA templates, and without relying on homology-directed repair (HDR) or nonhomologous end joining (NHEJ). Adenine base editors (ABEs) and cytosine base editors (CBEs) catalyse A• T to G •C and C• G to T •A conversions, respectively. In this study, to control HBV replication by modifying and inactivating key HBV genes, recently developed CRISPR/Cas-mediated SpRY-ABE8e and CBE4-max were utilised to falsify and invalidate the ATG initiation codons of the S, Pre-S1, PreS2, C, Pre-C, X, and P genes.

The ATG initiation codons of HBV genes were edited by ABE/CBE. The expected point mutations were successfully introduced, resulting in the simultaneous suppression of HBV antigen expression and replication to varying degrees.

Our study focused on clearing HBV using base and provided experimental and theoretical evidence for the treatment of chronic HBV infection. Thus, base editing is a potential strategy for curing CHB by permanently inactivating the integrated DNA and cccDNA without using DSBs.

O6-methylguanine-DNA methyltransferase (MGMT) reverses alkylating-agent-induced methylation by 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) at the O6 position of guanine. MGMT is irreversibly inhibited by O6-benzylguanine (O6BG), while the Pro140Lys (P140K) variant is resistant. Combining the use of O6BG/BCNU with gene transfer of MGMT P140K into hematopoietic stem cells (HSCs) has enabled in vivo enrichment of gene-modified HSCs for therapeutic effect in preclinical studies. However, the P140K substitution cannot reliably be made using currently available gene-editing approaches. Identifying functional MGMT variants that are resistant to inhibitors and amenable to gene editing would enable in vivo enrichment of HSCs edited at both MGMT and a therapeutic locus. We used computational analyses to select putative variants and generated a library of MGMT variant-expressing plasmids (pMGMTs). For our functional screen, we treated MGMT-deficient U251 cells with O6BG and co-transfected them with pMGMT together with a plasmid cocktail including a fluorescent host cell reactivation reporter plasmid (mPlum_O6MeG) for MGMT activity. Flow cytometric analysis of MGMT activity identified active and O6BG-resistant MGMT variants. Treatment with a second MGMT inhibitor, PaTrin-2, confirmed these results. We also found MGMT variants that are detectable in the general population and tumors to be active and O6BG sensitive. Taken together, our findings establish a functional database for MGMT variants and a cell-based platform for screening DNA-repair proteins for unknown functional properties.

Type V-H CRISPR-Cas system, an important subtype of type V CRISPR-Cas systems, has remained enigmatic in terms of its structure and function despite being discovered several years ago. Here, we comprehensively characterize the type V-H CRISPR-Cas system and elucidate its role as a DNA nicking system. The unique CRISPR RNA (crRNA) employed by Cas12h effector protein enables specific targeting of double-stranded DNA (dsDNA), while its RuvC domain is responsible for cleaving the non-target strand (NTS) of dsDNA. We present the structure of Cas12h bound to crRNA and target DNA. Our structural analysis reveals that the RuvC domain possesses a narrow active pocket that facilitates recognition of NTS but potentially hinders access to the target strand. Furthermore, we demonstrate that Cas12h confers adaptive immunity against invading mobile genetic elements through transcriptional gene inhibition. We have engineered an adenine base editor by fusing Cas12h with an adenine deaminase, achieving effective A-to-G substitution.

Precise gene editing with conventional CRISPR/Cas9 is often constrained by low knock-in (KI) efficiencies (≈ 2-20 %) in human induced pluripotent stem cells (hiPSCs) and human embryonic stem cells (hESCs). This limitation typically necessitates labour-intensive manual isolation and genotyping of hundreds of colonies to identify correctly edited cells. Fluorescence- or antibiotic-based enrichment methods facilitate the identification process but can compromise cell viability and genomic integrity. Here, we present a footprint-free editing strategy that combines low-density seeding with next-generation sequencing (NGS) to rapidly identify cell populations containing precisely modified clones. By optimising the transfection workflow and adhering to CRISPR/Cas9 KI design principles, we achieved high average editing efficiencies of 64 % in hiPSCs (introducing a Brugada syndrome-associated variant) and 51 % in hESCs (introducing a neurodevelopmental disorder (NDD)-associated variant). Furthermore, under suboptimal CRISPR design conditions, this approach successfully identified hESC clones carrying a second NDD-associated variant, despite average KI efficiencies below 1 %. Importantly, genomic integrity was preserved throughout subcloning rounds, as confirmed by Sanger sequencing and single nucleotide polymorphism (SNP) array analysis. Hence, this NGS-based enrichment strategy reliably identifies desired KI clones under both optimal and challenging conditions, reducing the need for extensive colony screening and offering an effective alternative to fluorescence- and antibiotic-based selection methods.

The advent of genome-editing technologies, particularly the RNA-guided the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated system (Cas) 9, which originates from prokaryotic CRISPR/Cas adaptive immune mechanisms, has revolutionized molecular biology. Renowned for its simplicity, cost-effectiveness, and capacity for multiplexed gene editing, CRISPR/Cas9 has emerged as the most versatile and widely adopted genome-editing platform. Its applications span fundamental research, biotechnology, medicine, and therapeutics. This review highlights recent advancements in CRISPR-based technologies, focusing on CRISPR/Cas9, CRISPR/Cas12a, and CRISPR/Cas12f. It emphasizes precision editing methods like base editing and prime editing, which enable targeted nucleotide changes without double-strand breaks. The specificity of these tools, including on-target accuracy and off-target risks, is critically evaluated. Additionally, recent preclinical and clinical efforts to treat diseases such as cancer and sickle cell disease using CRISPR are summarized. Finally, the challenges and future directions of CRISPR-mediated gene therapy are discussed, emphasizing its potential to integrate with other molecular approaches to address unmet medical needs.

This review summarizes recent advancements in the research of autism spectrum disorders (ASD), emphasizing genetic underpinnings and their implications for neurodevelopment and cognitive functions. It explores both syndromic and nonsyndromic ASD, highlighting the discovery of critical ASD-related genes and their mechanistic roles as revealed by studies using genetically engineered mouse and non-human primate models. While these models have shed light on the potential of synaptic dysfunction to disrupt brain development, they also underscore the challenges of replicating complex cognitive dysfunctions observed in ASD. Recent successes in gene therapy, particularly through innovative approaches like gene replacement and base editing, offer promising pathways for addressing genetic anomalies in ASD. These therapeutic strategies, underscored by clinical trials and cutting-edge genetic manipulation techniques, pave the way for potential interventions that could profoundly impact ASD management and treatment.

Sickle cell disease (SCD) is a hereditary blood disorder caused by a specific mutation in the β-globin gene, leading to the production of hemoglobin S, which deforms red blood cells, causing occlusion in small blood vessels. This results in pain, anemia, organ damage, infections, and increased stroke risk. Treatment options, including disease-modifying therapies and curative hematopoietic stem cell transplants, have limited accessibility. Recently, autologous gene therapy has emerged as a promising curative option, particularly for SCD. Gene editing techniques such as CRISPR, base editing, and prime editing offer potential to correct this mutation. In this review, we discuss recent preclinical studies and clinical trials of gene and cell therapies, focusing on the progress of FDA-approved treatments like Lyfgenia and Casgevy. We also examine the many challenges, including accessibility, safety, and long-term efficacy, which continue to shape the future of SCD gene therapy.

Adenine base editors (ABEs) enable the conversion of A•T to G•C base pairs. Since the sequence of the target locus influences base editing efficiency, efforts have been made to develop computational models that can predict base editing outcomes based on the targeted sequence. However, these models were trained on base editing datasets generated in cell lines and their predictive power for base editing in primary cells in vivo remains uncertain.

In this study, we conduct base editing screens using SpRY-ABEmax and SpRY-ABE8e to target 2,195 pathogenic mutations with a total of 12,000 guide RNAs in cell lines and in the murine liver. We observe strong correlations between in vitro datasets generated by ABE-mRNA electroporation into HEK293T cells and in vivo datasets generated by adeno-associated virus (AAV)- or lipid nanoparticle (LNP)-mediated nucleoside-modified mRNA delivery (Spearman R = 0.83-0.92). We subsequently develop BEDICT2.0, a deep learning model that predicts adenine base editing efficiencies with high accuracy in cell lines (R = 0.60-0.94) and in the liver (R = 0.62-0.81).

In conclusion, our work confirms that adenine base editing holds considerable potential for correcting a large fraction of pathogenic mutations. We also provide BEDICT2.0 - a robust computational model that helps identify sgRNA-ABE combinations capable of achieving high on-target editing with minimal bystander effects in both in vitro and in vivo settings.

Gene therapy development, re-engineering, and application to patients hold promise to revolutionize medicine, including therapies for disorders of the brain. Advances in delivery modalities, expression regulation, and improving safety profiles are of critical importance. Additionally, each inherited disorder has its own unique characteristics as to regions and cell types impacted and the temporal dynamics of that impact that are essential for the design of therapeutic design strategies. Here, we review the current state of the art in gene therapies for inherited brain disorders, summarizing key considerations for vector delivery, gene addition, gene silencing, gene editing, and epigenetic editing. We provide examples from animal models, human cell lines, and, where possible, clinical trials. This review also highlights the various tools available to researchers for basic research questions and discusses our views on the current limitations in the field.

Forty years after the dystrophin gene was cloned, significant progress has been made in developing gene therapy approaches for Duchenne muscular dystrophy (DMD). The disorder has presented numerous challenges, including the enormous size of the gene (2.2 MB), the need to target muscles body wide, and immunogenic issues against both vectors and dystrophin. Among human genetic disorders, DMD is relatively common, and the genetics are complicated since one-third of all cases arise from a spontaneous new mutation, resulting in thousands of independent lesions throughout the locus. Many approaches have been pursued in the goal of finding an effective therapy, including exon skipping, nonsense codon suppression, upregulation of surrogate genes, gene replacement, and gene editing. Here, we focus specifically on methods using AAV vectors, as these approaches have been tested in numerous clinical trials and are able to target muscles systemically. We discuss early advances to understand the structure of dystrophin, which are crucial for the design of effective DMD gene therapies. Included is a summary of efforts to deliver micro-, mini-, and full-length dystrophins to muscles. Finally, we review current approaches to adapt gene editing to the enormous DMD gene with prospects for improved therapies using all these methods.

The molecular complexity of bladder cancer restricts reliance on single-feature or single-gene targeted therapies, necessitating integrated individualized treatments and multi-gene interventions. In this study, we introduced the CRISPR/dCas9-SAM system to BCa treatment, known for its high specificity, low off-target effects, and reduced genetic toxicity, making it ideal for multiplexed gene activation at minimal cost-just 20 nucleotides per target. However, despite its potential in complex gene therapy and cellular engineering, challenges persist due to safety concerns associated with viral vectors and the risk of off-target effects during in vivo delivery, necessitating the development of new vectors. Herein, we reported pH-sensitive hollow mesoporous silica nanoparticles modified with PLZ4 ligands (PLZ4-Lip@AMSN/CRISPR/dCas9-SAM, PLACS NPs) for precise targeting of bladder tumors and co-delivery of CRISPR/dCas9-SAM system. With good stability and high plasmid loading capacity, they efficiently co-delivered dCas9-VP64, MS2-P65-HSF1, and sgRNA. Compared to Lipofectamine 3000, these nanoparticles exhibited superior lysosomal escape capability, significantly enhancing transfection efficiency in bladder cancer cells. Moreover, PLACS NPs simultaneously activated the expression of four target genes, inhibiting proliferation and migration, and promoting apoptosis in bladder cancer cells. In vivo, they achieved efficient gene editing at tumor sites, significantly inhibiting bladder tumor growth. Real-time imaging revealed their substantial accumulation and prolonged retention at bladder tumor sites without significant liver targeting and major organ damage, showcasing good specificity and biosafety. This study overcomes in vivo delivery challenges of multi-component CRISPR/dCas9 systems, enabling precise gene editing and anti-tumor effects, presenting an innovative strategy for targeted therapy in bladder cancer treatment. STATEMENT OF SIGNIFICANCE: This study introduces a newly-developed approach to address key challenges in bladder cancer gene therapy, namely low gene upregulation efficiency, limited targeting specificity, and inefficient nucleic acid delivery. By integrating the CRISPR/dCas9-SAM system, we achieve highly specific gene activation with minimal off-target effects, enabling the addition of treatment targets with just 20 nucleotides per target. To improve bladder cancer targeting, we developed PLACS NPs, a mesoporous silica nanoparticle system that enhances plasmid delivery, transfection efficiency, and endosomal escape. This system shows good tumor targeting and significant anti-tumor effects in bladder cancer, without significant liver targeting and major organ toxicity, offering promising therapeutic potential and broad clinical applications.

The application of genome editing tools in Hymenoptera has transformative potential for functional genetics and understanding their unique biology. Hymenoptera comprise one of the most diverse Orders of animals, and the development of methods for efficiently creating precise genome modifications could have applications in conservation, pest management and agriculture. To date, sex determination, DNA methylation, taste and smell sensory systems as well as phenotypic markers have been selected for gene editing investigations. From these data, insights into eusociality, the nature of haplodiploidy and the complex communication systems that Hymenoptera possess have provided an understanding of their evolutionary history that has led them to become so diverse and successful. Insights from these functional genetics analyses have been supported by the ever-improving suite of CRIPSR tools and further expansion will allow more specific biological hypotheses to be tested and applications beyond the lab. Looking ahead, genome editing tools have potential for Hymenopteran applications in modifying biocontrol agents of agricultural pests and for use in managing invasive species through the development of technologies such as gene drives. This review provides accessibility to information regarding the status of Hymenopteran genome editing, intending to support the considered development of CRISPR tools in novel species as well as innovation and refinement of methods in species in which it has already been achieved.

Prime editors (PEs) have emerged as transformative tools for precision genome engineering, yet their broader application remains constrained by incomplete understanding of repair mechanisms. In this study, it is found that an increase in the methylation level of the CpG sequence on the newly generated strand can increase PE efficiency and that de novo DNA methyltransferases (DNMT3A/3B) are involved in the PE repair pathway. On the basis of these novel findings, the development of an episomal element-driven PE system (epiPE) achieved through the use of EBNA1/oriP are presented, which increases methylation levels around target sites and prolongs PE expression. A comparative analysis with canonical PE systems, including PE2, lentiPE2, and PE4max, reveals that the epiPE2 system significantly enhances editing efficiency while maintaining minimal insertion and deletion (indels) rates. Specifically, comparing to PE2, the epiPE2 system demonstrated an efficiency enhancement of 2.0 to 38.2-fold. In addition, the epiPE2 system is capable of efficient multiplex precise gene editing at up to 10 genetic loci in human cells. In conclusion, this findings increase the understanding of the PE repair mechanism, and presents the epiPE2 system as an efficient and multiplex-capable prime editing tool with potential applications in both basic research and translational studies.

The continued development of novel genome editors calls for a universal method to analyze their off-target effects. Here we describe a versatile method, called Tracking-seq, for in situ identification of off-target effects that is broadly applicable to common genome-editing tools, including Cas9, base editors and prime editors. Through tracking replication protein A (RPA)-bound single-stranded DNA followed by strand-specific library construction, Tracking-seq requires a low cell input and is suitable for in vitro, ex vivo and in vivo genome editing, providing a sensitive and practical genome-wide approach for off-target detection in various scenarios. We show, using the same guide RNA, that Tracking-seq detects heterogeneity in off-target effects between different editor modalities and between different cell types, underscoring the necessity of direct measurement in the original system.

The miniature RNA-guided endonuclease IscB, as the evolutionary progenitor of Cas9, is attracting increased attention for genome editing due to its compact size and suitability for in vivo delivery. However, the poor editing efficiency of IscB in eukaryotic cells presents a significant challenge to its widespread application in precise site-specific human genome editing. In this study, we employed structure-guided rational design and protein engineering to optimize OgeuIscB, resulting in the identification of enIscB-F138R, which further enhanced editing activity up to 3.49-fold in mammalian cells compared to the high-activity OgeuIscB variant enIscB. Furthermore, we engineered an enIscB-F138R nickase-based adenine base editor, termed miABE-F138R, exhibiting enhanced base editing efficiency relative to miABE. To illustrate the practical applications of miABE-F138R, we applied it to rectify the prevalent R560C mutation in Pde6β associated with autosomal recessive retinitis pigmentosa, resulting in a significant improvement in activity compared to miABE. In conclusion, enIscB-F138R and miABE-F138R offer adaptable platforms for genome editing with potential significance in future biomedical applications.

Transposable elements (TEs) are mobile repetitive nucleic acid sequences that have been incorporated into the genome through spontaneous integration, accounting for almost 50% of human DNA. Even though most TEs are no longer mobile today, studies have demonstrated that they have important roles in different biological processes, such as ageing, embryonic development, and cancer. TEs influence these processes through various mechanisms, including active transposition of TEs contributing to ongoing evolution, transposon transcription generating RNA or protein, and by influencing gene regulation as enhancers. However, how TEs interact with the immune system remains a largely unexplored field. In this Perspective, we describe how TEs might influence different aspects of the immune system, such as innate immune responses, T cell activation and differentiation, and tissue adaptation. Furthermore, TEs can serve as a source of neoantigens for T cells in antitumour immunity. We suggest that TE biology is an important emerging field of immunology and discuss the potential to harness the TE network therapeutically, for example, to improve immunotherapies for cancer and autoimmune and inflammatory diseases.

The advent of genome editing has kindled the hope to cure previously uncurable, life-threatening genetic diseases. However, whether this promise can be ultimately fulfilled depends on how efficiently gene editing agents can be delivered to therapeutically relevant cells. Over time, viruses have evolved into sophisticated, versatile, and biocompatible nanomachines that can be engineered to shuttle payloads to specific cell types. Despite the advances in safety and selectivity, the long-term expression of gene editing agents sustained by viral vectors remains a cause for concern. Cell-derived vesicles (CDVs) are gaining traction as elegant alternatives. CDVs encompass extracellular vesicles (EVs), a diverse set of intrinsically biocompatible and low-immunogenic membranous nanoparticles, and virus-like particles (VLPs), bioparticles with virus-like scaffold and envelope structures, but devoid of genetic material. Both EVs and VLPs can efficiently deliver ribonucleoprotein cargo to the target cell cytoplasm, ensuring that the editing machinery is only transiently active in the cell and thereby increasing its safety. In this review, we explore the natural diversity of CDVs and their potential as delivery vectors for the clustered regularly interspaced short palindromic repeats (CRISPR) machinery. We illustrate different strategies for the optimization of CDV cargo loading and retargeting, highlighting the versatility and tunability of these vehicles. Nonetheless, the lack of robust and standardized protocols for CDV production, purification, and quality assessment still hinders their widespread adoption to further CRISPR-based therapies as advanced "living drugs." We believe that a collective, multifaceted effort is urgently needed to address these critical issues and unlock the full potential of genome-editing technologies to yield safe, easy-to-manufacture, and pharmacologically well-defined therapies. Finally, we discuss the current clinical landscape of lung-directed gene therapies for cystic fibrosis and explore how CDVs could drive significant breakthroughs in in vivo gene editing for this disease.

The CRISPR (clustered regularly interspaced short palindromic repeats) system has emerged as a revolutionary gene-editing tool with immense potential in gene therapy, functional genomics, and beyond. However, achieving precise spatiotemporal control of gene editing in specific cells and tissues while effectively mitigating potential risks, such as off-target effects, remains a key challenge for its clinical translation. To overcome these limitations, researchers have developed innovative strategies based on chemical modifications of oligonucleotides to enhance the precision, efficiency, and controllability of CRISPR/Cas9-mediated gene editing. By introducing conditional responsive elements, such as photosensitive groups, small-molecule responsive units, and supramolecular structures, they have successfully achieved precise spatiotemporal and dose-dependent regulation of CRISPR/Cas9 function. This review provides a comprehensive overview of recent advancements in gRNA regulation strategies based on chemical modifications of oligonucleotides, discussing their applications in improving the efficiency, specificity, and controllability of CRISPR/Cas9 editing. We also highlight the challenges associated with the conditional control of gRNA and offer insights into future directions for the chemical regulation of gRNA to further advance CRISPR/Cas9 technology.

Gene editing (GE) technology is a genetic manipulation technique based on artificial nucleases that enables the precise modification of DNA or RNA. With the development of technology, GE in disease treatment is becoming increasingly widespread, playing an essential role in haematology, cancer, and neurological disorders (ND). This review describes the principles, advantages, and limitations of four GE technologies, focusing on the fourth generation of GE (next-generation GE). The next-generation GE technology breaks the limitations of traditional GE technology, makes GE more precise and stable, and broadens the scope of gene technology applications. Additionally, this review explores the latest gene therapy strategies for ND, focusing on the application of next-generation GE technologies to examine the prospects for the application of GE technologies. This study discusses and analyses the great advantages and potential of GE technology for treating ND and elucidates the shortcomings of GE in this field.

CRISPR-Cas9 is a powerful genome-editing technology that can precisely target and cleave DNA to induce double-strand breaks (DSBs) at almost any genomic locus. While this versatility holds tremendous therapeutic potential, the predominant cellular pathway for DSB repair-non-homologous end-joining (NHEJ)-often introduces small insertions or deletions that disrupt the target site. In contrast, homology-directed repair (HDR) utilizes exogenous donor templates to enable precise gene modifications, including targeted insertions, deletions, and substitutions. However, HDR remains relatively inefficient compared to NHEJ, especially in postmitotic cells where cell cycle constraints further limit HDR. To address this challenge, numerous methodologies have been explored, ranging from inhibiting key NHEJ factors and optimizing donor templates to synchronizing cells in HDR-permissive phases and engineering HDR-enhancing fusion proteins. These strategies collectively aim to boost HDR efficiency and expand the clinical and research utility of CRISPR-Cas9. In this review, we discuss recent advances in manipulating the balance between NHEJ and HDR, examine the trade-offs and practical considerations of these approaches, and highlight promising directions for achieving high-fidelity genome editing in diverse cell types.

CRISPR-Cas9 has revolutionized genome engineering by allowing precise introductions of DNA double-strand breaks (DSBs). However, genome engineering in bacteria is still a complex, multi-step process requiring a donor DNA template for repair of DSBs. Prime editing circumvents this need as the repair template is indirectly provided within the prime editing guide RNA (pegRNA). Here, we developed make-or-break Prime Editing (mbPE) that allows for precise and effective genetic engineering in the opportunistic human pathogen Streptococcus pneumoniae. In contrast to traditional prime editing in which a nicking Cas9 is employed, mbPE harnesses wild type Cas9 in combination with a pegRNA that destroys the seed region or protospacer adjacent motif. Since most bacteria poorly perform template-independent end joining, correctly genome-edited clones are selectively enriched during mbPE. We show that mbPE is RecA-independent and can be used to introduce point mutations, deletions and targeted insertions, including protein tags such as a split luciferase, at selection efficiencies of over 93%. mbPE enables sequential genome editing, is scalable, and can be used to generate pools of mutants in a high-throughput manner. The mbPE system and pegRNA design guidelines described here will ameliorate future bacterial genome editing endeavors.

Intestinal microbiota members of the Bifidobacterium genus are increasingly explored as probiotics and therapeutics. However, the paucity of genetic tools and the widespread restriction modification (RM) systems in Bifidobacterium limit our ability to genetically manipulate these bacteria. Here we established a CRISPR-Cas9 cytosine base editor system (cBEST) for portable genome editing in bifidobacteria. Harboring different promoters characterized in this study, these cBEST plasmids showed a range of editing efficiencies in different strains and genomic contexts, highlighting the importance of fine-tuning base editor and sgRNA expression. Additionally, we showed that disruption or bypass of RM systems dramatically improved editing efficiencies in otherwise hard-to-edit genomic loci and Bifidobacterium strains. Notably, we demonstrated the use of RM-disrupted Bifidobacterium longum strains for simultaneous assembly, amplification, and methylation of the all-in-one editing plasmids, greatly streamlining the workflow for high-efficiency base editing. Last but not least, we showed the portability of cBESTs using the same editing construct to disrupt a conserved metabolic gene in multiple Bifidobacterium species. Looking ahead, the ability to efficiently edit and engineer bifidobacterial genomes will give rise to new opportunities for research and applications toward improving human health.IMPORTANCEThe ability to genetically manipulate specific genes and biological pathways in Bifidobacterium is essential to unlocking their probiotic and therapeutic potential in human health applications. The DNA double-strand break-free CRISPR-Cas9 cytosine base editor system established in this work allows portable and efficient base editing in Bifidobacterium spp. We further showed that bypass of restriction modification systems significantly improved base editing efficiency, especially for hard-to-edit genomic loci and strains. This expanded Bifidobacterium genome editing toolbox should facilitate mechanistic investigations into the roles of Bifidobacterium in host physiology and disease.

Base editing offers high potential for treating genetic diseases, particularly those with limited treatment options. Retinoschisis, an X-linked retinal disease causing progressive vision loss, currently lacks effective therapies. We identified the c.422G>A (p.Arg141His) variant of the RS1 gene in six male patients with retinoschisis and generated a humanized mouse model harboring this variant, which mimicked the disease phenotype. By testing adenine base editors and single-guide RNAs, we identified an optimal combination of high editing efficiency and low bystander editing. Intravitreal injection of adeno-associated viral vectors encoding this adenine base editor achieved ∼40% editing efficiency in all retinal cells, restored retinal layer integrity, and preserved visual functions in 2-week-old male hemizygous mice. These mice exhibited retinal layer splitting at baseline, further validating the model. This study demonstrates a strategy for identifying effective base editing tools for clinical use through the preclinical evaluation of humanized mouse lines with patient-derived mutations and highlights their applicability in treating genetic diseases.

Transposable elements (TEs) constitute a large portion of many plant genomes and play important roles in regulating gene expression and in driving genome evolution and crop domestication. Despite advances in understanding the functions and mechanisms of TEs, a comprehensive review of their integrated knowledge and cutting-edge biotechnological applications of TEs is still needed. We provide a thorough overview that connects discoveries, mechanisms, and technologies associated with plant TEs. We discuss the identification and function of TEs driven by functional genomics, epigenetic regulation of TEs, and utilization of active TEs in plant functional genomics and genome engineering. In summary, expanding the knowledge and application of TEs will be beneficial to crop breeding and plant synthetic biology in the future.

After Cas12a cleaves its DNA target, it generates a DNA double strand break (DSB) with two compatible 5'-staggered ends. The Cas12a-gRNA complex remains at the protospacer adjacent motif (PAM)-proximal end (PPE) while releasing the PAM-distal end (PDE). The effects of this asymmetric retention on DSB repair are currently unknown.

Post-cleavage retention of LbCas12a at PPEs suppresses the recruitment of classical non-homologous end joining (c-NHEJ) core factors, leading to longer deletions at PPEs compared to PDEs. This asymmetry in c-NHEJ engagement results in approximately tenfold more accurate ligation between two compatible PDEs induced by paired LbCas12a than ligation involving a compatible PPE. Moreover, ligation to a given end of SpCas9-induced DSBs demonstrates more efficient ligation with a PDE from Cas12a-induced DSBs than with a PPE. In LbCas12a-induced NHEJ-mediated targeted integration, only two compatible PDEs from LbCas12a-induced DSBs-one from donor templates and the other from target sites-promote accurate and directional ligation. Based on these findings, we developed a strategy called Cas12a-induced PDE ligation (CIPDEL) for NHEJ-mediated efficient and precise gene correction and insertion.

The asymmetric retention of CRISPR-LbCas12a at DSB ends suppresses c-NHEJ at PPEs, not at PDEs. This unique repair mechanism can be utilized in the CIPDEL strategy, offering a potentially better alternative for homology-directed targeted integration.