Safe Harbor Gene Editing for Lasting Therapies

Directed evolution of hyperactive integrases for site specific insertion of transgenes For decades, scientists have dreamt of a future where genetic diseases, such as the blood clotting disorder hemophilia, could be a thing of the past. Gene therapy, the idea of fixing faulty genes with healthy ones, has held immense promise. But a major hurdle has been finding a safe and efficient way to deliver those genes. Researchers have now made a significant breakthrough in gene editing technology that could revolutionize how we treat genetic diseases. The ability to deliver large transgenes to a single genomic sequence with high efficiency would accelerate biomedical interventions. Current methods suffer from low insertion efficiency and most rely on undesired double-strand DNA breaks. Serine integrases catalyze the insertion of large DNA cargos at attachment (att) sites. By targeting att sites to the genome using technologies such as prime editing, integrases can target safe loci while avoiding double-strand breaks. We developed a method of phage-assisted continuous evolution we call IntePACE, that we used to rapidly perform hundreds of rounds of mutagenesis to systematically improve activity of PhiC31 and Bxb1 serine integrases. Novel hyperactive mutants were generated by combining synergistic mutations resulting in integration of a multi-gene cargo at rates as high as 80% of target chromosomes. Hyperactive integrases inserted a 15.7 kb therapeutic DNA cargo containing von Willebrand Factor. This technology could accelerate gene delivery therapeutics and our directed evolution strategy can easily be adapted to improve novel integrases from nature. https://lnkd.in/gDAy4Nxy https://lnkd.in/gmt4TZ7D

American researchers have unveiled STITCHR in Nature, a novel gene-editing tool that enables the precise insertion of entire therapeutic genes into specific genomic locations without introducing unwanted mutations. Unlike traditional CRISPR systems, which typically correct single mutations and often face targeting limitations, STITCHR offers a "one-and-done" solution by inserting full genes. It may be a game-changing approach for treating diseases caused by a wide range of mutations, such as cystic fibrosis. STITCHR, short for Specific Target-Primed Insertion Through Targeted CRISPR Homing of Retroelements, harnesses enzymes derived from retrotransposons, genetic elements also known as "jumping genes", to guide gene integration with high specificity. Notably, the system can be delivered entirely in RNA form, simplifying logistics compared to approaches that require both RNA and DNA components. This advancement marks a major step forward in gene therapy, offering a promising strategy to treat diverse genetic disorders by replacing faulty genes in their entirety.

🧬 This company claims world-first AI models for programmable gene insertion! That’s the headline from Basecamp Research last week, and if it holds up, it’s an important signal for genetic medicine. Programmable insertion of large DNA sequences at precise locations in the human genome has been a decades-long goal. CRISPR revolutionized gene editing, but it typically relies on creating double-strand breaks and is better suited to smaller edits. Large, targeted insertions, especially in defined “safe harbour” sites, have remained technically constrained. Basecamp’s aiPGI™ platform, powered by its EDEN evolutionary foundation models developed with NVIDIA, is positioned as a step beyond that. Trained on more than 10 trillion tokens of evolutionary DNA from over a million newly discovered species, the models aim to learn deep evolutionary constraints well enough to design novel insertion enzymes from sequence context alone. In their reported lab results, the system generated active insertion proteins for 100% of tested disease-relevant genomic sites, using only the target DNA sequence as input. Technically, that’s the interesting part. This is conditioning a large biological model on a genomic locus and generating a bespoke insertion protein, not justscreening or optimizing existing editors. The largest EDEN model was trained at GPT-4–class compute scale, putting it among the most computationally intensive biological models to date. They also showed cross-domain capability: the same model designed antimicrobial peptides with a 97% lab-confirmed hit rate, including candidates active against multidrug-resistant pathogens. That kind of generalization is what you’d expect from a true biological foundation model, not a single-task tool. If reproducible and scalable, programmable gene insertion without relying on conventional break-and-repair workflows could reshape how we approach cell and gene therapy design. Subscribe to The Biotech Edge for weekly industry signals in the frontier techbio space: https://lnkd.in/d7Rj_MHy Image credit: Basecamp Research

🟥 In Vivo CRISPR Delivery Using Engineered Nanoparticles for Tissue-Specific Gene Correction CRISPR-based gene editing technology has revolutionized genome engineering, but one of its biggest challenges remains efficient and safe in vivo delivery. Traditional approaches, such as viral vectors, present risks of immune response, genomic integration, and limited payload capacity. To overcome these limitations, researchers are developing engineered nanoparticles for tissue-specific, non-viral CRISPR delivery, providing a safer and more precise approach to in vivo gene correction. Nanoparticle-based CRISPR delivery systems are designed to encapsulate CRISPR-Cas components (mRNA, RNPs, or plasmids) and efficiently deliver them to target cells. Lipid nanoparticles (LNPs) have shown promising results in delivering CRISPR therapeutics for liver diseases such as transthyretin amyloidosis (ATTR), where targeted gene correction has been achieved with high efficiency. In addition, polymer- and peptide-based nanoparticles are being optimized to enhance stability, minimize degradation, and improve tissue targeting. A major advantage of engineered nanoparticles is their ability to be functionalized for tissue-specific targeting. By modifying the surface of nanoparticles with ligands, peptides, or antibodies, researchers can direct CRISPR delivery to specific organs, such as the brain, lungs, or muscles. This approach improves editing precision while minimizing off-target effects, making it particularly valuable for treating genetic diseases that affect multiple tissues. In addition to specificity, nanoparticles enhance the safety of CRISPR delivery by avoiding permanent genomic integration and reducing the risk of immune activation. Unlike viral vectors, nanoparticles allow transient expression of CRISPR components, reduce unwanted mutations, and make gene editing reversible when necessary. This makes them an attractive option for clinical applications in regenerative medicine and gene therapy. With advances in AI-driven nanoparticle design, improved stability, and real-time delivery tracking, in vivo CRISPR therapies will become more efficient and widely applicable. Engineered nanoparticles have great potential for safe, precise, and effective gene correction, paving the way for the next generation of personalized medicine.   References [1] San Hae Im et al., Journal of Nanobiotechnology 2024 (https://lnkd.in/eZibegXe) [2] Tuo Wei et al., Nature Communications 2020 (https://lnkd.in/e2M7pq5C) #CRISPR #GeneTherapy #Nanomedicine #PrecisionMedicine #GenomeEngineering #BiotechInnovation #Nanoparticles #GeneticTherapy #BiomedicalBreakthroughs #SyntheticBiology #CSTEAMBiotech

Remarkably high insertion efficiency (80% is way better than CRISPR-Cas9): "...we engineer and characterize an all-RNA system for transgene insertion. We substantially reduce the system’s size and insertion scars by eliminating unnecessary R2 sequences on the donor. We further improve the integration efficiency by chemically modifying the 5′ end of the donor RNA and optimizing delivery, creating a compact system that achieves over 80% integration efficiency in several human cell lines." "Here, we show that the R2 element from the zebra finch Taeniopygia guttata (R2Tg) is active in human cells and can be engineered for efficient transgene insertion. We biochemically characterize the retrotransposon R2Tg and report its cryo-electron microscopy (cryo-EM) structure as it initiates TPRT, highlighting key differences from the more extensively studied R2 from the silk moth Bombyx mori (R2Bm). Leveraging these insights, we adapt R2Tg to integrate non-R2 cargo RNA in mammalian cells and systematically identify and resolve efficiency-limiting factors. The engineered system provides a compact and chemically modified all-RNA system that performs robustly in multiple mammalian cell types." "Looking ahead, we anticipate that the biochemical, structural, and engineering insights from our study will help guide the future development of R2Tg-based knock-in systems. This all-RNA system is uniquely suited for sensitive primary cells, enabling delivery of both the editor and donor with one LNP without the need for viral vectors, while minimizing the risks of innate immune response, random genomic integration, and prolonged exposure to DNA editors commonly associated with DNA-based systems7–9,76,77. These strengths can be leveraged, for example, to introduce chimeric antigen receptors (CAR) into T cells78. Our study also highlights the potential of an allRNA system to leverage the rapid advances in RNA delivery and modification technologies47,48,77. As the field of RNA therapeutics continues to evolve, new improvements can be rationally incorporated to broaden the application of our system." https://lnkd.in/eJkeX4Qw

EvoCAST system is officially pressed! David Liu's team utilized a continuous evolution platform to improve CASTs (CRISPR-associated transposases) activity, yielding an evolved CAST with hundreds of fold increased activity in human cells. The advantages of evoCAST—including its simple programmability, single-step integration mechanism, and avoidance of genomic double-strand breaks—make it well-suited for many applications in the life sciences and therapeutics. EvoCAST achieved 10 to 30% integration efficiencies across 14 genomic targets in human cells, representing a 420-fold average improvement over wild-type CAST. EvoCAST supported large DNA cargoes >10 kb and mediated the integration of several therapeutic payloads at disease-relevant genomic sites, including safe harbor loci, sites for cancer immunotherapy engineering, and genes implicated in loss-of-function genetic diseases. EvoCAST also performed targeted integration in multiple human cell types, including primary human fibroblasts, and exhibited high product purity, with no detected insertions and deletions (indels), predominantly unidirectional cargo insertion, single–base pair precision of integration, and low levels of off-target integration. PACE-evolved CASTs mediate efficient, programmable gene integration in human cells: Science. 15 May 2025. Vol 388, Issue 6748 https://lnkd.in/eEbWWadb