CMN Weekly (18 October 2024) - Your Weekly CRISPR Medicine News

Top picks

• Using a PAMless SpRY base editor, American researchers have corrected mutations in hematopoietic stem cells that cause X-linked chronic granulomatous disease (X-CGD). The adenine editor ABE8e-SpRY achieved 70% correction of the CYBB c.676C>T mutation, surpassing previous CRISPR methods. Off-target effects were minimal, and edited cells persisted post-transplantation.
• Researchers at ChristianaCare Health System have developed CRISPR-Cas strategies to target melanoma cells with BRAF V600E/NRAS Q61K mutations, which cause resistance to BRAF inhibitors (BRAFi). Using mutation-specific AsCas12a and SaCas9 systems, they selectively edited the NRAS Q61K mutation, re-sensitising resistant A375 cells to BRAFi treatment.

Research

• THP1 is a new lipid nanoparticle (LNP) featuring a tetrahydropyrimidine backbone for efficient mRNA delivery. THP1 LNPs demonstrated high transfection efficiency, sustained protein expression, and low toxicity in vivo. They also enabled gene editing in liver tissues using CRISPR-Cas9 in a mouse model.
• Japanese researchers have engineered branched ionisable lipids for delivering CRISPR-Cas ribonucleoproteins (RNPs) to the liver, achieving over 98% reduction in transthyretin protein with minimal toxicity. The lipid’s carbon number and branching position were critical to its success, with optimal formulations showing a unique “flower-like structure” and apolipoprotein E-independent accumulation in hepatocytes.
• Researchers in South Korea have developed a cadmium selenide (CdSe) quantum dot (Qdot) system to deliver CRISPR-Cas9 for gene editing via LNPs in microglia, the brain’s immune cells. This system offers potential advancements in therapies for neuroinflammation and neurodegenerative diseases. Compared to commercial systems, Qdots showed higher specificity and reduced cytotoxicity.
• Researchers in Iran have developed a CRISPR-Cas9 platform using an intelligent guide RNA circuit that senses internal cellular RNA to regulate gene activity. The system, featuring two toehold switches, activates CrRNA release in response to specific trigger RNA, enabling precise targeting of a reporter gene (luciferase).
• Jennifer Doudna and colleagues have engineered a thermostable Cas9 variant, iGeoCas9, which dramatically enhances genome editing efficiency in mammalian tissues, particularly the lungs and liver when delivered via lipid nanoparticles (LNPs). The researchers used LNPs to deliver iGeoCas9 RNPs in vivo to mouse liver and lung tissues and achieved 16-37% editing efficiency in single-dose treatments.
• Researchers in China have developed sarID, a Cas13-based method for detecting RNA-RNA interactions. The technique addresses the gap in understanding long non-coding RNA (lncRNA) partners. Using sarID on NEAT1, over 1,000 new binding transcripts were identified. The method also revealed interactions for XIST, MALAT1, NBR2, and DANCR.

Industry

• Poseida Therapeutics has received a $15 million milestone payment from Roche through the nomination of a new dual CAR-T candidate for hematologic cancers, including multiple myeloma. Using Poseida’s non-viral system, it inserts two CARs into T stem cell memory cells.
• Intellia Therapeutics will review new data from the Phase 2 study of NTLA-2002 in a webcast on Thursday, October 24. Leveraging CRISPR-Cas technology, NTLA-2002 is designed to prevent hereditary angioedema (HAE) attacks by inactivating the kallikrein B1 (KLKB1) gene, which encodes for prekallikrein, the kallikrein precursor protein.

CRISPR screens

• An American study uses CRISPR-Cas9 screens to identify genes controlling human pluripotent stem cell fitness and differentiation. It highlights mitochondrial, metabolic, and chromatin regulators as key to pluripotency, with a core network of chromatin factors influencing both cell fitness and identity.

Detection

• A new CRISPR-Cas13a guide RNA design method enhances nucleic acid detection by generating artificial sequences rather than relying on natural ones. This approach, developed using machine learning algorithms, improves the sensitivity and specificity for detecting diverse pathogens, outperforming traditional guide design methods.
• Chinese researchers have developed a CRISPR-based transistor biosensor for detecting single nucleotide variants (SNVs) in viral RNA. Using engineered Cas13a to capture SNV RNA on a graphene surface, the biosensor generates a rapid electrical signal without amplification and detects RNA down to 5 copies per 100 μL.
• A new study explores the trans-cleavage activities of Cas12a, Cas12f1, and Cas13a in molecular diagnostics. It reveals that Cas13a can target DNA directly, enhancing detection sensitivity for single-base mismatches. Both Cas12a and Cas13a are activated by diverse RNA:DNA and RNA:RNA duplexes, while Cas12f1 exhibits intrinsic RNase activity without activation.
• A new electrochemical biosensor using a CRISPR-Cas12a system can detect as few as 2 cells/mL folate receptor-positive circulating tumour cells (CTCs) in breast cancer. Folate-functionalised magnetic beads capture CTCs, followed by mild reduction to expose sulfhydryl groups, enabling signal amplification through CRISPR-Cas12a activity.

Reviews

• The future of genetic medicines delivered via targeted lipid nanoparticles to leukocytes. This review discusses the crucial aspects of designing targeted lipid nanoparticles (tLNPs) and highlights the considerations for choosing an appropriate bioconjugation strategy and targeting moiety.
• CRISPR–Cas9 delivery strategies for the modulation of immune and non-immune cells. This review summarises ex vivo and in vivo strategies for delivering CRISPR–Cas9 components to both non-immune and immune cells and discusses the principles and challenges of immune system modulation using CRISPR–Cas9 genome editing technology.
• Targeting mRNA-coding genes in prostate cancer using CRISPR/Cas9 technology, with a particular focus on androgen receptor signalling. This review summarises the most recent progress in the application of the CRISPR/Cas9 strategy in modifying prostate cancer-related phenotypes, with a particular focus on pathways related to androgen receptor signalling.
• Recent advances and current status of gene therapy for epilepsy. This review summarises the relevant research and clinical advances in gene therapy, including CRISPR-Cas9, for epilepsy and outlines the challenges facing its clinical application.
• CRISPR-Cas technology in forensic investigations: principles, applications, and ethical considerations. This review provides an overview of potential applications of CRISPR-Cas-based methodologies in several areas of forensic sciences and discusses the legal implications that challenge their routine implementation in this research field.
• Next-generation CRISPR/Cas-based ultrasensitive diagnostic tools: current progress and prospects. This review compiles the experimental evidence consolidating the application of CRISPR/Cas as next-generation biosensors for diagnostic applications.

Opinion and Views

• With five questions, Nature Biotechnology portrays Weixin Tang, a chemist at the University of Chicago and a pioneer in the discovery and engineering of CRISPR-derived gene-editing agents for medical adaptation.
• A perspective in the CRISPR Journal argues that lowering the cost of CRISPR therapies, such as Casgevy, is an urgent ethical necessity. It highlights the inequity posed by the $2.2 million price tag and explores potential solutions to make these groundbreaking treatments accessible to more patients.