A research team funded by the National Institutes of Health (NIH) has developed an improved CRISPR gene-editing system using a naturally small enzyme, Al3Cas12f, that can be effectively delivered into human cells. This breakthrough addresses a key obstacle in gene therapy by enabling targeted delivery inside the body, which could broaden clinical applications for diseases including cancer and amyotrophic lateral sclerosis (ALS).
Common gene-editing proteins like Cas9 are often too large to fit into adeno-associated virus (AAV) vectors, a preferred method for in vivo delivery of gene therapies. The researchers identified Al3Cas12f as a compact enzyme naturally suitable for packaging into these vectors. Using advanced imaging and machine learning analysis at the University of Texas at Austin, they discovered that Al3Cas12f forms a more stable and tightly connected complex compared to similar small enzymes, facilitating more effective editing in human cells.
The team engineered an enhanced variant named Al3Cas12f RKK, which dramatically increased gene-editing efficiency from less than 10% to over 80% across multiple tested genomic targets, with efficiency reaching as high as 90% in one commonly edited region. This improvement suggests the enzyme’s potential for precise and robust gene modifications.
Testing included introducing the engineered enzyme’s instructions directly into a human cell line derived from a leukemia patient. The targeted genes are implicated in several conditions such as cancer, atherosclerosis, and ALS, indicating potential therapeutic relevance.
The next step for the researchers is to evaluate the performance of Al3Cas12f RKK when packaged within AAV vectors, aiming to verify its suitability for targeted delivery in living organisms. Success in these tests could accelerate the development of gene-editing therapies for a wider range of diseases.
Why it matters
This advance could overcome a major limitation in current CRISPR-based treatments by enabling efficient, precise gene editing directly inside the body, expanding therapeutic options beyond cell types that can be modified ex vivo, such as blood and bone marrow cells. It marks progress toward safer, more accessible gene therapies for complex diseases.
Background
The NIH’s National Institute of General Medical Sciences (NIGMS) supported this research under grant R35GM138348. NIGMS focuses on foundational biological research to inform disease diagnosis and treatment development. CRISPR technology has revolutionized gene editing but has been hindered in clinical applications by challenges in delivering large editing proteins. The discovery and engineering of compact enzymes like Al3Cas12f promise to address these technical barriers.
For more information about NIGMS and NIH research programs, visit https://www.nigms.nih.gov and https://www.nih.gov.
Sources
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