Decoding the complexity of on-target integration: characterizing DNA insertions at the CRISPR-Cas9 targeted locus
Juan-Juan Zhao1,2, Xin-Yu Sun1,2, Sai-Ning Tian3
1State Key Laboratory of Experimental Hematology, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, National Clinical Research Center for Blood Diseases, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, 300020, China.
BMC Genomics
|February 17, 2024
Summary
This study developed a new method to analyze complex CRISPR-Cas9 gene insertions for in vivo gene therapy. The technique accurately characterizes large DNA insertions and potential off-target integrations, improving gene editing safety.
Area of Science:
- Molecular Biology
- Gene Therapy
- Genomics
Background:
- CRISPR-Cas9 gene editing shows promise for in vivo gene therapy, exemplified by successful hemophilia A treatment in mice via F8 gene insertion.
- Ensuring the safety and specificity of CRISPR-Cas9 in vivo applications requires robust methods for analyzing on-target editing outcomes.
- Current methods may not fully capture the complexity of large insertions and potential unintended integrations at edited loci.
Purpose of the Study:
- To introduce and validate a novel methodology for analyzing complex insertion sequences at CRISPR-Cas9 edited loci.
- To assess the safety and specificity of in vivo gene therapy by characterizing on-target editing outcomes, including large insertions.
- To provide a new tool for quality control in gene editing research and therapeutic development.
Main Methods:
- Utilized barcoded long-range PCR for analyzing complex insertion sequences.
- Employed CRISPR RNP-mediated deletion to isolate unedited alleles.
- Incorporated magnetic bead-based long amplicon enrichment and nanopore sequencing for detailed characterization.
Main Results:
- Identified expected F8 insertions and various fragment combinations from linearized plasmid donors.
- Documented insertions exceeding 10 kbp, representing the first such observation in this context.
- Detected a small proportion of insertions originating from non-donor sources, including Cas9-sgRNA plasmids, genomic DNA, and LINE-1 elements.
Conclusions:
- The developed method provides a robust approach for analyzing complex on-target editing, especially for challenging large in vivo insertions.
- This technique serves as a valuable tool for quality control, enhancing the detailed characterization of edited genomic sequences.
- Findings contribute to improving the safety and effectiveness of CRISPR-Cas9 gene therapy for disorders like hemophilia A.
