GenScript Launches Single-Stranded DNA Service for CRISPR-based Gene Editing

GenScript^®, at the American Association for Cancer Research, has launched a single-stranded DNA (ssDNA) service. The new service offers researchers access to high quality, pure ssDNA for CRISPR-based gene insertion, ultimately helping to accelerate the development of gene therapy, cell therapy, as well as transgenic animal models for cancer research and treatment. GenScript utilizes a patent-pending enzymatic approach to develop high purity DNA oligos up to 3000 nucleotides long in large quantities, with an undetectable level of double-stranded DNA (dsDNA) contamination and minimal DNA base damage.

One of the DNA repair mechanisms triggered by CRISPR/Cas9 is the homology directed repair (HDR) process, in which DNA templates can be inserted into double-stranded breaks created by Cas9 via homologous recombination. Traditionally, dsDNA has been used as HDR donor templates. However, recent studies have demonstrated that using ssDNA as a CRISPR HDR-based gene insertion template is more precise and efficient, producing fewer off-target integrations compared with dsDNA.

“Gene engineering techniques can be used to generate more potent T cells for cancer immunotherapy. Because ssDNA when used with Crispr/Cas9 appears to reduce the frequency of off target insertions when compared to dsDNA, we are exploring the use of ssDNA to genetically modify T cells," added Eric Tran Ph.D., leader of the Antitumor T-Cell Response Laboratory at the Earle A. Chiles Research Institute, a division of the Providence Cancer Institute. "The ability to insert genes at precise locations in the genome holds great promise for the generation of safer and more effective T cells.”

A recent study published by Roth et al. in Nature, demonstrated that ssDNA HDR templates can be used to insert large genes at specific genetic sites in primary T cells without using viral vectors. Non-viral ssDNA templates were shown to have similar knock-in efficiency, but significantly reduced off-target integration (by over 20 fold), compared with dsDNAs in T-cell engineering and cancer research.

"Long ssDNA sequences are difficult to produce in the lab, especially at the high concentrations necessary for gene editing experiments," said Theodore Roth from the UCSF Marson Laboratory and first author of the study. "We were able to successfully integrate large DNA sequences into primary human T cells using GenScript's long ssDNA product."

GenScript’s ssDNA service provides high purity ssDNA up to 3000 nucleotides long at flexible quantities. A unique quality control process involves an additional sequence verification step of the final ssDNA product, ensuring 100 percent sequence accuracy.

“This newly launched ssDNA service, along with GenScript's existing CRISPR plasmids, synthetic sgRNAs, Cas9 proteins, and CRISPR cell line services, aims to make genome editing accessible and easy for all research purposes,” said Cedric Wu, Ph.D., GenScript Sr. Director of R&D. "GenScript remains committed to expanding our offerings with innovative and high quality services, such as our ultra-pure and sequenced verified ssDNA products, that accelerate research and ultimately make humankind and the environment healthier."

GenScript is exhibiting at AACR Booth #5116.

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