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

Proprietary enzymatic synthesis technology produces high quality sequences up to 3000 nucleotides long

PISCATAWAY, N.J. and ATLANTA, April 1, 2019 /PRNewswire/ -- GenScript®, the world's leading gene synthesis provider, today at the American Association for Cancer Research 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.

(PRNewsfoto/GenScript Biotech Corporation)

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," said 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."

More information about GenScript's ssDNA service may be found here, as well as in a case study and a webinar hosted by Theodore Roth. GenScript is exhibiting at AACR Booth #5116.

About GenScript
GenScript is a leading contract research organization providing gene, peptide, protein, CRISPR, and antibody reagents to scientists in over 100 countries worldwide. Since its foundation in 2002, GenScript has grown exponentially through partnerships with scientists conducting fundamental life science and translational biomedical research, as well as early stage pharmaceutical development. With a mission to improve the health of mankind and nature through biotechnology, the company has developed the best-in-class capacity and capability for producing biological reagents in order to Make Research Easy for all scientists. For more information, visit

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