ToolGen Highlights Study Results Demonstrating Utility Of AAV-Compatible Cas9 System In Vivo Genome Editing

Findings published today in peer-reviewed journal, Nature Communications

South Korea, Asia February 22, 2017 - ToolGen, Inc. (KONEX, 199800), a biotechnology company specializing in genome editing, today announced encouraging data from a study evaluating Campylobacter jejuni Cas9 (CjCas9), the smallest Cas9 orthologue characterized to date, for efficient genome editing in vivo.

Results from the study entitled “In vivo genome editing with a small Cas9 orthologue derived from Campylobacter jejuni,” were published online in the peer-reviewed journal Nature Communications. The study was led by researchers from ToolGen, Dr. Jin-soo Kim, Principal Investigator, from the Institute for Basic Science) and Dr. Jeong Hun Kim from Seoul National University Hospital.

The study demonstrated the ability to package the CjCas9 gene, its sgRNA sequence into a single Adeno-associated virus (AAV) vector for in vivo gene surgery. Furthermore, CjCas9 was shown to be highly specific in cleaving the target sites in the human or mouse genome in vitro, which could have significant potential precision genome editing and gene surgery. CjCas9 delivered via AAV, induced target mutations in mouse muscle cells and retinal pigment epithelium cells (RPE) with no off-target mutations detected in the genome. The study confirmed that CjCas9 targeted to the Vegfa or Hif1a gene in RPE cells reduced the size of laser-induced choroidal neovascularization, a condition leading to the formation of new blood vessels in the choroid layer of the eye. This suggests that gene surgery with CjCas9 could be a promising treatment option for age-related macular degeneration, a leading cause of blindness in adults.

Seokjoong Kim, Research Director of ToolGen commented, “Despite the recent advances in CRISPR/Cas9 genome editing technology, it has been difficult to package a whole cassette of Cas9 and sgRNA into certain viral vectors such as AAV owing to the large size of the most commonly used Cas9 genes. The need to split the gene and package it into multiple AAV vectors results in a less than optimal delivery method, and the split gene is less active than its intact counterpart. However, our study, utilizing CjCas9, which is significantly smaller than other commonly used Cas9 genes, enables us to overcome these problems. We are very pleased with the findings obtained from this study and strongly believe that this data can serve as a foundation for further exploration in the CRISPR/Cas9 arena.”

Jeong Hun Kim, Clinical Professor in the Department of Ophthalmology, Seoul National University Hospital commented, “This work shows promising results for the application of CRISPR/Cas9 for eye diseases. We look forward to extending these observations on the successful modulation of neovascularization through targeted in vivo genome editing to additional disease models and large animals that could potentially establish a new class of therapeutic options. Additionally, with an efficient genome editing process established in the eye, we can broaden target indications to include rare diseases.”

For more information, contact Seokjoong Kim, Director of Research Center Tel. +8210-6776-7824,

About ToolGen, Inc.

ToolGen, Inc. is a biotechnology company focused on the development and application of genome editing technologies. It creates, and holds intellectual property rights for essential tools and technologies for editing the genetic information in microbial, plant, animal, and human cells. ToolGen’s mission is to translate the potential of our innovative platform technology into transformative products for biomedicine and agriculture. For more information, please visit

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