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CRISPR/Cas9-mediated repair of COL7A1

Ongoing
Project leadDr. Ulrich Koller
Organisation EB House Austria
Project budgetEUR 488.250,00
Start date / Duration01. Oct 2014 / 75 months
Funder(s) / Co-Funder(s) DEBRA Austria
Research area Molecular therapy, Cellular therapy

Project details

Short lay summary

The main aspect of this project is the establishment of a designer nuclease-based gene therapy for DEB patients with COL7A1 mutations. Although a gene replacement strategy was successfully applied for JEB patients with LAMB3 deficiency, viral delivery systems are compounded by a random genomic integration of the transgene. Due to safety concerns, a virus-free therapeutic option for genodermatoses should be a research focus. Many gene editing therapeutic approaches employ ex vivo modification, screening and re-transplantation. This enables selection against incorrectly modified cells. Currently, low gene repair efficiencies hinder the application of existing gene editing strategies and the development of translational applications in this field. This project aims to develop an efficient gene editing protocol, later translatable into a clinical setting.

Scientific summary

Currently, we are working on a potentially traceless CRISPR/Cas9-based gene editing strategy to correct a frequent mutation within COL7A1 causing RDEB. Designer nucleases, such as CRISPR/Cas9, represent promising tools for the permanent correction of disease-associated mutations in a site-specific manner. A single treatment is often sufficient to obtain permanent restoration of gene function. Homologous recombination comprises the most traceless approach to gene editing. Therefore, we aim to induce a shift from the frequent error prone end joining pathways to this more elegant repair pathway. This should be possible with the use of Cas9 nickases (Cas9n), proximal targeting of nucleases to the mutation, donor template optimization and cell cycle modulation. Normally the Cas9 from Streptococcus pyogenes is preferentially used to efficiently generate double strand DNA breaks (DSBs). However, double nicking via Cas9 nickases (Cas9n) represents a promising alternative for gene disruption. Electroporation of Cas9 ribonucleoproteins (RNPs) comprises a promising and safe method of delivering gene editing agents into cells, associated with reduced off-target effects, high rates of gene disruption and a reduced window of activity. The co-delivery of the RNPs and a donor template for homologous recombination should result in the correction of the disease-associated mutation. In summary, this study aims to develop a method of highly efficient CRISPR/Cas9-mediated HR with clinical applicability. We intend to perform this in the context of COL7A1-associated dystrophic epidermolysis bullosa (DEB).

Strategic relevance

The primary goal of the project is the development of an HR-based gene editing protocol to achieve a traceless correction of gene function in epidermal stem cells from dystrophic EB patients. Once established the protocol should be fast and easily adaptable for any EB-associated mutation aiming at the generation of a toolbox to treat as many patients as possible.


Keywords

RDEB
CRISPR/Cas9
homologous recombination
ex vivo gene therapy
Koller
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