Base editing of RDEB fibroblasts

Testing the efficacy of genomic base editing in dystrophic epidermolysis bullosa primary fibroblasts

Lay summary

All forms of dystrophic epidermolysis bullosa (DEB) result from faults (mutations) in the Collagen VII gene (COL7A1). These mutations alter the Collagen VII in the skin which normally makes adhesion structures called anchoring fibrils that hold the outer layer (epidermis) and inner layer (dermis) together to prevent blistering. Previous research studies and clinical trials have attempted to fix the COL7A1 mutations by replacing the entire COL7A1 gene, but this form of gene therapy has had limited clinical benefits.

This research looks at a different approach to gene therapy, developing a technique called “gene editing”. This method allows us to try to correct the COL7A1 mutations in a more focused manner, somewhat like fixing typos in a word document by cutting and pasting correct text directly over the error. Our research work therefore looks to develop gene editing for COL7A1 mutations as future new therapies for DEB.

This research will test the efficacy of this gene editing technique and assess the safety and efficacy of using this technique in clinical practice. This grant was towards consumables costs.

Scientific Summary

Most pathogenic COL7A1 mutations in dystrophic epidermolysis bullosa (DEB) involve single nucleotide substitutions, with C>T changes often underlying cases of recessive DEB (RDEB), e.g. in loss-of-function nonsense mutations such as CGA to TGA. As a strategy to correct such mutations, adenine base editors (ABE) represent a type of genome editing system that mediates targeted editing of C>T without creating DNA double-strand breaks or requiring an exogenous DNA repair template, thereby increasing the editing efficiency and minimizing the off-target risks.

The objective of this project is to correct pathogenic COL7A1 C>T mutations in primary fibroblasts from individuals with RDEB and show type VII collagen (C7) protein restoration in the gene corrected fibroblasts.

The project will also assess safety and efficacy issues relevant to clinical application by incorporating reagents that can subsequently be adapted to clinical practice.

In essence, this project will establish a foundation to test new base editing technology for clinical translation for DEB patients in the near future.