CRISPR-Mediated Integration of Large Gene Cassettes Using AAV Donor Vectors

Publication date: 18 July 2017
Source:Cell Reports, Volume 20, Issue 3
Author(s): Rasmus O. Bak, Matthew H. Porteus
The CRISPR/Cas9 system has recently been shown to facilitate high levels of precise genome editing using adeno-associated viral (AAV) vectors to serve as donor template DNA during homologous recombination (HR). However, the maximum AAV packaging capacity of ∼4.5 kb limits the donor size. Here, we overcome this constraint by showing that two co-transduced AAV vectors can serve as donors during consecutive HR events for the integration of large transgenes. Importantly, the method involves a single-step procedure applicable to primary cells with relevance to therapeutic genome editing. We use the methodology in primary human T cells and CD34⁺ hematopoietic stem and progenitor cells to site-specifically integrate an expression cassette that, as a single donor vector, would otherwise amount to a total of 6.5 kb. This approach now provides an efficient way to integrate large transgene cassettes into the genomes of primary human cells using HR-mediated genome editing with AAV vectors.

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Teaser

Integration of transgenes into specific sites of the genome of primary cells using CRISPR/Cas9 and AAV donor vectors is currently hampered by the limited packaging capacity of AAV. Bak and Porteus now report a method for efficient integration of large transgenes that exceed the capacity of a single AAV.


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