Almost always, building something is harder than tearing it down. Similarly, knocking in genes poses a greater challenge than knocking them out. It’s a reality that researchers will have to overcome in order to get the most out of gene editing.
In the past few years, researchers have developed many new strategies to boost the efficiency of knocking in genes both large and small using CRISPR-Cas9, and along the way they’ve proposed and tested new applications for this type of gene editing. Here, The Scientist explores a few of the most promising approaches.
Researcher: Channabasavaiah Gurumurthy, director of the mouse genome engineering core facility, University of Nebraska Medical Center
Project: A few years ago, musing over the difficulty of knocking in genes while trying to do so into mouse zygotes, Gurumurthy and his colleagues had a revelation.
Researchers were successfully inserting short, single-stranded DNA, so why not try making a knock-in by inserting long, single-stranded DNA? Indeed, the approach, which Gurumurthy calls Easi-CRISPR (efficient additions with ssDNA inserts -CRISPR), boosts efficiency by 2.5 times, and using single-stranded DNA slashes the rate of off-target insertions 100-fold in cell culture.
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