CrateDane t1_iy51kwm wrote on November 28, 2022 at 8:21 PM

CRISPR-Cas9 can cut the DNA in cells whether or not they are dividing.

The problem arises if you then try to rely on HDR to insert a sequence at the break. The HDR pathway is inactive in non-dividing cells, so that strategy will not work. But there are other ways to insert DNA in this scenario, for example HITI. And if you are not trying to insert DNA, but just knock out a gene, it will work anyway.

SheScientist t1_iy6dmwb wrote on November 29, 2022 at 2:05 AM

Yes! You can also be hindered by HDR when you want to knock out a gene in dividing cells. This was an unfortunate end to one of my grad school experiments. I knocked out a gene in a system where cells were rapidly dividing, and instead of getting a nice knockout, I got less than 10% editing in vivo because HDR is preferred during cell division when the sister chromatid is nearby. I get better knockout in that system when cells are dividing infrequently.

The answer to the OP’s question is definitely that CRISPR works no matter if cells are dividing, but how well and how permanently it works depends on the system, the type of edit, and a whole host of other factors.