Can CRISPR-Cas9 make changes on a living organism? What's the limit here? E.g. reversing/restoring hearing loss in a living adult mice.
$\begingroup$ Hearing loss is a particularly tricky phenotype to mention, because a) hearing loss has many many, sometimes unrelated, causes, and b) because hearing loss is often associated with death of cells that do not reproduce in adults. $\endgroup$– Bryan Krause ♦Jun 1, 2018 at 17:48
Answer is yes, but it depends on which kind of phenotype you're going to restore/change. As you can imagine, using crispr cas9 on an high amount of cells require one condition: edited cells need to have a clear advantage in surviving besides the previous.
Here's an example of a crispr-cas9 protocol followed to restore a wildtype phenotype in adult mice.