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.
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.