Cancer tissue isn’t pretty to look at. You’d look like a 25yo clicker from TLOU. Provided those cells can maintain some of their original functions, unlike cancer where the goal is to just keep growing regardless of order.The key would be keeping telomeres from shortening.
Cancer cells preserve telomere length via telomerase, which makes the cells ageless (can reproduce indefinitely).
You'd need to find a way to increase the production of telomerase throughout every dividing cell.
At that point, humans could in appearance look like they're around 25 at all times, but their body will still get clogged up with garbage (heart disease etc) and can acquire cancer and other genetic diseases. So it's more like "agelessness" in quotes.
Still interesting to think about.
I’m kidding, but it’s really difficult to imagine what would happen applying this to all the cells of a living being. Cell cultures can be basically immortal, but those aren’t expected to form actual complex organisms.
And we don’t even really know why people die of old age. When you just lie down and some time later, you’re dead.