[csr86]

Retina is a good example of this. Zebrafish can regrow damaged retina, but while mammals have the same stem cells (Muller glia), they dont repair the retina, but form scar tissue. There is a lot of research and I think they have managed to modify rat genome, so that their retina has showns some repair abilities. The problem is that it often causes tumors.

I have other retina permanently damaged, and suffer from double vision when looking small objects like text.

[cortesoft]

Ah, I was wondering the evolutionary reason why those genes would have gone dormant.

Cancer is a sensible answer.

[Sharlin]

Yep, the unfortunate flipside of "let's use stem cells to rebuild stuff" is always "let's use stem cells to give us cancer". Technology might help alleviate the cancer part compared to blind evolution, hopefully.

[api]

Some aging mechanisms like telomeres are also mechanisms to prevent cancer by limiting cell division.

It looks like one of the optimization edges walked by evolution is a conflict between longevity and the ability to repair and regenerate versus not getting cancer.

It’s easy to make human cell lines immortal, but that will kill you.

One route I can imagine to radical life extension is to start by editing the genome to introduce much more robust but different anti cancer adaptations. Then start turning regenerative stuff and things like telomerase back on.

[wafflemaker]

I've learned about the cancer vs tissue repairability (or cancer vs heart/cardiovascular failure) from Joe Rogan's podcast with Bret Weinstein (or his brother, don't remember).

It's visible in death causes - pretty much all non accident deaths are divided between cancer and heart attack.

A very interesting thing discussed in that podcast was about transgenic (or maybe all?) lab mice bred in USA. These mice are used for initial screening for nearly all drugs. And due to some error and ignorance, unbeknownst to most people using the mice, nearly all mice are predominantly on one side. (Sorry, don't remember which). They just all come from the same family.

Which means that nearly all drugs in the past few decades are skewed toward either giving people cancer or heart attacks.

This is due to mice being extra resistant to one of these and therefore not properly signaling when the drug is likely to give people heart attacks or cancer.

Sorry, don't remember which it is exactly.

[themafia]

Teratomas are insane.

https://en.wikipedia.org/wiki/Teratoma