The regrowing limb thing is a nonstarter due to the issue of time if I understand correctly. Salamanders that can regrow limbs take roughly the same amount of time to regrow them as the limb takes to grow in the first place. So it would be 1-2 decades before the limb was of adult size.
Secondly it’s not as simple as just smearing on some stem cells to an arm stump. Limbs form because of specific signalling molecules in specific gradients. I don’t think these are present in an adult body once the limb is made. So you’d need a socket which produces those which you’d have to build in the lab, attach to blood supply to feed the limb, etc.
For a good few years you’d have a tiny baby limb, which would make it impossible to have a normal prosthetic. I also think most people just don’t want a tiny baby limb attached to them. I don’t think growing it in the lab for a decade is feasible for a variety of reasons. I also don’t know how they planned to wire the nervous system in, or ensure the bone sockets attach properly, or connect the right blood vessels. The challenge is just immense and it gets less and less worth over time it as trauma surgery and prosthetics improve.
The regrowing limb thing is a nonstarter due to the issue of time if I understand correctly. Salamanders that can regrow limbs take roughly the same amount of time to regrow them as the limb takes to grow in the first place. So it would be 1-2 decades before the limb was of adult size. Secondly it’s not as simple as just smearing on some stem cells to an arm stump. Limbs form because of specific signalling molecules in specific gradients. I don’t think these are present in an adult body once the limb is made. So you’d need a socket which produces those which you’d have to build in the lab, attach to blood supply to feed the limb, etc.
The first issue seems minor—even if true, a 40 year old man could have a new arm by 60
For a good few years you’d have a tiny baby limb, which would make it impossible to have a normal prosthetic. I also think most people just don’t want a tiny baby limb attached to them. I don’t think growing it in the lab for a decade is feasible for a variety of reasons. I also don’t know how they planned to wire the nervous system in, or ensure the bone sockets attach properly, or connect the right blood vessels. The challenge is just immense and it gets less and less worth over time it as trauma surgery and prosthetics improve.