Fighting the disability of old age
Regenerative medical therapies are ones that rebuild or repair the body, rather than trying to ‘reset’ its control systems (like drugs) or get rid of diseased bits (like surgery). Regenerative medicine covers a wide range of technologies - look at Wikipedia for a full survey. My current interest is in the damage accumulates in the body with age (See 'Chemical Errors' on the left), why the body does not repair that, and how we can boost our own ability to rejuvenate ourselves (or at least, slow down the growing tide of failing tissues and organs that makes being old less enjoyable than it might be.) This mode of regenerative medicine ranges from re-starting hair growth to regrowing limbs.
Why do this? In part, because the disability of old age is the number one economic problem facing Western societies today (the pension crisis is only part of this). In part (and let's be honest here) because there is a huge amount of money to be made out of healthcare treatments that actually treat the problems of old age, rather than just patch up the symptoms. And in part because I, personally, want to be alive when the first spacecraft to Proxima b sends its results back home.
But the main reason is that I have seen relatives decline from being fascinating, active friends to incapable dependents who would rather not be alive, and I do not want that to happen to anyone else. This is not just "Nowadays I need the little bllue pill..." This is the pointless destruction of a human being. UK commedians Mitchell and Webb caught the tragedy of this brilliantly in this very funny but devastating sketch. Ageing does not have to be a decline into degrading, painfull helplessness. We can 'age gracefully' if we have the physical and mental ability to do so. This is the promise that regenerative medicine holds out.