How about this - here's a company that's developing an artificial wearable kidney. That's good, in fact that's great! It is a big step forwad, especially if more studies prove its efficacy and the problems aree fixed (there's only been one so far, funded by the company itself - some positive results, but also problems with the device, AFAIK).
Now how about developing an artificial implantable kidney? Especially one that doesn't need replacement more than once a decade or so, or even better, at all. I would be all over that project, really :) That's the real X-prize of organ replacement, IMO.