science

It's not really an investment thing from my POV. Sure, throwing money at it will speed up research a bit, but there are a huge number of challenges that need to be overcome first, the biggest of these would probably be tissue perfusion - cells tend to die due to lack of nutrients and oxygen. Way too many issues with printing right now. Xenografts are a safer and quicker bet right now because you need to consider immunogenics anyway - if you can't make pig hearts work, you likely won't get patient-specific implants to work either. It's not quite as easy as just 3D-Printing patient stem cells.