In an effort to ensure a steady supply of compatible organs, a team of scientists from Massachusetts General Hospital (MGH) is working on ways to create bioengineered human hearts by first stripping donor hearts of cells that could provoke an immune response in a potential recipient, and then using the recipient's own induced pluripotent stem cells (iPSCs) to generate cardiac muscle cells that can be used to repopulate the heart in an automated bioreactor system.

Every year, 800,000 people worldwide have heart conditions that require a transplant. Unfortunately, there are only enough suitable donor hearts for around 3,500 operations. Part of the reason for this isn't that there aren't enough healthy hearts donated to go around, but that a heart needs to be biologically compatible with the recipient.

And even if there is an extremely close tissue match, the recipient's body will treat still the new heart as alien and attack it. To prevent this tissue rejection, the recipient's autoimmune system must be suppressed by a battery of pills for a lifetime, combined with another battery of pills to correct the damage caused by suppressing the immune system.