Decellularization involves taking a donor organ and stripping its cells, leaving just the shaped extracellular matrix behind. When new cells of the right types are seeded into the matrix, they will inhabit it, grow, and follow its cues to rebuild the tissue as it was. This might prove to be a shortcut to the future of organs grown to order - you can't use it to produce an organ such as the heart from scratch, but you can take animal organs and make it possible to transplant them into humans with minimal risk of rejection.
This, at least, is the goal. So far decellularization has worked for some human donor tissues, such as veins, replacing the donor's cells with those of the recipient to remove immune rejection issues. This suggests that it will work just fine for animal organs too. Researchers are working on opening the doors to widespread xenotransplantation of pig organs, for example, by turning porcine tissues into those of the organ recipient.
One recent morning, a pig heart hung suspended in a clear homemade tank in the lab built for Taylor and her team. Filled with detergent, the heart had expanded to the size of a large man's fist, excess liquid dripping slowly out its sides.
Once the heart is thoroughly cleaned, hard-working human stem cells - immature cells found in our organs and tissues that help repair damage on a daily basis - will bring it to life. "We can take stems cells from bone marrow, blood or fat and place them onto a heart, liver or lung scaffold," Taylor explains. "My motto for a long time has been 'Give nature the tools and get out of the way.' "
Taylor and her team will add stem cells to the heart one of two ways: by inserting a tube in the aorta and letting the cells drip inside, or by injecting the cells with a syringe through the wall of the heart. A heartbeat is perceptible after just a few days. Within a few weeks, the heart is strong enough to pump blood.
Taylor predicts that in the next two years, she and her team will approach the U.S. Food and Drug Administration and ask to do a first-in-human study with the bio-artificial hearts. "Will it be a whole heart? Probably not," Taylor says. "But it could be a cardiac patch or a valve. We might start with a piece to show the safety and efficacy of the technology."