Organ transplants can save lives, but they’re plagued by long waiting lists and high chances of rejection. In a major step towards creating new organs on demand, Stanford scientists have now received a contract and funding for experiments to 3D print human hearts and implant them into live pigs.
When a patient’s organs begin to fail, often the only option left is a transplant. And while that can be life-saving, it’s not an easy answer – donated organs are in short supply, meaning many patients die on waiting lists. Even if a match is found, a recipient’s immune system will recognize the organ’s cells as foreign and attack them, leading to rejection. Immune suppressants can prevent this, but that leaves patients vulnerable to other illnesses.
The ideal solution would be to take stem cells from a patient and use them to 3D print a brand new organ. Not only could that be done whenever it’s needed, but because they’re made of the recipient’s own cells, organ rejection would become a thing of the past. The technology required for this scenario has been advancing steadily in recent years, including the ability to print blood vessels into these tissues.
Now, a major step has been made towards this potential future. A team of scientists at Stanford has been awarded a US federal contract worth US$26.3 million from the Advanced Research Projects Agency for Health (ARPA-H), with the goal of bioprinting functional human hearts and implanting them into live pigs, to test the viability of such a procedure.
“It’s truly a moonshot effort, but the raw ingredients for bioprinting a complete and complex human organ are now in place for this big push,” said Mark Skylar-Scott, principal investigator of the project. “With vasculature comes the ability to make large and thick tissues that can be implanted and survive. Thus begins the era of organ biofabrication.”
The team plans to use an automated bank of bioreactors to grow all the cell types needed to produce a human heart, including ventricular and atrial cardiomyocytes, which are responsible for the contraction of the heart while it beats; nodal cells that produce electrical signals and act as natural pace-makers; cells that form the Purkinje fibers, which conduct those electrical signals; smooth muscle cells; immune cells called macrophages; and the endothelial cells that line the blood vessels. These cell cocktails could then be fed into a bioprinter to act as the "ink" to 3D print fully functioning human hearts.
The team says these bioreactors will be able to produce these various cells by the billions, enough to print a heart every two weeks. These hearts will be run through the gauntlet in the lab to improve them and get them ready for eventual tests in live pigs, where they will hopefully be able to keep the animals alive.
“We will use these vast numbers of cells to practice, practice, practice and learn all the design rules of the heart and optimize viability and function at the whole-heart scale for eventual implantation into a pig,” said Skylar-Scott.
While the team hopes that the pig experiments will be possible within the next five years, eventual human trials are likely still many years beyond that. But these tests are a necessary proof-of-concept study on the road to bioprinting new organs from our own cells.
Source: Stanford University
