What if doctors could just print a kidney, using cells from the patient, instead of having to find a donor match and hope the patient’s body doesn’t reject the transplanted kidney?
The soonest that could happen is in a decade, thanks to 3D organ bioprinting, said Jennifer Lewis, a professor at Harvard University’s Wyss Institute for Biologically Inspired Engineering. Organ bioprinting is the use of 3D-printing technologies to assemble multiple cell types, growth factors and biomaterials in a layer-by-layer fashion to produce bioartificial organs that ideally imitate their natural counterparts.
This type of regenerative medicine is in the development stage, and the driving force behind this innovation is real human need. In the United States, there are 106,800 men, women and children on the national organ transplant waiting list as of March 8, 2023, according to the Health Resources & Services Administration. However, living donors provide only around 6,000 organs per year on average, and there are about 8,000 deceased donors annually who each provide 3.5 organs on average.
To begin the process of bioprinting an organ, doctors typically start with a patient’s own cells. They take a small needle biopsy of an organ or do a minimally invasive surgical procedure that removes a small piece of tissue, “less than half the size of a postage stamp,” Dr. Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine said. “By taking this small piece of tissue, we are able to tease cells apart and we grow and expand the cells outside the body.”
This growth happens inside a sterile incubator or bioreactor, a pressurized stainless steel vessel that helps the cells stay fed with nutrients – called “media” – the doctors feed them every 24 hours, since cells have their own metabolism. Each cell type has a different media, and the incubator or bioreactor acts as an oven-like device mimicking the internal temperature and oxygenation of the human body.
“Then we mix it with this gel, which is like glue,” Atala said. “Every organ in your body has the cells and the glue that holds it together. This glue is Atala’s nickname for bioink, doctors load each bioink – depending on how many cell types they’re wanting to print – into a printing chamber, using a printhead and nozzle to extrude an ink and build the material up layer by layer. Creating tissue with personalized properties is enabled by printers being programmed with a patient’s imaging data from X-rays or scans.
“With a color printer you have several different cartridges, and each cartridge is printing a different color, and you come up with your final color,” Atala added. Bioprinting is the same; you’re just using cells instead of traditional inks. The printing process typically lasts several hours. The time from the biopsy to the implantation is about 4-6 weeks.
The ultimate challenge is “getting the organs to actually function as they should,” so accomplishing that “is the holy grail,” said Lewis. “Just like if you were to harvest an organ from a donor, you have to immediately get that organ into a bioreactor and start perfusing it or the cells die,” she added. To perfuse an organ is to supply it with fluid, usually blood or a blood substitute, by circulating it through blood vessels or other channels.
Depending on the organ’s complexity, there is sometimes a need to mature the tissue further in a bioreactor, Lewis said. “There’s just a number of plumbing issues and challenges that have to be done in order to make that printed organ actually function like a human organ would in the body. And honestly, this has not been fully solved yet.”
Atala and Lewis are conservative in their estimates about the number of years remaining before fully functioning bioprinted organs can be implanted into humans.
“The field’s moving fast, I think we’re talking about a decade plus, even with all of the tremendous progress that’s been made,” Lewis said. “I learned long ago never to predict because you’ll always be wrong,” Atala said. “There’s so many factors in terms of manufacturing and the US Food and Drug Administration regulation. At the end of the day, our interest, of course, is to make sure the technologies are safe for the patient above all.”
Whenever bioprinting organs becomes an available option, affordability for patients and their caregivers shouldn’t be an issue. They’ll be “accessible for sure,” Atala said. “The costs associated with organ failures are very high. Just to keep one patient on dialysis is over a quarter of a million dollars per year. So, it’s a lot cheaper to create an organ that you can implant into the patient”.
The average kidney transplant cost was $442,500 in 2020, according to research published by the American Society of Nephrology, by the way.
Kristen Rogers, CNN, 3/10/2023