This popular science article looks at efforts in one laboratory to develop a supply of decellularized animal kidneys for transplantation into human recipients. At the present time decellularization appears to be the most practical way to make xenotransplantation viable: replacing the animal cells with human cells removes most of the issues of transplant rejection. Xenotransplantation would be a transitional source of organs, bridging the gap between today and a future in which organs are grown directly from a patient's own cells when required, or in which the need for organ transplants is eliminated by methods of manipulating cell behavior to spur regrowth and regeneration in situ:
In the ground-floor labyrinth that connects UF Health Shands Hospital to the UF health sciences campus, a handful of scientists are super excited about research that one day could mean the end of long waiting lines for kidney transplant patients. The promise lies in a soft sponge-like structure that is about the size of a bar of soap and is considered a "scaffold" for building healthy human kidneys. The soap-sized structure is a baby pig's kidney, drained of its blood and cells. Over the course of three days, chemicals strip the kidney of swine cells so it can be injected with human stem cells.
Scientists also have successfully grown human stem cells with other, "easier" organs such as the bladder and trachea. "The kidney is one of the most difficult because of the complexity of the organ." The scaffold is not, however, just an inert skeleton. It contains proteins with chemical signals that guide human stem cells once they are implanted, or "seeded," inside the scaffold. The kidney contains 30 different cell types, so the stem cells can differentiate into these types once inside the scaffold.
The scaffold also is continuously pumped with nutrients such as oxygen, sugars and proteins to help the stem cells develop into a newly formed kidney. The scaffold gradually begins to redden as it morphs into an adult kidney. "It's still very new and very exciting."