Decellularization is the process of taking donor tissue, such as a complete organ, stripping out its cells to leave the extracellular matrix structure, and then repopulating that structure with another individual's cells to reform a functional organ. This produces donor tissue that will not be rejected by a transplant recipient, and has been successfully used in a few human transplants of less complicated tissue structures such as the trachea.
This technology is an important stepping stone on the way towards organs created from scratch; it works around the present inability to build a sufficiently detailed and functional framework for complex tissue. The extracellular matrix from existing tissue provides chemical cues and other necessary items that allow cells to correctly form the many intricate structures, such as blood vessel networks, needed for a fully functional organ.
In the laboratory, a number of complete animal organs have been successfully decellularized and transplanted - and kidneys are now included in that list, albeit only partially functional kidneys, a starting point for better results in years ahead:
[Researchers have] engineered functional rat kidneys by stripping donor kidneys of their cells and then repopulating the remaining collagen substructures with new cells. The bioengineered kidneys produced urine in laboratory dishes and when implanted in living animals. The advance could be good news for the 100,000 Americans waiting for donor kidneys for transplant, because it suggests that someday scientists might be able to grow custom-made kidneys for people, using a patient's own cells to seed tissues.
The process at the center of his team's approach is called "decellularization." In a carefully calibrated process, researchers removed a kidney from a cadaver and then introduced a series of washing agents into its vascular system to remove the organ's cells. [Then] they introduced immature cells that could form kidney tissues and blood vessels into the acellular scaffold.
After a short time, the new kidneys could produce urine. They didn't work as well as normal, healthy kidneys would - in the laboratory dish, they cleared creatinine (a blood component filtered by the kidneys) 23% as well as a native kidney; once implanted in animals, about 5% to 10% as well. But "the bottom line is, we saw urine production."