A decellularized organ is one that has had the cells stripped out, such as via detergent solutions, leaving behind the extracellular matrix. Decellularization is a way to obtain a fully detailed organ scaffold, complete with chemical cues to guide the reconstruction of tissues when new cells are added, without having to build it from scratch. That task that is presently impossible, though some groups are making headway in the construction of scaffolds detailed enough for use in tissue engineering. Interestingly, decellularization allows the use of human cells in animal organs: this may be a viable path towards farming pigs for organs that can be recellularized with a patient’s own cells and then transplanted without risk of rejection, for example. It remains to be see as to whether this approach stays far enough ahead of efforts to build organs from scratch to have commercial viability.
Using skin cells from human volunteers, researchers have created fully functional mini livers, which they then transplanted into rats. In this proof-of-concept experiment, the lab-made organs survived for four days inside their animal hosts. These mini livers secrete bile acids and urea, just like a normal liver, except they’re made-to-order in the lab using patient cells. And, although liver maturation takes up to two years in a natural environment, the researchers did it in under a month.
As an ultimate test, the researchers transplanted their lab-grown mini livers into five rats, who were bred to resist organ rejection. Four days after the transplant, researchers investigated how well the implanted organs were faring. In all cases, blood flow problems had developed within and around the graft, but the transplanted mini livers worked – the rats had human liver proteins in their blood serum.
Researchers are optimistic that this research is not merely a stepping-stone on the path toward growing replacement organs in a lab, but also a useful tool in its own right. “The long-term goal is to create organs that can replace organ donation, but in the near future, I see this as a bridge to transplant. For instance, in acute liver failure, you might just need hepatic boost for a while instead of a whole new liver.”