Scientists have successfully grown human stem cells in pig embryos making it possible, in the future, to develop human organs in animals for transplant. Stem cells from patient’s skin would be used to grow the desired organ in an animal and later harvested and transplanted into the patient’s body. Chimeras, animals composed of two genomes would be used for implanting human stem cells. Use of patient’s own cells would reduce the risk of immune rejection. Many technical and ethical barriers remain to be overcome.
To achieve this goal, researchers need to engineer pigs that cannot make the organ of interest, thus allowing the human stem cells to construct that organ. The pig will supply only blood vessels and nerves which will make it easier to be replaced by the recipient’s cells upon transplant. If the immune system does reject the organ, researchers will have to come up a way to humanize pig’s vasculature genes to be transplanted with the organ.
This recent success is a small step in a process that will take several years to develop. Regarding ethical concerns surrounding chimera, scientists are certain that it could be addressed.
Nicholas Wade, New Prospects for Growing Human Replacement Organs in Animals, N.Y. Times ( Jan. 26, 2017), https://www.nytimes.com/2017/01/26/science/chimera-stemcells-organs.html