In experiments aimed at finding new ways to grow human organs inside animals, researchers have for the first time created chimeric embryos containing human and porcine stem cells.
A team of researchers succeeded in creating mixed embryos that contained both human cells and porcine cells with the aim of developing human organs by animals, which could then be recovered and transplanted into sick people. These chimeric embryos (which contained only a small amount of human cells) managed to develop for several weeks (four, the maximum allowed by regulations) in female pigs before the pregnancies were terminated according to the study published in the journal Cell.
» This is an important first step “Said Juan Carlos Izpisua Belmonte, professor at the Salk Institute for Biological Studies in La Jolla, California, main author of this work explained in a press release. » The ultimate goal is to cultivate human tissues or organs (pancreas, liver, heart, etc.) in animals such as sows that can be transplanted without rejection, but we are still a long way from that. »
A chimera is a single organism that consists of cells from two or more beings: two sets of DNA with the code to make two separate organisms. In the present case, the embryos contained mostly animal cells with a relatively low number of human cells. To create the embryos, the researchers injected human stem cells into animal embryos at a very early stage of development on the fifth or sixth day.
For this experiment, the scientists have used human cells called induced pluripotent stem cells. Those are from « adult » cells that have been reprogrammed to become cells at the stage of early development. Thus, they have the potential to form any tissue in the body.
For Bruce Whitelaw, professor of animal biotechnology at the University of Edinburgh in the United Kingdom, this work is » exciting « , because » they pave the way for important advances in this area, although the subject is quite controversial, especially for ethical issues.