However, the research remains at a very early stage and proved more difficult than expected, the researchers reported in the peer-reviewed journal Cell.
“This is an important first step,” said lead investigator Juan Carlos Izpisua Belmonte, a professor in the Salk Institute of Biological Studies’ Gene Expression Laboratory.
“The ultimate goal is to grow functional and transplantable tissue or organs, but we are far away from that.”
Scientists implanted adult human stem cells — known as intermediate induced pluripotent stem cells — into pig embryos and allowed them to grow for four weeks (…)
(…) Most of the organ cells would be human. By injecting pig embryos with stem cells from the person who will get the transplant, the problem of rejection should be minimized, said another Salk researcher, Jun Wu. Daniel Garry of the University of Minnesota, who is working on chimeras but didn’t participate in the new work, called the Cell paper “an exciting initial step for this entire field.”
Here’s what the new paper reports:
Scientists used human stem cells, which are capable of producing a wide variety of specialized cells. They injected pig embryos made in the lab with three to 10 of those cells apiece, and implanted the embryos into sows. At three to four weeks of development, 186 embryos were removed and examined (…) (source)
(..) Animals with cells from different species are called chimeras. Such mixing has been done before with mice and rats. Larger animals like pigs would be needed to make human-sized organs. That could help ease the shortage of human donors for transplants.
The Salk team is working on making humanized pancreases, hearts and livers in pigs. The animals would grow those organs in place of their own, and they’d be euthanized before the organ is removed.
Most of the organ cells would be human. By injecting pig embryos with stem cells from the person who will get the transplant, the problem of rejection should be minimized, said another Salk researcher, Jun Wu (…) (source)