Organ Transplant Breakthrough: Scientists Create First Human-Animal Chimera

Yesterday, the scientific journal Cell reported on the first human-animal chimera hybrid to be successfully created by scientists. The research, attributed to first author John Wu and dozens of scientists in a team led by the Salk Institute, is the first to create a chimera incorporating the genetic matter of both humans and pigs.

The Inquisitr has previously featured human chimera; instances where it is suspected that two initially separate fetuses became fused and grew into one developed person. Scientists and judicial workers have been faced with somewhat rare and baffling paternity and other DNA evidence, where one person appears to shed more than one type of DNA, thought, at least in some instances, to be the result of human chimera.

The Salk Institute group is the first to successfully create a human-pig chimera, the first that contains genetic material from both a human being and an animal.

Pigs run through straw.

“In ancient civilizations, chimeras were associated with God,” Salk Institute researcher Wu was quoted by National Geographic, “and our ancestors thought the chimeric form can guard humans.”

National Geographic explains that there are two ways to go about creating chimera. Traditional recipients of organ transplants are a type of chimera. However, the risks associated with peoples’ bodies rejecting foreign tissue are significant. By combining genetic material at the embryonic stage, it appears that two types of DNA can work together more effectively, creating tissue that hosts may be less likely to reject.

Previously, scientists had successfully introduced the pancreatic tissue of a mouse into a living rat, where it grew successfully, was later removed, and then used to successfully treat mice with diabetes. Stem cells are seen as the key to making the new research a success.

“When scientists discovered stem cells, the master cells that can produce any kind of body tissue, they seemed to contain infinite scientific promise,” National Geographic writes.

“But convincing those cells to grow into the right kinds of tissues and organs is difficult.”

A nine-week old human fetus.

One area of research into the promise of stem cells involves growing organs suitable for transplant in petri dishes. Drawbacks of this procedure include invasive surgical procedures to harvest host tissue to begin growing new organs with and challenges ensuring that organs take the form expected.

Researchers at the Salk Institute discovered that the age of the stem cells used to start growing organs for transplant was a key factor in their success. Perhaps surprisingly, the youngest stem cells, previously seen with the most potential, were less effective than slightly older ones.

The scientists were able to inject human stem cells into both pig embryos and live pigs, allow them to grow for a period, and then remove them. One-hundred-and-eighty-six embryos survived, with John Wu estimating their makeup being one human cell per 100,000 pig cells.

At the moment, this low human/pig cell ratio is seen as the next major hurdle to overcome toward creating a viable process to grow organs that human bodies will not reject. Organs containing one in 100,000 human cells are thought to be too much for humans to tolerate.

The key to growing organs that human bodies will accept is suspected to potentially be increasing the ratio of human cells to animal cells, which could take years to successfully accomplish. However, Ke Cheng, with North Carolina State University and the University of North Carolina, described the breakthrough as “intriguing” and Juan Carlos Izpisua Belmonte with the Salk Institute stated that the new method provides an avenue to “study human embryo development and understand disease,” which may turn out to be “just as valuable as the ability to grow an organ.”

[Featured Image by man_at_mouse/iStock]