US Scientists Breed Mouse-Human Chimera

by Karen Faulkner, Worthy News Correspondent

(Worthy News) – Scientists at the University at Buffalo and the Roswell Park Cancer Institute have bred a new chimera made up of mouse cells and human stem cells, Popular Mechanics reports. Chimeras are living things made up of genetically different tissues, in this case, mouse and human. Chimeras are considered medically important as scientists believe they hold the potential of growing human organs inside animals and thereby shortening waiting lists for organ transplants.

Researchers had injected human stem cells into a developing mouse embryo and, two weeks later, one was born with four percent human cells. According to Popular Mechanics, this is a “major advance,” as human and animal cells do not generally blend together well. Moreover, PM reported: “the breakthrough marks a step toward more advanced genetically modified embryos in the future.”

Reporting their findings in the Science Advances journal, the researchers said in their paper’s abstract: “It has not been possible to generate naïve [human stem cells] that substantially contribute to mouse embryos.” Accordingly, the scientists said, the latest development “may enable applications such as human organ generation in animals.”

Notably, the developing germline tissue which creates eggs or sperm does not contain human cells. Therefore chimeras cannot reproduce.

PM reports that this field of research and development is still at the beginning stages and is unpredictable: in December Chinese scientists developed two monkey-pig chimeras after genetically modifying cynomolgus monkey cells. However, the chimeras only survived for one week.

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