Ape-man embryos

Scientists have created chimeric human and monkey embryos

Maria Krivochenko, Naked Science

A team from the Salk Institute in California and their colleagues have created so-called chimeras of man and monkey. They placed human stem cells in macaque embryos in laboratory petri dishes and were able to grow chimeric embryos for 20 days. This research, despite ethical questions, has the potential to provide new insights into evolution. It is also important for the development of new models of human biology and the study of diseases. The work was published in the journal Cell (Tan et al., Chimeric contribution of human extended pluripotent stem cells to monkey embryos ex vivo).

In 2017, Juan Carlos Izpisua Belmonte and his colleagues created the first human-pig chimera. Scientists have incorporated human cells into pig tissue at an early stage of development. But they found out that they have a bad molecular bond. Therefore, biologists decided to investigate chimeras using a more closely related species – macaques.

Chimeric blastocyst of man and monkey.

Scientists have grown macaque embryos in the laboratory. As soon as they were six days old, 25 human induced stem cells were injected into them. A day later, human cells were found in 132 embryos. After 10 days, 103 chimeric embryos were still developing. Survival soon began to decline, and by day 19, only three chimeras were still alive. At the same time, the percentage of human cells in embryos remained high throughout the entire period of their growth.

The researchers analyzed human and monkey cells from embryos. Several connections were found in them, which either turned out to be new or strengthened in chimeric cells. "Understanding which pathways are involved in chimeric cellular communication will allow us, perhaps, to strengthen this communication and increase the effectiveness of chimerism in a host species that is evolutionarily more distant from humans," explained Belmonte, the head of the work.

Next, biologists investigated all the molecular pathways involved in interspecific communication. The main goal is to determine which of them are vital for the development process. Also, this work can pave the way to solving the problem of acute shortage of transplanted organs and to develop new approaches to drug screening. And it will help us better understand early human development, disease progression and aging.

Biologists noted that the work complies with modern ethical and legal principles. "No matter how important these results are for science, it is equally important how we conducted this work, paying the closest attention to ethical considerations and closely coordinating our work with regulatory authorities," Belmonte said.

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