Cloning Milestone: New Monkey Species Raises Ethical Questions
Cloning just hit another weird, milestone-worthy snag, and this time it’s a rhesus monkey named Retro.
Here’s what makes it complicated, though: Retro is the second successful primate cloning feat, after two identical cynomolgus monkeys in 2018. The team used somatic cell nuclear transfer, the same basic blueprint behind Dolly the Sheep, but the success rate is still painfully low, and the researchers haven’t managed a second live birth yet.
With SCNT still producing developmental problems and only one live birth out of 113 reconstructed embryos, the real question is what happens next when Retro’s story stops being a one-off.
Introducing Retro, a cloned rhesus monkey born on July 16, 2020, who is now thriving at over 3 years old. Falong Lu, one of the authors of a study published in Nature Communications, shared that Retro is doing well and growing strong. Retro marks the second successful cloning of a primate species by scientists, following the cloning of two identical cynomolgus monkeys in 2018.
"We have achieved the first live and healthy cloned rhesus monkey, which is a significant step forward that has turned the impossible into the possible," stated Lu, an investigator at the State Key Laboratory of Molecular Developmental Biology and the Institute of Genetics and Developmental Biology at the Chinese Academy of Sciences. However, Lu highlighted the low efficiency compared to normal fertilized embryos and noted that no second live birth has occurred yet.
The cloning technique used for Retro, known as somatic cell nuclear transfer (SCNT), mirrors the method used to create Dolly the Sheep in 1996. This process involves reconstructing an unfertilized egg by merging a somatic cell nucleus with an egg from which the nucleus has been removed.
Retro is thriving at over three years old, but the paper makes it clear this win came after a long string of embryos that did not make it.
Falong Lu says they turned “the impossible into the possible,” then immediately points out the efficiency problem that keeps haunting SCNT.
Since Dolly the Sheep's cloning in 1996, scientists have cloned various mammalian species, but the process remains inefficient.
The Chinese research team, operating in Shanghai and Beijing, used a modified version of somatic cell nuclear transfer (SCNT) to clone cynomolgus and rhesus monkeys.
They overcame developmental hurdles in early cloned embryos by employing inner cell mass transplantation, allowing the clones to develop normally.
It’s a similar kind of shock to scientists reviving dire wolves after 10,000 years, complete with Game of Thrones hype.
The team’s fix involved inner cell mass transplantation, because early cloned embryos kept hitting developmental hurdles.
The team conducted tests on the new technique using 113 reconstructed embryos, with only one live birth resulting from 11 transferred to seven surrogates, as reported in the study.
"We believe there may be additional abnormalities to address. Enhancing the success rate of SCNT in primates remains our main focus for the future," said Lu.
Zhong Zhong and Hua Hua, the first two cloned monkeys, are now over 6 years old and live happily among others of the same species. Thus far, researchers haven't identified any potential limits on their lifespan.
While Zhong Zhong and Hua Hua are commonly regarded as the first cloned monkeys, a rhesus monkey was cloned in 1999 using a different method. This approach involved splitting embryos, akin to the natural development of identical twins, rather than using adult cells as in SCNT.
Successful monkey cloning could advance biomedical research, especially since studies on lab mice have limitations. Nonhuman primate research, which is closer to humans, has been crucial for medical breakthroughs, including the development of COVID-19 vaccines, as highlighted in a report by the National Academies of Sciences, Engineering, and Medicine released in May.
Even with Zhong Zhong and Hua Hua now over six years old, the study still frames Retro’s success as the start of a bigger ethical and technical mess.
The utilization of monkeys in scientific experimentation is met with ethical considerations concerning animal welfare. The research team asserted adherence to Chinese regulations governing the ethical treatment of nonhuman primates in scientific studies.
However, organizations like the UK's Royal Society for the Prevention of Cruelty to Animals have voiced reservations about the ethical implications of animal cloning. They cite the potential for pain, distress, and high mortality rates associated with cloning procedures.
Cloned monkeys present opportunities for advanced genetic manipulations and disease modeling that are not feasible with wild-type monkeys, which could have significant implications for scientific research and species conservation efforts.
"Cloning primates demonstrates the feasibility of the process, yet the remarkably low success rates underscore the formidable challenges involved," Montoliu remarked in a press statement.
He stressed that such low success rates raise ethical concerns about the necessity and justifiability of human cloning attempts. Montoliu concluded that any such endeavors would be exceedingly difficult and ethically contentious.
Retro might be proof that cloning primates can work, but it also makes the next failure feel a whole lot closer.
Wait until you see the “real human words” videos, after the chimp speech claims were challenged by new vintage footage.
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