Cloning Milestone: New Monkey Species Raises Ethical Questions
The successful cloning of a new monkey species has sparked debate about the boundaries and ethical implications of cloning.
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.
Since Dolly the Sheep's cloning in 1996, scientists have cloned various mammalian species, but the process remains inefficient. Miguel Esteban, a principal investigator at the Guangzhou Institute of Biomedicine and Health, acknowledges progress but highlights persistent challenges.
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.
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.
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.
Nevertheless, Miguel Esteban underscored the potential benefits of cloning for genetic research. He noted that the successful cloning of various nonhuman primate species serves as proof of concept, offering prospects for enhancing efficiency in cloning techniques.
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.
Lluís Montoliu, a research scientist at Spain's National Center for Biotechnology (CNB-CSIC), provided insights into the cloning of both monkey species.
"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.
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