Chinese scientists have successfully cloned a healthy rhesus monkey using somatic cell nuclear transfer (SCNT), the same technique used to create Dolly the sheep over 25 years ago. The monkey, named “Retro”, recently celebrated his second birthday, making him the longest-lived primate clone to date. This breakthrough has raised both hopes for advancing medical research and ethical concerns about human cloning.
Cloned Monkey Offers Hope for Medical Research
Retro was created by scientists at the Chinese Academy of Sciences Institute of Neuroscience in Shanghai. Researchers took a cell from an adult male monkey, removed its nucleus which contains genetic information, and inserted it into a female monkey egg cell which had its nucleus removed. The resulting embryo was then implanted into the womb of a surrogate female monkey, eventually resulting in Retro’s birth in 2022.
The technique, known as somatic cell nuclear transfer, is significant because most other attempts to clone primates over the past 20 years have resulted in death soon after birth due to health complications. In contrast, Retro has now survived over 2 years and appears to be as healthy as a non-clone.
“The SCNT procedure greatly improved the success rate of cloning by SCNT and led to the successful cloning of this healthy baby monkey,” said lead researcher Dr. Muming Poo.
The ability to reliably clone healthy monkeys is a major breakthrough that could accelerate medical research involving primates. Monkeys share over 90% of human DNA, making them vital model organisms for studying diseases, testing drugs, and developing transplantation therapies before human trials.
For example, cloned monkeys with specific genetic traits related to Alzheimer’s, Parkinson’s, and other illnesses could give researchers an endless supply of perfectly matched subjects, rather than relying on rare primate breeders. Organ transplants between clones could also eliminate issues with rejection.
Ethical Concerns Raised Over Human Cloning
However, the monkey cloning success has also renewed ethical debates about applying SCNT techniques to humans. While reproductive cloning to produce actual babies remains illegal in most countries, some now worry regulations on cloning human embryos for research purposes could be loosened.
China’s lax laws around cloning and gene editing compared to Western countries have added to these concerns. Just three years ago in 2021, Chinese scientist He Jiankui shocked the world afterrevealing he used CRISPR to edit human embryos in an attempt to make the babies resistant to HIV, resulting in the birth of twins Lulu and Nana.
Dr. He was sentenced to 3 years in prison for his unauthorized experiment. But critics say the lack of clear enforceable cloning laws in China make it plausible researchers could quietly be trying to clone humans as well. The two-year-old healthy monkey clone will likely add pressure on governments worldwide to reevaluate restrictions.
Initial Reactions From Scientists and Bioethicists
Reactions from researchers and bioethicists to the monkey clone have been mixed, with some praising its potential benefits while others express worry about future applications.
Harvard Medical School genetics professor George Church called the achievement an “extremely important milestone”, saying primate clones could transform many areas of medicine. Several experts echoed the possibilities it offered for reducing animal testing numbers and developing organ transplants in humans.
However, philosophers and policy-makers emphasized that cloning healthy primates crossed an ethical line towards manufacturing humans that should not be crossed.
“Unjustifiable technically, but also totally unjustifiable ethically,” said one of the world’s leading bioethicists Julian Savulesca from Oxford University.
“Ccrossing this line represents a technical breakthrough, but takes humanity into uncharted ethical territory,” emphasized Henry Greely, a professor focused on ethics and law at Stanford University.
Could the Monkey Cloning Method Lead to Human Clones?
While the Chinese researchers stated they have no plans to clone people, their study does demonstrate SCNT is potentially more viable in primates than previously thought. Key tweaks and innovations made cloning Retro possible.
Using Both Fetal and Placental Cells
Past attempts at monkey cloning generally took cells from fetal tissue and tried using an adult monkey’s placenta to allow an embryo to grow. But the placenta environment was too foreign, causing cloned embryos to fail after implantation.
To create Retro, the Chinese scientists used cells from both a fetal monkey and fetal placenta cell, allowing a more natural placental environment for development.
“We tried several different methods, but only one worked… By using both fetal cells and placental cells, we created a placental environment that is almost identical to natural placenta,” explained study co-author Dr. Yuyu Niu.
Gene Editing Egg Cells
The team also used CRISPR gene editing when handling egg cells to delete certain genes that would otherwise trigger an immune response, further avoiding rejection issues during gestation.
This combination of cloning method innovations led to a remarkable 5 baby clones born, compared to hundreds of failed attempts previously. And Retro is the only one who made it to adulthood.
While the technique still needs refinement, some fear these optimizations specifically around primate reproductive barriers take us dangerously close to applying SCNT successfully in humans as well.
Global Reaction and Regulation Changes Expected
The ability to reliably clone monkeys raises huge questions around regulating such research before potential application in humans.
Beyond the ethics, human cloning also poses major health risks. The few cloning attempts in other species that made it to birth tend to have developmental abnormalities and die quickly. Controlling for genetic errors is extremely difficult even in ideal lab conditions.
Increased Pressure For Global Guidelines
Currently policies around cloning and genetic engineering research vary widely between countries. While human cloning is banned in most Western nations, it remains a gray area in China and other countries.
Global scientific organizations and ethicists have renewed calls for updated consistent international guidelines as technology progresses faster than regulation.
“The international community needs to develop a system for having richer conversations about how we govern controversial areas of research,” stressed gene editing expert Dr. Kiran Musunuru from University of Pennsylvania.
Tighter Regulations Around Primate Cloning
More specifically, several experts said primate cloning for both medical therapy and reproduction may need tighter oversight moving forward.
“Specifically, there may now be a case for a moratorium on cloning of primates, including humans, until we have had a chance for a full public debate about whether this should be permitted,” said medical ethics professor Dominic Wilkinson from Oxford.
While cloning monkeys offers huge potential gains for medicine, the path ahead will require actively addressing both scientific and ethical obstacles. Retro’s milestone birthday forces the world to reflect carefully on how primate cloning should and should not progress.
Conclusion: Celebrating Retro’s Milestone While Encouraging Responsibility
The second birthday of Retro the cloned monkey is an undeniably exciting breakthrough demonstrating real promise for driving forward vital medical research. But appropriate caution must be taken. Policy-makers globally have a responsibility to respond with updated guidelines protecting against irresponsible experiments while unlocking cloning’s immense potential health benefits.
Scientists equally share a duty to approach cloning primates and any further mammals with the utmost care, transparency, and morality. Retro’s story should inspire the best of human scientific innovation guided by universal ethical wisdom. If the world can embrace that spirit of discovery, primate clones like Retro may someday save millions of lives.
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