- Creating exact carbon copies of a host - how does it work?
- Cloning people gets a step closer: Qiang Sun and Yi Zhang’s breakthroughs
- A big leap forward for cloning - but the process is still inefficient
- Should we be worried? Experts say ‘yes’
In 1996, researchers in Scotland successfully cloned a sheep named Dolly, sparking our scientific imagination and grabbing headlines the world over. Poorly understood by the public, this technology was both the stuff of dreams and nightmares. If the headlines were to be believed, this development promised an end to dreaded diseases and no more long lines for organ transplantation. But it also threatened to cheapen the value of human life and diminish our respect for each person’s uniqueness.
Neither was true, and 25 years passed with little to report on cloning. But now, scientists in China have managed a previously impossible feat: cloning a primate. A team led by Qiang Sun, a researcher at the Chinese Academy of Sciences Institute of Neuroscience in Shanghai, has managed to refine an innovative process that enabled this breakthrough. The plan is to clone long-tailed macaques, a species of small monkey, to study Alzheimer’s cures. The cloning is necessary because when tailoring genetic remedies for this disease, having a stock of identical test subjects is critical. Moreover, previous studies in mice proved ineffective in people because our biology is just too different. To find a cure, scientists need subjects that are as similar to people as they can get, and they need them to be identical to one another, too.
But this discovery has re-ignited old fears. When Dolly was born, ethicists and researchers started sounding the alarm about human cloning, but the tech just wasn’t there. Now with this breakthrough, Sun has demonstrated a technique that’s probably viable for cloning people, and that has experts worried.
Creating exact carbon copies of a host - how does it work?
The technique used to clone Dolly, somatic cell nuclear transfer, works really well in some animals (cats and mice) and very poorly in others (rats and primates). That came as a surprise, as researchers in 1996 expected every cell to respond similarly to nuclear transfer.
Here’s how it works. Scientists take a healthy, unfertilised egg cell and remove its nucleus, leaving the cell intact but literally sucking out its guts. They then implant a new nucleus from the animal to be cloned into the empty egg. As Andy Coghlan explains for New Scientist, “An electric current is used to trick the egg into thinking it has been fertilised, and it starts to develop into an early embryo. When implanted into the uterus of a surrogate mother, the embryo will grow into a carbon copy of the animal that donated the nucleus.” In some sense, after the nuclear exchange, this process isn’t much different than the standard IVF treatments you’re probably familiar with, though the failure rates are much, much higher.
What really makes this cloning rather than IVF is that the host cell contains donor material from a single source, creating an identical twin. There’s no gene-mixing as in ordinary reproduction; what you get is an exact copy of the host. That has advantages for research, especially when you’re talking about genetics. And as we mentioned, for sensitive neurological testing on diseases like Alzheimer’s, cloned mice simply won’t do. For that, we need very, very close relatives like monkeys.
Cloning people gets a step closer: Qiang Sun and Yi Zhang’s breakthroughs
But the problem with this technique for primates like long-tailed macaques and humans is that our nuclei just don’t want to ‘take in’ the new cell. The host egg, once it’s tricked into believing that it’s been fertilised, ‘turns on’ the nucleus, telling it to develop and grow into an embryo. But in primates, the egg can’t switch on the genes needed to make this happen. Until Sun’s innovative technique, primates just couldn’t be cloned. But he and his team found that using harvested cells from fetal tissue was more effective than adult cells. That was the first step. The second was to incorporate the work of a scientist from the US.
Yi Zhang, a researcher at Boston Children’s Hospital and the Howard Hughes Medical Institute, has been researching a chemical ‘booster’ for cloning that stimulates adult cells to develop into embryos, improving previously modest success rates tenfold. His goal is what’s called ‘therapeutic cloning’, a process through which embryonic stem cells that perfectly match a donor can be made, possibly opening the door to custom-grown organ replacements.
Sun took that ‘booster’ and applied it to primate fetal cells, adding “two new ingredients to the soup of nutrients and growth factors that help cloned embryos grow before being placed into the surrogate. The ingredients – messenger RNA and a compound called trichostatin A – awakened at least 2000 genes that are vital for various stages of embryonic development, enabling development to proceed.” With this addition, his team got the new nuclei to develop into embryos, and finally, baby long-tailed macaques named Hua Hua and Zhong Zhong.
A big leap forward for cloning - but the process is still inefficient
To say that this is a massive leap forward for cloning tech is something of an understatement, but the technology isn’t yet where it needs to be. As Philip Ball reports for the Guardian, Sun’s two monkeys “were the only live births from six pregnancies, resulting from the implantation of 79 cloned embryos into 21 surrogates”. Antonio Regalado provides different, more realistic numbers for the MIT Technology Review: “the Chinese teams used 63 surrogate mothers and 417 eggs to make two monkey clones”. Either way, that’s a high failure rate, and it just wouldn’t make economic sense to try this technique yet in human beings. But Sun and Zhang’s successes have experts worried. Is human cloning right around the corner - for real this time?
Zhang doesn’t think so. “No society could accept this … On the other hand, if you are asking me, Can you improve the efficiency even more? Well, the answer is yes. My answer is that eventually, from a technology point of view, human cloning will be possible.” He’s probably being a little coy: the technique that worked on long-tailed macaques would probably have some success if tried with human beings, and in all fairness, human cloning is probably technically possible now.
Should we be worried? Experts say ‘yes’
So should we be worried? The simple answer is yes, according to Jose Cibelli, an expert on cloning from Michigan State University. The technical hurdles at this point are modest, and Sun’s work suggests that it could happen, given money and motivation.
That there’s really no good reason to do it is the only obstacle at this point. As Sharon Begley writes for Business Insider, there’s just no real incentive to clone people. Without money to support such a project, it’s just not going to happen. For instance, the IVF industry isn’t interested in cloning, and as Ball observes, there just aren’t any good reasons to use cloning as a reproductive solution.
Unfortunately, he notes, too, that “It’s not hard to think up invalid reasons for human cloning, of course – most obviously, the vanity of imagining that one is somehow creating a ‘copy’ of oneself and thereby prolonging one’s life. That notion would not only be obnoxious but deluded. Which is not to say that it would prevent someone from giving it a go.” In fact, Ron Gillespie, the founder of a company called PerPETuate that clones pets, admits that he gets requests from people to clone loved ones far too frequently for his comfort. “We’ve gotten many requests … I say we don’t do it. And when people press me where they can do it, I say ‘I don’t know.’ I just totally dismiss it. One of the biggest complaints we have about this is that it is going to lead to human cloning, and people are very opposed to that, beginning with me.” All it’ll take is one rich buyer and one unscrupulous scientist.
The good news is that human cloning is generally illegal, with no less than 50 countries prohibiting it. That’s a good start, but it’s time to have a more robust discussion of why cloning human beings is a bad idea.