How Monkeys with Modified Genomes Could Help Fight Human Diseases

In a world first, researchers in China successfully modified genes in monkeys using a precision technique. These macaques’ genomes were engineered with a precision previously unseen in primates, and the development is making waves—both among scientists searching for disease treatments, and groups opposed to animal testing.

The obvious attraction of using monkeys in this kind of application is that they resemble humans a lot closer than other lab animals, which the authors of a paper outlining the study in the journal Cell explain makes them an “important model species for studying human diseases and developing therapeutic strategies.”

In the past, “GM” monkeys have been developed to glow in the dark thanks to the insertion of a fluorescing jellyfish gene, but that was little more than a proof of concept that we can manipulate monkey genes in general.

Now, it’s all about specificity. In this new research, three particular genes in the monkeys were targeted: one that regulates metabolism, one that regulates the immune system, and one that regulates stem cells. The idea is that, in the future, we could precisely modify monkeys to recreate human diseases that are based in genetics, and then use them as models to develop new treatments.

The idea of a genetically modified monkey might sound far out, but we’ve been heading in this direction for a while. To modify the monkey embryos, the researchers used a fairly new technology called Crispr, which essentially allows scientists to really accurately edit specific genes in what's often characterised as a "cut and paste" technique. It’s a transgenic technology that makes the idea of designer babies a whole lot more feasible, for better or worse, and Technology Review reports that it's already been practiced on mice, rats, and zebrafish.

In this case, it’s too early to tell whether the gene modification has had any effect on the monkeys’ physiology or behaviour, but the researchers have sequenced the genomes of the twin monkeys above and found that two of the targeted gene sites were mutated, and that the rest of their genes remained as expected—it seems the procedure worked as intended. The Guardian adds that pregnancies are ongoing with four other modified embryos.

Unsurprisingly, the news has already met with passionate responses both for and against. Scientists researching devastating diseases have suggested—cautiously—that the technique could lead to medical advances by using primates as models of human disease. The caution, of course, pertains to ethical issues.

Animal testing on the whole is one big ethical quandary, and when you’re talking about monkeys things only get more difficult. The reason monkeys ignite such debate is precisely the same reason they make good test subjects: they’re similar to us, sometimes scarily so.

That means they could be particularly useful in researching diseases that it isn't possible to accurately model in other animals, such as brain disorders (think Parkinson’s and Alzheimer’s), but it also means we arguably have a greater ethical responsibility when it comes to engineering monkeys so that they have undesirable health conditions—after all, humans are primates too.

Following on from that is the issue of genetic modification in humans—something that, so far, has been confined to human cells in a petri dish. Technology Review quoted Wezhi Ji, one of the study’s co-authors, on the potential for a similar procedure in humans: “We believe the success of this strategy in nonhuman primates gives lots of potential for its application in humans, but we think due to the safety issue, it will take a long way for expanding this strategy to human embryos,” he said.