The woolly mammoth has been extinct for more than 4000 years. Now scientists are talking about bringing it back with the help of a powerful gene-editing technique called CRISPR-Cas9.
But CRISPR's promise extends far beyond the possibility to resurrect extinct animals. It may also have the potential to boost crop yields and create alternatives fuel sources, protect us from insect-borne scourges like malaria and Zika, and even cure cancer.
“CRISPR is dramatically accelerating the pace of research in nearly every biological field,” says Dr. Feng Zhang, an MIT professor who holds several patents for CRISPR technology. According to Zhang, CRISPR has already changed the way biologists and geneticists do their work.
In short, CRISPR is a genome editing technique that allows researchers to cut DNA at a specific location and add, remove, or modify genetic material with more precision than ever before. The DNA stored in our cells serves as the genetic blueprint for every living organism, determining our structure, appearance, development — and our vulnerabilities. Using CRISPR, scientists can target and move around specific snippets of DNA to rewrite these genetic codes.
The potential of CRISPR is tremendous, but research is still in its early stages. Scientists have several hurdles to leap before these futures become reality.
First, scientists must figure out how to safely deliver CRISPR's gene therapies to humans.
“That’s a big area of current research,” says Dr. Megan Hochstrasser, an alumna of the lab at University of California, Berkeley credited with publishing the first major paper about CRISPR.
Scientists may introduce CRISPR-created genetic material directly into afflicted areas, like the brain or the lungs, or perhaps deliver them via the bloodstream. Even so, scientists are not yet sure how to ensure these therapies are absorbed into cells to do their work.
“You have to find ways to trick cells into taking up DNA or RNA,” Hochstrasser says.
CRISPR researchers will also need to grapple with ethical questions surrounding gene editing. How can we responsibly wield the power of changing the human genome? How are we to know the downstream effects of doing so?
Earlier this month, a report issued by the National Academy of Sciences and the National Academy of Medicine advised scientists to avoid using CRISPR during human experiments in ways that might lead to genomic changes in subsequent generations, unless such changes could be proven safe.
“Every technology raises ethical concerns," says Kevin Esvelt, an assistant professor of biological engineering and leader of the Sculpting Evolution Group at the MIT Media Lab. "The challenge is to ensure that our power doesn't outstrip our wisdom.”
If scientists can safely address these technical and ethical issues, CRISPR could be monumental in its ability to change our world. Here’s a glimpse into what the future with CRISPR could look like:
An End to Killer Diseases
One promising CRISPR application is the potential to cure genetic disorders. Just a single errant gene can create a host of problems. For instance, cystic fibrosis is caused by mutations to a gene known by the initials CFTR, which helps control the movement of water in tissues. This disruption to the gene results in thick mucus collecting in the lungs and other organs that clogs airways and traps infection.
With CRISPR, scientists can find abnormalities in a patient’s CFTR gene, then inject the patient's lungs with bits of DNA that will replace abnormalities in their genetic material.
The method could also be used as a cancer treatment. Researchers in Chengdu, China recently edited immune cells from a lung cancer patient and re-introduced those cells in hopes they would attack the cancer. The trial is ongoing, and we’ll soon see the initial results. Meanwhile, the first CRISPR trial in the U.S., which is focused on T cells' vulnerabilities to cancer, is in its beginning stages at the University of Pennsylvania.
CRISPR could also be used to stop the spread of mosquito-borne diseases like malaria, Zika, and dengue fever. Using CRISPR, scientists can identify and then remove genes that make mosquitoes viable disease vectors, and eventually have those traits bred out of all mosquitos.
In 2015, biologists Valention Gantz and Ethan Bier of the University of California, San Diego successfully used CRISPR to engineer mosquitoes that resist malaria.
Fixing the Donor Organ Shortage
CRISPR could also help fill the demand for donor organs. Every day, roughly 144 people are added to the national transplant waiting list, and 22 die waiting for a match. New research centered at the Salk Institute in San Diego found that CRISPR can help us grow organs in pig hosts.
By using CRISPR to introduce human DNA into the pig embryo, scientists are engineering animals carrying hybrid pig-human organs. So far, researchers have raised these pigs to live only a few weeks in the lab. In the future, we could see entire farms of pigs whose organs could be harvested for human transplants.
Hardier Livestock and Crops to Feed a Growing Population
As the world population swells, so will the amount of food we’ll need to grow. Scientists are looking into how CRISPR can help engineer crops and livestock impervious to drought, pests, weeds, and spoilage during shipping.
So far, researchers have used CRISPR to genetically modify oranges that are less susceptible to the bacterial infection citrus canker. Scientists also tweaked genes in cows to make them more resistant to tuberculosis. And researchers have found that snipping genes in white button mushrooms slows browning while the food is in transit, a change that makes them more appealing to consumers and reduces food waste.
“Areas like these will continue to rapidly produce results that improve quality of life and reduce strain on the environment,” Zhang says.
An Alternative to Petroleum
Currently, we use fossil fuels to power our cars and create plastics. But what happens when that finite supply runs out? CRISPR could be part of the solution.
In a recent study, scientists edited genes in Yarrowia lipolytic, a yeast that converts sugars into fats and oils that can be used in the place of petroleum. Researchers used CRISPR to delete and add genes that improve the yeast’s ability to generate those materials. Producing fats and oils in a lab could pave the way for sustainable biofuels.
Designer Pets and Service Animals
Humans have long had a hand in shaping animal evolution. By selecting for certain traits, we domesticated cows for milk production and bred teacup-sized dogs for companionship. CRISPR promises to make it easier than ever to breed animals with specific traits, and to eliminate undesirable ones.
A new study published in January showed how CRISPR might be used for hardier livestock and service animals: Beagles with CRISPR-deleted myostatin genes grew into super-dogs with double the normal muscle mass. Strength is a highly desirable trait for police dogs, so this gene could be modified in the Rottweilers or German Shepherds that serve in the force.
Among the cutest recent CRISPR results are pint-sized micropig pets, which Chinese scientists bred by using CRISPR to disable growth hormone genes.
In the five years since the first CRISPR studies, the technique has revolutionized the biological sciences. With all these potential applications on the horizon, the next five years are sure to see even more CRISPR-enabled breakthroughs.