Nobel Prize winners behind the CRISPR/Cas9 revolution

Charpentier and Doudna developed the technology programmed to recognize specific sequences in genes and introduce correct mutations into DNA.
Two middle aged women smiling while greeting each other
French microbiologist Emmanuelle Charpentier (L) and professor Jennifer Doudna of the U.S. pose for the media during a visit to a painting exhibition by children about the genome, at the San Francisco park in Oviedo, October 21, 2015. (Photo: Reuters)

Por Iván Carrillo

Hard to forget that historic scene in April 2000 when then-U.S. President Bill Clinton and then-British Prime Minister Tony Blair announced the first draft of the human genome decoding declaration. It was the dawn of the millennium and the announcement revealed that it was the beginning of a new era.

“Today, we are learning the language in which God created life,” the American president said at the time. The project was conceived in the 1980s, and one of its initiators was James Watson, who discovered the structure of DNA in the 1950s, along with Francis Crick. The plan to sequence the total genome didn’t officially begin until 1990. With the technology at the time, it was predicted that it would take about 15 years to reach the target.

The feat, comparable to reaching the Moon, required the participation of nearly 3,000 scientists from six countries. The most visible face of this adventure was researcher Francis Collins, who competed with scientist Craig Venter in determining the exact order of the pairs in a DNA segment.

Thanks to this research, today we know that the human genome contains about 3 billion pairs of bases found in the 23 pairs of chromosomes within the nucleus of each of our cells. The results were made public so that anyone could freely use them without charge. The genome is now a Heritage of Humanity.

Access to this knowledge has made it possible to advance the treatment and understanding of hereditary and genetic diseases. We have also been able to discover in detail the origins of our species, and new analysis techniques have been developed with minimal cost and time. The Human Genome Project required an investment of $2.7 billion and took 13 years to complete. Today, sequencing this molecule costs an average of $1,000 and is done in 24 hours.

Chemistry Nobel Prize awarded women

If reading “the great book of life” has been an unparalleled feat of humankind, no less so has been the ability to manipulate it in a copy-paste manner, like that used in word processors. For this, researchers Emmanuelle Charpentier, from the Max Planck Institute for Infection Biology in Berlin, and Jennifer Doudna, a scientist at Howard Hughes Medical Institute and principal investigator at Gladstone Institutes, received the Nobel Prize in Chemistry on October 7th.

They developed a technology that functions like molecular scissors programmed to recognize specific sequences in genes and introduce correct mutations into DNA to replace damaged parts. In an interview during the 2018 Kavli Prize awards in Oslo, Norway, the scientists gave TecScience details about this technique:

What is CRISPR/Cas9 and how does it work?

Emmanuelle Charpentier (EC): It’s a technology that facilitates genetic modification in a wide variety of cells and organisms, functions as “molecular scissors” that are programmed to recognize specific sequences in genes, and helps to perform what we call pre-search editing, i.e. the possibility of introducing mutations into DNA, correct mutations, replacing parts of DNA with other parts of DNA, replacing one gene with another gene, in every cell or organism that can be worked with ethically. It’s a very revolutionary technique because it allows us to make modifications to DNA. It’s a very powerful technology.

What are the main uses of this technique?

Jennifer Doudna (JD): Currently this technology is used worldwide in research to understand the genetics of living beings and to generate changes in plants, animals, and insects and allows scientists to understand the genes that make organisms the way they are. In the future, we anticipate that this technology will be used to cure genetic diseases in humans and also to modify the genetics of plants, which will allow them to resist climate change and pests, and even make plants more nutritious.

What impact can this technology have, for example, on the food industry?

EC: It’s very important for food production. it allows us to produce clean crops, that is, plants that have been modified with CRISPR/Cas9, but what we buy at the end of the process is something that hasn’t received any DNA foreign to the genome of the plant. It’s a technique that allows for a lot of precision in modifying a plant’s genome.

And, specifically in the area of health?

EC: This technology has already had a big impact, since you have to understand that research needs to be done for the development of new medicines to find out the cause of many diseases and to find ways to identify the targets for new medicines. At this point, it’s critical to have genetic tools that help us better understand the function of genes or the molecular or a cellular mechanism that explains how diseases develop, and as a technology it allows us to develop a number of filters for finding new targets for new medicines and therefore new models of diseases to be able to test these medicines. CRISPR/Cas9 is already used in this regard.

But, what is also very interesting is that there’s development of this technology as a direct treatment in the field of immunotherapy in cancer, in which certain types of cancer can be cured with immune cells that are reprogrammed to recognize and destroy cancer cells. These cells have to be genetically designed to specifically recognize these cancer cells, and CRISPR/Cas9 is used for this.

Another application case is directly in therapy because of the possibility that CRISPR/Cas9 has to correct mutations that are the cause of certain genetic diseases. There are several clinical trials that have already started working in this direction. It’s a long way from knowing that the technology is useful in this field, but let’s hope that in the next five years we will have proof that CRISPR/Cas9 can cure some genetic diseases.

I also know that it plays an important role in pig-human transplants. Yes, yes, CRISPR/Cas9 can be used for transplants.

Understanding molecular scissors

People have a lot of curiosity around this kind of technology. What’s important for them to know?

EC: It’s important to communicate that technology is very useful for biologists, for scientific development and research, to benefit health, crops, and for wellbeing. The notion of genetic modification can be understood in a different way because it allows for the production of clean crops in a safer and more accurate way than any other type of genetic modification used before or than with the use of pesticides. While one might imagine some sci-fi scenarios, the technology can do many things, but there are also many other things it can’t do. It’s just not there yet.

What have been the big challenges in developing this technology?

EC: The challenges have been few and that helps to understand why this technology developed so quickly and was adopted by the scientific community. There are two things. There was a real need for biologists to have technology that would facilitate genetics research in cells and organisms. And the second is that this technology is based on an existing defense mechanism in bacteria. They defend themselves against infections with their own viruses, and the mechanism that we understood in the laboratory was so natural, so simple, and at the same time, sophisticated enough to apply it quickly, changing the natural process very little to be able to modify the DNA and DNA expression in many different ways. This is why the technology has been so successful.

How do you do your work when several labs in the world are looking for the same thing?

EC: For this study, we have two collaborations. First, we analyzed the components of the system, and then we collaborated with a group in Germany for the first part, which was to understand the mechanism. And then for the second part, to find out how the mechanism works, I collaborated with a group from the University of Berkeley to learn more about the structural part of the system.

One needs these collaborations because questions arise that go beyond the mechanism and one ends up needing to collaborate. It’s part of the daily life of scientists for different purposes because collaborations can help in certain kinds of experiments or equipment that you might not have, because there is an expertise that you don’t have, or simply because you want to collaborate with someone to understand more things, and you end up collaborating on other aspects. It’s part of the life of a scientist, and it’s very important. In Europe, for example, there’s a lot of funding that is only granted for collaborations.

We need to show that we’re able to form a team of scientists asking questions about biology because we’ll find answers quicker, and we’ll be able to receive help. There’s a big demand for collaborations at funding agencies.

What are the most important bioethical implications of the project?

JD: I’m very interested in the ethical implications of biological editing because it’s a technology that for the first time allows humans to have control over the genetics of all the organisms in our environment, as well as our own. It allows humans to control our own evolution. If we think about the implications of this, they’re very profound. I’m involved in numerous international talks about the responsible use of genetic editing, and I encourage scientists to engage with each other, as well as with the community at large.

As a scientist, do you have any specific concerns about the use of this technique?

JD: I think there are three areas with specific ethical challenges. One is embryo editing, DNA modification in a way that allows traits to pass on to the next generations. This increases the possibility of eugenics, designing humans to have certain qualities or traits. This application is very delicate and should be thought out very carefully, and we must decide what we’re going to do with that as a society. Secondly, there’s agriculture, where it can have many potential benefits but could also cause harm, so you also need to be careful. The third is the editing of the genome in organisms that are released into the environment, for example, in insects. This may be beneficial if we can reduce the transmission of mosquito diseases, but it could also have unforeseen environmental effects.

Can we say that CRISPR/Cas9 accelerates the pace of evolution?

JD: We can now make changes to genomes at will and allow organisms to respond to them, so it does have major implications. On the one hand, it has the potential to cure diseases and allow us to understand the genetic bases that produce them, but it can also generate harmful changes that we must be very careful about.

We need to understand that it’s not that we’re introducing something foreign into our DNA, but that it works with what is already written…

JD: It’s important that we understand how this technology changes DNA. Essentially, it does so in two ways. One is by making alterations in DNA without introducing any genetic material, something very similar to changing a letter in a text or removing a phrase from a document you wrote. Another way is by improving the way cells introduce foreign DNA into the organism’s genome, in a way that a cell’s life code can be modified with genetic editing by inserting new pieces of DNA sequences, new paragraphs, and again this can be used with major benefits but should also be used very carefully.

Moments of discovery

How do you feel when you know that you’ve played such an important part in the development of this technique?

JD: I’ve had certain moments in my scientific career that I call “moments of discovery”, moments when you’ve discovered something or a revelation from the natural world that’s exceptionally exciting, and this was that way, doing this research in my own lab. This was a study conducted by a researcher, Martin Jenik, who did experiments to understand how the CRISPR/Cas9 protein cuts DNA, how it can find a DNA sequence and make a precise cut, and that triggers editing. Once we knew how it worked, we looked at each other and realized that it could be an amazing technology. That was a moment of revelation that was so exciting that I can still feel how the hairs stood up on the back of my neck, thinking, “Wow, this isn’t just a significant biological discovery. This will have important implications for the future.”

I grew up in a small town in Hawaii and didn’t know anyone who was a professional scientist except my teachers at school. But I love science, math, and understanding the natural world and dreamed of becoming a scientist, someone who spends her life trying to understand small pieces of the natural world. For me, it’s been an amazing experience going through all the work we did with CRISPR. Now, with Marie Charpentier and everything that’s coming in the future, it’s a really exciting time.

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