Berkeley Talks transcript: Jennifer Doudna on the future of gene editing

Jennifer Doudna: Good afternoon, everyone. It’s a wonderful pleasure to be here on our home campus, and I just feel like I’ve got my extended family here in the room. I have to tell you that when I moved to Berkeley in 2002 I was recruited here from Yale University by some of the distinguished people in this room, actually. And I knew I was moving to an exciting place. I had been very happy at Yale. I was sort of opening the door to a lot of new exciting opportunities and research. What I didn’t think about at the time, but I’ve come to appreciate, especially in recent years, and you’ll see in this lecture, is that our great university is much more than any individual department.

I’m fortunate to work in two great departments here, but there are so many ways that this university has now contributed to my thinking about the future of genome editing, where it’s going in a societal sense, a legal sense, and an ethical and moral sense in addition to all of the opportunities in clinical medicine, agriculture, et cetera. So I feel like I am so lucky to be at a place that has been fostering my intellectual growth in all of those different realms, and I think this lectureship in honor of Dr. [Elburg 00:01:22] certainly is very fitting in the sense that he is someone who has inspired many of us. Reading about his life and his work here at Berkeley is just sort of, to me, epitomizes why Berkeley is such a great place to have the opportunity to work and work with such great students.

So that’s my little tribute to Berkeley, and what I want to do today is I’m going to tell you a story, really, about some research that started here at Berkeley with just a collaboration among colleagues, and then an international partnership with Emmanuelle Charpentier that led in an unexpected direction. And it produced some science that has profound implications going forward in different areas, of course, in medicine and agriculture, but also makes us really think about what it means to be human and what it means to have the power to manipulate the very code of life. And I want to get into some of that today with you, and hoping to talk for about 40 minutes, and then I want to save a generous amount of time for discussion at the end.

To get into this, I wanted to introduce the topic of genome editing by pointing out that a lot of times in science, and this is something I love about being a scientist, we do experiments in the lab because we have an idea about something. We have something we want to test, and the result isn’t something you could have predicted. It takes your work in an unexpected direction. And that was exactly the case for the work that led to the CRISPR-Cas9 method for genome editing, because this was a project that began as a curiosity-driven experiment to understand how bacteria fight viral infection, something that might sound rather esoteric to folks in the room, and yes, it is in many ways.

But it was something that I was curious about, and through that research that we did in partnership with various colleagues, this led to an understanding of this bacterial immune system that allowed it to be adapted as something very different, namely a tool for manipulating the DNA sequences in any type of cell or organism. And this really started with a conversation that I had with a colleague here at Berkeley, Jillian Banfield, and this is one of the great things about Cal, you know, Jill called me one day, probably around 2006 or so, and she said, “Jennifer, I don’t really know you. We don’t really know each other, but you’re doing the type of research that I think could be very interesting for something that I’ve stumbled across in my own work.”

And she proceeded to explain to me that she studied the DNA isolated from different kinds of bacteria and the viruses that infect those bugs in environment, and she’d come across something very mysterious that was intriguing. And that was the fact that many bacteria in their chromosomes, and this is a diagram that illustrated the circular chromosome of a typical bacterial cell, many bacteria have a sequence of DNA in the chromosome that is a storage site for DNA sequences that come from viruses that infect those cells. And these DNA sequences have a distinctive pattern of repetitive elements that flank unique bits of DNA that are stored from viruses, and they were called CRISPRs, so when you see the acronym “CRISPR” even if you don’t know what it actually stands for, now you know that it’s an acronym that is describing this repetitive DNA element that is a genetic vaccination card for bacteria where they store records of past infection.

And what Jill wondered was whether these sequences might in fact be a signature of a bacterial immune system, a way bacteria could prevent future infection by those viruses. And one clue to this was that many of these organisms, in addition to having these repetitive CRISPR sequences, they also had CRISPR-associated genes that encoded proteins of unknown function at the time that were nonetheless always inherited with CRISPR arrays. And so it had the look of some kind of a conserved system that might have evolved over time to do something very specific.

And what we now know, and this is really based on work that was done initially by scientists working in the dairy industry who are studying the kinds of bacteria that are used to culture yogurt and to make cheese, is that in bugs that have a CRISPR system, they in fact can adapt to viruses and protect themselves from future infection. And here’s how it works, so this is a cartoon of a bacterial cell, and if that lucky cell has a CRISPR system in the genome, then when it gets infected by a virus which injects its DNA into the cell and starts to make all of the molecules that are necessary to make more viruses, this cell can in fact acquire a little sequence of DNA from the virus and store it in the CRISPR array in the genome.

And then the cell makes a little copy of that CRISPR array in the form of a molecule called RNA. It’s a genetic cousin of DNA, so it provides the zip code for this system to recognize viruses that might have a matching DNA sequence. And those RNA molecules combined with proteins encoded by the Cas genes to form surveillance complexes that utilize the RNA sequence, the letters in the RNA, to find matching sites in DNA molecules. And when those matches are found, then the Cas proteins are able to cut up that foreign DNA and get rid of it, so it’s a great way for bugs to adapt to viral infection.

And the amazing thing about these pathways is that Jill Banfield’s work, and others who are working in this field, very small field at the time, were in fact uncovering many different examples of these CRISPR pathways. It’s not one immune system, but in fact many, and I wanted to show you this great picture from Jill’s lab, so these are two members of Jill’s lab including Christine He, who is a joint postdoc between our labs. And what these lucky lab members get to do in their work is go out on field trips like this and they collect samples of ground water, samples of soil, and they are able to filter those samples and isolate the bacteria that might be growing in those environments.

And then the DNA from those bugs is sequenced and used to look for new examples of CRISPR systems as well as lots of other kinds of interesting pathways that these bugs might be using, so it’s a field that’s known as metagenomics. And it’s really interesting, because we often don’t even know what these bugs are. They’ve never been identified by scientists or cultured in a laboratory, and nonetheless, by doing this kind of metagenomic research, you can get a lot of information about the lifestyles of these organisms.

And so this kind of work has uncovered many different flavors of CRISPR-Cas immune systems, and I’m showing you here a slide that just illustrated in cartoon fashion the collection of different kinds of CRISPR-Cas enzymes and proteins that are part of these pathways. And I just want you to notice that, overall, we can divide these systems into two categories known as Class 1 and Class 2, and the thing that really distinguishes them is the fact that the Class 1 systems consist and require multiple proteins that provide protection from viruses. Whereas the Class 2 systems each consist of a single large gene that encodes a big protein that’s responsible for protecting cells, so rather than requiring a whole set of proteins, one protein does everything to protect the cell.

And so it was really that sort of thinking about this difference in these types of CRISPR systems in nature that led to a partnership that I established with Emmanuelle Charpentier’s lab back in 2011 to investigate the function of a particular gene, a gene encoding a protein known as Cas9. And we were both at a conference together. We were scientists who came from different parts of the world. We were coming from very, very different scientific backgrounds, but when we met at a conference we were both interested in the same question, “What is the function of this Cas9 protein?” It must be a really interesting protein if it could provide this kind of programmable protection against viruses.

And that embarked my lab and Emmanuelle’s lab on a wonderful collaboration to answer this question. Two scientists working with us, Martin Jinek, postdoc here at Berkeley in my lab at the time, and [Christoph Chiwensky 00:10:40] in Emmanuelle’s lab working in Vienna at the time, figured out that Cas9 is an amazing enzyme that has the ability to recognize segments of DNA at sites that match a 20-letter sequence in the guide RNA. And remember that this would be a RNA molecule coming from and derived from integrated pieces of DNA in the CRISPR locus that record a past viral infection, so by definition, these RNAs are able to recognize matching DNAs that comes from those viruses.

And so in this cartoon right here, I hope you can see that. Here you can see the laser pointer. This piece of RNA provides the address for DNA recognition, and when the protein, which is shown in blue, recognizes that segment of DNA, it’s able to unwind the DNA duplex, and then two chemical centers in the protein generate a double-stranded break in the DNA, and that’s really how it works. So in bacteria, when that break is generated, the bacterial cell is able to quickly then degrade those ends of the DNA, and if that’s a piece of viral DNA, then the virus goes away.

And importantly, by doing these biochemical experiments where we had purified the Cas9 protein and were figuring out what were the essential components for this RNA-guided DNA recognition and cutting, Martin and Christoph figured out that the system requires a second kind of RNA. This little molecule here shown in red called the tracer, which creates a structure for binding to Cas9, so in the laboratory it was essential to have both of these types of RNA molecules present with Cas9 for targeted recognition and cutting of DNA to work, and we quickly show that’s true also in cells.

Now, Martin Jinek, being a terrific biochemist, was very interested in kind of the minimal components of this system, and he was busily kind of figuring out what the essential parts of these RNA molecules might be. And he realized that you could actually link together the part of the RNA that provides the address label with the part of the RNA that provides the handle for Cas9 assembly, and this created what we call the single guide form of the RNA that, in a single molecule, could provide both the ability to bind to DNA and the ability to recruit this Cas9 protein for cleavage.

And when we did this experiment and saw that these single guide RNAs could easily be altered on this end to recognize different places in a DNA sequence, whether that DNA molecule was a very short molecule tested in the test tube. Or whether it was an entire chromosome of a cell, we realized that our work that had started as a curiosity-driven project to understand the bacterial immune system, had the potential to go in a very exciting and very new direction. And that’s because by introducing a targeted break to DNA, it could be possible to trigger genetic changes to be made to the DNA in the process of repairing that break.

And that’s because in many other labs around the world, really over the past several decades, people have been studying the process of DNA repair, especially in human cells where misrepair of DNA can lead to cancer and other problems, and so there’s lots of interest in understanding how this works. And it was appreciated that in our cells, and in plant cells, and other kinds of animals and plants, when double-stranded breaks occur to the DNA, rather than leading to degradation like happens in bacteria, instead the cells can recognize that break and fix it. And they repair it by either introducing a very small disruption to the DNA, the process of pasting those ends back together, or by integrating a new segment of genetic information is a template DNA molecule is available in the cell, something that is easy for scientists to introduce in a research setting.

And so by doing this, if you had a way to introduce a targeted break to a genome, you could actually carry out something that at the time was called genome engineering. You could literally change the DNA sequence at a particular place by inducing the cell to make that change in the process of repairing DNA. And I wanted to show you a video that was created by a wonderful colleague and scientist at University of Utah for us, Janet Iwasa, that shows how this works when we put these molecules into human cells. So when we go into the cell, of course the DNA in a human cell is inside the nucleus, it’s packaged as chromatins, so it’s wound around histone proteins, and amazingly, the Cas9 enzyme can use its guide RNA to find a matching sequence of DNA in the genome.

And when that match occurs, the protein is able to unwind the DNA. It forms a hybrid with the RNA, little helix inside the protein, and then the DNA is cleaved and the broken ends handed off to other enzymes in the cell that can repair the break by, in this example, inserting a new segment of genetic information. So it’s a very powerful tool, and amazingly, after we published this work in the summer of 2012, very quickly labs around the world started to adopt this method for genome engineering, and quickly that word turned into genome editing. Because we all realized that with this technology it became much easier now to change the sequence of DNA precisely and accurately, and it really became a democratizing tool that allowed labs to do experiments that in the past would have been prohibitive for various reasons, whether due to expense or time or just technical difficulty. Now, suddenly, those kinds of experiments became a lot easier.

For those of you in the room that if you’re not reading the scientific literature everyday, just to give you a sense of what’s happened over the past few years, this technology just took off incredibly quickly, and I wanted to just show you an illustration. This is actually from the Elsevier journal website, just showing the numbers of publications over the last few years with different technologies for genome editing. And so before, there was CRISPR, there were tools for altering genomes that were based on having to engineer proteins that could cut DNA precisely, and these are shown in these three examples here. And these were adopted initially, but once the CRISPR technology became available, it really took over.

And the reason is that it’s just a lot simpler and faster to be able to change a molecule that provides the address label for a single protein, Cas9, is the same in everybody’s experiment, whether they’re working with human cells, or wheat cells, or zebrafish, or anything else. They just have to change the address level, this RNA molecule, something that is relatively trivial to do with molecular biology methods. And so for me as a biochemist and a structural biologist, this experience of doing this work and then sort of being part of this revolution, really, that’s happening where we have a new technology that’s incredibly enabling, has been very exciting and also incredibly challenging.

And I wanted to share with you just a few things that we’ve been working on in the lab, and just very briefly tell you some of the questions that we’re still asking in the laboratory and trying to understand the answers to. And then I really want to dive into where this is all going in terms of what’s going to happen. How is this going to affect all of our lives in the future, and what do we do about it? How do we think about it? And so to start with a little bit of the science that we’re doing, so we’ve always been fascinated with how molecules work, and I still find that every morning when I wake up that’s usually the first thing on my mind, is I’m thinking about experiments that I had been discussing with the members of my lab, and our collaborators and colleagues. And I’m wondering what are the results of those experiments.

And one of the things that we’ve been puzzling over is really the understanding the mechanism by which this Cas9 enzyme is able to function as an RNA-guided protein, so think about it. This is an incredible molecule, right? Because it’s a protein that has this little address label, and somehow by a mechanism that is still being dissected it’s able to interact with the DNA in a cell so precisely that it finds a 20-letter sequence in the out of all of the billions of base pairs of DNA, three billion, for example, in the human genome. And it finds that 20-letter stretch, and most of the time it does it pretty accurately, and it makes a cut in the DNA.

And so how does that work? And so we’ve been studying this using a variety of techniques including X-ray crystallography, electron microscopy. Those are techniques that show us the structure of molecules and what they actually look like, as well as all sorts of ways of proving the behavior of these molecules. Whether it’s in the test tube in the lab, or whether it’s actually in living cells. And that work has showed that this is actually 3D-printed model of Cas9. It’s based on a crystallographic structure that was actually solved by my formed postdoc, Martin Jinek, who’s now a professor at the University of Zurich.

And what this shows you is the white protein, which is the white part of the model here, Cas9, with its guide RNA, the orange molecule, that’s the address label, holding on to a DNA molecule that is unwound inside the protein so that it can make this precise set of base pairs with the RNA. So there’s a transient RNA-DNA helix that forms inside Cas9, and when that occurs, the protein has a sensor that now triggers cutting of the DNA. We understand now a lot about how that works by a lot of … And I wish I could have several hours to tell you all of this, but this is really all of the work that’s been done over the last six years in our lab by a whole collection of undergraduates, graduate students, postdocs and technicians who have been able to sort of tease apart how this actually works.

And I wanted to show you another. This is just a representation of a structure of a related enzyme called Cas12. It’s also an RNA-guided DNA-cleaving protein. It’s a member of the related CRISPR-Cas system, and this shows you how, again, this protein is structured so that it holds on to the orange molecule, the guide RNA, and as the DNA traverses the protein, it unwinds inside the enzyme to allow access to each strand of that DNA double helix so that cutting can occur. Now, these proteins, amazingly, are able to open up the DNA duplex, but they do it without any external energy source. They somehow coax apart those DNA strands.

And that’s a fundamental question that we’re still puzzling over, how does that work. Because it’s critical for the mechanism of these enzymes that they are able to gain access to the DNA helix, and not only that, unwind the duplex so that it can be cut. And one of the things that’s emerged from our research over the last few years is that these types of proteins, and I’ll show you this example for Cas9, are enzymes that they’re able to change their shape. They’re sort of like shape-shifters, and this is an example that shows a comparison of different crystallographic structures that we have of Cas9, and the animation starts with the protein alone morphing to this shape that it forms when it binds to the guiding RNA.

Once that occurs, there’s a channel in the protein that is available for binding to DNA, so that’s a really big rearrangement of the protein structure, and once the DNA binds in this central channel there’s additional rearrangement of the protein to accommodate that RNA-DNA helix. And then finally, this part of the enzyme right here, this yellow piece, swings into position so they can actually cut the DNA. This was initially a model for how Cas9 might work to sort of a construct in our minds for how it might work, but we’ve been able to test all of these steps using different chemical methods and we now feel very confident that this model is correct. And this is really an enzyme that’s designed to grab on to DNA, disrupt the helix probably in part by changing the shape of the enzyme that pries apart those DNA strands. And then only when it’s engaged with a correct matching sequence that matches that guiding RNA does the cleaver position itself to actually make a cut in the DNA, so it’s really an amazing little molecule.

I wanted to talk now about what this kind of tool is enabling, and I’m going to focus on three different aspects of applications of genome editing. I want to talk a little bit about applications in public health, applications in agriculture, and then finally, applications in biomedicine. Because one of the amazing things about genome editing, if you think about it, every living thing that we know of on our planet has a nucleic acid that encodes the genetic information, and for cells that’s DNA. So given a tool like this that turns out that this is a technology that is enabling in many different areas of biology.

And so people, of course, have been thinking about how you might use a tool that allows changes to be made to DNA precisely and accurately. How do you use that in ways that are going to solve real-world problems? And what’s so interesting is that it’s allowed incredibly creative and interesting things to be either done or to get into the pipeline, but it also raises, I think, some very profound challenges in terms of the societal implications of this work and the sort of ethical issues that are coming up, as well as issues of equity and how we think about a technology that’s moving so quickly in the laboratory. And you saw with that chart I showed you of publications, there’s now I think the last time I typed CRISPR-Cas9 into PubMed, which is our search, sort of the library of medicine. I came up with close to 10,000 publications just in the last two years, so it just gives you a sense of how exponential the growth has been in the use of this tool.

But that’s moving forward much faster, I would say, than any of the grappling with these kinds of challenges that we’re doing, and so this is why it’s so important to have people thinking about this and engaging in what it means to have a way to literally control the code of life, and to control the evolution of organisms including ourselves. In public health, so one of the things that’s happened is that people have appreciated that you could use the CRISPR-Cas system in ways that will have a clinical impact, but don’t necessarily involve using genome editing directly in people. And this is an example here where scientists are using gene editing to alter the DNA of animals like pigs that are envisioned to be good organ donors for humans, and using it in two ways.

One is to remove endogenous viruses from the pig DNA that could otherwise potentially infect humans that received organs donated by these animals, and the other is to make the organs in these animals more human-like so they’re less likely to induce an immune reaction. And that’s actually work that’s going on both in academic labs and also in companies now, so that’s an area where this is something that, I mean, a few years ago I wouldn’t have ever imagined. You know, something we were involved in having that kind of effect, and yet this work is moving forward really quite quickly, and I think that most people would agree that this is an exciting potential application of this that could solve a real problem, which is the scarcity of organs that are necessary for donations.

And then another area of interest in public health is an area where I would say there are both very interesting opportunities, but also some real ethical challenges, and that’s in an area that we call gene drives, and maybe some of you have seen this in the media. In fact, there was just a story recently on NPR about gene drives in mosquitoes, and I just wanted to very briefly explain what a gene drive is. It’s basically a way of introducing a genetic trait very quickly through a population of organisms, and it requires an efficient way of integrating genetic information into the genomes of these organisms. And this is a diagram that is adapted from a recent article in Science News that just shows how this works in an insect population.

Normal inheritance works like this where we have traits that are in each of the parents, and they have progeny, and those traits are inherited generally in sort of what’s called a Mendelian fashion, that a trait in this animal doesn’t take over the population, it’s simply inherited according to this lineage. But if we have a gene drive in place, and this is something that can be enabled with a gene editing technology like CRISPR-Cas9, now we have a way that, if this animal has not only a particular genetic trait but that trait is coupled to the gene editor, then every time it gets into an animal it will tend to get into animals that don’t have that genetic trait. And so you follow this through this population and you can see that, very quickly, virtually all of the organisms have this particular genetic trait. We’re no longer relying on Mendelian inheritance.

Why would this be useful? Well, people envisioned that you could use such a technology to control the spread of mosquito-borne diseases by creating animals in the wild that are either unable to spread the disease or are sterile, for example, which might lead eventually to extinction of the population if you took it to that extent. And so there’s I think both incredible excitement about the potential for this, but also a growing recognition that this could have profound impacts in the environment that need to be evaluated, and we need to be very careful about taking steps that might be difficult to reverse once they get unleashed. And so that’s one of the kinds of challenges that a technology like gene editing is now bringing to the floor.

I wanted to also speak a little bit about agriculture, so in agriculture I personally think that this is probably the area where gene editing will have the widest global impact in the near term. Because everybody has to eat and there’s lots of research being done to alter plant properties that will allow plants to resist drought, to resist disease, potentially to be more nutritious, and to do that using gene editing so that genes can be very precisely altered without requiring years of breeding as well as all of the genetic variations that typically go along with traditional breeding approaches for plants.

This is an example from a research lab at Cold Spring Harbor Laboratory, Zach Lippman, who published a paper showing that you could use the CRISPR-Cas9 system essentially as a rheostat to dial up or down the numbers of fruits that are produced by plants such as tomatoes. And he’s done a lot of work on this showing that he’s really impacting the genome at a place that is highly conserved across different kinds of plants, so you could start imagining being able to control crop production in many different kinds of crops using this sort of a strategy. Which sounds very exciting.

And then there’s work that was done at Penn State University by another academic research group that was able to use CRISPR-Cas9 to knock out one gene, a single gene, just made a one gene disruption, that creates a trait in these mushrooms that prevents them from turning brown when you cut them open. And so this was sort of a novelty when they initially did this, but again, if the idea is that it demonstrates how straightforward it now is, at least in some settings agriculturally, to make these kinds of targeted changes to plants. And the big question is, or a big question, is how we all feel about that. How do we feel about going to our local farmer’s market or grocery store and picking up some mushrooms that have been edited this way? Are people going to accept that or resist that?

And I’ve discovered that depending on the country that you live in, the answer is going to be different, at least from an environmental governmental perspective, because in the United States, the US Department of Agriculture has decided that any kind of gene editing that leads to genetic knockout, not introducing new genetic information, is not to be regulated. And it’s not considered a genetically modified organism because it doesn’t contain any foreign DNA, but if we go over to Europe it’s very different. In Europe, the ruling has come down in the last few months that organisms such as the mushroom would be considered a genetically modified organism, and those would be regulated very strictly or perhaps not even allowed on the market there. So we’re at this very interesting moment where countries are having to grapple with this, and it will affect global markets for products that are produced from everything from home farmers to big commercial farming operations.

And then finally, I just want to turn to biomedical applications, and this is actually a slide from some of our own work, so one of the amazing things about gene editing is that even labs like mine that are very firmly in the camp of working on purified molecules and thinking about mechanisms, have been enabled to do things that we could have never imagined doing in the past. And this is actually an experiment done by a recently graduated or departed postdoc, Brett Staahl, who was able to show that he could make modified forms of CRISPR-Cas9, this little molecule diagrammed here, and inject them into the brains of mice that had been tagged with a gene that turns red when the DNA is edited precisely. So that’s a very nice marker that tells us when and where cells in the brain have received a DNA edit.

You can see here that in this experiment when these Cas9 molecules were injected in two places in the mouse brain, we got a fairly large volume of cells that received a precise DNA edit, and we’re excited about this because we’re actually now working with people at UCSF to ask whether we can use this strategy to treat neurodegenerative disease. And also to deliver molecules into tumors that could be beneficial for cancer patients, something that a few years ago I wouldn’t have imagined that I would be involved in exciting work like that. And then there’s also potential to do things that are outside of directly delivering gene editing into patients that involve detection of disease-causing DNA, and this is using CRISPR-Cas molecules as diagnostics, something that several students in my lab pioneered, really, with their careful work, understanding some of the sort of side functions of these Cas proteins really. And then recognizing that those activities could be harnessed as diagnostics.

So those kinds of applications sound like things that I think all of us would agree are worth moving forward, and don’t really have ethical challenges beyond any sort of their normal ones that we might think about for developing therapeutics. But what about editing the human germline, and this is an idea that really came up very, very early in the whole field of gene editing, because people recognize that if you could make changes to what’s called the germline, that means in embryos or eggs or sperm, that you could actually introduce genetic changes that would become part of an entire organism. And not only that, they become heritable, so they can be passed on to future generations.

This picture was on the cover of The Economist a few years ago under the banner “Editing Humanity”, and they had a whole sort of article imagining what would happen if you could actually do this, right? And so just to explain this a little bit more clearly, I just want to point out for those of you that are not scientists, that we can really define fundamentally two kinds of genome editing. One is called somatic cell editing, and that means making changes to, say, the brains of patients, or any other cells or tissues in a particular organism that are not part of the germline. They don’t get transmitted to future generations.

Versus what’s called germline editing, which involved making heritable changes, and once those changes are introduced it could be very difficult to unchange them, so those really become then part of the whole lineage of that organism and all of its future progeny. And just to show you sort of how this works, so the idea is that you could take a fertilized egg, and this is actually an example from our own Russel Vance, who works here at Berkeley in immunology, so he was one of the early labs to adopt this for germline editing in mice. And this is an experiment in his lab where they took a … You see a pipette tip coming in from the left. It’s holding onto a fertilized mouse egg still at the single cell stage, and you see a needle coming in from the right that’s injecting the gene editing molecules.

And they go into this cell, they edit the DNA, and then as the cell divides and makes more cells and it forms an embryo, then all of those cells inherit that change to the DNA. And so back in 2015 really, and I guess it was even earlier than that, sort of 2014, I started talking with a number of my colleagues here at Berkeley about this and I found myself lying awake many nights thinking about the potential for this technology that I’d been involved in developing being utilized in this fashion. And I started to feel very uncomfortable about it, because it seemed to raise a lot of fundamental questions about not only who we are as human beings, but also the things like eugenics and societal inequity, something we’re talking a lot about now.

And who decides who would have the access or ability to use that kind of genome editing, and is it right to use it at all? With some encouragement from colleagues, we started through the Innovative Genomics Institute here. We held a small meeting up in the Napa Valley in January of 2015 to discuss this question, and that led to a much larger meeting sponsored by the National Academies of Science in the US, the UK, and China to discuss this, and ultimately resulted in a report that was released in now almost about two years ago. Shown here about human genome editing, and in particular, human germline editing, what did it mean, who should be able to use this, and what were the criteria for proceeding if some scientist had this idea for using this application in human embryos.

And even then, it sort of seemed a little bit science fiction-y to me, and I knew the potential was real but I sort of maybe was a bit under the illusion that scientists around the world would respect the guidelines that were put forward by this report. But then in around the end of November of last year, I received an email, it was I think the day after Thanksgiving, with the subject line, “Babies Born.” And the email was from this fellow He Jiankui, who is a scientist in China who I had encountered on a few occasions. I didn’t know him well. In fact, he visited Berkeley a couple of times, and he told me in a very terse email that he had been involved in a clinical study where they used CRISPR-Cas9 to make changes to the genome of babies who had actually been born.

And as circumstance would have it, we were actually all on our way to Honk Kong for the second international meeting on human germline editing, and it was apparent to me that his intention was to announce his work at this conference, and that’s exactly what happened. And I’m sure all of you, unless you’ve been asleep for the past few months, you’ve probably seen articles about this because it’s been written about quite a lot. And it’s really brought to the floor this question of using CRISPR-Cas9 or any other gene editing technology to alter the DNA of humans in a heritable fashion.

Just so that you are aware of what was actually done, and maybe we’ll discuss it a little bit, I wanted to show you this picture, which was actually from the Twitter feed of a colleague of ours, Sean Ryder at the University of Massachusetts, who did a really service for the scientific community of going in and analyzing very carefully the actual claimed DNA edits that He Jiankui reported completing in these twin girls that were born. And what Sean Ryder showed is that although the stated purpose of this application of germline editing in these girls was to remove a gene called CCR5, or disrupt this gene, that allowed HIV virus to infect cells. So his stated purpose was to give these girls protection against future HIV infection, something that sounds reasonable.

It turns out that the actual edits that were introduced into these girls are changes to the DNA that have actually never been seen in humans at a detailed level. These exact edits have never … These changes have never been observed in humans, and in fact, they’ve never been tested in animals. And so at the top is the unmodified sequence of the gene. This shows a naturally occurring deletion called Delta 32 that has been observed in a few people and was the tip-off that this is a gene encoding a receptor protein for HIV. But down here are the actual genetic changes that were created by He Jiankui in these twin girls, and what you can see is that these do not look like this, right? And so even if you don’t look at the details there, you can see that they’re different.

And so that means that what he did was to actually make changes to the DNA, and then implant those resulting embryos so that they resulted in pregnancies and live births, such that the resulting people, these young girls, have changes to their DNA that have never been tested. It’s really a profound thing to think about, and I can tell you that when I was sitting in the audience of that meeting in Hong Kong, I literally had the hairs on my neck were standing up, because it seemed so horrifying, really, what had been done.

And I think that we’re at a point now where we have to think about how to move forward, and I wanted to put this up to point out that the World Health Organization recently announced that they have convened an international forum of scientists who really think hard about where we go from here. Given that human germline editing is now a reality, and frankly, it appears not that difficult to have done, right? Because this He Jiankui is not an M.D., for example, and he was able to find various partners to help him do his work. We clearly, as a scientific community, need to be thinking about what’s the next step here. And this forum is charged with putting in place some more detailed requirements, I would say, perhaps even regulations that would be necessary if anyone in the future wants to proceed down this path. And the national academies in the US are doing the same thing, they’re also in the process of putting together an international forum to look at this.

There have also been calls for moratoria on this kind of application, and maybe we’ll have a discussion about this a little bit, and I have views on this. And I’m just going to close by pointing out three things. First of all, we’re now in an era where we have powerful editing tools for changing DNA sequences precisely and accurately that are both advancing science at a pace that is really, really incredibly exciting, but also raises these profound questions that we really must grapple with as we move forward. Secondly, as I just said, that to really advance genome editing to the next level we’re going to have to understand better, I think, how it works and how to control its activities, and when I saw control, I mean both in a chemical but also in a societal sense.

And then we have to really think hard about what kinds of regulations should be in place that will support science and allow the science to advance as quickly as possible to solve real problems, but will also at the same time limit risk. And I’m going to just stop there, thank people that I’ve had the pleasure to work with. This is my almost current group. Some of these folks have already left the lab. This was taken a few months ago, but wonderful students at every level that have been working with me over the years, great colleagues here at Berkeley. Both scientific colleagues, and also Emmanuelle Charpentier, of course, but also colleagues who are helping us to think hard about these ethical challenges. And then finally, any scientific laboratory is dependent on funding to do our work, and we are extremely grateful for all of these organizations for supporting our work. Thanks a lot.

Speaker 2: It’s a pleasure. First, thank you for that extraordinary talk and the extraordinary work you’ve been doing. We have microphones that we will circulate in the audience, so please raise your hand if you’d like to ask a question, and wait until the microphone gets to you. This gentleman right back here.

Audience 1: You talked a lot about regulations that need to be done for the CRISPR-Cas9 system. Obviously, there have been two sides. One has been to sort of just … Some people would like to say they just completely outlaw CRISPR technology and research, which would be pretty detrimental to the potential that technology has and would also probably be ineffective. And then there’s the other side who wants to completely let loose with the technology and the research, which again, would raise a lot of ethical dilemmas. What do you think is the sort of sweet spot in regulation-wise for a way to respectfully approach this technology ethically and morally?

Jennifer Doudna: Yeah. That’s the so-called $65,000 question, right? You know, you put your finger on it. I think that’s the challenge. My personal view is that it’s probably not enough to just say as some people, you know, there’s an article by Steven Pinker, for example, at one point in the Boston Globe that said bioethicists should get out of the way and scientists should just do whatever they want. And I think that’s going too far, but I think that we need to be thoughtful about putting in place appropriate guidelines, and frankly I would say regulations, that really establish a set of principles that are where there’s some price to be paid if you cross that line. And the challenge is always how to do that.

And of course, science is global now. It’s very hard to imagine quite how we would regulate or maybe enforce regulations globally. But the good news is that there are a lot of smart, dedicated people that are starting to really grapple with that challenge, including our own senator, Dianne Feinstein, who is looking into this and contacted us at the IGI recently about legislation, or at least a statement, that she’s considering putting forward for consideration in the senate. So I think we have to be just very thoughtful and thinking about how we can put in place a set of very clear requirements that might turn into regulations ultimately.

Audience 2: There were news articles that said that scientists are trying to bring back extinct animals such as the wooly mammoth using the CRISPR technology, so I had a couple of questions. What stage is that research at? And secondly, if that succeeds, then what would the pros and cons of that be?

Jennifer Doudna: Yeah. The de-extinction movement is I think what you’re referring to, and it sounds exciting. I think it’s probably more in the realm of science fiction right now, in my opinion. Now, some of my colleagues like George Church who is doing this work might disagree, but I think the likelihood of being able to actually bring back wooly mammoths is going to be challenging, and I’m not sure what the habitat would be for those animals, too. It’s a bit hard to imagine quite where we’re going to put them.

But you raise a great question, and that is I’ve talked to other colleagues who have maybe less grandiose plans for de-extinction, but nonetheless want to explore this. And so there are people that are thinking about, you know, “Could you bring back the courier pigeon,” for example. Or, “Could you engineer birds to have properties that were extent in animals that have now gone extinct?” Again, the way I think about it is what a wonderful tool for doing research and trying to understand the evolutionary relationships between organisms, but I don’t think we’re on the verge of Jurassic Park.

Audience 3: Thank you. My name is Alex. Thank you for a really interesting talk. I think there’s definitely some cultural differences between different countries that are going to make regulation very challenging, just because regulations in one country might not match regulations in another country, whether they’re produced in them currently or not. And so as an outcome, I think it’s feasible that there’s a scenario where this technology is going to be used to edit germline stem cells very quickly and for a while, somewhere where we might not be able to control. And so you being so involved in this technology, how do you think our government and our scientific culture is dealing with the potential outcome of that? Assuming that it will happen and that it’s already happening, what are some of the steps that our government is taking that you might know of that would actually deal with this in some way?

Jennifer Doudna: Well, I’ll just mention three things. I think hopefully everyone heard that question. It’s really just about how do you think about regulation in a global sort of culture of science, and given that the individual countries are going to be approaching this potentially quite differently. I think for me, it comes down to starting with the community of scientists. I think that engaging that community to think together. That’s why I think having these international forums is so valuable to put in place what are seen as essential requirements for any use of, for example, human germline editing by folks in the future, and then using that as a basis for both government regulations.

But also frankly, for the behavior of journal editors, let’s say. You know, people who are involved in making decisions about what kinds of science gets published. And there’s a lot of discussion about like in this case of He Jiankui. He wrote a couple of scientific articles about his work that have not yet appeared in the peer-reviewed literature. Should they be published or should they not be published, you know? And there’s debate on both sides, but I think the scholarly journals will play a big role in disseminating information, and also deciding what kind of work is worthy of being published in those sorts of forums.

And then I guess the third piece is really doing a lot more engagement of people who are outside of the scientific community, and really, it’s a big challenge, because people are… I think, you know, everybody’s busy and CRISPR sounds maybe scary, and maybe it sounds complicated, but I think it’s really key that we have ways of communications. And I’ve been experimenting at the IGI, at the Innovative Genomics Institute, we now have an artist and residence program.

We have artists that have just arrived that are going to be helping to work with scientists to illustrate their work and explain it in a more maybe accessible fashion. And we do a lot of interaction with screenwriters, and science fiction writers, and people like that who are probably going to be doing much more to disseminate information than any of us individual scientists will be able to do. So I think working outside of our traditional comfort zones is also going to be key.

Audience 4: I’m not a member of the scientific community. I’m a political scientist, so I’m interested in public policy, and you talked about balancing regulation and limiting risk, and that’s pretty straightforward. Who’s working on that? The concept of unintended consequences, let’s take those two little girls with the intent of eliminating HIV vulnerability, what’s going on with grappling with unintended consequences of this work?

Jennifer Doudna: Yeah. It’s a great question. The unintended consequences are potentially profound, and so unfortunately, right now I have more questions than answers about that. I think all of us at the meeting in Hong Kong and since then have been wondering what’s being done to follow up on the health of those girls to monitor their progression as they start to grow up. How do we try to understand, as you said, sort of the unintended consequences of the genetic changes that they have received, and how those genes that were potentially, apparently, disrupted, might be affecting other aspects of their health beyond susceptibility to HIV infection.

And then more broadly, how do we think about going forward? I can tell you that there’s tremendous interest in human germline editing. You might be surprised, or maybe you wouldn’t be, but I’m contacted almost daily by people that have questions about it, even people that want to do it and are trying to figure out how and where and when they can get access to it. And it’s not going to go away, and so I think the broader question is how do we approach unintended consequences of this type of genome editing in the future? And there’s no easy answer there. I’m not quite sure how you do experiments to figure that out, right? So it’s a tough question.

Audience 5: You mentioned earlier that CRISPR is mostly very accurate, and how does it fail? Would this failing mean it’s sticking that section of DNA somewhere it shouldn’t? Or it just can’t find the piece of DNA it’s trying to untangle it proverbially gives out?

Jennifer Doudna: Yeah. Right. Thank you for that question, because it’s really important. It fails, or it induces, what we call off-target changes to DNA when it engages on a place in the genome that doesn’t maybe perfectly match the guide RNA sequence, and that does happen with some frequency. The frequency of that really turns out to depend greatly on the way these molecules are actually introduced into cells, the amount of the editor that’s in the cell, the time that it stays active in the cell and all of those sorts of things. And so it’s been a very active area of research over the last few years to investigate off-target editing, and how does it work, and how do we prevent it, and there have been a lot of advances, I would say, in the technology that make me think that today that’s not really a bottleneck going forward, even for clinical use.

It’s not to say that we ignore it, but we have to pay attention to the accuracy of the editor, but there are better and better ways of both monitoring that as well as modified forms of these proteins that are even more accurate. I think the other way to think about your question is what about … And this kind of gets back to this earlier question about unintended consequences. What about edits that are happening as we intend, but they lead to a genetic alteration that has an undesired or unintended outcome, right? So you’ve altered the gene that you intended to alter, but it has an unpredictable or undesired outcome, and that’s a lot harder to figure out how to test in controlled work.

Audience 6: Thank you for your presentation. I’m from a startup community, so I’d like to hear your view on how you see the responsibility and the load of the startups on the venture capital in the ecosystem. There’s a lot of money now coming into that space, so I want to see how you see its positive or negative trend.

Jennifer Doudna: Right. You’re touching on a very important point, and I didn’t get a chance to talk about it today, but there’s a tremendous interest in the biotech and investor communities in gene editing as a technology that will enable all sorts of commercial opportunities. And that’s on the one hand very exciting and I think will lead to important advances, especially in sort of the outcomes of this tool, but at the same time it does raise challenges, especially for things like conflicts of interest, right? Because people like me and many of my colleagues are involved in some of those companies, and so you could imagine conflicts arising between the research that we’re doing and the business opportunities or models of those companies. So I think it’s just something that we have to be very cognizant of and paying very close attention to. It starts with transparency about engagements we all have.

But I also think that… I want to point out that I think there’s very exciting ways of advancing technology that involve partnering between academics and companies. This is something I really didn’t know anything about until a few years ago. My work had never had any commercial implications whatsoever in the past, but I’ve had to kind of learn about this, and again, I’ve benefited from a lot of experts here at Cal who I’ve been able to talk to about different aspects of these kinds of partnerships.

But I think that there are times when there is research being done in academic labs that has potential commercially, but is going in a direction that really couldn’t be explored by an academic lab because we don’t have the resources, and frankly, we maybe don’t have the desire or the expertise to take the work in that kind of direction. So by partnering with companies, I think we can do things together that neither party would be able to do alone, so I think the challenge is to look for those opportunities and always maintaining the transparency necessary to try to avoid conflicts.

Audience 7: Hi. My question was about what you discussed earlier. You showed that there were mutations, the edits that He Jiankui made to the genome where human edits that had never before been seen in the human population. And I was sort of wondering how you deal with the consequences of that where, I mean, obviously they’ve been edited now, but these are human beings and they could live 30, 50, 100 years, and obviously the genome isn’t static and there’s often mutations. And so I was wondering, number one, how you deal with mutations in a genome that is different than what is in the normal population. And then also if those children decide to have their own children, you now have a lineage of genetically modified humans that we’ve introduced into the population, like how you deal with that going forward and how that affects sort of the whole human population.

Jennifer Doudna: Right. Well, so to take the second question first, I think it’s important to appreciate that introducing a trait like that into the whole human population would take a really long time, right? So I think that’s not going to happen, but you’re right that those children now could pass this trait on to their kids and it becomes part of their family lineage. So going forward, it will be essential, I think, to monitor these girls’ health as they mature and try to figure out, in your first question, how stable are these edits, and what impact does that genetic change to their DNA on their health. Not only in terms of their susceptibility to infection, because it’s a change that could affect the function of their immune cells, but also might affect other aspects of their health.

There’s some publications now and some papers out very recently that suggest that the gene that was edited in these girls, in addition to affecting their susceptibility to HIV infection, might also affect other aspects of neural function, and might in fact be in some way beneficial to their health. And so that will have to be assessed going forward, and I think that would have to be done, in my opinion, by a third-party group external to … It wouldn’t be appropriate for the monitoring to be done by the scientist that actually did the work, right? It would need to be done by a third party. Now, will that happen? It’s hard to say.

Audience 8: Thank you. I’d like to touch on eugenics for a minute, and given the really dark history in this state in particular, do you envision the government taking a harsh stance early on, or do you envision it being left open to the marketplace? How do you kind of envision that aspect of the technology moving forward?

Jennifer Doudna: Well, I guess I imagine that it’s likely to move forward analogous to the way that in vitro fertilization has unfolded, so I’m old enough to remember when my parents would sit at the dinner table at night and debate the morality of test tube babies, and talk about was it right for people to be conceived in a test tube, and it seemed really weird. But then over time, you know that we had family friends who benefited from IVF, and many other people as well, and Louise Brown grew up and she seemed to be fine. And so over time, in a very kind of grassroots way almost. People came to accept that technology, and I almost wonder if we’ll see a similar thing with human germline editing, that it’ll perhaps start to be used in some IVF clinics, I hope under much more stringent regulatory guidelines than has happened in this first instance.

If those uses result in perceived benefits to kids and to families, then you could imagine that will start to be more widely adopted. Now, does that mean that we’re entering into an era of eugenics? I don’t really see that likely to be happening. I think that it’s probably going to be more sporadically utilized, and I would hope that initial uses are limited to real medical need rather than what we might consider to be enhancements.

Audience 9: How close are we to kind of curing single-gene diseases, like Huntington’s that you were talking about, and how would you translate that from in the lab to human? And also, what are the difficulties both in the policy side and the scientific community since healthcare is very profit-driven?

Jennifer Doudna: I think your question is about how… You said, “How close are we to being able to correct a single-gene mutation?” Was that your question? We’re already there. I mean, it’s amazing, but we’re already there, so I can give you just a couple of fast examples. I mean, right now in animals, in mice, it’s been possible to introduce genetic changes that correct a disease of the liver. That’s been done in a couple of cases. Eric Olson at the University of Texas recently published data showing that in a dog model of Duchenne muscular dystrophy, you could actually introduce genetic changes that alleviated the phenotype of that disease, which it’s a crippling muscular degenerative disorder, which was really a profound sort of… He showed these results at a scientific conference a few months back, and I think everybody in the room was just kind of stunned.

But how do we go from where we are now with that kind of application in animals, and certainly in all kinds of stem cells and cells in the laboratory, how do we go from that to actually having a treatment that will be available and useful for curing patients? And this is where the expertise of many folks in the room goes far beyond what I know, but it’s certainly going to involve things like we have to figure out how to deliver gene editing molecules in the cells. That’s sort of the scientific and technical challenge, but then there’s the challenge of the cost of that kind of a treatment, and how affordable would that be. Who pays for it? Is it going to be covered by insurance, and how do we decide that? And then who gets access to it, right?

If these are, for example, patients that are afflicted with sickle cell disease, I think we’re on the verge of having a strategy that will actually be curative for sickle cell disease. That’s tremendous, but there’s 100,000 people in the US alone that are afflicted, and then there’s many, many people in Sub-Saharan Africa that are afflicted. And so how do we ensure that there’s sort of an equitable distribution of a technology like that, and potentially a cure? These are profound questions, and I think they have to be tackled. Again, there’s sort of no easy answers.

Audience 10: I had a question about food regulation. You just discussed how, basically, the removal of genes from food, food genomes, is not regulated by the US FDA. Why did they make that judgment? And do you think that the removal of a certain gene can have unintended consequences that they aren’t accounting for?

Jennifer Doudna: Right. My understanding of that decision by the US Department of Agriculture is that they basically look at genetic changes that are made to a plant, and they decided that if there’s no introduction of foreign DNA, that effectively, you could argue that genetic knockout is something that could happen naturally. You know, you could have plant breeders that could knock out a gene. It could take a really long time, but they could get there through natural … There could be a natural process towards that genetic knockout. Whereas a knock-in, where a knew sort of foreign gene, let’s say, that’s not been in that plant before is introduced. That’s much harder to imagine how that could happen naturally, so I think that was sort of the basis of making that decision.

And you might wonder, “Well, how come in Europe the decision went a different direction?” And I think it’s because in Europe they define genetic modification according to just the technology manipulation itself. If this plant was manipulated with some kind of a tool, like a gene editing tool, even if you ended up with exactly the same plant at the end of the experiment, it would still be called genetically modified because it went through that process of being exposed to the technology. Does that make sense? It’s just different ways of defining what we consider genetic modification.

But as you can see, these are all, in a way, very subjective kinds of decisions, and I think they’re really going to come down in many cases to what all of us as the consumers of those potential products really want. Do people want to have access to those plant products that are the product of genetic manipulation or not? And my personal feeling there is that if you think about how traditional plant breeding works, it involved mutagenizing plants and you get lots of random changes to DNA, and then you simply select for plants that have desired traits. Who knows what other genetic changes are coming along for the ride, and as you know, it results in things like roses that don’t smell nice anymore because those genes have been lost in the process of removing thorns, you know, things like that. I think we have to just, again, be very thoughtful about what kind of regulation we might advocate for given the realities of how the technology works.

Audience 11: Hi. Good evening. My name is Aidan Hill. I’m a former candidate for Berkeley City Council representing this area, so like many of the constituents here, I have concerns about the dual use applicability, as well as the bioweaponry available with CRISPR technology. But I’m curious, has there been any trials of CRISPR technology with 5G technology? And what are the circumstances of cellular radiation using this technology to enhance the genomic structure? Thank you.

Jennifer Doudna: Okay. I didn’t entirely understand the details of your question, but I think you’re generally asking about dual use of genome editing technology, which basically means the potential for a technology to be used both for the public good, but also for harm. I’ve had a lot of discussions about this with people. We’ve had a number of visits from government agencies that have come to Berkeley and talked with me and other folks, as well as our colleagues around the country about this question, and I feel that gene editing, it’s sort of no different than other technologies that have the potential to do good and bad. And they have to be carefully, for sure.

I think one of the challenges with gene editing, and hopefully you took this away from my talk, is that it’s widely available. It’s really easy for people to get ahold of it. It’s not something you can lock away in a box, and even if we wanted to get rid of it, and I think we don’t, but even if we wanted to say, “Well, we’re not going to let scientists use this anymore for certain kinds of things,” it’s going to be very, very hard to actually do that. I think more effective is going to be really just being very transparent about uses that are contemplated and getting the scientific community to really engage in thinking about how to work together to encourage a culture of responsible use. It’s not a perfect solution, but I think it’s a good start.

Audience 12: Thank you, and Dr. Doudna, thank you so much for all your work. My question is this: if you know the gene that is a cause of a particular disease, and specific context happens to be retinal degenerative disease, and you’re able to edit out the defective part of the gene, where does the healthy gene that you’re going to replace come from? If that’s an intelligent question. And then secondly, am I correct that the CRISPR has two aspects precluding the transfer, or the inheritance, of a gene that’s defective by editing it out, but also the ability to get the new corrected gene to express itself so that you might have some immediate effect in that person? Thank you very much.

Jennifer Doudna: Yeah. No, those are both really great questions. I showed this example of a piece of DNA being inserted into a genome in the process of repairing a break introduced by this CRISPR-Cas9 protein. Where does that DNA come from? It’s a great question. There’s two sources. One is from the cell itself, so you probably know that there are two alleles, two copies, of every gene in a diploid cell, and so you could imagine a scenario where one of those alleles is cut by CRISPR-Cas9, especially if it has a change in the sequence that allows specific recognition, and then you could have repair by the other allele, so that’s one possibility. And that’s actually been demonstrated in animals to be a pathway for DNA repair.

But in many cases, especially if we were going to use this kind of strategy clinically, scientists can actually introduce that DNA repair template into cells externally, so they can introduce it on a virus, for example. Or just some other kind of piece of DNA that gets introduced into cells where it provides the template for DNA repair, so that’s how that’s done. And then your other question was… Remind me, the second question.

And to answer your second question: Great question, because it really gets at this distinction between making heritable changes in the germline, where those changes just become part of the individual and can be passed on to the future children of that individual, but if we do the editing in somatic cells, then that means we’re making changes to DNA in a single individual and maybe just in one tissue of that individual. You could imagine someday being able to treat muscular dystrophy in patients that have that disease by just treating their muscle cells if you had a way to deliver gene editing into just those cells. And then you could actually, as was done in this dog model, you could actually turn on production of the normal protein that’s missing in those people and in these dogs and restore muscle function.

Audience 13: I was kind of wondering one. What kind of future do you see for CRISPR-Cas9 in just over-the-counter sort of cough and cold medicine? And I was wondering, what would happen if you tried to defend against mutations from gene editing by using more gene editing to put the genes back how they originally were?

Jennifer Doudna: Yeah. Thank you. Both of those, again, are really great questions, so how soon are we going to see over-the-counter gene editing? And I have two answers to that. One is that we already have that today if we’re not talking about editing people, right? Because you can actually … Scientists can go to a nonprofit organization called Addgene, and for very inexpensive, very low cost, they can get access to these gene editing molecules. And they can start doing experiments in their lab, so in that sense it’s sort of is over-the-counter. How soon will that be? You’re going to the store and you have a headache and you need to buy CRISPR-Cas9. No, not very soon for lots of reasons, and it’s probably a good thing.

And then your second question was… Remind me. Shout it out.

Audience 13: Would it be possible to counteract mutations from gene editing with more gene editing?

Jennifer Doudna: Yeah. I think the way I would answer that is I think what you’re asking is once you change the DNA in a cell, can you change it back? What do you do? And so there’s lots of interest in this right now in the scientific community. There’s lots of people that are thinking about that question, actually. How do we think about gene edits, and what if you wanted to turn off a gene editor that you’d put into cells and either… I don’t know about reversing those genetic changes. That might be harder, but certainly not allowing the gene editor to go on indefinitely, sort of modifying DNA and cells.

And so there’s a really interesting biological phenomenon. It turns out in nature, as I kind of talked about in the beginning of my talk, so these CRISPR enzymes, these proteins, arose as a bacterial adaptive immune system. They prevent viral infection in bugs. Well, you can imagine the viruses don’t like that very much, and so they fight back, and they actually make little proteins that inhibit the CRISPR enzymes, so they have inhibitors. We call these anti-CRISPRs, and so there’s kind of this natural kind of war going on between CRISPR proteins and then these anti-CRISPRs. And there’s lots of research happening right now to understand how those work, but also how you could actually use them in a protective way in cells to prevent undesirable genetic changes.

Audience 14: Hello. Thank you so much. I was wondering, earlier you mentioned that pigs are being genetically engineered to produce organs for organ donation, and mosquitoes are being genetically altered to either become extinct or become sterile in terms of spreading disease to humans. And I was just wondering where your thoughts on the implications of altering the environment to aid in the extension of human life expectancy.

Jennifer Doudna: Well, I think in both those examples, and especially in the case of a gene drive that could have big implications environmentally that could be hard to predict initially. I think we have to proceed with extreme caution, so I really favor careful evaluation under very defined laboratory settings before proceeding further. And right now, there are a number of studies going on in research labs to test, especially gene drives, and then there are some controlled studies that are planned in isolated environmental settings just to kind of a get a sense of how effective these will really be in a natural population. That’s something that really hasn’t been explored yet, but I think the key is proceeding carefully and with a lot of thought behind each step that’s taken.

Host: Please join me in thanking Professor Doudna.