Tag Archives: CRISPR/Cas9

Could CRISPR (clustered regularly interspaced short palindromic repeats) be weaponized?

On the occasion of an American team’s recent publication of research where they edited the germline (embryos), I produced a three-part series about CRISPR (clustered regularly interspaced short palindromic repeats), sometimes referred to as CRISPR/Cas9, (links offered at end of this post).

Somewhere in my series, there’s a quote about how CRISPR could be used as a ‘weapon of mass destruction’ and it seems this has been a hot topic for the last year or so as James Revill, research fellow at the University of Sussex, references in his August 31, 2017 essay on theconversation.com (h/t phys.org August 31, 2017 news item), Note: Links have been removed,

The gene editing technique CRISPR has been in the limelight after scientists reported they had used it to safely remove disease in human embryos for the first time. This follows a “CRISPR craze” over the last couple of years, with the number of academic publications on the topic growing steadily.

There are good reasons for the widespread attention to CRISPR. The technique allows scientists to “cut and paste” DNA more easily than in the past. It is being applied to a number of different peaceful areas, ranging from cancer therapies to the control of disease carrying insects.

Some of these applications – such as the engineering of mosquitoes to resist the parasite that causes malaria – effectively involve tinkering with ecosystems. CRISPR has therefore generated a number of ethical and safety concerns. Some also worry that applications being explored by defence organisations that involve “responsible innovation in gene editing” may send worrying signals to other states.

Concerns are also mounting that gene editing could be used in the development of biological weapons. In 2016, Bill Gates remarked that “the next epidemic could originate on the computer screen of a terrorist intent on using genetic engineering to create a synthetic version of the smallpox virus”. More recently, in July 2017, John Sotos, of Intel Health & Life Sciences, stated that gene editing research could “open up the potential for bioweapons of unimaginable destructive potential”.

An annual worldwide threat assessment report of the US intelligence community in February 2016 argued that the broad availability and low cost of the basic ingredients of technologies like CRISPR makes it particularly concerning.

A Feb. 11, 2016 news item on sciencemagazine.org offers a précis of some of the reactions while a February 9, 2016 article by Antonio Regalado for the Massachusetts Institute of Technology’s MIT Technology Review delves into the matter more deeply,

Genome editing is a weapon of mass destruction.

That’s according to James Clapper, [former] U.S. director of national intelligence, who on Tuesday, in the annual worldwide threat assessment report of the U.S. intelligence community, added gene editing to a list of threats posed by “weapons of mass destruction and proliferation.”

Gene editing refers to several novel ways to alter the DNA inside living cells. The most popular method, CRISPR, has been revolutionizing scientific research, leading to novel animals and crops, and is likely to power a new generation of gene treatments for serious diseases (see “Everything You Need to Know About CRISPR’s Monster Year”).

It is gene editing’s relative ease of use that worries the U.S. intelligence community, according to the assessment. “Given the broad distribution, low cost, and accelerated pace of development of this dual-use technology, its deliberate or unintentional misuse might lead to far-reaching economic and national security implications,” the report said.

The choice by the U.S. spy chief to call out gene editing as a potential weapon of mass destruction, or WMD, surprised some experts. It was the only biotechnology appearing in a tally of six more conventional threats, like North Korea’s suspected nuclear detonation on January 6 [2016], Syria’s undeclared chemical weapons, and new Russian cruise missiles that might violate an international treaty.

The report is an unclassified version of the “collective insights” of the Central Intelligence Agency, the National Security Agency, and half a dozen other U.S. spy and fact-gathering operations.

Although the report doesn’t mention CRISPR by name, Clapper clearly had the newest and the most versatile of the gene-editing systems in mind. The CRISPR technique’s low cost and relative ease of use—the basic ingredients can be bought online for $60—seems to have spooked intelligence agencies.

….

However, one has to be careful with the hype surrounding new technologies and, at present, the security implications of CRISPR are probably modest. There are easier, cruder methods of creating terror. CRISPR would only get aspiring biological terrorists so far. Other steps, such as growing and disseminating biological weapons agents, would typically be required for it to become an effective weapon. This would require additional skills and places CRISPR-based biological weapons beyond the reach of most terrorist groups. At least for the time being.

A July 5, 2016 opinion piece by Malcolm Dando for Nature argues for greater safeguards,

In Geneva next month [August 2016], officials will discuss updates to the global treaty that outlaws the use of biological weapons. The 1972 Biological Weapons Convention (BWC) was the first agreement to ban an entire class of weapons, and it remains a crucial instrument to stop scientific research on viruses, bacteria and toxins from being diverted into military programmes.

The BWC is the best route to ensure that nations take the biological-weapons threat seriously. Most countries have struggled to develop and introduce strong and effective national programmes — witness the difficulty the United States had in agreeing what oversight system should be applied to gain-of-function experiments that created more- dangerous lab-grown versions of common pathogens.

As scientific work advances — the CRISPR gene-editing system has been flagged as the latest example of possible dual-use technology — this treaty needs to be regularly updated. This is especially important because it has no formal verification system. Proposals for declarations, monitoring visits and inspections were vetoed by the United States in 2001, on the grounds that such verification threatened national security and confidential business information.

Even so, issues such as the possible dual-use threat from gene-editing systems will not be easily resolved. But we have to try. Without the involvement of the BWC, codes of conduct and oversight systems set up at national level are unlikely to be effective. The stakes are high, and after years of fumbling, we need strong international action to monitor and assess the threats from the new age of biological techniques.

Revill notes the latest BWC agreement and suggests future directions,

This convention is imperfect and lacks a way to ensure that states are compliant. Moreover, it has not been adequately “tended to” by its member states recently, with the last major meeting unable to agree a further programme of work. Yet it remains the cornerstone of an international regime against the hostile use of biology. All 178 state parties declared in December of 2016 their continued determination “to exclude completely the possibility of the use of (biological) weapons, and their conviction that such use would be repugnant to the conscience of humankind”.

These states therefore need to address the hostile potential of CRISPR. Moreover, they need to do so collectively. Unilateral national measures, such as reasonable biological security procedures, are important. However, preventing the hostile exploitation of CRISPR is not something that can be achieved by any single state acting alone.

As such, when states party to the convention meet later this year, it will be important to agree to a more systematic and regular review of science and technology. Such reviews can help with identifying and managing the security risks of technologies such as CRISPR, as well as allowing an international exchange of information on some of the potential benefits of such technologies.

Most states supported the principle of enhanced reviews of science and technology under the convention at the last major meeting. But they now need to seize the opportunity and agree on the practicalities of such reviews in order to prevent the convention being left behind by developments in science and technology.

Experts (military, intelligence, medical, etc.) are not the only ones concerned about CRISPR according to a February 11, 2016 article by Sharon Begley for statnews.com (Note: A link has been removed),

Most Americans oppose using powerful new technology to alter the genes of unborn babies, according to a new poll — even to prevent serious inherited diseases.

They expressed the strongest disapproval for editing genes to create “designer babies” with enhanced intelligence or looks.

But the poll, conducted by STAT and Harvard T.H. Chan School of Public Health, found that people have mixed, and apparently not firm, views on emerging genetic techniques. US adults are almost evenly split on whether the federal government should fund research on editing genes before birth to keep children from developing diseases such as cystic fibrosis or Huntington’s disease.

“They’re not against scientists trying to improve [genome-editing] technologies,” said Robert Blendon, professor of health policy and political analysis at Harvard’s Chan School, perhaps because they recognize that one day there might be a compelling reason to use such technologies. An unexpected event, such as scientists “eliminating a terrible disease” that a child would have otherwise inherited, “could change people’s views in the years ahead,” Blendon said.

But for now, he added, “people are concerned about editing the genes of those who are yet unborn.”

A majority, however, wants government regulators to approve gene therapy to treat diseases in children and adults.

The STAT-Harvard poll comes as scientists and policy makers confront the ethical, social, and legal implications of these revolutionary tools for changing DNA. Thanks to a technique called CRISPR-Cas9, scientists can easily, and with increasing precision, modify genes through the genetic analog of a computer’s “find and replace” function.

I find it surprising that there’s resistance to removing diseases found in the germline (embryos). When they were doing public consultations on nanotechnology, the one area where people tended to be quite open to research was health and medicine. Where food was concerned however, people had far more concerns.

If you’re interested in the STAT-Harvard poll, you can find it here. As for James Revill, he has written a more substantive version of this essay as a paper, which is available here.

On a semi-related note, I found STAT (statnews.com) to be a quite interesting and accessibly written online health science journal. Here’s more from the About Us page (Note: A link has been removed),

What’s STAT all about?
STAT is a national publication focused on finding and telling compelling stories about health, medicine, and scientific discovery. We produce daily news, investigative articles, and narrative projects in addition to multimedia features. We tell our stories from the places that matter to our readers — research labs, hospitals, executive suites, and political campaigns.

Why did you call it STAT?
In medical parlance, “stat” means important and urgent, and that’s what we’re all about — quickly and smartly delivering good stories. Read more about the origins of our name here.

Who’s behind the new publication?
STAT is produced by Boston Globe Media. Our headquarters is located in Boston but we have bureaus in Washington, New York, Cleveland, Atlanta, San Francisco, and Los Angeles. It was started by John Henry, the owner of Boston Globe Media and the principal owner of the Boston Red Sox. Rick Berke is executive editor.

So is STAT part of The Boston Globe?
They’re distinct properties but the two share content and complement one another.

Is it free?
Much of STAT is free. We also offer STAT Plus, a premium subscription plan that includes exclusive reporting about the pharmaceutical and biotech industries as well as other benefits. Learn more about it here.

Who’s working for STAT?
Some of the best-sourced science, health, and biotech journalists in the country, as well as motion graphics artists and data visualization specialists. Our team includes talented writers, editors, and producers capable of the kind of explanatory journalism that complicated science issues sometimes demand.

Who’s your audience?
You. Even if you don’t work in science, have never stepped foot in a hospital, or hated high school biology, we’ve got something for you. And for the lab scientists, health professionals, business leaders, and policy makers, we think you’ll find coverage here that interests you, too. The world of health, science, and medicine is booming and yielding fascinating stories. We explore how they affect us all.

….

As promised, here are the links to my three-part series on CRISPR,

Part 1 opens the series with a basic description of CRISPR and the germline research that occasioned the series along with some of the other (non-weapon) ethical issues and patent disputes that are arising from this new technology. CRISPR and editing the germline in the US (part 1 of 3): In the beginning

Part 2 covers three critical responses to the reporting and between them describe the technology in more detail and the possibility of ‘designer babies’.  CRISPR and editing the germline in the US (part 2 of 3): ‘designer babies’?

Part 3 is all about public discussion or, rather, the lack of and need for according to a couple of social scientists. Informally, there is some discussion via pop culture and Joelle Renstrom notes although she is focused on the larger issues touched on by the television series, Orphan Black and as I touch on in my final comments. CRISPR and editing the germline in the US (part 3 of 3): public discussions and pop culture

Finally, I hope to stumble across studies from other countries about how they are responding to the possibilities presented by CRISPR/Cas9 so that I can offer a more global perspective than this largely US perspective. At the very least, it would be interesting to find it if there differences.

CRISPR corn to come to market in 2020

It seems most of the recent excitement around CRISPR/CAS9 (clustered regularly interspaced short palindromic repeats) has focused on germline editing, specifically human embryos. Most people don’t realize that the first ‘CRISPR’ product is slated to enter the US market in 2020. A June 14, 2017 American Chemical Society news release (also on EurekAlert) provides a preview,

The gene-editing technique known as CRISPR/Cas9 made a huge splash in the news when it was initially announced. But the first commercial product, expected around 2020, could make it to the market without much fanfare: It’s a waxy corn destined to contribute to paper glue and food thickeners. The cover story of Chemical & Engineering News (C&EN), the weekly newsmagazine of the American Chemical Society, explores what else is in the works.

Melody M. Bomgardner, a senior editor at C&EN [Chemical & Engineering News], notes that compared to traditional biotechnology, CRISPR allows scientists to add and remove specific genes from organisms with greater speed, precision and oftentimes, at a lower cost. Among other things, it could potentially lead to higher quality cotton, non-browning mushrooms, drought-resistant corn and — finally — tasty, grocery store tomatoes.

Some hurdles remain, however, before more CRISPR products become available. Regulators are assessing how they should approach crops modified with the technique, which often (though not always) splices genes into a plant from within the species rather than introducing a foreign gene. And scientists still don’t understand all the genes in any given crop, much less know which ones might be good candidates for editing. Luckily, researchers can use CRISPR to find out.

Melody M. Bomgardner’s June 12, 2017 article for C&EN describes in detail how CRISPR could significantly change agriculture (Note: Links have been removed),

When the seed firm DuPont Pioneer first announced the new corn in early 2016, few people paid attention. Pharmaceutical companies using CRISPR for new drugs got the headlines instead.

But people should notice DuPont’s waxy corn because using CRISPR—an acronym for clustered regularly interspaced short palindromic repeats—to delete or alter traits in plants is changing the world of plant breeding, scientists say. Moreover, the technique’s application in agriculture is likely to reach the public years before CRISPR-aided drugs hit the market.

Until CRISPR tools were developed, the process of finding useful traits and getting them into reliable, productive plants took many years. It involved a lot of steps and was plagued by randomness.

“Now, because of basic research in the lab and in the field, we can go straight after the traits we want,” says Zachary Lippman, professor of biological sciences at Cold Spring Harbor Laboratory. CRISPR has been transformative, Lippman says. “It’s basically a freight train that’s not going to stop.”

Proponents hope consumers will embrace gene-edited crops in a way that they did not accept genetically engineered ones, especially because they needn’t involve the introduction of genes from other species—a process that gave rise to the specter of Frankenfood.

But it’s not clear how consumers will react or if gene editing will result in traits that consumers value. And the potential commercial uses of CRISPR may narrow if agriculture agencies in the U.S. and Europe decide to regulate gene-edited crops in the same way they do genetically engineered crops.

DuPont Pioneer expects the U.S. to treat its gene-edited waxy corn like a conventional crop because it does not contain any foreign genes, according to Neal Gutterson, the company’s vice president of R&D. In fact, the waxy trait already exists in some corn varieties. It gives the kernels a starch content of more than 97% amylopectin, compared with 75% amylopectin in regular feed corn. The rest of the kernel is amylose. Amylopectin is more soluble than amylose, making starch from waxy corn a better choice for paper adhesives and food thickeners.

Like most of today’s crops, DuPont’s current waxy corn varieties are the result of decades of effort by plant breeders using conventional breeding techniques.

Breeders identify new traits by examining unusual, or mutant, plants. Over many generations of breeding, they work to get a desired trait into high-performing (elite) varieties that lack the trait. They begin with a first-generation cross, or hybrid, of a mutant and an elite plant and then breed several generations of hybrids with the elite parent in a process called backcrossing. They aim to achieve a plant that best approximates the elite version with the new trait.

But it’s tough to grab only the desired trait from a mutant and make a clean getaway. DuPont’s plant scientists found that the waxy trait came with some genetic baggage; even after backcrossing, the waxy corn plant did not offer the same yield as elite versions without the trait. The disappointing outcome is common enough that it has its own term: yield drag.

Because the waxy trait is native to certain corn plants, DuPont did not have to rely on the genetic engineering techniques that breeders have used to make herbicide-tolerant and insect-resistant corn plants. Those commonly planted crops contain DNA from other species.

In addition to giving some consumers pause, that process does not precisely place the DNA into the host plant. So researchers must raise hundreds or thousands of modified plants to find the best ones with the desired trait and work to get that trait into each elite variety. Finally, plants modified with traditional genetic engineering need regulatory approval in the U.S. and other countries before they can be marketed.

Instead, DuPont plant scientists used CRISPR to zero in on, and partially knock out, a gene for an enzyme that produces amylose. By editing the gene directly, they created a waxy version of the elite corn without yield drag or foreign DNA.

Plant scientists who adopt gene editing may still need to breed, measure, and observe because traits might not work well together or bring a meaningful benefit. “It’s not a panacea,” Lippman says, “but it is one of the most powerful tools to come around, ever.”

It’s an interesting piece which answers the question of why tomatoes from the grocery store don’t taste good.

CRISPR and editing the germline in the US (part 3 of 3): public discussions and pop culture

After giving a basic explanation of the technology and some of the controversies in part 1 and offering more detail about the technology and about the possibility of designer babies in part 2; this part covers public discussion, a call for one and the suggestion that one is taking place in popular culture.

But a discussion does need to happen

In a move that is either an exquisite coincidence or has been carefully orchestrated (I vote for the latter), researchers from the University of Wisconsin-Madison have released a study about attitudes in the US to human genome editing. From an Aug. 11, 2017 University of Wisconsin-Madison news release (also on EurekAllert),

In early August 2017, an international team of scientists announced they had successfully edited the DNA of human embryos. As people process the political, moral and regulatory issues of the technology — which nudges us closer to nonfiction than science fiction — researchers at the University of Wisconsin-Madison and Temple University show the time is now to involve the American public in discussions about human genome editing.

In a study published Aug. 11 in the journal Science, the researchers assessed what people in the United States think about the uses of human genome editing and how their attitudes may drive public discussion. They found a public divided on its uses but united in the importance of moving conversations forward.

“There are several pathways we can go down with gene editing,” says UW-Madison’s Dietram Scheufele, lead author of the study and member of a National Academy of Sciences committee that compiled a report focused on human gene editing earlier this year. “Our study takes an exhaustive look at all of those possible pathways forward and asks where the public stands on each one of them.”

Compared to previous studies on public attitudes about the technology, the new study takes a more nuanced approach, examining public opinion about the use of gene editing for disease therapy versus for human enhancement, and about editing that becomes hereditary versus editing that does not.

The research team, which included Scheufele and Dominique Brossard — both professors of life sciences communication — along with Michael Xenos, professor of communication arts, first surveyed study participants about the use of editing to treat disease (therapy) versus for enhancement (creating so-called “designer babies”). While about two-thirds of respondents expressed at least some support for therapeutic editing, only one-third expressed support for using the technology for enhancement.

Diving even deeper, researchers looked into public attitudes about gene editing on specific cell types — somatic or germline — either for therapy or enhancement. Somatic cells are non-reproductive, so edits made in those cells do not affect future generations. Germline cells, however, are heritable, and changes made in these cells would be passed on to children.

Public support of therapeutic editing was high both in cells that would be inherited and those that would not, with 65 percent of respondents supporting therapy in germline cells and 64 percent supporting therapy in somatic cells. When considering enhancement editing, however, support depended more upon whether the changes would affect future generations. Only 26 percent of people surveyed supported enhancement editing in heritable germline cells and 39 percent supported enhancement of somatic cells that would not be passed on to children.

“A majority of people are saying that germline enhancement is where the technology crosses that invisible line and becomes unacceptable,” says Scheufele. “When it comes to therapy, the public is more open, and that may partly be reflective of how severe some of those genetically inherited diseases are. The potential treatments for those diseases are something the public at least is willing to consider.”

Beyond questions of support, researchers also wanted to understand what was driving public opinions. They found that two factors were related to respondents’ attitudes toward gene editing as well as their attitudes toward the public’s role in its emergence: the level of religious guidance in their lives, and factual knowledge about the technology.

Those with a high level of religious guidance in their daily lives had lower support for human genome editing than those with low religious guidance. Additionally, those with high knowledge of the technology were more supportive of it than those with less knowledge.

While respondents with high religious guidance and those with high knowledge differed on their support for the technology, both groups highly supported public engagement in its development and use. These results suggest broad agreement that the public should be involved in questions of political, regulatory and moral aspects of human genome editing.

“The public may be split along lines of religiosity or knowledge with regard to what they think about the technology and scientific community, but they are united in the idea that this is an issue that requires public involvement,” says Scheufele. “Our findings show very nicely that the public is ready for these discussions and that the time to have the discussions is now, before the science is fully ready and while we have time to carefully think through different options regarding how we want to move forward.”

Here’s a  link to and a citation for the paper,

U.S. attitudes on human genome editing by Dietram A. Scheufele, Michael A. Xenos, Emily L. Howell, Kathleen M. Rose, Dominique Brossard1, and Bruce W. Hardy. Science 11 Aug 2017: Vol. 357, Issue 6351, pp. 553-554 DOI: 10.1126/science.aan3708

This paper is behind a paywall.

A couple of final comments

Briefly, I notice that there’s no mention of the ethics of patenting this technology in the news release about the study.

Moving on, it seems surprising that the first team to engage in germline editing in the US is in Oregon; I would have expected the work to come from Massachusetts, California, or Illinois where a lot of bleeding edge medical research is performed. However, given the dearth of financial support from federal funding institutions, it seems likely that only an outsider would dare to engage i the research. Given the timing, Mitalipov’s work was already well underway before the recent about-face from the US National Academy of Sciences (Note: Kaiser’s Feb. 14, 2017 article does note that for some the recent recommendations do not represent any change).

As for discussion on issues such as editing of the germline, I’ve often noted here that popular culture (including advertising with the science fiction and other dramas laid in various media) often provides an informal forum for discussion. Joelle Renstrom in an Aug. 13, 2017 article for slate.com writes that Orphan Black (a BBC America series featuring clones) opened up a series of questions about science and ethics in the guise of a thriller about clones. She offers a précis of the first four seasons (Note: A link has been removed),

If you stopped watching a few seasons back, here’s a brief synopsis of how the mysteries wrap up. Neolution, an organization that seeks to control human evolution through genetic modification, began Project Leda, the cloning program, for two primary reasons: to see whether they could and to experiment with mutations that might allow people (i.e., themselves) to live longer. Neolution partnered with biotech companies such as Dyad, using its big pharma reach and deep pockets to harvest people’s genetic information and to conduct individual and germline (that is, genetic alterations passed down through generations) experiments, including infertility treatments that result in horrifying birth defects and body modification, such as tail-growing.

She then provides the article’s thesis (Note: Links have been removed),

Orphan Black demonstrates Carl Sagan’s warning of a time when “awesome technological powers are in the hands of a very few.” Neolutionists do whatever they want, pausing only to consider whether they’re missing an opportunity to exploit. Their hubris is straight out of Victor Frankenstein’s playbook. Frankenstein wonders whether he ought to first reanimate something “of simpler organisation” than a human, but starting small means waiting for glory. Orphan Black’s evil scientists embody this belief: if they’re going to play God, then they’ll control not just their own destinies, but the clones’ and, ultimately, all of humanity’s. Any sacrifices along the way are for the greater good—reasoning that culminates in Westmoreland’s eugenics fantasy to genetically sterilize 99 percent of the population he doesn’t enhance.

Orphan Black uses sci-fi tropes to explore real-world plausibility. Neolution shares similarities with transhumanism, the belief that humans should use science and technology to take control of their own evolution. While some transhumanists dabble in body modifications, such as microchip implants or night-vision eye drops, others seek to end suffering by curing human illness and aging. But even these goals can be seen as selfish, as access to disease-eradicating or life-extending technologies would be limited to the wealthy. Westmoreland’s goal to “sell Neolution to the 1 percent” seems frighteningly plausible—transhumanists, who statistically tend to be white, well-educated, and male, and their associated organizations raise and spend massive sums of money to help fulfill their goals. …

On Orphan Black, denial of choice is tantamount to imprisonment. That the clones have to earn autonomy underscores the need for ethics in science, especially when it comes to genetics. The show’s message here is timely given the rise of gene-editing techniques such as CRISPR. Recently, the National Academy of Sciences gave germline gene editing the green light, just one year after academy scientists from around the world argued it would be “irresponsible to proceed” without further exploring the implications. Scientists in the United Kingdom and China have already begun human genetic engineering and American scientists recently genetically engineered a human embryo for the first time. The possibility of Project Leda isn’t farfetched. Orphan Black warns us that money, power, and fear of death can corrupt both people and science. Once that happens, loss of humanity—of both the scientists and the subjects—is inevitable.

In Carl Sagan’s dark vision of the future, “people have lost the ability to set their own agendas or knowledgeably question those in authority.” This describes the plight of the clones at the outset of Orphan Black, but as the series continues, they challenge this paradigm by approaching science and scientists with skepticism, ingenuity, and grit. …

I hope there are discussions such as those Scheufele and Brossard are advocating but it might be worth considering that there is already some discussion underway, as informal as it is.

-30-

Part 1: CRISPR and editing the germline in the US (part 1 of 3): In the beginning

Part 2: CRISPR and editing the germline in the US (part 2 of 3): ‘designer babies’?

CRISPR and editing the germline in the US (part 2 of 3): ‘designer babies’?

Having included an explanation of CRISPR-CAS9 technology along with the news about the first US team to edit the germline and bits and pieces about ethics and a patent fight (part 1), this part hones in on the details of the work and worries about ‘designer babies’.

The interest flurry

I found three articles addressing the research and all three concur that despite some of the early reporting, this is not the beginning of a ‘designer baby’ generation.

First up was Nick Thieme in a July 28, 2017 article for Slate,

MIT Technology Review reported Thursday that a team of researchers from Portland, Oregon were the first team of U.S.-based scientists to successfully create a genetically modified human embryo. The researchers, led by Shoukhrat Mitalipov of Oregon Health and Science University, changed the DNA of—in MIT Technology Review’s words—“many tens” of genetically-diseased embryos by injecting the host egg with CRISPR, a DNA-based gene editing tool first discovered in bacteria, at the time of fertilization. CRISPR-Cas9, as the full editing system is called, allows scientists to change genes accurately and efficiently. As has happened with research elsewhere, the CRISPR-edited embryos weren’t implanted—they were kept sustained for only a couple of days.

In addition to being the first American team to complete this feat, the researchers also improved upon the work of the three Chinese research teams that beat them to editing embryos with CRISPR: Mitalipov’s team increased the proportion of embryonic cells that received the intended genetic changes, addressing an issue called “mosaicism,” which is when an embryo is comprised of cells with different genetic makeups. Increasing that proportion is essential to CRISPR work in eliminating inherited diseases, to ensure that the CRISPR therapy has the intended result. The Oregon team also reduced the number of genetic errors introduced by CRISPR, reducing the likelihood that a patient would develop cancer elsewhere in the body.

Separate from the scientific advancements, it’s a big deal that this work happened in a country with such intense politicization of embryo research. …

But there are a great number of obstacles between the current research and the future of genetically editing all children to be 12-foot-tall Einsteins.

Ed Yong in an Aug. 2, 2017 article for The Atlantic offered a comprehensive overview of the research and its implications (unusually for Yong, there seems to be mildly condescending note but it’s worth ignoring for the wealth of information in the article; Note: Links have been removed),

… the full details of the experiment, which are released today, show that the study is scientifically important but much less of a social inflection point than has been suggested. “This has been widely reported as the dawn of the era of the designer baby, making it probably the fifth or sixth time people have reported that dawn,” says Alta Charo, an expert on law and bioethics at the University of Wisconsin-Madison. “And it’s not.”

Given the persistent confusion around CRISPR and its implications, I’ve laid out exactly what the team did, and what it means.

Who did the experiments?

Shoukhrat Mitalipov is a Kazakhstani-born cell biologist with a history of breakthroughs—and controversy—in the stem cell field. He was the scientist to clone monkeys. He was the first to create human embryos by cloning adult cells—a move that could provide patients with an easy supply of personalized stem cells. He also pioneered a technique for creating embryos with genetic material from three biological parents, as a way of preventing a group of debilitating inherited diseases.

Although MIT Tech Review name-checked Mitalipov alone, the paper splits credit for the research between five collaborating teams—four based in the United States, and one in South Korea.

What did they actually do?

The project effectively began with an elevator conversation between Mitalipov and his colleague Sanjiv Kaul. Mitalipov explained that he wanted to use CRISPR to correct a disease-causing gene in human embryos, and was trying to figure out which disease to focus on. Kaul, a cardiologist, told him about hypertrophic cardiomyopathy (HCM)—an inherited heart disease that’s commonly caused by mutations in a gene called MYBPC3. HCM is surprisingly common, affecting 1 in 500 adults. Many of them lead normal lives, but in some, the walls of their hearts can thicken and suddenly fail. For that reason, HCM is the commonest cause of sudden death in athletes. “There really is no treatment,” says Kaul. “A number of drugs are being evaluated but they are all experimental,” and they merely treat the symptoms. The team wanted to prevent HCM entirely by removing the underlying mutation.

They collected sperm from a man with HCM and used CRISPR to change his mutant gene into its normal healthy version, while simultaneously using the sperm to fertilize eggs that had been donated by female volunteers. In this way, they created embryos that were completely free of the mutation. The procedure was effective, and avoided some of the critical problems that have plagued past attempts to use CRISPR in human embryos.

Wait, other human embryos have been edited before?

There have been three attempts in China. The first two—in 2015 and 2016—used non-viable embryos that could never have resulted in a live birth. The third—announced this March—was the first to use viable embryos that could theoretically have been implanted in a womb. All of these studies showed that CRISPR gene-editing, for all its hype, is still in its infancy.

The editing was imprecise. CRISPR is heralded for its precision, allowing scientists to edit particular genes of choice. But in practice, some of the Chinese researchers found worrying levels of off-target mutations, where CRISPR mistakenly cut other parts of the genome.

The editing was inefficient. The first Chinese team only managed to successfully edit a disease gene in 4 out of 86 embryos, and the second team fared even worse.

The editing was incomplete. Even in the successful cases, each embryo had a mix of modified and unmodified cells. This pattern, known as mosaicism, poses serious safety problems if gene-editing were ever to be used in practice. Doctors could end up implanting women with embryos that they thought were free of a disease-causing mutation, but were only partially free. The resulting person would still have many tissues and organs that carry those mutations, and might go on to develop symptoms.

What did the American team do differently?

The Chinese teams all used CRISPR to edit embryos at early stages of their development. By contrast, the Oregon researchers delivered the CRISPR components at the earliest possible point—minutes before fertilization. That neatly avoids the problem of mosaicism by ensuring that an embryo is edited from the very moment it is created. The team did this with 54 embryos and successfully edited the mutant MYBPC3 gene in 72 percent of them. In the other 28 percent, the editing didn’t work—a high failure rate, but far lower than in previous attempts. Better still, the team found no evidence of off-target mutations.

This is a big deal. Many scientists assumed that they’d have to do something more convoluted to avoid mosaicism. They’d have to collect a patient’s cells, which they’d revert into stem cells, which they’d use to make sperm or eggs, which they’d edit using CRISPR. “That’s a lot of extra steps, with more risks,” says Alta Charo. “If it’s possible to edit the embryo itself, that’s a real advance.” Perhaps for that reason, this is the first study to edit human embryos that was published in a top-tier scientific journal—Nature, which rejected some of the earlier Chinese papers.

Is this kind of research even legal?

Yes. In Western Europe, 15 countries out of 22 ban any attempts to change the human germ line—a term referring to sperm, eggs, and other cells that can transmit genetic information to future generations. No such stance exists in the United States but Congress has banned the Food and Drug Administration from considering research applications that make such modifications. Separately, federal agencies like the National Institutes of Health are banned from funding research that ultimately destroys human embryos. But the Oregon team used non-federal money from their institutions, and donations from several small non-profits. No taxpayer money went into their work. [emphasis mine]

Why would you want to edit embryos at all?

Partly to learn more about ourselves. By using CRISPR to manipulate the genes of embryos, scientists can learn more about the earliest stages of human development, and about problems like infertility and miscarriages. That’s why biologist Kathy Niakan from the Crick Institute in London recently secured a license from a British regulator to use CRISPR on human embryos.

Isn’t this a slippery slope toward making designer babies?

In terms of avoiding genetic diseases, it’s not conceptually different from PGD, which is already widely used. The bigger worry is that gene-editing could be used to make people stronger, smarter, or taller, paving the way for a new eugenics, and widening the already substantial gaps between the wealthy and poor. But many geneticists believe that such a future is fundamentally unlikely because complex traits like height and intelligence are the work of hundreds or thousands of genes, each of which have a tiny effect. The prospect of editing them all is implausible. And since genes are so thoroughly interconnected, it may be impossible to edit one particular trait without also affecting many others.

“There’s the worry that this could be used for enhancement, so society has to draw a line,” says Mitalipov. “But this is pretty complex technology and it wouldn’t be hard to regulate it.”

Does this discovery have any social importance at all?

“It’s not so much about designer babies as it is about geographical location,” says Charo. “It’s happening in the United States, and everything here around embryo research has high sensitivity.” She and others worry that the early report about the study, before the actual details were available for scrutiny, could lead to unnecessary panic. “Panic reactions often lead to panic-driven policy … which is usually bad policy,” wrote Greely [bioethicist Hank Greely].

As I understand it, despite the change in stance, there is no federal funding available for the research performed by Mitalipov and his team.

Finally, University College London (UCL) scientists Joyce Harper and Helen O’Neill wrote about CRISPR, the Oregon team’s work, and the possibilities in an Aug. 3, 2017 essay for The Conversation (Note: Links have been removed),

The genome editing tool used, CRISPR-Cas9, has transformed the field of biology in the short time since its discovery in that it not only promises, but delivers. CRISPR has surpassed all previous efforts to engineer cells and alter genomes at a fraction of the time and cost.

The technology, which works like molecular scissors to cut and paste DNA, is a natural defence system that bacteria use to fend off harmful infections. This system has the ability to recognise invading virus DNA, cut it and integrate this cut sequence into its own genome – allowing the bacterium to render itself immune to future infections of viruses with similar DNA. It is this ability to recognise and cut DNA that has allowed scientists to use it to target and edit specific DNA regions.

When this technology is applied to “germ cells” – the sperm and eggs – or embryos, it changes the germline. That means that any alterations made would be permanent and passed down to future generations. This makes it more ethically complex, but there are strict regulations around human germline genome editing, which is predominantly illegal. The UK received a licence in 2016 to carry out CRISPR on human embryos for research into early development. But edited embryos are not allowed to be inserted into the uterus and develop into a fetus in any country.

Germline genome editing came into the global spotlight when Chinese scientists announced in 2015 that they had used CRISPR to edit non-viable human embryos – cells that could never result in a live birth. They did this to modify the gene responsible for the blood disorder β-thalassaemia. While it was met with some success, it received a lot of criticism because of the premature use of this technology in human embryos. The results showed a high number of potentially dangerous, off-target mutations created in the procedure.

Impressive results

The new study, published in Nature, is different because it deals with viable human embryos and shows that the genome editing can be carried out safely – without creating harmful mutations. The team used CRISPR to correct a mutation in the gene MYBPC3, which accounts for approximately 40% of the myocardial disease hypertrophic cardiomyopathy. This is a dominant disease, so an affected individual only needs one abnormal copy of the gene to be affected.

The researchers used sperm from a patient carrying one copy of the MYBPC3 mutation to create 54 embryos. They edited them using CRISPR-Cas9 to correct the mutation. Without genome editing, approximately 50% of the embryos would carry the patients’ normal gene and 50% would carry his abnormal gene.

After genome editing, the aim would be for 100% of embryos to be normal. In the first round of the experiments, they found that 66.7% of embryos – 36 out of 54 – were normal after being injected with CRIPSR. Of the remaining 18 embryos, five had remained unchanged, suggesting editing had not worked. In 13 embryos, only a portion of cells had been edited.

The level of efficiency is affected by the type of CRISPR machinery used and, critically, the timing in which it is put into the embryo. The researchers therefore also tried injecting the sperm and the CRISPR-Cas9 complex into the egg at the same time, which resulted in more promising results. This was done for 75 mature donated human eggs using a common IVF technique called intracytoplasmic sperm injection. This time, impressively, 72.4% of embryos were normal as a result. The approach also lowered the number of embryos containing a mixture of edited and unedited cells (these embryos are called mosaics).

Finally, the team injected a further 22 embryos which were grown into blastocyst – a later stage of embryo development. These were sequenced and the researchers found that the editing had indeed worked. Importantly, they could show that the level of off-target mutations was low.

A brave new world?

So does this mean we finally have a cure for debilitating, heritable diseases? It’s important to remember that the study did not achieve a 100% success rate. Even the researchers themselves stress that further research is needed in order to fully understand the potential and limitations of the technique.

In our view, it is unlikely that genome editing would be used to treat the majority of inherited conditions anytime soon. We still can’t be sure how a child with a genetically altered genome will develop over a lifetime, so it seems unlikely that couples carrying a genetic disease would embark on gene editing rather than undergoing already available tests – such as preimplantation genetic diagnosis or prenatal diagnosis – where the embryos or fetus are tested for genetic faults.

-30-

As might be expected there is now a call for public discussion about the ethics about this kind of work. See Part 3.

For anyone who started in the middle of this series, here’s Part 1 featuring an introduction to the technology and some of the issues.

CRISPR and editing the germline in the US (part 1 of 3): In the beginning

There’s been a minor flurry of interest in CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats; also known as CRISPR-CAS9), a gene-editing technique, since a team in Oregon announced a paper describing their work editing the germline. Since I’ve been following the CRISPR-CAS9 story for a while this seems like a good juncture for a more in-depth look at the topic. In this first part I’m including an introduction to CRISPR, some information about the latest US work, and some previous writing about ethics issues raised when Chinese scientists first announced their work editing germlines in 2015 and during the patent dispute between the University of California at Berkeley and Harvard University’s Broad Institute.

Introduction to CRISPR

I’ve been searching for a good description of CRISPR and this helped to clear up some questions for me (Thank you to MIT Review),

For anyone who’s been reading about science for a while, this upbeat approach to explaining how a particular technology will solve all sorts of problems will seem quite familiar. It’s not the most hyperbolic piece I’ve seen but it barely mentions any problems associated with research (for some of the problems see: ‘The interest flurry’ later in part 2).

Oregon team

Steve Connor’s July 26, 2017 article for the MIT (Massachusetts Institute of Technology) Technology Review breaks the news (Note: Links have been removed),

The first known attempt at creating genetically modified human embryos in the United States has been carried out by a team of researchers in Portland, Oregon, MIT Technology Review has learned.

The effort, led by Shoukhrat Mitalipov of Oregon Health and Science University, involved changing the DNA of a large number of one-cell embryos with the gene-editing technique CRISPR, according to people familiar with the scientific results.

Until now, American scientists have watched with a combination of awe, envy, and some alarm as scientists elsewhere were first to explore the controversial practice. To date, three previous reports of editing human embryos were all published by scientists in China.

Now Mitalipov is believed to have broken new ground both in the number of embryos experimented upon and by demonstrating that it is possible to safely and efficiently correct defective genes that cause inherited diseases.

Although none of the embryos were allowed to develop for more than a few days—and there was never any intention of implanting them into a womb—the experiments are a milestone on what may prove to be an inevitable journey toward the birth of the first genetically modified humans.

In altering the DNA code of human embryos, the objective of scientists is to show that they can eradicate or correct genes that cause inherited disease, like the blood condition beta-thalassemia. The process is termed “germline engineering” because any genetically modified child would then pass the changes on to subsequent generations via their own germ cells—the egg and sperm.

Some critics say germline experiments could open the floodgates to a brave new world of “designer babies” engineered with genetic enhancements—a prospect bitterly opposed by a range of religious organizations, civil society groups, and biotech companies.

The U.S. intelligence community last year called CRISPR a potential “weapon of mass destruction.”

Here’s a link to a citation for the groundbreaking paper,

Correction of a pathogenic gene mutation in human embryos by Hong Ma, Nuria Marti-Gutierrez, Sang-Wook Park, Jun Wu, Yeonmi Lee, Keiichiro Suzuki, Amy Koski, Dongmei Ji, Tomonari Hayama, Riffat Ahmed, Hayley Darby, Crystal Van Dyken, Ying Li, Eunju Kang, A.-Reum Park, Daesik Kim, Sang-Tae Kim, Jianhui Gong, Ying Gu, Xun Xu, David Battaglia, Sacha A. Krieg, David M. Lee, Diana H. Wu, Don P. Wolf, Stephen B. Heitner, Juan Carlos Izpisua Belmonte, Paula Amato, Jin-Soo Kim, Sanjiv Kaul, & Shoukhrat Mitalipov. Nature (2017) doi:10.1038/nature23305 Published online 02 August 2017

This paper appears to be open access.

CRISPR Issues: ethics and patents

In my May 14, 2015 posting I mentioned a ‘moratorium’ on germline research, the Chinese research paper, and the stance taken by the US National Institutes of Health (NIH),

The CRISPR technology has reignited a discussion about ethical and moral issues of human genetic engineering some of which is reviewed in an April 7, 2015 posting about a moratorium by Sheila Jasanoff, J. Benjamin Hurlbut and Krishanu Saha for the Guardian science blogs (Note: A link has been removed),

On April 3, 2015, a group of prominent biologists and ethicists writing in Science called for a moratorium on germline gene engineering; modifications to the human genome that will be passed on to future generations. The moratorium would apply to a technology called CRISPR/Cas9, which enables the removal of undesirable genes, insertion of desirable ones, and the broad recoding of nearly any DNA sequence.

Such modifications could affect every cell in an adult human being, including germ cells, and therefore be passed down through the generations. Many organisms across the range of biological complexity have already been edited in this way to generate designer bacteria, plants and primates. There is little reason to believe the same could not be done with human eggs, sperm and embryos. Now that the technology to engineer human germlines is here, the advocates for a moratorium declared, it is time to chart a prudent path forward. They recommend four actions: a hold on clinical applications; creation of expert forums; transparent research; and a globally representative group to recommend policy approaches.

The authors go on to review precedents and reasons for the moratorium while suggesting we need better ways for citizens to engage with and debate these issues,

An effective moratorium must be grounded in the principle that the power to modify the human genome demands serious engagement not only from scientists and ethicists but from all citizens. We need a more complex architecture for public deliberation, built on the recognition that we, as citizens, have a duty to participate in shaping our biotechnological futures, just as governments have a duty to empower us to participate in that process. Decisions such as whether or not to edit human genes should not be left to elite and invisible experts, whether in universities, ad hoc commissions, or parliamentary advisory committees. Nor should public deliberation be temporally limited by the span of a moratorium or narrowed to topics that experts deem reasonable to debate.

I recommend reading the post in its entirety as there are nuances that are best appreciated in the entirety of the piece.

Shortly after this essay was published, Chinese scientists announced they had genetically modified (nonviable) human embryos. From an April 22, 2015 article by David Cyranoski and Sara Reardon in Nature where the research and some of the ethical issues discussed,

In a world first, Chinese scientists have reported editing the genomes of human embryos. The results are published1 in the online journal Protein & Cell and confirm widespread rumours that such experiments had been conducted — rumours that sparked a high-profile debate last month2, 3 about the ethical implications of such work.

In the paper, researchers led by Junjiu Huang, a gene-function researcher at Sun Yat-sen University in Guangzhou, tried to head off such concerns by using ‘non-viable’ embryos, which cannot result in a live birth, that were obtained from local fertility clinics. The team attempted to modify the gene responsible for β-thalassaemia, a potentially fatal blood disorder, using a gene-editing technique known as CRISPR/Cas9. The researchers say that their results reveal serious obstacles to using the method in medical applications.

“I believe this is the first report of CRISPR/Cas9 applied to human pre-implantation embryos and as such the study is a landmark, as well as a cautionary tale,” says George Daley, a stem-cell biologist at Harvard Medical School in Boston, Massachusetts. “Their study should be a stern warning to any practitioner who thinks the technology is ready for testing to eradicate disease genes.”

….

Huang says that the paper was rejected by Nature and Science, in part because of ethical objections; both journals declined to comment on the claim. (Nature’s news team is editorially independent of its research editorial team.)

He adds that critics of the paper have noted that the low efficiencies and high number of off-target mutations could be specific to the abnormal embryos used in the study. Huang acknowledges the critique, but because there are no examples of gene editing in normal embryos he says that there is no way to know if the technique operates differently in them.

Still, he maintains that the embryos allow for a more meaningful model — and one closer to a normal human embryo — than an animal model or one using adult human cells. “We wanted to show our data to the world so people know what really happened with this model, rather than just talking about what would happen without data,” he says.

This, too, is a good and thoughtful read.

There was an official response in the US to the publication of this research, from an April 29, 2015 post by David Bruggeman on his Pasco Phronesis blog (Note: Links have been removed),

In light of Chinese researchers reporting their efforts to edit the genes of ‘non-viable’ human embryos, the National Institutes of Health (NIH) Director Francis Collins issued a statement (H/T Carl Zimmer).

“NIH will not fund any use of gene-editing technologies in human embryos. The concept of altering the human germline in embryos for clinical purposes has been debated over many years from many different perspectives, and has been viewed almost universally as a line that should not be crossed. Advances in technology have given us an elegant new way of carrying out genome editing, but the strong arguments against engaging in this activity remain. These include the serious and unquantifiable safety issues, ethical issues presented by altering the germline in a way that affects the next generation without their consent, and a current lack of compelling medical applications justifying the use of CRISPR/Cas9 in embryos.” …

The US has modified its stance according to a February 14, 2017 article by Jocelyn Kaiser for Science Magazine (Note: Links have been removed),

Editing the DNA of a human embryo to prevent a disease in a baby could be ethically allowable one day—but only in rare circumstances and with safeguards in place, says a widely anticipated report released today.

The report from an international committee convened by the U.S. National Academy of Sciences (NAS) and the National Academy of Medicine in Washington, D.C., concludes that such a clinical trial “might be permitted, but only following much more research” on risks and benefits, and “only for compelling reasons and under strict oversight.” Those situations could be limited to couples who both have a serious genetic disease and for whom embryo editing is “really the last reasonable option” if they want to have a healthy biological child, says committee co-chair Alta Charo, a bioethicist at the University of Wisconsin in Madison.

Some researchers are pleased with the report, saying it is consistent with previous conclusions that safely altering the DNA of human eggs, sperm, or early embryos—known as germline editing—to create a baby could be possible eventually. “They have closed the door to the vast majority of germline applications and left it open for a very small, well-defined subset. That’s not unreasonable in my opinion,” says genome researcher Eric Lander of the Broad Institute in Cambridge, Massachusetts. Lander was among the organizers of an international summit at NAS in December 2015 who called for more discussion before proceeding with embryo editing.

But others see the report as lowering the bar for such experiments because it does not explicitly say they should be prohibited for now. “It changes the tone to an affirmative position in the absence of the broad public debate this report calls for,” says Edward Lanphier, chairman of the DNA editing company Sangamo Therapeutics in Richmond, California. Two years ago, he co-authored a Nature commentary calling for a moratorium on clinical embryo editing.

One advocacy group opposed to embryo editing goes further. “We’re very disappointed with the report. It’s really a pretty dramatic shift from the existing and widespread agreement globally that human germline editing should be prohibited,” says Marcy Darnovsky, executive director of the Center for Genetics and Society in Berkeley, California.

Interestingly, this change of stance occurred just prior to a CRISPR patent decision (from my March 15, 2017 posting),

I have written about the CRISPR patent tussle (Harvard & MIT’s [Massachusetts Institute of Technology] Broad Institute vs the University of California at Berkeley) previously in a Jan. 6, 2015 posting and in a more detailed May 14, 2015 posting. I also mentioned (in a Jan. 17, 2017 posting) CRISPR and its patent issues in the context of a posting about a Slate.com series on Frankenstein and the novel’s applicability to our own time. This patent fight is being bitterly fought as fortunes are at stake.

It seems a decision has been made regarding the CRISPR patent claims. From a Feb. 17, 2017 article by Charmaine Distor for The Science Times,

After an intense court battle, the US Patent and Trademark Office (USPTO) released its ruling on February 15 [2017]. The rights for the CRISPR-Cas9 gene editing technology was handed over to the Broad Institute of Harvard University and the Massachusetts Institute of Technology (MIT).

According to an article in Nature, the said court battle was between the Broad Institute and the University of California. The two institutions are fighting over the intellectual property right for the CRISPR patent. The case between the two started when the patent was first awarded to the Broad Institute despite having the University of California apply first for the CRISPR patent.

Heidi Ledford’s Feb. 17, 2017 article for Nature provides more insight into the situation (Note: Links have been removed),

It [USPTO] ruled that the Broad Institute of Harvard and MIT in Cambridge could keep its patents on using CRISPR–Cas9 in eukaryotic cells. That was a blow to the University of California in Berkeley, which had filed its own patents and had hoped to have the Broad’s thrown out.

The fight goes back to 2012, when Jennifer Doudna at Berkeley, Emmanuelle Charpentier, then at the University of Vienna, and their colleagues outlined how CRISPR–Cas9 could be used to precisely cut isolated DNA1. In 2013, Feng Zhang at the Broad and his colleagues — and other teams — showed2 how it could be adapted to edit DNA in eukaryotic cells such as plants, livestock and humans.

Berkeley filed for a patent earlier, but the USPTO granted the Broad’s patents first — and this week upheld them. There are high stakes involved in the ruling. The holder of key patents could make millions of dollars from CRISPR–Cas9’s applications in industry: already, the technique has sped up genetic research, and scientists are using it to develop disease-resistant livestock and treatments for human diseases.

….

I also noted this eyebrow-lifting statistic,  “As for Ledford’s 3rd point, there are an estimated 763 patent families (groups of related patents) claiming CAS9 leading to the distinct possibility that the Broad Institute will be fighting many patent claims in the future.)

-30-

Part 2 covers three critical responses to the reporting and between them describe the technology in more detail and the possibility of ‘designer babies’.  CRISPR and editing the germline in the US (part 2 of 3): ‘designer babies’?

Part 3 is all about public discussion or, rather, the lack of and need for according to a couple of social scientists. Informally, there is some discussion via pop culture and Joelle Renstrom notes although she is focused on the larger issues touched on by the television series, Orphan Black and as I touch on in my final comments. CRISPR and editing the germline in the US (part 3 of 3): public discussions and pop culture

Using CRISPR to reverse retinosa pigmentosa (eye disease)

Years ago I worked as a publicist for the BC (British Columbia) Motorcycle Federation’s Ride for Sight; they were raising funds for research into retinitis pigmentosa (RP). I hadn’t thought about that in years but it all came back when I saw this April 21, 2017 news item on ScienceDaily,

Using the gene-editing tool CRISPR/Cas9, researchers at University of California San Diego [UCSD] School of Medicine and Shiley Eye Institute at UC San Diego Health, with colleagues in China, have reprogrammed mutated rod photoreceptors to become functioning cone photoreceptors, reversing cellular degeneration and restoring visual function in two mouse models of retinitis pigmentosa.

Caption: This is a confocal micrograph of mouse retina depicting optic fiber layer. Credit: Image courtesy of National Center for Microscopy and Imaging Research, UC San Diego.

An April 21, 2017 UCSD news release by Scott LaFee (also on EurekAlert), which originated the news item, delves further into retinitis pigmentosa and this CRISPR research,

Retinitis pigmentosa (RP) is a group of inherited vision disorders caused by numerous mutations in more than 60 genes. The mutations affect the eyes’ photoreceptors, specialized cells in the retina that sense and convert light images into electrical signals sent to the brain. There are two types: rod cells that function for night vision and peripheral vision, and cone cells that provide central vision (visual acuity) and discern color. The human retina typically contains 120 million rod cells and 6 million cone cells.

In RP, which affects approximately 100,000 Americans and 1 in 4,000 persons worldwide, rod-specific genetic mutations cause rod photoreceptor cells to dysfunction and degenerate over time. Initial symptoms are loss of peripheral and night vision, followed by diminished visual acuity and color perception as cone cells also begin to fail and die. There is no treatment for RP. The eventual result may be legal blindness.

In their published research, a team led by senior author Kang Zhang, MD, PhD, chief of ophthalmic genetics, founding director of the Institute for Genomic Medicine and co-director of biomaterials and tissue engineering at the Institute of Engineering in Medicine, both at UC San Diego School of Medicine, used CRISPR/Cas9 to deactivate a master switch gene called Nrl and a downstream transcription factor called Nr2e3.

CRISPR, which stands for Clustered Regularly Interspaced Short Palindromic Repeats, allows researchers to target specific stretches of genetic code and edit DNA at precise locations, modifying select gene functions. Deactivating either Nrl or Nr2e3 reprogrammed rod cells to become cone cells.

“Cone cells are less vulnerable to the genetic mutations that cause RP,” said Zhang. “Our strategy was to use gene therapy to make the underlying mutations irrelevant, resulting in the preservation of tissue and vision.”

The scientists tested their approach in two different mouse models of RP. In both cases, they found an abundance of reprogrammed cone cells and preserved cellular architecture in the retinas. Electroretinography testing of rod and cone receptors in live mice show improved function.

Zhang said a recent independent study led by Zhijian Wu, PhD, at National Eye Institute, part of the National Institutes of Health, also reached similar conclusions.

The researchers used adeno-associated virus (AAV) to perform the gene therapy, which they said should help advance their work to human clinical trials quicker. “AAV is a common cold virus and has been used in many successful gene therapy treatments with a relatively good safely profile,” said Zhang. “Human clinical trials could be planned soon after completion of preclinical study. There is no treatment for RP so the need is great and pressing. In addition, our approach of reprogramming mutation-sensitive cells to mutation-resistant cells may have broader application to other human diseases, including cancer.”

Here’s a link to and a citation for the paper,

Gene and mutation independent therapy via CRISPR-Cas9 mediated cellular reprogramming in rod photoreceptors by Jie Zhu, Chang Ming, Xin Fu, Yaou Duan, Duc Anh Hoang, Jeffrey Rutgard, Runze Zhang, Wenqiu Wang, Rui Hou, Daniel Zhang, Edward Zhang, Charlotte Zhang, Xiaoke Hao, Wenjun Xiong, and Kang Zhang. Cell Research advance online publication 21 April 2017; doi: 10.1038/cr.2017.57

This paper (it’s in the form of a letter to the editor) is open access.