Tag Archives: Editas Medicine

Congratulations to winners of 2020 Nobel Prize for Chemistry: Dr. Emmanuelle Charpentier & Dr. Jennifer A. Doudna (CRISPR-cas9)

It’s possible there’s a more dramatic development in the field of contemporary gene-editing but it’s indisputable that CRISPR (clustered regularly interspaced short palindromic repeats) -cas9 (CRISPR-associated 9 [protein]) ranks very highly indeed.

The technique, first discovered (or developed) in 2012, has brought recognition in the form of the 2020 Nobel Prize for Chemistry to CRISPR’s two discoverers, Emanuelle Charpentier and Jennifer Doudna.

An October 7, 2020 news item on phys.org announces the news,

The Nobel Prize in chemistry went to two researchers Wednesday [October 7, 2020] for a gene-editing tool that has revolutionized science by providing a way to alter DNA, the code of life—technology already being used to try to cure a host of diseases and raise better crops and livestock.

Emmanuelle Charpentier of France and Jennifer A. Doudna of the United States won for developing CRISPR-cas9, a very simple technique for cutting a gene at a specific spot, allowing scientists to operate on flaws that are the root cause of many diseases.

“There is enormous power in this genetic tool,” said Claes Gustafsson, chair of the Nobel Committee for Chemistry.

More than 100 clinical trials are underway to study using CRISPR to treat diseases, and “many are very promising,” according to Victor Dzau, president of the [US] National Academy of Medicine.

“My greatest hope is that it’s used for good, to uncover new mysteries in biology and to benefit humankind,” said Doudna, who is affiliated with the University of California, Berkeley, and is paid by the Howard Hughes Medical Institute, which also supports The Associated Press’ Health and Science Department.

The prize-winning work has opened the door to some thorny ethical issues: When editing is done after birth, the alterations are confined to that person. Scientists fear CRISPR will be misused to make “designer babies” by altering eggs, embryos or sperm—changes that can be passed on to future generations.

Unusually for phys.org, this October 7, 2020 news item is not a simple press/news release reproduced in its entirety but a good overview of the researchers’ accomplishments and a discussion of some of the issues associated with CRISPR along with the press release at the end.

I have covered some CRISPR issues here including intellectual property (see my March 15, 2017 posting titled, “CRISPR patent decision: Harvard’s and MIT’s Broad Institute victorious—for now‘) and designer babies (as exemplified by the situation with Dr. He Jiankui; see my July 28, 2020 post titled, “July 2020 update on Dr. He Jiankui (the CRISPR twins) situation” for more details about it).

An October 7, 2020 article by Michael Grothaus for Fast Company provides a business perspective (Note: A link has been removed),

Needless to say, research by the two scientists awarded the Nobel Prize in Chemistry today has the potential to change the course of humanity. And with that potential comes lots of VC money and companies vying for patents on techniques and therapies derived from Charpentier’s and Doudna’s research.

One such company is Doudna’s Editas Medicine [according to my search, the only company associated with Doudna is Mammoth Biosciences, which she co-founded], while others include Caribou Biosciences, Intellia Therapeutics, and Casebia Therapeutics. Given the world-changing applications—and the amount of revenue such CRISPR therapies could bring in—it’s no wonder that such rivalry is often heated (and in some cases has led to lawsuits over the technology and its patents).

As Doudna explained in her book, A Crack in Creation: Gene Editing and the Unthinkable Power to Control Evolution, cowritten by Samuel H. Sternberg …, “… —but we could also have woolly mammoths, winged lizards, and unicorns.” And as for that last part, she made clear, “No, I am not kidding.”

Everybody makes mistakes and the reference to Editas Medicine is the only error I spotted. You can find out more about Mammoth Biosciences here and while Dr. Doudna’s comment, “My greatest hope is that it’s used for good, to uncover new mysteries in biology and to benefit humankind,” is laudable it would seem she wishes to profit from the discovery. Mammoth Biosciences is a for-profit company as can be seen at the end of the Mammoth Biosciences’ October 7, 2020 congratulatory news release,

About Mammoth Biosciences

Mammoth Biosciences is harnessing the diversity of nature to power the next-generation of CRISPR products. Through the discovery and development of novel CRISPR systems, the company is enabling the full potential of its platform to read and write the code of life. By leveraging its internal research and development and exclusive licensing to patents related to Cas12, Cas13, Cas14 and Casɸ, Mammoth Biosciences can provide enhanced diagnostics and genome editing for life science research, healthcare, agriculture, biodefense and more. Based in San Francisco, Mammoth Biosciences is co-founded by CRISPR pioneer Jennifer Doudna and Trevor Martin, Janice Chen, and Lucas Harrington. The firm is backed by top institutional investors [emphasis mine] including Decheng, Mayfield, NFX, and 8VC, and leading individual investors including Brook Byers, Tim Cook, and Jeff Huber.

An October 7, 2029 Nobel Prize press release, which unleashed all this interest in Doudna and Charpentier, notes this,

Prize amount: 10 million Swedish kronor, to be shared equally between the Laureates.

In Canadian money that amount is $1,492,115.03 (as of Oct. 9, 2020 12:40 PDT when I checked a currency converter).

Ordinarily there’d be a mildly caustic comment from me about business opportunities and medical research but this is a time for congratulations to both Dr. Emanuelle Charpentier and Dr. Jennifer Doudna.

Immune to CRISPR?

I guess if you’re going to use bacteria as part of your gene editing technology (CRISPR [clustered regularly interspaced short palindromic repeats]/Cas9) then, you might half expect the body’s immune system may have developed some defenses. A Jan. 9, 2018 article by Sarah Zhang for The Atlantic provides some insight into what the new research suggests (Note: Links have been removed),

2018 is supposed to be the year of CRISPR in humans. The first U.S. and European clinical trials that test the gene-editing tool’s ability to treat diseases—such as sickle-cell anemia, beta thalassemia, and a type of inherited blindness—are slated to begin this year.

But the year has begun on a cautionary note. On Friday [January 5, 2018], Stanford researchers posted a preprint (which has not been peer reviewed) to the website biorXiv highlighting a potential obstacle to using CRISPR in humans: Many of us may already be immune to it. That’s because CRISPR actually comes from bacteria that often live on or infect humans, and we have built up immunity to the proteins from these bacteria over our lives.

Not all CRISPR therapies in humans will be doomed. “We don’t think this is the end of the story. This is the start of the story,” says Porteus [Matthew Porteus, a pediatrician and stem-cell researcher at Stanford]. There are likely ways around the problem of immunity to CRISPR proteins, and many of the early clinical trials appear to be designed around this problem.

Porteus and his colleagues focused on two versions of Cas9, the bacterial protein mostly commonly used in CRISPR gene editing. One comes from Staphylococcus aureus, which often harmlessly lives on skin but can sometimes causes staph infections, and another from Streptococcus pyogenes, which causes strep throat but can also become “flesh-eating bacteria” when it spreads to other parts of the body. So yeah, you want your immune system to be on guard against these bacteria.

The human immune system has a couple different ways of recognizing foreign proteins, and the team tested for both. First, they looked to see if people have molecules in their blood called antibodies that can specifically bind to Cas9. Among 34 people they tested, 79 percent had antibodies against the staph Cas9 and 65 percent against the strep Cas9.

The Stanford team only tested for preexisting immunity against Cas9, but anytime you inject a large bacterial protein into the human body, it can provoke an immune response. After all, that’s how the immune system learns to fight off bacteria it’s never seen before. (Preexisting immunity can make the response faster and more robust, though.)

The danger of the immune system turning on a patient’s body hangs over a lot of research into correcting genes. In the late 1990s and 2000s, research into gene therapy was derailed by the death of 18-year-old Jesse Gelsinger, who died from an immune reaction to the virus used to deliver the corrected gene. This is the worst-case scenario that the CRISPR world hopes to avoid.

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

Identification of Pre-Existing Adaptive Immunity to Cas9 Proteins in Humans by Carsten Trevor Charlesworth, Priyanka S Deshpande, Daniel P Dever, Beruh Dejene, Natalia Gomez-Ospina, Sruthi Mantri, Mara Pavel-Dinu, Joab Camarena, Kenneth I Weinberg, Matthew H Porteus. bioRxiv posted January 5, 2018 doi: https://doi.org/10.1101/243345

This article is a preprint and has not been peer-reviewed …

This preprint (not yet published paper) is open access and open for feedback.

Meanwhile, the year of CRISPR takes off (from a January 10, 2018 American Chemical Society news release on EurekAlert),

This year could be a defining one for CRISPR, the gene editing technique, which has been hailed as an important breakthrough in laboratory research. That’s because the first company-sponsored clinical studies will be conducted to see if it can help treat diseases in humans, according to an article in Chemical & Engineering News (C&EN), the weekly newsmagazine of the American Chemical Society.

C&EN Assistant Editor Ryan Cross reports that a big push is coming from industry, specifically from three companies that are each partly founded by one of the three inventors of the method. They are zeroing in on the blood diseases called sickle-cell anemia and β-thalassemia, mostly because their precise cause is known. In these diseases, hemoglobin doesn’t function properly, leading to severe health issues in some people. Crispr Therapeutics and Intellia Therapeutics plan to test the technique to boost levels of an alternative version of healthy hemoglobin. Editas Medicine, however, will also use CRISPR to correct mutations in the faulty hemoglobin gene. Labs led by university researchers are also joining the mix, starting or continuing clinical trials with the approach in 2018.

Because CRISPR is being used to cut a cell’s DNA and insert a new sequence, concerns have been raised about the potential for accidents. A cut in the wrong place could mean introducing a new mutation that could be benign — or cancerous. But according to proponents of the method, researchers are conducting extensive computer predictions and in vitro tests to help avoid this outcome.

The January 8, 2018 Chemical and Engineering News (C&EN) open access article by Ryan Cross is here.

Finally, if you are interested in how this affects research as it’s being developed, there’s University of British Columbia researcher Rosie Redfield’s January 16, 2018 posting on RRResearch blog,

Thursday’s [January 11, 2018] post described the hypothesis that bacteria might use gene transfer agent particles to inoculate other cells in the population with fragments of phage DNA, and outlined an experiment to test this.  Now I’m realizing that I need to know a lot more about the kind of immunity I should expect to see if this GTA-as-vaccine hypothesis is correct.

That should give you some idea of what I meant by “research as it’s being developed.” Redfield’s blog is not for the mildly interested.

Redfield is well-known internationally as being one of the first to refute research which suggested the existence of an ‘arsenic bacterium’ (see my Dec. 8, 2010 posting: My apologies for arsenic blooper. She’s first mentioned in the second excerpt, second paragraph.) The affair was known online as #arseniclife. There’s a May 27, 2011 essay by Carl Zimmer on Slate titled: The Discovery of Arsenic-Based Twitter: How #arseniclife changed science.

CRISPR genome editing tools and human genetic engineering issues

This post is going to feature a human genetic engineering roundup of sorts.

First, the field of human genetic engineering encompasses more than the human genome as this paper (open access until June 5, 2015) notes in the context of a discussion about a specific CRISPR gene editing tool,

CRISPR-Cas9 Based Genome Engineering: Opportunities in Agri-Food-Nutrition and Healthcare by Rajendran Subin Raj Cheri Kunnumal, Yau Yuan-Yeu, Pandey Dinesh, and Kumar Anil. OMICS: A Journal of Integrative Biology. May 2015, 19(5): 261-275. doi:10.1089/omi.2015.0023 Published Online Ahead of Print: April 14, 2015

Here’s more about the paper from a May 7, 2015 Mary Ann Liebert publisher news release on EurekAlert,

Researchers have customized and refined a technique derived from the immune system of bacteria to develop the CRISPR-Cas9 genome engineering system, which enables targeted modifications to the genes of virtually any organism. The discovery and development of CRISPR-Cas9 technology, its wide range of potential applications in the agriculture/food industry and in modern medicine, and emerging regulatory issues are explored in a Review article published in OMICS: A Journal of Integrative Biology, …

“CRISPR-Cas9 Based Genome Engineering: Opportunities in Agri-Food-Nutrition and Healthcare” provides a detailed description of the CRISPR system and its applications in post-genomics biology. Subin Raj, Cheri Kunnumal Rajendran, Dinish Pandey, and Anil Kumar, G.B. Pant University of Agriculture and Technology (Uttarakhand, India) and Yuan-Yeu Yau, Northeastern State University (Broken Arrow, OK) describe the advantages of the RNA-guided Cas9 endonuclease-based technology, including the activity, specificity, and target range of the enzyme. The authors discuss the rapidly expanding uses of the CRISPR system in both basic biological research and product development, such as for crop improvement and the discovery of novel therapeutic agents. The regulatory implications of applying CRISPR-based genome editing to agricultural products is an evolving issue awaiting guidance by international regulatory agencies.

“CRISPR-Cas9 technology has triggered a revolution in genome engineering within living systems,” says OMICS Editor-in-Chief Vural Özdemir, MD, PhD, DABCP. “This article explains the varied applications and potentials of this technology from agriculture to nutrition to medicine.

Intellectual property (patents)

The CRISPR technology has spawned a number of intellectual property (patent) issues as a Dec. 21,2014 post by Glyn Moody on Techdirt stated,

Although not many outside the world of the biological sciences have heard of it yet, the CRISPR gene editing technique may turn out to be one of the most important discoveries of recent years — if patent battles don’t ruin it. Technology Review describes it as:

… an invention that may be the most important new genetic engineering technique since the beginning of the biotechnology age in the 1970s. The CRISPR system, dubbed a “search and replace function” for DNA, lets scientists easily disable genes or change their function by replacing DNA letters. During the last few months, scientists have shown that it’s possible to use CRISPR to rid mice of muscular dystrophy, cure them of a rare liver disease, make human cells immune to HIV, and genetically modify monkeys.

Unfortunately, rivalry between scientists claiming the credit for key parts of CRISPR threatens to spill over into patent litigation:

[A researcher at the MIT-Harvard Broad Institute, Feng] Zhang cofounded Editas Medicine, and this week the startup announced that it had licensed his patent from the Broad Institute. But Editas doesn’t have CRISPR sewn up. That’s because [Jennifer] Doudna, a structural biologist at the University of California, Berkeley, was a cofounder of Editas, too. And since Zhang’s patent came out, she’s broken off with the company, and her intellectual property — in the form of her own pending patent — has been licensed to Intellia, a competing startup unveiled only last month. Making matters still more complicated, [another CRISPR researcher, Emmanuelle] Charpentier sold her own rights in the same patent application to CRISPR Therapeutics.

Things are moving quickly on the patent front, not least because the Broad Institute paid extra to speed up its application, conscious of the high stakes at play here:

Along with the patent came more than 1,000 pages of documents. According to Zhang, Doudna’s predictions in her own earlier patent application that her discovery would work in humans was “mere conjecture” and that, instead, he was the first to show it, in a separate and “surprising” act of invention.

The patent documents have caused consternation. The scientific literature shows that several scientists managed to get CRISPR to work in human cells. In fact, its easy reproducibility in different organisms is the technology’s most exciting hallmark. That would suggest that, in patent terms, it was “obvious” that CRISPR would work in human cells, and that Zhang’s invention might not be worthy of its own patent.


Ethical and moral issues

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.” …

More than CRISPR

As well, following on the April 22, 2015 Nature article about the controversial research, the Guardian published an April 26, 2015 post by Filippa Lentzos, Koos van der Bruggen and Kathryn Nixdorff which makes the case that CRISPR techniques do not comprise the only worrisome genetic engineering technology,

The genome-editing technique CRISPR-Cas9 is the latest in a series of technologies to hit the headlines. This week Chinese scientists used the technology to genetically modify human embryos – the news coming less than a month after a prominent group of scientists had called for a moratorium on the technology. The use of ‘gene drives’ to alter the genetic composition of whole populations of insects and other life forms has also raised significant concern.

But the technology posing the greatest, most immediate threat to humanity comes from ‘gain-of-function’ (GOF) experiments. This technology adds new properties to biological agents such as viruses, allowing them to jump to new species or making them more transmissible. While these are not new concepts, there is grave concern about a subset of experiments on influenza and SARS viruses which could metamorphose them into pandemic pathogens with catastrophic potential.

In October 2014 the US government stepped in, imposing a federal funding pause on the most dangerous GOF experiments and announcing a year-long deliberative process. Yet, this process has not been without its teething-problems. Foremost is the de facto lack of transparency and open discussion. Genuine engagement is essential in the GOF debate where the stakes for public health and safety are unusually high, and the benefits seem marginal at best, or non-existent at worst. …

Particularly worrisome about the GOF process is that it is exceedingly US-centric and lacks engagement with the international community. Microbes know no borders. The rest of the world has a huge stake in the regulation and oversight of GOF experiments.

Canadian perspective?

I became somewhat curious about the Canadian perspective on all this genome engineering discussion and found a focus on agricultural issues in the single Canadian blog piece I found. It’s an April 30, 2015 posting by Lisa Willemse on Genome Alberta’s Livestock blog has a twist in the final paragraph,

The spectre of undesirable inherited traits as a result of DNA disruption via genome editing in human germline has placed the technique – and the ethical debate – on the front page of newspapers around the globe. Calls for a moratorium on further research until both the ethical implications can be worked out and the procedure better refined and understood, will undoubtedly temper research activities in many labs for months and years to come.

On the surface, it’s hard to see how any of this will advance similar research in livestock or crops – at least initially.

Groups already wary of so-called “frankenfoods” may step up efforts to prevent genome-edited food products from hitting supermarket shelves. In the EU, where a stringent ban on genetically-modified (GM) foods is already in place, there are concerns that genome-edited foods will be captured under this rubric, holding back many perceived benefits. This includes pork and beef from animals with disease resistance, lower methane emissions and improved feed-to-food ratios, milk from higher-yield or hornless cattle, as well as food and feed crops with better, higher quality yields or weed resistance.

Still, at the heart of the human germline editing is the notion of a permanent genetic change that can be passed on to offspring, leading to concerns of designer babies and other advantages afforded only to those who can pay. This is far less of a concern in genome-editing involving crops and livestock, where the overriding aim is to increase food supply for the world’s population at lower cost. Given this, and that research for human medical benefits has always relied on safety testing and data accumulation through experimentation in non-human animals, it’s more likely that any moratorium in human studies will place increased pressure to demonstrate long-term safety of such techniques on those who are conducting the work in other species.

Willemse’s last paragraph offers a strong contrast to the Guardian and Nature pieces.

Finally, there’s a May 8, 2015 posting (which seems to be an automat4d summary of an article in the New Scientist) on a blog maintained by the Canadian Raelian Movement. These are people who believe that alien scientists landed on earth and created all the forms of life on this planet. You can find  more on their About page. In case it needs to be said, I do not subscribe to this belief system but I do find it interesting in and of itself and because one of the few Canadian sites that I could find offering an opinion on the matter even if it is in the form of a borrowed piece from the New Scientist.

CRISPR gene editing technique and patents

I have two items about the CRISPR gene editing technique. The first concerns a new use for the CRISPR technique developed by researchers at Johns Hopkins University School of Medicine described in a Jan. 5, 2015 Johns Hopkins University news release on EurekAlert,

A powerful “genome editing” technology known as CRISPR has been used by researchers since 2012 to trim, disrupt, replace or add to sequences of an organism’s DNA. Now, scientists at Johns Hopkins Medicine have shown that the system also precisely and efficiently alters human stem cells.

“Stem cell technology is quickly advancing, and we think that the days when we can use iPSCs [human-induced pluripotent stem cells] for human therapy aren’t that far away,” says Zhaohui Ye, Ph.D., an instructor of medicine at the Johns Hopkins University School of Medicine. “This is one of the first studies to detail the use of CRISPR in human iPSCs, showcasing its potential in these cells.”

CRISPR originated from a microbial immune system that contains DNA segments known as clustered regularly interspaced short palindromic repeats. The engineered editing system makes use of an enzyme that nicks together DNA with a piece of small RNA that guides the tool to where researchers want to introduce cuts or other changes in the genome.

Previous research has shown that CRISPR can generate genomic changes or mutations through these interventions far more efficiently than other gene editing techniques, such as TALEN, short for transcription activator-like effector nuclease.

Despite CRISPR’s advantages, a recent study suggested that it might also produce a large number of “off-target” effects in human cancer cell lines, specifically modification of genes that researchers didn’t mean to change.

To see if this unwanted effect occurred in other human cell types, Ye; Linzhao Cheng, Ph.D., a professor of medicine and oncology in the Johns Hopkins University School of Medicine; and their colleagues pitted CRISPR against TALEN in human iPSCs, adult cells reprogrammed to act like embryonic stem cells. Human iPSCs have already shown enormous promise for treating and studying disease.

The researchers compared the ability of both genome editing systems to either cut out pieces of known genes in iPSCs or cut out a piece of these genes and replace it with another. As model genes, the researchers used JAK2, a gene that when mutated causes a bone marrow disorder known as polycythemia vera; SERPINA1, a gene that when mutated causes alpha1-antitrypsin deficiency, an inherited disorder that may cause lung and liver disease; and AAVS1, a gene that’s been recently discovered to be a “safe harbor” in the human genome for inserting foreign genes.

Their comparison found that when simply cutting out portions of genes, the CRISPR system was significantly more efficient than TALEN in all three gene systems, inducing up to 100 times more cuts. However, when using these genome editing tools for replacing portions of the genes, such as the disease-causing mutations in JAK2 and SERPINA1 genes, CRISPR and TALEN showed about the same efficiency in patient-derived iPSCs, the researchers report.

Contrary to results of the human cancer cell line study, both CRISPR and TALEN had the same targeting specificity in human iPSCs, hitting only the genes they were designed to affect, the team says. The researchers also found that the CRISPR system has an advantage over TALEN: It can be designed to target only the mutation-containing gene without affecting the healthy gene in patients, where only one copy of a gene is affected.

The findings, together with a related study that was published earlier in a leading journal of stem cell research (Cell Stem Cell), offer reassurance that CRISPR will be a useful tool for editing the genes of human iPSCs with little risk of off-target effects, say Ye and Cheng.

“CRISPR-mediated genome editing opens the door to many genetic applications in biologically relevant cells that can lead to better understanding of and potential cures for human diseases,” says Cheng.

Here’s a link to and citation for the paper by the Johns Hopkins researchers,

Efficient and Allele-Specific Genome Editing of Disease Loci in Human iPSCs by Cory Smith, Leire Abalde-Atristain, Chaoxia He, Brett R Brodsky, Evan M Braunstein, Pooja Chaudhari, Yoon-Young Jang, Linzhao Cheng and Zhaohui Ye. Molecular Therapy (24 November 2014) | doi:10.1038/mt.2014.226

This paper is behind a paywall.

Not mentioned in the Johns Hopkins Medicine news release is a brewing patent battle over the CRISPR technique. A Dec. 31, 2014 post by Glyn Moody for Techdirt lays out the situation (Note: Links have been removed),

Although not many outside the world of the biological sciences have heard of it yet, the CRISPR gene editing technique may turn out to be one of the most important discoveries of recent years — if patent battles don’t ruin it. Technology Review describes it as:

    an invention that may be the most important new genetic engineering technique since the beginning of the biotechnology age in the 1970s. The CRISPR system, dubbed a “search and replace function” for DNA, lets scientists easily disable genes or change their function by replacing DNA letters. During the last few months, scientists have shown that it’s possible to use CRISPR to rid mice of muscular dystrophy, cure them of a rare liver disease, make human cells immune to HIV, and genetically modify monkeys.

Unfortunately, rivalry between scientists claiming the credit for key parts of CRISPR threatens to spill over into patent litigation …

Moody describes three scientists vying for control via their patents,

[A researcher at the MIT-Harvard Broad Institute, Feng] Zhang cofounded Editas Medicine, and this week the startup announced that it had licensed his patent from the Broad Institute. But Editas doesn’t have CRISPR sewn up.

That’s because [Jennifer] Doudna, a structural biologist at the University of California, Berkeley, was a cofounder of Editas, too. And since Zhang’s patent came out, she’s broken off with the company, and her intellectual property — in the form of her own pending patent — has been licensed to Intellia, a competing startup unveiled only last month.

Making matters still more complicated, [another CRISPR researcher, Emmanuelle] Charpentier sold her own rights in the same patent application to CRISPR Therapeutics.

Moody notes,

Whether obvious or not, it looks like the patent granted may complicate turning the undoubtedly important CRISPR technique into products. That, in its turn, will mean delays for life-changing and even life-saving therapies: for example, CRISPR could potentially allow the defective gene that causes serious problems for those with cystic fibrosis to be edited to produce normal proteins, thus eliminating those problems.

It’s dispiriting to think that potentially valuable therapies could be lost to litigation battles particularly since the researchers are academics and their work was funded by taxpayers. In any event, I hope sanity reigns and they are able to avoid actions which will grind research down to a standstill.