A team of physicians and laboratory scientists has taken a key step toward a cure for sickle cell disease, using CRISPR-Cas9 gene editing to fix the mutated gene responsible for the disease in stem cells from the blood of affected patients.
For the first time, they have corrected the mutation in a proportion of stem cells that is high enough to produce a substantial benefit in sickle cell patients.
The researchers from UC Berkeley, UC San Francisco Benioff Children’s Hospital Oakland Research Institute (CHORI) and the University of Utah School of Medicine hope to re-infuse patients with the edited stem cells and alleviate symptoms of the disease, which primarily afflicts those of African descent and leads to anemia, painful blood blockages and early death.
“We’re very excited about the promise of this technology,” said Jacob Corn, a senior author on the study and scientific director of the Innovative Genomics Initiative at UC Berkeley. “There is still a lot of work to be done before this approach might be used in the clinic, but we’re hopeful that it will pave the way for new kinds of treatment for patients with sickle cell disease.”
In tests in mice, the genetically engineered stem cells stuck around for at least four months after transplantation, an important benchmark to ensure that any potential therapy would be lasting.
“This is an important advance because for the first time we show a level of correction in stem cells that should be sufficient for a clinical benefit in persons with sickle cell anemia,” said co-author Mark Walters, a pediatric hematologist and oncologist and director of UCSF Benioff Oakland’s Blood and Marrow Transplantation Program.
The results were reported in the Oct. 12 issue of the online journal Science Translational Medicine.
Sickle cell disease is a recessive genetic disorder caused by a single mutation in both copies of a gene coding for beta-globin, a protein that forms part of the oxygen-carrying molecule hemoglobin. This homozygous defect causes hemoglobin molecules to stick together, deforming red blood cells into a characteristic “sickle” shape. These misshapen cells get stuck in blood vessels, causing blockages, anemia, pain, organ failure and significantly shortened lifespan. Sickle cell disease is particularly prevalent in African Americans and the sub-Saharan African population, affecting hundreds of thousands of people worldwide.
The goal of the multi-institutional team is to develop genome engineering-based methods for correcting the disease-causing mutation in each patient’s own stem cells to ensure that new red blood cells are healthy.
The team used CRISPR-Cas9 to correct the disease-causing mutation in hematopoietic stem cells — precursor cells that mature into red blood cells — isolated from whole blood of sickle cell patients. The corrected cells produced healthy hemoglobin, which mutated cells do not make at all.
Future pre-clinical work will require additional optimization, large-scale mouse studies and rigorous safety analysis, the researchers emphasize. Corn and his lab have joined with Walters, an expert in developing curative treatments such as bone marrow transplant and gene therapy for sickle cell disease, to initiate an early-phase clinical trial to test this new treatment within the next five years.
Notably, research groups might be able to apply the approach described in this study to develop treatments for other blood diseases such as ?-thalassemia, severe combined immunodeficiency (SCID), chronic granulomatous disease, rare disorders like Wiskott-Aldrich syndrome and Fanconi anemia, and even HIV infection.
“Sickle cell disease is just one of many blood disorders caused by a single mutation in the genome,” Corn said. “It’s very possible that other researchers and clinicians could use this type of gene editing to explore ways to cure a large number of diseases.”
“There is a clear path for developing therapies for certain diseases,” said co-senior author Dana Carroll of the University of Utah, who co-developed one of the first genome editing techniques over a decade ago. “It’s very gratifying to see gene editing technology being brought to practical applications.”
The work is the fruit of the Innovative Genomics Initiative, a joint effort between UC Berkeley and UCSF that aims to correct DNA mutations that underlie human disease using CRISPR-Cas9, a pioneering technology co-developed by scientists at UC Berkeley that has made genome editing easier and more efficient than ever before.
The project also leverages the expertise of physicians and scientists at UCSF Benioff Children’s Hospital Oakland, a major center for research and treatment of sickle cell disease, and Carroll’s expertise in the field of genome engineering.
In addition to Corn, Walters and Carroll, other co-authors are Mark DeWitt, Nicolas Bray, Tianjiao Wang and Therese Mitros of UC Berkeley; Wendy Magis, Seok-Jin Heo, Denise Muñoz, Dario Boffelli and David Martin of CHORI; Jennifer Berman of Bio-Rad Laboratories in Pleasanton, California; and Fabrizia Urbinati and Donald Kohn of UCLA.
The research is supported by the National Institutes of Health, the Li Ka Shing Foundation, the Siebel Scholars Fund, the Jordan Family Fund and the Doris Duke Charitable Foundation.
A team that includes a Virginia Tech plant scientist recently used life sciences technology to edit 14 target sites encompassing eight plant genes at a time, without making unintended changes elsewhere in the genome.
The technology, a genome-editing tool called CRISPR-Cas9, revolutionized the life sciences when it appeared on the market in 2012. It is proving useful in the plant science community as a powerful tool for the improvement of agricultural crops.
The ability to alter several genes at once promises to advance researchers’ understanding of how genes interact to shape plant development and responses to environmental changes. However, a challenge of this technology has been identifying the impact of editing on genomic regions that were not targeted.
David Haak, an assistant professor of plant pathology, physiology, and weed science in the College of Agriculture and Life Sciences, developed a bioinformatics program using deep sequencing data to test whether the team’s editing of the genome of the Arabidopsis plant was both efficient and specific in its targeting.
The team’s finding that CRISPR-Cas9 is a reliable method for multi-gene editing of this particular plant species was published in PLOS ONE on Sept. 13.
“We were surprised to see that we had targeted gene editing efficiencies ranging from 30-85 percent with no detectable off-target editing,” said Haak, who is also affiliated with the university’s Fralin Life Science Institute and the Global Change Center.
“The ability to edit gene function in a specific manner using CRISPR-Cas9 has the potential to really change how we study plants in the lab and improve crop efficiency,” said co-author Zachary Nimchuk, an assistant professor of biology at the University of North Carolina. “But, there have been concerns about the potential for undesired off-target effects. We tested this in plants, targeting 14 sites at once, and found no off-target events in a large population of plants. Our data expands on previous work to suggest that, at least in Arabidopsis, off-target events are going to be extremely rare with Cas9.”
For (probably) the first time ever, plants modified with the “genetic scissors” CRISPR-Cas9 has been cultivated, harvested and cooked.
Stefan Jansson, professor in Plant Cell and Molecular Biology at Umeå University, served pasta with “CRISPRy” vegetable fry to a radio reporter. Although the meal only fed two people, it was still the first step towards a future where science can better provide farmers and consumers across the world with healthy, beautiful and hardy plants.
CRISPR (Clustered regularly interspaced short palindromic repeats)-Cas9 is a complicated name for an easy, but targeted, way of changing the genes of an organism. The decisive discovery was published in 2012 by researchers at Umeå University, and the ”Swiss army knife of genetic engineering” has been predicted to change the world. With CRISPR-Cas9, researchers can either replace one of the billions of “letters” present in an organism’s genome (i.e. the entire gene pool consisting of DNA) or remove short segments, similar to when you edit a written text in a word processor. The technology is called “gene editing” or “genome editing”.
The first clinical applications are underway; maybe we can soon cure hereditary disease using this technology. However, the situation differs somewhat in the agricultural field. There, the issue is not IF researchers can create plants leading to a more sustainable land management, but rather if these will be allowed in farming. Will plants whose genome has been edited using CRISPR-Cas9 fall under GMO legislation or not? If they do, it makes them illegal to plant in great parts of the world. If not, they will – just like other plants – be allowed to be grown at the farmers own discretion.
Can be cultivated legally
The EU has avoided answering the question, but in November 2015 the Swedish Board of Agriculture interpreted the law as if only a segment of DNA has been removed and no “foreign DNA” has been inserted, it is not to be regarded as a genetically modified organism – a GMO. That also means that the plant can be cultivated without prior permission. In spring 2016, American authorities stated that they agreed. The organism in question there was a mushroom who had lost the part of its DNA that made it go brown. This opens up for using the technology to develop plants of the future.
This summer has been the first time that plants that have been gene-edited using CRISPR-Cas9 – in a way that does not classify the plant as GMO – have been allowed to be cultivated outside of the lab. This is definitely the first time in Europe, and even if it been done before in other parts of the world, it has been kept secret. This time, it was a cabbage plant and the Radio Sweden gardening show “Odla med P1” took part in the harvest leading to the probably first-ever meal of CRISPR-Cas9 genome-edited plants. The first CRISPR meal to have been enjoyed was “Tagliatelle with CRISPRy fried vegetables”.
“The CRISPR-plants in question grew in a pallet collar in a garden outside of Umeå in the north of Sweden and were neither particularly different nor nicer looking than anything else,” says plant scientist Stefan Jansson. But they represent both a new phase of agriculture where scientific advances will be implemented in new plant species and that to a small or large extent will be made available to farmers across the world. In other words: a meal for the future.
Gene-editing technique to treat lung cancer is due to be tested in people in August
Chinese scientists are on the verge of being first in the world to inject people with cells modified using the CRISPR–Cas9 gene-editing technique.
A team led by Lu You, an oncologist at Sichuan University’s West China Hospital in Chengdu, plans to start testing such cells in people with lung cancer next month. The clinical trial received ethical approval from the hospital’s review board on July 6.
“It’s an exciting step forward,” says Carl June, a clinical researcher in immunotherapy at the University of Pennsylvania in Philadelphia.
Scientists delineate molecular details of a new bacterial CRISPR-Cpf1 system and open possible avenue for alternative gene editing uses like targeting several genes in parallel
Only a few years after its discovery, it is difficult to conceive of genetics without the CRISPR-Cas9 enzyme scissors, which allow for a very simple, versatile and reliable modification of DNA of various organisms. Since its discovery, scientists throughout the world have been working on ways of further improving or adjusting the CRISPR-Cas9 system to their specific needs.
Researchers from the Max Planck Institute for Infection Biology in Berlin, the Umeå University in Sweden and the Helmholtz Centre for Infection Research in Braunschweig have now discovered a feature of the CRISPR-associated protein Cpf1 that has previously not been observed in this family of enzymes: Cpf1 exhibits dual, RNA and DNA, cleavage activity. In contrast to CRISPR-Cas9, Cpf1 is able to process the pre-crRNA on its own, and then using the processed RNA to specifically target and cut DNA. Not requiring a host derived RNase and the tracrRNA makes this the most minimalistic CRISPR immune system known to date.
The mechanism of combining two separate catalytic moieties in one allows for possible new avenues for sequence specific genome engineering, most importantly facilitation of targeting multiple sites at once, the so-called multiplexing.
CRISPR-Cas is part of the immune system of bacteria and is used to fight viruses. In the CRISPR-Cas9 system, the enzyme Cas9 cuts the virus DNA at a location specified by an RNA molecule – known as CRISPR RNA (crRNA) in complex with another RNA, the so-called tracrRNA. This puts the pathogens out of action.