Едитовање људског генома - CRISPR-Cas9

[александар живаљев]

ОБРАЗОВАЊЕ И ЕТИКА ЗА БУДУЋНОСТ: Неуморни Срђа Јанковић је у емисији "Соларис" (РБ2) разговарао о техници "замијене ДНК записа" -CRISPR-Cas9 са професорком Иваном Новаковић.Jennifer Doudna, пионир технике едитовања генома, о којој је код нас писао само најозбиљнији  недјељник (без шале!), "Забавник", објавила је истовремено чланак који, због тема које покреће, може да буде занимљив и теолозима специјализованим за биоетику.

Захваљујем на упутима на чланак и емисију: професору Зорану Радовановићу и Срђи Јанковићу.

 

Саговорница: проф. др Ивана Новаковић, Институт за хуману генетику Медицинског факултета Универзитета у Београду 

Почетком децембра, у Вашингтону је одржана међународна научна конференција посвећена биоетичким питањима везаним за примену савремених метода генетичког инжињерства у истраживањима усмереним ка новим могућностима медицине. Непосредан повод за нову расправу је сазревање експерименталне технике познате као CRISPR-Cas9 која, за разлику од већине досадашњих начина уношења генетичких модификација, омогућује научницима да изабране генске секвенце мењају готово у потпуности по вољи – да "едитују" геном као што се исправља неки текст. Разуме се, потенцијална добробит од такве моћне технологије је огромна, али је њена евентуална употреба нужно скопчана са читавим низом суштинских биоетичких питања, међу којима се истичу опасност од разноврсних злоупотреба, ризик нежељених последица које би на постојећем нивоу знања могле да се превиде, као и тешкоће јасног дефинисања границе која раздваја патолошке мутације – које је оправдано "преправити" уз помоћ система CRISPR-Cas9 у функционалне генске секвенце – од непрегледног богатства физиолошких варијацијâ, мање или више повољних или неповољних за своје носиоце у датом контексту, чије би слободно исправљање представљало отварање Пандорине кутије "дизајнирања људских бића". Иако се званичне препоруке светске научне заједнице о етички допустивом начину коришћења технологије едитовања генома очекују тек следеће године, прелиминарни закључак одржане конференције гласи да у овом тренутку није упутно дозволити рађање људских бића потеклих од генетички едитованих ембриона; у исти мах, готово сви научници се слажу да истраживања, уз највећи разумни опрез, ваља наставити.

 

http://www.radiobeograd.rs/download/Emisije/Solaris/solaris3012.mp3

 

Genome-editing revolution: My whirlwind year with CRISPR

• Jennifer Doudna¹

22 December 2015

Jennifer Doudna, a pioneer of the revolutionary genome-editing technology, reflects on how 2015 became the most intense year of her career — and what she's learnt.

Subject terms:

• Genetics
• Ethics
• Society

 

ago, I started having trouble sleeping. It had been almost two years since my colleagues and I had published a paper¹ describing how a bacterial system called CRISPR–Cas9 could be used to engineer genomes (see ‘Based on bacteria’).

Nature special: CRISPR

I had been astounded at how quickly labs around the world had adopted the technology for applications across biology, from modifying plants to altering butterfly-wing patterns to fine-tuning rat models of human disease. At the same time, I'd avoided thinking too much about the philosophical and ethical ramifications of widely accessible tools for altering genomes.

Questions about whether genome editing should ever be used for non-medical enhancement, for example, seemed mired in subjectivity — a long way from the evidence-based work I am comfortable with. I told myself that bioethicists were better positioned to take the lead on such issues. Like everyone else, I wanted to get on with the science made possible by the technology.

Yet as the uses of CRISPR–Cas9 to manipulate cells and organisms continued to mount, it seemed inevitable that researchers somewhere would test the technique in human eggs, sperm or embryos, with a view to creating heritable alterations in people. By the spring of 2014, I was regularly lying awake at night wondering whether I could justifiably stay out of an ethical storm that was brewing around a technology I had helped to create.

Based on bacteria

How CRISPR–Cas9 works

Clustered regularly interspaced short palindromic repeats, or CRISPRs, are repeating sequences found in the genetic code of bacteria. They are interspersed with 'spacers' — unique stretches of DNA that the bacteria grab from invading viruses, creating a genetic record of their malicious encounters.

On a repeat encounter with a virus, a bacterium can produce a stretch of RNA that matches the viral sequence, using the material in its spacer archive. This 'guide RNA' teams up with DNA-cutting Cas enzymes, encoded by nearby CRISPR-associated genes, to seek out and 'cleave' the matching viral sequences, stopping the virus from replicating.

By engineering the guide RNA, researchers can programme Cas enzymes — most commonly Cas9 — to match the DNA at specific sites that they want to cut in a cell's genome. This triggers a DNA repair that can result in precise sequence changes to the gene of interest.

More

Growing excitement

“I hope you're sitting down because it's unbelievable how well it's working.” That was the verdict, delivered in December 2012, of a colleague who had been experimenting with CRISPR–Cas9. It reflected my own lab's experience, and that of others who had contacted me that autumn to share their excitement about the genome-editing technology.

It often takes years for a new molecular tool to take hold. Yet even before the end of 2012 — just a few months after my colleagues and I had published our initial study — at least six papers describing different uses of CRISPR–Cas9 for genome engineering had been submitted for publication.

In early 2013, several papers, including some describing how the technology could be used to edit the genomes of human stem cells and to alter a whole organism (the zebrafish), were an early indication of the coming tsunami^{2, 3}. By the end of 2014, scientists had — among other things — used CRISPR–Cas9 to enhance pest resistance in wheat, reproduce the carcinogenic effects of specific chromosome translocations in mouse lungs and correct a mutation in adult mice that in humans causes the disease hereditary tyrosinaemia^{4, 5, 6}.

An ethically more complicated potential use of CRISPR–Cas9 was underscored in February 2014, when researchers described how they had used it to make precise changes to the genomes of cynomolgus monkey embryos⁷. (Cynomolgus monkeys are so genetically close to humans that they are commonly used to model human genetic disease.) The monkeys that developed — through implantion of the embryos into surrogate mothers — carried the genetic changes in most of their cells, including their eggs or sperm. This meant that the alterations could be passed down to future generations.

Gene-editing summit supports some research in human embryos

I was alerted to the paper by reporters seeking my comments on the research. After reading the preprint, I gazed out of my office window and across the San Francisco Bay and pondered how I would feel if the next reporter to contact me wanted to know about genome-editing work involving human embryos. “How long will it be before someone tries this in humans?” I wondered aloud to my husband over breakfast the next day.

At the same time, I had been receiving e-mails from people facing potentially devastating genetic predicaments. In one message, a 26-year-old woman told how she had discovered that she carried the BRCA1 mutation, which gave her a roughly 60% chance of developing breast cancer by the time she was 70. She was considering having her breasts and ovaries removed, and wanted to know whether the approaches made possible by CRISPR–Cas9 meant that she should hold off.

The monkey study and interactions with patients or their relatives weighed on me. Every day brought a new influx of papers describing research using CRISPR–Cas9. My inbox was full of requests from researchers seeking advice or collaboration. All this activity could have a direct impact on human life, yet most people I knew outside of work — neighbours, extended family members, parents of my son's classmates — remained largely oblivious. I felt as though I was living in two separate worlds.

Towards the end of 2014, my unease outweighed my reluctance to step into a more public discussion. It was clear that governments, regulators and others were unaware of the breakneck pace of genome-editing research. Who besides the scientists using the technique would be able to lead an open conversation about its repercussions?

The ethics debate

My first serious foray into the ethics was a one-day conference in January in California's Napa Valley, which I helped to organize and which was sponsored by the Innovative Genomics Initiative. Eighteen of us (scientists, bioethicists, a film-maker and an administrator from the University of California, Berkeley) discussed how genome engineering could affect health care, agriculture and the environment. In particular, we talked about issues surrounding the modification of the human germ line — eggs, sperm and embryos.

CRISPR: Science can't solve it

Shortly after the meeting, we published a perspective article in Science⁸ that urged the global scientific community to refrain from using any genome-editing tools to modify human embryos for clinical applications at this time. We also recommended that public meetings be convened to educate non-scientists and to enable further discussion about how research and applications of genome engineering might be pursued responsibly.

Since the Napa meeting, I have given more than 60 talks about CRISPR–Cas9 — at schools, universities and companies, and at some two dozen conferences across the United States, Europe and Asia. I have spoken about it before the US Congress; talked to staff members at the White House Office of Science and Technology Policy, which provides science advice to the US president; and answered questions from the governor of California, among many others. These discussions have pushed me far outside my scientific comfort zone.

I am a biochemist; I haven't worked with animals, human subjects or human tissues, and there was a lot that I didn't know about the ethical difficulties inherent in other areas of research such as cloning, stem cells and in vitro fertilization. I have relied on the generosity of colleagues who have helped to educate me — about how experiments involving human subjects or tissues are regulated in different countries, for example, and how ethical difficulties stemming from in vitro fertilization have been handled historically.

“These discussions have pushed me far outside my scientific comfort zone.”

This year has been intense — and intensely fascinating. At times I have wished that I could step off the merry-go-round, just for a few minutes, to process everything. Ensuring that my travel and other commitments do not disrupt the progress of my lab members has been a priority, but working with them has increasingly involved meeting at night or on weekends, or conferring by e-mail or Skype. For now, time for my beloved vegetable garden and for hikes into the wilds of California with my 13-year-old son is gone.

Almost three years after a colleague warned me that a “tidal wave” of research, discussion and debate involving CRISPR–Cas9 was coming, I still don't know when the wave will crest. But as the year ends, there are some things of which I am sure.

Broadening the conversation

With only 18 attendees — all from the United States and most of whom were scientists — the Napa meeting could only ever be a starting point for a broader conversation. But the meeting, and the commentary that resulted, were important on two fronts.

By mid-2014, I was concerned that CRISPR–Cas9 would be used in a way that was either dangerous, or perceived to be dangerous, before scientists had communicated enough about it to the wider world. I wouldn't have blamed my neighbours or friends for saying, “All this was going on and you didn't tell us about it?” The Science perspective, and a related Comment published in Nature the week before⁹, helped to convey the message that those leading the work recognized that they had a responsibility to voice concerns.

Where in the world could the first CRISPR baby be born?

The discussion initiated by these articles — which grew more urgent when a study was published in April in which CRISPR–Cas9 was used to modify the genomes of non-viable human embryos¹⁰ — also helped to set in motion the multitude of hearings and summits that have happened around the world since. The most prominent of these occurred in Washington DC earlier this month when the Chinese, US and UK science academies co-hosted a meeting on gene editing in humans.

With science now so influenced by international collaboration, scientists can in principle shape the direction of the global scientific enterprise to some extent through self-censorship. It seems obvious to me now that engendering more trust in science is best achieved by encouraging the people involved in the genesis of a technology to actively participate in discussions about its uses. This is especially important in a world where science is global, where materials and reagents are distributed by central suppliers and where it is easier than ever to access published data.

I am excited about the potential for genome engineering to have a positive impact on human life, and on our basic understanding of biological systems. Colleagues continue to e-mail me regularly about their work using CRISPR–Cas9 in different organisms — whether they are trying to create pest-resistant lettuce, fungal strains that have reduced pathogenicity or all sorts of human cell modifications that could one day eliminate diseases such as muscular dystrophy, cystic fibrosis or sickle-cell anaemia.

But I also think that today's scientists could be better prepared to think about and shape the societal, ethical and ecological consequences of their work. Providing biology students with some training about how to discuss science with non-scientists — an education that I have never formally been given — could be transformative. At the very least, it would make future researchers feel better equipped for the task. Knowing how to craft a compelling 'elevator pitch' to describe a study's aims or how to gauge the motives of reporters and ensure that they convey accurate information in a news story could prove enormously valuable at some unexpected point in every researcher's life.

 

 

 

 

 

 

 

 

 

 

 

 

[Џуманџи]

7 ways CRISPR is about to change our world

 

It will strengthen food crops

Scientists can eliminate anything from unwanted browning in mushrooms to weaknesses in food crops prone to bugs and disease using CRISPR and that could make it one of the the most quickly adopted technologies to ever hit the food industry as CRISPR’d food could up production while eliminating the need for harmful pesticides.

The USDA has already said it would not regulate CRISPR’d food. However, it’s unclear how the public will receive it. There’s already a lot of backlash against genetically modified foods. However, CRISPR’d food isn’t genetically modified, it is genetically snipped — meaning no genes from potentially harmful species are added to the crops. Instead, genes are simply snipped out using the Cas9 enzyme.

 

It could cure cancer

Using CRISPR on humans is still very controversial but the gene-editing tool could improve cancer immunotherapy or even cut out the gene-causing cancer cells before they start wreaking havoc on your body.

In 2016, the National Institutes of Health green lit a study involving CRISPRing out three different kinds of cancers on humans.

The small trial was funded by none other than famous internet billionaire Sean Parker and spearheaded by scientists at the University of Pennsylvania.

However, we won’t know the results for quite some time as the study is still waiting on approval from the FDA.

 

Wipe out Zika-carrying mosquitos

While science has a few tricks to eradicating the Zika-carrying Aedes aegypti mosquito, CRISPR could single-handedly kill the species in one generation.

We certainly have the technology to do this right now, but the idea is controversial. One argument against it is that it could create an unforeseen ecological disaster. We don’t fully understand the role mosquitos play in the environment (if any) but simply wiping them out without knowing could have dire consequences.

Of course, the flip of that Aedes aegypti is not native to North America and it would be okay to get rid of them.

Another argument against using CRISPR to wipe out the bug is that it could inadvertently create a super mosquito immune to the technique or that the defective mosquito DNA could somehow jump to other insects and cause an ecological disaster.

 

Engineer better drugs

CRISPR could give us more targeted drugs with the ability to modify cells within the body.

Last year, Bayer struck a deal with CRISPR Therapeutics, the startup founded by one half of the pioneering team that discovered the Cas9 technology Emmanuelle Charpentiere, to create drugs using the technology.

Other drug companies soon followed, opening the door to creating better drugs for rare, inherited diseases and creating a revolution in the pharmaceuticals industry.

 

Heal the blind

Late last fall, scientists released the first study showing CRISPR could potentially heal the blind. The gene-editing tool was used in rats to replace faulty genetics causing blindness with a working set of healthy genes.

The study, conducted at the Salk Institute in California, resulted in a partial restoration of sight.

In another study at Columbia University and the University of Iowa earlier in 2016, scientists were able to show they could successfully cure a person born with a genetic defect leading to blindness using CRISPR technology.

Though this was just one person, it demonstrated those born blind or with a genetically inherited disease causing blindness later in life could potentially one day have their vision restored.

 

Eliminate HIV

Right now patients with the deadly virus must use a toxic concoction of anti-retroviral medications to suppress the HIV from replicating and becoming full-blown AIDS. However, a recent study involving mice showed CRISPR/Cas9 can be programmed to chop out any genetic code in the body with scissor-like precision, including, possibly, all HIV-1 DNA within the body. And if you cut out the DNA, you stop the virus from being able to make copies of itself.

The next stage would be to repeat the study in primates and then humans.

 

Snip out genetically inherited diseases before babies are born

This week scientists from Oregon Health and Science University published a paper showing they could successfully use CRISPR to wipe out a genetically inherited heart mutation in human embryos. The embryos were only allowed to grow for a few days, but the technology produced a positive outcome.

This was the first time scientists had used CRISPR on human embryos in the U.S. and the first time scientists could demonstrate CRISPR could produce healthy embryos using the technology — adding to the hope CRISPR could one day be used to wipe out a number of genetically inherited diseases before humans are even born.

Извор: https://techcrunch.com/gallery/7-ways-crispr-is-about-to-change-our-world/