Bacteria were the original forms of life to appear on earth some four billion years ago, while our own tenure on the planet goes back no more than a few million years. With that kind of head start, it should not be surprising that bacteria have developed some impressive biochemical tricks to ensure their very lengthy survival. For our part, we have proved to be adept at turning some of these natural processes to our own advantage, perhaps never more so than when we recently got bacteria to show us how to re-write the fundamental chemical code of all living things. [see “Gene editing gets unrestricted”, below]
The result has been an intricate scientific acronym — CRISPR-Cas9 — that has quickly gained a prominent public profile. The first set of letters stands for “clustered regularly interspaced short palindromic repeats”, while the second part is “CRISPR-associated genes”. That kind of scientific jargon seldom makes its way into popular discussion and debate, yet CRISPR has become the focus of everything from heartfelt hopes of curing inherited ailments to fundamental fears that we will manipulate our biology in some catastrophic manner.
Canadian researchers are joining their colleagues around the world in exploring the potential of this powerful new technique for altering plant and animal genomes. For now, most of this work presents little in the way of ethical or regulatory challenges, but should it begin to concentrate on our own human genetic make-up, investigators in this country could find themselves at a serious disadvantage. Criminal legislation introduced more than a decade ago to govern stem cell research could ultimately hold back the progress of work with CRISPR in Canada should it apply specifically to human health. Earlier attempts to prevent the same challenges from hindering stem cell research proved divisive and controversial, so much so that many observers fear the law will not be amended even if CRISPR shows great promise in treating particular diseases or debilitating conditions.
That prospect was enough to inspire a group that over the past year has been collaborating with Canada’s Stem Cell Network and McGill University’s Centre of Genomics and Policy to mount a series of workshops intended to review government policy around this legislation. These gatherings led to a consensus statement that was published earlier this year, which contains a series of key recommendations for reforming the way gene editing, genetic testing, and reproductive medicine are regulated in Canada.
Vardit Ravitsky, Associate Professor, University of Montreal School of Public Health
“We’re definitely one of the most restrictive in the world right now,” says Vardit Ravitsky, an associate professor in the University of Montreal’s School of Public Health and one of the signatories to the consensus statement. She specializes in bioethics and has spent much of her career dealing with the implications of the 2004 Assisted Human Reproduction Act (AHRA). This law was ostensibly introduced to licence, monitor and inspect the use of technologies such as in vitro fertilization, whether they are used in a clinical setting as well as for research purposes.
The AHRA prohibits activities such as human cloning, combining human and non-human genetic tissue, transplanting a non-human embryo into a human being, or creating an embryo for any purpose other than causing a human child to be born. While some other sections of the law were challenged and in 2010 declared by the Supreme Court to be beyond the constitutional scope of federal government powers, a violation of these remaining parts of the statute can bring a fine of $500,000 or a 10-year prison sentence. Subsequent governments have not approached the task of trying to amend or update the AHRA, which in light of the earlier court challenge might be a difficult process.
“The promised review of the provisions and operations of the AHRA a few years following enactment did not occur,” says the consensus statement. “Since 2004, considerable advances in human reproductive medicine and genetics research, with implications for selection and modification in humans have occurred.”
For Ravitsky, that means Canada’s rules for genetic editing are in limbo just as we are learning how much might be accomplished with the biochemical tools now at our disposal.
“It is clear that in most countries, to make a baby that has been genetically edited at that early stage would be illegal,” she acknowledges. “But what we’re looking at is to use it as a research tool. We’re not even thinking about reproductive use at this point. We’re just at the stage where we can use CRISPR in the lab on germ cells or early embryos just to learn what we can, or to learn whether we can do this safely. We’re years away from being able to even suggest that a procedure like that could lead to an actual pregnancy.”
Although it is easy to imagine the long-term impact of CRISPR, such as correcting genetic flaws that might be responsible for anything from an allergy to a crippling disease, Ravitsky insists we are a long way from knowing how to reach those goals, nor are we any closer to forms of genetic enhancement, an idea that comes freighted with the history of eugenics and the very subjective notion of what it would mean to make a “better” human being.
In the meantime, she adds, researchers are welcoming the investigative power of a new tool and want to make the fullest use of it. Such work already involves the manipulation of germlines, those large collections of plant and animal cells that can reproduce and pass along genetic changes made in laboratory. While most of these activities face no more regulatory hurdles in Canada than they do in other parts of the world, at some point researchers here may need to start looking at human germlines, a move that would then butt up against the severe legal strictures of the AHRA.
“Researchers tell us that the differences between the human germline and the animal germline are such that at some point we’re going to have to include humans because there’s a limit to what we can learn from animal models,” says Ravitsky, who notes that whether this work will be legally permitted remains entirely unclear. “This law was never meant to regulate research or to create barriers to scientific progress.”
Most of the Act’s language revolves around the intention to create a baby, something that does not apply to the current state of the science. The fact that the regulatory structure is rooted in criminal law, with steep penalties that include imprisonment, means that research institutions will be understandably reluctant to venture into this field.
“If a study like this was suggested to the Canadian Institutes of Health Research or Genome Canada, I don’t think they would touch it,” Varitsky argues. “No federal agency would risk funding something that is potentially federally criminal.”
Other observers respond that it is too soon to begin worrying about such roadblocks. Janet Rossant, a senior scientist in developmental and stem cell biology at Toronto’s Hospital for Sick Children, maintains that the roots of this work date back all the way to the dawn of agriculture, when we first began breeding particular plants and animals to suit our needs, an extremely elementary form of genetic modification.
“We are moving from looking for natural selection to do the job for us to being able to understand more about genes and being able to direct genetic changes much faster than we could do by the old selective processes,” she says. “We’ve been editing in experimental situations quite a lot over the last 20 or 30 years. We can make alterations to the genes of cells in culture. We can do it in mouse embryos and we’ve been doing it for a long time in my lab.”
CRISPR-Cas9, which introduces the ability to remove a specifically selected section from a plant or animal’s genome and replace it with an entirely different arrangement that will then be passed on to the next generation, takes this work to a new level. “You can add in other genes — you can repair genes, you can knock out genes, you can insert things in genes,” Rossant observes. “It is incredibly precise and incredibly efficient.”
Among the most obvious applications of this technique would be creating varieties of crops or livestock that are resistant to particular diseases. Similarly, microbes could be engineered to mass produce desired chemicals or consume particular contaminants. It might even be possible to introduce a fatal genetic modification that makes its way through an entire species, which could lead to the eradication of unwanted pests such as malaria-spreading mosquitoes.
Among the imagined applications for CRISPR technology is the eradication of unwanted pests, such as mosquitoes
Human biology would be no less amenable to such alterations, and researchers are already examining new ways of removing the genetic patterns that cause disorders such as sickle cell anemia or Duchenne muscular dystrophy. Infectious diseases like HIV, which are currently incurable, could be resolved by modifying the body’s immune cells to recognize and permanently remove this virus.
If the benefits to humanity are easy to imagine, however, so too is the unwanted social and environmental upheaval that could accompany the widespread use of this technology. Fears of these negative effects date back to the advent of recombinant DNA work and the discovery of human embryonic stem cells in the 1970s. Although the birth of the first “test tube baby” in 1978 was initially greeted as an ethically dubious milestone, the ensuing enterprise of in vitro fertilization — which enabled large numbers of otherwise infertile couples to conceive a child — became widely regarded as a welcome piece of progress. Less welcome was the birth of a sheep named Dolly in 1996, the first successfully cloned animal and for many, the harbinger of an undesirable reproductive option.
“The precautionary spirit of the law, the conservative take that it has on research, stems from this historical moment in time,” says Ravitsky, who credits the fear generated by cloning for the deliberations with the harsh tone of legislation like the AHRA less than a decade later. The cloning of whole animals — including humans — subsequently proved to be unwieldy and largely impractical, yet the AHRA remains in force, unchanged.
“It’s been decades and nobody has cloned a baby,” she points out. “Can we move on?”
Unfortunately, moving on will require more serious public engagement than has so far taken place. The University of Ottawa’s Institute for Science, Society, and Policy (ISSP) collaborated with the Royal Canadian Institute for Science earlier this year to initiate just such a dialogue with a public panel discussion of the promise and perils of gene editing. As a member of the panel, Rossant noted that it was parliamentary committees acting with public input that had led up to the blunt language in the AHRA. That was almost 20 years ago and she cited a coming need to revisit the subject.
“In Canada we haven’t even started the process,” she warned. “There is going to be a time when we have to go back and look at Assistant Human Reproductive Technologies Act, because we’re going to need a public discussion.”
Another panel member, Jennifer Kuzma, contrasted Canada’s criminal law restraint on human genome editing with its American counterpart, which is not criminal in nature and bans only public funding of such work rather than altogether preventing it from happening. For Kuzma, a professor based at the University of North Carolina who is in Ottawa as the ISSP’s Fulbright Visiting Research Chair in Science and Society, this distinction reflects how each country confronts the scientific desire to employ these tools and the willingness of clinicians or entrepreneurs to put them to practical use.
“You even have an issue with transparency in Canada,” she argued, referring to genetically modified foods being readied for approval with little in the way of open discussion. “There are products that are under review on the animal side and the public isn’t even aware that they’re coming down the pipeline.”
Meanwhile, Canadian scientists are all too aware that human germlines are largely off limits to them. To Ravitsky, whether or not such work ever results in miracle cures is entirely beside the point. She worries more about the fact that our scientific community has no immediate opportunity to use a proven, powerful technique to consider the unique aspects of our own genome.
“We’re missing out on an opportunity to do valuable research,” she concludes, “because we have an ambiguous section in a law that was originally meant to regulate reproduction.”
Gene editing gets unrestricted
The gene editing tool known as CRISPR-Cas9 emerged from research conducted for the dairy industry, which deals in products that rely on bacteria-generated chemical reactions, such as cheese and yogurt. In the 1960s attempts to understand how to keep these bacteria healthy revealed the presence of remarkable molecular manipulation mechanisms called restriction enzymes. Bacteria can wield these enzymes on an invading virus, essentially neutralizing it by selecting key portions of its genetic code and substituting a different section that renders it harmless.
By the 1980s advances in genetic engineering techniques allowed agrobotanists to genetically modify bacteria that could then employ restriction enzymes on particular crops, which in this case would have desirable disease-fighting traits transferred to their genomes. In 2011 this ongoing work singled out a specific protein, Cas9, that could be “programmed” with RNA to seek out and remove a specific DNA sequence in any genome in any organism, then substitute another sequence. Subsequent work has confirmed the open-ended capability of this agent, which is now being tested in laboratories around the world.