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We must keep using CRISPR-Cas9 technology

Today we released a joint statement with other medical research funders in support of research using gene editing techniques such as CRISPR-Cas9 to advance our understanding of disease in preclinical research and to explore their potential for future therapeutic use. Here our Director of Science Programmes Dr Rob Buckle discusses the huge potential of gene editing, and why any attempt to use it in a therapeutic context must be the subject of the kind of intense and rigorous debate that the scientific community and UK regulatory system has demonstrated in the past.

Wooden blocks with DNA letters on them

(Image: Duncan Hull on Flickr under CC BY 2.0)

 

Being able to edit the human genome is not a new idea or capability. For decades researchers have been developing potential gene therapy techniques to correct missing or faulty DNA and restore healthy gene expression in cells.

More recently, techniques have been developed that can edit the genome in a much more efficient and targeted fashion, and one such example, CRISPR-Cas9, has accelerated the field to such an extent that researchers can now make precise edits to the genome in a relatively easy, speedy, precise and error-free way.

The key to CRISPR-Cas9 is its flexibility. It works by combining a piece of RNA designed to match a specific section of DNA with a nuclease enzyme which can cut out the target DNA and paste in the desired sequence.

It can be used to make specific changes to the genome – as small as one base pair or as large as inserting or deleting entire genes or even multiple genes.

It goes without saying that such a capability has a myriad of potential uses, from lab tool to explore the mechanisms of disease to a way to develop treatments for a range of diseases through gene or cell therapy. In principle, the technique could also be used to correct faulty genes in eggs, sperm or embryos and rid a family of a genetic disease forever.

But there are distinctions to be made here: firstly between the use of CRISPR-Cas9 for basic research in the lab and its use with the aim of preventing or treating disease; and secondly between applying the technology to somatic (non-reproductive) and reproductive human cells.

In and of itself, genome editing such as CRISPR-Cas9 does not present any new ethical issues over and above other ways of modifying the genome. Its use is subject to existing legislation – if researchers want to use it in somatic cells they are regulated by the Human Tissue Authority, and if they want to use it in germ cells or human embryos up to 14 days old, they’ll be regulated by the HFEA.

In the lab

CRISPR is already being put to use by hundreds of researchers around the world, including many funded by the MRC.

One such approach is being pursued at the MRC Weatherall Institute for Molecular Medicine in Oxford, where researchers are using CRISPR-Cas9 to edit the genomes of human induced pluripotent stem cells to produce new models of human diseases. By creating many edits against a common genetic background, they can observe the effects of precise edits on disease mechanisms.

WIMM researchers are also looking further towards the clinic, using CRISPR-Cas9 to edit faulty genes in patient haematopoietic stem cells found in the bone marrow with a view to developing their use in treating blood disorders such as sickle cell disease and thalassaemia. One day it might be possible to remove cells with faulty DNA, edit that DNA with CRISPR-Cas9, and transplant these newly healthy cells back into the body.

In a different direction, there is also major interest in applying this technology to CAR-T cell therapy, which is one of the most promising new developments for cancer immunotherapy. This approach relies upon genetically modifying a patient’s regulatory T cells to help attack cancerous cells. To date this has been achieved through the use of viruses, although CRISPR-Cas9 technology could offer significant advantages to this procedure. While these represent exciting developments, it should be emphasised that the routine use of such treatments is probably a decade or more away.

Where we stand

Today’s statement lays out our stance on the use of gene editing. We want research using CRISPR-Cas9 to continue, both as a tool for laboratory-based research and for the development of novel therapeutics, as highlighted above. This includes using the technique in pre-clinical research in human eggs, sperm and early embryos, so long as this is justified, scientifically and ethically, and within current UK law, where such research is strictly controlled.

But we also want open and widespread discussion among scientists, ethicists and the public about how these techniques could be used in the future to treat and prevent genetic disease – whether through the current drive to develop gene and cell therapies using somatic cells, or looking further ahead to their potential in reproductive cells.

We’ve shown that we have the ethical and regulatory wherewithal in this country to find ways forward through complex ethical issues. For example, in recent years, the public, researchers and regulatory systems have come together to find a way forward both in research using human embryonic stem cells and in the use of mitochondrial donation.

Where we go from here

So what are the next steps? The Nuffield Council on Bioethics – to which we provide core funding along with the Nuffield Founcation and the Wellcome Trust – has launched a project on genome editing, in which MRC scientists will be involved. You can read their background paper on genome editing here.

Together with the Wellcome Trust, we’re also funding a meeting of the Hinxton Group, a consortium of stakeholders which works to address ethical issues facing stem cell scientists internationally, to discuss the convergence of gene editing, stem cell research and the potential for modification of human germlines.

In the meantime, we fully support the continued use of gene editing technologies to unravel the complexity of disease and find new ways to treat it. A moratorium is not the answer – the responsible and regulated use of these technologies while their future is openly debated is the way to push the frontiers of science.

Rob Buckle

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