Two scientists won the Nobel Prize in Chemistry for developing a method of genome editing likened to molecular scissors that offer the promise of one day curing inherited diseases and even cancer.

Emmanuelle Charpentier, who is French, and American Jennifer Doudna have discovered one of gene technology’s sharpest tools: the CRISPR/Cas9 genetic scissors. Using these, researchers can change the DNA of animals, plants and microorganisms with extremely high precision. This technology has a revolutionary impact on the life sciences. It is contributing to new cancer therapies and may make the dream of curing inherited diseases come true.

Charpentier, 51, and Doudna, 56, became the sixth and seventh women to win a Nobel for chemistry, joining Marie Curie — who won in 1911 — and more recently, Frances Arnold in 2018. It is the first time since 1964, when Britain’s Dorothy Crowfoot Hodgkin alone won the award, that no men are among the chemistry prize winners.

What is genome editing?

In 1953, J.D. Watson and F.H.C. Crick reported the molecular structure of DNA. Ever since, scientists have tried to develop technologies that can manipulate the genetic material of cells and organisms. 

Genome editing (also called gene editing) is a group of technologies that give scientists the ability to change an organism’s DNA. These technologies allow genetic material to be added, removed, or altered at particular locations in the genome. 

Several approaches to genome editing have been developed. A recent one is known as CRISPR/Cas9, which is short for clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9. 

With the discovery of the RNA-guided CRISPR/Cas9 system, an easy and effective method for genome engineering has now become a reality. The development of this technology has enabled scientists to modify DNA sequences in a wide range of cells and organisms. Genomic manipulations are no longer an experimental bottleneck. Today, CRISPR/Cas9 technology is used widely in basic science, biotechnology and in the development of future therapeutics. 

How the two scientists developed CRISPR/Cas9 genetic scissors?

During Emmanuelle Charpentier’s studies of Streptococcus pyogenes, one of the bacteria that cause the most harm to humanity, she discovered a previously unknown molecule, tracrRNA. Her work showed that tracrRNA is part of bacteria’s ancient immune system, CRISPR/Cas, that disarms viruses by cleaving their DNA. Charpentier published her discovery in 2011. 

The same year, she initiated a collaboration with Jennifer Doudna, an experienced biochemist with vast knowledge of RNA. Together, they succeeded in recreating the bacteria’s genetic scissors in a test tube and simplifying the scissors’ molecular components so they were easier to use.

In an epoch-making experiment, they then reprogrammed the genetic scissors. In their natural form, the scissors recognise DNA from viruses, but Charpentier and Doudna proved that they could be controlled so that they can cut any DNA molecule at a predetermined site. Where the DNA is cut, it is then easy to rewrite the code of life. 

Since Charpentier and Doudna discovered the CRISPR/Cas9 genetic scissors in 2012 their use has exploded. This tool has contributed to many important discoveries in basic research, and plant researchers have been able to develop crops that withstand mould, pests and drought.

In medicine, the genetic scissors are contributing to new immunotherapies for cancer and trials are underway to make a dream come true – curing inherited diseases. Researchers are already performing clinical trials to investigate whether they can use CRISPR/Cas9 to treat blood diseases such as sickle cell anaemia and beta thalassemia, as well as inherited eye diseases.

They are also developing methods for repairing genes in large organs, such as the brain and muscles. Animal experiments have shown that specially designed viruses can deliver the genetic scissors to the desired cells, treating models of devastating inherited diseases such as muscular dystrophy, spinal muscular atrophy and Huntington’s disease. 

However, the technology needs further refinement before it can be tested on humans.

Why do genetic scissors require regulation?

Alongside all their benefits, genetic scissors can also be misused. For example, this tool can be used to create genetically modified embryos. 

However, for many years there have been laws and regulations that control the application of genetic engineering, which include prohibitions on modifying the human genome in a way that allows the changes to be inherited. Also, experiments that involve humans and animals must always be reviewed and approved by ethical committees before they are carried out.

It has already raised serious ethical questions in the scientific community. Most of the world became more aware of CRISPR in 2018, when Chinese scientist Dr. He Jiankui revealed he had helped make the world’s first gene-edited babies, to try to engineer resistance to future infection with the AIDS virus. His work was denounced worldwide as unsafe human experimentation because of the risk of causing unintended changes that can pass to future generations, and he is currently in prison.

In September, an international panel of experts issued a report saying it is still too soon to try to make genetically edited babies because the science isn’t advanced enough to ensure safety, but they mapped a pathway for any countries that want to consider it.

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