Teach Me CRISPR!

Christopher — a young microbiologist and diligent PhD student, was diligently working on his dissertation at one of the institutes in Vienna. His topic was the mechanisms of bacterial immunity. But later, somewhat unexpectedly, in this work he managed to glimpse enormous potential for practical application — so large that it spilled over into a multi-million patent. There was also an ugly story about the distribution of funds — according to Austrian law, the patent owner is the scientific institution, i.e., the institute, but the scientific supervisor, Ms. Dudna, did not like this and she even changed countries to receive royalties in full... But whatever the case, this is the case when your dissertation becomes not just megabytes on a hard drive, but literally — a part of humanity’s future.

It was Christopher himself who directly created and continues to create those mutants, or rather CRISPRs, on various models — starting from plants, mice, and fish, ending with Tasmanian devils and lines of human stem cells. Here is how he draws up the secret mixture in a micro syringe, performs a tiny injection (and usually more than one), and voilà — officially you are GMO :) But more on that later.

And in seriousness, these technologies promise effective treatment for seemingly incurable diseases just yesterday.

What exactly are CRISPR technologies and how do they relate to bacterial immunity?

Bacteria — tiny single-celled organisms with an immunological arsenal they cannot afford to wield as you or I do. But still, as it turned out, we have much to learn from them!

Why do bacteria need immunity and whom do they protect themselves from? For example — from viruses. And although the flu virus does not attack bacteria, there is a whole army of viruses that attack bacteria, called bacteriophages.

When a virus enters a cell, it tries to insert its DNA into the bacterium’s DNA — to use its resources for replication. And the bacterium, in turn, tries to get rid of that misfortune. And while the virus is being inserted into its DNA, it reads and integrates that viral DNA into special regions in its chromosome that have this curious name — CRISPR, or we also call them CRISPRs. A characteristic feature of them is palindromicity (this is when the DNA reads the same on both sides, like < < Kozak from tales > >). In essence, CRISPRs are regions of DNA that the bacterium can read easily (precisely thanks to recognizing those repeats that read the same backward and forward) and learn what kind of illness attached to it.

At the CRISPR region a RNA molecule is synthesized, which is basically a photoreport of the criminal — the viral DNA. And then the tough, “fierce” Cas9 agent (well, 007-ish), that is a caspase (an enzyme that cuts DNA) together with that photoreport organize a search of the bacterial DNA for the presence of fragments of foreign viral DNA. When it finds them — it neatly cuts them out and the DNA is once again as good as new.

Scientists observed that mechanism and tried to push CRISPRs and Cas9 a bit further with some other RNA. And it worked! Thus, you can cut out anything from the DNA of a living cell or even a living organism!

Fair to say, besides Cas9 there are a good hundred similar endonucleases Cas. They were known earlier, but it was Jennifer Doudna’s team that drew attention to their potential for making targeted changes in DNA.

What will this give us and when?

This technology opens broad possibilities in many areas, from new methods to overcome antibiotic resistance in deadly bacteria, to treating certain kinds of cancers. But first and foremost, it will enable the treatment of a number of genetic diseases that were previously incurable. To begin with — diseases caused by defects in a single gene. Today there are about 6,000 diseases of this type. For example, phenylketonuria (many of us learn about it from product labels that say such patients should not eat certain foods. It is the inability to metabolize the amino acid phenylalanine. According to statistics — such a diagnosis occurs in 1 in 12,000 newborns. Or Huntington’s disease and sickle cell anemia — when erythrocytes, instead of a round biconcave shape, become sickle-shaped — hence the name, leading to systemic disturbances of varying severity; as of 2015 — such a diagnosis affects more than 4 million people worldwide.

It is fair to admit that the pipeline of the therapeutic CRISPR technology is not yet there, but given the rapid pace in this direction, one can suppose its availability in the coming 5–10 years for ordinary people, at least in the USA or the United Kingdom.

Currently, this technology is developing purely behind laboratory doors. The results of the first such experiments on editing the human genome, conducted by Chinese scientists, were met with a wave of condemnation — leading scientific journals had to decline publishing materials for ethical reasons. Nevertheless, British scientists recently received permission to conduct experiments involving CRISPR-Cas9 technologies on human embryos in vitro (in a test tube).

In Ukraine CRISPRs are also here. At the Institute of Molecular Biology and Genetics of the National Academy of Sciences of Ukraine, at least three departments actively work with this system. Both in human and in animal cells.

The question of the possibility of genome correction is a very acute one in society — many people still fear GMOs and mistakenly believe that such manipulations are the path to a zombie apocalypse and the creation of dreadful mutants, forgetting the possibilities of curing millions of patients.

Of course, there is an open ethical question concerning experiments on human embryos. Here one can only note that modern approaches and technologies allow minimizing the scale of such trials and reducing them to a minimum.

But yes, here one must make a difficult choice. We pay a huge price for the principles of humanity and progress in medicine, because even decades ago carriers of less successful genetic combinations were doomed to death; today a large part of them survive, have offspring, and pass on their genes. Therefore a reasonable correction of our genome — very soon — is not a whim, but a necessity for the health and prosperity of our species.

In the photo — Christopher Chilinski, source: https://bit.ly/2FHQoGk