Just imagine that in a few years we’ll be able to cure cancer. And AIDS. Alzheimer’s. Diabetes. Huntington’s Disease. Colour blindness. Haemophilia. Trisomy 21 – all that with a little injection from your family doctor. What sounds impossible now could become reality in the near future, thanks to the new star in the world of medical research, the Crispr/Cas9-System. Crispr allows the editing of genes, creating the possibility of fighting genetic diseases. Crispr Technologies, based in Basel, does research with this newly discovered miracle cure.
Cris – what?
Emmanuelle Charpentier (Co-founder of Crispr Technologies) and Jennifer Doudna made their key discovery only a few years ago. While examining the immune system that bacterias use against viruses, they stumbled upon Crispr. They were able to find DNA fragments of hostile viruses in the genotype of especially-resistant bacterias. They noticed that if a virus finds its way into a bacterium, parts of the hostile genetic code are inserted into the genome of the bacterium, a sort of “recollection of former genetic attacks”.
This insertion results in the bacterium saving a part of the virus-DNA in their own genetic code in a DNA-archive. The DNA-archive that holds all hostile genetic segments is called Crispr: Clustered Regularly Interspaced Short Palindromic Repeats. The inventor of the name now feels that had he had any idea what was going to happen with this research, he would have come up with a simpler name. But for now, it’s just Crispr.
If the virus attacks again, a protein called Cas9 becomes active. It scans the bacterium in search of the virus, while comparing every bit of DNA to the sample from the Crispr-archive.
If it finds a perfect match, it cuts out the virus-DNA and protects the bacterium from the attack.
And it gets better – Crispr is programmable
The real revolution started when researchers found out that the Crispr/Cas9-System is programmable. You can give it a copy of the DNA you want to modify and put the whole system into a living cell. There, Crispr finds the desired part of DNA and the Cas9-protein changes whatever portion of the DNA you want to adjust.
Think of Crispr as a GPS-system that is able to locate a desired string of DNA inside a cell. The Cas9-protein acts as the scissors that cut out the wrong genetic segment and substitute in the proper one. Although Crispr and Cas9 are originally used by bacterias, the system works for every type of cell; microorganisms, plants, animals and even humans. In addition, Crispr offers the ability to edit living-cells.
Wait a moment before hanging up your “we kicked cancer’s ass!” banner
The research is still very much in its infancy. Although Crispr is already more exact than all lab tools before, it is still not absolutely accurate yet. In rare cases, the Cas9-protein cuts genes that shouldn’t be transformed. It functions a lot like autocorrect with a written text: Switching a unique word is no problem (“Genothype” to “Genotype”), but a change in frequent letter combinations (“Sun” to “Suhn”) results in numerous words suddenly changing: Suhnshine, Suhnday, suhndering. Researchers call this “off target”. In the worst case scenario, the supposedly life-saving therapy can cause cancer.
Crispr’s very own curiosity cabinet
When it comes to animals and plants, gene editing is a well-established process. Agricultural companies frequently experiment with wheat and maize varieties to create strains that are resistant to pests. Just recently, the U.S. released the first Crispr-edited mushroom into the market. Its genes were manipulated to make the mushroom resistant to turning brown. Chinese researchers have managed to breed minipigs with Crispr, whom they want to sell as domestic animals. They’ve switched off the gene responsible for the growth of the pigs. The animals now reach only one third of the size of their natural relatives. A geneticist at the Harvard University wants to create elephants similar to mammoths, while inserting genes of the extinct species into the genome of the pachyderm. However, these are only strange side scenarios. More important are all the illnesses that doctors want to cure with gene-editing.
… but let’s stick to the essentials
The main enemy being targeted is AIDS. Typically, AIDS drugs suppress the increase of the virus and thus delay the outbreak of the illness. However, the infection itself is still not curable.
The battle against AIDS won’t be a simple one. HIV integrates its own genetic information into human immune cells. As part of the human genotype, it is safe from immune system attacks, because the system can’t identify it as an enemy. Researchers are now trying to close the gap through which the virus enters human immune cells. Their plan of attack is to cut the gene that contains the construction plan of the molecules to which the HIV attaches itself. With this method, scientists only have to extract stem cells from a HIV-infected person, add Crispr/Cas9 to it and inject the transformed cells back to the patient.
This HIV therapy already works on mice. There, scientists were able to turn off the portion of the DNA that created the HIV attaching points, without the stem cells losing any of their functions. These learnings about what works on rodents are now being transferred to human cases. Researchers are optimistic that in two to three years, they’ll attempt to tackle the first clinical studies with HIV-positive patients.
Evolution won’t be influenced
Along with many other scientists in the world, Crispr Technologies is continuing research with this new method. At this point, experiments are only performed on somatic cells and not on germ cells, meaning that neither sperms nor ova are being altered. This ensures that genetic changes can’t be passed on to the next generation, thereby influencing human evolution. We’ll see to what extent Crispr will help cure genetically conditioned illnesses.
Crispr Technologies is currently doing research in editing the genetic code to cure sickle cell disease. Cancer research is done as well; immuno-oncology attempts to improve our immune systems, making them more capable of recognising and destroying cancer cells. Haemophilia is also being researched to discover a cure.
This discovery will bring about many new conversations because it opens doors of science that were closed up to now. Whether we want to or whether we should open these doors must still be decided. However, one can look forward to the results the research will bring to light and I bet, in a few years time, no one will think about a chips brand anymore when hearing the name Crispr.