Nordic Life Science 1
paper they concluded that there was “considerable
potential for gene-targeting and genome-editing applications”. Now, just eight years later, their discovery has literally reshaped life science. ”This is an excellent example of how basic science research on RNA in a humble bacterium could facilitate crucial development of biotechnologies, and ultimately treatment of diseases. The technology is now used in almost every scientific field, ranging from basic to translational research,” says Edmund Loh, researcher at the Department of Microbiology, Tumor and Cell biology at Karolinska Institutet, and a collaborator and friend of Emmanuelle Charpentier. There are now a number of different CRISPR/Cas systems known and these are divided into two major classes. In the Class 1 systems, specialized Cas proteins assemble into a large CRISPR-associated complex for antiviral defense (Cascade). The Class 2 systems are simpler and contain a single multidomain crRNA-binding protein (e.g., Cas9) that contains all the activities necessary for interference, described the Nobel Committee for Chemistry. The system has been found in around 40 percent of all known bacteria and even 90 percent of all known archaea. Each system has a different protospacer adjacent motif (PAM). This motif is the only absolute requirement for CRISPR to work. n short it works like this. When a researcher aims to edit a genome they artificially construct what is known as a guideRNA (gRNA), which matches the DNA code where the cut is to be made. The scissor protein, Cas9, forms a complex with the gRNA, which takes the scissors to the place in the genome where the cut is to be made. “I think the CRISPR/Cas9 discovery and technology benefit all life science fields. In addition, the background story and discovery could encourage more young people and women to be interested in basic science. Hopefully, the discovery will generate more attention from policy makers such as the government, pharmaceutical industries and philanthropic foundations to focus on and fund basic science research,” says Edmund Loh. Since the discovery the field has exploded with applications and CRISPR has become a cost-effective and convenient tool for many different purposes. It can be used for genome editing (knockouts, knockins, exchange of base pairs, removal of genetic elements, homologous recombination) and gene regulation using CRISPR activation (attraction of transcription factors) and CRISPR inhibition (usage of KRAB repressor). It can also be used for tagging genetic elements, reporters, and for functional studies it is possible to have inducible CRISPR systems. According to the Biomedical Centre at the University of Iceland, it may also be used for dynamic imaging of genomic loci in living cells (comparable to FISH, without the need of cell fixation), and can be used in all cells of all organisms. he development potential of the CRISPR system is also enormous and scientists all over the world are making progress almost every day. Just last year, a person with a genetic condition that causes blindness became the first person to receive a CRISPR/Cas9 gene therapy administered directly into their body. The treatment is part of a landmark clinical trial to test the ability of CRISPR/Cas9 gene-editing techniques to remove mutations that cause a rare condition called Leber’s congenital amaurosis 10 (LCA10). According to Fredrik Wermeling, another very relevant example of recent progress is the SHERLOCK method. “In this method a modified CRISPR system is used to identify in a jiffy if a sample contains a specific nucleotide sequence. This method is used for example to identify if a sample contains SARS-CoV-2 and it can be used as a quick and sensitive diagnostic test.” The possibility to tailor make organs for transplantation is another application that has huge potential to solve many of the challenges related to transplant care. Wermeling says, “A third example is gene therapy for different severe inherited monogenic diseases related to the hematopoietic system, such as sickle cell anemia, beta-thalassemia, SCID and WASP.” Scientists have already started some clinical studies and the initial results look promising, according to Wermeling. “This could hopefully open up for treatments of inherited monogenic diseases affecting other organs, for example cystic fibrosis and Huntingtons disease. In the long run, the possibility to treat more common and more genetically complex diseases, such as cardiovascular diseases and cancer, but also dementia, allergies and autoimmune disease, is of course very appealing. It is however, not as clear how these diseases may be tackled using CRISPR,” says Wermeling. 40 NORDICLIFESCIENCE.ORG