CRISPR-Cas9: The ultimate tool for all biological problems or biggest threat to future life?

by Michael Brunner

Even though the discussion restarted with the discovery of CRISPR-Cas9 it is actually about gene editing in general. CRISPR is just the newest technology making genome editing easier and faster than before. Gene editing refers to modifications in the genome of a living organism and CRISPR-Cas9 is by far not the first system that allows modification of DNA in all sorts of organisms.

What is CRISPR-Cas9 and how does it work?

CRISPR is short for “clustered regularly interspaced short palindromic repeats”. These CRISPR patterns are the basis of a primitive bacterial immune system used to remember the DNA of viral invaders. Therefore, the DNA sequence of the virus is incorporated within the CRISPR patterns. The Cas9 protein is later able to recognize the DNA sequence and cuts any DNA molecule with matching sequence. Jennifer Doudna and Emmanuelle Charpentier, who discovered CRISPR-Cas9 in 2012, were the first to use this mechanism to modify the genome.  The system, when equipped with the right guiding RNA can cut and insert any desired DNA sequence. It acts like a molecular scissor and is much simpler and faster than earlier methods which makes this technique so versatile.   

Where can gene editing tools be implemented and what potentials do they harbor?

In Agriculture gene editing is already in use to speed up the breeding process of plants. With the world facing a population increase, the demand for food is on the rise. Through genetic modifications, tolerance of plants to biotic or abiotic stresses can be increased leading to higher yields. CRISPR-Cas9 was even shown to be a precise tool to enhance yield, quality and nutritional value of different plant species. Therefore, it can contribute to food production for the benefit of a growing human population. Using gene editing new features could be added or removed, for example by making spicy tomatoes or gluten-free wheat.

CRISPR has quickly risen in popularity as a tool in Biomedicine since it offers immense therapeutic potential for the treatment of all kinds of human diseases. Advances in gene editing tools allow not only targeting monogenic diseases, but also polygenic diseases such as cancer and diabetes. There are two main approaches to use CRISPR as a therapy: First ex vivo gene editing were human cells are extracted, engineered in the lab and reinjected into the patient. This method is already in use for most gene therapies but is quite expensive since each patient requires an individual manufacturing process for their therapy. The US company eGenesis for example is using CRISPR to modify the pig genome so that their organs can be transplanted into humans without rejection.  Another method is in vivo gene editing were CRISPR-Cas9 is directly injected into the patient’s body to edit the DNA directly from within the cells. This method has only started human testing in 2020.

Risks and ethical boundaries of gene editing

Using CRISPR-Cas9 as a gene editing tool to cure diseases and improve food security is only one side of the medal. The other side can be far more dangerous to people and nature. Using CRISPR-Cas9 to edit human’s genome can lead to a society in which people who do not fit into the medicinal norm are edited in order to do so. Doudna herself has admitted that the technology carries “great risk”. In a New York Times interview on October 22, 2020, she warned of the unknown consequences of embryo editing. There are reasonable worries that the use of these “gene scissors” will in the future cut out extraordinary people without others even noticing. In the eyes of some people, gene editing gives us the power to design better humans and improve future society. But with limiting the gene pool by editing people’s genes comes great risk. So far nobody knows which consequences will arise if we use gene editing in a broad manner. Do we know enough at this point to be sure to not make damages for the individuals to which gene editing is applied? How will future generations be affected?

Genome editing is a powerful technology that can reshape medical treatments and curing of diseases, but it can also reduce human diversity and increase social inequality. By editing out that kind of people who medical science categorizes as diseased or genetically contaminated, diversity is decreased making society less resilient. What is necessary to know about the effects and when does it make sense to use gene editing? This is a question that should be addressed worldwide. To avoid misuse and make sure risks are minimized, a worldwide law is needed defining where the use of gene editing is allowed and where not.

The controversial offer of gene editing to achieve the best kind of people at the genetic level is an uneasy alert to those who are often judged to be biologically inferior. It is complex, highly subjective and context-dependent to evaluate the quality of life of another person. Especially based on the concept that all people are of equal value regardless of individual differences. Expanding diversity in all its forms strengthens the human community ethically and biologically.

 For this blogpost inspiration and information was collected at:

https://www.labiotech.eu/in-depth/crispr-cas9-review-gene-editing-tool/

https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1007994

https://www.labiotech.eu/interview/crispr-therapeutics-genome-editing/

https://genomebiology.biomedcentral.com/articles/10.1186/s13059-018-1610-2

 https://www.frontiersin.org/articles/10.3389/fpls.2020.00056/full

https://www.scientificamerican.com/article/the-dark-side-of-crispr/