What is the CRISPR technique and what are its applications?

The CRISPR technique is a genetic manipulation tool that allows DNA genes to be altered quickly and precisely. It has great potential in various fields, including the treatment of diseases.

Last update: August 24, 2021

Genetics is the science in charge of studying genes, as well as DNA and RNA molecules. This field has made very important advances in recent years, developing tools that allow the DNA sequences of organisms to be modified. One of the most innovative is the CRISPR technique, which is very easy to use and has multiple applications.

All living things have DNA and RNA molecules, which contain information that determines their characteristics. The information from these microscopic molecules has been the subject of study for many years.

Gene editing is one of the most important achievements in science. In fact, studies affirm that there are several clinical trials on human genes to treat diseases. The application of genetic editing can generate a change in various areas, especially in health.

What is the CRISPR-Cas9 technique?

The CRISPR-Cas9 technique is one of the 3 gene editing tools available today. It is based on the CRISPR regions of bacteria. The word CRISPR is an acronym pronounced as crisper. It comes from the acronym for "grouped and regularly spaced short palindromic repeats."

These palindromic repeats are characterized by having a sequence of nucleotides and spacers. Nucleotides are the basic units that make up a DNA molecule. For their part, spacers are DNA fragments that are sandwiched between nucleotides.

Spacers function as a source of additional information, thus altering the genetics of the organism. A published study establishes that bacteria add viral DNA sequences as spacers for their defense against a specific virus. They allow the creation of specific enzymes that will cut a segment of DNA without altering the genetic information of the organism.

The CRISPR technique for genetic modification was officially created in 2012. It was devised by scientists Jennifer Doudna and Emmanuelle Charpentier. The idea was to create a simple, fast and inexpensive tool that would allow to modify a DNA sequence and introduce changes with great precision.

How does it work?

This method is also known as genetic scissors or genetic copy-paste and its mechanism of action is very simple. It can use multiple enzymes, although the most commonly used is Cas9. An RNA molecule encoding the Cas9 enzyme and a guide RNA must first be introduced into the cell.

The guide RNA will tell the enzyme the specific segment of DNA to cut. The cut is carried out with extreme precision, just as it happens inside the bacteria. Specialists must also introduce the DNA sequence to be inserted into the cell.

After DNA cutting, the cell will initiate the genetic repair process and introduce the desired sequence to the backbone. The inserted sequences are created in specialized laboratories, however, they retain the name CRISPR in honor of the bacterial mechanism.

"Cutting" DNA has proven useful to initiate research that promotes the genetic management of diseases.

What can the CRISPR-Cas9 technique be used for?

The possibilities offered by gene editing are unimaginable. They can range from correcting faulty genes and eradicating disease to producing more resistant crops. LThe CRISPR technique does not currently have a specific application, therefore it is only used in the field of research.

Many laboratories have used this tool to study different phenomena and learn all their mysteries. CRISPR-Cas9 has been used to create transgenic plants and study stem cell reprogramming. It has also been used to gain an in-depth understanding of certain diseases, such as schizophrenia.

One of the fields where this technique can be used is biomedicine. It can be a useful tool to treat and prevent diseases that alter a single specific gene. These genetic scissors would also help in cancer therapies.

Among the possible uses proposed by the researchers, the following stand out:

  • Creation of crops that emit less pollution.
  • Realization of transplantable organs, tissues and cells from animals.
  • Manufacture of new enzymes resistant to temperature changes.
  • Growing grass for cows easier to digest.
  • Treat diseases transmitted by viruses, such as HIV.
  • Prevent the transmission of inheritable diseases.
  • Create antibacterial products with a greater spectrum of action.

What drawbacks can there be?

One of the main limitations of the application of the CRISPR technique is the cutting of DNA outside the target gene. Studies affirm that off-target effects are likely in up to 50% of cases. These unwanted cuts can have serious consequences, and even turn healthy cells into cancerous ones.

In some cases, guide RNAs and modifications made to DNA can induce apoptosis, that is, cell death. For its part, it is also possible to develop an immune response to the Cas9 enzyme.

Introducing CRISPR into the human body is a great challenge. Some of the viruses used in the art can have an affinity for various cells, so they can affect unwanted tissue and cause cellular changes.

Moral problems have also delayed the clinical application of gene editing in general. Some researchers have raised concerns about inappropriate use. It is stated that they can be used to generate people with specific characteristics instead of curing diseases.

Genetics also has more dubious sides and even ethical implications that must be overcome in order to move forward.

Human clinical trials

Until now, human clinical trials with the CRISPR technique are very limited and they are carried out in small populations. One of the first experiments generated great controversy worldwide. The same occurred in 2018 when the Chinese scientist He Jiankui announced the birth of 2 twins resistant to the human immunodeficiency virus (HIV) modified with CRISPR-Cas9.

This study was published in a specialized journal in China, however, the controversy appears due to the possible long-term adverse effects. Furthermore, He Jiankui ignored all the concerns of the international community regarding the alteration of the germ cell line.

Meanwhile, another human clinical trial conducted in China used the CRISPR technique to treat lung cancer in 12 patients. The experiment consisted of altering the patients' T lymphocytes for their subsequent inoculation. None of the treated patients developed adverse effects, although the study is in phase 1.

Around the world there are dozens of human clinical trials with CRISPR. In addition, multiple studies conducted in vitro have shown promising results in the treatment of diseases. However, the technique still needs to be refined.

A technique that needs to be perfected

The CRISPR technique is one of the most revolutionary scientific discoveries of recent years. It allows to cut specific segments of the DNA chain and modify the characteristics of a cell. The many applications could generate great advances in various fields, especially in medicine.

Unfortunately, it has multiple limitations that have slowed its use on a large scale. In this sense, researchers must conduct more studies and refine the technique before it can be used in humans and exploited to its full potential.