CRISPR Cas9 system has been a topic of debate recently as a boon or curse to the genetic community. As recently, the news of genetically modified babies by the Chinese scientist He Jiankui spread like wildfire, and lead to more questions than answers.
What is the CRISPR and Cas9 System?
CRISPR (Clustered regularly interspaced short palindromic repeats, a short RNA) and Cas9 (CRISPR associated protein, nuclease protein) is an antiviral defense system in the prokaryotic cells which works in the CRISPR+Cas9 complex form. When there is a presence of viral DNA in the bacterial cell, the CRISPR RNA from the complex recognizes the viral DNA (due to the presence of some complementary nucleotides on CRISPR RNA for the viral DNA). The nuclease protein from the complex binds to the RNA-DNA hybrid and cleaves the viral DNA and not the CRISPR RNA. This system is naturally present in the bacterial cells, however, it has proven to be beneficial to the human beings in gene silencing.
How does it work in humans?
A target DNA in the human needs to be silenced. For this, an RNA (gRNA, Guide RNA) since it guides the Cas9 protein towards the target DNA, is designed which is complementary to the target DNA. When this RNA enters the eukaryotic cell, it cleaves the target DNA, thus silencing those particular genes.
Apart from the ethical questions, CRISPR has raised in society, it has proven to be a precise and efficient tool for gene silencing and manipulation. This time it has proven itself against ‘The Emperor of All Maladies’ and thus giving humanity another ray of hope against it.
CRISPR for Sarcoma and Myeloma
At the University of Pennsylvania, USA, the researchers have conducted trials and treated 2 patients with multiple myeloma (Kahler’s Disease) and sarcoma (cancer in the connective tissue) using CRISPR based therapy. This study is the first instance of patients being treated with CRISPR based technology.
The project lead, oncologist Edward Stadtmauer, mentions that CRISPR is going to an effective tool in immunotherapy. The overview of the technique involves – filtration of T Cells from patients with cancer, using gene editing technique knocking out 3 of the cells of the existing receptors and insertion of a gene for the receptor NY-ESO 1 using a lentiviral vector. These modified cells are then grown in the lab for a few weeks. They are infused back into the person after a brief course of chemotherapy.
Apart from cancer, there are other researches going on ex CRISPR editing to cure blood disorders like Beta Thalassemia, Sickle Cell, and other genetic disorders.
CRISPR for Non-Small Lung Cancer
At Sichuan University, China there have been trials for silencing a gene PD-1, which is an immune checkpoint gene. This gene suppresses the T Cell inflammatory activity. Some types of cancer overtake this system to undergo uncontrolled growth and this leading to tumors. During the trial, the edited T Cells are injected back to the body and expected to attack the other infected cells. The first injection was found to be successful with 6 months of observation.
Apart from the ethical perspective, the CRISPR Cas9 System has proven itself as a pioneer in genetic editing. Since the system is naturally built in the prokaryotes, its application is hassle-free. Apart from cancer and immunotherapy, there are many trails going on worldwide testing the full potential for this system.