Delving into the Extraordinary Power of CRISPR: How does it Work?

By Andrew Yang

CRISPR-Cas9: When the target sequence is located, CRISPR’s Cas9 protein acts like molecular scissors and removes the problematic target DNA. Image courtesy of Shutterstock.

Imagine a world where genetic conditions are permanently treated, hunger is solved by developing more resilient crops, and species extinction is a thing of the past. This is no sci-fi fantasy, but the promise of CRISPR, the leading genome-editing technology that has captured the interest of scientists and innovators. CRISPR, as we know, has the power to dictate the future, offering unique and extremely efficient solutions to persisting problems. But let’s take a step back and examine what CRISPR is and its contributions today.

So how does CRISPR work? Think of the genome of every living organism as a lengthy essay, composed of a vast number of letters. Each letter represents a nucleotide, the building blocks of RNA and DNA, which genetically make up all living organisms. While you’re scanning the document for mistakes, you come across a typo—a potential life-altering genetic disease. Just as you would normally correct the word by deleting the letter and replacing it with the correct one, CRISPR acts similarly. Using a “guide RNA” as the navigator, CRISPR locates the specific sequence of DNA that needs to be repaired. When the target sequence is located, CRISPR’s Cas9 protein acts like molecular scissors and removes the problematic target DNA. From here, scientists can provide a template to help add the correct fragments of DNA to replace the faulty ones, effectively rewriting the genetic code.

CRISPR stands for “Clustered Regularly Interspaced Short Palindromic Repeats”. In essence, it’s a tool that lets scientists edit DNA freely. But CRISPR wasn’t invented in laboratories—it was actually discovered in bacteria. For millions of years, these microorganisms have utilized CRISPR to protect themselves from viruses. But how did CRISPR get its name? The “Clustered Regularly Interspaced Short Palindromic Repeats” involves a section of bacterial DNA that consists of two parts: the repeats and spacers. Repeats are short, identical DNA sequences that are palindromic because their sequence reads the same forward as backward, like the word “race car”. Spacers are these unique bits of DNA from viruses that have attacked before, that sit between the repeats and are stored in this DNA archive to memorize past encounters with viruses and to help defend against future attacks. In essence, bacteria have an incredible defense system where they’re able to store fragments of viral DNA, creating a molecular memory to help recognize and shut down future viral attacks. Inspired by this, scientists wanted to repurpose this natural mechanism to help redefine genome editing. Jennifer Doudna and Emmanuelle Charpentier, pioneers of contemporary genome editing, have adapted CRISPR to precisely manipulate DNA in any organism, opening a realm of new possibilities. For example, scientists are currently utilizing CRISPR technology to treat sickle cell anemia by either editing the mutated gene that produces abnormal hemoglobin or reactivating a gene that will produce healthy hemoglobin in the bone marrow. Currently, numerous clinical trials have been performed with significant success.

Although the future is quite vast with CRISPR, its application in humans inherently raises important ethical questions. We know that CRISPR can permanently change the genetic makeup of a living person. However, CRISPR can be applied to germline cells, enabling genetic changes to be passed down to offspring. This could pave the way for “designer babies”, who might possess enhanced abilities like boosted intelligence or athleticism through germline editing. This prospect raises ethical dilemmas about whether we humans should be “playing God”. As more breakthroughs occur in biomedical research, we start to harness enough power to breach the natural boundaries of life, altering what some say should not be touched by humans. Additionally, these revolutionary procedures do not come without a price. With potential costs of hundreds of thousands of dollars for a single procedure, it raises concerns such as who can truly afford these procedures and whether only the rich will benefit from these breakthroughs. This lack of equitable access could potentially widen the gap between the wealthy and poor, putting some communities at an even greater disadvantage.

CRISPR has allowed us to step into the foreign grounds of genome editing. We’ve unlocked the ability to rewrite genetic code, giving us the power to cure genetic diseases and address even the most pressing problems in the present world. Its massive potential to cure diseases like sickle cell anemia marks it as a huge leap in the medical field. While we venture out into the unknown, we should exercise caution and proceed responsibly while considering ethical concerns. CRISPR’s potential to revolutionize treatments and address global challenges is exciting, marking it as a major step forward in science and medicine, unlocking once unimaginable possibilities.