CRISPR, the gene-editing technique that allows scientists to change DNA with remarkable ease, was discovered almost a decade ago by a couple of biologists.
Jennifer Doudna and Emmanuelle Charpentier received the Nobel Prize for Physics last year for their work.
Scientists all across the world have been looking at how the technique may be utilized to treat ailments ranging from sickle cell anemia to HIV since its discovery.
Until far, doctors have treated illnesses using CRISPR by taking part in a person’s cells and using the gene-editing method on the cells in a lab.
Doctors will remove cells called hematopoietic stem cells, which will ultimately transform into red blood cells and other blood cells, in the case of sickle cell anemia, when red blood cells become malformed and fail to function correctly.
They then use gene-editing technology to make modifications to those cells, addressing the genetic flaw that is producing the defective blood cells, and reintroduce the cells into the body.
However, researchers have started experimenting with a novel strategy in recent years: infusing DNA editing technology straight into circulation.
This technique provides several benefits, including the potential to treat a broader spectrum of illnesses with more ease and at a lower cost.
At the same time, other academics are raising concerns about the new approach, noting that it has dangers, such as accidentally altering healthy genes without a reliable means to halt it.
“I believe that every new technology should be approached with caution,” says Qiaobing Xu, an associate professor of biomedical engineering at Tufts University.
At the same time, he believes there should be a “willingness to advance technology.”
CRISPR technology is advancing at a breakneck pace.
Researchers sought to cure six patients with a rare hereditary illness called transthyretin amyloidosis with a novel technique that distributes CRISPR straight to cells in the liver in a limited, six-person trial published in the New England Journal of Medicine last month.
Transthyretin amyloidosis is a condition in which the body accumulates a faulty protein called amyloid, causing gradual nerve damage and, in many cases, heart failure.
Symptoms might appear as early as your late twenties, and the disease usually kills you seven to twelve years after you first notice them.
Julian Gillmore, a professor of medicine at University College London’s Royal Free Hospital and the study’s principal author, adds, “It truly is a horrible condition.”
The research is the first step in a phase one clinical trial for a medication called NTLA-2001, which encapsulates CRISPR technology in a small blob known as a lipid nanoparticle.
The containers transport gene-editing technology to the liver, which produces virtually all of the faulty protein transthyretin.
The CRISPR technology corrects the faulty cells until the liver generates the proper version of transthyretin.
The study’s primary objective was to determine the medication’s safety, but because excess amyloid causes the disease’s symptoms, any reduction in symptoms noticed throughout the experimental trial suggests that the treatment is effective.
The study’s subjects were split into two groups: three received a lesser dose of CRISPR-infused lipid nanoparticles, and three received a slightly greater amount.
The number of dysfunctional liver cells dropped by almost half in those who received the lower dose, and about 90 percent in those who received the larger dose.
Researchers will continue to test even greater dosages of the medication to discover which is the safest and effective.
They’ll also keep track of all the participants for two years after they’ve had the treatment to see whether there are any long-term side effects, such as cancer or other genetic disorders that might be caused by unintended gene alterations.
With CRISPR, these side effects are especially concerning. To understand why it’s helpful to have a basic understanding of how technology works.
An experiment in the dark
The acronym CRISPR refers to “clustered regularly interspaced short palindromic repeats,” which are short, repeating genetic sequences found throughout bacteria’s genomes.
Bacteria store the genetic sequences of viruses that previously infected the organism between these regions.
Infected bacteria may “remember” parts of the invading microorganism and assault viruses containing these genes by breaking them up when they attack again.
Cas-9 is a protein that cuts up the genetic material of invading viruses (CRISPR stands for “CRISPR-associated”).
Doudna and Charpentier discovered that by changing the Cas-9 protein’s biological “guide,” they could persuade it to create a cut in DNA anyplace they chose in a genome, allowing any genes to be silenced or new ones to be introduced.
Though gene-editing existed before CRISPR, the new method was considerably easier to apply and far less expensive than previous procedures.
It does, however, have limits.
According to Martin Schiller, executive director of the Nevada Institute for Personalized Medicine and a professor of biological sciences at the University of Nevada who was not involved in the work, CRISPR technology can “tolerate non-exact sequences.”
That means it can have what’s known as off-target effects, which means it can alter sequences that are similar but not identical to the defective genes the technology is supposed to fix.
According to Schiller, this can have catastrophic repercussions. A genetic mutation, for example, might cause cancer by instructing cells to divide uncontrollably.
One of the primary benefits of the new technology is that it allows CRISPR to reach all or most liver cells, but this potential for damage complicates one of the key benefits of the new technology, which is that it allows CRISPR to reach all or most liver cells.
According to Xu, there is presently no alternative method to utilize CRISPR to treat liver disease.
Although it is feasible to edit liver cells outside the body, doctors are unable to remove a person’s liver to do so, and altering only select cells would not be useful in treating the condition.
According to Xu, there has been some study on altering liver stem cells outside the body, which would impact all liver cells, but it would be more expensive and harder to gather enough cells.
When scientists employ CRISPR outside of the body, on the other hand, they can sequence genomes to detect any rogue editing, according to Schiller.
They have no means of knowing if something went wrong when the editing takes place in the body.
The study’s researchers took steps to avoid off-target consequences.
They utilized a computer tool to detect regions at risk of being mistakenly targeted by CRISPR in pre-clinical research on human liver cells.
They discovered that all of the sections were in non-coding portions of the genome, which means that these DNA sequences do nothing as far as scientists can determine.
Even yet, scientists found no off-target effects when they investigated these regions in a sample of human liver cells in a petri dish in the lab.
This outcome comforted Gillmore, the study’s primary author. However, not everyone believes that technology will always be without drawbacks.
According to Schiller, the research was tiny, making it almost difficult to determine whether, for example, a person acquiring cancer in two years is related to the experiment or would have occurred anyway.
He admits, “It’s a shot in the dark.” “We have no idea what will happen.”
CRISPR’s Long-Term Prospects
This breakthrough comes after nearly a decade of research into novel CRISPR medicinal applications.
CRISPR was tried on a patient with sickle cell disease for the first time in 2019, and scientists injected CRISPR directly into the body for the first time last year—into the eye—to explore therapy for a rare genetic ailment that causes blindness.
When tested on mice, a CRISPR-based HIV therapy appeared to be effective, albeit it has yet to be tried in humans.
Immunotherapy therapies that use CRISPR to alter immune cells so that they can better target cancer are being explored.
Although there are always dangers with gene-editing, Gillmore and Tuft’s Xu, who was not involved in the work, regard the new method as a milestone and believe it may be used to other illnesses that affect liver cells in the future.
Intellia Therapeutics, the biotech company that led the development of NTLA-2001 and co-funded the trial with Regeneron Pharmaceuticals, has already developed an altered version of the drug for treating hereditary angioedema, a genetic disease that causes spontaneous episodes of severe swelling beneath the skin, which they hope to test on people shortly.
This medication would travel to liver cells, targeting a gene that affects overproduction of the protein bradykinin, which causes swelling, similar to transthyretin amyloidosis.
However, Schiller has doubts about the new method’s potential.
He doesn’t anticipate CRISPR being extensively utilized in the future in the same way that it was in this work since it can have potentially detrimental off-target consequences.
Instead, he believes CRISPR will be used mostly for what it has been used for: altering genes while cells are outside the body.
He also believes that another gene-editing method called TALEN, which uses less off-target editing and is more difficult and expensive to deploy, has more potential in treating illnesses.
However, all three believe that gene editing will be critical in the future of medicine.
Using the same type of lipid nanoparticle, Xu is working on developing technologies that might transport gene treatments to other organs, not just the liver, in his study.
He expects that this new development will be followed by additional organ-targeting technologies.
He also sees CRISPR as having the potential to treat other incurable human diseases with genetic components, such as Huntington’s and Alzheimer’s.
“If we can utilize CRISPR to cure such diseases, it can help a lot of people,” he says.