CRISPR, a tool for editing the genetic code in living organisms, was first discovered in 2007. Since then, the prospect of eliminating diseases by editing the human genome has been hovering on the edge of science fiction and reality.
Here are four incredible CRISPR breakthroughs that happened this year.
Better Precision with a Tiny Protein
"When we think about how CRISPR will be applied in the future, that is really one of the most important bottlenecks to the field right now: delivery," Jennifer Doudna, who won the Nobel Prize in Chemistry along with Emmanuelle Charpentier in October for creating CRISPR, told Genetic Engineering News.
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Accessing DNA in living cells has been the biggest challenge for CRISPR. The most widely used CRISPR gene editing system uses a protein called Cas9, which is naturally found in bacteria and archaea. Their biological role is to fight off viruses by destroying the viruses' DNA and cutting it out of their genomes.
However, scientists can use them as "DNA scissors," which can be used to cut disease-causing mutations out of any DNA.
The trouble is Cas9, as well as other proteins used in different CRISPR systems, are all really bulky, which makes it difficult to access the smallest nooks and crannies of the human genome.
However, in July Doudna and her University of California Berkeley team announced that they found a new Cas protein.
Drumroll, please. Enter the tiny CasΦ (pronounced "Cas-phi").
At practically half the size, CasΦ can reach areas of the human genome that most CRISPR gene editing proteins cannot. This new protein could be a game-changer for genetic engineering.
Gene Therapy Seen as a Cure for Sickle Cell Disease
This year researchers announced the results of an on-going clinical trial that tested CRISPR's ability to edit the DNA of living cells and possibly cure genetic diseases in humans.
The study focused on two of the most common genetic disorders globally — sickle cell disease and beta-thalassemia. The only cure for these blood diseases is via a stem cell transplant from a viable donor. But often, the recipients have to take immunosuppressants for months or years, with difficult side effects.
The trials involved collecting blood stem cells from the patients. Then, researchers used CRISPR to alter the cells' genes, and finally transplanted the stem cells back into the patients. Several months later, when patients reported that their symptoms were gone, the scientific community hailed the study as a gene therapy breakthrough — calling it a cure.
"I am encouraged by the preliminary results, which demonstrate, in essence, a functional cure for patients with beta thalassemia and sickle cell disease," researcher Haydar Frangoul said in a news release.
The next step is expanding the study by enrolling 45 patients and observing them long-term.
Gene-Edited Pigs Could Be Future Organ Donors
The U.S. doesn't have enough donor organs to fulfill every need. As a result, approximately 17 people die each day because they couldn't get the liver, heart, or lung they required.
To solve this shortage, scientists have been looking into cross-species donation — or xenotransplantation — for a decade, with little progress. Our immune system is designed to attack intruders, which is excellent when you have the flu, but it makes xenotransplantation practically impossible.
"The approach, if validated through further studies, could help solve global organ shortage (and) alleviate transplantation needs."
Now, thanks to CRISPR, xenotransplantation could be possible. Using CRISPR, researchers at Qihan Biotech modified the DNA of pigs to make them more compatible with humans. The researchers made 13 genetic modifications to the pigs, all in the hopes of making them more acceptable to the human body. In vitro lab tests showed promise — cells from the gene-edited pigs appeared less likely to be rejected by the human immune system than those of unmodified animals.
Further studies are underway: the team is now testing an organ transplant from a gene-edited pig into a primate.
CRISPR Enters The Human Body for the First Time
Scientists at the Casey Eye Institute in Portland used CRISPR inside the human body for the first time — in a patient that had an inherited form of blindness.
Doctors dropped the gene-editing tool behind the retina via three drops of liquid that passed through a tube the size of a human hair. Once in the body, CRISPR went to work. It snipped the mutated gene on both sides of the problem area. They hope that once the mutation was removed, the snipped DNA will reconnect itself, allowing the gene to function as it should. They are now in clinical trials.
"Once the cell is edited, it's permanent and that cell will persist hopefully for the life of the patient," because these cells don't divide, said one study leader not involved in this first case, Dr. Eric Pierce at Massachusetts Eye and Ear.
If all goes according to plan, the patient should regain their vision within a few months. Next, the doctors plan to further test the procedure on 18 children and adults.
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