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Thu June 26, 2014

A CRISPR Way To Fix Faulty Genes

Originally published on Wed October 8, 2014 1:29 pm

Scientists from many areas of biology are flocking to a technique that allows them to work inside cells, making changes in specific genes far faster — and for far less money — than ever before.

"It's really powerful, it's a really exciting development," says Craig Mello of the University of Massachusetts Medical School. He won the Nobel Prize in 2006 for a different technique that also lets scientists modify how genes work. But, Mello says, this new genetic tool – known as CRISPR for clustered regularly interspaced short palindromic repeats — is more powerful, "because now you can essentially change a genome at will to almost anything you want. The sky's the limit."

Sure, scientists previously have made enormous strides in their ability to do things with genes: modifying them, moving them from cell to cell, even animal to animal.

But doing these things has been time consuming and expensive. It looks like CRISPR will change all that.

Mello thinks medical applications for CRISPR are not far off. He's formed a company, CRISPR Therapeutics, to develop therapies for people with genetic blood diseases like sickle cell and thalassemia. He says it's been possible, in theory, to treat these diseases by removing a patient's bone marrow, repairing the damaged gene, and then returning the repaired cells to the patient. In practice, Mello says, succeeding with that approach has been nearly impossible.

"But now, the cost for that has come down to where it's really feasible to tailor therapies using the patient's own cells," he says, "essentially correcting their genetic disease." Though a lot of testing still needs to be done before doctors can say the CRISPR technique is safe and effective enough for use in treating patients, even many scientists not directly involved in the research are enthusiastic about its possibilities.

CRISPR is one of those interesting inventions that comes, not from scientists explicitly trying to cure a disease, but from researchers trying to understand something fundamental about nature.

Jennifer Doudna's research at the University of California, Berkeley has focused on how bacteria fight the flu. It turns out bacteria don't like getting flu any more than the rest of us do. Doudna says the way bacteria fight off a flu virus gave her and her colleagues an idea.

Bacteria have special enzymes that can cut open the DNA of an invading virus and make a change in the DNA at the site of the cut — essentially killing the virus.

Doudna and other scientists figured out how this defense system works in bacteria; that was interesting all by itself. But then they realized that they could modify these enzymes to recognize any DNA sequence, not just the DNA sequence of viruses that infect bacteria.

"So this is now enabling researchers to introduce changes into the genetic code of cells and organisms at essentially any site," she says.

Doudna realized from the start that she was on to something big. "I remember really feeling ... the hairs on the back of my neck," she recalls. "Because I thought, wow, if this could work in animal or plant cells, this could be a very, very useful and very powerful tool. Honestly, I didn't even realize at the time how powerful."

Like Craig Mello, Doudna also foresees medical applications for CRISPR, and she is a co-founder of a biotech company that hopes to use the technology to develop new therapies.

Copyright 2014 NPR. To see more, visit http://www.npr.org/.

Transcript

MELISSA BLOCK, HOST:

Biologists are pretty excited about a new technique they've started using. It goes by the acronym, CRISPR. That's C-R-I-S-P-R. It allows them to manipulate genes and cells in a way they've never been able to do in the past. As part of his series, "Joe's Big Idea," NPR's Joe Palca has been exploring inventions that can change the world. Today he tells us why scientists think CRISPR could launch a new era in biology and medicine. And yes, he'll tell us what CRISPR stands for eventually.

JOE PALCA, BYLINE: Sure, scientists have made enormous strides in their ability to do things with genes - modifying them, moving them from cell to cell, even animal to animal. But doing these things is time-consuming and expensive. It looks like CRISPR will change all that.

CRAIG MELLO: It's really powerful. It's a really exciting development.

PALCA: That's Craig Mello of the University of Massachusetts medical school. He won the Nobel Prize for a technique that also lets you modify how genes work, but he says CRISPR is more powerful.

MELLO: Because now you can essentially change a genome at will to almost anything you want, the sky's the limit.

PALCA: Not only is CRISPR less expensive to use, but making precise genetic changes in cells now takes hours instead of days or weeks. Mello thinks medical applications for CRISPR are not far off. He's formed a company to develop therapies for people with genetic blood diseases like sickle-cell and thalassemia. He says it's been possible, in theory, to treat these diseases by removing a patient's bone marrow, repairing the damaged gene, and then transplanting the repaired cells back to the patient. Mello says in practice it's been nearly impossible to accomplish this.

MELLO: But now, the cost for that has come down to where it's really feasible to tailor-make therapies using the patient's own cells and essentially correcting their genetic disease.

PALCA: CRISPR is one of those interesting inventions that didn't come from scientists who were explicitly trying to cure a disease, but who wanted to understand something fundamental about nature.

JENNIFER DOUDNA: How to bacteria fight the flu?

PALCA: Jennifer Doudna is at the University of California, Berkeley. Turns out bacteria don't like getting flu any more than the rest of us. Doudna says the way bacteria fight off a flu virus gave her and her colleagues an idea. Bacteria have special enzymes that can cut open the DNA of an invading virus and make a change in the DNA at the site of the cut, essentially killing the virus. Doudna and her colleagues figured out how this defense system works in bacteria - something that was interesting all by itself. But then they realized that they could modify these enzymes to recognize any DNA sequence, not just the DNA sequence of viruses that infect bacteria.

DOUDNA: So this is now enabling researchers to introduce changes into the genetic code of cells and organisms at essentially any site that they might wish to do so.

PALCA: Doudna realized from the start that she was onto something big.

DOUDNA: I remember really feeling sort of the hairs on the back of my neck, you know, because I thought, wow, you know, if this could work in animal or plant cells, this could be a very, very useful and very powerful tool. Honestly I didn't even realize at the time how powerful. I was really thinking, boy, if it works even at all it will be very interesting.

DOUDNA: Doudna is also involved in a biotech company that hopes to exploit CRISPR for medical technologies. Scientists have just started exploring what they can do with CRISPR. The first applications may be in the field of medicine, but when scientists get their hands on any new tool it's usually best to expect the unexpected. Stay tuned. Oh, and by the way if you're interested in what CRISPR is an acronym for, don't ask Craig Mello.

MELLO: It stands for clustered regularly interspersed - wait a second (Laughing). Clustered regularly interspersed...

PALCA: He got it eventually. It stands for clustered regularly interspersed short palindromic repeats. So now you know. Joe Palca, NPR News.

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