Have you heard? A revolution has seized the scientific community. Within only a few years, research labs worldwide have adopted a new technology that facilitates making specific changes in the DNA of humans, other animals, and plants. Compared to previous techniques for modifying DNA, this new approach is much faster and easier. This technology is referred to as “CRISPR,” and it has changed not only the way basic research is conducted, but also the way we can now think about treating diseases [1,2].
What is CRISPR
CRISPR is an acronym for Clustered Regularly Interspaced Short Palindromic Repeat. This name refers to the unique organization of short, partially palindromic repeated DNA sequences found in the genomes of bacteria and other microorganisms. While seemingly innocuous, CRISPR sequences are a crucial component of the immune systems [3] of these simple life forms. The immune system is responsible for protecting an organism’s health and well-being. Just like us, bacterial cells can be invaded by viruses, which are small, infectious agents. If a viral infection threatens a bacterial cell, the CRISPR immune system can thwart the attack by destroying the genome of the invading virus [4]. The genome of the virus includes genetic material that is necessary for the virus to continue replicating. Thus, by destroying the viral genome, the CRISPR immune system protects bacteria from ongoing viral infection.
How does it work?
Figure 1 ~ The steps of CRISPR-mediated immunity. CRISPRs are regions in the bacterial genome that help defend against invading viruses. These regions are composed of short DNA repeats (black diamonds) and spacers (colored boxes). When a previously unseen virus infects a bacterium, a new spacer derived from the virus is incorporated amongst existing spacers. The CRISPR sequence is transcribed and processed to generate short CRISPR RNA molecules. The CRISPR RNA associates with and guides bacterial molecular machinery to a matching target sequence in the invading virus. The molecular machinery cuts up and destroys the invading viral genome. Figure adapted from Molecular Cell 54, April 24, 2014 [5].
Interspersed between the short DNA repeats of bacterial CRISPRs are similarly short variable sequences called spacers (FIGURE 1). These spacers are derived from DNA of viruses that have previously attacked the host bacterium [3]. Hence, spacers serve as a ‘genetic memory’ of previous infections. If another infection by the same virus should occur, the CRISPR defense system will cut up any viral DNA sequence matching the spacer sequence and thus protect the bacterium from viral attack. If a previously unseen virus attacks, a new spacer is made and added to the chain of spacers and repeats.
The CRISPR immune system works to protect bacteria from repeated viral attack via three basic steps [5]:
Step 1) Adaptation – DNA from an invading virus is processed into short segments that are inserted into the CRISPR sequence as new spacers.
Step 2) Production of CRISPR RNA – CRISPR repeats and spacers in the bacterial DNA undergo transcription, the process of copying DNA into RNA (ribonucleic acid). Unlike the double-chain helix structure of DNA, the resulting RNA is a single-chain molecule. This RNA chain is cut into short pieces called CRISPR RNAs.
Step 3) Targeting – CRISPR RNAs guide bacterial molecular machinery to destroy the viral material. Because CRISPR RNA sequences are copied from the viral DNA sequences acquired during adaptation, they are exact matches to the viral genome and thus serve as excellent guides.
The specificity of CRISPR-based immunity in recognizing and destroying invading viruses is not just useful for bacteria. Creative applications of this primitive yet elegant defense system have emerged in disciplines as diverse as industry, basic research, and medicine.
What are some applications of the CRISPR system?
In Industry
The inherent functions of the CRISPR system are advantageous for industrial processes that utilize bacterial cultures. CRISPR-based immunity can be employed to make these cultures more resistant to viral attack, which would otherwise impede productivity. In fact, the original discovery of CRISPR immunity came from researchers at Danisco, a company in the food production industry [2,3]. Danisco scientists were studying a bacterium called Streptococcus thermophilus, which is used to make yogurts and cheeses. Certain viruses can infect this bacterium and damage the quality or quantity of the food. It was discovered that CRISPR sequences equipped S. thermophilus with immunity against such viral attack. Expanding beyond S. thermophilus to other useful bacteria, manufacturers can apply the same principles to improve culture sustainability and lifespan.
In the Lab
Beyond applications encompassing bacterial immune defenses, scientists have learned how to harness CRISPR technology in the lab [6] to make precise changes in the genes of organisms as diverse as fruit flies, fish, mice, plants and even human cells. Genes are defined by their specific sequences, which provide instructions on how to build and maintain an organism’s cells. A change in the sequence of even one gene can significantly affect the biology of the cell and in turn may affect the health of an organism. CRISPR techniques allow scientists to modify specific genes while sparing all others, thus clarifying the association between a given gene and its consequence to the organism.
Rather than relying on bacteria to generate CRISPR RNAs, scientists first design and synthesize short RNA molecules that match a specific DNA sequence—for example, in a human cell. Then, like in the targeting step of the bacterial system, this ‘guide RNA’ shuttles molecular machinery to the intended DNA target. Once localized to the DNA region of interest, the molecular machinery can silence a gene or even change the sequence of a gene (Figure 2)! This type of gene editing can be likened to editing a sentence with a word processor to delete words or correct spelling mistakes. One important application of such technology is to facilitate making animal models with precise genetic changes to study the progress and treatment of human diseases.
Figure 2 ~ Gene silencing and editing with CRISPR. Guide RNA designed to match the DNA region of interest directs molecular machinery to cut both strands of the targeted DNA. During gene silencing, the cell attempts to repair the broken DNA, but often does so with errors that disrupt the gene—effectively silencing it. For gene editing, a repair template with a specified change in sequence is added to the cell and incorporated into the DNA during the repair process. The targeted DNA is now altered to carry this new sequence.
In Medicine
With early successes in the lab, many are looking toward medical applications of CRISPR technology. One application is for the treatment of genetic diseases. The first evidence that CRISPR can be used to correct a mutant gene and reverse disease symptoms in a living animal was published earlier this year [7]. By replacing the mutant form of a gene with its correct sequence in adult mice, researchers demonstrated a cure for a rare liver disorder that could be achieved with a single treatment. In addition to treating heritable diseases, CRISPR can be used in the realm of infectious diseases, possibly providing a way to make more specific antibiotics that target only disease-causing bacterial strains while sparing beneficial bacteria [8]. A recent SITN Waves article discusses how this technique was also used to make white blood cells resistant to HIV infection [9].
The Future of CRISPR
Of course, any new technology takes some time to understand and perfect. It will be important to verify that a particular guide RNA is specific for its target gene, so that the CRISPR system does not mistakenly attack other genes. It will also be important to find a way to deliver CRISPR therapies into the body before they can become widely used in medicine. Although a lot remains to be discovered, there is no doubt that CRISPR has become a valuable tool in research. In fact, there is enough excitement in the field to warrant the launch of several Biotech start-ups that hope to use CRISPR-inspired technology to treat human diseases [8].
Ekaterina Pak is a Ph.D. student in the Biological and Biomedical Sciences program at Harvard Medical School.
References:
1. Palca, J. A CRISPR way to fix faulty genes. (26 June 2014) NPR < http://www.npr.org/blogs/health/2014/06/26/325213397/a-crispr-way-to-fix-faulty-genes> [29 June 2014]
2. Pennisi, E. The CRISPR Craze. (2013) Science, 341 (6148): 833-836.
3. Barrangou, R., Fremaux, C., Deveau, H., Richards, M., Boyaval, P., Moineau, S., Romero, D.A., and Horvath, P. (2007). CRISPR provides acquired resistance against viruses in prokaryotes. Science 315, 1709–1712.
4. Brouns, S.J., Jore, M.M., Lundgren, M., Westra, E.R., Slijkhuis, R.J., Snijders, A.P., Dickman, M.J., Makarova, K.S., Koonin, E.V., and van der Oost, J. (2008). Small CRISPR RNAs guide antiviral defense in prokaryotes. Science 321, 960–964.
5. Barrangou, R. and Marraffini, L. CRISPR-Cas Systems: Prokaryotes Upgrade to Adaptive Immunity (2014). Molecular Cell 54, 234-244.
6. Jinkek, M. et al. A programmable dual-RNA-guided DNA endonuclease in adaptive bacterial immunity. (2012) 337(6096):816-21.
7. CRISPR reverses disease symptoms in living animals for first time. (31 March 2014). Genetic Engineering and Biotechnology News. <http://www.genengnews.com/gen-news-highlights/crispr-reverses-disease-symptoms-in-living-animals-for-first-time/81249682/> [27 July 2014]
8. Pollack, A. A powerful new way to edit DNA. (3 March 2014). NYTimes < http://www.nytimes.com/2014/03/04/health/a-powerful-new-way-to-edit-dna.html?_r=0> [16 July 2014]
9. Gene editing technique allows for HIV resistance? <http://sitn.hms.harvard.edu/flash/waves/2014/gene-editing-technique-allows-for-hiv-resistance/> [13 June 2014]
Who wrote this article because i need to do an in text citation on this.
Ekaterina Pak
What is meant by ‘molecular machinery’?
Molecular machinery refers to the proteins in the cell that cut the DNA–“molecular” because proteins are molecules and “machinery” because the proteins are working together to perform a job (i.e. cutting).
I would like to make a comment relating to use of CRISPER that is bound to be controversial and unlikely occur except possibly in the distant future. It has been shown that Individuals with larger medulla are more caring, more empathetic and less warlike. Use of CRISPER could could be used to induce a positive change. I do not propose this, but it is something to think about.
That’s how we got here supposedly and makes up what we are today IMO about 450,000 years ago, originating from apes according to … https://en.wikipedia.org/wiki/Zecharia_Sitchin We’re about to step into their world, I mean, how can we be so arrogant to think we’re the only intelligent form of life in the universe? and they’re getting nervous … some say they’re here!
Joseph
Already Mr. Pepelko, you consider using CRISPR to alter personality vis-a-vis actual brain alterations.
What a crazy world we live in where people are so arrogant that they feel genetic engineering is the right tool for controling behaviour. And who would they control ? The masses of course ! And who would be the controllers? The rich and corrupt of course. Be careful what you wish for. Oh too late it’s 2021 we’re all being crispr’d by our corrupt governments.
Looks like China is allowing the use of Crispr in human embryos now…
Next month, Chinese researchers will edit adult human DNA using the revolutionary CRISPR/Cas-9 tool, commonly known as CRISPR, for the first time anywhere in the world.
The researchers will attempt to cut faulty DNA out of the cells of lung cancer patients who have failed to respond to all other conventional treatments.
Chinese scientists have previously used CRISPR on non-viable human embryos, without much luck, but this is the first time any researchers, anywhere in the world, will use the tool to edit DNA in an adult.
http://www.sciencealert.com/china-s-about-to-alter-human-dna-using-a-revolutionary-tool-for-the-first-time
Can this be used to treat marfans disease? my son and my grandson have this. thank you.
We hope that one day CRISPR will be used to treat human diseases such as Marfan’s syndrome, but it is not yet used for this purpose. Scientists and doctors first need to develop safe ways to get CRISPR into humans in order to be able to use it for treatment. You can read more about CRISPR for clinical use here: http://www.sciencealert.com/crispr-gene-editing-tool-used-to-treat-genetic-disease-in-an-animal-for-the-first-time
Hi Don, unfortunately at the moment we are quite far off using crispr to cure specific diseases. Its definitely a promising field but its still not perfect, its still not 100% efficient in the lab, we aren’t sure of the potential side affects in human use, and cant introduce the machinery into some human cells yet. Wish you, your son and grandson all the best.
So sorry to hear it Don, I hope they are doing well!
How many years before this filters down to ordinary people. How much will it cost? How long will it take before the price comes down to be affordable to regular people? Sounds like a technology that will take decades to perfect.
It is said that crispr is a lot more efficient, effective, and cheaper than the alternative. Therefore, giving everyone a realistic opportunity to check it out. There after, the estimated time for a market was said to be around 8-9 years.
I have a nephew that is terminal with Hep C & curious of the liver. His amonia level which should be at 50 is at 100. 90 is considered lethal. Please advise me when this may be FDA approved & available to public. Or if you are using human test cases, he could be a candidate as he is terminal in his current state.
Keep me posted- “Interesting
Crispi can help in most diseases or it will only be in the genetic
Out Loud – a podcast that I subscribe to…
Hidden inside some of the world’s smallest organisms is one of the most powerful tools scientists have ever stumbled across. It’s a defense system that has existed in bacteria for millions of years and it may some day let us change the course of human evolution. Out drinking with a few biologists, Jad finds out about something called CRISPR. No, it’s not a robot or the latest dating app, it’s a method for genetic manipulation that is rewriting the way we change DNA. Scientists say they’ll someday be able to use CRISPR to fight cancer and maybe even bring animals back from the dead. Or, pretty much do whatever you want. Jad and Robert delve into how CRISPR does what it does, and consider whether we should be worried about a future full of flying pigs, or the simple fact that scientists have now used CRISPR to tweak the genes of human embryos.
http://www.stitcher.com/s?eid=39430706&refid=asa
can we use crisper for gene editing in Multi drug resistent tuberculosis. to treatthe mutations and again use the drugs. for example- using crisper on rifampcin resistent gene rpoB of MTB and again using the drug rifampcin to treat the MTB.
Yes we can and also we are planning to use bananas as a factor because of its radioactive genes
Can synthetic protein like those in the mRNA vaccine’s for instance then be possible introduced to our dna via a crispr like effect via bacteria or viruses found naturally in the body
will this technology cure cancer? When will the technology be available for the general public? What disease will the technology cure?
That is a very lazy question for a complicated generation changer
Alright Bob, no need for the harsh reply, Simone was only curious.
Very exciting discovery more in future
I find a question of curing cancer NOT to be “lazy” as you put it. I find YOUR comment rude in fact. Since when does a cure for cancer warrant such a rude response?
This is already there for GPs but it is too expensive for GPs for now! And yes it could be a potentially cure for cancer!
The CRISPR technology appears to be another, widening intrusion into what we are made of, and how this wonderful living organism can be altered from within, rather than through the introduction of drug therapies, and other external stimuli. The “Beauty” and the “Beast” aspects of this discovery will certainly become useful in more malevolent scientific activities than one can imagine, unless there are traceable markers that, like breadcrumbs in the forest, would allow illegal and unethical use og the technology to be tracked. I can see CRISPR as a game-changer. Are we really ready to play with it responsibly?
whenever a poster leaves a comment like this, they are really just playing out a cultural-social role of “ethical inquirer” to promote their own sense of well-being. The pertinent info here is there is a potential cure for serious human health issues. So yes, we are ready to play with it responsibly. And no, it will not certainly be used malevolently. If you choose to reply, I hope you provide documentation for your source about the certainty of malevolent science. Your post was poor.
It is naive to assume it can’t and won’t be used malevolently. The military is the main financier of this research so it would appear to me that biological warfare is the reason for its inception. It also would appear that potential cures are just a side effect of its main purpose.
So because a discovery that can benefit poeple can also be used to harm, it should never be used?
I realize you’re trying to remain positive. However, a better question would be have you ever seen a technology that hasn’t at least been attempted to be used as a weapon?
Putting that aside, recently we found our 1 year space station astronaut had a DNA change occur while in space. Given that, this technology could prove indispensable for prolonged space flight.
Obviously you haven’t heard of dual-use research and technology. Maybe you should try reading Military Medical Ethics for the 21st Century. Your post is naive and condescending.
And your post is short sighted. Not a personal attack ; just a particular view seen from a distance.
Dion `The Correlator` Smith
If you can accurately target genes and identify what the do and in human dna a then from what ive read then they should be able to remove and gene in DNA structure that cases cancer HIV and pretty much any inheratible disease for sure from the genome
The proof is HISTORY ! HISTORY ! HISTORY !
Why are breeder reactors the most ineffecient and most dangerous to deploy “only model used as reactor’s” when the first alternate developed by the same scientist at the same time , with vision to safely transform energy supply , was much safer , more effecient , and less long term volatile waste – “molten salt reactor” ? Soundly rejected ? By what reason and what reason alone ?
It could not breed weapons proliferation , to attain power and destructive capability over enemies !
The answer is , greed for power , for weapons , for control !
Do I need to review biological warfare , Gengis Kahn launching plague covered bodies in to cities , to deciimate massive numbers spreading globally in wave after wave ,, wiping out millions
Yes , the answer is
EVIL –
– Stalin, Mao , Htler, and ad infinitum, awaiting in line to be more EVIL , in more ways for more reasons ..
If it is developed and insertable into humans it will be used as a weapon by some , and those who wish not to will be forced to countermeasures by using it malevolently, in defense of there survival ..
Too late ! It is already being concieved of , then it is already secretly being tied experimentally to explore every possible dark side , if not just to be pre -pared , we should expect no less vigilance of the agencies we employ to safe guard us , to not be behind the curve.
Pandora box !
Well, we now have the jab…..
Given that people are being FORCED to undergo a treatment plan under the guise of a vaccine I think that poster was on the money. People should never be forced to be shot up with experimental drugs.
Well. Here we are in late 2021 and the whole population of the world is being forced or coerced by fear or loss of jobs or holidays or by being locked up into taking multiple experimental mRNA vaccines. I think the molevolent intent is plain to see. I believe this ilegal assault on mankind will devastate our health. You so called scientists are devoid of vision
Think of it this way: A University student develops Grave’s Disease and Type 1 Diabetes – odd at the age of 22. The Enendocrinologist says you probably had a Virus which damaged (changed) the weakened (Genetically Predisposed) section of your Chromosomes. Now some 38 years later we might develop the Medical Technology to use Crispr to cut out the bad sections replacing them with healthy matching sections from her brother. It may never work. But we can ponder such a senerio for now.
They need only look at history to know, recognize, perceive and understand that malevolence exists in this world. Turning a blind eye to this is irresponsible and ‘poor’.
What are the advancements of repairing lungs with the disease Stage 3 COPD?
My lungs were damaged in a car fire 23 years ago. I am 43 now. Is it possible to run through the park with my children before my days are up?
Beautiful.
I’m so astonished at how amazing this discovery is. You have done it again Harvard: you have made the impossible possible. I salute you. Skurr.
could it be the holy grail? we are already onto cloning so these advancements should be no surprise.