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Nano-Sized Solution for Efficient and Versatile CRISPR Gene Editing

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Nanocapsule for Gene Editing
Caption: Nanocapsule containing its gene-editing payload.
Credit: Guojun Chen and Amr Abdeen, University of Wisconsin-Madison

If used to make non-heritable genetic changes, CRISPR gene-editing technology holds tremendous promise for treating or curing a wide range of devastating disorders, including sickle cell disease, vision loss, and muscular dystrophy. Early efforts to deliver CRISPR-based therapies to affected tissues in a patient’s body typically have involved packing the gene-editing tools into viral vectors, which may cause unwanted immune reactions and other adverse effects.

Now, NIH-supported researchers have developed an alternative CRISPR delivery system: nanocapsules. Not only do these tiny, synthetic capsules appear to pose a lower risk of side effects, they can be precisely customized to deliver their gene-editing payloads to many different types of cells or tissues in the body, which can be extremely tough to do with a virus. Another advantage of these gene-editing nanocapsules is that they can be freeze-dried into a powder that’s easier than viral systems to transport, store, and administer at different doses.

In findings published in Nature Nanotechnology [1], researchers, led by Shaoqin Gong and Krishanu Saha, University of Wisconsin-Madison, developed the nanocapsules with specific design criteria in mind. They would need to be extremely small, about the size of a small virus, for easy entry into cells. Their surface would need to be adaptable for targeting different cell types. They also had to be highly stable in the bloodstream and yet easily degraded to release their contents once inside a cell.

After much hard work in the lab, they created their prototype. It features a thin polymer shell that’s easily decorated with peptides or other ingredients to target the nanocapsule to a predetermined cell type.

At just 25 nanometers in diameter, each nanocapsule still has room to carry cargo. That cargo includes a single CRISPR/Cas9 scissor-like enzyme for snipping DNA and a guide RNA that directs it to the right spot in the genome for editing.

In the bloodstream, the nanocapsules remain fully intact. But, once inside a cell, their polymer shells quickly disintegrate and release the gene-editing payload. How is this possible? The crosslinking molecules that hold the polymer together immediately degrade in the presence of another molecule, called glutathione, which is found at high levels inside cells.

The studies showed that human cells grown in the lab readily engulf and take the gene-editing nanocapsules into bubble-like endosomes. Their gene-editing contents are then released into the cytoplasm where they can begin making their way to a cell’s nucleus within a few hours.

Further study in lab dishes showed that nanocapsule delivery of CRISPR led to precise gene editing of up to about 80 percent of human cells with little sign of toxicity. The gene-editing nanocapsules also retained their potency even after they were freeze-dried and reconstituted.

But would the nanocapsules work in a living system? To find out, the researchers turned to mice, targeting their nanocapsules to skeletal muscle and tissue in the retina at the back of eye. Their studies showed that nanocapsules injected into muscle or the tight subretinal space led to efficient gene editing. In the eye, the nanocapsules worked especially well in editing retinal cells when they were decorated with a chemical ingredient known to bind an important retinal protein.  

Based on their initial results, the researchers anticipate that their delivery system could reach most cells and tissues for virtually any gene-editing application. In fact, they are now exploring the potential of their nanocapsules for editing genes within brain tissue.

I’m also pleased to note that Gong and Saha’s team is part of a nationwide consortium on genome editing supported by NIH’s recently launched Somatic Cell Genome Editing program. This program is dedicated to translating breakthroughs in gene editing into treatments for as many genetic diseases as possible. So, we can all look forward to many more advances like this one.

Reference:

[1] A biodegradable nanocapsule delivers a Cas9 ribonucleoprotein complex for in vivo genome editing. Chen G, Abdeen AA, Wang Y, Shahi PK, Robertson S, Xie R, Suzuki M, Pattnaik BR, Saha K, Gong S. Nat Nanotechnol. 2019 Sep 9.

Links:

Somatic Cell Genome Editing (NIH)

Saha Lab (University of Wisconsin-Madison)

Shaoqin (Sarah) Gong (University of Wisconsin-Madison)

NIH Support: National Eye Institute; National Institute of General Medical Sciences; National Institute of Neurological Disorders and Stroke; National Heart, Lung, and Blood Institute; Common Fund

10 Comments

  • Mike Hasan says:

    WoW. Superb Advancement in Bio Technology. I wish, I can see its vast use in my life time.

  • chakri says:

    hey You write proficiently about this . that’s why i like your article and comment here thanks keep updating us.

  • Frances Mecca says:

    God Bless …. we appreciate your hard
    work. Please advise of any break through
    for Age Related Macular Dystrophy.

    • G.D. says:

      My daughter was diagnosed having FSHD hen she was a teenager. She is now 35 married and has a healthy daughter. No one in our family has this form or any form of muscular dystrophy. I’m so saddened with this terrible disease my daughter has. Is there any gene editing or any medication for this specific disease.

      Please help and advise me.
      Thank you

  • Patricia Chieffo says:

    I hope that gene editing will also be used to eradicate “Lynch Syndrome” which has passed from
    generation to generation in our family. NIH and Dr. Collins, keep moving forward with your
    amazing research toward the Cure!

  • Ash says:

    This is amazing. I have been researching for any hope that it can provide my son a “hope” to better his condition. I know it is early in the discussion, however, do you see this as potential or can this be utlizied for a possible treatment for ABI,( Anoxic Brain Injury) and RP the (gentic eye disorder) in the future? If you can please comment on that when able. Thank you.

  • sravan says:

    Wow if advancement in treatment grows faster in treatment of mental illness prevention through gene therapy it will be one of the greatest achievements of human race

  • Morgan Smith says:

    I hope and pray that Huntington’s disease HD will be the next benefit of this amazing medical breakthrough

  • Renee Konkol says:

    I am hoping this could be the answer for editing the larger sized gene mutations requiring double or triple vectors.

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