New CRISPR/Cas9 technique corrects cystic fibrosis in cultured human
stem cells

Date:
August 9, 2021
Source:
Hubrecht Institute
Summary:
Researchers corrected mutations that cause cystic fibrosis in
cultured human stem cells. They used a technique called prime
editing to replace the 'faulty' piece of DNA with a healthy
piece. The study shows that prime editing is safer than the
conventional CRISPR/Cas9 technique.



FULL STORY ========================================================================== Researchers from the group of Hans Clevers (Hubrecht Institute) corrected mutations that cause cystic fibrosis in cultured human stem cells. In collaboration with the UMC Utrecht and Oncode Institute, they used a
technique called prime editing to replace the 'faulty' piece of DNA with
a healthy piece.

The study, published in Life Science Alliance on August 9th, shows that
prime editing is safer than the conventional CRISPR/Cas9 technique. "We
have for the first time demonstrated that this technique really works
and can be safely applied in human stem cells to correct cystic fibrosis."

========================================================================== Cystic fibrosis (CF) is one of the most prevalent genetic diseases
worldwide and has grave consequences for the patient. The mucus in the
lungs, throat and intestines is sticky and thick, which causes blockages
in organs. Although treatments are available to dilute the mucus and
prevent inflammations, CF is not yet curable. However, a new study from
the group of Hans Clevers (Hubrecht Institute) in collaboration with
the UMC Utrecht and Oncode Institute offers new hope.

Correcting CF mutations The researchers succeeded in correcting the
mutations that cause CF in human intestinal organoids. These organoids,
also called mini-organs, are tiny 3D structures that mimic the intestinal function of patients with CF. They were previously developed by the
same research group from stem cells of patients with CF and stored in a
biobank in Utrecht. For the study, published in Life Science Alliance,
a technique named prime editing was used to replace the piece of mutated
DNA that causes CF with a healthy piece of DNA in these organoids.

Safer than CRISPR/Cas9 Prime editing is a newer version of the
better-known gene editing technique CRISPR/Cas9. CRISPR/Cas9 cuts the DNA before correcting it. Although this corrects the mutated piece of DNA,
it also causes damage in other regions in the genome. "In our study,
prime editing proves to be a safer technique than the conventional
CRISPR/Cas9. It can build in a new piece of DNA without causing damage elsewhere in the DNA. That makes the technique promising for application
in patients," says Maarten Geurts, first author on the publication.

Swelling The mutations that cause CF are localized in the CFTR channel,
which is present in the cells of various organs including the lungs. Due
to the mutations, the channel does not function properly, leaving the
layer of mucus that covers the cells with too little water: the mucus
becomes sticky. The addition of a substance called forskolin causes
healthy organoids to swell, but this does not happen in organoids with mutations in the CFTR channel. "We applied prime editing to the mutations, after which the treated organoids demonstrated the same response as the
healthy organoids: they became swollen. That provided us with proof that
our technique worked and replaced the mutated DNA," Geurts explains.

Curing genetic diseases Now that the researchers showed that the mutations
that cause CF can be safely corrected, applications in the clinic come
one step closer. "New variants of CRISPR/Cas9, such as prime editing,
can safely correct mutations without causing damage in other regions of
the DNA. This will hopefully enable us to cure or even prevent genetic
diseases in the future." But before that, some challenges still lie ahead
for the researchers. The technique for example still needs to be adapted
for safe use in humans. "But this is a great step towards successfully
applying prime editing in the clinic," Geurts concludes.

Hans Clevers is group leader at the Hubrecht Institute for Developmental Biology and Stem Cell Research and at the Princess Ma'xima Center for
Pediatric Oncology. He is also University Professor at the Utrecht
University and Oncode Investigator.

========================================================================== Story Source: Materials provided by Hubrecht_Institute. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Maarten H Geurts, Eyleen de Poel, Cayetano Pleguezuelos-Manzano,
Rurika
Oka, Le'o Carrillo, Amanda Andersson-Rolf, Matteo Boretto,
Jesse E Brunsveld, Ruben van Boxtel, Jeffrey M Beekman, Hans
Clevers. Evaluating CRISPR-based prime editing for cancer modeling
and CFTR repair in organoids. Life Science Alliance, 2021; 4 (10):
e202000940 DOI: 10.26508/ lsa.202000940 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210809105908.htm

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