A
gene-sequence swap using CRISPR to cure hemophilia
-For the first time chromosomal
defects responsible for hemophilia have been corrected in patient-specific
iPSCs using
CRISPR-Cas9 nucleases
July
24, 2015
Sufferers
of hemophilia live in a perpetual state of stress and anxiety: their joints
wear down prematurely and they have bleeding episodes that feel like they will
never end. Their bodies lack the ability
to make the clotting factor responsible for the coagulation of blood so any cut
or bruise can turn into an emergency without immediate treatment.
Hemophilia
A occurs in about 1 in 5,000 male births and almost half
of severe cases are caused by identified “chromosomal inversions”. In a chromosomal inversion, the order of the
base pairs on the chromosome are reversed so the gene doesn’t express properly
and the sufferer lacks the blood coagulation factor VIII (F8) gene, which
causes blood to clot in healthy people.

A
Korean team led by Director of the Center for Genome Engineering Jin-Soo Kim,
Institute for Basic Science (IBS) and Professor Dong-Wook Kim at Yonsei
University has experimented with hemoplia A-derived induced pluripotent stem
cells (iPSCs) and hemoplia mice and found a way to correct this
inversion and reverse the clotting factor deficiency that causes hemophilia
A.
This
was the first time a type of stem cell called iPSCs--which possess the ability
to change into any cell type in the body--was used in a procedure like this.
The urinary cells
were collected from patients with the chromosomal inversions causing hemophilia to
make iPSCs,
the team applied CRISPR-Cas9 nucleases (Clustered Regularly Interspaced Short Palindromic
Repeats-CRISPR associated protein 9) to them.
The
CRISPR-Cas9 reverted the F8 genes which enabled them to function correctly. Corrected-iPSCs were induced to
differentiate into mature endothelial cells which expressed the F8 gene. These new endothelial cells were able to
reverse the F8 deficiency. To verify
that the process worked, the endothelial cells with the
inversion-corrected genes were transplanted into F8 deficient mice (mice with
hemophilia A) and the mice started producing the F8 clotting factor on their
own, which essentially cured them of hemophilia A.
According
to Director Jin-Soo Kim, “We used CRISPR RGENs [RNA-guided engineered
nucleases] to repair two recurrent, large chromosomal inversions responsible
for almost half of all severe hemophilia A cases.” Professor Dong-Wook Kim added, “To the
best of our knowledge, this report is the first demonstration that chromosomal
inversions or other large rearrangements can be corrected using RGENs or any
other programmable nuclease in patient iPSCs.”
What may be equally as important to the ability to
reverse the chromosomal inversion is the fact that there was no evidence of
off-target mutations resulting from the correction. This was a precision procedure: only the
parts of genome that the team wanted to change were affected.
These
findings open the door for further testing and if the results are anything like
the mice trials, the future of this treatment looks promising.
By
Daniel Kopperud
Notes for
editors
-
References
Chul-Yong Park, Duk Hyoung Kim, Jeong Sang Son, Jin Jea
Sung, Jaehun Lee, Sangsu Bae, Jong-Hoon Kim, Dong-Wook Kim, and Jin-Soo Kim
(2015), Functional Correction of Large Factor VIII Gene Chromosomal Inversions
in Hemophilia A
Patient-Derived iPSCs Using CRISPR-Cas9, Cell Stem Cell,
DOI: http://dx.doi.org/10.1016/j.stem.2015.07.001
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Media
Contact
For further information or to request media
assistance, please contact: Mr. Shi Bo Shim, Head of Department of
Communications, Institute for Basic Science (+82-42-878-8189; sibo@ibs.re.kr)
or Ms. Sunny Kim, Department of Communications, Institute for Basic Science
(+82-42-878-8135; Sunnykim@ibs.re.kr)
Professor Dong-Wook Kim at Yonsei University,
College of Medicine, Department of Physiology (+82-2-2228-1703;dwkim2@yuhs.ac)
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About
the Institute for Basic Science (IBS)
IBS was founded in 2011 by the government of the Republic of Korea with the
sole purpose of driving forward the development of basic science in Korea It
comprises a total of 50 research centers in all fields of basic science,
including mathematics, physics, chemistry, life science, earth science and
interdisciplinary science. IBS
has launched 24 research centers as of January 2015.There are eight physics,
one mathematics, six chemistry, seven life science, and two interdisciplinary
research centers.
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