For the first time, chromosomal defects responsible for hemophilia
have been corrected in patient-specific iPSCs using CRISPR-Cas9
nucleases. Asian Scientist Newsroom | August 4, 2015 | In the Lab
AsianScientist (Aug. 4, 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 Kim Jin-Soo, Institute for Basic Science (IBS) and Professor Kim Dong-Wook at Yonsei University has experimented with hemophilia A-derived induced pluripotent stem cells (iPSCs) and hemophiliac mice and found a way to correct this inversion and reverse the clotting factor deficiency that causes hemophilia A.
This was the first time that iPSCs—which possess the ability to change into any cell type in the body—have been used in such a procedure. The researchers first collected urinary cells from patients with chromosomal inversions causing haemophilia, transforming them into iPSC cells. Then, they used CRISPR-Cas9 nucleases (Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR associated protein 9) to flip the F8 gene around, allowing it to be read correctly.
The corrected-iPSCs were then induced to differentiate into mature endothelial cells which expressed the F8 gene in the correct orientation. 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.
“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,” Kim Jin-Soo said.
“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,” Kim Dong-Wook added.
Importantly, the studied showed no evidence of off-target mutations resulting from the procedure, suggesting that it was only the desired parts of genome were changed.
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.
The article can be found at: Park et al. (2015) Functional Correction of Large Factor VIII Gene Chromosomal Inversions in Hemophilia A Patient-Derived iPSCs Using CRISPR-Cas9
Source: Institute for Basic Science; Photo: Shutterstock. Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
https://www.facebook.com/Hemophilia-Awareness-446712415406740/timeline/?ref=bookmarks
AsianScientist (Aug. 4, 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 Kim Jin-Soo, Institute for Basic Science (IBS) and Professor Kim Dong-Wook at Yonsei University has experimented with hemophilia A-derived induced pluripotent stem cells (iPSCs) and hemophiliac mice and found a way to correct this inversion and reverse the clotting factor deficiency that causes hemophilia A.
This was the first time that iPSCs—which possess the ability to change into any cell type in the body—have been used in such a procedure. The researchers first collected urinary cells from patients with chromosomal inversions causing haemophilia, transforming them into iPSC cells. Then, they used CRISPR-Cas9 nucleases (Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR associated protein 9) to flip the F8 gene around, allowing it to be read correctly.
The corrected-iPSCs were then induced to differentiate into mature endothelial cells which expressed the F8 gene in the correct orientation. 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.
“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,” Kim Jin-Soo said.
“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,” Kim Dong-Wook added.
Importantly, the studied showed no evidence of off-target mutations resulting from the procedure, suggesting that it was only the desired parts of genome were changed.
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.
The article can be found at: Park et al. (2015) Functional Correction of Large Factor VIII Gene Chromosomal Inversions in Hemophilia A Patient-Derived iPSCs Using CRISPR-Cas9
Source: Institute for Basic Science; Photo: Shutterstock. Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
https://www.facebook.com/Hemophilia-Awareness-446712415406740/timeline/?ref=bookmarks
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