03 December 2018

Scientists reported on progress in using CRISPR gene editing techniques for the reactivation of foetal haemoglobin last weekend at the American Society of Hematology (ASH) Annual Meeting in San Diego, USA.

The effects of CRISPR genome editing techniques were examined in a non-human primate model by Dr Stefan Radtke and colleagues at the Fred Hutchinson Cancer Research Center, Seattle, USA.

The team undertook CRISPR editing at the ‘13nt-HPFH’ site of the gamma globin gene promoter, recapitulating a mutation found in people with hereditary persistence of foetal haemoglobin, in order to boost the amount of foetal haemoglobin in red blood cells.

They targeted the gene editing at a subset of blood stem cells which are capable of repopulating the entire blood and immune system, previously identified by the team. Targeting these cells can reduce the amount of the reagents needed to carry out the gene modification by 90%, the team reports.

Dr Radtke and colleagues found that stem cells edited with CRISPR techniques survive well for at least one year in rhesus macaques. This ‘proof-of-principle’ study raises the possibility of using gene editing to boost foetal haemoglobin to counteract the defective haemoglobin produced in genetic blood disorders such as sickle cell anaemia or beta thalassaemia.

Presenting the work last weekend at the ASH Annual Meeting, the researchers say it "has the potential to make gene therapy faster and safer".

They say that the edited stem cells show "robust engraftment" and persistence, with "marked and stable" reactivation of foetal haemoglobin, and no obvious adverse effects.

They add that, importantly, they have validated the targeting of the smaller subset of blood stem cells, "which reduces the need for editing reagents without compromising the gene modification and engraftment efficiencies".

In conclusion, they add: "These are the first data in a clinically relevant large animal model to demonstrate the feasibility and clinical applicability of CRISPR-mediated foetal haemoglobin reactivation.

"The successful targeting and engraftment of our hematopoietic stem cell-enriched population should also have significant implications for gene therapy and editing of other genetic diseases."

Source: Fred Hutchinson Cancer Research Center- https://ash.confex.com/ash/2018/webprogram/Paper112996.html


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