Base editing HbS to HbG-Makassar improves hemoglobin function supporting its use in sickle cell disease

Area of Science:

• Hematology
• Molecular Biology
• Gene Editing

Background:

• Sickle cell disease is caused by sickle hemoglobin (HbS).
• Adenine base editing offers a potential therapeutic strategy by converting HbS to HbG (G-Makassar hemoglobin).
• The functional assessment of HbG and its impact on red blood cells (RBCs) requires further investigation.

Purpose of the Study:

• To characterize the quality and functionality of purified HbG.
• To assess the mature red blood cell (RBC) environment in a mouse model expressing HbG.
• To evaluate the efficacy of adenine base editing for sickle cell disease treatment.

Main Methods:

• Development of a mouse model for HbG characterization.
• Assessment of purified HbG polymerization under hypoxia.
• Analysis of red blood cell (RBC) dehydration, function, and sickling.
• Evaluation of blood counts, mitochondrial retention, and organ function.

Main Results:

• Purified HbG showed normal appearance and no polymerization under hypoxia.
• RBCs containing HbGS exhibited dehydration, altered function, and increased sickling under hypoxia.
• HbGS RBCs were intermediate in severity between HbAS and HbSS, while HbGG RBCs were similar to HbAA.
• Organ function in HbGS mice was comparable to HbAS mice.

Conclusions:

• While HbG shows promise, the resulting red blood cell (RBC) environment requires careful functional assessment.
• Dehydration and sickling of HbGS RBCs highlight potential challenges for gene editing strategies.
• Evaluating the mature red cell environment is crucial for developing effective gene editing therapies for hematologic disorders.