Using CRISPR-Cas9–mediated gene editing, researchers based at the U.K.-based NIHR Blood and Transplant Research Unit (NIHR BTRU) in red cell products, BrisSynBio Center, and NHS Blood and Transplant in Bristol created individual cell lines in which specific blood group genes were altered to prevent the expression of blood group proteins that can cause immune reactions. 

Building on this gene-editing approach, the team then went on to produce cells that combined the deletion of multiple blood groups in a single cell line that could be differentiated to generate functional novel red blood cells with broad transfusion compatibility. Transfusions of red blood cells edited to improve compatibility could provide better treatments for those patients whose clinical needs are difficult to meet. 

The study (“Enhancement of Red Blood Cell Transfusion Compatibility Using CRISPR-Mediated Erythroblast Gene Editing”), published in EMBO Molecular Medicine, provides the first proof-of-principle demonstration that gene editing can be used in combination with laboratory culture of red blood cells to generate rare or customized red blood cells for patients with specific needs, according to the scientists. 

“Regular blood transfusion is the cornerstone of care for patients with red blood cell (RBC) disorders such as thalassaemia or sickle-cell disease. With repeated transfusion, alloimmunisation often occurs due to incompatibility at the level of minor blood group antigens. We use CRISPR-mediated genome editing of an immortalised human erythroblast cell line (BEL-A) to generate multiple enucleation competent cell lines deficient in individual blood groups. Edits are combined to generate a single cell line deficient in multiple antigens responsible for the most common transfusion incompatibilities: ABO (Bombay phenotype), Rh (Rhnull), Kell (K0), Duffy (Duffynull), GPB (SsU). These cells can be differentiated to generate deformable reticulocytes, illustrating the capacity for coexistence of multiple rare blood group antigen null phenotypes,” write the investigators.

“This study provides the first proof-of-principle demonstration of combinatorial CRISPR-mediated blood group gene editing to generate customisable or multi-compatible RBCs for diagnostic reagents or recipients with complicated matching requirements.”

While the authors stress the many challenging technical obstacles that must be overcome before this approach could be translated to a clinical product, they believe their work does provide a window into the possible applications of red blood cells produced from gene-edited cell lines.

“Blood made using genetically edited cells could one day provide compatible transfusions for a group of patients for whom blood matching is difficult or impossible to achieve within the donor population. However, much more work will still be needed to produce blood cells suitable for patient use,” says Ashley Toye, Ph.D., director of the Bristol NIHR BTRU.

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