Generation of Rh D‐negative blood using CRISPR/Cas9.

Blood supply shortages, especially the shortage of rare blood types, threaten the current medical system. Research on stem cells has shed light on in vitro blood cell manufacturing. The in vitro production of universal red blood cells (RBCs) from induced pluripotent stem cells (iPSCs) has become the focus of transfusion medicine. To obtain O‐type Rh D‐negative blood, we developed O‐type Rh D‐negative human (h)iPSCs using homology‐directed repair (HDR)‐based CRISPR/Cas9. HuAiPSCs derived from human umbilical arterial endothelial cells and showing haematopoietic differentiation preferences were selected for gene modification. Guide RNAs (gRNAs) were selected, and a donor template flanked by gRNA‐directed homologous arms was set to introduce a premature stop code to RHD exon 2. CRISPR/Cas9 gene editing has resulted in the successful generation of an RHD knockout cell line. The HuAiPSC‐A1‐RHD−/− cell line was differentiated into haematopoietic stem/progenitor cells and subsequently into erythrocytes in the oxygen concentration‐optimized differentiation scheme. HuAiPSC‐A1‐RHD−/− derived erythrocytes remained positive for the RBC markers CD71 and CD235a. These erythrocytes did not express D antigen and did not agglutinate in the presence of anti‐Rh D reagents. In conclusion, taking the priority of haematopoietic preference hiPSCs, the HDR‐based CRISPR/Cas9 system and optimizing the erythroid‐lineage differentiation protocol, we first generated O‐type Rh D‐negative universal erythrocytes from RHD knockout HuAiPSCs. Its production is highly efficient and shows great potential for clinical applications. [ABSTRACT FROM AUTHOR]