Sustained fetal hemoglobin induction in vivo is achieved by BCL11A interference and co-expressed truncated erythropoietin receptor

April 28, 2021

Associate Professor Naoya Uchida of The Institute of Medical Science, The University of Tokyo in Japan and co-researchers at National Heart Lung and Blood Institutes (NHLBI) / National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH) and St. Jude Children's Research Hospital(SJCRH) in the U.S. demonstrate that co-expression of truncated human erythropoietin receptors (thEpoR) enhances erythropoiesis of gene-modified cells, resulting in improvement of the phenotypic effect of a therapeutic vector in erythroid cells in xenograft mouse and autologous non-human primate transplantation models. It was published in "Science Translational Medicine" on April 28, 2021.

 

Abstract

Hematopoietic stem cell gene therapy for hemoglobin disorders, including sickle cell disease, requires high-efficiency lentiviral gene transfer and robust therapeutic globin expression in erythroid cells. Erythropoietin is a key cytokine for erythroid proliferation and differentiation (erythropoiesis), and truncated human erythropoietin receptors (thEpoR) have been reported in familial polycythemia. We reasoned that co-expression of thEpoR could enhance the phenotypic effect of a therapeutic vector in erythroid cells in xenograft mouse and autologous non-human primate transplantation models. We generated thEpoR by deleting 40 amino acids from the C-terminus, allowing for erythropoietin-dependent enhanced erythropoiesis of gene-modified cells. We then designed lentiviral vectors encoding both thEpoR and B-cell lymphoma/leukemia 11A (BCL11A)-targeting microRNA-adapted short hairpin RNA (shmiR BCL11A) driven by an erythroid-specific promoter. thEpoR expression enhanced erythropoiesis among gene-modified cells in vitro. We then transplanted lentiviral vector gene-modified CD34+ cells with erythroid-specific expression of both thEpoR and shmiR BCL11A and compared these to cells modified with shmiR BCL11A alone. We found that thEpoR enhanced shmiR BCL11A-based fetal hemoglobin (HbF) induction in both xenograft mice and rhesus macaques, whereas HbF induction with shmiR BCL11A alone, though robust, was transient. thEpoR/shmiR BCL11A co-expression allowed for sustained HbF induction at 20-25% in rhesus macaques for 1 year. In summary, we developed erythroid-specific thEpoR/shmiR BCL11A-expressing vectors, enhancing HbF induction in xenograft mice and rhesus macaques. The sustained HbF induction achieved by addition of both thEpoR and shmiR BCL11A may represent a viable gene therapy strategy for hemoglobin disorders.





Enhanced erythropoiesis of gene-modified erythroid cells in gene therapy for sickle cell disease (SCD). Truncated human erythropoietin receptor (thEpoR) enhances erythropoietin-mediated erythropoiesis in gene-modified cells, enabling improved therapeutic effect (such as fetal hemoglobin induction) in hematopoietic stem cell (HSC) gene therapy in SCD.