Engineered U7 Small Nuclear RNA Restores Correct ß-Globin Pre-mRNA Splicing in Mouse ßIVS2-654-Thalassemic Erythroid Progenitor Cells.

Restoration of correct splicing of ßIVS2-654-globin pre-mRNA was previously accomplished in erythroid cells from ß-thalassemia/HbE patients by an engineered U7 small nuclear RNA (snRNA) that carried a sequence targeted to the cryptic branch point and an exonic splicing enhancer, U7.BP+623 snRNA. In this study, this approach was tested in thalassemic mice carrying the ßIVS2-654 mutation. While correction of ßIVS2-654 pre-mRNA splicing was achieved in erythroid progenitors transduced with a lentiviral vector carrying the U7.BP+623 snRNA, a high level of truncated U7.BP+623 snRNA was also observed. The discrepancy of processing of the modified U7 snRNA in human and mouse constructs hamper the evaluation of pathologic improvement in mouse model.