Restoration of hemoglobin A synthesis in erythroid cells from peripheral blood of thalassemic patients

Mononuclear cells from peripheral blood of thalassemic patients were treated with morpholino oligonucleotides antisense to aberrant splice sites in mutant beta-globin precursor mRNAs (pre-mRNAs). The oligonucleotides restored correct splicing and translation of beta-globin mRNA, increasing the hemoglobin (Hb) A synthesis in erythroid cells from patients with IVS2-654/beta(E), IVS2-745/IVS2-745, and IVS2-745/IVS2-1 genotypes. The maximal Hb A level for repaired IVS2-745 mutation was approximately 30% of normal; Hb A was still detectable 9 days after a single treatment with oligonucleotide. Thus, expression of defective beta-globin genes was repaired and significant level of Hb A was restored in a cell population that would be targeted in clinical applications of this approach.