A CLINICALLY APPLICABLE LENTIVIRAL VECTOR CORRECTS THE ANEMIA AND BONE MARROW FAILURE IN A MOUSE MODEL FOR DIAMOND-BLACKFAN ANEMIA

Diamond-Blackfan Anemia (DBA) is a congenital erythroid hypoplasia caused by dysfunction of genes coding for ribosomal proteins. The ribosomal protein S19 (RPS19) gene is the most frequently mutated. Our previous studies showed that gene therapy with autologous HSCs modified to express RPS19 represents a potential therapeutic option. Here, we assessed the efficacy of a clinically applicable single gene lentiviral vector with a good safety profile for treatment of RPS19-deficient DBA. We designed a lentiviral vector harbouring a codon-optimized human RPS19 cDNA driven by the shortened version of the human elongation factor 1α (EFS) promoter. We transduced c-Kit+ bone marrow cells isolated from our established doxycycline inducible RPS19-deficient DBA mouse model and injected cells into lethally irradiated wild-type mice (Vector). The recipients transplanted with mock transduced c-Kit+ bone marrow cells from DBA mice were regarded as Mock group. After transplantation, cells were engrafted for 2 months, followed by doxycycline induction to recipients to induce DBA phenotype. The age matched wild-type mice receiving no irradiation and transplantation but same doxycycline induction concentration were regarded as control group (WT). The short-term effect of vector was analysed at 2 weeks after doxycycline induction. In Vector group, all recipients showed normal blood cellularity (RBC:10.79±1.05 × 109/L, Hb:162.75±5.26g/L) comparing with WT group (RBC:8.55±1.03 × 109/L, Hb:162±2.45g/L), while in Mock group, half of mice died due to dramatic BM failure and rest of mice showed DBA phenotype (RBC:4.74±2.2 × 109/L, Hb:79.13±34.24g/L). Our results demonstrate the feasibility and preclinical efficacy for treatment of DBA by using lentiviral vector. The long-term effects (16 weeks) and analysis of vector integration sites are in progress.