Heme Oxygenase-1 Gene Therapy in a Murine Model of Sickle Cell Disease.

Abstract 1527

Poster Board I-550

We previously demonstrated that increases in heme oxygenase-1 (HO-1) and its products, carbon monoxide and biliverdin, inhibit inflammation and vasoocclusion in mouse models of sickle cell disease (SCD). In this study, an albumin promoter driven Sleeping Beauty transposase plasmid with a wild type rat hmox-1 gene (wt-HO-1) transposable element (289 amino acids) was delivered by hydrodynamic tail vein injections to SCD mice. Eight weeks after injection, SCD mice had 3-fold increases in HO-1 activity in their livers, similar to hemin-treated mice. mRNA transcription of the transposable element was confirmed by qRT-PCR RFLP analysis. HO-1 overexpressing mice had marked activation of the phospho-p38 MAPK and phospho-Akt proteins and decreased NF-kB p65 in liver nuclear extracts. Hypoxia-induced stasis, a characteristic of SCD but not normal mice, was inhibited in dorsal skin fold chambers in wt-HO-1 SCD mice. None of these effects were seen in SCD mice injected with Sleeping Beauty containing a nonsense rat hmox-1 gene (ns-HO-1) that encodes for amino acids 1-241 with little or no enzymatic activity. Immunohistochemistry of HO-1 in livers demonstrated perinuclear HO-1 staining in both hepatocytes and sinusoidal Kupffer cells in wt- and ns-HO-1-treated mice. We conclude HO-1 gene therapy targeted to the liver is beneficial in SCD by activating cytoprotective signaling pathways and inhibiting vascular stasis at sites distal to transgene expression.