Multiply attenuated, self-inactivating lentiviral vectors efficiently deliver and express genes for extended periods of time in adult XXXX cardiomyocytes in vivo.

@entity2858 @entity9221 @entity35 @entity2834
BACKGROUND: Among retroviral vectors, lentiviral vectors are unique in that they transduce genes into both dividing and nondividing cells. However, their ability to provide sustained myocardial transgene expression has not been evaluated. METHODS AND RESULTS: Multiply attenuated, self-inactivating lentivectors based on @entity2858 contained the enhanced green fluorescent protein (EGFP) gene under the transcriptional control of either the cytomegalovirus ( @entity2834 ) immediate-early enhancer/promoter, the elongation factor-1alpha ( @entity9221 ) promoter, or the phosphoglycerate-kinase (PGK) promoter. Lentivectors transduced adult @entity35 cardiomyocytes in a dose-dependent manner (transduction rates, >90%; multiplicity of infection, approximately 5). The @entity2834 promoter achieved higher EGFP expression levels than the @entity9221 and PGK promoters. Insertion of the central polypurine tract pol sequence improved gene transfer efficiency by approximately 2-fold. In vivo gene transfer kinetics was studied by measuring the copy number of integrated lentivirus DNA and EGFP concentrations in cardiac extracts by real-time polymerase chain reaction and ELISA, respectively. With @entity2834 promoter-containing lentivectors, vector DNA peaked at day 3, declined by approximately 4-fold at day 14, but then remained stable up to week 10. Similarly, EGFP expression peaked at day 7, decreased by approximately 7-fold at day 14, but was essentially stable thereafter. In contrast, vector DNA and EGFP expression declined rapidly with @entity9221 promoter-containing lentivectors. Peak EGFP expression with titer-matched adenovectors was approximately 35% higher than with @entity2834 lentivectors but was lost rapidly over time. CONCLUSIONS: Lentivectors efficiently transduce and express genes for extended periods of time in cardiomyocytes in vivo. Lentivectors provide a useful tool for studying myocardial biology and a potential system for gene heart therapy.
