Non-invasive Bioluminescence Imaging of Myoblast-Mediated Hypoxia-Inducible Factor-1 Alpha Gene Transfer

Purpose: We tested a novel imaging strategy, in which both the survival of transplanted myoblasts and their therapeutic transgene expression, a recombinant hypoxia-inducible factor-1 alpha (HIF-1 alpha-VP2), can be monitored using firefly luciferase (fluc) and Renilla luciferase (hrl) bioluminescence reporter genes, respectively. Procedures: The plasmid pUbi-hrl-pUbi-HIF-1 alpha-VP2, which expresses both hrl and HIF-1 alpha-VP2 using two ubiquitin promoters, was characterized in vitro. C2c12 myoblasts stably expressing fluc and transiently transfected with pUbi-hrl-pUbi-HIF-1 alpha-VP2 were injected into the mouse hindlimb. Both hrl and fluc expression were monitored using bioluminescence imaging (BLI). Results: Strong correlations existed between the expression of hRL and each of HIF-1 alpha-VP2, VEGF, and PlGF (r (2) > 0.83, r (2) > 0.82, and r (2) > 0.97, respectively). In vivo, both transplanted cells and HIF-1 alpha-VP2 transgene expression were successfully imaged using BLI. Conclusions: An objective evaluation of myoblast-mediated gene transfer in living mice can be performed by monitoring both the survival and the transgene expression of transplanted myoblasts using the techniques developed herein.