Abstract 5962: Adenoviral and Retroviral Transduction of the Thymidine Kinase PET Reporter Gene in Mesenchymal Stem Cells: Effect on Functional Parameters and Length of Expression
Background: We previously demonstrated that mesenchymal stem cells (MSCs) can be transduced with adenoviruses or retroviruses carrying the thymidine kinase PET reporter gene (PRG). In this study, we tested the effect of viral transduction on functional parameters of MSCs and we compared the length of transgene expression induced by the two viral vectors, in order to evaluate the use of this PRG for tracking MSCs after transplantation into the myocardium.
Methods: We infected rat MSCs with adenoviruses carrying the herpes simplex virus type-1 (HSV1) mutant thymidine kinase (tk) PET reporter gene (PRG) or with a retroviral construct expressing the wild type HSV1 tk PRG. The effect of viral transduction on cells viability and proliferation rate was evaluated by using the trypan blue assay and a mitochondrial dehydrogenase activity based fluorimetric assay, respectively. The capacity of differentiation was tested by inducing differentiation into the adipogenic and osteogenic lineages in both populations of transduced MSCs. The 3H-Penciclovir (3H-PCV) cell uptake in both infected MSCs populations was used to determine the length of the PRG expression after transduction.
Results: No modification of viability of the cells transduced with both vectors was observed by comparison to control MSCs (% of viability = 91±4.4, 95±3.5 and 94±4.3 [mean ± SD] for control, adeno- and retro- infected MSCs, respectively - p=NS for all comparison). Similarly, no statistical difference was found between the proliferation rate (mean increase of fluorescence units) of both populations of transduced MSCs by comparison to control MSCs. Both populations of transduced MSCs maintained their capacity to differentiate into adipogenic and osteogenic lineages as demonstrated by the Oil Red O and the Von Kossa staining. Finally, transduced MSCs exhibited a significantly higher 3H-PCV accumulation by comparison to control MSCs, until 1 week and 2 months after adenoviral and retroviral infection, respectively.
Conclusion: Our results demonstrate that functional characteristics of MSCs are maintained after adenoviral or retroviral transduction with the HSV1 tk PRG and support the use small animal PET to image the short and long term fate of MSCs after transplantation into the myocardium.