Comparison of human sodium iodide symporter (hNIS) gene expression between lentiviral and adenoviral vectors in rat mesenchymal stem cell

Quantitative comparison of transgene expression within stem cells between lentivirus and adenovirus-mediated delivery systems has not been done. Here, we evaluated the human sodium iodide symporter (hNIS) gene expression in rat mesenchymal stem cell (rMSC) transduced by lentivirus or adenovirus, and compared the hNIS expression quantitatively between the two delivery systems. Lentiviral-mediated stably hNIS expressing rMSC (lenti-hNIS-rMSC) was constructed by cloning the hNIS gene into pLenti6/UbC/V5-DEST (Invitrogen) to obtain pLenti-hNIS, transducing rMSC with the pLenti-hNIS, and selecting with blasticidin for 3 weeks. Recombinant adenovirus expressing hNIS gene (Rad-hNIS) was produced by homologous recombination and Rad-hNIS transduced rMSC (adeno-hNIS-rMSC) was evaluated for the hNIS expression 48 hours post infection at MOI 1, 5, 20, 50, and 100. The hNIS expression in lenti-hNIS-rMSC or adeno-hNIS-rMSC was assessed by immunocytochemistry, western blot, and I-125 uptake. Immunocytochemistry using mono-clonal anti-hNIS antibody revealed that intensity of hNIS immunoreactivity in lenti-hNIS-rMSC was greater than that in adeno-hNIS-rMSC at MOl 20 but lower than that at MOl 50. Western blot analysis also showed that lenti-hNIS-rMSC was intermediate between adeno-hNIS-rMSCs at MOl 20 and 50 in hNIS expression. However in vitro I-125 uptake test demonstrated that iodide uptake in lenti-hNIS-rMSC (297046659 picomole/106 cells) was greater than that in adeno-hNIS-rMSC at MOI 100 (61682134 picomole/106 cells). These results suggest that lentivirus mediated hNIS expression is greater in terms of hNIS function but lower in terms of hNIS protein amount than adenovirus mediated hNIS expression 48 hours post infection. Stem cell tracking using hNIS as a reporter gene should be conducted in consideration of relative viral efficiency of transgene expression