A recombinant adenovirus Ad5-sr39tk-IRES-VEGF165(Ad5-SIV) was constructed in our lab

using mutant simplex herpes viral thymidine kinase reporter gene(HSV1-sr39tk) as a report gene

and human vascular endothelial growth factor 165(VEGF165) as a therapeutic gene.A replication-defective adenovirus carrying the enhanced green fluorescent protein gene(Ad5-EGFP) was used as a control.MSCs were infected with Ad5-SIV at different multiplicity of infection(MOI = 0

10

25

50

75 and 100).The expression of HSV1-sr39tk and VEGF165 was detected by immunofluorescence

and the secretion of VEGF was detected by enzyme-linked immunosorbent assay(ELISA).The cellular uptake of 131I-FIAU was performed to detect the expression of HSV1-sr39tk.The immunofluorescence showed HSV1-sr39tk and VEGF165 protein could express successfully at Ad5-SIV-infected MSCs.The cellular uptake of 131I-FIAU increased with the virus titer(P<0.05).The time dependent uptake showed uptake rates increased rapidly from 30 min to 150 min

with a plateau after 150 min.ELISA results showed VEGF165 protein secretion increased with the titer(P<0.05).The VEGF165 protein secretion correlated highly with the uptake rate of 131I-FIAU(P<0.05).In conclusion

HSV1-sr39tk and VEGF165 could express successfully after MSCs were infected with Ad5-SIV.The expression of therapy gene correlated significantly with the reporter gene.This provides a theoretical basis for in vitro nuclear reporter gene imaging with this system.