Adenoviral-mediated high efficiency expression of enhanced green fluorescence protein gene in ex vivo expanded rat mesenchymal stem cells

AIM:To investigate the feasibility and infection efficiency of MSCs with replication-deficient adenovirus containing delivered gene, and whether enhanced green fluorescence protein (EGFP) gene track the change during rMSCs differentiating neuron-like cells. METHODS: Rat marrow mesenchymal stem cells (rMSCs) were expanded in low density in vitro. Under the control of CMV promoter, pAd-EGFP-Vector was constructed by homologous recombination in E.coil BJ 5183, and the recombinant virus was produced in HEK 293 packaging cell line. rMSCs infected with Ad-EGFP were observed and analyzed with fluorescence microscope. Infection efficiency was assessed by microscopical scoring and flow cytometrics. After withdrawing serum and exposure to β-mercaptoethanol medium, rMSCs infected with Ad-EGFP was induced to differentiate into neuron-like cells. As a control, the plasmid of pTrack-EGFP also was transfected into rMSCs to evaluate transfection efficiency. RESULTS:The results showed that Adenovirus vector (AdVec) delivered EGFP gene with high efficiency to marrow mesenchymal stem cells. Gene expression analysis showed that 36%±2 % of rMSCs infected with recombinant adenovirus expressed the transgene of EGFP at high levels. However, the transfection of plasmid pTrack-EGFP using routine method of lipofectamin mixed with plasmid DNA (pTrack-EGFP) was not easily successful and the transfection efficiency was much lower. rMSCs infected with Ad-EGFP in different passage could differentiate into typical morphology alike neural cells after withdrawing serum and exposure to β-mercaptoethanol medium. Immuno-staining with neuron-specific enolase (NSE), a neuronal marker, was strong positive, which suggested that rMSCs infected with Ad-EGFP had the potential to differentiate into neurons or neuron-like cells. CONCLUSION:The AdVec system can deliver target gene into MSCs and EGFP gene carried by AdVec can track the change during rMSCs differentiating into neuron-like cells.