In vivo monitoring of adult neural stem cells (F3) using hNIS reporter gene in rat MCAo model

Abstract

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Objectives: Gene transfer is usually difficult in stem cells, and retrovirus has been suggested as a solution. For imaging of stem cell non-invasively in vivo using nuclear method, we developed the human sodium/iodide symporter (hNIS) gene delivery system using retrovirus for monitoring of neural stem cells in brain ischemic model.

Methods: hNIS gene was cloned into pLHCX vector. For packaging, viral vector co-transfected with envelope vector in GP2-293 cells. HB1.F3 neural stem cells were cultured in DMEM medium supplemented with 5% FBS and 5% HS. Retrovirus infected into F3 and hygromycine resistant cells were selected. F3-hNIS cells were tested functional hNIS expression by radioiodine uptake assay. Transient MCAo (Middle cerebral artery occulusion) was induced in the right middle cerebral artery of rat for 90 min. After 24 hr, F3-hNIS cells were injected into i.v. Scintigraphic image of 99mTc were obtained using γ-camera. The mRNA levels were assessed by RT-PCR analysis.

Results: The F3-hNIS cells showed an excellent correlation between radioiodine uptake and cell number (R2=0.96, p<0.005). The functional hNIS expression was maintained during continuous subculture (more than 10 times). Higher uptake of 99mTc was observed in F3-hNIS group than control. Compared to right brain, the ratio of uptake in left brain of F3-hNIS group was about 1.35 fold that of about 1.1 fold in control group. The hNIS mRNA was confirmed in left brain tissue of F3-hNIS group.

Conclusions: hNIS reporter system using retrovirus worked well in F3 neural stem cells. F3-hNIS cells were observed in ischemic lesion of animal model. This system could be useful for stem cell monitoring and trafficking in real time in vivo.

Research Support: SC3070