Objective　To explore a proper titer of RNA interference recombinant adenovirus Ad-shRNA-NgR transfecting ischemic region in rat brains for further study on gene therapy in cerebral ischemia. 　Methods　Three different titers (7.90×10

9

1.58×10

10

and 3.16×10

10

pfu/ml) of recombinant adenovirus were respectively injected into the ischemic region of middle cerebral artery occlusion (MCAO)/reperfusion rats (n=10) by stereotactic surgery. Green fluorescent protein (GFP) expression in each group was observed to measure transfection effic

iency of recombinant adenovirus in postoperative 48 h and 1 week. Inflammation was observed by HE staining. 　Results　Transfection efficiencies of recombinant adenovirus in high and medium titer injection group were similar

about 60% to 70%

both significantly higher than low titer group (P0.01). Besides

inflammation as perivascular infiltration of lymphoid and macrophage was only observed in high titer group. 　Conclusion　Medium titer (1.58×10

10

pfu/ml) of recombinant adenovirus can stably

with high efficiency and low toxicity

transfect ischemic brain tissue  in rats.