Abstract WMP74: Therapeutic Effect of Human Dental Pulp Stem Cells Overexpressing Hepatocyte Growth Factor in Experimental Ischemic Stroke

Abstract

Objective: Human dental pulp stem cell (DPSC) is an attractive cell source because they can be easily obtained as medical waste without ethical and logistical problems. Transplantation of DPSC decreases tissue injury in the rat brain and enhances motor function recovery after the middle cerebral artery occlusion (MCAO). We aimed increasing therapeutic effects combining DPSC and ex vivo human hepatocyte growth factor (HGF) gene transfer with adeno-associated virus (AAV) vector. Methods: Male Sprague-Dawley rats were subjected to transient 90 minute MCAO, followed by intravenous administration of 1 x 10 6 cells of DPSC, AAV-1/HGF transferred DPSC (DPSC/HGF) or vehicle immediately after reperfusion (each, n=8). Infarct volumes, neurological deficits and immunochemistry were assessed at 24 and 72 h after reperfusion. We also detected concentrations of TNF-α and IL-1β in the brain tissue extracts from the ischemic hemisphere by ELISA. Results: Infarct volumes at 24 h after reperfusion were diminished in both DPSC (155.7 ± 35.6 mm 3 , p < 0.01) and DPSC/HGF (110.2 ± 34.7 mm 3 , p < 0.01) transplantation compared with vehicle (213.1 ± 29.1 mm 3 ). DPSC/HGF transplantation showed more reduction of infarct volume compared with DPSC (110.2 ± 34.7 mm 3 vs 155.7 ± 35.6 mm 3 , p < 0.05). Motor function recovery was also observed at 24 and 72 h by both DPSC and DPSC/HGF transplantation. Furthermore, we determined that DPSC/HGF transplantation significantly suppressed expression of Iba-1 and TNF-α compared with DPSC in the cortical ischemic boundary zone (p < 0.05, p < 0.01). Also, DPSC/HGF markedly decreased brain tissue TNF-α (11.5 ± 4.2 pg/ml) and IL-1β (22.2 ± 4.2 pg/ml) concentrations compared with vehicle (TNF-α, 54.6 ± 9.8 pg/ml, p < 0.01; IL-1β, 95.2 ± 9.8 pg/ml, p < 0.01) and DPSC (TNF-α, 26.8 ± 11.2 pg/ml, p < 0.05; IL-1β, 40.6 ± 11.2 pg/ml, p < 0.05) in the ischemic hemisphere. Both DPSC and DPSC/HGF group improved neuronal degeneration compared with vehicle (p < 0.05, p < 0.01). Conclusions: These findings show that overexpression of HGF by AAV vector would enhance the neuroprotective effects of DPSC transplantation through the modulation of inflammation after acute ischemic stroke.