Abstract 17949: Molecular Imaging of Regulation of mTORC1-S6K Signal Pathway of Mesenchymal Stem Cells in Alleviating Mice Cardiac Dysfunction Induced from Sepsis
Objective: Sepsis remains a major cause of morbidity and mortality in the patient suffered from severe trauma. Recent animal studies revealed that mesenchymal stem cells (MSCs) may be useful therapeutic adjuncts for tissue repairing. This study was designed to evaluate therapeutic efficacy and mechanism of mesenchymal stem cells in sepsis induced mice cardiac dysfunction(SICD).
Methods: Mesenchymal stem cells (MSCs) stably expressing firefly luciferase (Fluc) were isolated from ß-actin-Fluc transgenic FVB mice. Eight week-old wild type mice (WT) of cardiac-specific Raptor knockout mice were subjected to administration of LPS (20mg/kg) and inoculated intraperitoneally with MSCs (1х106). Cell survival and proliferation were assessed by bioluminescent imaging (BLI). Echocardiogram was performed for analysis of cardiac function. H9C2 Cells were exposed to LPS(10-4mol/L)for 24 hours and co-cultured with or without MSCs. Apoptosis was evaluated by TUNEL staining. The expressions of mTOR, p-mTOR, Raptor, Rictor, Akt, pAkt, NF-Kb analyzed by Western blot.
Results: In vivo BLI revealed 80% acute donor cell death of MSCs within 7 days after transplantation. ECG showed that systolic function in both WT and Raptor-KO groups was reduced 24 hours after sepsis compared with baseline. However, systolic function of Raptor KO group treated with MSC was relatively well preserved (P<0.05). In vitro cell study revealed that Raptor knock-down could promote survival of H9C2 exposed to LPS, which was accompanied by mTORC2 activation (P<0.05). On the contrary, Down regulation of Raptor inhibited apoptosis during LPS treatment accompanied by the activation of Akt and inhibition of S6k.
Conclusion: Inhibition of Raptor alleviate mice’s SICDand exerts beneficial effects on the therapeutic efficacy of MSCs in septic mice . The possible mechanism is through activation of and mTORC2-Akt and inhibition of mTORC1-S6K signal pathways which may lead to suppression of TNF-a and IL-1β.
Author Disclosures: W. Huang: None.
- © 2014 by American Heart Association, Inc.