Preconditioning Promotes Survival and Angiomyogenic Potential of Mesenchymal Stem Cells in the Infarcted Heart via NF-κB Signaling

Abstract

We proposed that pharmacological manipulation of mesenchymal stem cells (MSCs) with diazoxide enhanced their survival and regenerative potential via NFκB regulation. MSCs preconditioned (^PCMSCs) with diazoxide and later subjected to oxidant stress with 100 μmol/L H₂O₂ either immediately or after 24 h exhibited higher survival (p < 0.01 vs nonpreconditioned MSCs; ^Non-PCMSCs) with concomitantly increased phosphorylation of PI3K, Akt, GSK3β (cytoplasmic), and NF-κB (p65) (nuclear). Akt kinase activity was determined as a function of GSK3β activity. Pretreatment of ^PCMSCs with Wortmannin (Wt), NEMO-binding domain (NBD), or NF-κB (p50) siRNA abolished NF-κB (p65) activity. Preconditioning increased NF-κB-dependent elevation of secretable growth factors associated with their paracrine effects. Inhibition of PI3K activity with Wt reduced ^PCMSCs viability at both early and 24 h time-points. However, inhibition of NF-κB reduced viability of ^PCMSCs only at 24 h time-point. For in vivo studies, DMEM without cells (group-1) or containing 1 × 10⁶ male ^Non-PCMSCs (group-2), ^PCMSCs (group-3), ^PCMSCs pretreated with Wortmannin (group-4) or NF-κB decoy (group-5) were transplanted in a female rat model of acute myocardial infarction. Group-3 showed highest cell survival and growth factor expression, increased angiomyogenesis, and functional improvement. We conclude that activation of NF-κB by preconditioning promoted ^PCMSCs survival and angiomyogenic potential in the infarcted heart. Antioxid. Redox Signal. 12, 693–702.