title: Kinetics and Signal Activation Properties of Circulating Factor(s) From Healthy Volunteers Undergoing Remote Ischemic Pre-Conditioning.
abstract: Although remote ischemic pre-conditioning (RIPC) reduced infarct size in animal experiments and proof-of-concept clinical trials, recent phase III trials failed to confirm cardioprotection during cardiac surgery. Here, we characterized the kinetic properties of humoral factors that are released after RIPC, as well as the signal transduction pathways that were responsible for cardioprotection in an ex vivo model of global ischemia reperfusion injury. Venous blood from 20 healthy volunteers was collected at baseline and 5 min, 30 min, 1 h, 6 h, and daily from 1 to 7 days after RIPC (3 × 5/5 min upper-limb ischemia/reperfusion). Plasma-dialysates (cut-off: 12 to 14 kDa; dilution: 1:20) were infused into Langendorff-perfused mouse hearts subjected to 20/120 min global ischemia/reperfusion. Infarct size and phosphorylation of signal transducer and activator of transcription (STAT)3, STAT5, extracellular-regulated kinase 1/2 and protein kinase B were determined. In a subgroup of plasma-dialysates, an inhibitor of STAT3 (Stattic) was used in mouse hearts. Perfusion with baseline-dialysate resulted in an infarct size of 39% of ventricular mass (interquartile range: 36% to 42%). Perfusion with dialysates obtained 5 min to 6 days after RIPC significantly reduced infarct size by ∼50% and increased STAT3 phosphorylation beyond that with baseline-dialysate. Inhibition of STAT3 abrogated these effects. These results suggest that RIPC induces the release of cardioprotective, dialyzable factor(s) within 5 min, and that circulate for up to 6 days. STAT3 is activated in murine myocardium by RIPC-induced human humoral factors and is causally involved in cardioprotection.
authors.affiliation: Institute for Pathophysiology, West-German Heart and Vascular Center Essen, University of Essen Medical School, Essen, Germany; Department of Cardiology of the West-German Heart and Vascular Center Essen, University of Essen Medical School, Essen, Germany.
authors.forename: Heike A
authors.initials: HA
authors.lastname: Hildebrandt
authors.affiliation: Institute for Pathophysiology, West-German Heart and Vascular Center Essen, University of Essen Medical School, Essen, Germany.
authors.forename: Vincent
authors.initials: V
authors.lastname: Kreienkamp
authors.affiliation: Institute for Pathophysiology, West-German Heart and Vascular Center Essen, University of Essen Medical School, Essen, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Gent
authors.affiliation: Department of Cardiology of the West-German Heart and Vascular Center Essen, University of Essen Medical School, Essen, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Kahlert
authors.affiliation: Institute for Pathophysiology, West-German Heart and Vascular Center Essen, University of Essen Medical School, Essen, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Heusch
authors.affiliation: Institute for Pathophysiology, West-German Heart and Vascular Center Essen, University of Essen Medical School, Essen, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Kleinbongard
keywords: AKT, protein kinase B; ERK, extracellular-regulated kinase; IQR, interquartile range; LV+RV, left and right ventricular; LVDP, left ventricular developed pressure; RIC, remote ischemic conditioning; RIPC, remote ischemic pre-conditioning; SAFE, survival activating factor enhancement; STAT, signal transducer and activator of transcription; TTC, 2,3,5-triphenyltetrazolium chloride; cardioprotection; human; humoral factor; kinetics; remote ischemic pre-conditioning; signaling