Ischemia/Reperfusion Injury Protection by Mesenchymal Stem Cell Derived Antioxidant Capacity

Abstract

Mesenchymal stem cell (MSC) transplantation after ischemia/reperfusion (I/R) injury reduces infarct size and improves cardiac function. We used mouse ventricular myocytes (VMs) in an in vitro model of I/R to determine the mechanism by which MSCs prevent reperfusion injury by paracrine signaling. Exposure of mouse VMs to an ischemic challenge depolarized their mitochondrial membrane potential (J mito ), increased their diastolic Ca 2 + , and significantly attenuated cell shortening. Reperfusion of VMs with Ctrl tyrode or MSC-conditioned tyrode (ConT) resulted in a transient increase of the Ca 2 + transient amplitudes in all cells. ConT-reperfused cells exhibited a decreased number early after depolarization (EADs) (ConT: 6.3% vs. Ctrl: 28.4%) and prolonged survival (ConT: 58% vs. Ctrl: 33%). J mito rapidly recovered in Ctrl as well as ConT-treated VMs on reperfusion; however, in Ctrl solution, an exaggerated hyperpolarization of J mito was determined that preceded the collapse of J mito . The ability of ConT to attenuate the hyperpolarization of J mito was suppressed on inhibition of the PI3K/Akt signaling pathway or I K,ATP . However, protection of J mito was best mimicked by the reactive oxygen species (ROS) scavenger mitoTEMPO. Analysis of ConT revealed a significant antioxidant capacity that was linked to the presence of extracellular superoxide dismutase (SOD3) in ConT. In conclusion, MSC ConT protects VMs from simulated I/R injury by its SOD3-mediated antioxidant capacity and by delaying the recovery of J mito through Akt-mediated opening of I K,ATP . These changes attenuate reperfusion-induced ROS production and prevent the opening of the permeability transition pore and arrhythmic Ca 2 + release.

p21-Activated kinase1 (Pak1) is a negative regulator of NADPH-oxidase 2 in ventricular myocytes

“…Ventricular myocytes were isolated from 3-6 month old WT and Pak1 knockout mice (Pak1 -/- ) by Langendorff perfusion as previously described [21,24]. All animal procedures were performed with the approval of the IACUC of the University of Illinois at Chicago and in accordance with the National Institute of Health's Guide for the Care and Use of Laboratory Animals.…”

“…Since changes in cardiac E-CC play a prominent role in ischemia-induced arrhythmic activity we aimed to test the hypothesis that under ischemic conditions Pak1 signaling regulates cellular Ca 2+ handling properties thereby preventing the induction of arrhythmia. We used isolated VMs from WT and Pak1 -/- mice [20-22] that were exposed to simulated ischemia while we monitored excitation-induced Ca 2+ handling properties [21,23,24]. Our experimental results demonstrate that attenuation of Pak1 signaling increases the cardiomyocytes propensity for Ca 2+ -overload.…”

The physiology of blood platelets and changes of their biological activities in multiple sclerosis

“…Many drugs in clinical practice or currently in trial target this mechanism. Stem cells, specifically mesenchymal stem cells (MSCs) therapies could offer an alternative source of antioxidant capability (DeSantiago et al 2013). …”

The Role of Antioxidation and Immunomodulation in Postnatal Multipotent Stem Cell-Mediated Cardiac Repair

“…Additionally, the paracrine mechanism by which MSCs protect cardiomyocyte following ischemia/reperfusion (I/R) injury was further demonstrated by Desantiago et al . using an in vitro model of I/R [69]. Reperfusion of mouse cardiomyocytes with MSC-conditioned tyrode (MSC-ConT) led to a decreased number of attenuated cardiomyocyte shortening that resulted from depolarization of mitochondrial membrane potential and subsequent increase of diastolic Ca 2+ as well as prolonged cardiomyocyte survival.…”