No abstract

Storage protocols of vascular grafts need further improvement against ischemia-reperfusion (IR) injury. Hypoxia elicits a variety of complex cellular responses by altering the activity of many signaling pathways, such as the oxygen-dependent prolylhyroxylase domain-containing enzyme (PHD). Reduction of PHD activity during hypoxia leads to stabilization and accumulation of hypoxia inducible factor (HIF) 1a. We examined the effects of PHD inhibiton by dimethyloxalylglycine on the vasomotor responses of isolated rat aorta and aortic vascular smooth muscle cells (VSMCs) in a model of cold ischemia/warm reperfusion. Aortic segments underwent 24 hours of cold ischemic preservation in saline or DMOG (dimethyloxalylglycine)-supplemented saline solution. We investigated endothelium-dependent and -independent vasorelaxations. To simulate IR injury, hypochlorite (NaOCl) was added during warm reperfusion. VSMCs were incubated in NaCl or DMOG solution at 4°C for 24 hours after the medium was changed for a supplied standard medium at 37°C for 6 hours. Apoptosis was assessed using the TUNEL method. Gene expression analysis was performed using quantitative real-time polymerase chain reaction. Cold ischemic preservation and NaOCl induced severe endothelial dysfunction, which was significantly improved by DMOG supplementation (maximal relaxation of aortic segments to acetylcholine: control 95% 6 1% versus NaOCl 44% 6 4% versus DMOG 68% 6 5%). Number of TUNEL-positive cell nuclei was significantly higher in the NaOCl group, and DMOG treatment significantly decreased apoptosis. Inducible heme-oxygenase 1 mRNA expressions were significantly higher in the DMOG group. Pharmacological modulation of oxygen sensing system by DMOG in an in vitro model of vascular IR effectively preserved endothelial function. Inhibition of PHDs could therefore be a new therapeutic avenue for protecting endothelium and vascular muscle cells against IR injury.

BackgroundAlthough, ischemia/reperfusion induced vascular dysfunction has been widely described, no comparative study of in vivo- and in vitro-models exist. In this study, we provide a direct comparison between models (A) ischemic storage and in-vitro reoxygenation (B) ischemic storage and in vitro reperfusion (C) ischemic storage and in-vivo reperfusion.Methods and ResultsAortic arches from rats were stored for 2 hours in saline. Arches were then (A) in vitro reoxygenated (B) in vitro incubated in hypochlorite for 30 minutes (C) in vivo reperfused after heterotransplantation (2, 24 hours and 7 days reperfusion). Endothelium-dependent and independent vasorelaxations were assessed in organ bath. DNA strand breaks were assessed by TUNEL-method, mRNA expressions (caspase-3, bax, bcl-2, eNOS) by quantitative real-time PCR, proteins by Western blot analysis and the expression of CD-31 by immunochemistry. Endothelium-dependent maximal relaxation was drastically reduced in the in-vivo models compared to ischemic storage and in-vitro reperfusion group, and no difference showed between ischemic storage and control group. CD31-staining showed significantly lower endothelium surface ratio in-vivo, which correlated with TUNEL-positive ratio. Increased mRNA and protein levels of pro- and anti-apoptotic gens indicated a significantly higher damage in the in-vivo models.ConclusionEven short-period of ischemia induces severe endothelial damage (in-vivo reperfusion model). In-vitro models of ischemia-reperfusion injury can be limitedly suited for reliable investigations. Time course of endothelial stunning is also described.

Our results support the view that impairment of intracellular cGMP signalling plays a role in the pathogenesis of the endothelial dysfunction induced by cold storage warm reperfusion, which can be effectively reversed by pharmacological phosphodiesterase-5 inhibition.

Die Industrie 4.0, Digitalisierung und Automatisierung haben das Potenzial, den Werkstoff Stahlbeton unter anderem in Hinblick auf Ressourcenschonung, Vorfertigung, Dauerhaftigkeit, Qualität der Ausführung sowie viele weitere Aspekte entscheidend weiterzuentwickeln. Bereits jetzt können in Fertigungshallen immer häufiger Roboter und Robomaschinen angetroffen werden. In Anlehnung an diesen Trend werden im vorliegenden Beitrag derzeit durchgeführte Forschungs‐ und Entwicklungsarbeiten der Firmengruppe Max Bögl und der Universität der Bundeswehr München, Institut für Konstruktiven Ingenieurbau, vorgestellt. Die ersten erklärten Entwicklungsziele dieses Verbunds betreffen die Implementierung von Treibern der Digitalisierung und der Industrie 4.0 in die Planung und Herstellung von Stahlbetonfertigteilen. Hierzu wird in der digitalen Planung ein Prozess zur parametrischen 3D‐Modellierung und Bahnplanung für Roboteranwendungen entwickelt. Die entstehenden Datensätze werden anschließend in der technischen Umsetzung unter Verwendung von Industrierobotern einerseits zur individuellen Fertigung von Bewehrungskörben, andererseits zur Herstellung alternativer Bauteilgeometrien mittels eines Beton‐3D‐Druck‐Verfahrens verwendet.