Acute effects of remote ischemic preconditioning on cutaneous microcirculation - a controlled prospective cohort study

<p>Abstract</p> <p>Background</p> <p>Therapeutic strategies aiming to reduce ischemia/reperfusion injury by conditioning tissue tolerance against ischemia appear attractive not only from a scientific perspective, but also in clinics. Although previous studies indicate that remote ischemic intermittent preconditioning (RIPC) is a systemic phenomenon, only a few studies have focused on the elucidation of its mechanisms of action especially in the clinical setting. Therefore, the aim of this study is to evaluate the acute microcirculatory effects of remote ischemic preconditioning on a distinct cutaneous location at the lower extremity which is typically used as a harvesting site for free flap reconstructive surgery in a human in-vivo setting.</p> <p>Methods</p> <p>Microcirculatory data of 27 healthy subjects (25 males, age 24 ± 4 years, BMI 23.3) were evaluated continuously at the anterolateral aspect of the left thigh during RIPC using combined Laser-Doppler and photospectrometry (Oxygen-to-see, Lea Medizintechnik, Germany). After baseline microcirculatory measurement, remote ischemia was induced using a tourniquet on the contralateral upper arm for three cycles of 5 min.</p> <p>Results</p> <p>After RIPC, tissue oxygen saturation and capillary blood flow increased up to 29% and 35% during the third reperfusion phase versus baseline measurement, respectively (both p = 0.001). Postcapillary venous filling pressure decreased statistically significant by 16% during second reperfusion phase (p = 0.028).</p> <p>Conclusion</p> <p>Remote intermittent ischemic preconditioning affects cutaneous tissue oxygen saturation, arterial capillary blood flow and postcapillary venous filling pressure at a remote cutaneous location of the lower extremity. To what extent remote preconditioning might ameliorate reperfusion injury in soft tissue trauma or free flap transplantation further clinical trials have to evaluate.</p> <p>Trial registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01235286">NCT01235286</a></p

The effect of transient oxygenation on stem cell mobilization and ischemia/reperfusion heart injury

For general anesthesia, pre-oxygenation is routinely performed prior to intubation. It is well-known that ischemic/hypoxic preconditioning induces stem cell mobilization and protects against ischemia/reperfusion (I/R) injury. In this study, we investigated the effect of transient oxygenation on stem cell mobilization and I/R injury of the heart. Mice were exposed to 100% oxygen for 5 or 20 minutes. We evaluated the number of c-kit+ stem/progenitor cells and the levels of SDF-1α and VEGF in peripheral blood at 1, 3, 6, and 24 hours after oxygenation. We also induced I/R injury of the heart at 3 hours post-oxygenation for 5 minutes and then examined stem cell recruitment and fibrotic changes in the heart 3 or 14 days later. The number of c-kit+ cells in peripheral blood was significantly increased at 1 or 24 hours after oxygenation for either 5 or 20 minutes. Oxygenation for 5 or 20 minutes did not significantly change the SDF-1α level measured in plasma. However, the plasma VEGF level was decreased at 3 hours post-oxygenation for 20 minutes (p = 0.051). Oxygenation for 5 minutes did not significantly alter the fibrotic area or cell apoptosis. Although oxygenation for 5 minutes increased the number of c-kit+ cells in hearts damaged by I/R injury, this difference was not significant between groups due to large variation between individuals (p = 0.14). Although transient oxygenation induces stem cell mobilization, it does not appear to protect against I/R injury of the heart in mice