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Updated: Apr 22, 2026
A Model to Simulate Clinically Relevant Hypoxia in Humans
Published on: December 22, 2016
Simulated temporary hypoxia triggers the release of CD31+/Annexin+ endothelial microparticles: A prospective pilot
Michael Lichtenauer1, Bjoern Goebel2, Michael Fritzenwanger2
1Clinic of Internal Medicine II, Department of Cardiology, Paracelsus Medical University of Salzburg, Austria.
Introduction:
Endothelial microparticles (EMP) are small membrane vesicles that originate from activated or apoptotic endothelial cells. Although the exact mechanism of EMP function is still relatively unknown, it has been shown that they modulate inflammatory processes, coagulation and vascular function. In this study we hypothesized that transient hypoxia may act as a trigger for the release of EMP into circulation.
Materials And Methods:
Fourteen healthy volunteers were subjected to transient normobaric hypoxia in an air-conditioned chamber simulating an oxygen concentration of a height of up to 5500 meters. Blood samples were evaluated for EMP using flow cytometry.
Results:
During the experiment oxygen concentration was adjusted to a value equivalent to a height of 5500 meters to achieve hypoxic conditions. Oxygen saturation decreased to 78% . At the final height a significant increase of CD31+/Annexin+ EMP levels was evident (increase from 0.03% ± 0.01% SEM to 0.12% ± 0.04% SEM, p = 0.0188).
Conclusions:
These experimental results show that temporary hypoxic conditions can trigger the release of CD31+/ Annexin+ EMP also in healthy volunteers. In our previous studies we have shown that apoptotic bodies can confer pro-survival signals to cardiomyocytes during myocardial ischemia. Based on the experimental results of this current study we believe that the release of CD31+/Annexin+ EMP during hypoxia might act as an endogenous survival signal.
Insights
Transient hypoxia significantly increases endothelial microparticles (EMP) in healthy individuals. This suggests that EMP released during low oxygen conditions may serve as an endogenous survival signal, potentially protecting heart cells.
Area of Science:
- Cardiovascular Science
- Cell Biology
- Physiology
Background:
- Endothelial microparticles (EMP) are vesicles from activated or apoptotic endothelial cells.
- EMP are known to influence inflammation, coagulation, and vascular function.
- The precise role of EMP, especially under hypoxic stress, requires further investigation.
Purpose of the Study:
- To investigate if transient hypoxia triggers the release of endothelial microparticles (EMP) in healthy volunteers.
- To quantify the levels of CD31+/Annexin+ EMP under simulated high-altitude conditions.
Main Methods:
- Healthy volunteers underwent simulated high-altitude exposure (up to 5500m) inducing transient normobaric hypoxia.
- Blood samples were collected and analyzed for EMP using flow cytometry.
- Oxygen saturation levels were monitored throughout the experiment.
Main Results:
- Hypoxic conditions significantly reduced oxygen saturation to 78%.
- A significant increase in CD31+/Annexin+ EMP levels was observed (from 0.03% to 0.12%, p=0.0188).
- These findings demonstrate EMP release in response to acute hypoxia in healthy subjects.
Conclusions:
- Temporary hypoxic conditions stimulate the release of CD31+/Annexin+ EMP in healthy individuals.
- The release of EMP during hypoxia may function as an endogenous survival mechanism.
- Further research could explore the therapeutic potential of EMP in conditions like myocardial ischemia.
