Increased levels of circulating progenitor cells after 1-week sojourn at moderate altitude (Austrian Moderate Altitude Study II, AMAS II).

We wanted to test if a sojourn at moderate altitude can activate circulation of adult progenitor cells in healthy individuals. Thus, we investigated 11 healthy volunteers, who spent 1-week at 1700 m (Oberlech, Austria,) simulating an active holiday. We measured circulating CD34(+) progenitor cell populations by flow cytometry and cytokines (using ELISA) in peripheral blood at baseline (500 m) and at the end of the sojourn. Extent of physical activity was documented via armband. CD34(+)CXCR-4(+) cells significantly increased in peripheral blood after the sojourn. CD34(+)CD31(+) and CD34(+)CD133(+) cells were upregulated in trend. Levels of SDF-1, G-CSF and VEGF decreased in trend whereas erythropoietin and SCF remained equal. Progenitor cells and degree of daily physical exercise did not correlate. We present the first study showing that exposure to moderate altitude with physical activity leads to increased levels of circulating progenitor cells. This effect may be due to hypoxia and/or physical activity.