Helium induced organ protection and the role of circulatory factors:
secretion of Caveolin to the bloodstream (HeCav) in humans.

Based on experimental and clinical data that show a profound organ protective
effect of the noble gas helium we here aim to investigate the underlying
mechanism of this effect using a translational approach. We hypothesize that
serum taken from volunteers subjected to 30 minutes of helium inhalation can
protect different cell types in vitro. Based on results showing that Caveolins
are secreted into the blood stream of different animal species after helium
inhalation we aim to investigate the role of these circulating factors in
mediating the protective effect of helium in humans.

The primary objective of this study is to investigate whether serum taken from
volunteers subjected to 30 minutes of helium inhalation can protect different
cell types against hypoxia-reperfusion induced damage and to investigate the
role of circulating Caveolins in mediating this protective effect.

Single center, explorative study with a cross-over design, using the principle
of balanced assignment.

All volunteers have to undergo two experimental *cycles*: one with heliox
inhalation (79% helium, 21% oxygen) and one with inhalation of normal room air.
Until now, no relevant cardiovascular, pulmonary, allergic or other side
effects of helium inhalation have been reported. A gas mixture of helium and
oxygen (heliox) is already used for clinical purposes, such as patients with
severe asthma or for children undergoing mechanical ventilation. Volunteers
will experience a transiently higher voice after helium inhalation Between the
experimental cycles there will be an episode of at least one week. One cycle
includes one whole day in the AMC (± 7 hours total stay) with blood withdrawal
at 3 different time points, and another blood withdrawal on the next day in the
morning (±24 h after inhalation), in total 4 times blood withdrawal for each
experimental cycle. On the day of participation, a physical examination
(cardiopulmonary system) will be performed by a physician. Twelve hours before
the start of the experimental cycle, the volunteer is not allowed to drink
coffee or other caffeine containing drinks, alcohol containing drinks or to
smoke. Doing any kind of sports on the night before the experimental day in the
AMC, or the night before the second day is also prohibited.
On the experimental day, the volunteers have to stay in the research room in
which circumstances will be as standardized as possible. Until after the helium
inhalation the volunteers have to stay seated in a chair and they will be
offered time to read or to watch video. After that, they will receive a lunch
that will be the same for every volunteer and the volunteers are allowed to
walk around but they have to stay within the AMC.
Each blood withdrawal will be taken by a separate venous puncture performed by
a physician with extensive experience in this field, such as an
anesthesiologist. For this study, the blood sampling cannot take place through
a venous access line. In former studies the venous access line often caused
problems during blood sampling which troubled measurements of parameters
afterwards. The volunteer gives approximately 29 ml blood per time point, after
centrifugation (to separate cells from the serum) approximately 15 ml blood
serum will be left to incubate the different cell types and to investigate the
expression levels of Caveolin in the serum and for laboratory test (Leucocyte
count, Hb, CRP). 116 ml for one experimental cycle (2 days) and a total of 232
ml for the whole experiment (4 days), spread over one to two weeks.