Effect of intermittent hypobaric hypoxia on induced muscle injury repair in laboratory rats

Abstract

Our work hypothesis is that hypobaric hypoxia exposure can be a stimulus for the mobilization and increase of hematopoietic stem cells (HSC) in peripheral circulation. Once stem cells has the capacity to self-renew and differentiate it is indisputable its role in muscle regeneration process. Therefore the aim of this study is to establish the possible efficiency of intermittent hypobaric hypoxia (IHHE) in the recovery of induced muscle damage in rats. Muscle damage was induced in rat posterior limbs by means of one session of downhill forced running according to well-known and accepted protocols. Control (Ctrl) animals followed a passive recovery by means of sedentary behavior. Both experimental groups were submitted to hypobaric hypoxia exposure. The difference between the two experimental groups was that the first group (HIP) followed only the IHHE protocol, whilst the second experimental group (EHIP) was submitted to IHHE and, in addition, an exercise protocol. In order to have a clear observation of the evolution of recuperation period the samplings were made one day before damage (T0), one day after damage (T1), three days after damage (T3), seven days after damage (T7) and fourteen days after damage (T14). Stem cells were assessed by flow cytometry with CD34-PE and CD45-FITC antibodies, with a protocol that was optimized with the time. Despite of the few samples number for group there are evidences of the effect of hypoxia in the increase of circulating stem cells and in the inflammatory response. These results open a new therapeutic strategy not only for the reparation of tissue lesions in athletes but also in other fields of medicine.