Changes in the Secretory Response of MMSCs after Interaction with Immune Cells of Healthy Volunteers under “Dry” Immersion Conditions

Multipotent mesenchymal stromal cells (MMSCs) have a high reparative potential, as well as the ability to modulate inflammation. An important role in the implementation of these properties is played by their soluble factors. The composition of the MMSC secretome depends on the microenvironment and can change in the presence of soluble mediators of immune cells. In this work, we investigated the secretory activity of MMSCs upon interaction in vitro with natural killer cells (NKs) and T lymphocytes isolated from the peripheral blood of healthy volunteers under 21-day “dry” immersion (DI). It was shown that, during co-culturing with immune cells, the secretion of a number of factors significantly increased. The level of the chemokines fractalkine and eotaxin, as well as the growth factors EGF and PDGF-AB/BB, increased on average three times. The factors FGF-2, G-CSF, GRO, and VEGF increased by tens and even hundreds of times. This may indicate “priming” of MMSCs by immunocytes. The intensity of the effect depended on the type of immune cells and changed during DI. When interacting with T cells, the stimulation of the secretory activity of MMSCs was weakened on the 21st day of DI, and with NKs on the seventh day of DI. The detected dynamics coincide with a change in the profile of the secretion of inflammatory factors by immunocytes, which indicates the reaction of MMSCs to the modification of the secretory activity of immune cells due to changes in the ability to respond to a activation after exposure DI.