Abstract: Wharton’s jelly mesenchymal stem cells (WJ-MSCs) exhibit most of the regenerative and differentiative properties of embryonic stem cells, raising no ethical issues and easily to collect. Under stressing conditions, they can lose these properties, undergoing premature senescence or apoptotic events. Simulated microgravity negatively impacts the physiology of the human body, influencing cell behavior, in growth and differentiation processes. Each cell responds to stress in several ways, generally by activating signaling pathways promoting survival or apoptosis. The kind of response also depends on the type and duration of the stressing event. Radio Electric Asymmetric Conveyer (REAC) biomodulation, as metabolic optimization-microgravity (MO-MG), enhance tissue repair through targeted cellular integrated response. In the present study, WJ-MSCs were exposed for 24h to a simulated microgravity (µg) using a 3D random positioning machine (RPM). The 3D RPM provides a simulated microgravity of less than 10−3 g. Controls were placed in the static bar at 1 g to undergo the same vibration as the sample under µg conditions. At the end of 24h, cells were put in culture and exposed to REAC- MO-MG protocol for 6 days. The cycle consisted of 9 sessions, each lasting approximately 30 minutes. Sessions can be spaced out by a minimum of one hour and with no more than four sessions administered in a single day. We then evaluated cell morphology after REAC-MO-MG and analyzed gene expression of stemness-associated genes (Oct-4, Sox2 and Nanog), and some epigenetic factors, strictly related to stress response (Sirt1, DNMT1 and HSP70). We also evaluate stem cell potency by 21 days of differentiation in the presence of adipogenic or osteogenic conditioned medium. Our results clearly demonstrate a role of REAC MO-MG in restoring WJ-MSC potency, maintaining higher expression levels of the stemness markers and the epigenetic factors. Therefore, REAC- exposed cells are able to modulate stress response, counteracting apoptosis, as compared to WJ-MSCs exposed only to µg. These data demonstrate that MO-MG can act directly modulating cell response, restoring the altered expression of key genes involved in stemness and differentiation induced by microgravity, suggesting the potential use of this treatment in future space missions.
