ИСТИНА

Sympathetic neurons are important component of mesenchymal stem cells (MSC) niche and noradrenaline regulates biological activities of these cells. Here we examined the mechanisms of regulation of MSC responsiveness to noradrenaline. Using flow cytometry, we demonstrated that MSC express all examined isoforms of adrenoreceptors, whereas α1A isoform was the most abundant in adipose tissue-derived MSCs. Using calcium imaging in single cells, we demonstrated that only 6.9 ±0.8% of MSCs responded to noradrenaline by intracellular calcium release. Noradrenaline increased MSC sensitivity to catecholamines in a transitory mode. Within 6 hrs after incubation with noradrenaline the proportion of cells responding by Ca2+ release to the fresh noradrenaline addition has doubled but declined to the baseline after 24 hrs. Increased sensitivity was due to the elevated quantities of α1A adrenoreceptors on MSCs. Such elevation depended on the stimulation of β-adrenoreceptors and adenylate cyclase activation. These data for a first time clarify mechanisms of regulation of MSC sensitivity to noradrenaline.