Cellule staminali neuronali e microglia: cross - talk in modello in vitro di neuroinfiammazione

Inhibition of microglia-mediated neuroinflammation is an important terapeuthic target in order to avoid cognitive and motor impairment in brain ischemia . Reportedly, neural stem cell (NSC) brain grafts have neuroprotective effecs 1. It has been proposed that these positive effects are not caused only by NSC proliferation and generation of new neurons, but also by a modulation of the brain lesion environment 2. Our primary aim was to ascertain whether NSC were capable of modifying microglial activation in vitro. We used ATP as inflammatory stimuli, since it is massively released from damaged neurons and is responsible of activation of microglia during ischemia3. We demonstrated that N9 murine microglia cells incubated with conditioned media (CM) from NSC culture have a blunted response to ATP. In fact, ATP stimulation of N9 cells preincubated with CM at different passages induced a reduced release of intracellular calcium compared to controls (Fig.1). Moreover, CM preincubation significantly inhibited the expression of inflammatory cytokines like TNF-alfa, COX-2, and IL-10 that are up-regulated after ATP stimulation (Fig.2) Reportedly, high-dose ATP (>1mM) exposure is detrimental both for neurons and microglial cells4. We tested CM action of survival of N9 microglia treated with 3mM ATP for 24 hours. CM preincubation for 24 hours was capable of significantly reducing N9 mortality induced by ATP treatment (Fig.3). In conclusion NSC release soluble factors that have an antinfiammatory action blunting N9 response to ATP stimulation.