Oxygen matters: Unraveling the role of oxygen in the neuronal response to cisplatin

Cell culture is a fundamental experimental tool for understanding cell physiology. However, translating these findings to in vivo settings has proven challenging. Replicating donor tissue conditions, including oxygen levels, is crucial for achieving meaningful results. Nevertheless, oxygen culture conditions are often overlooked, particularly in the context of chemotherapy-induced neurotoxicity. In this study we want to investigate the role of oxygen levels in primary neuronal cultures by comparing neuron performance under cisplatin exposure (1 µg/ml) in normoxia (representing atmospheric conditions in a standard incubator; 18.5% O2) and physioxia (representing physiologic oxygen conditions in nervous tissue; 5% O2). Four experiments were conducted to assess survival, neurite development, senescence markers, and pro-inflammatory cytokine secretion. Under control conditions, both atmospheric experimental paradigms exhibited similar behavior. In contrast, after cisplatin administration, sensory neurons cultured in normoxia suffer more death, showed an evolutionarily pro-inflammatory cytokine profile (higher expression of IL-6, CCL5, CCL3, and CCL11) over time, and activated apoptotic-regulated neuron death markers, as evidenced by caspase-3 activation. In contrast, in physioxia conditions, neurons submitted to cisplatin revealed senescence markers (up-regulation of p21, p16, and down-regulation of LAMß1) and an attenuated inflammatory secretome. These results underscore the critical role of oxygen in neuronal cultures, particularly in studying compounds where neuronal damage is mechanistically linked to oxidative stress. Even at identical doses of evaluated neurotoxic drugs, distinct cellular outcomes and phenotypic fates can emerge, impacting translatability to in vivo models.