Degree of differentiation impacts neurobiological signature and resistance to hypoxia of SH-SY5Y cells

SH-SY5Y cells are valuable neuronal models for studying patho-mechanisms and treatment targets in brain disorders due to their easy maintenance, rapid expansion, and low costs. However, the use of various degrees of differentiation hampers appreciation of results and may limit the translation of findings to neurons or the brain. Here, we studied the neurobiological signatures of SH-SY5Y cells in terms of morphology, expression of neuronal markers, and functionality at various degrees of differentiation, as well as their resistance to hypoxia. We compared these to neurons derived from human induced pluripotent stem cells (hiPSCs), a well-characterized neuronal model. We cultured SH-SY5Y cells and neurons derived from hiPSCs on glass coverslips or micro-electrode arrays. We studied expression of mature neuronal markers, electrophysiological activity, and sensitivity to hypoxia at various degrees of differentiation (one day up to three weeks) in SH-SY5Y cells. We used hiPSC derived neurons as a reference. Undifferentiated and shortly differentiated SH-SY5Y cells lacked neuronal characteristics. Expression of neuronal markers and formation of synaptic puncta increased during differentiation. Longer differentiation was associated with lower resistance to hypoxia. At three weeks of differentiation, MAP2 expression and vulnerability to hypoxia were similar to hiPSC-derived neurons, while the number of synaptic puncta and detected events were significantly lower. Our results show that at least three weeks of differentiation are necessary to obtain neurobiological signatures that are comparable to those of hiPSC-derived neurons, as well as similar sensitivities to metabolic stress This indicates that extended differentiation protocols should be used to study neuronal characteristics and to model brain disorders with SH-SY5Y cells. We provided insights that may offer the basis for the utilization of SH-SY5Y cells as a more relevant neuronal model in the study of brain disorders.