Transformation of SH-SY5Y cell line into neuron-like cells: Investigation of electrophysiological and biomechanical changes.

SH-SY5Y human neuroblastoma cells are commonly used as neuronal models. Here, we examined different aspects of SH-SY5Y cell differentiation. Various differentiation protocols have been proposed previously, including treatments with retinoic acid, brain-derived neurotrophic factor (BDNF), cholesterol and oestradiol. We examined undifferentiated SH-SY5Y cells (UNDIFF); cells differentiated by the treatment with retinoic acid (RA); retinoic acid + BDNF (RB); and retinoic acid + BDNF + cholesterol + oestradiol (RBCE). We performed whole-cell patch-clamp recordings from these cells and nanomechanically characterised them by using atomic force microscopy (AFM). Our results indicated that Na currents become most pronounced in the differentiated RB cells, whereas UNDIFF SH-SY5Y cells had significantly larger K currents, which is a characteristic feature of cancer cells. AFM observations of these two groups showed that Young's moduli of SH-SY5Y cells increased threefold with differentiation. Furthermore, we showed a direct relationship between Na channel activity and elasticity in these cells. We conclude that SH-SY5Y human neuroblastoma cells should be used as a neuronal model only when they are differentiated by the treatment with retinoic acid and BDNF.