Cytocompatibility Study of Stainless Steel 316l Against Differentiated SH-SY5Y Cells

Stainless steel (SS) 316l constitutes a popular biomaterial with various applications as implants in cardiovascular and orthopedic surgery, as well as in dentistry. Nevertheless, its cytocompatibility against neuronal cells has not been investigated, a feature that is important for the construction of implants that require contact with neurons, e.g., neuronal electrodes. In addition, most cytocompatibility studies have focused on decorated or surface-modified SS 316l. On the other hand, SH-SY5Y cells are an established cellular model for cytocompatibility studies of potential biomaterials given their ability to differentiate into neuron-like cells. Here, we used retinoic-acid-differentiated SH-SY5Y cells and SH-SY5Y controls to investigate the cytocompatibility and biomimetics of uncoated SS 316l. The assessment of cytocompatibility was based on the determination of differentiation markers by immunofluorescence, RT-qPCR, and the neurite growth of these cells attached on SS 316l and standard tissue culture polystyrene (TCP) surfaces. Even though the neurite length was shorter in differentiated SH-SY5Y cells grown on SS 316l, no other significant changes were found. In conclusion, our results suggest that the uncoated SS 316l mimics a natural bio-surface and allows the adhesion, growth, and differentiation of SH-SY5Y cells. Therefore, this alloy can be directly applied in the emerging field of biomimetics, especially for the development of implants or devices that contact neurons.