The surface topography of silicone breast implants mediates the foreign body response in mice, rabbits and humans

Silicone is widely used in chronic implants and is generally perceived to be safe. However, textured breast implants have been associated with immune-related complications, including malignancies. Here, by examining for up to one year the foreign body response and capsular fibrosis triggered by miniaturized or full-scale clinically approved breast implants with different surface topography (average roughness, 0-90 μm) placed in the mammary fat pads of mice or rabbits, respectively, we show that surface topography mediates immune responses to the implants. We also show that the surface surrounding human breast implants collected during revision surgeries also differentially alters the individual's immune responses to the implant. Moreover, miniaturized implants with an average roughness of 4 μm can largely suppress the foreign body response and fibrosis (but not in T-cell-deficient mice), and that tissue surrounding these implants displayed higher levels of immunosuppressive FOXP3⁺ regulatory T cells. Our findings suggest that, amongst the topographies investigated, implants with an average roughness of 4 μm provoke the least amount of inflammation and foreign body response.