Abstract
Medical implants offer a unique and powerful therapeutic approach in many areas of medicine. However, their lifetime is often limited as they may cause a foreign body reaction (FBR) leading to their encapsulation by scar tissue1–4. Despite the importance of this process, how cells recognise implanted materials is still poorly understood5, 6. Here, we show how the mechanical mismatch between implants and host tissue leads to FBR. Fibroblasts and macrophages, which are both crucially involved in mediating FBR, became activated when cultured on materials just above the stiffness found in healthy tissue. Coating implants with a thin layer of hydrogel or silicone with a tissue-like elastic modulus of ∼1 kPa or below led to significantly reduced levels of inflammation and fibrosis after chronic implantation both in peripheral nerves and subcutaneously. This effect was linked to the nuclear localisation of the mechanosensitive transcriptional regulator YAP in vivo. Hence, we identify the mechanical mismatch between implant and tissue as a driver of FBR. Soft implant coatings matching the mechanical properties of host tissue minimized FBR and may be used as a novel therapeutic strategy to improve long-term biomedical implant stability without extensive modification of current implant manufacturing techniques, thus facilitating clinical translation.
One sentence summary Foreign body reaction to medical implants can be avoided by matching the stiffness of the implant surface to that of the host tissue.
