Spider Silk Coatings as a Bioshield to Reduce Periprosthetic Fibrous Capsule Formation

Medical grade silicones have been employed for decades in medical applications. The associated long-term complications, such as capsule formation and contraction have, however, not been fully addressed yet. The aim of this study is to elucidate if capsule formation and/or contraction can be mitigated by veiling the surface of the silicone during the critical phase after implantation. Medical grade silicone implants are homogeneously coated with a micrometer thin layer of recombinant spider silk proteins. Biocompatibility analysis in vitro and in vivo focuses on specific physiological reactions. Applying quantitative methods for the determination of marker-specific gene expression and protein concentration, it is detected that the silk coating inhibits fibroblast proliferation, collagen I synthesis, and differentiation of monocytes into CD68-positive histiocytes. It significantly reduces capsule thickness, post-operative inflammation, synthesis and re-modeling of extracellular matrix, and expression of contracture-mediating factors. Therefore, coatings made of recombinant spider silk proteins considerably reduce major post-operative complications associated with implantation of silicone-based alloprosthetics, such as capsular fibrosis and contraction, rendering spider silk coatings a bioshield for such implants.