Recombinant Silk Hydrogel as a Novel Dermal Filler Component: Preclinical Safety and Efficacy Studies of a New Class of Tissue Fillers

BACKGROUND: Hyaluronic acid-based tissue fillers are commonly used in reconstructive surgery as well as for aesthetic augmentation. A new type of recombinant silk-based tissue fillers might pose a beneficial alternative for surgeons and patients. OBJECTIVES: The aim of this study was to compare injectability, reshaping, tolerability, and post-implantation behavior of dermal filler preparations containing recombinant silk hydrogel with a commercially available hyaluronic acid filler in two different animal models. METHODS: Recombinant silk hydrogel as standalone preparation or as a mixture with commercial stabilized hyaluronic acid was tested in rodent and porcine animal models. The preparations were analyzed in detail and administered subdermally followed by clinical, volumetric, and histological monitoring of the subdermal depots over several months. RESULTS: Applicability, dosing and tissue distribution of the filler preparations were facilitated in the presence of silk hydrogel. No clinical complications attributable to tissue filler application were recorded. State of the art methods, such as high-performance magnetic resonance imaging, were applied successfully to monitor the volumetric development of the filler depots in live animals. CONCLUSIONS: The preclinical data demonstrates the basic suitability of recombinant silk hydrogel as safe and convenient tissue filler ingredient. Due to its shear thinning properties, recombinant silk hydrogel has the potential of a less painful application, a comfortable aesthetic reshaping immediately after administration, and negligible postoperative discomfort.