High-strength silk protein scaffolds for bone repair

TLDR

Biomaterials for bone tissue regeneration are a major focus of orthopedic research, yet few polymeric options are used today because they fail to provide sufficient compressive strength for load‑bearing grafts. This study aims to develop a high‑compressive‑strength (~13 MPa hydrated) polymeric bone composite based on silk protein–protein interfacial bonding. Micron‑sized silk fibers (10–600 µm) were incorporated as reinforcement in a compact fiber composite, enabling tunable compressive strength, surface roughness, and porosity by varying fiber length. The composite promoted osteogenic differentiation of human bone marrow‑derived mesenchymal stem cells in vitro and elicited minimal in vivo immunomodulatory responses, indicating compatibility for bone engineering applications.

Abstract

Biomaterials for bone tissue regeneration represent a major focus of orthopedic research. However, only a handful of polymeric biomaterials are utilized today because of their failure to address critical issues like compressive strength for load-bearing bone grafts. In this study development of a high compressive strength (~13 MPa hydrated state) polymeric bone composite materials is reported, based on silk protein-protein interfacial bonding. Micron-sized silk fibers (10-600 µm) obtained utilizing alkali hydrolysis were used as reinforcement in a compact fiber composite with tunable compressive strength, surface roughness, and porosity based on the fiber length included. A combination of surface roughness, porosity, and scaffold stiffness favored human bone marrow-derived mesenchymal stem cell differentiation toward bone-like tissue in vitro based on biochemical and gene expression for bone markers. Further, minimal in vivo immunomodulatory responses suggested compatibility of the fabricated silk-fiber-reinforced composite matrices for bone engineering applications.