Functionalization of Silk Fibers by PDGF and Bioceramics for Bone Tissue Regeneration

Bone regeneration is a complex, well-organized physiological process of bone formation observed during normal fracture healing and involved in continuous remodeling throughout adult life. An ideal medical device for bone regeneration requires interconnected pores within the device to allow for penetration of blood vessels and cells, enabling material biodegradation and bone ingrowth. Additional mandatory characteristics include an excellent resorption rate, a 3D structure similar to natural bone, biocompatibility, and customizability to multiple patient-specific geometries combined with adequate mechanical strength. Therefore, endless silk fibers were spun from native silk solution isolated from silkworm larvae and functionalized with osteoconductive bioceramic materials. In addition, transgenic silkworms were generated to functionalize silk proteins with human platelet-derived growth factor (hPDGF). Both, PDGF-silk and bioceramic modified silk were then assembled into 3D textile implants using an additive manufacturing approach. Textile implants were characterized in terms of porosity, compressive strength, and cyclic load. In addition, osteogenic differentiation of mesenchymal stem cells was evaluated. Silk fiber-based 3D textile implants showed good cytocompatibility and stem cells cultured on bioceramic material functionalized silk implants were differentiating into bone cells. Thus, functionalized 3D interconnected porous textile scaffolds were shown to be promising biomaterials for bone regeneration.