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

Abstract

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.

Natural Ingredients in Functional Coatings—Recent Advances and Future Challenges

“…When active substances (synthetic pharmaceutics or natural compounds) cannot be used alone, composite materials based on different polymers can be developed for enhancing their properties. Due to their effective biocompatibility and biodegradability, natural polymers used for coatings in medical devices, such as chitosan, starch, alginate, collagen, gelatin, or silk, were reported by different authors [45][46][47]. Moreover, different studies revealed that the construction of such medical devices in the form of a layer-by-layer coating can generate multi-component coatings with an increased ability to regulate the release of active substances [48][49][50].…”

Special Issue on Surfaces Modification and Analysis for Innovative Biomaterials

“…Wöltje and coworkers explored the genetic alteration of silkworms to obtain silk fibers functionalized with human platelet-derived growth factors [4]. The fibers were also modified with bioceramics and assembled into a 3D textile implant to achieve high levels of osteoconductivity.…”

Toughening of Bioceramic Composites for Bone Regeneration

“…In the last century, an intense research effort has been devoted to the reinforcement of bioceramics for different applications. In this respect, various approaches have been proposed, including modified sintering treatments [51][52][53], combination with polymeric phases to produce composites [49,54,55], the addition of fibers or the development of additive manufacturing as a 3D technique to prepare complex-shaped bioceramic structures [34,[56][57][58][59][60]. A major approach to this purpose is the addition of ceramic particles, whiskers, and fibers to the ceramic matrix to improve the fracture toughness [61][62][63][64][65].…”