Silk-Based Materials for Hard Tissue Engineering

Abstract

Hard tissues, e.g., bone, are mechanically stiff and, most typically, mineralized. To design scaffolds for hard tissue regeneration, mechanical, physico-chemical and biological cues must align with those found in the natural tissue. Combining these aspects poses challenges for material and construct design. Silk-based materials are promising for bone tissue regeneration as they fulfill several of such necessary requirements, and they are non-toxic and biodegradable. They can be processed into a variety of morphologies such as hydrogels, particles and fibers and can be mineralized. Therefore, silk-based materials are versatile candidates for biomedical applications in the field of hard tissue engineering. This review summarizes silk-based approaches for mineralized tissue replacements, and how to find the balance between sufficient material stiffness upon mineralization and cell survival upon attachment as well as nutrient supply.

Ultrasound regulated flexible protein materials: Fabrication, structure and physical-biological properties

“…Natural silk, which is highly available due to its use in the textile industry, has become a widely studied protein material in the biomedical and bioengineering field. As a renewable resource available in large quantities, silk is also nontoxic and highly biocompatible [1] , [2] , [3] , [4] , [5] , [6] . Natural silk fibers are comprised of silk fibroin protein fibers with a glycoprotein coating.…”

Composites Based on Hydroxyapatite and Whey Protein Isolate for Applications in Bone Regeneration

“…Due to their structural similarity to the natural extracellular matrix (ECM), they show a promising ability to encapsulate drugs, cells or bioactive particles. Thus, they function as carriers of active substances which can facilitate local controlled release [ 19 , 20 , 21 ]. Hydrogels are characterized by high absorbency, tunable viscoelasticity, and permeability to oxygen and essential nutrients.…”

The innate immune response of self-assembling silk fibroin hydrogels

“…For example, silk fibroin hydrogels are particularly promising because these materials can serve both as an extracellular matrix mimetic 5 or as a release reservoir for therapeutic payloads 6,7 . Proposed applications include, but are not limited to, anticancer drug delivery 6,8 , pancreatic islet transplantation 9,10 , soft 11,12 and hard tissue 13 engineering and tissue fillers (Silk Medical Aesthetics, Inc. Medford, MA, USA; ClinicalTrials.gov Identifier NCT04085822). The Food and Drug Administration (USA) recently approved the first silk fibroin hydrogel product (Silk Voice, Sofregen Inc, Medford, MA, USA) for use in humans in the treatment of vocal fold medialisation and vocal fold insufficiency.…”

“…6,21 ). Silk fibroin hydrogels are also used for hard tissue engineering applications (reviewed in 13 ). For example, silk fibroin hydrogels outperformed polylactide-co-glycolide controls in a critical bone defect animal model without inducing an overt tissue response 22 .…”