^{Fabrication and Characterization of Biphasic Silk Fibroin Scaffolds for Tendon/Ligament-to-Bone Tissue Engineering}

Abstract

Tissue engineering is an attractive strategy for tendon/ligament-to-bone interface repair. The structure and extracellular matrix composition of the interface are complex and allow for a gradual mechanical stress transfer between tendons/ligaments and bone. Thus, scaffolds mimicking the structural features of the native interface may be able to better support functional tissue regeneration. In this study, we fabricated biphasic silk fibroin scaffolds designed to mimic the gradient in collagen molecule alignment present at the interface. The scaffolds had two different pore alignments: anisotropic at the tendon/ligament side and isotropic at the bone side. Total porosity ranged from 50% to 80% and the majority of pores (80-90%) were <100-300 μm. Young's modulus varied from 689 to 1322 kPa depending on the type of construct. In addition, human adipose-derived mesenchymal stem cells were cultured on the scaffolds to evaluate the effect of pore morphology on cell proliferation and gene expression. Biphasic scaffolds supported cell attachment and influenced cytoskeleton organization depending on pore alignment. In addition, the gene expression of tendon/ligament, enthesis, and cartilage markers significantly changed depending on pore alignment in each region of the scaffolds. In conclusion, the biphasic scaffolds fabricated in this study show promising features for tendon/ligament-to-bone tissue engineering.

Water‐insoluble amorphous silk fibroin scaffolds from aqueous solutions

“…Regenerated silk fibroin (RSF), derived from the silkworm cocoon, is a useful biomaterial as a cell‐support matrix for osteoblasts, endothelial cells, nerve cells and various stem cells, as a scaffold for bone, cartilage, muscle, blood vessels, skin and nerves, and as a carrier for hydrophilic and hydrophobic drugs and growth factors (Chen, Chen, Kuo, Li, & Chen, ; Crivelli et al, ; Farè et al, ; Font Tellado et al, ; Font Tellado et al, ; Hennecke et al, ; Jo et al, ; Kundu, Rajkhowa, Kundu, & Wang, ; Le, Liaudanskaya, Bonani, Migliaresi, & Motta, ; Moses, Nandi, & Mandal, ; Musson et al, ; Sell, McClure, Ayres, Simpson, & Bowlin, ; Teuschl et al, ; Woloszyk, Buschmann, Waschkies, Stadlinger, & Mitsiadis, ; Y. P. Zhang et al, ). Besides the inherent virtues of silk fibroin, such as biocompatibility, a green formation process, and tunable biodegradability, another feature is its diversity of conformations, hierarchical microstructures and various material states, endowing the possibility of designing biomaterials with selective and useful performance (Gorenkova et al, ; Hu et al, ; Kumar, Nandi, Kaplan, & Mandal, ; Qi et al, ; Rockwood et al, ).…”

Next generation tissue engineering of orthopedic soft tissue-to-bone interfaces

“…6A). [57] The processing conditions were designed to form a continuous scaffold with a porous, trabecular bone-like structure that transitions into a fiber-like morphology. The porous region results from salt-leaching, in which a solution of silk fibroin and NaCl is frozen and freeze-dried.…”

“…These processing methods result in a continuous silk structure that mimics the morphology of collagen in the native enthesis. [57] Similar scaffolds have been produced for the osteochondral interface, demonstrating the customizability of these techniques. [66] …”

“…6A). [57] These examples emphasize the importance of scaffold material and biochemical design in order to inform cell behavior when generating enthesis constructs.…”

“…Reprinted with permission from TISSUE ENGINEERING, Part A, Volume 23, Issue 15-16, published by Mary Ann Liebert, Inc., New Rochelle, NY. [57] (B) Bone-ligament-bone ACL replacement generated using stem cell self-assembly and targeted differentiation. Images from left-to-right: full tissue engineered construct, immunostained for collagen (red) and DAPI stained (nuclear stain) section showing bony region prior to implantation, immunostained for collagen (red) and DAPI stained (nuclear stain) section showing ligament region prior to implantation, image of regenerated fibrocartaliginous region with aligned nuclei (arrow) after 2 months implantation.…”