In VitroEvaluation of a Novel Non-Mulberry Silk Scaffold for Use in Tendon Regeneration

Abstract

Tearing of the rotator cuff tendon in the shoulder is a significant clinical problem, with large/full-thickness tears present in *22% of the general population and recurrent tear rates postarthroscopic repair being quoted as high as 94%. Tissue-engineered biomaterials are increasingly being investigated as a means to augment rotator cuff repairs, with the aim of inducing host cell responses to increase tendon tissue regeneration. Silk-derived materials are of particular interest due to the high availability, mechanical strength, and biocompatibility of silks. In this study, Spidrex Ò , a novel knitted, non-mulberry silk fibroin scaffold was evaluated in vitro for its potential to improve tendon regeneration. Spidrex was compared with a knitted Bombyx mori silk scaffold, a 3D collagen gel and Fiberwire Ò suture material. Primary human and rat tenocytes successfully adhered to Spidrex and significantly increased in number over a 14 day period ( p < 0.05), as demonstrated by fluorescent calcein-AM staining and alamarBlue Ò assays. A similar growth pattern was observed with human tenocytes cultured on the B. mori scaffold. Morphologically, human tenocytes elongated along the silk fibers of Spidrex, assuming a tenocytic cell shape, and were less circular with a higher aspect ratio compared with human tenocytes cultured on the B. mori silk scaffold and within the collagen gel ( p < 0.05). Gene expression analysis by real-time PCR showed that rat tenocytes cultured on Spidrex had increased expression of tenocyte-related genes such as fibromodullin, scleraxis, and tenomodulin ( p < 0.05). Expression of genes that indicate transdifferentiation toward a chondrocytic or osteoblastic lineage were significantly lower in tenocytes cultured on Spidrex in comparison to the collagen gel ( p < 0.05). Immunogenicity assessment by the maturation of and cytokine release from primary human dendritic cells demonstrated that Spidrex enhanced dendritic cell maturation in a similar manner to the clinically used suture material Fiberwire, and significantly upregulated the release of proinflammatory cytokines ( p < 0.05). This suggests that Spidrex may induce an early immune response postimplantation. While further work is required to determine what effect this immune response has on the tendon healing process, our in vitro data suggests that Spidrex may have the cytocompatibility and bioactivity required to support tendon regeneration in vivo.

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, ).…”

Tissue engineering of human knee meniscus using functionalized and reinforced silk‐polyvinyl alcohol composite three‐dimensional scaffolds: Understanding the in vitro and in vivo behavior

“…The native human medial meniscus showed 8 kPa compressive strength at 12% strain, whereas, the compressive strengths of the scaffolds were in the range of 30–115 kPa at that strain level. ESM is a complex biopolymer with collagen fibers and ceramic particles, whose property is similar to the other cellular solids at higher strain . The autoclaved, lyophilized and powdered ESM imparts structural stability in the SF‐PVA matrix which was responsible for enhanced mechanical property.…”

“…ESM is a complex biopolymer with collagen fibers and ceramic particles, whose property is similar to the other cellular solids at higher strain. 29,30 The autoclaved, lyophilized and powdered ESM imparts structural stability in the SF-PVA matrix which was responsible for enhanced mechanical property. The compressive moduli reported for stacked SF scaffolds were ranging from 164 to 347 kPa.…”

Current Status of Tissue-engineered Scaffolds for Rotator Cuff Repair

“…Proteins such as collagen, hyaluronic acid, and silk 34 have also been used to fabricate scaffolds but typically have inferior mechanical properties compared to synthetic polymers. More complex extracellular matrices such as tendon-derived matrix have also been investigated for rotator cuff tissue engineering, either by coating onto the surface of polymer fibers, 35 or by incorporating the matrix directly into the polymer fiber.…”