Silk and collagen scaffolds for tendon reconstruction

Abstract

In this study, silk thread (Bombyx mori) was braided to a tube-like shape and sericin was removed from the silk tube. Thereafter, collagen/chondroitin-6-sulfate solution was poured into the silk tube, and the lyophilization process was performed. To assess the inflammatory response in vivo, raw silk and sericin-free silk tubes were implanted in the subcutaneous layer of mice. After 10 days of in vivo implantation, mild inflammatory responses were observed around the sericin-free silk tubes, and severe inflammation with the presence of neutrophils and macrophages was observed around the raw silk tubes. At 24 weeks post implantation, the regenerated tendon had a thick, cylindrical, grayish fibrous structure and a shiny white appearance, similar to that of the native tendon in the rabbit model of tendon defect. The average tensile strength of the native tendons was 220 ± 20 N, whereas the average tensile strength of the regenerated tendons was 167 ± 30 N and the diameter of the regenerated tendon (3 ± 0.2 mm) was similar to that of the native tendons (4 ± 0.3 mm). Histologically, the regenerated tendon resembled the native tendon, and all the regenerated tissues showed organized bundles of crimped fibers. Masson trichrome staining was performed for detecting collagen synthesis, and it showed that the artificial tendon was replaced by new collagen fibers and extracellular matrix. However, the regenerated tendon showed fibrosis to a certain degree. In conclusion, the artificial tendon, comprising a braided silk tube and lyophilized collagen sponge, was optimal for tendon reconstruction. Thus, this study showed an improved regeneration of neo-tendon tissues, which have the structure and tensile strength of the native tendon, with the use of the combination of collagen and silk scaffold.

Strategies to engineer tendon/ligament-to-bone interface: Biomaterials, cells and growth factors

“…Similarly, biomaterials for tendon/ligament tissue engineering include natural polymers (in particular collagen [48][49][50][51][52] and silk [46,[50][51][52]), synthetic polymers (such as PGA [53][54][55] and PLLA) [56,57] and decellularized native tendon/ligament matrices [58,59] (table 3). The pros and cons of each type of biomaterial are summarized in tables 2 and 3 for bone and tendon/ligament tissue engineering, respectively.…”

In vivo bioresponses to silk proteins

“…Thus, combining the mechanical benefits of silk with the cell compatibility benefits of collagen can make an ideal blend for many tissue engineering applications. Indeed, silk-collagen scaffolds greatly improved tendon reconstruction (27, 75, 76). Silk-collagen scaffolds had significantly increased regenerated tissue and organized collagen fibers compared to silk only scaffolds (75).…”

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

“…25,26 Recently, the fibroin fibers of the B. mori mulberry silkworm have been assessed for use in tendon/ ligament regeneration. 28,29,[35][36][37][38]60,61 These silk fibers have also been used as sutures since the late 19 th century 62 and when implanted subcutaneously, B. mori silk fibroin elicits very mild immune responses. 63,64 Indeed, the majority of silk based tissue engineered constructs utilize the fibroin from B. mori, most likely due to its high availability and good mechanical properties.…”

“…[32][33][34] Studies evaluating silk as a biomaterial for tendon regeneration have largely focused on the mulberry B. mori silk or composites of B. mori silk with either synthetic polymers or collagen. 28,29,[35][36][37][38] However, given that non-mulberry silks contain the cell binding RGD tripeptide motif, [39][40][41] and have been shown to support fibroblast-like and bone marrow-derived mesenchymal stem cell growth in vitro, 42,43 non-mulberry silk-derived scaffolds hold much promise as biomaterials for enhancing tendon tissue regeneration. 44 In this study, in vitro assays were used to assess the cytocompatibility and immunogenicity of a novel knitted, nonmulberry silk fibroin scaffold designed for use in tendon tissue regeneration.…”