Silk Fibroin Hydroxyapatite Research Articles

The Performance of Cemented Femoral Prosthesis Based on New Gel Materials

In view of the problems in hip replacement, a new gel material is developed and incorporated into cemented femoral prosthesis. The material precipitates hydroxyapatite (HA) onto silk fibroin (SF) by biomimetic method, namely silk fibroin hydroxyapatite (SF–HA). Through X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis, HA precipitates on SF. Taking the gel time as the standard, 5 groups of gel materials are selected. Through in vitro degradation experiments, the degradation rate of these materials is 45%∼55%. Cell experiments (mouse L929 cells, osteoblasts HO-F) show that these cells have no cytotoxicity and support the growth of osteoblasts. In addition, in the vivo experiment (two groups), one group was treated with gelatin materials and the other group is treated with bone cement prosthesis transplantation directly. Comparing the indexes before and after operation, it proves that the new gel material has great application value in hip replacement surgery.

Functionalization of SF/HAP Scaffold with GO-PEI-miRNA inhibitor Complexes to Enhance Bone Regeneration through Activating Transcription Factor 4.

Evidence indicates that microRNAs (miRNAs) play vital roles in regulating osteogenic differentiation and bone formation.Methods: Here, we show that a polyethyleneimine (PEI)-functionalized graphene oxide (GO) complex efficiently loaded with the miR-214 inhibitor is assembled into silk fibroin/hydroxyapatite (SF/HAP) scaffolds that spatially control the release of the miR-214 inhibitor.Results: SF/HAP/GO scaffolds with nanosized GO show high mechanical strength, and their hierarchical microporous structures promote cell adhesion and growth. The SF/HAP/GO-PEI scaffolds loaded with mir-214 inhibitor (SF/HAP/GPM) were tested for their ability to enhance osteogenic differentiation by inhibiting the expression of miR-214 while inversely increasing the expression of activating transcription factor 4 (ATF4) and activating the Akt and ERK1/2 signaling pathways in mouse osteoblastic cells (MC3T3-E1) in vitro. Similarly, the scaffolds activated the osteoblastic activity of endogenous osteoblast cells to repair critical-sized bone defects in rats without the need for loading osteoblast cells.Conclusion: This technology is used to increase osteogenic differentiation and mineralized bone formation in bone defects, which helps to achieve cell-free scaffold-based miRNA-inhibitor therapy for bone tissue engineering.

Surface-modified silk hydrogel containing hydroxyapatite nanoparticle with hyaluronic acid–dopamine conjugate

Silk fibroin/hydroxyapatite (SF/HAp) composite hydrogels were fabricated in this study, having different HAp contents (0–33wt%) in SF matrix hydrogel. Surface modification of HAp nanoparticle with hyaluronic acid (HA)–dopamine (DA) conjugate improved a dispersibility of HAp in aqueous SF solution due to its negatively charged surface and therefore, fabrication of the SF composite hydrogel having HAp nanoparticles inside could be possible. Zeta potential of surface-modified HAP was examined by ELS. It demonstrates that surface of HAp was well modified to a negative charge with HA–DA. Morphological structure of SF hydrogel containing surface-modified HAp was examined by FE-SEM for analyzing pore structure of hydrogel and deposition of HAp nanoparticle in SF hydrogel. It was found that HAp nanoparticles were uniformly deposited on the pore wall of SF hydrogel. Structural characteristics of SF/HAp composite hydrogel was performed using X-ray diffraction and FT-IR analysis. It was found that β-sheet crystal conformation of SF was significantly influenced by the HAp content during gelation of a mixture of SF and HAp. As a result of MTT assay, the SF/HAp composite hydrogel showed excellent cell proliferation ability. Therefore, it is expected that SF hydrogel containing HAp nanoparticles has a high potential as bone regeneration scaffold.

Transplantation of human placenta-derived mesenchymal stem cells in a silk fibroin/hydroxyapatite scaffold improves bone repair in rabbits

The main requirements for successful tissue engineering of the bone are non-immunogenic cells with osteogenic potential and a porous biodegradable scaffold. The purpose of this study is to evaluate the potential of a silk fibroin/hydroxyapatite (SF/HA) porous material as a delivery vehicle for human placenta-derived mesenchymal stem cells (PMSCs) in a rabbit radius defect model. In this study, we randomly assigned 16 healthy adult New Zealand rabbits into two groups, subjected to transplantation with either SF/HA and PMSCs (experimental group) or SF/HA alone (control group). To evaluate fracture healing, we assessed the extent of graft absorption, the quantity of newly formed bone, and re-canalization of the cavitas medullaris using radiographic and histological tools. We performed flow cytometric analysis to characterize PMSCs, and found that while they express CD90, CD105 and CD73, they stain negative for HLA-DR and the hematopoietic cell surface markers CD34 and CD45. When PMSCs were exposed to osteogenic induction medium, they secreted calcium crystals that were identified by von Kossa staining. Furthermore, when seeded on the surface of SF/HA scaffold, they actively secreted extracellular matrix components. Here, we show, through radiographic and histological analyses, that fracture healing in the experimental group is significantly improved over the control group. This strongly suggests that transplantation of human PMSCs grown in an SF/HA scaffold into injured radius segmental bone in rabbits, can markedly enhance tissue repair. Our finding provides evidence supporting the utility of human placenta as a potential source of stem cells for bone tissue engineering.

Osteogenic differentiation of bone marrow mesenchymal stem cells on the collagen/silk fibroin bi‐template‐induced biomimetic bone substitutes

Biomimetic bone substitutes of collagen-silk fibroin/hydroxyapatite (COL-SF/HA) were synthesized via a bi-template-induced coassembly strategy. Collagen-hydroxyapatite (COL-HA) and silk fibroin-hydroxyapatite (SF-HA) served as controls were prepared with similar method. The osteogenic differentiation ability of bone marrow mesenchymal stem cells (BMSCs) seeded onto the resulting materials was evaluated both in vitro and in vivo. The results suggested that the bi-template-induced biomimetic substitutes were able to support the growth and proliferation of BMSCs. We further demonstrated that BMSCs were stimulated to differentiate into the osteoblast cell lineage by evaluating several specific osteogenic markers including staining of alkaline phosphate (ALP) and calcium nodular and expression of osteogenic genes of osteocalcin (OCN) and osteonectin (ONN). The rat femoral defect model was used to assess the aforementioned biomimetic bone substitutes combined with BMSCs in vivo. Histological analysis indicated that the bi-template material exhibited good biocompatibility and strong ability of the new bone formation in comparison with the control of single-template material in vivo.

Repairing radial segmental bone defects with tissue engineered bone of silk fibroin/hydroxyapatite in rabbits

Objective To explore the bone formation of silk fibroin/hydroxyapatite (SF/HA)co-cultured with bone marrow stromal cells (BMSCs) in rabbits. Methods The purified, culture-expanded and osteogenic BMSCs were combined with SF/HA in vitro to construct a tissue engineered bone. A segmental bone defect (15 mm in length) was created at each left radius in the rabbits which were randomized into 3 groups. The tissue engineered bone was implanted through open operation into the bone defects in Group 1. Group 2 was implanted with SF/HA scaffold alone, and Group 3 without any implant (unfilled). Bone formation and moulding were observed by X-ray at 4, 8, 12 and 16 weeks and by spiral CT reconstruction at 16 weeks. Results The rate and quality of new bone formation were significantly different among Group 1, Group 2 and Group 3 by radiography and histological scores ( P ＜ 0. 05). The segmental bone defects were completely united in Group 1, but partially united in Group 2. There was no new bone formation and the defects were only repaired by fibrous tissue in Group 3. Conclusion SF/HA with BMSCs has a good ability of repairing segmental bone defects. Key words: Silk; Hydroxyapatites; Tissue engineering; Bone defect; Rabbits

The use of silk fibroin/hydroxyapatite composite co-cultured with rabbit bone-marrow stromal cells in the healing of a segmental bone defect

In a rabbit model we investigated the efficacy of a silk fibroin/hydroxyapatite (SF/HA) composite on the repair of a segmental bone defect. Four types of porous SF/HA composites (SF/HA-1, SF/HA-2, SF/HA-3, SF/HA-4) with different material ratios, pore sizes, porosity and additives were implanted subcutaneously into Sprague-Dawley rats to observe biodegradation. SF/HA-3, which had characteristics more suitable for a bone substitute based on strength and resorption was selected as a scaffold and co-cultured with rabbit bone-marrow stromal cells (BMSCs). A segmental bone defect was created in the rabbit radius. The animals were randomised into group 1 (SF/HA-3 combined with BMSCs implanted into the bone defect), group 2 (SF/HA implanted alone) and group 3 (nothing implanted). They were killed at four, eight and 12 weeks for visual, radiological and histological study. The bone defects had complete union for group 1 and partial union in group 2, 12 weeks after operation. There was no formation of new bone in group 3. We conclude that SF/HA-3 combined with BMSCs supports bone healing and offers potential as a bone-graft substitute.

Preparation and Characteristics of Gradient Silk Fibroin/Hydroxyapatite Porous Composites

The gradient silk fibroin (SF)/ hydroxyapatite (HA) porous composite used for the scaffold of cartilage-bone tissue regeneration was prepared with SF powder and HA powder by layer-by-layer mould pressing method and granular NaCl as porogent. The characteristics were performed by Electron Microprobe and Energy Dispersive Spectometer (EDS). It indicated that the distribution of SF and HA presented linear gradient along the thickness direction in the materials. The porosity of composites increased with NaCl content increasing, while the density decreased. As the result of mechanical properties measurement, the bending strength and compressive strength decreased with NaCl content increasing. Compared the mechanical properties between gradient material and non-gradient material, it indicated that bending strength of gradient SF/HA porous material was higher than non-gradient SF/HA porous material’s.