Synthesis of the New-Type Vascular Endothelial Growth Factor-Silk Fibroin-Chitosan Three-Dimensional Scaffolds for Bone Tissue Engineering and In Vitro Evaluation.

The objective of the study was to discuss the biocompatibility of the vascular endothelial growth factor-silk fibroin-chitosan (VEGF-SF-CS) scaffolds. To offer an ideal scaffold for bone tissue engineering, the author added vascular endothelial growth factor (VEGF) into silk fibroin-chitosan (SF-CS) scaffold directly to reconstruct a three-dimensional scaffold for the first time, SF-CS scaffold was loaded with VEGF and evaluated as a growth factor-delivery device. Human fetal osteoblast cell was seeded on the VEGF-SF-CS scaffolds and SF-CS scaffolds. On VEGF-SF-CS and SF-CS scaffolds, the cell adhesion rate was increased as time went on. Scanning electron microscopy: the cells grew actively and had normal multiple fissions, granular and filamentous substrates could be seen around the cells, and cell microfilaments were closely connected with the scaffolds. The cells could not only show the attached growth on surfaces of the scaffolds, but also extend into the scaffolds. Cell Counting Kit-8 and alkaline phosphatase analysis proved that the VEGF could significantly promote human fetal osteoblast1.19 cells growth and proliferation in the SF-CS scaffolds, but the enhancement of osteoblasts cell proliferation and activity by VEGF was dependent on time.

Study on Exosomes Promoting the Osteogenic Differentiation of ADSCs in Graphene Porous Titanium Alloy Scaffolds.

Titanium and titanium alloys (Ti6Al4V and Ti) have been widely used in bone tissue engineering to repair maxillofacial bone defects caused by traumas and tumors. However, such materials are also bio-inert, which does not match the elastic modulus of bone. Therefore, different surface modifications have been proposed for clinical application. Based on the use of traditional titanium alloy in the field of bone repair defects, we prepared a compound Gr-Ti scaffold with ADSC-derived Exos. The results showed that Gr-Ti scaffolds have low toxicity and good biocompatibility, which can promote the adhesion and osteogenic differentiation of ADSCs. Exos played a role in promoting osteogenic differentiation of ADSCs: the mRNA levels of RUNX2, ALP, and Osterix in the Gr-Ti/Exos group were significantly higher than those in the Gr-Ti group, which process related to the Wnt signaling pathway. Gr-Ti scaffolds with ADSCs and ADSC-derived Exos successfully repaired rabbit mandibular defects. The bone mineral density and the bending strength of the Gr-Ti/Exos group was significantly higher than that of the Gr-Ti group. This study provides a theoretical basis for the research and development of new clinical bone repair materials.

In vitro evaluation of a bone morphogenetic protein­2 nanometer hydroxyapatite collagen scaffold for bone regeneration.

Scaffold fabrication and biocompatibility are crucial for successful bone tissue engineering. Nanometer hydroxyapatite (nHAP) combined with collagen (COL) is frequently utilized as a suitable osseous scaffold material. Furthermore, growth factors, including bone morphogenetic protein­2 (BMP­2), are used to enhance the scaffold properties. The present study used blending and freeze­drying methods to develop a BMP­2­nHAP­COL scaffold. An ELISA was performed to determine the BMP­2 release rate from the scaffold. Flow cytometry was used to identify rat bone marrow­derived mesenchymal stem cells (BMSCs) prior to their combination with the scaffold. Scanning electron microscopy was used to observe the scaffold structure and BMSC morphology following seeding onto the scaffold. BMSCs were also used to assess the biological compatibility of the scaffold in vitro. BMP­2­nHAP­COL and nHAP­COL scaffolds were assessed alongside the appropriate control groups. Cells were counted to determine early cell adhesion. Cell Counting kit­8 and alkaline phosphatase assays were used to detect cell proliferation and differentiation, respectively. Gross morphology confirmed that the BMP­2­nHAP­COL scaffold microstructure conformed to the optimal characteristics of a bone tissue engineering scaffold. Furthermore, the BMP­2­nHAP­COL scaffold exhibited no biological toxicity and was demonstrated to promote BMSC adhesion, proliferation and differentiation. The BMP­2­nHAP­COL scaffold had good biocompatibility in vitro, and may therefore be modified further to construct an optimized scaffold for future bone tissue engineering.

Synthesis of and in vitro and in vivo evaluation of a novel TGF-ß1-SF-CS three-dimensional scaffold for bone tissue engineering.

The role of transforming growth factor-ß1 (TGF-ß1) in normal human fracture healing has been previously demonstrated. The objective of the present study was to examine the biocompatibility of TGF-ß1-silk fibroin-chitosan (TGF-ß1-SF-CS) three-dimensional (3D) scaffolds in order to construct an ideal scaffold for bone tissue engineering. We added TGF-ß1 directly to the SF-CS scaffold to construct a 3D scaffold for the first time, to the best of our knowledge, and performed evaluations to determine whether it may have potential applications as a growth factor delivery device. Bone marrow-derived mesenchymal stem cells (BMSCs) were seeded on the TGF-ß1-SF-CS scaffolds and the silk fibroin-chitosan (SF-CS) scaffolds. On the TGF-ß1­SF-CS and the SF-CS scaffolds, the cell adhesion rate increased in a time­dependent manner. Using a Cell Counting Kit-8 (CCK-8) assay and analyzing the alkaline phosphatase (ALP) expression proved that TGF-ß1 significantly enhanced the growth and proliferation of BMSCs on the SF-CS scaffolds in a time-dependent manner. To examine the in vivo biocompatibility and osteogenesis of the TGF-ß1­SF-CS scaffolds, the TGF-ß1-SF-CS scaffolds and the SF-CS scaffolds were implanted in rabbit mandibles and studied histologically and microradiographically. The 3D computed tomography (CT) scan and histological examinations of the samples showed that the TGF-ß1-SF-CS scaffolds exhibited good biocompatibility and extensive osteoconductivity with the host bone after 8 weeks. Moreover, the introduction of TGF-ß1 to the SF-CS scaffolds markedly enhanced the efficiency of new bone formation, and this was confirmed using bone mineral density (BMD) and biomechanical evaluation, particularly at 8 weeks after implantation. We demonstrated that the TGF-ß1­SF-CS scaffolds possessed as good biocompatibility and osteogenesis as the hybrid ones. Taken together, these findings indicate that the TGF-ß1-SF-CS scaffolds fulfilled the basic requirements of bone tissue engineering, and have the potential to be applied in orthopedic, reconstructive and maxillofacial surgery. Thus, TGF-ß1-SF-CS composite scaffolds represent a promising, novel type of scaffold for use in bone tissue engineering.

Construction and in vitro characterization of three-dimensional silk fibroinchitosan scaffolds.

The objective of this study was to discuss the construction method, characterization, and biocompatibility of three-dimensional silk fibroin-chitosan (SF-CS) scaffolds which met the requirements of bone tissue engineering scaffolds. Silk fibroin (SF) and chitosan (CS) were mixed at different ratios -3 to 7, 5 to 5, and 7 to 3- to fabricate the composite materials. To find out the optimum mixing ratio of SF and CS, parameters such as pore size, porosity, water absorption, and the mechanical properties were evaluated. Osteoblast cells hFOB1.19 were seeded on SF-CS scaffolds and pure CS scaffolds for the first time. Cell adhesion rate, cell proliferation, and cell activity were evaluated, and cell growth and formation of mineralized nodules were observed. Results showed that SF-CS scaffolds are a suitable candidate for bone tissue engineering.