Nuciferine prevents bone loss by disrupting multinucleated osteoclast formation and promoting type H vessel formation.

Recently, type H vessels were reported to couple angiogenesis and osteogenesis during osteoclastogenesis, and tartrate-resistant acid phosphatase (Trap)+ preosteoclasts were found to secrete increased PDGF-BB to promote type H vessel formation. Therefore, utilization of type H vessels may be a strategy to treat diseases involving bone loss. In the present study, we found that nuciferine, a natural bioactive compound, has various effects, including inhibiting osteoclastogenesis and promoting type H vessel formation. Nuciferine inhibited osteoclastogenesis and bone resorption but increased the relative number of Trap+ preosteoclasts. Nuciferine restrained the expression of osteoclast-specific genes and proteins, promoted PDGF-BB production and potentiated related angiogenic activities by inhibiting the MAPK and NF-κB signaling pathways in vitro. We confirmed the bone-protective effects of nuciferine in ovariectomized mice and found that nuciferine treatment increased the PDGF-BB concentration and the number of type H vessels in the femur. In conclusion, our results demonstrated that nuciferine can decrease multinucleated osteoclast formation and promote type H vessel formation through preservation of Trap+ preosteoclasts via inhibition of the MAPK and NF-κB signaling pathways and may be an excellent agent for the treatment of diseases involving bone loss.

A Study to Compare the Efficacy of a Biodegradable Dynamic Fixation System With Titanium Devices in Posterior Spinal Fusion Between Articular Processes in a Canine Model.

The objective of this study was to apply a biodegradable dynamic fixation system (BDFS) for lumbar fusion between articular processes and compare the fusion results and biomechanical changes with those of conventional rigid fixation. Twenty-four mongrel dogs were randomly assigned to 2 groups and subjected to either posterior lumbar fusion surgery with a BDFS or titanium rods (TRs) at the L5-L6 segments. Six animals in each group were sacrificed at 8 or 16 weeks. Fusion conditions were evaluated by computed tomography (CT), manual palpation, biomechanical tests, and histological analysis. Biomechanical tests were performed at the L4-7 (for range of motion (ROM)) and L5-6 (for fusion stiffness) segments. Histological examination was performed on organs, surrounding tissues, and the fused area. The magnesium alloy components maintained their initial shape 8 weeks after the operation, but the meshing teeth were almost completely degraded at 16 weeks. The biomechanical analysis revealed an increased lateral bending ROM at 8 weeks and axial torsion ROM at 16 weeks. The L4-5 extension-flexion ROMs in the BDFS group were 2.29 ± 0.86 deg and 3.17 ± 1.08 deg at 16 weeks, respectively, compared with 3.22 ± 0.56 deg and 5.55 ± 1.84 deg in TR group. However, both groups showed similar fusion results. The BDFS design is suitable, and its degradation in vivo is safe. The BDFS can be applied for posterior lumbar fusion between articular processes to complete the fusion well. Additionally, the BDFS can reduce the decline in lateral motion and hypermotion of the cranial adjacent segment in flexion-extension motion.

A novel dynamic fixation system with biodegradable components on lumbar fusion between articular processes in a canine model.

The objective of this study was to design a novel dynamic fixation system with biodegradable components, apply it for lumbar fusion between articular processes and compare the fusion results and biomechanical changes to those of conventional rigid fixation. The novel dynamic fixation system was designed using a finite element model, stress distributions were compared and 24 mongrel dogs were randomly assigned to two groups and subjected to either posterior lumbar fusion surgery with a novel dynamic fixation system or titanium rods at the L5-L6 segments. Lumbar spines were assessed in both groups to detect radiographic, manual palpation and biomechanical changes. Histological examination was performed on organs and surrounding tissues. In the novel dynamic fixation system, stress was mainly distributed on the meshing teeth of the magnesium alloy spacer. The magnesium alloy components maintained their initial shape 8 weeks after the operation, but the meshing teeth were almost completely degraded at 16 weeks. The novel dynamic fixation system revealed an increased lateral bending range of motion at 8 weeks; however, both groups showed similar radiographic grades, fusion stiffness, manual palpation and histological results. The novel dynamic fixation system design is suitable, and its degradation in vivo is safe. The novel dynamic fixation system can be applied for posterior lumbar fusion between articular processes and complete the fusion like titanium rods.

A modular programmed biphasic dual-delivery system on 3D ceramic scaffolds for osteogenesis in vitro and in vivo.

Single-factor delivery is the most common characteristic of bone tissue engineering techniques. However, bone regeneration is a complex process requiring multiple factors and specialized release mechanisms. Therefore, the development of a dual-delivery system allowing for programmed release kinetics would be highly desirable. Improvement of the molarity and versatility of the delivery system has rarely been studied. Herein, we report the development of a novel, modular programmed biphasic dual-release system (SCB), carrying a BMP2 and an engineered collagen I-derived recognition motif (Stath-DGEA), with a self-remodification feature on hydroxyapatite (HA)-based materials. The SCB system was loaded onto an additive manufactured (AM) scaffold in order to evaluate its bifactor osteogenic potential and its biphasic release behavior. Further, the biomechanical properties of the scaffold were studied by using the fluid-structure interaction (FSI) method. Section fluorescent labeling revealed that the HA scaffold has a relatively higher density and efficiency. Additionally, the results of the release and inhibition experiment suggested that the SCB system could facilitate the sustained release of therapeutic levels of two factors during the initial stage of implantation, thereby exhibiting a rapid high-dose release pattern at a specific time point during the second stage. The FSI prediction model indicated that the scaffold provides an excellent biomimetic mechanical and fluid dynamic microenvironment to promote osteogenesis. Our results indicated that incorporation of BMP2 with Stath-DGEA in the biphasic SCB system could have a synergetic effect in promoting the adhesion, proliferation, and differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro, under staged stimulations. Further, in vivo studies in both ectopic and orthotopic rat models showed that the SCB system loaded onto an AM scaffold could enhance osteointegration and osteoinduction throughout the osteogenic process. Thus, the novel synthetic SCB system described herein used on an AM scaffold provides a biomimetic extracellular environment that enhances bone regeneration and is a promising multifunctional, dual-release platform.

Chitosan-Gelatin Scaffolds Incorporating Decellularized Platelet-Rich Fibrin Promote Bone Regeneration.

Platelet-rich fibrin (PRF), which functions as a growth factor carrier, has been extensively used to promote soft and hard tissue repair. However, whether decellularized PRF (DPRF) maintains its bioactive effects is unknown. Chitosan/gelatin(C/G) base scaffolds display appropriate biocompatibility and mechanical properties, but they lack biological activity. Thus, the incorporation of DPRF into the C/G scaffold can theoretically improve both the bioactivity of the C/G scaffold and the strength of PRF. In this study, DPRF was prepared using a method combining repeated freeze-thawing and enzymatic digestion. Also, DPRF-loaded chitosan-gelatin scaffolds (C/G/DPRF) were fabricated, using C/G scaffolds as controls. The osteogenic potential of scaffolds was investigated in vitro and in vivo. Compared with the C/G scaffold, C/G/DPRF had a larger pore size (280.8 ± 11.7 µm vs 235.0 ± 11.6 µm; P < 0.05), increased water uptake ratio (13.90 ± 0.09 vs 11.05 ± 0.10; P < 0.05), and similar porosity (90.50 ± 0.87 vs 90.65 ± 0.67; P > 0.05) but reduced compressive modulus (0.81 ± 0.02 MPa vs 1.17 ± 0.05 MPa; P < 0.05). In vitro, C/G/DPRF scaffolds accelerated attachment, proliferation, and osteogenesis-related marker expression of bone marrow stem cells. In vivo, C/G/DPRF scaffolds led to enhanced bone healing and defect closure in a rat calvarial defect model. Thus, we concluded that DPRF remains bioactive and the prepared C/G/DPRF scaffold is a promising material for bone regeneration.

A three-dimensional (3D) printed biomimetic hierarchical scaffold with a covalent modular release system for osteogenesis.

Hydroxyapatite (HA) ceramics are well known for their biocompatibility, bioactivity, and osteoconductive nature. However, limited hierarchical structure and lack of ease in modularity hinder the widespread application of conventional HA ceramics. By using three-dimensional printing (3DP) techniques with multiple materials, including HA, complex biological and mechanical architecture of natural organisms can be achieved through biomimetics. In this study, we designed an osteoid, biomimetic, hierarchical, porous HA ceramic 3D printed scaffold (3DPs). Further incorporation of a covalent, modular, controlled release system (CMR), based on Watson-Crick's complementary oligonucleotides, and was added to carry a bone morphogenetic protein-2 (BMP2) peptide. The choice of a HA biomimetic scaffold housing BMP2 protein fragments was selected to successfully promote osteogenesis both in vitro and in vivo. Scanning electron microscopy, micro-computed tomography analysis and computer fluid dynamics simulations of the 3DPs showed a uniform biomimetic hierarchical structure and an effective interior permeability. Active molecules were found bound with high stability and modular to the scaffold surface via the CMR system. After 7 days of incubation under physiological conditions, approximately 90% of active factors remained bound. Compared to control groups, the 3DPs-CMR-BMP2 group significantly enhanced cell proliferation and adhesion. Moreover, the 3DPs-CMR-BMP2 group exhibited more extensive and sustained osteogenic effects through upregulated expression of osteogenic factors and enhanced calcium deposition, as compared to study and control groups. Furthermore, ectopic osteogenesis and a critical calvarial defect model confirmed that the 3DPs-CMR-BMP2 group significantly promoted in vivo bone healing versus control. Thus, our results showed that biomimetic hierarchical 3DPs with a CMR system successfully promote cell proliferation, adhesion, differentiation and osteogenesis, on a continuous cycle. The biomimetic hierarchical 3DPs with a CMR system offers a promising multi-functional, bone substitute material for treatment of patients with bone defects.

Preparation and Characterization of a Chitosan/Gelatin/Extracellular Matrix Scaffold and Its Application in Tissue Engineering.

Previous studies have demonstrated that extracellular matrix (ECM) can be used in tissue engineering due to its bioactivity. However, adipose-derived ECM (A-dECM) has never been applied in bone tissue engineering, and it is unknown whether it would be beneficial to the growth of bone marrow mesenchymal stem cells (BMSCs). In this study, we produced chitosan/gelatin/A-dECM (C/G/A-dECM) scaffolds via lyophilization and crosslinking; chitosan/gelatin (C/G) scaffolds were used as controls. For the C/G/A-dECM scaffolds, the average pore size was 285.93 ± 85.39 µm; the average porosity was 90.62 ± 3.65%; the average compressive modulus was 0.87 ± 0.05 kPa; and the average water uptake ratio was 13.73 ± 1.16. In vitro, A-dECM scaffolds could promote the attachment and proliferation of BMSCs. In the same osteogenic-inducing reagent, better osteogenic differentiation could be observed for the C/G/A-dECM scaffolds than for the C/G scaffolds. Thus, we conclude that A-dECM is a promising material and that C/G/A-dECM scaffolds are a candidate for bone tissue engineering.