Bone repair materials for the effective treatment of bone defects should simultaneously possess excellent biocompatibility and promote osteogenic differentiation. Herein, we prepared pifithrin-α-loaded layered double hydroxide/chitosan (PFTα–LDH–CS) nanohybrid composites for the first time according to the following steps: (i) the immersion of LDH nanoplates and PFTα in a CS solution; and (ii) the self-assembly synthesis of PFTα–LDH–CS nanohybrid composites after the pH value of the mixed solution was adjusted to 7.4. Interestingly, the LDH nanoplates with a thickness of ∼20 nm and width of ∼300 nm agglomerated together into flower-like shapes by self-assembly, and the CS was dispersed around the LDH nanoplates. The mesopores with the pore size of 3.95 nm among the LDH nanoplates served as channels for loading PFTα. Moreover, the CS around the LDH nanoplates increased the drug loading efficiency and drug sustained release property compared with the pure LDH nanoplates. The in vitro tests demonstrated that the human bone marrow-derived mesenchymal stem cells (hBMSCs) had good adhesion, spreading and proliferating on the LDH–CS and PFTα–LDH–CS, suggesting that both samples had the desired cytocompatibility. Note that the PFTα released from the PFTα–LDH–CS rapidly improved the cell proliferation, ALP activity, ECM mineralization and protein level of the Runt-related transcription factor 2 (RUNX2) and β-catenin. The enhanced osteogenic differentiation of hBMSCs on the PFTα–LDH–CS may be attributed to the PFTα released from the abovementioned nanohybrid composites, which resulted in the accumulation of β-catenin and activation of the β-catenin-mediated transcription activity in the cell nucleus. Therefore, the PFTα–LDH–CS nanohybrid composites with excellent cytocompatibility and enhanced osteoinductivity have great applications for novel bone repair materials.

Poor bone formation remains a key risk factor associated with acellular scaffolds that occurs in some bone defects, particularly in patients with metabolic bone disorders and local osteoporosis. We herein fabricated for the first time layered double hydroxide-chitosan porous scaffolds loaded with PFTα (LDH-CS-PFTα scaffolds) as therapeutic bone scaffolds for the controlled release of PFTα to enhance stem cell osteogenic differentiation and bone regeneration. The LDH-CS scaffolds had three-dimensional interconnected macropores, and plate-like LDH nanoparticles were uniformly dispersed within or on the CS films. The LDH-CS scaffolds exhibited appropriate PFTα drug delivery due to hydrogen bonding among LDH, CS and PFTα. In vitro functional studies demonstrated that the PFTα molecules exhibited potent ability to induce osteogenesis of hBMSCs via the GSK3β/β-catenin pathway, and the LDH-CS-PFTα scaffolds significantly enhanced the osteogenic differentiation of hBMSCs. In vivo studies revealed significantly increased repair and regeneration of bone tissue in cranial defect model rats compared to control rats at 12 weeks post-implantation. In conclusion, the LDH-CS-PFTα scaffolds exhibited excellent osteogenic differentiation and bone regeneration capability and hold great potential for applications in defined local bone regeneration.

•We fabricate strontium hydroxyapatite/chitosan nanohybrid scaffolds.•Ca5Sr5(PO4)6(OH)2 nanocrystals in scaffolds enhance osteogenic differentiation.•3D interconnected macropores improve cell adhesion and spreading.•Nanohybrid scaffold has a great potential for bone tissue engineering.For the clinical application of bone tissue engineering with the combination of biomaterials and mesenchymal stem cells (MSCs), bone scaffolds should possess excellent biocompatibility and osteoinductivity to accelerate the repair of bone defects. Herein, strontium hydroxyapatite [SrHAP, Ca10 − xSrx(PO4)6(OH)2]/chitosan (CS) nanohybrid scaffolds were fabricated by a freeze-drying method. The SrHAP nanocrystals with the different x values of 0, 1, 5 and 10 are abbreviated to HAP, Sr1HAP, Sr5HAP and Sr10HAP, respectively. With increasing x values from 0 to 10, the crystal cell volumes and axial lengths of SrHAP become gradually large because of the greater ion radius of Sr2 + than Ca2 +, while the crystal sizes of SrHAP decrease from 70.4 nm to 46.7 nm. The SrHAP/CS nanohybrid scaffolds exhibits three-dimensional (3D) interconnected macropores with pore sizes of 100–400 μm, and the SrHAP nanocrystals are uniformly dispersed within the scaffolds. In vitro cell experiments reveal that all the HAP/CS, Sr1HAP/CS, Sr5HAP/CS and Sr10HAP/CS nanohybrid scaffolds possess excellent cytocompatibility with the favorable adhesion, spreading and proliferation of human bone marrow mesenchymal stem cells (hBMSCs). The Sr5HAP nanocrystals in the scaffolds do not affect the adhesion, spreading of hBMSCs, but they contribute remarkably to cell proliferation and osteogenic differentiation. As compared with the HAP/CS nanohybrid scaffold, the released Sr2 + ions from the SrHAP/CS nanohybrid scaffolds enhance alkaline phosphatase (ALP) activity, extracellular matrix (ECM) mineralization and osteogenic-related COL-1 and ALP expression levels. Especially, the Sr5HAP/CS nanohybrid scaffolds exhibit the best osteoinductivity among four groups because of the synergetic effect between Ca2 + and Sr2 + ions. Hence, the Sr5HAP/CS nanohybrid scaffolds with excellent cytocompatibility and osteogenic property have promising application for bone tissue engineering.

Rheumatoid arthritis (RA) is a chronic disease affecting daily life of numerous patients, and uncontrolled proliferation of synovial fibroblasts plays vital role during the pathology of RA. Platelet-rich plasma (PRP), widely used in tissue regeneration and pain management, is rarely studied in RA. This study aims to investigate the effect of PRP on synovial fibroblasts during RA. Rheumatoid fibroblast-like synoviocyte MH7A cells were stimulated by lipopolysaccharide (LPS) to simulate RA conditions and treated with PRP, after that the concentration of inflammatory factors interleukin (IL) 1β, tumor necrosis factor alpha (TNFα) and IL6 in the supernatant of culture medium was quantified by ELISA. MTT assay, flow cytometry and tube formation assay were performed to assess changes in cell viability, apoptosis and effect on angiogenesis in vitro, respectively. Besides, the expression levels of main factors in the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signal pathway were examined. Results showed that PRP markedly inhibited the production of IL1β, TNFα and IL6 (P < 0.05) that was stimulated by LPS. LPS promoted MH7A cell viability, inhibited apoptosis and accelerated angiogenesis in vitro, while PRP could markedly relieve these effects (P < 0.05). The mRNA and protein levels of AKT1, PI3K (p58) and nuclear factor κ beta were elevated by LPS and then suppressed by PRP (P < 0.01). This study uncovered the potential of PRP in inhibiting inflammation, repressing synovial fibroblasts and regulating the PI3K/AKT signaling, providing basic proof for future application of PRP in managing RA. Further investigation is necessary to reveal detailed mechanism of PRP.

Functionalization of biomaterials with specific functional groups is one of the most straightforward strategies to induce specific cell responses to biomaterials. In this study, thiol (SH) and amino (NH2) functional groups have been successfully modified on the surfaces of mesoporous bioactive glass (MBG) scaffolds to form thiol-functionalized MBG (SH-MBG) and amino-functionalized MBG (NH2-MBG) scaffolds by a post-grafting technique. The effects of the functional groups on the structure, physicochemical and biological properties of MBG scaffolds were systematically investigated. The results showed that the functionalization of MBG scaffolds did not change their structures, and the SH-MBG and NH2-MBG scaffolds still had hierarchical pore architecture (macropores of 300–500 μm and mesopores of 3.5–4 nm) and high porosity (84–86%), similar to the MBG scaffolds. Furthermore, the SH-MBG and NH2-MBG scaffolds possessed similar apatite mineralization ability and biocompatibility compared to the MBG scaffolds. Importantly, the SH-MBG and NH2-MBG scaffolds significantly stimulated adhesion, proliferation and differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs). Therefore, functionalization of MBG scaffolds with SH and NH2 functional groups would be a viable way to tailor the surface characteristics for stimulating biological responses of hBMSCs, and the functionalized MBG scaffolds would be a promising bioactive material for bone tissue engineering applications.

The fabrication of bone scaffolds with interconnected porous structure, adequate mechanical properties, excellent biocompatibility and osteoinductivity presents a great challenge. Herein, a hybrid nanostructured hydroxyapatite–chitosan (HA–CS) composite scaffold has been fabricated according to the following steps: (i) the deposition of brushite–CS on a CS fibre porous scaffold by a dip-coating method; and (ii) the formation of a hybrid nanostructured HA–CS composite scaffold by the in situ conversion of brushite to HA using a bioinspired mineralization process. The hybrid HA–CS composite scaffold possesses three-dimensional (3D) interconnected pores with pore sizes of 30–80 μm. The HA rods with a length of ∼200 nm and width of ∼50 nm are perpendicularly oriented to the CS fibres. Interestingly, the abovementioned HA rods are composed of many smaller nanorods with a length of ∼40 nm and width of ∼10 nm oriented along the c-axis. The hybrid nanostructured HA–CS composite scaffold exhibits good mechanical properties with a compression strength of 9.41 ± 1.63 MPa and an elastic modulus of 0.17 ± 0.02 GPa, which are well-matched to those of trabecular bone. The influences of the hybrid HA–CS composite scaffold on cells have been investigated using human bone marrow stem cells (hBMSCs) as cell model and the CS fibre porous scaffold as the control sample. The hybrid HA–CS composite scaffold not only supports the adhesion and proliferation of hBMSCs, but also improves the osteoinductivity. The alkaline phosphatase activity and mineralization deposition on the hybrid HA–CS composite scaffold are higher than those on the CS fibre porous scaffold. Moreover, the hybrid HA–CS composite scaffold can promote the formation of new bone in rat calvarial defects as compared with the CS fibre porous scaffold. The excellent biocompatibility, osteoinductivity and mechanical properties suggest that the hybrid nanostructured HA–CS composite scaffold has great potential for bone tissue engineering.

Platelet-rich plasma (PRP) has been widely used for decades in the clinic, since an abundance of growth factors can be released when it is activated. However, its clinical use is limited because the release of growth factors is temporal and PRP lacks mechanical strength. The aim of this study was to incorporate PRP-derived growth factors into PCL/gelatin nanofibers using the emulsion electrospinning method to determine how growth factors are released from the scaffolds and how the presence of these factors enhances the bioactivity of the scaffolds. Scaffolds with or without PRP were prepared and characterized. The release of proteins from scaffolds over time and rabbit BMSC chemotaxis, proliferation, and chondrogenic induction were quantified in vitro. The in vivo restoring effect of the scaffolds was also evaluated by transplanting the scaffolds into a cartilage defect in an animal model, and the outcomes were determined by histological assessment, micro-CT scanning, and IL-1 measurement. The results showed that the mechanical properties of the scaffolds were mildly compromised due to the addition of PRP, and that the sustained release of growth factors from PRP-containing scaffolds occurred up to ∼30 days in culture. The scaffold bioactivity was enhanced, as BMSCs demonstrated increased proliferation and notable chemotaxis in the presence of PRP. Chondrogenesis of BMSCs was also promoted when the cells were cultured on the PRP scaffolds. Furthermore, the PRP scaffolds showed better restorative effects on cartilage defects, as well as anti-inflammatory effects in the joint cavity (the IL-1 level was decreased). In conclusion, the results of the current study indicate the potential for using a PRP-containing electrospun nanofibrous scaffold as a bioactive scaffold, which is beneficial for optimizing the clinical application of PRP.

Angiogenesis–osteogenesis coupling processes are vital in bone tissue engineering. Normal biomaterials implanted in bone defects have issues in the sufficient formation of blood vessels, especially in the central part. Single delivery of vascular endothelial growth factors (VEGF) to foci in previous studies did not show satisfactory results due to low loading doses, a short protein half-life and low efficiency. Development of a hypoxia-mimicking microenvironment for cells by local prolyl-4-hydroxylase inhibitor release, which can stabilize hypoxia-inducible factor 1α (HIF-1α) expression, is an alternative method. The aim of this study was to design a dimethyloxallyl glycine (DMOG) delivering scaffold composed of mesoporous bioactive glasses and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) polymers (MPHS scaffolds), so as to investigate whether the sustained release of DMOG promotes local angiogenesis and bone healing. The morphology and microstructure of composite scaffolds were characterized. The DMOG release patterns from scaffolds loaded with different DMOG dosages were evaluated, and the effects of DMOG delivery on human bone marrow stromal cell (hBMSC) adhesion, viability, proliferation, osteogenic differentiation and angiogenic-relative gene expressions with scaffolds were also investigated. In vivo studies were carried out to observe vascular formations and new bone ingrowth with DMOG-loaded scaffolds. The results showed that DMOG could be released in a sustained manner over 4 weeks from MPHS scaffolds and obviously enhance the angiogenesis and osteogenesis in the defects. Microfil perfusion showed a significantly increased formation of vessels in the defects with DMOG delivery. Furthermore, micro-CT imaging and fluorescence labeling indicated larger areas of bone formation for DMOG-loaded scaffolds. It is concluded that MPHS–DMOG scaffolds are promising for enhancing bone healing of osseous defects.

During the biomineralization process of bone minerals, amorphous calcium phosphate (ACP) is converted to apatite crystals by using octacalcium phosphate (OCP) and brushite (DCPD) as transitory precursors, resulting in the formation of hybrid nanostructured collagen/apatite composites. Herein, we report, for the first time, the bioinspired synthesis of a collagen/hydroxyapatite (HA) porous scaffold (CHPS) according to the following stages: (i) fabrication of collagen fibre porous scaffold (CFPS) by a needle-punching process; (ii) deposition of brushite/chitosan (DCPD/CS) on CHPS by a dip-coating method; and (iii) formation of CHPS by in situ conversion of DCPD to HA. The CHPS exhibits three-dimensional (3D) interconnected porous structures with pore sizes of around 60 μm. HA crystals distribute homogeneously on the CHPS, and display wheat-like shapes with a length of approximately 200 nm and a width of approximately 80 nm. The in vitro cell tests by using human bone marrow stromal cells (hBMSCs) indicate that the HA crystals in the CHPS not only promote the cell adhesion and proliferation of the hBMSCs, but also stimulate osteogenic differentiation. The in vivo results reveal that the CHPS exhibits better osteoinductivity than the CFPS because of its similar chemical components, crystallinity and crystallographic texture to natural bone. Moreover, the CHPS can stimulate new bone formation in rat critical-sized calvarial defects within 8 weeks. The CHPS possesses a favourable pore structure, and excellent biocompatibility and osteoinductivity, and thus it has great potential applications for bone tissue engineering.

In this study, three-dimensional (3D) magnetic Fe3O4 nanoparticles containing mesoporous bioactive glass/polycaprolactone (Fe3O4/MBG/PCL) composite scaffolds have been fabricated by the 3D-printing technique. The physiochemical properties, in vitro bioactivity, anticancer drug delivery, mechanical strength, magnetic heating ability and cell response of Fe3O4/MBG/PCL scaffolds were systematically investigated. The results showed that Fe3O4/MBG/PCL scaffolds had uniform macropores of 400 μm, high porosity of 60% and excellent compressive strength of 13–16 MPa. The incorporation of magnetic Fe3O4 nanoparticles into MBG/PCL scaffolds did not influence their apatite mineralization ability but endowed excellent magnetic heating ability and significantly stimulated proliferation, alkaline phosphatase (ALP) activity, osteogenesis-related gene expression (RUNX2, OCN, BSP, BMP-2 and Col-1) and extra-cellular matrix (ECM) mineralization of human bone marrow-derived mesenchymal stem cells (h-BMSCs). Moreover, using doxorubicin (DOX) as a model anticancer drug, Fe3O4/MBG/PCL scaffolds exhibited a sustained drug release for use in local drug delivery therapy. Therefore, the 3D-printed Fe3O4/MBG/PCL scaffolds showed the potential multifunctionality of enhanced osteogenic activity, local anticancer drug delivery and magnetic hyperthermia.

Development of bioactive scaffolds with controllable architecture and high osteogenic capability for bone tissue engineering is hotly pursued. In this study, three-dimensional (3D) mesoporous bioactive glass (MBG) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) composite scaffolds with well-defined pore structures and high compressive strength (∼5–12 MPa) were synthesized by a 3D printing technique. Compared to reported polymer-bonded MBG scaffolds, the incorporation of the biocompatible PHBHHx polymer as a particle binder enhanced their bioactive and osteogenic properties, including fast apatite-forming ability, and promoted human bone marrow-derived mesenchymal stem cell (hBMSC) adhesion, proliferation, alkaline phosphatase (ALP) activity and bone-related gene expression. Furthermore, MBG/PHBHHx composite scaffolds were explored to repair critical-size rat calvarial defects. The results showed that MBG/PHBHHx composite scaffolds exhibited a controlled degradation rate and more significant potential to stabilize the pH environment with increasing PHBHHx ratio. At 8 weeks post-implantation, MBG/PHBHHx scaffolds were demonstrated to stimulate bone regeneration in the calvarial defects and have largely repaired them through analysis of micro-CT, sequential fluorescent labeling and histology. These results lay a potential framework for future study by using modified MBG/PHBHHx-based functional scaffolds to improve the osteogenic activity and bone defect restoration.

•The structural energetics and dynamics of TGF-β–receptor complex is characterized in detail.•A binding loop is identified to play an essential role in the peptide-mediated complex interaction.•The loop segment is cyclized and optimized to obtain potent cyclic peptide binders of TGF-β.The human TGF-β/SMAD7 signaling has been recognized as an attractive target of heterotopic ossification (HO). Here, we report a successful rational design of cyclic peptides to disrupt the signaling pathway by targeting TGF-β–receptor complex. The intermolecular interaction between TGF-β and its cognate receptor is characterized in detail using molecular dynamics simulation, binding energetic analysis, and alanine scanning. With the computational analysis a binding loop of receptor protein is identified that plays an essential role in the peptide-mediated TGF-β–receptor interaction. Subsequently, the loop is stripped from the protein context to generate a linear peptide segment, which possesses considerable flexibility and intrinsic disorder, and thus would incur a large entropy penalty upon binding to TGF-β. In order to minimize the unfavorable entropic effect, the linear peptide is cyclized by adding a disulfide bond between the N- and C-terminal cysteine residues of the peptide, resulting in a cyclic peptide. In vitro fluorescence anisotropy assays substantiate that the cyclic peptide can bind tightly to TGF-β with determined Kd value of 54 μM. We also demonstrated that structural optimization can further improve the peptide affinity by site-directed mutagenesis of selected residues based on the computationally modeled complex structure of TGF-β with the cyclic peptide.

ObjectivesTo analyze the differences in microarchitecture and bone remodeling of subchondral bone in femoral heads from patients with rheumatoid arthritis (RA) and osteoarthritis (OA).DesignsPeri-articular bone samples, including subchondral trabecular bone (STB) and deeper trabecular bone (DTB) were extracted from the load-bearing region of femoral heads from 20 patients with RA and 40 patients with OA during hip replacement surgery. Micro-CT, histomorphometry and backscatter scanning electron microscopy (BSEM) were performed to assess microarchitecture and bone histology parameters.ResultsIn both RA and OA, STB showed more sclerotic microarchitecture and more active bone remodeling, compared to DTB. RA and OA showed similar microarchitecture characteristics in both STB and DTB, despite STB in RA exhibiting higher bone resorption. In addition, there was no difference in the frequency of bone cysts in STB between RA and OA. In STB, the trabecular bone surrounding subchondral bone cysts (Cys-Tb) was more sclerotic than the trabecular bone found distant to cysts (Peri-Tb), with a higher level of bone remodeling. Both Cys-Tb region and Peri-Tb region were detected to have similar microarchitectural and bone remodeling characteristics in RA and OA.ConclusionsApart from higher bone resorption in the general subchondral bone of RA samples, the peri-articular bone exhibited similar microarchitectural and bone remodeling characteristics in RA and OA.

ObjectivesTo analyze the differences in microarchitecture and bone remodeling of subchondral bone in femoral heads from patients with rheumatoid arthritis (RA) and osteoarthritis (OA).DesignsPeri-articular bone samples, including subchondral trabecular bone (STB) and deeper trabecular bone (DTB) were extracted from the load-bearing region of femoral heads from 20 patients with RA and 40 patients with OA during hip replacement surgery. Micro-CT, histomorphometry and backscatter scanning electron microscopy (BSEM) were performed to assess microarchitecture and bone histology parameters.ResultsIn both RA and OA, STB showed more sclerotic microarchitecture and more active bone remodeling, compared to DTB. RA and OA showed similar microarchitecture characteristics in both STB and DTB, despite STB in RA exhibiting higher bone resorption. In addition, there was no difference in the frequency of bone cysts in STB between RA and OA. In STB, the trabecular bone surrounding subchondral bone cysts (Cys-Tb) was more sclerotic than the trabecular bone found distant to cysts (Peri-Tb), with a higher level of bone remodeling. Both Cys-Tb region and Peri-Tb region were detected to have similar microarchitectural and bone remodeling characteristics in RA and OA.ConclusionsApart from higher bone resorption in the general subchondral bone of RA samples, the peri-articular bone exhibited similar microarchitectural and bone remodeling characteristics in RA and OA.

•We fabricated core-shell ZSM-5/chitosan ellipsoids loaded with pifithrin-α.•ZSM-5 ellipsoids exhibit hierarchical nanostructures composed of nanocrystals.•ZSM-5/CS/PFTα ellipsoids serve as drug delivery systems.•The released PFTα from composite ellipsoids enhanced osteoinductivity.•PFTα disrupts the ubiquitin-proteasome mediated degradation of β-catenin.For enhanced osteoinductivity to treat effectively with bone defects, the design and fabrication of novel drug delivery systems remain a great challenge. Herein, we for the first time fabricated core-shell ZSM-5/chitosan ellipsoids loaded with pifithrin-α (ZSM-5/CS/PFTα ellipsoids). The ZSM-5 ellipsoids with long-axis lengths of ~ 400 nm and short-axis lengths of ~ 300 nm are constructed by many nanocrystals. The micropores and mesopores that exist respectively within and among the ZSM-5 nanocrystals serve as channels for loading PFTα. The CS on the ZSM-5/CS/PFTα ellipsoids increases drug loading efficiency up to 91.0%, and improves drug sustained release property. The ZSM-5/CS/PFTα ellipsoids possess excellent cytocompatibility, and promote the adhesion, spreading and proliferation of human bone mesenchymal stem cells (hBMSCs). Moreover, the released PFTα from the ZSM-5/CS/PFTα ellipsoids improves the ALP activity of hBMSCs, the mRNA relative expression levels of COL1, OCN and RUNX2, the ECM mineralization and the protein level of β-catenin. The reason is attributed to the fact that the released PFTα as a p53 inhibitor disrupts the ubiquitin-proteasome mediated degradation of β-catenin, resulting in the significant accumulation of β-catenin and the downstream transcription of genes involved in cell survival, proliferation and osteogenic differentiation.Download high-res image (264KB)Download full-size image

Angiogenesis–osteogenesis coupling processes are vital in bone tissue engineering. Normal biomaterials implanted in bone defects have issues in the sufficient formation of blood vessels, especially in the central part. Single delivery of vascular endothelial growth factors (VEGF) to foci in previous studies did not show satisfactory results due to low loading doses, a short protein half-life and low efficiency. Development of a hypoxia-mimicking microenvironment for cells by local prolyl-4-hydroxylase inhibitor release, which can stabilize hypoxia-inducible factor 1α (HIF-1α) expression, is an alternative method. The aim of this study was to design a dimethyloxallyl glycine (DMOG) delivering scaffold composed of mesoporous bioactive glasses and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) polymers (MPHS scaffolds), so as to investigate whether the sustained release of DMOG promotes local angiogenesis and bone healing. The morphology and microstructure of composite scaffolds were characterized. The DMOG release patterns from scaffolds loaded with different DMOG dosages were evaluated, and the effects of DMOG delivery on human bone marrow stromal cell (hBMSC) adhesion, viability, proliferation, osteogenic differentiation and angiogenic-relative gene expressions with scaffolds were also investigated. In vivo studies were carried out to observe vascular formations and new bone ingrowth with DMOG-loaded scaffolds. The results showed that DMOG could be released in a sustained manner over 4 weeks from MPHS scaffolds and obviously enhance the angiogenesis and osteogenesis in the defects. Microfil perfusion showed a significantly increased formation of vessels in the defects with DMOG delivery. Furthermore, micro-CT imaging and fluorescence labeling indicated larger areas of bone formation for DMOG-loaded scaffolds. It is concluded that MPHS–DMOG scaffolds are promising for enhancing bone healing of osseous defects.

The properties of bone scaffolds, including biocompatibility, osteoinductivity and antibacterial activity, are of great importance for reconstruction of large bone defects and prevention of implant-associated infections. Herein, we develop an Ag-loaded strontium hydroxyapatite (SrHAP)/chitosan (CS) porous scaffold (Ag–SrHAP/CS) according to the following steps: (i) freeze-drying fabrication of a SrHAP/CS porous scaffold; and (ii) deposition of Ag nanoparticles on the above scaffold. In addition, HAP/CS and Ag–HAP/CS porous scaffolds are prepared under the same conditions without doping Sr element. All the HAP/CS, Ag–HAP/CS, SrHAP/CS and Ag–SrHAP/CS porous scaffolds provide a friendly environment for the adhesion, spreading and proliferation of human bone marrow mesenchymal stem cells (hBMSCs). The three-dimensional (3D) interconnected macropores with a pore size of 100–400 μm allow the spreading of hBMSCs throughout the whole scaffolds. Interestingly, the Sr ions and Ag ions released from the Ag–SrHAP/CS porous scaffolds significantly enhance their osteoinductivity and antibacterial activity, respectively. The Sr element in the SrHAP/CS and Ag–SrHAP/CS porous scaffolds increase the alkaline phosphatase (ALP) activity of hBMSCs, extracellular matrix (ECM) mineralization, and the expression levels of osteogenic-related genes BMP-2 and COL-I. Moreover, the Ag ions released from the Ag–HAP/CS and Ag–SrHAP/CS scaffolds can effectively inhibit the growth and attachment of Staphylococcus aureus (S. aureus, ATCC 25923). In conclusion, the Ag–SrHAP/CS porous scaffold possesses excellent biocompatibility, osteoinductivity and antibacterial activity, so it has great potential for application in bone tissue engineering to repair bone defects and avoid infections.

Bone repair materials for the effective treatment of bone defects should simultaneously possess excellent biocompatibility and promote osteogenic differentiation. Herein, we prepared pifithrin-α-loaded layered double hydroxide/chitosan (PFTα–LDH–CS) nanohybrid composites for the first time according to the following steps: (i) the immersion of LDH nanoplates and PFTα in a CS solution; and (ii) the self-assembly synthesis of PFTα–LDH–CS nanohybrid composites after the pH value of the mixed solution was adjusted to 7.4. Interestingly, the LDH nanoplates with a thickness of ∼20 nm and width of ∼300 nm agglomerated together into flower-like shapes by self-assembly, and the CS was dispersed around the LDH nanoplates. The mesopores with the pore size of 3.95 nm among the LDH nanoplates served as channels for loading PFTα. Moreover, the CS around the LDH nanoplates increased the drug loading efficiency and drug sustained release property compared with the pure LDH nanoplates. The in vitro tests demonstrated that the human bone marrow-derived mesenchymal stem cells (hBMSCs) had good adhesion, spreading and proliferating on the LDH–CS and PFTα–LDH–CS, suggesting that both samples had the desired cytocompatibility. Note that the PFTα released from the PFTα–LDH–CS rapidly improved the cell proliferation, ALP activity, ECM mineralization and protein level of the Runt-related transcription factor 2 (RUNX2) and β-catenin. The enhanced osteogenic differentiation of hBMSCs on the PFTα–LDH–CS may be attributed to the PFTα released from the abovementioned nanohybrid composites, which resulted in the accumulation of β-catenin and activation of the β-catenin-mediated transcription activity in the cell nucleus. Therefore, the PFTα–LDH–CS nanohybrid composites with excellent cytocompatibility and enhanced osteoinductivity have great applications for novel bone repair materials.

The fabrication of bone scaffolds with interconnected porous structure, adequate mechanical properties, excellent biocompatibility and osteoinductivity presents a great challenge. Herein, a hybrid nanostructured hydroxyapatite–chitosan (HA–CS) composite scaffold has been fabricated according to the following steps: (i) the deposition of brushite–CS on a CS fibre porous scaffold by a dip-coating method; and (ii) the formation of a hybrid nanostructured HA–CS composite scaffold by the in situ conversion of brushite to HA using a bioinspired mineralization process. The hybrid HA–CS composite scaffold possesses three-dimensional (3D) interconnected pores with pore sizes of 30–80 μm. The HA rods with a length of ∼200 nm and width of ∼50 nm are perpendicularly oriented to the CS fibres. Interestingly, the abovementioned HA rods are composed of many smaller nanorods with a length of ∼40 nm and width of ∼10 nm oriented along the c-axis. The hybrid nanostructured HA–CS composite scaffold exhibits good mechanical properties with a compression strength of 9.41 ± 1.63 MPa and an elastic modulus of 0.17 ± 0.02 GPa, which are well-matched to those of trabecular bone. The influences of the hybrid HA–CS composite scaffold on cells have been investigated using human bone marrow stem cells (hBMSCs) as cell model and the CS fibre porous scaffold as the control sample. The hybrid HA–CS composite scaffold not only supports the adhesion and proliferation of hBMSCs, but also improves the osteoinductivity. The alkaline phosphatase activity and mineralization deposition on the hybrid HA–CS composite scaffold are higher than those on the CS fibre porous scaffold. Moreover, the hybrid HA–CS composite scaffold can promote the formation of new bone in rat calvarial defects as compared with the CS fibre porous scaffold. The excellent biocompatibility, osteoinductivity and mechanical properties suggest that the hybrid nanostructured HA–CS composite scaffold has great potential for bone tissue engineering.

Functionalization of biomaterials with specific functional groups is one of the most straightforward strategies to induce specific cell responses to biomaterials. In this study, thiol (SH) and amino (NH2) functional groups have been successfully modified on the surfaces of mesoporous bioactive glass (MBG) scaffolds to form thiol-functionalized MBG (SH-MBG) and amino-functionalized MBG (NH2-MBG) scaffolds by a post-grafting technique. The effects of the functional groups on the structure, physicochemical and biological properties of MBG scaffolds were systematically investigated. The results showed that the functionalization of MBG scaffolds did not change their structures, and the SH-MBG and NH2-MBG scaffolds still had hierarchical pore architecture (macropores of 300–500 μm and mesopores of 3.5–4 nm) and high porosity (84–86%), similar to the MBG scaffolds. Furthermore, the SH-MBG and NH2-MBG scaffolds possessed similar apatite mineralization ability and biocompatibility compared to the MBG scaffolds. Importantly, the SH-MBG and NH2-MBG scaffolds significantly stimulated adhesion, proliferation and differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs). Therefore, functionalization of MBG scaffolds with SH and NH2 functional groups would be a viable way to tailor the surface characteristics for stimulating biological responses of hBMSCs, and the functionalized MBG scaffolds would be a promising bioactive material for bone tissue engineering applications.

Development of bioactive scaffolds with controllable architecture and high osteogenic capability for bone tissue engineering is hotly pursued. In this study, three-dimensional (3D) mesoporous bioactive glass (MBG) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) composite scaffolds with well-defined pore structures and high compressive strength (∼5–12 MPa) were synthesized by a 3D printing technique. Compared to reported polymer-bonded MBG scaffolds, the incorporation of the biocompatible PHBHHx polymer as a particle binder enhanced their bioactive and osteogenic properties, including fast apatite-forming ability, and promoted human bone marrow-derived mesenchymal stem cell (hBMSC) adhesion, proliferation, alkaline phosphatase (ALP) activity and bone-related gene expression. Furthermore, MBG/PHBHHx composite scaffolds were explored to repair critical-size rat calvarial defects. The results showed that MBG/PHBHHx composite scaffolds exhibited a controlled degradation rate and more significant potential to stabilize the pH environment with increasing PHBHHx ratio. At 8 weeks post-implantation, MBG/PHBHHx scaffolds were demonstrated to stimulate bone regeneration in the calvarial defects and have largely repaired them through analysis of micro-CT, sequential fluorescent labeling and histology. These results lay a potential framework for future study by using modified MBG/PHBHHx-based functional scaffolds to improve the osteogenic activity and bone defect restoration.

Platelet-rich plasma (PRP) has been widely used for decades in the clinic, since an abundance of growth factors can be released when it is activated. However, its clinical use is limited because the release of growth factors is temporal and PRP lacks mechanical strength. The aim of this study was to incorporate PRP-derived growth factors into PCL/gelatin nanofibers using the emulsion electrospinning method to determine how growth factors are released from the scaffolds and how the presence of these factors enhances the bioactivity of the scaffolds. Scaffolds with or without PRP were prepared and characterized. The release of proteins from scaffolds over time and rabbit BMSC chemotaxis, proliferation, and chondrogenic induction were quantified in vitro. The in vivo restoring effect of the scaffolds was also evaluated by transplanting the scaffolds into a cartilage defect in an animal model, and the outcomes were determined by histological assessment, micro-CT scanning, and IL-1 measurement. The results showed that the mechanical properties of the scaffolds were mildly compromised due to the addition of PRP, and that the sustained release of growth factors from PRP-containing scaffolds occurred up to ∼30 days in culture. The scaffold bioactivity was enhanced, as BMSCs demonstrated increased proliferation and notable chemotaxis in the presence of PRP. Chondrogenesis of BMSCs was also promoted when the cells were cultured on the PRP scaffolds. Furthermore, the PRP scaffolds showed better restorative effects on cartilage defects, as well as anti-inflammatory effects in the joint cavity (the IL-1 level was decreased). In conclusion, the results of the current study indicate the potential for using a PRP-containing electrospun nanofibrous scaffold as a bioactive scaffold, which is beneficial for optimizing the clinical application of PRP.

In this study, three-dimensional (3D) magnetic Fe3O4 nanoparticles containing mesoporous bioactive glass/polycaprolactone (Fe3O4/MBG/PCL) composite scaffolds have been fabricated by the 3D-printing technique. The physiochemical properties, in vitro bioactivity, anticancer drug delivery, mechanical strength, magnetic heating ability and cell response of Fe3O4/MBG/PCL scaffolds were systematically investigated. The results showed that Fe3O4/MBG/PCL scaffolds had uniform macropores of 400 μm, high porosity of 60% and excellent compressive strength of 13–16 MPa. The incorporation of magnetic Fe3O4 nanoparticles into MBG/PCL scaffolds did not influence their apatite mineralization ability but endowed excellent magnetic heating ability and significantly stimulated proliferation, alkaline phosphatase (ALP) activity, osteogenesis-related gene expression (RUNX2, OCN, BSP, BMP-2 and Col-1) and extra-cellular matrix (ECM) mineralization of human bone marrow-derived mesenchymal stem cells (h-BMSCs). Moreover, using doxorubicin (DOX) as a model anticancer drug, Fe3O4/MBG/PCL scaffolds exhibited a sustained drug release for use in local drug delivery therapy. Therefore, the 3D-printed Fe3O4/MBG/PCL scaffolds showed the potential multifunctionality of enhanced osteogenic activity, local anticancer drug delivery and magnetic hyperthermia.