The effect of mesoporous bioglass on osteogenesis and adipogenesis of osteoporotic BMSCs

Osteoblast and osteoclast activity on collagen-based 3D printed scaffolds enriched with strontium-doped bioactive glasses and hydroxyapatite nanorods for bone tissue engineering

Bone tissue engineering (BTE) aims to promote bone regeneration by means of the synergistic effect of biomaterials, cells, and other factors, as potential alternative to conventional treatments for bone fractures. To this aim, a composite material was developed, based on collagen type I, strontium-enriched mesoporous bioactive glasses, and hydroxyapatite nanorods as bioactive and biomimetic components. Nanostructured scaffolds were 3D printed and subsequently chemically crosslinked with genipin to improve mechanical properties and stability. The developed nanostructured system was maintained in culture until 3 weeks with a co-culture of human bone cells to provide anex vivomodel of bone microenvironment and examine the cellular crosstalk and signaling pathways through paracrine cell activities. Human osteoblasts (OBs), derived from trabecular bone, and human osteoclast precursors (OCs), isolated from buffy coat samples were involved, with OBs seeded on the scaffold and OC precursors seeded in a transwell device. When compared to the material without inorganic components, the bioactive and biomimetic scaffold positively influenced cell proliferation and cell metabolic activity, boosting alkaline phosphatase activity of OBs, and reducing OC differentiation. Thus, the bioactive and biomimetic system promoted an enhanced cellular response, highlighting its potential application in BTE.

Enhancing osteoblast proliferation and bone regeneration by poly (amino acid)/selenium-doped hydroxyapatite

Among various biomaterials employed for bone repair, composites with good biocompatibility and osteogenic ability had received increasing attention from biomedical applications. In this study, we doped selenium (Se) into hydroxyapatite (Se-HA) by the precipitation method, and prepared different amounts of Se-HA-loaded poly (amino acid)/Se-HA (PAA/Se-HA) composites (0, 10 wt%, 20 wt%, 30 wt%) byin-situmelting polycondensation. The physical and chemical properties of PAA/Se-HA composites were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and their mechanical properties. XRD and FT-IR results showed that PAA/Se-HA composites contained characteristic peaks of PAA and Se-HA with amide linkage and HA structures. DSC and TGA results specified the PAA/Se-HA30 composite crystallization, melting, and maximum weight loss temperatures at 203.33 °C, 162.54 °C, and 468.92 °C, respectively, which implied good thermal stability. SEM results showed that Se-HA was uniformly dispersed in PAA. The mechanical properties of PAA/Se-HA30 composites included bending, compressive, and yield strengths at 83.07 ± 0.57, 106.56 ± 0.46, and 99.17 ± 1.11 MPa, respectively. The cellular responses of PAA/Se-HA compositesin vitrowere studied using bone marrow mesenchymal stem cells (BMSCs) by cell counting kit-8 assay, and results showed that PAA/Se-HA30 composites significantly promoted the proliferation of BMSCs at the concentration of 2 mg ml-1. The alkaline phosphatase activity (ALP) and alizarin red staining results showed that the introduction of Se-HA into PAA enhanced ALP activity and formation of calcium nodule. Western blotting and Real-time polymerase chain reaction results showed that the introduction of Se-HA into PAA could promoted the expression of osteogenic-related proteins and mRNA (integrin-binding sialoprotein, osteopontin, runt-related transcription factor 2 and Osterix) in BMSCs. A muscle defect at the back and a bone defect at the femoral condyle of New Zealand white rabbits were introduced for evaluating the enhancement of bone regeneration of PAA and PAA/Se-HA30 composites. The implantation of muscle tissue revealed good biocompatibility of PAA and PAA/Se-HA30 composites. The implantation of bone defect showed that PAA/Se-HA30 composites enhanced bone formation at the defect site (8 weeks), exhibiting good bone conductivity. Therefore, the PAA-based composite was a promising candidate material for bone tissue regeneration.

Injectable smart stimuli-responsive hydrogels: pioneering advancements in biomedical applications

Hydrogels have established their significance as prominent biomaterials within the realm of biomedical research. However, injectable hydrogels have garnered greater attention compared with their conventional counterparts due to their excellent minimally invasive nature and adaptive behavior post-injection. With the rapid advancement of emerging chemistry and deepened understanding of biological processes, contemporary injectable hydrogels have been endowed with an "intelligent" capacity to respond to various endogenous/exogenous stimuli (such as temperature, pH, light and magnetic field). This innovation has spearheaded revolutionary transformations across fields such as tissue engineering repair, controlled drug delivery, disease-responsive therapies, and beyond. In this review, we comprehensively expound upon the raw materials (including natural and synthetic materials) and injectable principles of these advanced hydrogels, concurrently providing a detailed discussion of the prevalent strategies for conferring stimulus responsiveness. Finally, we elucidate the latest applications of these injectable "smart" stimuli-responsive hydrogels in the biomedical domain, offering insights into their prospects.

A Comparative Study of Mesoporous Silica and Mesoporous Bioactive Glass Nanoparticles as Non-Viral MicroRNA Vectors for Osteogenesis

Micro-ribonucleic acid (miRNA)-based therapies show advantages for bone regeneration but need efficient intracellular delivery methods. Inorganic nanoparticles such as mesoporous bioactive glass nanoparticles (MBGN) and mesoporous silica nanoparticles (MSN) have received growing interest in the intracellular delivery of nucleic acids. This study explores the capacity of MBGN and MSN for delivering miRNA to bone marrow mesenchymal stem cells (BMSC) for bone regenerative purposes, with a focus on comparing the two in terms of cell viability, transfection efficiency, and osteogenic actions. Spherical MBGN and MSN with a particle size of ~200 nm and small-sized mesopores were prepared using the sol-gel method, and then the surface was modified with polyethyleneimine for miRNA loading and delivery. The results showed miRNA can be loaded into both nanoparticles within 2 h and was released sustainedly for up to 3 days. Confocal laser scanning microscopy and flow cytometry analysis indicated a high transfection efficiency (>64%) of both nanoparticles without statistical difference. Compared with MSN, MBGN showed stronger activation of alkaline phosphatase and activation of osteocalcin genes. This translated to a greater osteogenic effect of MBGN on BMSC, with Alizarin red staining showing greater mineralization compared with the MSN group. These findings show the potential for MBGN to be used in bone tissue engineering.

An injectable pH neutral bioactive glass-based bone cement with suitable bone regeneration ability

Background

As a class of promising bone augmentation materials, bone cements have attracted particular attention. Due to various limitations, the current bone cements are still imperfect. In this study, an injectable pH neutral bioactive bone cement (PSC/CSC) was developed by mixing phosphosilicate bioactive glass (PSC) and α-calcium sulfate hemihydrate (CSH), with the goal of optimizing bone defects repairs.

Methods

A range of compositions (PSC/CSC: 10P/90C, 30P/70C, 50P/50C) were developed and their physicochemical properties evaluated. Their bone regeneration ability was compared to those of two widely used bone cements as controls (calcium phosphate cement (CPC) and Genex®) in rabbit femoral condyle bone defect models for 4, 8 and 12 weeks. Based on physicochemical properties and in vivo bone regeneration ability, the PSC/CSC exhibited the best outcomes was selected. Then, in vitro, the effects of selected PSC/CSC, CPC and Genex® extracts on MC3T3-E1 cell proliferation, migration and osteogenesis as well as angiogenesis of HUVECs were examined.

Results

Based on physicochemical properties, the 30P/70C formula exhibited suitable operability and compressive strength (3.5 ± 0.3 MPa), which fulfilled the requirements for cancellous bone substitutes. In vivo, findings from micro-CT and histological analyses showed that the 30P/70C formula better promoted bone regeneration, compared to 10P/90C, 50P/50C, CPC and Genex®. Hence, 30P/70C was selected as the ideal PSC-based cement. In vitro, the 30P/70C extracts showed better promotion of cell viability, alkaline phosphatase (ALP) activity, calcium mineral deposition, mRNA and protein expression levels of osteogenesis in MC3T3-E1 cells, further supporting its superiority. Meanwhile, the 30P/70C extracts also showed better stimulation of HUVECs proliferation and angiogenesis.

Conclusion

The new composite cement, 30P/70C, is a favorable bioactive glass-based bone cement with suitable operability, compressive strength and bone regeneration ability.

The translational potential of this article

Clinically, treatment of large bone defects is still a major challenge for orthopaedic trauma. We showed that 30P/70C has the potential to be clinically used as an injectable cement for rapid bone repairs and reconstruction of critical sized bone defects.

Applications of Calcium-Based Nanomaterials in Osteoporosis Treatment

With rapidly aging populations worldwide, osteoporosis has become a serious global public health problem. Caused by disordered systemic bone remodeling, osteoporosis manifests as progressive loss of bone mass and microarchitectural deterioration of bone tissue, increasing the risk of fractures and eventually leading to osteoporotic fragility fractures. As fracture risk increases, antiosteoporosis treatments transition from nonpharmacological management to pharmacological intervention, and finally to the treatment of fragility fractures. Calcium-based nanomaterials (CBNMs) have unique advantages in osteoporosis treatment because of several characteristics including similarity to natural bone, excellent biocompatibility, easy preparation and functionalization, low pH-responsive disaggregation, and inherent pro-osteogenic properties. By combining additional ingredients, CBNMs can play multiple roles to construct antiosteoporotic biomaterials with different forms. This review covers recent advances in CBNMs for osteoporosis treatment. For ease of understanding, CBNMs for antiosteoporosis treatment can be classified as locally applied CBNMs, such as implant coatings and filling materials for osteoporotic bone regeneration, and systemically administered CBNMs for antiosteoporosis treatment. Locally applied CBNMs for osteoporotic bone regeneration develop faster than the systemically administered CBNMs, an important consideration given the serious outcomes of fragility fractures. Nevertheless, many innovations in construction strategies and preparation methods have been applied to build systemically administered CBNMs. Furthermore, with increasing interest in delaying osteoporosis progression and avoiding fragility fracture occurrence, research into systemic administration of CBNMs for antiosteoporosis treatment will have more development prospects. Deep understanding of the CBNM preparation process and optimizing CBNM properties will allow for increased application of CBNMs in osteoporosis treatments in the future.

Preparation of the bioglass/chitosan-alginate composite scaffolds with high bioactivity and mechanical properties as bone graft materials

Bioglass/chitosan-alginate (BCA) composite scaffolds with remarkable performance for bone tissue engineering are successfully prepared by freeze-drying method. The influence of the addition amount of sodium alginate (SA) on the microstructure, porosity, pore size, swelling ratio, degradation ratio, mechanical properties and mineralization ability of BCA composite scaffolds is studied and characterized by various techniques of the scanning electron microscopy, X-ray diffraction, infrared absorption spectrometer and so on. The results show that the BCA composite scaffolds have the three-dimensional interconnected network structure with the high porosity of 82%-87% and a suitable average pore size of 140-200 μm. With the increase of SA addition, the porosity and pore size of BCA gradually reduced and the thickness of pore wall increased. The swelling and degradation ratios decreased gradually with the raising SA and increased with the prolongation of soaking time in PBS. The mechanical strength of BCA was also significantly enhanced, and the mineralization ability of bioglass was effectively deployed with the adding SA of BCA. The improved performance of BCA may be attributed to the formed 3D network structure, activated bioavailability and crosslinking ability between chitosan and SA. It indicates that BCA composite scaffolds have potential applications in bone issues engineering.

Assessment of Collagen-Based Nanostructured Biomimetic Systems with a Co-Culture of Human Bone-Derived Cells

Osteoporosis is a worldwide disease resulting in the increase of bone fragility and enhanced fracture risk in adults. In the context of osteoporotic fractures, bone tissue engineering (BTE), i.e., the use of bone substitutes combining biomaterials, cells, and other factors, is considered a potential alternative to conventional treatments. Innovative scaffolds need to be tested in in vitro systems where the simultaneous presence of osteoblasts (OBs) and osteoclasts (OCs), the two main players of bone remodeling, is required to mimic their crosstalk and molecular cooperation. To this aim, two composite materials were developed, based on type I collagen, and containing either strontium-enriched mesoporous bioactive glasses or rod-like hydroxyapatite nanoparticles. The developed nanostructured systems underwent genipin chemical crosslinking and were then tested with an indirect co-culture of human trabecular bone-derived OBs and buffy coat-derived OC precursors, for 2–3 weeks. The favorable structural and biological properties of the materials proved to successfully support the viability, adhesion, and differentiation of cells, encouraging a further investigation of the developed bioactive systems as biomaterial inks for the 3D printing of more complex scaffolds for BTE.

A 3D printed Ga containing scaffold with both anti-infection and bone homeostasis-regulating properties for the treatment of infected bone defects

Large bone defects face a high risk of infection, which can also lead to bone homeostasis disorders. This seriously hinders the bone healing process; therefore, the help of a dual-functional scaffold that has both anti-infection and bone-homeostasis-regulating capacities is needed in the treatment of infected bone defects. In this study, a 3D printed dual-functional scaffold composed of poly-ε-caprolactone (PCL), mesoporous bioactive glasses (MBG), and gallium (Ga) was produced. In vitro experiments demonstrated the excellent antibacterial ability of the PCL/MBG/Ga scaffold against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). The scaffold also significantly inhibited osteoclastic activity and promoted osteogenic differentiation. Furthermore, a rabbit model with an infected bone defect in the radius was used to evaluate the in vivo bone healing capability of PCL/MBG/Ga. The results demonstrate that the PCL/MBG/Ga scaffold can significantly accelerate bone healing and prevent bone resorption, suggesting its potential for application in repairing infected bone defects.

Adipocyte-secreted microvesicle-derived miR-148a regulates adipogenic and osteogenic differentiation by targeting Wnt5a/Ror2 pathway

AIMS

Adipocyte-secreted microvesicles (MVs)-derived microRNAs (miRNAs) are relevant to adipogenic and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in osteonecrosis of the femoral head (ONFH). Our aims are to investigate the mechanism of adipocyte-derived MVs-miR-148a in ONFH.

MATERIALS AND METHODS

Adipocyte-derived MVs were identified via transmission electron microscopy and specific markers expression. The adipogenic and osteogenic differentiation were investigated by Oil-Red O staining, alkaline phosphatase (ALP) activity, Alizarin Red S (ARS) staining and osteogenic or adipogenic factors levels. Genes and proteins expression were detected by using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. The relationship between miR-148a and Wnt5a was tested via dual-luciferase reporter analysis. The adipogenic differentiation and osteogenic differentiation in methylprednisolone (MPS)-induced ONFH rat model were assessed via hematoxylin-eosin (HE) staining, and immunohistochemical staining of collagen I (COL I).

KEY FINDINGS

Adipocyte-derived MVs promoted adipogenic differentiation via increasing Oil-Red O staining positive cells, adiponectin (Adipoq), acid-binding protein 2 (aP2) and peroxisome proliferator-activated receptor γ (PPAR-γ) levels, and repressed osteogenic differentiation of BMSCs via decreasing ARS staining positive cells, ALP, Runt-related transcription factor 2 (RUNX2) and osteocalcin (OCN) levels. MiR-148a was present in adipocyte-derived MVs, and miR-148a knockdown inhibited adipogenic differentiation and promoted osteogenic differentiation. Furthermore, Wnt5a expression was regulated by miR-148a. MiR-148a overexpression facilitated adipogenic differentiation and suppressed osteogenic differentiation via regulating the Wnt5a/Ror2 pathway. Adipocyte-derived MVs promoted adipogenic differentiation and inhibited osteogenic differentiation in MPS-induced ONFH rat model.

SIGNIFICANCE

Adipocyte-derived MVs-miR-148a promoted adipogenic differentiation and suppressed osteogenic differentiation via targeting the Wnt5a/Ror2 pathway.

Mesoporous Bioactive Glasses Cytocompatibility Assessment: A Review of In Vitro Studies

Thanks to their high porosity and surface area, mesoporous bioactive glasses (MBGs) have gained significant interest in the field of medical applications, in particular, with regards to enhanced bioactive properties which facilitate bone regeneration. The aim of this article is to review the state of the art regarding the biocompatibility evaluation of MBGs and provide a discussion of the various approaches taken. The research was performed using PubMed database and covered articles published in the last five years. From a total of 91 articles, 63 were selected after analyzing them according to our inclusion and exclusion criteria. In vitro methodologies and techniques used for biocompatibility assessment were investigated. Among the biocompatibility assessment techniques, scanning electron microscopy (SEM) has been widely used to study cell morphology and adhesion. Viability and proliferation were assessed using different assays including cell counting and/or cell metabolic activity measurement. Finally, cell differentiation tests relied on the alkaline phosphatase assay; however, these were often complemented by specific bimolecular tests according to the exact application of the mesoporous bioactive glass. The standardization and validation of all tests performed for MBG cytocompatibility is a key aspect and crucial point and should be considered in order to avoid inconsistencies, bias between studies, and unnecessary consumption of time. Therefore, introducing standard tests would serve an important role in the future assessment and development of MBG materials.

Nanocomposite scaffolds for accelerating chronic wound healing by enhancing angiogenesis

Skin is the body's first barrier against external pathogens that maintains the homeostasis of the body. Any serious damage to the skin could have an impact on human health and quality of life. Tissue engineering aims to improve the quality of damaged tissue regeneration. One of the most effective treatments for skin tissue regeneration is to improve angiogenesis during the healing period. Over the last decade, there has been an impressive growth of new potential applications for nanobiomaterials in tissue engineering. Various approaches have been developed to improve the rate and quality of the healing process using angiogenic nanomaterials. In this review, we focused on molecular mechanisms and key factors in angiogenesis, the role of nanobiomaterials in angiogenesis, and scaffold-based tissue engineering approaches for accelerated wound healing based on improved angiogenesis.

High phosphate content in bioactive glasses promotes osteogenesis in vitro and in vivo

OBJECTIVES

High phosphate content was found to significantly increase apatite formation of bioactive glasses (BGs) in vitro. However, there is very limited understanding of the effect of phosphate contents on osteogenesis which is important for clinical applications. The aims of this study were to investigate how phosphate content influences apatite formation ability of bioactive glasses in α-MEM culture medium and whether high phosphate content in bioactive glasses promotes osteogenesis in vitro and in vivo.

METHODS

Four phosphate containing bioactive glasses were synthesized via a melt-quench method and characterized using X-ray powder Diffraction (XRD), TGA-DSC and Fourier transform infra-red spectroscopy (FTIR). The apatite formation ability in α-MEM culture medium and the in vitro and in vivo osteogenic potential of these bioactive glass were explored.

RESULTS

FTIR spectra confirmed faster apatite formation with an increase in phosphate content. The culture media containing ions released from the BGs showed enhanced cell viability and alkaline phosphatase activity of osteoblasts. Osteoblasts cultured with extracted BGs culture media generally showed increased proliferation, mineralized nodule formation, osteogenic and angiogenic genes expression with an increase in phosphate content in the glass compositions. An in vivo study demonstrated a larger amount of new bone formation in the calvarial defects implanted with high phosphate containing BG granules compared with that of BG without the presence of phosphate at 8 weeks post-surgery.

SIGNIFICANT

The presence of higher phosphate content accelerates apatite formation and promotes osteogenesis, indicating that both apatite formation and osteogenesis of bioactive glasses can be tailored by varying phosphate content for specific clinical needs and personalized treatments.

Enhanced osteogenesis and therapy of osteoporosis using simvastatin loaded hybrid system

Postmenopausal osteoporosis is a common chronic dynamic bone disorder, caused by estrogen deficiency. To address this issue, we constructed a controlled drug-release system composed of poly (N-isopropylacrylamide) brush modified mesoporous hydroxyapatite (MHA-SIM-P) loaded with simvastatin (SIM) using an ovariectomised (OVX) rat model. Quantitative alkaline phosphatase activity assay, alizarin red staining and RT-PCR were tested to evaluate the osteogenic ability in vitro. The results showed that the MHA-SIM-P nanoparticles significantly improved the osteogenic differentiation of OVX bone marrow stromal cells (BMSCs) in vitro. In osteoporotic animal model, the therapeutic efficiency for bone defect was evaluated by μCT analysis, tartrate-resistant acid phosphatase, haematoxylin and eosin staining, which showed improved bone formation and less osteoclastic response in OVX rats after surgery for 3 and 6 weeks. This polymer brush modified MHA system provided a sustained release system of hydrophobic SIM to inhibit osteoporosis together with MHA nanoparticle promoting the osteogenesis. Thus, this novel strategy exhibited great potential for promoting osteogenic ability and treating local osteoporotic defects.

Simultaneously promoting adhesion and osteogenic differentiation of bone marrow-derived mesenchymal cells by a functional electrospun scaffold

Electrospinning is a common technology to construct tissue engineering scaffolds for bone regeneration. However, pure electrospun scaffolds do not enrich seed cells or promote their osteogenic differentiation. Biological functionalization of tissue engineering scaffolds is currently a hot research topic. Therefore, in this study, the bone marrow-derived mesenchymal cells (BM-MSC)-specific affinity peptide E7 and a bone morphogenic protein 2 (BMP-2) mimetic peptide were concomitantly conjugated onto the surface of an electrospun scaffold to construct a functional PEB scaffold. Characterization of PEB scaffolds revealed that both E7 and BMP-2 mimetic peptides were successfully conjugated onto the surface of electrospun scaffolds. With regard to biological activity, the PEB scaffold could synchronously promote adhesion and osteogenic differentiation of BM-MSC as a result of the co-delivery of E7 and BMP-2 mimetic peptides, which proved superior compared with the other three scaffolds. Consequently, the PEB scaffold offers a new concept for the construction of bone tissue engineering scaffolds.

Bioactive glass containing 90% SiO2 in hard tissue engineering: An in vitro and in vivo characterization study

Bioactive glass has been proved to have many applications in bioengineering due to its bone regenerative properties. In this work, an innovative, highly resorbable bioactive glass containing 90% SiO₂ (BG90) to be used as a bone substitute was developed. The BG90 was synthetized by the sol-gel process with the dry step at room temperature. The biomaterial showed in vitro and in vivo bioactivities even with silica content up to 90%. Moreover, the BG90 presented high porosity and surface area due to its homogenously interconnected porous network. In vitro, it was observed to have high cell viability and marked osteoblastic differentiation of rat bone marrow-derived cells when in contact with BG90 ion extracts. The BG90 transplantation into rat tibia defects was analysed at 1, 2, 3, 4, 7, and 10 weeks post-operatively and compared with the defects of negative (no graft) and positive (autogenous bone graft) controls. After 4 weeks of grafting, the BG90 was totally resorbed and induced higher bone formation than did the positive control. Bone morphogenetic protein 2 (BMP-2) expression at the grafting site peaked at 1 week and decreased similarly after 7 weeks for all groups. Only the BG90 group was still exhibiting BMP-2 expression in the last experimental time. Our data demonstrated that the BG90 could be an attractive candidate to provide useful approaches in hard-tissue bioengineering.

Evaluation of BMP-2 Enhances the Osteoblast Differentiation of Human Amnion Mesenchymal Stem Cells Seeded on Nano-Hydroxyapatite/Collagen/Poly(l-Lactide)

Background: The aim of this study is to evaluate the effects of recombinant human bone morphogenetic protein 2 (rhBMP-2), human amnion mesenchymal stem cells (hAMSCs), and nanohydroxyapatite/collagen/poly(l-lactide) (nHAC/PLA) in tissue engineering to provide potential approaches for periodontal bone regeneration. Methods: hAMSCs were isolated from discarded amniotic membrane samples and cultured in vitro. Alkaline phosphatase (ALP) staining and alizarin red staining were performed to evaluate the osteoblast (OB) differentiation ability of hAMSCs. Three groups were divided: the experimental group (cells transfected with pcDNA3.1-rhBMP-2), the blank group (cells without gene transfection), and the control group (cells transfected with empty plasmid). RT-PCR and western blot were used to examine whether rhBMP-2 has been successfully expressed. 3-(4,5)-dimethylthiahiazol(-z-y1)-3,5-di-phenytetrazo-liumromide assay (MTT) was done to detect the effect of rhBMP-2 on hAMSCs seeded on nHAC/PLA. ALP activity, mineral formation assay, calcium, phosphate and osteocalcin (OCN) content, and OCN and RUNX2 expression of hAMSCs were detected to evaluate osteogenic differentiation capability of rhBMP-2 on hAMSCs seeded on nHAC/PLA. Results: hAMSCs exhibited intense ALP staining, obvious calcium deposition, and mineralization nodules, and rhBMP-2 were highly expressed in the experimental group. The proliferation of the hAMSCs with rhBMP-2 on nHAC/PLA was significantly higher than the cells without rhBMP-2, and the cells all increased in a time-dependent manner. rhBMP-2 significantly increased the OCN and phosphate content, mineral formation, ALP activity, osteogenic biomarkers OCN, and Runx2, and decreased calcium content in hAMSCs seeded on the nHAC/PLA scaffold. Conclusions: This finding demonstrated that hAMSCs has an ideal OB differentiation ability. rhBMP-2 facilitates the proliferation and osteogenesis of hAMSCs. The nHAC/PLA could act as a good scaffold for hAMSCs seeding, proliferation, and osteogenic differentiation. The application of rhBMP-2, nHAC/PLA, and hAMSCs in tissue engineering may offer promising possibilities for periodontal bone regeneration.

The higher osteoprotective activity of psoralidin in vivo than coumestrol is attributed by its presence of an isopentenyl group and through activated PI3K/Akt axis

Prenylation of bioactive natural compounds has been postulated to be able to enhance the utilization rate and affinity of the compounds with cell membranes, thus promote their bioactivities. Coumestrol, isolated from Medicago sativa, has been known as a phytoestrogen which has bone health benefits. In our previous work, psoralidin, a prenylated coumestrol, was proved to have a higher ability than coumestrol to promote bone formation and to attenuate resorption in vitro. However, it remains to be investigated whether psoralidin will have stronger bone health benefits than coumestrol. In the current study, psoralidin was isolated from Psoralea corylifolia L. and the osteotropic activities of coumestrol and psoralidin were compared in ovariectomized (OVX) rats. Both coumestrol and psoralidin were found to suppress OVX-induced bone loss in vivo, as shown by improved total bone mineral content (t-BMC) or density (t-BMD) and mineral apposition rate, bone biomechanical properties, microstructure and trabecular bone formation, enhanced osteogenic differentiation but suppressed adipogenic differentiation of bone marrow stromal cells (BMSCs), and activation of PI3K/Akt axis and downstream factors such as GSK3β/β-catenin and Nrf-2/HO-1. However, psoralidin was shown to have higher activities than coumestrol in the above measurements/indices. Our findings demonstrate that psoralidin, as a novel anti-osteoporosis candidate, could suppress bone loss in OVX rats and have better osteoprotective effects than coumestrol, which may be related to the presence of the isopentenyl group in psoralidin.

The synergistic effects of Sr and Si bioactive ions on osteogenesis, osteoclastogenesis and angiogenesis for osteoporotic bone regeneration

Bioactive ions released from bioceramics play important roles in bone regeneration; however, it is unclear how each ionic composition in complex bioceramics exerts its specific effect on bone regeneration. The aim of this study is to elucidate the functional effects of Sr and Si ions in bioceramics on the regeneration of osteoporotic bone. A model bioceramic with Sr- and Si-containing components (SMS) was successfully fabricated and the effects of ionic products from SMS bioceramics on the osteogenic, osteoclastic and angiogenic differentiation of rBMSCs-OVX and RANKL-induced osteoclasts were investigated. The results showed that SMS bioceramics could enhance ALP activity and expression of Col 1, OCN, Runx2, and angiogenic factors including VEGF and Ang-1. SMS bioceramics not only rebalanced the OPG/RANKL ratio of rBMSCs-OVX at early stage, but also repressed RANKL-induced osteoclast formation and expression of TRAP, DC-STAMP, V-ATPase a3, and NFATc1. The synergistic effects of Sr and Si ions were further investigated as compared with those of similar concentrations of Sr and Si ions alone. Sr and Si ions possessed synergistic effects on osteogenesis, osteoclastogenesis, and angiogenesis, attributed to the dominant effects of Sr ions on enhancing angiogenesis and repressing osteoclastogenesis, and the dominant effects of Si ions on stimulating osteogenesis. The in vivo study using critical-size mandibular defects of OVX rat models showed that SMS bioceramics could significantly enhance bone formation and mineralization compared with β-TCP bioceramics. Our results are the first to elucidate the specific effect of each ion from bioceramics on osteogenesis, osteoclastogenesis and angiogenesis for osteoporotic bone regeneration, paving the way for the design of functional biomaterials with complex compositions for tissue engineering and regenerative medicine.

STATEMENT OF SIGNIFICANCE

Bioactive ions released from bioceramics play important roles for bone regeneration; however, it is unclear how each of ionic compositions in complex bioceramics exerts its specific effect on bone regeneration. The aim of present study is to elucidate the functional effects of Sr and Si ions in complex bioceramics on the regeneration of osteoporotic bone. A model bioceramic with Sr and Si-containing components (SMS) was successfully fabricated and the effects of ionic products from SMS bioceramics on the osteogenic, osteoclastic and angiogenic differentiation of rBMSCs-OVX and RANKL-induced osteoclasts were investigated. The results showed that SMS bioceramics could enhance ALP activity and expression of Col 1, OCN, Runx2 and angiogenic factors including VEGF and Ang-1. SMS bioceramics not only rebalanced the ratio of OPG/RANKL of OVX-BMSCs at early stage, but also repressed RANKL-induced osteoclast formation and expression of TRAP, DC-STAMP, V-ATPase a3, and NFATc1. The synergistic effects of Sr and Si ions were further investigated as compared with the similar concentration of Sr and Si ions alone. It was found that Sr and Si ions possessed synergistic effects on osteogenesis, osteoclastogenesis and angiogenesis, attributed to the dominant effects of Sr ions on enhancing angiogenesis and repressing osteoclastogenesis, and the dominant effects of Si ions on stimulating osteogenesis. The in vivo study using critical-size mandibular defects of OVX rat models showed that SMS bioceramics could significantly enhance bone formation and mineralization as compared with β-TCP bioceramics. It is suggested that SMS bioceramics may be a promising biomaterial for osteoporotic bone regeneration. To our knowledge, this is the first time to elucidate the specific effect of each ion from bioceramics on osteogenesis, osteoclastogenesis and angiogenesis for osteoporotic bone regeneration, paving the way to design functional biomaterials with complex compositions for tissue engineering and regenerative medicine.

Bio-inspired bioactive glasses for efficient microRNA and drug delivery

Bio-inspired pinecone-like bioactive glasses consisting of ordered thin-layers separated by consistent cavities were synthesized using a sol-gel process. The short diameter of the as-produced particles was as short as 161 nm, and the surface area was as high as 280 m² g^-1. The pore volume, ranging from ∼0.74 cm³ g^-1 to ∼0.67 cm³ g^-1, could be modulated by the aqueous ammonia concentration. The surface was further tailored for positive charges by amino grafting. The as-produced nanoparticles could successfully enter cells via endocytosis. The microRNA delivery of the bioactive glass particles was further investigated by fluorescence microscopy and flow cytometry, indicating a loading efficiency and transfection efficiency greater than 90%. The potential of such particles as drug carriers was also studied. CCK8, live-dead cell staining and PI/annexinV double staining analyses confirmed that the bioactive glass particles loaded with antitumour doxorubicin (DOX) significantly accelerated the apoptosis of tumour cells. These bio-inspired bioactive glasses are promising as novel vectors for drug and microRNA delivery with high efficiency.

Effects of rhBMP-2 gene transfection to periodontal ligament cells on osteogenesis

The present study aims to investigate the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on the osteogenesis of periodontal ligament (PDL) cells. The expression vector of rhBMP-2 (pcDNA3.1-rhBMP-2) was established. PDL cells were obtained through the enzymatic digestion and tissue explant methods and verified by immunohistochemistry. Cells were classified into experimental (cells transfected with pcDNA3.1/rhBMP-2-EGFP), blank (cells with no transfection) and control group (cells transfected with empty plasmid). rhBMP-2 expression was assessed via Western blotting analysis. The mineralization ability, alkaline phosphatase (ALP) activity and level of related osteogenic biomarkers were detected to evaluate the osteogenic characteristics of PDL cells. The rhBMP-2 expression vector (pcDNA3.1-rhBMP-2) was successfully established. Primary PDL cells displayed a star or long, spindle shape. The cultured cells were long, spindle-shaped, had a plump cell body and homogeneous cytoplasm and the ellipse nucleus contained two or three nucleoli. Cells displayed a radial, sheaf-like or eddy-like arrangement after adherence growth. Immunohistochemical staining confirmed that cells originated from mesenchymal opposed to epithelium. The experimental group exhibited an enhanced mineralization ability, higher ALP activity and increased expression of rhBMP-2 and osteogenic biomarkers (Runx2, collagen type I and osteocalcin) than the blank and control group. The present study demonstrated that rhBMP-2 transfection enhances the osteogenesis of PDL cells and provides a possibility for the application of rhBMP-2 expression products in dental disease treatment.