Osteoinductive Activity Research Articles

Comparison of a Novel Modified PLA/HA Bioabsorbable Interference Screw With Conventional PLGA/β-TCP Screw: Effect on 1-Year Postoperative Tibial Tunnel Widening in a Canine ACLR Model.

Tibial bone tunnel widening (TW) is a common postoperative phenomenon after anterior cruciate ligament reconstruction (ACLR). To compare the physical, biomechanical, osteoinductive, and histological characteristics of 2 fabricated bioabsorbable interference screws: (1) a modified poly(l-lactide-co-d, l-lactide) and hydroxyapatite (mPLA/HA) screw and (2) a poly(l-lactide-co-glycolide) and β-tricalcium phosphate (PLGA/β-TCP) screw; and to evaluate the effect of the PLA/HA screw on ameliorating postoperative TW in a canine ACLR model. Controlled laboratory study. In vitro, the physical and biomechanical properties of the mPLA/HA and PLGA/β-TCP screws were tested. The osteoinductive activity of the screws was studied by cell experiments. In vivo, ACLR was performed on 48 beagle dogs, divided into the mPLA/HA group and the PLGA/β-TCP group. The femoral and tibial ends of the graft were both fixed with screws. Six animals in each group were sacrificed after live computed tomography (CT) scanning at 1, 3, 6, and 12 months postoperatively. For six knee samples of each group, three knee samples underwent biomechanical testing, and 1 of them, along with the other 3 samples, underwent micro-CT and histological examination to evaluate tibial TW. The mPLA/HA screw exhibited better particle dispersion, bending strength, desirable self-locking effect, and optimized degradation behavior both in vivo and in vitro. Histologically, the mPLA/HA screw had comparative osteoinductive activity. There was good screw-bone integration using the mPLA/HA screw, while most fibrous scar healing was in the PLGA/β-TCP group. There were significant differences between the mPLA/HA and PLGA/β-TCP groups in tibial bone tunnel diameter at the screw body (6 months postoperatively: 5.09 ± 0.44 vs 7.12 ± 0.67; 12 months postoperatively: 4.83 ± 0.27 vs 6.23 ± 0.56; P < .01 for both) and the screw tail (6 months postoperatively: 4.84 ± 0.28 vs 5.97 ± 0.73; 12 months postoperatively: 4.77 ± 0.29 vs 5.92 ± 0.56; P < .01 for both). Compared with the PLGA/β-TCP screw commonly used in clinics at present, the mPLA/HA screw had comparative biosafety and mechanical properties, satisfactory biomechanical properties, and osteoinductive activity in vivo and in vitro. It effectively ameliorated the postoperative tibial TW in a canine ACLR model and increased the quality of screw-bone integration. The good mechanical and biological properties of the mPLA/HA screws may provide an option to reduce the incidence of complications after ACLR.

Osteogenic and osteoclastic differentiation by control release of adenosine within PEI/HA/Collagen composite coatings

In virtue of the rapid metabolism and short half-life of adenosine (AD) in the human body, it is highly desired to explore new adenosine delivery system with controlled and steady release capacity. In this study, composite coatings consisting of polyethyleneimine (PEI), hyaluronic acid (HA) and collagen type I (COL-1) on titanium substrate surface are developed by layer-by-layer self-assembly technique, in which different concentrations of AD are encapsulated. In-vitro release study demonstrated a steady and sustained release of AD from the composite coating system. Adenosine within composite coatings depicted a concentration-dependent regulatory effect on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and osteoclastic differentiation of mouse leukemia cells of monocyte macrophage (RAW264.7) cells. All of these coatings exhibited good cell viability and promoted osteoblast cell proliferation. Among various composite coatings, the optimized coating specimen with loading of 65 μg AD (AD2) exhibits the best osteoconductive and osteoinductive activities with significantly enhanced osteoblast-associated gene expressions, and increased alkaline phosphatase (ALP) activity and calcium deposits. On the other hand, AD2 specimen shows the activity of inhibiting osteoclast differentiation and osteobclast-associated gene expressions as well as suppressing tartrate-resistant acid phosphatase (TRAP) activity. The superior performance of AD/PEI/HA/COL composite coatings indicated that this coating system could be useful for bone tissue engineering.

Incorporation of carboxymethyl chitosan (CMCS) for the modulation of physio-chemical characteristics and cell proliferation environment of the composite hydrogel microspheres

Hydrogels have excellent swelling properties and have been widely applied in tissue engineering because of their similarity to the extracellular matrix (ECM). Sodium alginate (SA) and carboxymethyl chitosan (CMCS) were prepared into hydrogel microspheres with Ca2+crosslinking in our study. The morphology, inner structure, mechanical properties, water content, swelling rate and BMP-2 loading and releasing properties were characterized. Our results showed that the composite SA /CMCS hydrogel microspheres were translucent and spherical in shape with uniform particle size. The incorporation of CMCS further increased the diameters of the microspheres, internal pore structure, water content, and mechanical properties of the SA/CMCS hydrogel microspheres. At the same SA concentration, with the increase of CMSC concentration, the diameter of microspheres could be increased by about 0.4 mm, the water content can be increased about 1%-2%. As for the mechanical properties, the compressive strength can be increased by 0.04-0.1 MPa, and the modulus of elasticity can be increased by 0.1-0.15 MPa. BMP-2 was chosen as a model agent and it could be loaded into SA/CMCS microspheres, and the incorporation of CMCS increased BMP-2 loading. The encapsulated BMP-2 was sustainably releasedin vitro. The leaching solutions of the SA/CMCS hydrogel microspheres exhibited good cytocompatibility and could increase ALP activity, ALP expression, and biomineralization on MC3T3-E1 cells. After 7 d of co-culture, ALP activities in S2.5C2 and S2.5C3 groups was increased by 50% and 45% compared with that of the control group. When embedded in the SA/CMCS microspheres, the MC3T3-E1 cells were evenly distributed inside the hydrogel microspheres and remained viable. Transcriptomic studies showed that incorporation of CMCS induced upregulation of 1141 differentially expressed genes (DEGs) and downregulation of 1614 DEGs compared with SA microspheres. The most significantly enriched pathways were the Wnt and MAPK signaling pathways induced by the incorporation of CMCS and BMP-2. In conclusion, our results indicated that the physiochemical characteristics of the SA hydrogel microspheres could be greatly modulated by CMCS to better mimic the ECM microenvironment and induce osteo-inductive activities of MC3T3-E1 cells.

Multifunctional Bone Regeneration Membrane with Flexibility, Electrical Stimulation Activity and Osteoinductive Activity.

The use of membrane-based guided bone regeneration techniques has great potential for single-stage reconstruction of critical-sized bone defects. Here, a multifunctional bone regeneration membrane combining flexible elasticity, electrical stimulation (ES) and osteoinductive activity is developed by in situ doping of MXene 2D nanomaterials with conductive functionality and β-TCP particles into a Poly(lactic acid-carbonate (PDT) composite nano-absorbable membrane (P/T/MXene) via electrostatic spinning technique. The composite membrane has good feasibility due to its temperature sensitivity, elastic memory capacity, coordinated degradation profile and easy preparation process. In vitro experiments showed the P/T/MXene membrane effectively promoted the recruitment and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) under ES and enhanced the angiogenic capacity of endothelial cells, which synergistically promoted bone regeneration through neovascularization. In addition, an in vivo rat model of cranial bone defects further confirmed the bone regeneration efficacy of the P/T/MXene membrane. In conclusion, the developed P/T/MXene membrane can effectively promote bone regeneration through their synergistic multifunctional effects, suggesting the membranes have great potential for guiding tissue regeneration and providing guidance for the biomaterials design.

PLGA/β-TCP/ICT composite scaffold incorporating MXene (Ti3C2Tx) promotes osteogenesis through near-infrared-mediated mild photothermal therapy

Porous poly (lactic-co-glycolic acid)/β-tricalcium phosphate icaritin (PTI) scaffold is an ideal alternative for repairing bone defects, but their osteoinductive activity are limited. In this study, we fabricated a MXene (Ti3C2Tx) composite PTI (TPTI) scaffold and evaluated its characterization. We co-cultured the scaffolds with rat bone marrow mesenchymal stem cells to access the biocompatibility and osteogenic potential of the TPTI scaffold under on-demand near-infrared (NIR) irradiation. Then TPTI scaffold was implanted in a femoral condyle defect model to evaluate the osteogenic properties by micro-computed tomography, histological and immunohistochemical analysis. The results of experiments reveal that MPTI scaffold has appropriate spatial structure, suitable mechanical strength, and superior photothermal properties. It can maintain the temperature at 42.0 ± 0.5 °C and promote the release of ICT from scaffold under 0.85 W cm−2 NIR irradiation. Furthermore, the scaffold is biocompatible and could promote cell proliferation, osteogenic differentiation, and biomineralization in vitro, as well as the repair of bone defects in vivo, and its effect is further enhanced under NIR irradiation. In conclusion, the MPTI scaffold has the potential to be applied in bone defects repairing, and its osteogenic property can be promoted under NIR irradiation through mild photothermal therapy.

3D Printed Pedicle Screws with Microarc Oxidation Ceramic Interfaces Enhance Osteointegration and Orthopedic Fixation Feasibility.

Effective osteointegration is of great importance for pedicle screws in spinal fusion surgeries. However, the lack of osteoinductive activity of current screws diminishes their feasibility for osteointegration and fixation, making screw loosening a common complication worldwide. In this study, Ti-6Al-4V pedicle screws with full through-hole design were fabricated via selective laser melting (SLM) 3D printing and then deposited with porous oxide coatings by microarc oxidation (MAO). The porous surface morphology of the oxide coating and the release of bioactive ions could effectively support cell adhesion, migration, vascularization, and osteogenesis in vitro. Furthermore, an in vivo goat model demonstrated the efficacy of modified screws in improving bone maturation and osseointegration, thus providing a promising method for feasible orthopedic internal fixation.

Piezoelectric stimulation enhances bone regeneration in alveolar bone defects through metabolic reprogramming of macrophages

AbstractImmunomodulation has emerged as a promising strategy for promoting bone regeneration. However, designing osteoimmunomodulatory biomaterial that can respond to mechanical stress in the unique microenvironment of alveolar bone under continuous occlusal stress remains a significant challenge. Herein, a wireless piezoelectric stimulation system, namely, piezoelectric hydrogel incorporating BaTiO3 nanoparticles (BTO NPs), is successfully developed to generate piezoelectric potentials for modulating macrophage reprogramming. The piezoelectric stimulation reprograms macrophages towards the M2 phenotype, which subsequently induces osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). RNA sequencing analysis reveals that piezoelectricity‐modulated macrophage M2 polarization is closely associated with metabolic reprogramming, including increased amino acid biosynthesis and fatty acid oxidation. The composite hydrogel with excellent biocompatibility exhibits immunomodulatory and osteoinductive activities. In a rat model of alveolar bone defects, the piezoelectric hydrogel effectively promotes endogenous bone regeneration at the load‐bearing sites. The piezoelectric‐driven osteoimmunomodulation proposed in this study not only broadens understanding of the mechanism underlying piezoelectric biomaterials for tissue regeneration but also provides new insights into the design and development of next‐generation immunomodulatory biomaterials.

Injectable and high-strength PLGA/CPC loaded ALN/MgO bone cement for bone regeneration by facilitating osteogenesis and inhibiting osteoclastogenesis in osteoporotic bone defects

Osteoporosis (OP) can result in slower bone regeneration than the normal condition due to the imbalance between osteogenesis and osteoclastogenesis, making osteoporotic bone defects healing a significant clinical challenge. Calcium phosphate cement (CPC) is a promising bone substitute material due to its good osteoinductive activity, however, the drawbacks such as fragility, slow degradation rate and incapability to control bone loss restrict its application in osteoporotic bone defects treatment. Currently, we developed the PLGA electrospun nanofiber sheets to carry alendronate (ALN) and magnesium oxide nanoparticle (nMgO) into CPC, therefore, to obtain a high-strength bone cement (C/AM-PL/C). The C/AM-PL/C bone cement had high mechanical strength, anti-washout ability, good injection performance and drug sustained release capacity. More importantly, the C/AM-PL/C cement promoted the osteogenic differentiation of bone marrow mesenchymal stem cells and neovascularization via the release of Mg2+ (from nMgO) and Ca2+ (during the degradation of CPC), and inhibited osteoclastogenesis via the release of ALN in vitro. Moreover, the injection of C/AM-PL/C cement significantly improved bone healing in an OP model with femur condyle defects in vivo. Altogether, the injectable C/AM-PL/C cement could facilitate osteoporotic bone regeneration, demonstrating its capacity as a promising candidate for treatment of osteoporotic bone defects.

Multifunctional Composite Scaffold with Nanosilver, Graphene Oxide, and Macrophage Membrane Vesicles for Sequential Treatment of Infected Bone Defects.

The management of infected bone defects poses a significant clinical challenge, and current treatment modalities exhibit various limitations. This study focuses on the development of a multifunctional composite scaffold comprising nanohydroxyapatite/polyethyleneglycol diacrylate matrix, silver nanoparticles, graphene oxide (GO), sodium alginate, and M2-type macrophage membrane vesicles (MVs) to enhance the healing of infected bone defects. The composite scaffold demonstrates several key features: first, it releases sufficient quantities of silver ions to effectively eliminate bacteria; second, the controlled release of MVs leads to a notable increase in M2-type macrophages, thereby significantly mitigating the inflammatory response. Additionally, GO acts synergistically with nanohydroxyapatite to enhance osteoinductive activity, thereby fostering bone regeneration. Through meticulous in vitro and in vivo investigations, the composite scaffold exhibits broad-spectrum antimicrobial effects, robust immunomodulatory capabilities, and enhanced osteoinductive activity. This multifaceted composite scaffold presents a promising approach for the sequential treatment of infected bone defects, addressing the antimicrobial, immunomodulatory, and osteogenic aspects. This study introduces innovative perspectives and offers new and effective treatment alternatives for managing infected bone defects.

A Biomimetic Multifunctional Scaffold for Infectious Vertical Bone Augmentation.

The regenerative treatment of infectious vertical bone defects remains difficult and challenging today. Current clinical treatments are limited in their ability to control bacteria and infection, which is unfavorable for new bone formation and calls for a new type of material with excellent osteogenic and antibacterial properties. Here a multifunctional scaffold is synthesized that mimics natural bone nanostructures by incorporating silver nanowiresinto a hierarchical, intrafibrillar mineralized collagen matrix (IMC/AgNWs), to achieve the therapeutic goals of inhibiting bacterial activity and promoting infectious alveolar bone augmentation in rats and beagle dogs. An appropriate concentration of 0.5mgmL-1 AgNWs is selected to balance biocompatibility and antibacterial properties. The achieved IMC/AgNWs exhibit a broad spectrum of antimicrobial properties against Gram-negative Porphyromonas gingivalis and Gram-positive Streptococcus mutans. When the IMC/AgNWs are cocultured with periodontal ligament stem cells, it possesses excellent osteoinductive activities under both non-inflammatory and inflammatory conditions. By constructing a rat mandibular infected periodontal defect model, the IMC/AgNWs achieve a near-complete healing through the canonical BMP/Smad signaling. Moreover, the IMC/AgNWs enhance vertical bone height and osseointegration in peri-implantitis in beagle dogs, indicating the clinical translational potential of IMC/AgNWs for infectious vertical bone augmentation.

Regulating the bioactivity of non-glycosylated recombinant human bone morphogenetic protein-2 to enhance bone regeneration

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is the predominant growth factor that effectively induces osteogenic differentiation in orthopedic procedures. However, the bioactivity and stability of rhBMP-2 are intrinsically associated with its sequence, structure, and storage conditions. In this study, we successfully determined the amino acid sequence and protein secondary structure model of non-glycosylated rhBMP-2 expressed by an E. coli expression system through X-ray crystal structure analysis. Furthermore, we observed that acidic storage conditions enhanced the proliferative and osteoinductive activity of rhBMP-2. Although the osteogenic activity of non-glycosylated rhBMP-2 is relatively weaker compared to glycosylated rhBMP-2; however, this discrepancy can be mitigated by incorporating exogenous chaperone molecules. Overall, such information is crucial for rationalizing the design of stabilization methods and enhancing the bioactivity of rhBMP-2, which may also be applicable to other growth factors.

Tailored apoptotic vesicles promote bone regeneration by releasing the osteoinductive brake

Accumulating evidence has demonstrated that apoptotic vesicles (apoVs) derived from mesenchymal stem cells (MSCs; MSC-apoVs) are vital for bone regeneration, and possess superior capabilities compared to MSCs and other extracellular vesicles derived from MSCs (such as exosomes). The osteoinductive effect of MSC-apoVs is attributed to their diverse contents, especially enriched proteins or microRNAs (miRNAs). To optimize their osteoinduction activity, it is necessary to determine the unique cargo profiles of MSC-apoVs. We previously established the protein landscape and identified proteins specific to MSC-apoVs. However, the features and functions of miRNAs enriched in MSC-apoVs are unclear. In this study, we compared MSCs, MSC-apoVs, and MSC-exosomes from two types of MSC. We generated a map of miRNAs specific to MSC-apoVs and identified seven miRNAs specifically enriched in MSC-apoVs compared to MSCs and MSC-exosomes, which we classified as apoV-specific miRNAs. Among these seven specific miRNAs, hsa-miR-4485-3p was the most abundant and stable. Next, we explored its function in apoV-mediated osteoinduction. Unexpectedly, hsa-miR-4485-3p enriched in MSC-apoVs inhibited osteogenesis and promoted adipogenesis by targeting the AKT pathway. Tailored apoVs with downregulated hsa-miR-4485-3p exhibited a greater effect on bone regeneration than control apoVs. Like releasing the brake, we acquired more powerful osteoinductive apoVs. In summary, we identified the miRNA cargos, including miRNAs specific to MSC-apoVs, and generated tailored apoVs with high osteoinduction activity, which is promising in apoV-based therapies for bone regeneration.

Injectable, anti-collapse, adhesive, plastic and bioactive bone graft substitute promotes bone regeneration by moderating oxidative stress in osteoporotic bone defect

The treatment of osteoporotic bone defect remains a big clinical challenge because osteoporosis (OP) is associated with oxidative stress and high levels of reactive oxygen species (ROS), a condition detrimental for bone formation. Anti-oxidative nanomaterials such as selenium nanoparticles (SeNPs) have positive effect on osteogenesis owing to their pleiotropic pharmacological activity which can exert anti-oxidative stress functions to prevent bone loss and facilitate bone regeneration in OP. In the current study a strategy of one-pot method by introducing Poly (lactic acid-carbonate) (PDT) and β-Tricalcium Phosphate (β-TCP) with SeNPs, is developed to prepare an injectable, anti-collapse, shape-adaptive and adhesive bone graft substitute material (PDT-TCP-SE). The PDT-TCP-SE bone graft substitute exhibits sufficient adhesion in biological microenvironments and osteoinductive activity, angiogenic effect and anti-inflammatory as well as anti-oxidative effect in vitro and in vivo. Moreover, the PDT-TCP-SE can protect BMSCs from erastin-induced ferroptosis through the Sirt1/Nrf2/GPX4 antioxidant pathway, which, in together, demonstrated the bone graft substitute material as an emerging biomaterial with potential clinical application for the future treatment of osteoporotic bone defect. Statement of significanceInjectable, anti-collapse, adhesive, plastic and bioactive bone graft substitute was successfully synthesized. Incorporation of SeNPs with PDT into β-TCP regenerated new bone in-situ by moderating oxidative stress in osteoporotic bone defects area. The PDT-TCP-SE bone graft substitute reduced high ROS levels in osteoporotic bone defect microenvironment. The bone graft substitute could also moderate oxidative stress and inhibit ferroptosis via Sirt1/Nrf2/GPX4 pathway in vitro. Moreover, the PDT-TCP-SE bone graft substitute could alleviate the inflammatory environment and promote bone regeneration in osteoporotic bone defect in vivo. This biomaterial has the advantages of simple synthesis, biocompatibility, anti-collapse, injectable, and regulation of oxidative stress level, which has potential application value in bone tissue engineering.

Coatless modification of 3D-printed Ti6Al4V implants through tailored Cu ion implantation combined with UV photofunctionalization to enhance cell attachment, osteogenesis and angiogenesis

The three-dimensional-printed Ti6Al4V implant (3DTi) has been widely accepted for the reconstruction of massive bone defects in orthopedics owing to several advantages, such as its tailored shape design, avoiding bone graft and superior bone-implant interlock. However, the osteoinduction activity of 3DTi is inadequate when applied clinically even though it exhibits osteoconduction. This study developes a comprehensive coatless strategy for the surface improvement of 3DTi through copper (Cu) ion implantation and ultraviolet (UV) photofunctionalization to enhance osteoinductivity. The newly constructed functional 3DTi (UV/Ti-Cu) achieved stable and controllable Cu doping, sustained Cu2+ releasing, and increased surface hydrophilicity. By performing cellular experiments, we determined that the safe dose range of Cu ion implantation was less than 5×1016 ions/cm2. The implanted Cu2+ enhanced the ALP activity and the apatite formation ability of bone marrow stromal cells (BMSCs) while slightly decreasing proliferation ability. When combined with UV photofunctionalization, cell adhesion and proliferation were significantly promoted and bone mineralization was further increased. Meanwhile, UV/Ti-Cu was conducive to the migration and angiogenesis of human umbilical vein endothelial cells (HUVECs) in vitro, theoretically facilitating vascular coupling osteogenesis. In conclusion, UV/Ti-Cu is a novel attempt to apply two coatless techniques for the surface modification of 3DTi. In addition, it is considered a potential bone substrate for repairing bone defects.

Zinc-energized dynamic hydrogel accelerates bone regeneration via potentiating the coupling of angiogenesis and osteogenesis.

Insufficient initial vascularization plays a pivotal role in the ineffectiveness of bone biomaterials for treating bone defects. Consequently, enhancing the angiogenic properties of bone repair biomaterials holds immense importance in augmenting the efficacy of bone regeneration. In this context, we have successfully engineered a composite hydrogel capable of promoting vascularization in the process of bone regeneration. To achieve this, the researchers first prepared an aminated bioactive glass containing zinc ions (AZnBg), and hyaluronic acid contains aldehyde groups (HA-CHO). The composite hydrogel was formed by combining AZnBg with gelatin methacryloyl (GelMA) and HA-CHO through Schiff base bonding. This composite hydrogel has good biocompatibility. In addition, the composite hydrogel exhibited significant osteoinductive activity, promoting the activity of ALP, the formation of calcium nodules, and the expression of osteogenic genes. Notably, the hydrogel also promoted umbilical vein endothelial cell migration as well as tube formation by releasing zinc ions. The results of in vivo study demonstrated that implantation of the composite hydrogel in the bone defect of the distal femur of rats could effectively stimulate bone generation and the development of new blood vessels, thus accelerating the bone healing process. In conclusion, the combining zinc-containing bioactive glass with hydrogels can effectively promote bone growth and angiogenesis, making it a viable option for the repair of critical-sized bone defects.

In vivo study on osteogenic efficiency of nHA/ gel porous scaffold with nacre water-soluble matrix

Background/purposeNano-hydroxyapatite (nHA)/ gel porous scaffolds loaded with WSM carriers are promising bone replacement materials that can improve osseointegration ability. This investigation aimed to evaluate the osteoinductive activity by implanting the composition of nano-hydroxyapatite (nHA)/ Gel porous scaffolds as a carrier of WSM via an animal model. Materials and methods: WSM was extracted and nHA was added to the matrix to construct porous composite scaffolds. The dose-effect curve of WSM concentration and alkaline phosphatase (ALP) activity was made by culturing rat osteoblasts and examining the absorbance. Three different materials were implanted into critical size defects (CSD) in the skulls of rats, which were further divided into four groups: WSM nHA /Gel group, n-WSM nHA /Gel group, HA powder group, and control group. Results: WSM (150 μg/mL-250μg/mL) effectively improved the activity of ALP in rat osteoblasts. All rats in each group had normal healing. WSM-loaded nHA /Gel group showed better performance on newly-formed bone tissue of rat skull and back at 4th week and 8th week, respectively. At the 4th week, the network of woven bone formed in the WSM-loaded nHA/Gel scaffold material. At 8th week, the reticular trabecular bone in the WSM-loaded scaffold material became dense lamellar bone, and the defect was mature lamellar bone. In the subcutaneous implantation experiment, WSM-loaded nHA/Gel scaffold material showed a better performance of heterotopic ossification than the pure nHA/Gel scaffold material. Conclusion: WSM promotes osteoblast differentiation and bone mineralization. The results confirm that the nHA/ Gel Porous Scaffold with Nacre Water-Soluble Matrix has a significant bone promoting effect and can be used as a choice for tissue engineering to repair bone defects.

Fabrication of bioactive glass/phosphorylated chitosan composite scaffold and its effects on MC3T3-E1 cells

This study aimed to synthesize bioactive glass (BG) and phosphorylated chitosan (PCS), and fabricate a BG/PCS composite scaffold. The physical properties (mechanical strength, swelling degree, and degradation rate) of the BG/PCS scaffold were tested. The in vitro mineralization properties of composite scaffolds in simulated body fluid were investigated. MC3T3-E1 cell responses with the BG/PCS scaffold were investigated using live/dead cell staining, actin staining, alkaline phosphatase (ALP) activity, and Alizarin red staining. Our results showed that the scaffold had an inner porous structure, good swelling properties, and good degradation rate. After immersion in SBF, the scaffolds demonstrated high properties in inducing mineralization. Leaching solutions of the composite scaffolds exhibited good cytocompatibility. MC3T3-E1 cells adhered, spread, and proliferated on the scaffold. The BG/PCS composite scaffold showed osteo-inductive activity by increasing ALP activity and calcium deposition. Our results indicated that the BG/PCS scaffold had potential applications as a bone-defect repair biomaterial.

A parathyroid hormone related supramolecular peptide for multi-functionalized osteoregeneration

Supramolecular peptide nanofiber hydrogels are emerging biomaterials for tissue engineering, but it is difficult to fabricate multi-functional systems by simply mixing several short-motif-modified supramolecular peptides because relatively abundant motifs generally hinder nanofiber cross-linking or the formation of long nanofiber. Coupling bioactive factors to the assembling backbone is an ideal strategy to design multi-functional supramolecular peptides in spite of challenging synthesis and purification. Herein, a multi-functional supramolecular peptide, P1R16, is developed by coupling a bioactive factor, parathyroid hormone related peptide 1 (PTHrP-1), to the basic supramolecular peptide RADA16-Ⅰ via solid-phase synthesis. It is found that P1R16 self-assembles into long nanofibers and co-assembles with RADA16-Ⅰ to form nanofiber hydrogels, thus coupling PTHrP-1 to hydrogel matrix. P1R16 nanofiber retains osteoinductive activity in a dose-dependent manner, and P1R16/RADA16-Ⅰ nanofiber hydrogels promote osteogenesis, angiogenesis and osteoclastogenesis in vitro and induce multi-functionalized osteoregeneration by intramembranous ossification and bone remodeling in vivo when loaded to collagen (Col) scaffolds. Abundant red blood marrow formation, ideal osteointegration and adapted degradation are observed in the 50% P1R16/Col scaffold group. Therefore, this study provides a promising strategy to develop multi-functional supramolecular peptides and a new method to topically administrate parathyroid hormone or parathyroid hormone related peptides for non-healing bone defects.

Effect of Er:YAG Pulsed Laser-Deposited Hydroxyapatite Film on Titanium Implants on M2 Macrophage Polarization In Vitro and Osteogenesis In Vivo.

In a previous study, we successfully coated hydroxyapatite (HAp) onto titanium (Ti) plates using the erbium-doped yttrium aluminum garnet pulsed-laser deposition (Er:YAG-PLD) method. In this study, we performed further experiments to validate the in vitro osteogenic properties, macrophage polarization, and in vivo osseointegration activity of HAp-coated Ti (HAp-Ti) plates and screws. Briefly, we coated a HAp film onto the surfaces of Ti plates and screws via Er:YAG-PLD. The surface morphological, elemental, and crystallographic analyses confirmed the successful surface coating. The macrophage polarization and osteogenic induction were evaluated in macrophages and rat bone marrow mesenchymal stem cells, and the in vivo osteogenic properties were studied. The results showed that needle-shaped nano-HAp promoted the early expression of osteogenic and immunogenic genes in the macrophages and induced excellent M2 polarization properties. The calcium deposition and osteocalcin production were significantly higher in the HAp-Ti than in the uncoated Ti. The implantation into rat femurs revealed that the HAp-coated materials had superior osteoinductive and osseointegration activities compared with the Ti, as assessed by microcomputed tomography and histology. Thus, HAp film on sandblasted Ti plates and screws via Er:YAG-PLD enhances hard-tissue differentiation, macrophage polarization, and new bone formation in tissues surrounding implants both in vitro and in vivo.

Osteoinductive activity of photobiomodulation in an organotypic bone model

Photobiomodulation (PBM) is a technique that harnesses non-ionizing light at specific wavelengths, triggering the modulation of metabolic pathways, engendering favourable biological outcomes that reduce inflammation and foster enhanced tissue healing and regeneration. PBM holds significant promise for bone tissue applications due to its non-invasive nature and ability to stimulate cellular activity and vascularization within the healing framework. Notwithstanding, the impact of PBM on bone functionality remains largely undisclosed, particularly in the absence of influencing factors such as pathologies or regenerative therapies. This study aims to investigate the potential effects of PBM using red (660 nm) (RED) and near-infrared (808 nm) (NIR) wavelengths within an ex vivo bone culture system - the organotypic embryonic chicken femur model. A continuous irradiation mode was used, administering a total energy dose of 1.0 J, at an intensity of 100 mW for 10 s, which was repeated four times over the course of the 11-day culture period. The primary focus is on characterizing the expression of pivotal osteoblastic genes, the maturation and deposition of collagen, and the formation of bone mineral. Exposing femora to both RED and NIR wavelengths led to a notable increase in the expression of osteochondrogenic transcription factors (i.e., SOX9 and RUNX2), correlating with enhanced mineralization. Notably, NIR irradiation further elevated the expression of bone matrix-related genes and fostered enhanced deposition and maturation of fibrillar collagen. This study demonstrates that PBM has the potential to enhance osteogenic functionality within a translational organotypic bone culture system, with the NIR wavelength showing remarkable capabilities in augmenting the formation and maturation of the collagenous matrix.