Rat Bone Mesenchymal Stem Cells Research Articles

Composite bioink incorporating cell-laden liver decellularized extracellular matrix for bioprinting of scaffolds for bone tissue engineering

The field of bone tissue engineering (BTE) has witnessed a revolutionary breakthrough with the advent of three-dimensional (3D) bioprinting technology, which is considered an ideal choice for constructing scaffolds for bone regeneration. The key to realizing scaffold biofunctions is the selection and design of an appropriate bioink, and existing bioinks have significant limitations. In this study, a composite bioink based on natural polymers (gelatin and alginate) and liver decellularized extracellular matrix (LdECM) was developed and used to fabricate scaffolds for BTE using 3D bioprinting. Through in vitro studies, the concentration of LdECM incorporated into the bioink was optimized to achieve printability and stability and to improve the proliferation and osteogenic differentiation of loaded rat bone mesenchymal stem cells (rBMSCs). Furthermore, in vivo experiments were conducted using a Sprague Dawley rat model of critical-sized calvarial defects. The proposed rBMSC-laden LdECM–gelatin–alginate scaffold, bioprinted layer-by-layer, was implanted in the rat calvarial defect and the development of new bone growth was studied for four weeks. The findings showed that the proposed bioactive scaffolds facilitated angiogenesis and osteogenesis at the defect site. The findings of this study suggest that the developed rBMSC-laden LdECM–gelatin–alginate bioink has great potential for clinical translation and application in solving bone regeneration problems.

A coaxial electrospun mat coupled with piezoelectric stimulation and atorvastatin for rapid vascularized bone regeneration.

The repair of critical bone defects caused by various clinical conditions needs to be addressed urgently, and the regeneration of large bone defects depends on early vascularization. Therefore, enhanced vascularization of artificial bone grafts may be a promising strategy for the regeneration of critical-sized bone defects. Taking into account the importance of rapid angiogenesis during bone repair and the potential of piezoelectric stimulation in promoting bone regeneration, novel coaxial electrospun mats coupled with piezoelectric materials and angiogenic drugs were fabricated in this study using coaxial electrospinning technology, with a shell layer loaded with atorvastatin (AVT) and a core layer loaded with zinc oxide (ZnO). AVT was used as an angiogenesis inducer, and piezoelectric stimulation generated by the zinc oxide was used as an osteogenesis enhancer. The multifunctional mats were characterized in terms of morphology, core-shell structure, piezoelectric properties, drug release, and mechanical properties, and their osteogenic and angiogenic capabilities were validated in vivo and ex vivo. The results revealed that the coaxial electrospun mats exhibit a porous surface morphology and nanofibers with a core-shell structure, and the piezoelectricity of the mats improved with increasing ZnO content. Excellent biocompatibility, hydrophilicity and cell adhesion were observed in the multifunctional mats. Early and rapid release of AVT in the fibrous shell layer of the mat promoted angiogenesis in human umbilical vascular endothelial cells (HUVECs), whereas ZnO in the fibrous core layer harvested bioenergy and converted it into electrical energy to enhance osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs), and both modalities synergistically promoted osteogenesis and angiogenesis. Furthermore, optimal bone regeneration was achieved in a model of critical bone defects in the rat mandible. This osteogenesis-promoting effect was induced by electrical stimulation via activation of the calcium signaling pathway. This multifunctional mat coupling piezoelectric stimulation and atorvastatin promotes angiogenesis and bone regeneration, and shows great potential in the treatment of large bone defects.

More than the barrier effect: Biodegradable Mg-Ag alloy membranes for guided bone/tissue regeneration

Magnesium (Mg) and its alloys have emerged as promising candidates for guided bone/tissue regeneration (GBR/GTR) due to their good mechanical properties, biosafety, and biodegradability. In this study, we present a pioneering application of Mg-Ag alloys featuring tunable corrosion behaviors for GBR/GTR membranes, showcasing their in vitro antibacterial effects, cell migration, and osteogenic differentiation abilities. Mg-Ag alloys with different Ag contents were engineered to facilitate the cell migration of murine fibroblasts (L929) and the osteogenic differentiation of rat bone mesenchymal stem cells (rBMSCs). The Mg-Ag alloy consisted of recrystallized α-Mg grains and fine Mg4Ag second phases, with an observable refinement in the average grain size to 5.6 µm with increasing Ag content. Among the alloys, Mg-9Ag exhibited optimal mechanical strength and moderate plasticity (tensile yield strength of 205.7 MPa, elongation of 20.3%, and a maximum bending load of 437.2 N). Furthermore, the alloying of Ag accelerated the cathodic reaction of pure Mg, leading to a slightly increased corrosion rate of the Mg-Ag alloys while maintaining acceptable general corrosion. Notably, compared with pure Mg, Mg-Ag alloys had superior antibacterial effects against Porphyromonas gingivalis (P. gingivalis) and Staphylococcus aureus (S. aureus). Taken together, these results provide evidence for the significant clinical potential of Mg-Ag alloys as GBR/GTR membranes.

Hierarchically Biomimetic Scaffolds with Anisotropic Micropores and Nanotopological Patterns to Promote Bone Regeneration via Geometric Modulation.

Structural engineering is an appealing means to modulate osteogenesis without the intervention of exogenous cells or therapeutic agents. In this work, a novel 3D scaffold with anisotropic micropores and nanotopographical patterns is developed. Scaffolds with oriented pores are fabricated via the selective extraction of water-soluble polyethylene oxide from its poly(ε-caprolactone) co-continuous mixture and uniaxial stretching. The plate apatite-like lamellae are subsequently hatched on the pore walls through surface-induced epitaxial crystallization. Such a unique geometric architecture yields a synergistic effect on the osteogenic capability. The prepared scaffold leads to a 19.2% and 128.0% increase in the alkaline phosphatase activity of rat bone mesenchymal stem cells compared to that of the scaffolds with only oriented pores and only nanotopographical patterns, respectively. It also induces the greatest upregulation of osteogenic-related gene expression in vitro. The cranial defect repair results demonstrate that the prepared scaffold effectively promotes new bone regeneration, as indicated by a 350% increase in collagen I expression in vivo compared to the isotropic porous scaffold without surface nanotopology after implantation for 14weeks. Overall, this work provides geometric motifs for the transduction of biophysical cues in 3D porous scaffolds, which is a promising option for tissue engineering applications.

Digital light processing bio-scaffolds of hydroxyapatite ceramic foams with multi-level pores using Pickering emulsions as the feedstock

To prepare bio-scaffolds with multi-stage pores, excellent mechanical and biological properties to meet the requirements of personalized bone repair, digital light processing using Pickering emulsion as paste has been proposed here firstly for porous hydroxyapatite scaffolds with complex shape and fine microstructure. It is found that dispersant content, solid loading and oil to water ratio of Pickering emulsions play vital roles on the controlling of pore morphology and pore size distribution of final hydroxyapatite ceramic foams. The multi-stage pores consist of millimeter-scale pores designed by 3D models and micro-pores below 10 µm derived from emulsion droplets. Due to the integration of hierarchical pores at different scale levels and micropores, hydroxyapatite ceramic foams possess outstanding compressive strength of 4.46–8.03 MPa at porosity of 76.59-72.96%. In vitro cell experiments illustrate that rat bone mesenchymal stem cells can spread and adhere to bio-scaffolds, promoting cell proliferation effectively and further verifying their good biocompatibility.

A sodium alginate/carboxymethyl chitosan dual-crosslinked injectable hydrogel scaffold with tunable softness/hardness for bone regeneration

Recently, injectable dual-crosslinked (DC) hydrogel scaffolds have attracted many attentions as a class of excellent bone regeneration biomaterials with in-situ tunable functions. However, the design of injectable DC hydrogels with cell behavior-compatible network structure and mechanical property remains a bottleneck. Herein, based on the in-situ gelling method, we constructed an injectable CMCS/PEG+SA/CaCl2 (CPSC) chemical/physical DC hydrogel scaffold with tunable softness/hardness mechanical properties and good biocompatibility. The formation mechanism and properties of the CPSC hydrogel scaffold were investigated by FTIR, XRD, rheometry, and mechanical testing. It is found that proper softness/hardness mechanical properties can be obtained by adjusting the secondary network structure of the hydrogel. The CPSC hydrogel scaffold prepared under optimal conditions can effectively promote cell infiltration, nutrient transport, and the osteogenic differentiation of rat bone mesenchymal stem cells (rBMSCs). The in vivo experiments show that the rBMSCs-loaded injectable CPSC hydrogels with appropriate mechanical properties can effectively promote bone reconstruction. This study has provided important guidance for the construction of injectable DC hydrogels with adjustable softness/hardness to promote osteogenesis for bone defect repair.

Fe3O4‐nanoparticle‐functionalized 3D‐printed injectable microgel

AbstractMagnetic Fe3O4 nanoparticles have attached attention in bone tissue engineering because of their superior magnetism and great biocompatibility. However, some disadvantages such as the potential risk of agglomeration impair their applications. Here, we proposed a hybrid magnetic nanocomposite microgel by the integration of Fe3O4 nanoparticles and digital lighting processing (DLP) three‐dimensional (3D) printing technology. The 3D‐printed microgels could be precisely customized by printing the mixture of gelatin methacryloyl (GelMA) solution and polydopamine‐coated Fe3O4 nanoparticles, in which polydopamine decoration improved the hydrophilicity and distribution of the incorporated Fe3O4. The degradable microgels could be injected through a 22‐G needle while retaining their original shape after injection. Interestingly, the addition of Fe3O4 nanoparticles into GelMA solution displayed improved printing accuracy. Moreover, these magnetic microgels were biocompatible in vitro and in vivo. After induction within osteogenic medium, addition of nanoparticles upregulated the osteogenic gene expression of rat bone mesenchymal stem cells (BMSCs). In a word, this work provides a magnetic microplatform, which shows great potential in bone tissue engineering.

Enhancing bone regeneration with a novel bioactive glass-functionalized polyetheretherketone scaffold by regulating the immune microenvironment

Polyetheretherketone (PEEK) has become a promising material for bone engineering due to its excellent mechanical properties, radiolucency and chemical resistance. However, its inherent bioinertness and lack of osteogenic activity induce a foreign body reaction and fibrous encapsulation, which limits its effectiveness in promoting bone regeneration. Herein, we develop a novel bioactive glass–functionalized PEEK scaffold (ADSP) to accelerate bone regeneration by immunoregulation. Strontium-doped bioactive glass nanoparticles loaded with alendronate (A-SrBG) were coated on the sulfonated PEEK scaffold by the strong adhesion ability of polydopamine. The released bioactive ions from the scaffold can improve the biocompatibilities and osteogenic activity of PEEK. In vitro results showed the ADSP scaffold promoted polarization of the M2 macrophages via the NF-κB pathway to enhance the osteogenic differentiation of rat bone mesenchymal stem cells (rBMSCs). Further, in vivo rat skull drilling model assessment revealed efficient polarization of M2 macrophage and desirable new bone formation. Thus, ADSP scaffold exerted osteoimmunomodulation effect to promote bone regeneration.

Self‐Adaptive MoO3−x Subnanometric Wires Incorporated Scaffolds for Osteosarcoma Therapy and Bone Regeneration

AbstractResidual tumor cells and bone tissue defects are two critical challenges in clinical osteosarcoma treatment. Herein, a subnanomedicine concept is proposed by developing a self‐adaptive functional tissue engineering scaffold constructed by integrating MoO3−x subnanometric wires onto 3D printing bioactive glass scaffolds. The MoO3−x subnanometric wires are synthesized by a one‐pot hydrothermal method, which aggregate in an acidic tumor microenvironment and react with hydrogen peroxide to produce reactive oxygen species for specific chemodynamic therapy. However, they can degrade rapidly under physiological conditions without causing toxicity. Moreover, self‐adaptively enhanced photothermal conversion enables tumor‐targeting photothermal therapy while enhancing chemodynamic therapy. Additionally, the Mo5+‐Mo6+ transition enables lipid peroxide accumulation and glutathione depletion, thereby resulting in the deactivation of glutathione peroxidase 4 protein and ferroptosis through Western blot analysis, confocal laser scanning microscopy observation, and mRNA transcriptome analysis. In addition to its robustness against osteosarcoma, the constructed scaffolds can stimulate rat bone mesenchymal stem cell differentiation and proliferation as well as promote osteogenesis in bone defects. Therefore, this multifunctional scaffold not only validates the subnanomedicine concept but also provides a promising clinical strategy for bone tissue engineering.

YTHDC2 inhibits rat bone mesenchymal stem cells osteogenic differentiation by accelerating RUNX2 mRNA degradation via m6A methylation

As the most abundant internal mRNA modification, N6-methyladenosine (m6A) RNA methylation has been found to influence many biological events including bone mesenchymal stem cells (BMSCs) osteogenic differentiation. YTH N6-methyladenosine RNA binding protein C2 （YTHDC2） is an m6A reading protein with the ability to mediate the decay of combined methylated mRNA, however its role in BMSCs osteogenic differentiation remains unknown. In this study, we first found an increase of RUNX family transcription factor 2 （RUNX2） expression and a decrease of YTHDC2 expression during the process of BMSCs osteogenic differentiation. Furthermore, we transfected BMSCs with YTHDC2 interference fragment, resulting in an increased content of RUNX2 mRNA and protein inside BMSCs. Finally, through RNA Immunoprecipitation experiments, we confirmed that YTHDC2 protein can bind to RUNX2 mRNA and accelerate its decomposition. Moreover, the immunofluorescence staining also showed a negative correlation between YTHDC2 and RUNX2. In conclusion, during BMSCs osteogenic differentiation, YTHDC2 protein showed decreased expression, resulting in a higher level of RUNX2 (mRNA and protein) expression inside cells, indicating YTHDC2 as a promising molecular target for the regulation of BMSCs osteogenic differentiation.

In Vitro and In Vivo Evaluation of Epidermal Growth Factor (EGF) Loaded Alginate-Hyaluronic Acid (AlgHA) Microbeads System for Wound Healing.

The management of skin injuries is one of the most common concerns in medical facilities. Different types of biomaterials with effective wound-healing characteristics have been studied previously. In this study, we used alginate (Alg) and hyaluronic acid (HA) composite (80:20) beads for the sustained release of epidermal growth factor (EGF) delivery. Heparin crosslinked AlgHA beads showed significant loading and entrapment of EGF. Encapsulated beads demonstrated biocompatibility with rat L929 cells and significant migration at the concentration of AlgHAEGF100 and AlgHAEGF150 within 24 h. Both groups significantly improved the expression of Fetal Liver Kinase 1 (FLK-1) along with the Intercellular Adhesion Molecule-1 (ICAM-1) protein in rat bone Mesenchymal stem cells (rbMSCs). In vivo assessment exhibited significant epithelialization and wound closure gaps within 2 weeks. Immunohistochemistry shows markedly significant levels of ICAM-1, FLK-1, and fibronectin (FN) in the AlgHAEGF100 and AlgHAEGF150 groups. Hence, we conclude that the EGF-loaded alginate-hyaluronic acid (AlgHA) bead system can be used to promote wound healing.

Lyophilized Platelet-Rich Fibrin Exudate-Loaded Carboxymethyl Chitosan/GelMA Hydrogel for Efficient Bone Defect Repair.

Platelet-rich fibrin (PRF) is an autologous growth factor carrier that promotes bone tissue regeneration, but its effectiveness is restrained by poor storage capabilities, uncontrollable concentration of growth factors, unstable shape, etc. Herein, we developed a photocrosslinkable composite hydrogel by incorporating lyophilized PRF exudate (LPRFe) into the carboxymethyl chitosan methacryloyl (CMCSMA)/gelatin methacryloyl (GelMA) hydrogel to effectively solve the dilemma of PRF. The hydrogel possessed suitable physical properties and sustainable release ability of growth factors in LPRFe. The LPRFe-loaded hydrogel could improve the adhesion, proliferation, migration, and osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs). Furthermore, the animal experiments demonstrated that the hydrogel possessed excellent biocompatibility and biodegradability, and the introduction of LPRFe in the hydrogel can effectively accelerate the bone healing process. Conclusively, the combination of LPRFe with CMCSMA/GelMA hydrogel may be a promising therapeutic approach for bone defects.

Eldecalcitol prevented OVX-induced osteoporosis through inhibiting BMSCs senescence by regulating the SIRT1-Nrf2 signal.

Background: Aging and oxidative stress are considered to be the proximal culprits of postmenopausal osteoporosis. Eldecalcitol (ED-71), a new active vitamin D derivative, has shown a good therapeutic effect on different types of osteoporosis, but the mechanism is unclear. This study focused on exploring whether ED-71 could prevent bone loss in postmenopausal osteoporosis by regulating the cell senescence of bone mesenchymal stem cells (BMSCs), and explaining its specific mechanism of action. Materials and methods: An ovariectomized (OVX) rat model was established and 30ng/kg ED-71 was administered orally once a day. The weight of rats was recorded regularly. Micro-computed tomography (CT) and histochemical staining were used to evaluate bone mass, histological parameters, and aging-related factors. Rat bone mesenchymal stem cells were extracted and cultivated in vitro. Aging cells were marked with senescence-associated β-gal (SA-β-gal) dyeing. The mRNA and protein levels of aging-related factors and SIRT1-Nrf2 signal were detected by RT-PCR, Western blot, and immunofluorescence staining. The reactive oxygen species (ROS) levels were detected by DCFH-DA staining. Results: Compared with the Sham group, the bone volume of the ovariectomized group rats decreased while their weight increased significantly. ED-71 prevented bone loss and inhibited weight gain in ovariectomized rats. More importantly, although the expression of aging-related factors in the bone tissue increased in the ovariectomized group, the addition of ED-71 reversed changes in these factors. After extracting and in vitro culturing bone mesenchymal stem cells, the proportion of aging bone mesenchymal stem cells was higher in the ovariectomized group than in the Sham group, accompanied by a significant decrease in the osteogenic capacity. ED-71 significantly improved the bone mesenchymal stem cells senescence caused by ovariectomized. In addition, ED-71 increased the expression of SIRT1 and Nrf2 in ovariectomized rat bone mesenchymal stem cells. Inhibition of SIRT1 or Nrf2 decreased the inhibitory effect of ED-71 on bone mesenchymal stem cells senescence. ED-71 also showed a suppression effect on the reactive oxygen species level in bone mesenchymal stem cells. Conclusion: Our results demonstrated that ED-71 could inhibit the cell senescence of bone mesenchymal stem cells in ovariectomized rats by regulating the SIRT1-Nrf2 signal, thereby preventing bone loss caused by osteoporosis.

Dual-crosslinked network of polyacrylamide-carboxymethylcellulose hydrogel promotes osteogenic differentiation in vitro

In our previous study, we successfully designed a dual-crosslinked network hydrogel by introducing the monomers acrylamide (AM), carboxymethylcellulose (CMC), zeolitic imidazolate framework-8 (ZIF-8), and alendronate (Aln). With the simultaneous presentation of physical and chemical crosslinks, the fabricated hydrogel with 10 % concentration of Aln@ZIF-8 (PAM-CMC-10%Aln@ZIF-8) exhibited excellent mechanical characteristics, high Aln loading efficiency (63.83 %), and a slow release period (6 d). These results demonstrate that PAM-CMC-10%Aln@ZIF-8 is a potential carrier for delaying Aln. In this study, we mainly focused on the biocompatibility and osteogenic ability of PAM-CMC-10%Aln@ZIF-8 in vitro, which is a continuation of our previous work. First, this study investigated the biocompatibility of dual-crosslinked hydrogels using calcein-AM/Propidium Iodide and cell counting kit-8. The morphology of rat bone mesenchymal stem cells was assessed using FITC-phalloidin/DAPI and vinculin immunostaining. Finally, osteogenic induction ability in vitro was assessed via alkaline phosphatase expression and alizarin red S staining, which was also confirmed using real-time PCR at the gene level and immunofluorescence at the protein level. The results indicated that the introduction of Aln enabled a dual-crosslinked hydrogel with superior biocompatibility and outstanding osteogenic differentiation ability in vitro, providing a solid foundation for subsequent animal experiments in vivo.

3D bioprinting of cell-laden nano-attapulgite/gelatin methacrylate composite hydrogel scaffolds for bone tissue repair

Bone tissue engineering (BTE) has proven to be a promising strategy for bone defect repair. Due to its excellent biological properties, gelatin methacrylate (GelMA) hydrogels have been used as bioinks for 3D bioprinting in some BTE studies to produce scaffolds for bone regeneration. However, applications for load-bearing defects are limited by poor mechanical properties and a lack of bioactivity. In this study, 3D printing technology was used to create nano-attapulgite (nano-ATP)/GelMA composite hydrogels loaded into mouse bone mesenchymal stem cells (BMSCs) and mouse umbilical vein endothelial cells (MUVECs). The bioprintability, physicochemical properties, and mechanical properties were all thoroughly evaluated. Our findings showed that nano-ATP groups outperform the control group in terms of printability, indicating that nano-ATP is beneficial for printability. Additionally, after incorporation with nano-ATP, the mechanical strength of the composite hydrogels was significantly improved, resulting in adequate mechanical properties for bone regeneration. The presence of nano-ATP in the scaffolds has also been studied for cell-material interactions. The findings show that cells within the scaffold not only have high viability but also a clear proclivity to promote osteogenic differentiation of BMSCs. Besides, the MUVECs-loaded composite hydrogels demonstrated increased angiogenic activity. A cranial defect model was also developed to evaluate the bone repair capability of scaffolds loaded with rat BMSCs. According to histological analysis, cell-laden nano-ATP composite hydrogels can effectively improve bone regeneration and promote angiogenesis. This study demonstrated the potential of nano-ATP for bone tissue engineering, which should also increase the clinical practicality of nano-ATP.

Bismuth-coated 80S15C bioactive glass scaffolds for photothermal antitumor therapy and bone regeneration.

Background: Malignant bone tumors usually occur in young people and have a high mortality and disability rate. Surgical excision commonly results in residual bone tumor cells and large bone defects, and conventional radiotherapy and chemotherapy may cause significant side effects. In this study, a bifunctional Bi-BG scaffold for near-infrared (NIR)-activated photothermal ablation of bone tumors and enhanced bone defect regeneration is fabricated. Methods: In this study, we prepared the Bi-BG scaffold by in-situ generation of NIR-absorbing Bi coating on the surface of a 3D-printing bioactive glass (BG) scaffold. SEM was used to analyze the morphological changes of the scaffolds. In addition, the temperature variation was imaged and recorded under 808nm NIR laser irradiation in real time by an infrared thermal imaging system. Then, the proliferation of rat bone mesenchymal stem cells (rBMSCs) and Saos-2 on the scaffolds was examined by CCK-8 assay. ALP activity assay and RT-PCR were performed to test the osteogenic capacity. For in vivo experiments, the nude rat tumor-forming and rat calvarial defect models were established. At 8weeks after surgery, micro-CT, and histological staining were performed on harvested calvarial samples. Results: The Bi-BG scaffolds have outstanding photothermal performance under the irradiation of 808nm NIR at different power densities, while no photothermal effects are observed for pure BG scaffolds. The photothermal temperature of the Bi-BG scaffold can be effectively regulated in the range 26-100°C by controlling the NIR power density and irradiation duration. Bi-BG scaffolds not only significantly induces more than 95% of osteosarcoma cell death (Saos-2) in vitro, but also effectively inhibit the growth of bone tumors in vivo. Furthermore, they exhibit excellent capability in promoting osteogenic differentiation of rBMSCs and finally enhance new bone formation in the calvarial defects of rats. Conclusion: The Bi-BG scaffolds have bifunctional properties of photothermal antitumor therapy and bone regeneration, which offers an effective method to ablate malignant bone tumors based on photothermal effect.

SIS membrane modification to improve antimicrobial and osteogenic properties for guide bone regeneration

The guided bone regeneration (GBR) technique is the most common and durable approach to repairing bone defects in periodontal surgery. However, membrane exposure causes bacterial infiltration, which lowers the functional integrity of the barrier membrane and destroys bone repair. Here, an antibacterial peptide-modified small intestinal submucosa (SIS) membrane is used as a new GBR membrane for effective bone regeneration. The peptide JH8194 was placed into chitosan microspheres to preserve its stability and allow for sustained release, which realizes rapid and efficient functional modification of the SIS membrane. Biocompatibility and certain antibacterial activities were found in the modified SIS membrane (SIS@CS-JH8194). Additionally, in vitro experiments showed that SIS@CS-JH8194 promoted the expression of osteogenic-related factors and decreased the secretion of inflammatory factors in rat bone mesenchymal stem cells. In vivo experiments showed that SIS@CS-JH8194 could effectively promote bone regeneration in rat skull defects. In this work, we created a new antibacterial GBR membrane to help avoid postoperative infection and improve bone tissue regeneration.

Black tantalic oxide submicro-particles coating on PEEK fibers woven into fabrics as artificial ligaments with photothermal antibacterial effect and osteogenic activity for promoting ligament-bone healing

• Black tantalic oxide (BTO) submicro-particles were prepared. • PEEK fibers with BTO coating were woven into fabrics (PBT) as artificial ligaments • PBT exhibited optimized surface properties and photothermal antibacterial effects. • PBT with excellent osteogenic activity promoted ligament-bone healing Design of artificial ligaments possessing both osteogenic activity and antibacterial effect that promotes ligament-bone healing and prevents bacterial infection in bone tunnels for anterior cruciate ligament (ACL) reconstruction remains a significant challenge. In this study, black tantalic oxide (BTO) submicro-particles with oxygen vacancies and structure defects were fabricated by using traditional white tantalic oxide (WTO) through magnesium thermal reduction (MTR) method, and BTO was coated on polyetheretherketone (PEEK) fibers (PKF), which were woven into fabrics (PBT) as artificial ligaments. PBT with BTO coating exhibited excellent photothermal performance, which possessed not only antibacterial effects in vitro but also anti-infective ability in vivo. PBT with optimized surface properties (e.g., submicro-topography and hydrophilicity) not only significantly facilitated rat bone mesenchymal stem cells (BMSC) responses (e.g., proliferation and osteogenic differentiation) in vitro but also stimulated new bone formation for ligament-bone healing in vivo. The presence of oxygen vacancies and structure defects in BTO did not change the surface properties and osteogenic activity of BPT while displaying an outstanding photothermal antibacterial effect. In summary, BPT with osteogenic activity and photothermal antibacterial effect promoted bone regeneration and prevented bacterial infection, thereby promoting ligament-bone healing. Therefore, PBT would have tremendous potential as a novel artificial ligament for ACL reconstruction.

Cobalt Chloride Promotes Osteogenesis of Rat Bone Marrow Mesenchymal Stem Cells In Vitro and In Vivo

This work aimed to investigate the effect of low-concentration cobalt chloride on the in vitro and in vivo proliferation of rat bone mesenchymal stem cells, the expression of hypoxia-inducing fraction-1 alpha and the related osteogenic genes. The bone mesenchymal stem cells were isolated from bone marrow of rats, and the surface biomarkers were identified by immunofluorescence staining and flow cytometry. The differentiation of bone mesenchymal stem cells was measured by alizarin red and alkaline phosphatase staining. The bone mesenchymal stem cells were treated with cobalt chloride at different concentrations and cell viability was assessed by cell counting kit 8. Cell migration was detected by Transwell and wound healing assay. The expression of collagen type 1, bone morphogenetic protein-2, runt-related transcription factor 2, alkaline phosphatase and hypoxia-inducing fraction-1 alpha were measured by quantitative real time polymerase chain reaction assay. The large segmental defect model was made to mimic the in vivo bone defect. The bone mesenchymal stem cells-collagen sponge scaffold was adopted for in vivo treatment and histological analysis of femur structure was performed to assess the effects of cobalt chloride-treated bone mesenchymal stem cells in promoting bone formation. X-ray and micro computed tomography were performed to observe bone structure. The cluster of differentiation 90 and cluster of differentiation 44 were highly expressed and cluster of differentiation 45 expression was relatively low in isolated bone mesenchymal stem cells. The cobalt chloride at 300 and 400 μmol/l could effectively suppress cell proliferation, compared with the control group. The low dose of cobalt chloride (50 μmol/l and 100 μmol/l) could promote cell proliferation. The cobalt chloride at 100 μmol/l could increase the positive staining of alkaline phosphatase and alizarin red. The expression of collagen type 1, bone morphogenetic protein-2, runt-related transcription factor 2, alkaline phosphatase and hypoxiainducing fraction-1 alpha were statistically up-regulated by cobalt chloride treatment. The cobalt chloridebone mesenchymal stem cells-collagen scaffold effectively accelerated the bone regeneration, increased new bone deposition and bone morphogenetic protein-2 expression in femur tissues. Appropriate concentration of cobalt chloride can promote the proliferation of bone mesenchymal stem cells and up-regulate the expression of hypoxia-inducing fraction-1 alpha and osteogenic genes in vitro, simultaneously promoted bone regeneration in vivo.

Application of Bone Marrow-Derived Macrophages Combined with Bone Mesenchymal Stem Cells in Dual-Channel Three-Dimensional Bioprinting Scaffolds for Early Immune Regulation and Osteogenic Induction in Rat Calvarial Defects.

The host immune response to biomaterials is critical for determining scaffold fate and bone regeneration outcomes. Three-dimensional (3D) bioprinted scaffolds encapsulated with living cells can improve the inflammatory microenvironment and further accelerate bone repair. Here, we screened and adopted 8% methacrylamidated gelatin (GelMA)/1% methacrylamidated hyaluronic acid (HAMA) as the encapsulation system for rat bone marrow-derived macrophages (BMMs) and 3% Alginate/0.5 mg/mL graphene oxide (GO) as the encapsulation system for rat bone mesenchymal stem cells (BMSCs), thus forming a dual-channel bioprinting scaffold. The 8% GelMA/1% HAMA/3% Alginate/0.5 mg/mL GO (8/1/3/0.5) group could form a scaffold with a stable structure, good mechanical properties, and satisfied biocompatibility. When exploring the crosstalk between BMMs and BMSCs in vitro, we found that BMSCs could promote the polarization of BMMs to M2 type at the early stage, reduce the pro-inflammatory gene expression, and increase anti-inflammatory gene expression; conversely, BMMs can promote the osteogenic differentiation of BMSCs. In addition, in the model of rat calvarial defects, the dual-channel scaffold encapsulated with BMMs and BMSCs was more effective than the single-cell scaffold and the acellular scaffold. The paracrine of BMMs and BMSCs in the biodegradable dual-channel scaffold effectively promoted the M2-type polarization of macrophages in the microenvironment of early bone defects, avoided excessive inflammatory responses, and further promoted bone repair. In conclusion, our findings suggested that using 3D bioprinting to simultaneously encapsulate two primary cells of BMMs and BMSCs in a dual-channel system may be an effective way to promote bone repair from the perspective of early immune regulation and late induction of osteogenesis.