Rabbit Bone Marrow Stromal Cells Research Articles

Bone marrow stromal cell-derived exosome combinate with fibrin on tantalum coating titanium implant accelerates osseointegration.

This study aims to present a sustainably releasing system of exosomes-fibrin combinate loaded on tantalum-coating titanium implants. We hope to investigate potential effects of the system on osseointegration between tantalum coating titanium implants and its surrounding bone tissue. Exosomes derived from rabbit bone marrow stromal cells (rBMSCs) and fibrin were deposited onto the micro-nanostructure tantalum coating surface (Ta + exo + FI) and compared to control groups, including tantalum coating (Ta), tantalum coating loaded exosomes (Ta + exo) and tantalum coating loaded fibrin (Ta + FI). The optimal concentration of loading exosomes, exosomes uptake capacity by BMSCs, and the effect of controlled-release by fibrin were assessed by laser scanning confocal microscope (LCSM) and microplate reader. The optimal concentration of exosomes was 1μg/μL. Adhesion, proliferation, and osteogenic differentiation ability of BMSCs on different materials were assessed in vitro. Finally, osseointegrative capacity of Ta, Ta + exo, Ta + FI, Ta + exo + FI implants in rabbit tibia were respectively evaluated with histology and bone-implant contact ratio (BIC%). It was demonstrated that exosome sustained-release system with fibrin loading on the tantalum coating was successfully established. Fibrin contribute to exosomes release extension from 2d to 6d. Furthermore, Ta + exo + FI significantly promoted adhesion, proliferation, and osteogenic differentiation of BMSCs. In vivo, the implants in Ta + exo + FI group displayed the highest osseointegrative capability than those in other groups. It is concluded that this exosome delivery system on the implants may be an effective way for tantalum coating titanium implants to promote osseointegration between implant and its surrounding bone tissue.

Effect of chemical modification on physicochemical and biological properties of chondroitin sulfate

Chondroitin sulfate (CS) derivatives are useful biomacromolecules for fabrication of biomaterials. However, chemical modifications of CS molecular structure during processing may alter its physicochemical and biological properties. Here, we studied these changes in molecular and biological functions following CS oxidation to different oxidation. Under ultraviolet visible (UV–Vis) spectroscopy, CS exhibited a blue shift in characteristic absorption peaks after the oxidation. The thermo-stability of the modified CS was also weaker than its original molecular form. Both FTIR and NMR results demonstrated distinct structural changes at the molecular level after oxidation. In vitro study showed that rabbit bone marrow stromal cells cultured with oxidized CS (CSA) containing cell culture medium exhibited viability comparable to normal cell culture medium for CSA concentration less than 125 mg/mL. However, CSA may also inhibit proliferation of these cells. Besides, unmodified CS could induce a chondrogenesis of stem cells, but this function was weakened after chemical modification. Interestingly, chemical modification altered physicochemical and biological properties in substitution degree-dependent manner with the highly oxidized CS exhibiting the lowest stability and chondrogenic induction. These results indicated that chemical modification of biomacromolecules, such as CS, could change both their physicochemical properties and biological functions, suggesting the need to carefully control parameters during biomaterial processing and fabrication.

Degradation-Kinetics-Controllable and Tissue-Regeneration-Matchable Photocross-linked Alginate Hydrogels for Bone Repair.

Photocross-linked alginate hydrogels, due to their biodegradability, biocompatibility, strong control for gelling kinetics in space and time, and admirable adaptability for in situ polymerization with a minimally invasive approach in surgical procedures, have created great expectations in bone regeneration. However, hydrogels with suitable degradation kinetics that can match the tissue regeneration process have not been designed, which limits their further application in bone tissue engineering. Herein, we finely developed an oxidation strategy for alginate to obtain hydrogels with more suitable degradation rates and comprehensively explored their physical and biological performances in vitro and in vivo to further advance the clinical application for the hydrogels in bone repair. The physical properties of the gels can be tuned via tailoring the degree of alginate oxidation. In particular, in vivo degradation studies showed that the degradation rates of the gels were significantly increased by oxidizing alginate. The activity, proliferation, initial adhesion, and osteogenic differentiation of rat and rabbit bone marrow stromal cells (BMSCs) cultured with/in the hydrogels were explored, and the results demonstrated that the gels possessed excellent biocompatibility and that the encapsulated BMSCs were capable of osteogenic differentiation. Furthermore, in vivo implantation of rabbit BMSC-loaded gels into tibial plateau defects of rabbits demonstrated the feasibility of hydrogels with appropriate degradation rates for bone repair. This study indicated that hydrogels with increasingly controllable and matchable degradation kinetics and satisfactory bioproperties demonstrate great clinical potential in bone tissue engineering and regenerative medicine and could also provide references for drug/growth-factor delivery therapeutic strategies for diseases requiring specific drug/growth-factor durations of action.

Tantalum boride as a biocompatible coating to improve osteogenesis of the bionano interface.

A proper biological microenvironment conducive to tissue repair and regeneration, while the bioimplant interface directly affects the local microenvironment. In this study, to improve the biological microenvironment, a nanosized tantalum boride (Ta-B) was coated on a titanium alloy substrate (Ti6Al4V, TC4) using magnetron cosputtering. The sample surface was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). To investigate the effects of tantalum boride coating on the microenvironment, rabbit bone marrow stromal cells (BMSCs), and RAW 264.7 cells were respectively seeded on the sample surface and relevant experiments were conducted in vitro. The pure tantalum coating (Ta) and naked TC4 were prepared as controls. Our results showed that the Ta-B coating enhanced cell proliferation and adhesion and inhibited the inflammatory response. Findings of alkaline phosphatase (ALP) staining, alizarin red staining and real-time PCR for osteoblastic gene expression indicated that Ta-B and Ta coating improve the osteogenesis, in which Ta-B coating showed higher osteogenesis than Ta coating. Thus, this study suggests that Ta-B coating with excellent biocompatibility could have new applications for wound healing in bone tissue engineering.

Direct 3-D printing of Ti-6Al-4V/HA composite porous scaffolds for customized mechanical properties and biological functions.

Customized scaffold plays an important role in bone tissue regeneration. Precise control of the mechanical properties and biological functions of scaffolds still remains a challenge. In this study, metal and ceramic biomaterials are composited by direct 3-D printing. Hydroxyapatite (HA) powders with diameter of about 25 μm and Ti-6Al-4V powders with diameter of 15-53 μm were mixed and modulated for preparing 3-D printing inks formulation. Three different proportions of 8, 10, and 25 wt.% HA specimens were printed with same porosity of 72.1%. The green bodies of the printed porous scaffolds were sintered at 1,150°C in the atmosphere of argon furnace and conventional muffle furnace. The porosities of the final 3-D-printed specimens were 64.3 ± 0.8% after linear shrinkage of 6.5 ± 0.8%. The maximum compressive strength of the 3-D-printed scaffolds can be flexibly customized in a wide range. The maximum compressive strength of these scaffolds in this study ranged from 3.07 to 60.4 MPa, depending on their different preparation process. The phase composition analysis and microstructure characterization indicated that the Ti-6Al-4V and HA were uniformly composited in the scaffolds. The cytocompatibility and osteogenic properties were evaluated in vitro with rabbit bone marrow stromal cells (rBMSCs). Differentiation and proliferation of rBMSCs indicated good biocompatibility of the 3-D-printed scaffolds. The proposed 3-D printing of Ti-6Al-4V/HA composite porous scaffolds with tunable mechanical and biological properties in this study is a promising candidate for bone tissue engineering.

Sonic hedgehog promotes chondrogenesis of rabbit bone marrow stem cells in a rotary cell culture system

BackgroundSonic hedgehog (Shh) is an important signalling protein involved in the induction of early cartilaginous differentiation. Herein, we demonstrate that Shh markedly induces chondrogenesis of rabbit bone marrow stromal cells (BMSCs) under microgravity conditions, and promotes cartilage regeneration.ResultsIn the rotary cell culture system (RCCS), chondrogenic differentiation was revealed by stronger Toluidine Blue and collagen II immunohistochemical staining in the Shh transfection group, and chondroinductive activity of Shh was equivalent to that of TGF-β. Western blotting and qRT-PCR analysis results verified the stronger expression of Sox9, aggrecan (ACAN), and collagen II in rabbit BMSCs treated with Shh or TGF-β in a microgravity environment. Low levels of chondrogenic hypertrophy, osteogenesis, and adipogenesis-related factors were detected in all groups. After transplantation in vivo, histological analysis revealed a significant improvement in cartilage and subchondral repair in the Shh transfection group.ConclusionsThese results suggested that Shh signalling promoted chondrogenesis in rabbit BMSCs under microgravity conditions equivalent to TGF-β, and improved the early stages of the repair of cartilage and subchondral defects. Furthermore, RCCS provided a dynamic culture microenvironment conducive for cell proliferation, aggregation and differentiation.

LaB6 surface chemistry-reinforced scaffolds for treating bone tumors and bone defects

Bone tumors may lead to osteoporosis. It is of great significance to fabricate functional scaffolds for treating bone tumor, osteoporosis and repairing bone defects. In this study, LaB6 micro-nanoparticles/poly(d,l-lactide)-modified β-tricalcium phosphate scaffolds (TCP-PDLLA-LB) were successfully prepared. The LaB6 surface chemistry-reinforced TCP-PDLLA-LB scaffolds were endowed with the following excellent properties: (1) the enhanced mechanical strength. The TCP-PDLLA-5LB scaffolds possessed higher compression resistant capacity than TCP scaffolds owing to the strong adhesive property of PDLLA that bound the LaB6 micro-nanoparticles and scaffolds tightly; (2) the excellent photothermal performance. TCP-PDLLA-LB scaffolds presented distinct photothermal property because of localized surface plasmon resonance effect of LaB6 micro-nanoparticles when exposed to the near-infrared (NIR) light (wavelength: 808nm) and it was flexibly controllable through changing the quantity of LaB6 micro-nanoparticles, power density of NIR light and environmental humidity; (3) the excellent biological properties in vitro. When culturing with saos-2 bone tumor cells, the TCP-PDLLA-5LB scaffolds effectively killed the saos-2 cells through adjusting power density of NIR light, irradiation duration time of NIR light and irradiation times of NIR light. Additionally, the TCP-PDLLA-5LB scaffolds were able to release bioactive ions which were beneficial to the in vitro osteogenesis of rabbit bone marrow stromal cells (rBMSCs) by supporting the attachment and proliferation of rBMSCs as well as promoting the expressions of osteogenic genes BMP2, RUNX2 and COL 1; and (4) the abilities of effectively ablating bone tumors and supporting bone tissue regeneration in vivo. The bone tumor tissues were significantly ablated and suppressed through hyperthermia due to the existence of LaB6 micro-nanoparticles on the scaffolds. Simultaneously, TCP-PDLLA-5LB scaffolds implanted in bone defects effectively helped new bone formation regardless of NIR light irradiation. In conclusion, LaB6 surface chemistry-reinforced scaffolds possess the dual functions of ablating bone tumor and repairing bone defects, which offers a promising therapy strategy for tumor/disease-related bone tissue engineering.

Oral dosing of pentoxifylline, a pan-phosphodiesterase inhibitor restores bone mass and quality in osteopenic rabbits by an osteogenic mechanism: A comparative study with human parathyroid hormone.

The non-selective phosphodiesterase inhibitor pentoxifylline (PTX) is used for the treatment of intermittent claudication due to artery occlusion. Previous studies in rodents have reported salutary effects of the intraperitoneal administration of PTX in segmental bone defect and fracture healing, as well as stimulation of bone formation. We determined the effect of orally dosed PTX in skeletally mature ovariectomized (OVX) rabbits with osteopenia. The half-maximal effective concentration (EC50) of PTX in rabbit bone marrow stromal cells was 3.07 ± 1.37 nM. The plasma PTX level was 2.05 ± 0.522 nM after a single oral dose of 12.5mg/kg, which was one-sixth of the adult human dose of PTX. Four months of daily oral dosing of PTX at 12.5 mg/kg to osteopenic rabbits completely restored bone mineral density, bone mineral content (BMC), microarchitecture and bone strength to the level of the sham-operated (ovary intact) group. The bone strength to BMC relationship between PTX and sham was similar. The bone restorative effect of PTX was observed in both axial and appendicular bones. In osteopenic rabbits, PTX increased serum amino-terminal propeptide, mineralized nodule formation by stromal cells and osteogenic gene expression in bone. PTX reversed decreased calcium weight percentage and poor crystal packing found in osteopenic rabbits. Furthermore, similar to parathyroid hormone (PTH), PTX had no effect on bone resorption. Taken together, our data show that PTX completely restored bone mass, bone strength and bone mineral properties by an anabolic mechanism. PTX has the potential to become an oral osteogenic drug for the treatment of post-menopausal osteoporosis.

Micro/Nanometer‐Structured Scaffolds for Regeneration of Both Cartilage and Subchondral Bone

AbstractTreatment of osteochondral defects remains a great challenge in clinical practice because cartilage and subchondral bone possess significantly different physiological properties. In this study, the controlled surface micro/nanometer structure of bioactive scaffolds in a combination of biomaterial chemistry is harnessed to address this issue. Model bioactive biomaterials, bredigite (BRT) scaffolds, with controlled surface micro/nanostructure are successfully fabricated by combining 3D printing with a hydrothermal process. It is found that the growth of micro/nano–calcium phosphate crystals on the surface of BRT scaffolds notably enhances their compressive strength by healing the microcracks on the strut surface. The micro/nanostructured surface distinctly facilitates the spread and differentiation of chondrocytes by activating integrin αvb1 and α5b1 heterodimers, regulates cell morphology, and promotes osteogenic differentiation of rabbit bone marrow stromal cells (rBMSCs) through the synergetic effect of integrin α5b1 and RhoA, in which the microrod surface demonstrates the highest stimulatory effect on the differentiation of chondrocytes and rBMSCs. The in vivo study shows that the micro/nanostructured surface of the 3D printed scaffolds obviously promotes the regeneration of both cartilage and subchondral bone tissues. This study suggests that the construction of controlled micro/nanostructured surface in porous 3D scaffolds offers a smart strategy to induce bilineage bioactivities for osteochondral regeneration.

Sr- and Si-containing bioceramic stimulate in vitro osteogenesis

To develop composite bioactive bioceramics for bone tissue engineering, Sr5(PO4)2SiO4 (SrPS) bioceramics that containing bioactive Si and Sr ions were successfully prepared by compression molding in the present study. Cell proliferation and molecular biology actions were studied using the rabbit bone marrow stromal cells (rBMSCs) to evaluate the biological properties of this novel bioceramic. The results showed that comparing with traditional β-tricalcium phosphate (β-TCP), the prepared SrPS bioceramics presented satisfied cytocompatibility and enhanced cell proliferation. In addition, the expression of the bone-related gene bone morphorgenetic protein 2 (BMP2) and osteocalcin (OCN) of rBMSCs was also improved. These results demonstrated that the prepared SrPS bioceramics could stimulate osteogenic in vitro, demonstrating that they might have bright potential for being used as bone repair material.

Pore size directs bone marrow stromal cell fate and tissue regeneration in nanofibrous macroporous scaffolds by mediating vascularization

In the U.S., 30% of adults suffer joint pain, most commonly in the knee, which severely limits mobility and is often attributed to injury of cartilage and underlying bone in the joint. Current treatment methods such as microfracture result in less resilient fibrocartilage with eventual failure; autografting can cause donor site morbidity and poor integration. To overcome drawbacks in treatment, tissue engineers can design cell-instructive biomimetic scaffolds using biocompatible materials as alternate therapies for osteochondral defects. Nanofibrous poly (l-lactic acid) (PLLA) scaffolds of uniform, spherical, interconnected and well-defined pore sizes that are fabricated using a thermally-induced phase separation and sugar porogen template method create an extracellular matrix-like environment which facilitates cell adhesion and proliferation. Herein we report that chondrogenesis and endochondral ossification of rabbit and human bone marrow stromal cells (BMSCs) can be controlled by scaffold pore architecture, particularly pore size. Small-pore scaffolds support enhanced chondrogenic differentiation in vitro and cartilage formation in vivo compared to large-pore scaffolds. Endochondral ossification is prevented in scaffolds with very small pore sizes; pore interconnectivity is critical to promote capillary ingrowth for mature bone formation. These results provide a novel strategy to control tissue regenerative processes by tunable architecture of macroporous nanofibrous scaffolds. Statement of significanceProgress in understanding the relationship between cell fate and architectural features of tissue engineering scaffolds is critical for engineering physiologically functional tissues. Sugar porogen template scaffolds have uniform, spherical, highly interconnected macropores. Tunable pore-size guides the fate of bone marrow stromal cells (BMSCs) towards chondrogenesis and endochondral ossification, and is a critical design parameter to mediate neotissue vascularization. Preventing vascularization favors a chondrogenic cell fate while allowing vascularization results in endochondral ossification and mineralized bone formation. These results provide a novel strategy to control tissue regenerative processes by tunable architecture of macroporous nanofibrous scaffolds.

Effects of lentiviral transfection containing bFGF gene on the biological characteristics of rabbit BMSCs.

To investigate the effect of lentiviral transfection containing bFGF gene on the biological characteristics of bone marrow stromal cells (BMSCs). BMSCs were obtained by density gradient centrifugation and adherence screening. The bFGF gene was transfected into BMSCs by lentiviral vector and divided into bFGF transfection group, empty virus group, and untransfected group according to the transfection conditions. After transfection, the morphology, expression of bFGF mRNA and protein, cell proliferation, cell cycle, and alkaline phosphatase (ALP) activity were observed in three groups of cells. High density BMSCs were successfully obtained by density gradient centrifugation and adherence screening. After transfection of BMSCs with bFGF gene, the cell morphology did not change significantly, while the expression of bFGF mRNA and protein were significantly increased, the cell proliferation curve shifted upward, the proportion of proliferating cells increased, and the activity of ALP was significantly enhanced. Compared with empty virus group and untransfected group, there was significant difference (P < 0.05). The rabbit bFGF gene was successfully introduced into the BMSCs cultured in vitro by lentiviral vector, and the target gene was stably expressed. And the expression of bFGF can promote the proliferation and osteogenic differentiation of BMSCs.

Evaluation of an artificial vertebral body fabricated by a tantalum-coated porous titanium scaffold for lumbar vertebral defect repair in rabbits

Tantalum (Ta)-coated porous Ti-6A1-4V scaffolds have better bioactivity than Ti-6A1-4V scaffolds; however, their bioperformance as an artificial vertebral body (AVB) is unknown. In the present study, we combined a Ta-coated Ti-6A1-4V scaffold with rabbit bone marrow stromal cells (BMSCs) for tissue-engineered AVB (TEAVB) construction and evaluated the healing and fusion efficacy of this scaffold in lumbar vertebral defects after corpectomy in rabbits. The results showed that BMSCs on the surface of the Ta-coated Ti scaffolds proliferated better than BMSCs on Ti scaffolds. Histomorphometry showed better bone formation when using Ta-coated TEAVBs than that with Ti TEAVBs at both 8 and 12 weeks after implantation. In addition, the vertical and rotational stiffness results showed that, compared with uncoated TEAVBs, Ta-coated TEAVBs enhanced rabbit lumbar vertebral defect repair. Our findings demonstrate that Ta-coated TEAVBs have better healing and fusion efficacy than Ti TEAVBs in rabbit lumbar vertebral defects, which indicates their good prospects for clinical application.

A bifunctional scaffold with CuFeSe2 nanocrystals for tumor therapy and bone reconstruction

Bone tumor is one of major challenging issues clinically. After surgical intervention, a few bone tumor cells still remain around bone defects and then proliferate over days. Fabrication of specific biomaterials with dual functions of bone tumor therapy and bone regeneration is of great significance. In order to achieve this aim, we managed to prepare bioactive glass (BG) scaffolds functionalized by the CuFeSe2 nanocrystals (BG-CFS) by combining 3D printing technique with solvothermal method. During the solvothermal reaction process, CuFeSe2 nanocrystals could in situ grow on the strut surface of BG scaffolds and thus endow BG scaffolds excellent photothermal performance. The photothermal performance of BG-CFS scaffolds could be well regulated through altering the content of CuFeSe2 nanocrystals and laser power density when exposed to the near infrared laser (808 nm). The BG-CFS scaffolds could not only effectively ablate the bone tumor cells (Saos-2 cells) in vitro, but also significantly inhibit bone tumor growth in vivo. Moreover, BG-CFS scaffolds could stimulate osteogenic gene expressions of rabbit bone marrow stromal cells (rBMSCs) and finally facilitate the formation of new bone in the bone defects. Our study, for the first time, combined the photothermal performance of semiconductor CuFeSe2 nanocrystals with the bone-forming activity of bioactive glass scaffolds, which can offer a more extensive horizon for developing novel biomaterials with dual functions of bone tumor therapy and bone regeneration.

Enhanced Cartilaginous Tissue Formation with a Cell Aggregate-Fibrin-Polymer Scaffold Complex.

Cell density is one of the factors required in the preparation of engineered cartilage from mesenchymal stem cells (MSCs). Additionally, it is well known for having a significant role in chemical and physical stimulations when stem cells undergo chondrogenic differentiation. Here, we developed an engineered cartilage with a cell aggregate-hydrogel-polymer scaffold complex capable of inducing the effective regeneration of cartilage tissue similar to natural cartilage while retaining a high mechanical strength, flexibility, and morphology. Cell aggregates were generated by the hanging drop method with rabbit bone marrow stromal cells (BMSCs), and poly (lactide-co-caprolactone) (PLCL) scaffolds were fabricated with 78.3 ± 5.3% porosity and a 300–500 μm pore size with a gel-pressing method. We prepared the cell aggregate-fibrin-poly (lactide-co-caprolactone) (PLCL) scaffold complex, in which the cell aggregates were evenly dispersed in the fibrin, and they were immobilized onto the surface of the polymer scaffold while filling up the pores. To examine the chondrogenic differentiation of seeded BMSCs and the formation of chondral extracellular matrix onto the complexes, they were cultured in vitro or subcutaneously implanted into nude mice for up to eight weeks. The results of the in vitro and in vivo studies revealed that the accumulation of the chondral extracellular matrices was increased on the cell aggregate-fibrin-PLCL scaffold complexes (CAPs) compared to the single cell-fibrin-PLCL scaffold complexes (SCPs). Additionally, we examined whether the mature and well-developed cartilaginous tissues and lacunae structures typical of mature cartilage were evenly distributed in the CAPs. Consequently, the cell aggregates in the hybrid scaffolds of fibrin gels and elastic PLCL scaffolds can induce themselves to differentiate into chondrocytes, maintain their phenotypes, enhance glycosaminoglycan (GAG) production, and improve the quality of cartilaginous tissue formed in vitro and in vivo.

Megakaryocytes Enhance Mesenchymal Stromal Cells Proliferation and Inhibit Differentiation.

Megakaryocytes (MKs) can induce proliferation of calvarial osteoblasts [Ciovacco et al., 2009], but this same phenomenon has not been reported for bone marrow stromal populations from long bones. Bone marrow contains several types of progenitor cells which can be induced to differentiate into multiple cell types. Herein, we examined mesenchymal stromal cell proliferation and osteoblastic differentiation when rabbit or mouse MK were cultured with i) rabbit bone marrow stromal cells, ii) rabbit dental pulp stromal cells, or iii) mouse bone marrow stromal cells. Our results demonstrated that rabbit and mouse stromal cells co-cultured with rabbit MK or mouse MK, have significant increases in proliferation on day 7 by 52%, 46%, and 24%, respectively, compared to cultures without MK. Conversely, alkaline phosphatase (ALP) activity was lower at various time points in these cells when cultures contain MK. Similarly, calcium deposition observed at day 14 rabbit bone marrow and dental pulp stromal cells and day 21 mouse bone marrow stromal cells was 63%, 69%, and 30% lower respectively, when co-cultured with MK. Gene expression studies reveal transcriptional changes broadly consistent with increased proliferation and decreased differentiation. Transcript levels of c-fos (associated with cell proliferation) trended higher after 3, 7, and 14 days in culture. Also, expression of alkaline phosphatase, osteonectin, osterix, and osteopontin, which are markers for osteoblast differentiation, showed MK-induced decreases in a cell type and time dependent manner. Taken together, these data suggest that MK play a role in stromal cell proliferation and differentiation, from multiple sites/locations in multiple species. This article is protected by copyright. All rights reserved.

3D-printed bioceramic scaffolds with antibacterial and osteogenic activity

Bacterial infection poses a significant risk with the wide application of bone graft materials. Designing bone grafts with good antibacterial performance and excellent bone-forming activity is of particular significance for bone tissue engineering. In our study, a 3D printing method was used to prepare β-tricalcium phosphate (β-TCP) bioceramic scaffolds. Silver (Ag) nanoparticles were uniformly dispersed on graphene oxide (GO) to form a homogeneous nanocomposite (named Ag@GO) with different Ag-to-graphene oxide mass ratios, with this being synthesized via the liquid chemical reduction approach. Ag@GO nanocomposites were successfully modified on the β-TCP scaffolds by a simple soaking method to achieve bifunctional biomaterials with antibacterial and osteogenic activity. The prepared scaffolds possessed a connected network with triangle pore morphology and the surfaces of the β-TCP scaffolds were uniformly modified by the Ag@GO nanocomposite layers. The Ag content in the scaffolds was controlled by changing the coating times and concentration of the Ag@GO nanocomposites. The antibacterial activity of the scaffolds was assessed with Gram-negative bacteria (Escherichia coli, E. coli). The results demonstrated that the scaffolds with Ag@GO nanocomposites presented excellent antibacterial activity. In addition, the scaffolds coated with Ag@GO nanocomposites conspicuously accelerated the osteogenic differentiation of rabbit bone marrow stromal cells by improving their alkaline phosphatase activity and bone-related gene expression (osteopontin, runt-related transcription factor 2, osteocalcin and bone sialoprotein). This study demonstrates that bifunctional scaffolds with a combination of antibacterial and osteogenic activity can be achieved for the reconstruction of large-bone defects while preventing or treating infections.

Biomimetic tendon extracellular matrix composite gradient scaffold enhances ligament-to-bone junction reconstruction.

The native transitional region consists of several distinct yet contiguous tissue regions, composed of soft tissue, non-calcified fibrocartilage, calcified fibrocartilage, and bone. A stratified graft whose phases are interconnected with each other is essential for supporting the formation of functionally continuous multi-tissue regions. Various techniques have been attempted to improve adherence of the ligament/tendon graft to bone, including utilization of stem cells, growth factors and biomaterials, but these methods are often inadequate at recapitulating the complex structure-function relationships at native tissue interfaces. Here, we developed an easily-fabricated and effective biomimetic composite to promote the regeneration of ligament-bone junction by physically modifying the tendon extracellular matrix (ECM) into a Random-Aligned-Random composite using ultrasound treatment. The modified ECM enhanced expression of chondrogenesis and osteogenesis-associated epigenetic genes expression in vitro. In the rabbit anterior crucial ligament reconstruction model in vivo, results showed that the modified Random-Aligned-Random composite enhances the bone and fibrocartilage formation in the interface, proving to be more efficient than the unmodified tendon ECM. Therefore, these results demonstrated that the biomimetic Random-Aligned-Random composite could be a promising scaffold for ligament/tendon-bone junction repair.

Mesoporous Bioactive Glass Nanolayer‐Modified Zirconia Coatings on Ti‐6Al‐4V with Improved In Vitro Bioactivity

The bioactivity of coatings on alloy implants plays critical roles in the fast osteointegration and maintenance of a long‐term life span of the implants. The aim of this study is to incorporate nanopores and bioactive components into the plasma‐sprayed coatings by constructing nanopores and bioactive elements on the surface of coatings and further improve their in vitro bone‐forming activity. In this study, mesoporous bioactive glasses (MBG) were used for modifying the surface of ZrO2 coatings on Ti‐6Al‐4V by spin‐coating methods. The result shows that MBG nanolayer has been successfully coated on the surface of ZrO2 coatings. The MBG‐modified ZrO2 coatings have improved apatite‐mineralization ability and stable bonding strength. In addition, the attachment, proliferation, alkaline phosphate activity, and bone‐related gene expression of rabbit bone marrow stromal cells on MBG‐ZrO2 coating were also enhanced as compared with conventional bioactive glass‐modified ZrO2 coatings and pure ZrO2 coatings. The results indicated that MBG‐modified ZrO2 coatings on Ti alloy are promising for orthopedic application.

Repair of rabbit cartilage defect based on the fusion of rabbit bone marrow stromal cells and Nano-HA/PLLA composite material

Objective To assess the effect of the fusion of rabbit bone marrow stromal cells (rBMSCs) and Nano-hydroxyapatite/poly (l-lactic acid) (Nano-HA/PLLA) in repairing the rabbit knee joint with full-thickness cartilage defect. Method The rBMSCs were isolated and cultured in vitro, and the third generation of rBMSCs was co-cultured with the Nano-HA/PLLA to construct the tissue-engineered cartilage (TEC). Eighteen New Zealand white rabbits were selected and randomly divided into three groups, namely, TEC group, Nano-HA/PLLA group, and control group. A cartilage defect model with the diameter of 4.5 mm and depth of 5 mm was constructed on the articular surface of medial malleolus of rabbit femur. General observation, histological observation, and Wakitani’s histological scoring were conducted in the 12th and 24th week postoperatively. Results The results of TEC group indicated that new cartilage tissue was formed on the defect site and subchondral bone achieved physiological integration basically. Histological and immunohistochemical analyses indicated the generation of massive extracellular matrix. In contrast, limited regeneration and reconstruction of cartilage was achieved in the Nano-HA/PLLA group and control group, with a significant difference from the TEC group (p < 0.05). Moreover, the effect of cartilage repair was positively correlated with time. Conclusion The porous Nano-HA/PLLA combined with BMSCs promoted the repair of weight-bearing bone of adult rabbit’s knee joint with cartilage defect.