Optimal ultrasonic treatment frequency and duration parameters were used to detect the pathogenic bacteria of orthopedic implant-associated infection by ultrasonic oscillation.

INTRUDUCTON: The most accurate method for detecting the pathogen of orthopedic implant-associated infections (OIAIs) is sonication fluid (SF). However, the frequency and duration of ultrasound significantly influence the number and activity of microorganisms. Currently, there is no consensus on the selection of these two parameters. Through this study, the choice of these two parameters is clarified. METHODS: We established five ultrasonic groups (40kHz/10min, 40kHz/5min, 40 kHz/1min, 20kHz/5min, and 10kHz/5min) based on previous literature. OIAIs models were then developed and applied to ultrasound group treatment. Subsequently, we evaluated the efficiency of bacteria removal by conducting SEM and crystal violet staining. The number of live bacteria in the SF was determined using plate colony count and live/dead bacteria staining. RESULTS: The results of crystal violet staining revealed that both the 40kHz/5min group and the 40kHz/10min group exhibited a significantly higher bacterial clearance rate compared to the other groups. However, there was no significant difference between the two groups. Additionally, the results of plate colony count and fluorescence staining of live and dead bacteria indicated that the number of live bacteria in the 40kHz/5min SF group was significantly higher than in the other groups. CONCLUSION: 40kHz/5min ultrasound is the most beneficial for the detection of pathogenic bacteria on the surface of orthopedic implants.

Analysis of risk factors and development of a nomogram-based prediction model for defective bony non-union.

Objective: To explore risk factors for defective non-union of bone and develop a nomogram-based prediction model for such an outcome. Methods: This retrospective study analysed the case data of patients with defective bony non-unions who were treated at the authors' hospital between January 2010 and December 2020. Patients were divided into the union and non-union groups according to their Radiographic Union Score for Tibia scores 1 year after surgery. Univariate analysis was performed to assess factors related to demographic characteristics, laboratory investigations, surgery, and trauma in both groups. Subsequently, statistically significant factors were included in the multivariate logistic regression analysis to identify independent risk factors. A nomogram-based prediction model was established using statistically significant variables in the multivariate analysis. The accuracy and stability of the model were evaluated using receiver operating characteristic (ROC) and calibration curves. The clinical applicability of the nomogram model was evaluated using decision curve analysis. Results: In total, 204 patients (171 male, 33 female; mean [±SD] age, 39.75 ± 13.00 years) were included. The mean body mass index was 22.95 ± 3.64 kg/m2. Among the included patients, 29 were smokers, 18 were alcohol drinkers, and 21 had a previous comorbid systemic disease (PCSD). Univariate analysis revealed that age, occupation, PCSD, smoking, drinking, interleukin-6, C-reactive protein (CRP), procalcitonin, alkaline phosphatase, glucose, and uric acid levels; blood calcium ion concentration; and bone defect size (BDS) were correlated with defective bone union (all P < 0.05). Multivariate logistic regression analysis revealed that PCSD, smoking, interleukin-6, CRP, and glucose levels; and BDS were associated with defective bone union (all P < 0.05), and the variables in the multivariate analysis were included in the nomogram-based prediction model. The value of the area under the ROC curve for the predictive model for bone defects was 0.95. Conclusion: PCSD, smoking, interleukin-6, CRP, and glucose levels; and BDS were independent risk factors for defective bony non-union, and the incidence of such non-union was predicted using the nomogram. These findings are important for clinical interventions and decision-making.

[Correlation of expression of silencing information regulator 2 related enzyme 1 and tumor necrosis factor-like weak inducer of apoptosis in articular effusion and knee osteoarthritis].

OBJECTIVE: To analyze the correlation between the expression of silencing information regulator 2 related enzyme 1 (SIRT1), tumor necrosis factor like weak inducer of apoptosis (TWEAK) and knee osteoarthritis. METHODS: Total of 103 patients with knee joint (knee osteoarthritis group) from February 2019 to August 2021 were selected including 40 males and 63 females with an average age of (62.02±6.09) years;according to the modified Mankin score, 103 patients were divided into mild group (Mankin score 1-4 points, 31 cases) and moderate group (Mankin score 5-8 points, 40 cases) and severe group (Mankin score ≥9, 32 cases). Another 105 physical examination volunteers were selected as the control group including 46 males and 59 females with an average age of (62.11±6.34) years old. The levels of SIRT1 and TWEAK in articular effusion and serum were detected in the knee osteoarthritis group, while serum SIRT1 and TWEAK were detected in the control group only. The relationship between SIRT1, TWEAK and the occurrence and disease of knee osteoarthritis were analyzed. RESULTS: Articular cavity fluid TWEAK, serum TWEAK, CRP, IL-6, IL-1ß, white blood cell count and ESR were higher than those in the control group(P<0.05), articular cavity fluid SIRT1 and serum SIRT1 were lower than those in the control group(P<0.05). TWEAK level in the severe group was higher than that in the moderate and mild groups(P<0.05), SIRT1 was lower than that in the moderate and mild groups (P<0.05). The level of SIRT1 in articular cavity effusion was positively correlated with the serum level of SIRT1 (P<0.05), and negatively correlated with CRP, IL-6, IL-1ß, white blood cell count, modified Mankin score and ESR (P<0.05). TWEAK level in articular cavity fluid was positively correlated with serum TWEAK level (P<0.05), C-reactive protein(CRP), interleukin(IL)-6, IL-1ß, white blood cell count, modified Mankin score and erythrocyte sedimentation rate(ESR) (P<0.05). Body mass index, undertaking heavy physical work, and articular cavity fluid TWEAK were risk factors for the occurrence of knee osteoarthritis(P<0.05), and articular cavity fluid SIRT1 was a protective factor for the occurrence of knee arthritis (P<0.05). The area under curve(AUC) of SIRT1 and TWEAK for knee osteoarthritis was 0.641 and 0.653, and the AUC of SIRT1 and TWEAK for knee osteoarthritis was 0.879, which was higher than SIRT1 and TWEAK alone (z=6.105 and 6.225, P<0.05). CONCLUSION: The level of SIRT1 in articular fluid in patients with knee arthritis is decreased and the level of TWEAK is increased. Low SIRT1 and high TWEAK are associated with the onset and exacerbation of knee osteoarthritis.

Enhancement of antibacterial properties and biocompatibility of Ti6Al4V by graphene oxide/strontium nanocomposite electrodepositing.

Ti6Al4V is a widely used orthopedic implant material in clinics. Due to its poor antibacterial properties, surface modification is required to prevent peri-implantation infection. However, chemical linkers used for surface modification have generally been reported to have detrimental effects on cell growth. In this work, by optimizing parameters related to electrodeposition, a composite structural coating with graphene oxide (GO) compact films in the inner layer and 35 nm diameter strontium (Sr) nanoparticles in the outer layer was constructed on the surface of Ti6Al4V without using substance harmful to bone marrow mesenchymal stem cells (BMSCs) growth. The antibacterial properties of Ti6Al4V are enhanced by the controlled release of Sr ions and incomplete masking of the GO surface, showing excellent antibacterial activity against Staphylococcus aureus in bacterial culture assays. The biomimetic GO/Sr coating has a reduced roughness of the implant surface and a water contact angle of 44.1°, improving the adhesion, proliferation and differentiation of BMSCs. Observations of synovial tissue and fluid in the joint in an implantation model of rabbit knee also point to the superior anti-infective properties of the novel GO/Sr coating. In summary, the novel GO/Sr nanocomposite coating on the surface of Ti6Al4V effectively prevents surface colonization of Staphylococcus aureus and eliminates local infections in vitro and in vivo.

Microgroove Cues Guiding Fibrogenesis of Stem Cells via Intracellular Force.

Groove patterns are widely used in material surface modifications. However, the independent role of ditches/ridges in regulating fibrosis of soft tissues is not well-understood, especially the lack of linkage evidence in vitro and in vivo. Herein, two kinds of combinational microgroove chips with the gradient ditch/ridge width were fabricated by photolithography technology, termed R and G groups, respectively. In group R, the ridge width was 1, 5, 10, and 30 µm, with a ditch width of 30 µm; in group G, the groove width was 5, 10, 20, and 30 µm, and the ridge width was 5 µm. The effect of microgrooves on the morphology, proliferation, and expression of fibrous markers of stem cells was systematically investigated in vitro. Moreover, thicknesses of fibrous capsules were evaluated after chips were implanted into the muscular pouches of rats for 5 months. The results show that microgrooves have almost no effect on cell proliferation but significantly modulate the morphology of cells and focal adhesions (FAs) in vitro, as well as fibrosis differentiation. In particular, the differentiation of stem cells is attenuated after the intracellular force caused by stress fibers and FAs is interfered by drugs, such as rotenone and blebbistatin. Histological analysis shows that patterns of high intracellular force can apparently stimulate soft tissue fibrosis in vivo. This study not only reveals the specific rules and mechanisms of ditch/ridge regulating stem cell behaviors but also offers insight into tailoring implant surface patterns to induce controlled soft tissue fibrosis.

A 3D bioprinted nano-laponite hydrogel construct promotes osteogenesis by activating PI3K/AKT signaling pathway.

Development of nano-laponite as bioinks based on cell-loaded hydrogels has recently attracted significant attention for promoting bone defect repairs and regeneration. However, the underlying mechanisms of the positive function of laponite in hydrogel was not fully explored. In this study, the effect of 3D bioprinted nano-laponite hydrogel construct on bone regeneration and the potential mechanism was explored in vitro and in vivo. In vitro analyses showed that the 3D construct protected encapsulated cells from shear stresses during bioprinting, promoted cell growth and cell spreading, and BMSCs at a density of 107/mL exhibited an optimal osteogenesis potential. Osteogenic differentiation and ectopic bone formation of BMSCs encapsulated inside the 3D construct were explored by determination of calcium deposition and x-ray, micro-CT analysis, respectively. RNA sequencing revealed that activation of PI3K/AKT signaling pathway of BMSCs inside the laponite hydrogel significantly upregulated expression of osteogenic related proteins. Expression of osteogenic proteins was significantly downregulated when the PI3K/AKT pathway was inhibited. The 3D bioprinted nano-laponite hydrogel construct exhibited a superior ability for bone regeneration in rat bones with defects compared with groups without laponite as shown by micro-CT and histological examination, while the osteogenesis activity was weakened by applications of a PI3K inhibitor. In summary, the 3D bioprinted nano-laponite hydrogel construct promoted bone osteogenesis by promoting cell proliferation, differentiation through activation of the PI3K/AKT signaling pathway.

Effects of different intensities of intermittent pneumatic soft-tissue compression on bone defect repair.

BACKGROUND: To estimate the effects of different intensities of intermittent pneumatic soft-tissue compression on bone defect repair in an animal model. METHODS: Five mm radial bone defect in length was made in 64 mature New Zealand rabbits and all animals randomly assigned into four groups: Group A (control group without compression), Group B (5-7 kPa intensity), Group C (8-10 kPa intensity) and Group D (11-13 kPa intensity). On the fourth day after surgery, their legs were intermittently pneumatic compressed for 4 weeks. The stimulation lasted 30 min every day and the frequency of compression was 15 Hz. New bone formation in 4 groups was evaluated by gross observation, X-ray, Micro-CT, and histological staining at 2 and 4 weeks after surgery. RESULT: There was more new bony callus in the bone defect in group C than in other groups by gross observation and X-ray radiography at 2 and 4 weeks. The Micro-CT results showed more new bony callus, bone trabecula and higher bone mineral density in group C. Fluorescent labeling results showed the speed of new bone formation in Group C was faster than that in other groups, among which the control group had the slowest speed of new bone formation. The result of histology had shown that the trabeculae in bone callus in group C had a regular form, the trabeculae were wide and had a more become osteoblast around them. CONCLUSION: The intermittent pneumatic soft-tissue compression can accelerate new bone formation of bone defects and the optimal intensity is 8-10 kPa for repairing the rabbit radial bone defect.

Coating CoCrMo Alloy with Graphene Oxide and ε-Poly-L-Lysine Enhances Its Antibacterial and Antibiofilm Properties.

INTRODUCTION: With increases in implant infections, the search for antibacterial and biofilm coatings has become a new interest for orthopaedists and dentists. In recent years, graphene oxide (GO) has been extensively studied for its superior antibacterial properties. However, most of these studies have focused on solutions and there are few antibacterial studies on metal surfaces, especially the surfaces of cobalt-chromium-molybdenum (CoCrMo) alloys. ε-Poly-L-lysine (ε-PLL), as a novel food preservative, has a spectrum of antimicrobial activity; however, its antimicrobial activity after coating an implant surface is not clear. METHODS: In this study, for the first time, a two-step electrodeposition method was used to coat GO and ε-PLL on the surface of a CoCrMo alloy. Its antibacterial and antibiofilm properties against S. aureus and E. coli were then studied. RESULTS: The results show that the formation of bacteria and biofilms on the coating surface was significantly inhibited, GO and ε-PLL composite coatings had the best antibacterial and antibiofilm effects, followed by ε-PLL and GO coatings. In terms of classification, the coatings are anti-adhesive and contact-killing/inhibitory surfaces. In addition to oxidative stress, physical damage to GO and electrostatic osmosis of ε-PLL are the main antibacterial and antibiofilm mechanisms. DISCUSSION: This is the first study that GO and ε-PLL coatings were successfully prepared on the surface of CoCrMo alloy by electrodeposition. It provides a promising new approach to the problem of implant infection in orthopedics and stomatology.

Biological sealing and integration of a fibrinogen-modified titanium alloy with soft and hard tissues in a rat model.

Percutaneous or transcutaneous devices are important and unique, and the corresponding biological sealing at the skin-implant interface is the key to their long-term success. Herein, we investigated the surface modification to enhance biological sealing, using a metal sheet and screw bonded by biomacromolecule fibrinogen mediated via pre-deposited synthetic macromolecule polydopamine (PDA) as a demonstration. We examined the effects of a Ti-6Al-4V titanium alloy modified with fibrinogen (Ti-Fg), PDA (Ti-PDA) or their combination (Ti-PDA-Fg) on the biological sealing and integration with skin and bone tissues. Human epidermal keratinocytes (HaCaT), human foreskin fibroblasts (HFF) and preosteoblasts (MC3T3-E1), which are closely related to percutaneous implants, exhibited better adhesion and spreading on all the three modified sheets compared with the unmodified alloy. After three-week subcutaneous implantation in Sprague-Dawley (SD) rats, the Ti-PDA-Fg sheets could significantly attenuate the soft tissue response and promote angiogenesis compared with other groups. Furthermore, in the model of percutaneous tibial implantation in SD rats, the Ti-PDA-Fg screws dramatically inhibited epithelial downgrowth and promoted new bone formation. Hence, the covalent immobilization of fibrinogen through the precoating of PDA is promising for enhanced biological sealing and osseointegration of metal implants with soft and hard tissues, which is critical for an orthopedic percutaneous medical device.

Antibacterial and antibiofilm properties of graphene and its derivatives.

Infections resulting from bacteria and biofilms have become a huge problem threatening human health. In recent years, the antibacterial and antibiofilm effects of graphene and its derivatives have been extensively studied. However, there continues to be some controversy over whether graphene and its derivatives can resist infection and biofilms. Moreover, the antibacterial mechanism and cytotoxicity of graphene and its derivatives are unclear. In the present review, antibacterial and antibiofilm abilities of graphene and its derivatives in solution, on the surface are reviewed, and their toxicity and possible mechanisms are also reviewed. Furthermore, we propose possible future development directions for graphene and its derivatives in antibacterial and antibiofilm applications.

3D-bioprinted functional and biomimetic hydrogel scaffolds incorporated with nanosilicates to promote bone healing in rat calvarial defect model.

Three-dimensional (3D) bioprinting is an extremely convenient biofabrication technique for creating biomimetic tissue-engineered bone constructs and has promising applications in regenerative medicine. However, existing bioinks have shown low mechanical strength, poor osteoinductive ability, and lacking a suitable microenvironment for laden cells. Nanosilicate (nSi) has shown to be a promising biomaterial, due to its unique properties such as excellent biocompatibility, degrade into nontoxic products, and with osteoinductive properties, which has been used in bone bioprinting. However, the long term bone healing effects and associating risks, if any, of using nSi in tissue engineering bone scaffolds in vivo are unclear and require a more thorough assessment prior to practical use. Hence, a functional and biomimetic nanocomposite bioink composed of rat bone marrow mesenchymal stem cells (rBMSCs), nSi, gelatin and alginate for the 3D bioprinting of tissue-engineered bone constructs is firstly demonstrated, mimicking the structure of extracellular matrix, to create a conducive microenvironment for encapsulated cells. It is shown that the addition of nSi significantly increases the printability and mechanical strength of fabricated human-scale tissue or organ structures (up to 15 mm height) and induces osteogenic differentiation of the encapsulated rBMSCs in the absence of in vitro osteoinductive factors. A systematic in vivo research of the biomimetic nanocomposite bioink scaffolds is further demonstrated in a rat critical-size (8 mm) bone defect-repair model. The in vivo results demonstrate that the 3D bioprinted nanocomposite scaffolds can significantly promote the bone healing of the rat calvarial defects compared to other scaffolds without nSi or cells, and show rarely side effects on the recipients. Given the above advantageous properties, the 3D bioprinted nanocomposite scaffolds can greatly accelerate the bone healing in critical bone defects, thus providing a clinical potential candidate for orthopedic applications.

Zinc Silicate/Nano-Hydroxyapatite/Collagen Scaffolds Promote Angiogenesis and Bone Regeneration via the p38 MAPK Pathway in Activated Monocytes.

Recent studies show that biomaterials are capable of regulating immune responses to induce a favorable osteogenic microenvironment and promote osteogenesis and angiogenesis. In this study, we investigated the effects of zinc silicate/nanohydroxyapatite/collagen (ZS/HA/Col) scaffolds on bone regeneration and angiogenesis and explored the related mechanism. We demonstrate that 10ZS/HA/Col scaffolds significantly enhanced bone regeneration and angiogenesis in vivo compared with HA/Col scaffolds. ZS/HA/Col scaffolds increased tartrate-resistant acid phosphatase (TRAP)-positive cells, nestin-positive bone marrow stromal cells (BMSCs) and CD31-positive neovessels, and expression of osteogenesis (Bmp-2 and Osterix) and angiogenesis-related (Vegf-α and Cd31) genes increased in nascent bone. ZS/HA/Col scaffolds with 10 wt % ZS activated the p38 signaling pathway in monocytes. The monocytes subsequently differentiated into TRAP+ cells and expressed higher levels of the cytokines SDF-1, TGF-ß1, VEGF-α, and PDGF-BB, which recruited BMSCs and endothelial cells (ECs) to the defect areas. Blocking the p38 pathway in monocytes reduced TRAP+ differentiation and cytokine secretion and resulted in a decrease in BMSC and EC homing and angiogenesis. Overall, these findings demonstrate that 10ZS/HA/Col scaffolds modulate monocytes and, thereby, create a favorable osteogenic microenvironment that promotes BMSC migration and differentiation and vessel formation by activating the p38 signaling pathway.

The effect of fluid shear stress on fibroblasts and stem cells on plane and groove topographies.

In this study, we aimed to study the effect of fluid shear stress on fibroblasts and BMSCs on plane and groove topographies. The results showed that 0.6-Hz stress had the greatest influence on the alignment, polarity, migration and adhesion of fibroblasts on plane by increasing the expression of reoriented actin and vinculin; whereas 1.0-Hz stress promoted differentiation of fibroblasts into myofibroblasts by increasing Col-I and α-SMA expression. Interestingly, under the given frequency stress, the groove structure strengthened the above characteristics of fibroblasts beyond adhesion, and promoted differentiation of BMSCs into myofibroblasts. The above results indicate that 0.6 Hz may improve the implant-tissue sealing, while 1.0-Hz stress probably causes the disordered fiber deposition around implants.

Cell-loaded injectable gelatin/alginate/LAPONITE® nanocomposite hydrogel promotes bone healing in a critical-size rat calvarial defect model.

Injectable hydrogels have long been gaining attention in the bone tissue engineering field owing to their ability to mix homogeneously with cells and therapeutic agents, minimally invasive administration, and seamless defect filling. Despite the advantages, the use of injectable hydrogels as cell delivery carriers is currently limited by the challenge of mimicking the natural microenvironment of the loaded cells, promoting cell proliferation, and enhancing bone regeneration. To overcome these problems, we aimed to develop an injectable and in situ-forming nanocomposite hydrogel composed of gelatin, alginate, and LAPONITE® to mimic the architecture and composition of the extracellular matrix. The encapsulated rat bone marrow mesenchymal stem cells (rBMSCs) survived in the nanocomposite hydrogel, and the gel promoted cell proliferation in vitro. Systematic in vivo research of the biomimetic hydrogel with or without cells was conducted in a critical-size (8 mm) rat bone defect model. The in vivo results proved that the hydrogel loaded with rBMSCs significantly promoted bone healing in rat calvarial defects, compared to the hydrogel without cells, and that the hydrogel did not provoked side effects on the recipients. Given these advantageous properties, the developed cell-loaded injectable nanocomposite hydrogel can greatly accelerate the bone healing in critical bone defects, thus providing a clinical potential candidate for orthopedic applications.

Effects of cyclic fluid stress at different frequencies on behaviors of cells incubated on titanium alloy.

The orthopedic external fixation is always in dynamic mechanical environment with the somatic movement. We used a self-designed mini oscillator to simulate this condition by providing the reciprocating cyclic fluid stress, and observed the behavioral responses of fibroblasts implanted on titanium alloy plane to the stress at different frequencies, including 0.2 Hz, 0.6 Hz, and 1.0 Hz. We found that the cell angle, shape index and expression of vinculin were mostly biphasic-dependent with the increase of frequency, with peaks at 0.6 Hz. Whereas the cell area, expression of Col-I and α-SMA were mainly affected by the 1.0 Hz stress. Interestingly, 1.0 Hz stress also promoted Col-I expression of bone marrow mesenchymal stem cells (BMSCs), although it did not increase α-SMA. These results reveal that 0.6 Hz stress improves the alignment, polarity and adherence of fibroblasts on titanium alloy substrates, thus improving the sealing of implants; the 1.0 Hz force activates the differentiation of fibroblasts into myofibroblasts and increases collagen produced by stem cells, which probably cause the formation of fibrous capsules around implants.

Blockade of adrenergic ß-receptor activation through local delivery of propranolol from a 3D collagen/polyvinyl alcohol/hydroxyapatite scaffold promotes bone repair in vivo.

OBJECTIVES: Activation of the sympathetic system and adrenergic ß-receptors following traumatic bone defects negatively impairs bone regeneration. Whether preventing ß-receptor activation could potentially improve bone defect repair is unknown. In this study, we investigated the effect of systematic administration and local delivery of propranolol through composite scaffolds on bone healing. MATERIALS AND METHODS: Collagen/PVA/propranolol/hydroxyapatite（CPPH）composite scaffolds were fabricated with 3D printing technique and characterized by scanning electron microscope (SEM). Micro-CT analysis and bone formation histology were performed to detect new bone formation. Osteogenic differentiation of bone marrow stromal cells (BMSCs) and osteoclastogenesis of bone marrow monocytes cultured with scaffolds extract were performed for further verification. RESULTS: Intraperitoneal injection of propranolol did not significantly improve bone repair, as indicated by micro-CT analysis and bone formation histology. However, CPPH scaffolds exhibited sustained release of propranolol in vitro and significantly enhanced bone regeneration compared with vehicle collagen/PVA/hydroxyapatite (CPH) scaffolds in vivo. Moreover, in vitro experiments indicated the scaffolds containing propranolol promoted the osteogenic differentiation and migration of rat BMSCs and inhibited osteoclastogenesis by preventing ß-receptor activation. CONCLUSIONS: This study demonstrates that local adrenergic ß-receptor blockade can effectively enhance the treatment of bone defects by stimulating osteogenic differentiation, inhibiting osteoclastogenesis and enhancing BMSCs migration.

Salvianolic Acid B-Loaded Chitosan/hydroxyapatite Scaffolds Promotes The Repair Of Segmental Bone Defect By Angiogenesis And Osteogenesis.

BACKGROUND: Salvianolic acid B has been proven as an effective drug to promote osteogenesis and angiogenesis which could be beneficial for bone repair. PURPOSE: The objective of this study was to construct a salvianolic acid B-loaded chitosan/hydroxyapatite (Sal B-CS/HA) bone scaffold with controlled release and effective bioactivity. METHODS: The characteristics, controlled release behavior and bioactivity of Sal B-CS/HA scaffold were evaluated in vitro. The bone repair effect was evaluated in the rabbit radius defect model. RESULTS: The results showed that chemical and physical characteristics of salvianolic acid B and chitosan/hydroxyapatite (CS/HA) material did not obviously change after the drug loading procedure; the drug release of salvianolic acid B was stable and continuous from the Sal B-CS/HA scaffold for 8 weeks in vitro; the biocompatibility of the Sal B-CS/HA was favorable by evaluation of cell morphology and proliferation; the osteogenic and angiogenic bioactivities of the Sal B-CS/HA scaffold were proved to be effective by in vivo and in vitro tests. CONCLUSION: Our results suggest that this salvianolic acid B-loaded bone scaffold has potential to be used for bone defect repair with both osteogenic and angiogenic bioactivities.

Enhancement of surface bioactivity on carbon fiber-reinforced polyether ether ketone via graphene modification.

BACKGROUND AND OBJECTIVE: The modulus of carbon fiber-reinforced polyether ether ketone (CFR-PEEK), a composite containing layers of carbon fiber sheets, can be precisely controlled to match bone. However, CFR-PEEK is biologically inert and cannot promote bone apposition. The objective of this study was to investigate whether graphene modification could enhance the bioactivity of CFR-PEEK. METHODS AND RESULTS: In vitro, the proliferation and differentiation of rat bone marrow stromal cells on scaffolds were quantified via cell-counting kit-8 assay and Western blotting analysis of osteoblast-specific proteins. Graphene modification significantly promoted bone marrow stromal cell proliferation and accelerated induced differentiation into osteogenic lineages compared to cells seeded onto nongraphene-coated CFR-PEEK. An in vivo rabbit extraarticular graft-to-bone healing model was established. At 4, 8, and 12 weeks after surgery, microcomputed tomography analyses and histological observations revealed significantly better microstructural parameters and higher average mineral apposition rates for graphene-modified CFR-PEEK implants than CFR-PEEK implants (P<0.05). van Gieson staining indicated more new bone was formed around graphene-modified CFR-PEEK implants than CFR-PEEK implants. CONCLUSION: Graphene may have considerable potential to enhance the bioactivity and osseointegration of CFR-PEEK implants for clinical applications.

Graphene coating on the surface of CoCrMo alloy enhances the adhesion and proliferation of bone marrow mesenchymal stem cells.

The objective was to investigate whether a graphene coating could improve the surface bioactivity of a cobalt-chromium-molybdenum-based alloy (CoCrMo). Graphene was produced by chemical vapor deposition and transferred to the surface of the CoCrMo alloy using an improved wet transfer approach. The morphology of the samples was observed, and the adhesion force and stabilization of graphene coating were analyzed by a nanoscratch test and ultrasonication test. In an in vitro study, the adhesion and proliferation of bone marrow mesenchymal stem cells (BMSCs) cultured on the samples were quantified via an Alamar Blue assay and cell counting kit-8 (CCK-8) assay. The results showed that it is feasible to apply graphene to modify the surface of a CoCrMo alloy, and the enhancement of the adhesion and proliferation of BMSCs was also shown in the present study. In conclusion, graphene exhibits considerable potential for enhancing the surface bioactivity of CoCrMo alloy.

Nano-biphasic calcium phosphate/polyvinyl alcohol composites with enhanced bioactivity for bone repair via low-temperature three-dimensional printing and loading with platelet-rich fibrin.

BACKGROUND AND AIM: As a newly emerging three-dimensional (3D) printing technology, low-temperature robocasting can be used to fabricate geometrically complex ceramic scaffolds at low temperatures. Here, we aimed to fabricate 3D printed ceramic scaffolds composed of nano-biphasic calcium phosphate (BCP), polyvinyl alcohol (PVA), and platelet-rich fibrin (PRF) at a low temperature without the addition of toxic chemicals. METHODS: Corresponding nonprinted scaffolds were prepared using a freeze-drying method. Compared with the nonprinted scaffolds, the printed scaffolds had specific shapes and well-connected internal structures. RESULTS: The incorporation of PRF enabled both the sustained release of bioactive factors from the scaffolds and improved biocompatibility and biological activity toward bone marrow-derived mesenchymal stem cells (BMSCs) in vitro. Additionally, the printed BCP/PVA/PRF scaffolds promoted significantly better BMSC adhesion, proliferation, and osteogenic differentiation in vitro than the printed BCP/PVA scaffolds. In vivo, the printed BCP/PVA/PRF scaffolds induced a greater extent of appropriate bone formation than the printed BCP/PVA scaffolds and nonprinted scaffolds in a critical-size segmental bone defect model in rabbits. CONCLUSION: These experiments indicate that low-temperature robocasting could potentially be used to fabricate 3D printed BCP/PVA/PRF scaffolds with desired shapes and internal structures and incorporated bioactive factors to enhance the repair of segmental bone defects.