Damaged Bone Tissue Research Articles

Biomimetic fabrication of icariin loaded nano hydroxyapatite reinforced bioactive porous scaffolds for bone regeneration

Biomimetic scaffolds have been a growing demand in bone tissue engineering. Owing to the performance shortcomings of single natural or synthetic polymer, nano hydroxyapatite reinforced hybrid scaffolds loading with icariin (icariin-loaded nHAP/CMCS/PLGA) were biomimetically fabricated by emulsion template method combining organic/inorganic hybrid technology. The scaffold successfully combined insoluble polymers between water-soluble carboxymethyl chitosan (CMCS) and oil-soluble poly(lactide-co-glycolide) (PLGA). In vitro physicochemical properties and cytocompatibility showed that the scaffolds with similar topological structure to the nature bone, and the incorporation of nHAP and icariin not only improved the mechanical properties and in vitro bioactivity, but also accelerated the repair of the damaged bone tissue. In vivo osteogenesis showed good biocompatibility with the scaffolds, especially the 3.0 wt% nHAP/CMCS/PLGA scaffold (S3) and icariin loaded 3.0 wt% nHAP/CMCS/PLGA (I-S3) scaffold, they effectively promoted the adhesion, proliferation and differentiation of the osteoblast. In conclusion, the icariin loaded nHAP/CMCS/PLGA scaffolds fabricated by emulsion template and organic/inorganic hybrid technology holds great potential and provides a unique strategy for bone repair and regeneration.

Inorganic-salt coprecipitation synthesis, fluoride-doping, bioactivity and physiological pH buffering evaluations of bredigite

Bredigite (Ca7MgSi4O16), with suitable bioactivity, biodegradation, biocompatibility and mechanical properties, is a promising candidate for the repair and regeneration of damaged bone tissues. In this research, for the first time, bredigite was synthesized by a facile and inexpensive coprecipitation method using inorganic salt precursors, followed by calcination at 1200 °C. Additionally, 0.5 mol% fluoride was successfully doped into the structure without the formation of any second phases. X-ray diffraction and Fourier-transform infrared spectroscopy confirmed the formation of single-phase orthorhombic bredigite in the samples and the incorporation of fluoride in the doped sample, respectively. Both the undoped and doped samples exhibited apatite-formation ability in terms of the precipitation of hydroxycarbonate apatite when exposed to a simulated physiochemical medium, with an increase in this characteristic as a result of fluoride doping. The addition of fluoride also lowered and buffered the pH value of the medium, where the enhancement of this parameter is due to the fast bioresorption of bredigite affecting disadvantageously biocompatibility.

Phosphorylated Chitosan Hydrogels Inducing Osteogenic Differentiation of Osteoblasts via JNK and p38 Signaling Pathways.

Phosphorous-containing biopolymers have been applied to expedite the regeneration of damaged bone tissue by stimulating the function of phosphorous groups in natural bones. However, the underlying mechanism of phosphorous-containing biopolymers in promoting osteogenic differentiation is unclarified. Herein, we synthesized phosphorylated chitosan hydrogels by incorporating phosphocreatine into chitosan molecular chains under mild conditions. The introduction of phosphate groups improved properties of protein adsorption and calcium deposition without affecting the morphology of hydrogels. Our results showed that phosphorylated chitosan hydrogels could not only promote alkaline phosphatase activity and mineralization but also upregulate the expression of osteogenic-related genes and proteins. Meanwhile, application of c-Jun N-terminal kinase inhibitor SP600125 and p38 mitogen-activated protein kinase inhibitor SB203580 repressed the expression of osteogenic-related markers in gene and protein levels. To the best of our knowledge, it is reported for the first time that phosphorous-containing biopolymers promote osteogenic differentiation of osteoblasts via JNK and p38 signaling pathways.

Applications of Nanocellulose/Nanocarbon Composites: Focus on Biotechnology and Medicine

Nanocellulose/nanocarbon composites are newly emerging smart hybrid materials containing cellulose nanoparticles, such as nanofibrils and nanocrystals, and carbon nanoparticles, such as “classical” carbon allotropes (fullerenes, graphene, nanotubes and nanodiamonds), or other carbon nanostructures (carbon nanofibers, carbon quantum dots, activated carbon and carbon black). The nanocellulose component acts as a dispersing agent and homogeneously distributes the carbon nanoparticles in an aqueous environment. Nanocellulose/nanocarbon composites can be prepared with many advantageous properties, such as high mechanical strength, flexibility, stretchability, tunable thermal and electrical conductivity, tunable optical transparency, photodynamic and photothermal activity, nanoporous character and high adsorption capacity. They are therefore promising for a wide range of industrial applications, such as energy generation, storage and conversion, water purification, food packaging, construction of fire retardants and shape memory devices. They also hold great promise for biomedical applications, such as radical scavenging, photodynamic and photothermal therapy of tumors and microbial infections, drug delivery, biosensorics, isolation of various biomolecules, electrical stimulation of damaged tissues (e.g., cardiac, neural), neural and bone tissue engineering, engineering of blood vessels and advanced wound dressing, e.g., with antimicrobial and antitumor activity. However, the potential cytotoxicity and immunogenicity of the composites and their components must also be taken into account.

Preparation and Characterization of Surface Heat Sintered Nanohydroxyapatite and Nanowhitlockite Embedded Poly (Lactic-co-glycolic Acid) Microsphere Bone Graft Scaffolds: In Vitro and in Vivo Studies.

In the context of using bone graft materials to restore and improve the function of damaged bone tissues, macroporous biodegradable composite bone graft scaffolds have osteoinductive properties that allow them to provide a suitable environment for bone regeneration. Hydroxyapatite (HAP) and whitlockite (WLKT) are the two major components of hard tissues such as bone and teeth. Because of their biocompatibility and osteoinductivity, we synthesized HAP (nHAP) and WLKT nanoparticles (nWLKT) by using the chemical precipitation method. The nanoparticles were separately incorporated within poly (lactic-co-glycolic acid) (PLGA) microspheres. Following this, the composite microspheres were converted to macroporous bone grafts with sufficient mechanical strength in pin or screw shape through surface sintering. We characterized physico-chemical and mechanical properties of the nanoparticles and composites. The biocompatibility of the grafts was further tested through in vitro cell adhesion and proliferation studies using rabbit bone marrow stem cells. The ability to promote osteogenic differentiation was tested through alkaline phosphate activity and immunofluorescence staining of bone marker proteins. For in vivo study, the bone pins were implanted in tibia bone defects in rabbits to compare the bone regeneration ability though H&E, Masson’s trichrome and immunohistochemical staining. The results revealed similar physico-chemical characteristics and cellular response of PLGA/nHAP and PLGA/nWLKT scaffolds but the latter is associated with higher osteogenic potential towards BMSCs, pointing out the possibility to use this ceramic nanoparticle to prepare a sintered composite microsphere scaffold for potential bone grafts and tissue engineered implants.

Experimental Investigation of Mechanical Behavior in 3D Printed PLA Triply Periodic Minimal Surface Structure for Orthopedics

This project is related to the design, fabrication and characterization of scaffold structures of different structure Using Polylactic Acid (PLA) filament, the micro bone structures are manufactured by Fused Deposition Modeling (FDM). Such morphology is chosen for its good strength, high porosity leading to good nutrient and waste diffusion, and favorable mechanical properties. Load vs Displacement values are obtained by taking compression tests for each as an overall outcome of the research, microstructure with better mechanical properties to replace the damaged bone tissues is identified.

Morphometry Results of Formed Osteodefects When Using Nanocrystalline CeO2 in the Early Stages of Regeneration.

This paper studies of the use of nanocrystalline cerium dioxide with artificially formed bone tissue defects. The results of morphometry confirmed the antialterative effect in the early stages of the reparative process of damaged bone tissue. When using calcium hydroxide with nanodispersed cerium dioxide, the nature of osteogenesis should be characterized as activated. In case of damage to the dentin of the roots of the teeth, dentinogenesis in presence of CeO2 occurs with the formation of a combined dentin and bone regenerates. Little or no studies of dentinogenesis in presence of CeO2 were performed by other researchers.

PDGFBB-modified stem cells from apical papilla and thermosensitive hydrogel scaffolds induced bone regeneration

Bone defects caused by cancer surgery or trauma have a strong negative impact on human health. Treatment with cell and material-based complexes provides an alternative strategy for the regeneration of damaged bone tissue. The good physical properties and suitable biodegradability of a thermosensitive hydrogel has been shown to act as a valuable scaffold. Platelet derived growth factor BB (PDGFBB) is mainly secreted by platelets and promotes the migration and angiogenesis of mesenchymal stem cells (MSCs). Although PDGFBB is known to indirectly enhance bone repair in vivo, the effects of PDGFBB on stem cells from apical papilla (SCAPs) require further investigation. In our study, the proliferation of cells was investigated by the cell counting kit-8 and live/dead staining methods. The results indicated that PDGFBB promoted the proliferation of SCAPs. Real-time polymerase chain reaction and Western blot experiments were used to detect osteogenic genes and proteins. Moreover, calvarial defects were created in Sprague-Dawley rats and different complexes implanted. The results shown by micro-CT and hematoxylin and eosin analysis demonstrated that the hydrogel combined with lentiviral supernatant-green fluorescent protein-PDGFBB significantly improved new bone formation and mineralization compared with the other three groups. In summary, our research showed that a thermosensitive hydrogel can be used as a scaffold for 3D cell culture, and PDGFBB gene-modified SCAPs can improve bone formation in calvarial defects.

Strategies towards Orthopaedic Tissue Engineered Graft Generation: Current Scenario and Application

Even though degradation and damage to bone and cartilage tissue can be resolved naturally, but there is a great challenge to regenerate functional tissue due to multiple pathological conditions. To treat the diseased/ damaged bone and cartilage tissue as well as to improve or maintain its natural functions and structure, there are different strategies being developed for repair and regeneration of these tissues. Various innovative researches lead to remarkable improvement in clinical outcome of defective bone and cartilage treatments. Biomaterial based scaffolds which are capable of supporting cell growth and applied for replacement of tissue in vivo for both bone and cartilage. The review also delineates about the tissue engineering bioreactors for the recreation of frameworks to recellularise the graft in vitro by presenting them to physiologically significant mechanical or potentially hydrodynamic stimulation condition. This review summarizes and discusses the strategies for regeneration and repair of bone and cartilage tissue, current scenario and application.

Aligned multi-walled carbon nanotubes with nanohydroxyapatite in a 3D printed polycaprolactone scaffold stimulates osteogenic differentiation.

The development of highly biomimetic scaffolds in terms of composition and structures, to repair or replace damaged bone tissues, is particularly relevant for tissue engineering. This paper investigates a 3D printed porous scaffold containing aligned multi-walled carbon nanotubes (MWCNTs) and nano-hydroxyapatite (nHA), mimicking the natural bone tissue from the nanoscale to macroscale level. MWCNTs with similar dimensions as collagen fibres are coupled with nHA and mixed within a polycaprolactone (PCL) matrix to produce scaffolds using a screw-assisted extrusion-based additive manufacturing system. Scaffolds with different material compositions were extensively characterised from morphological, mechanical and biological points of views. Transmission electron microscopy and polarised Raman spectroscopy confirm the presence of aligned MWCNTs within the printed filaments. The PCL/HA/MWCNTs scaffold are similar to the nanostructure of native bone and shows overall increased mechanical properties, cell proliferation, osteogenic differentiation and scaffold mineralisation, indicating a promising approach for bone tissue regeneration.

Additive Manufacturing of Bioactive Poly(trimethylene carbonate)/β-Tricalcium Phosphate Composites for Bone Regeneration.

Implants of bioresorbable materials combined with osteoconductive calcium phosphate ceramics show promising results to replace and repair damaged bone tissue. Here we present additive manufacturing of patient-specific porous scaffolds of poly(trimethylene carbonate) (PTMC) including high amounts of β-tricalcium phosphate (β-TCP). Tensile testing of composite networks showed that addition of β-tricalcium phosphate reinforces the composites significantly. Three-dimensional structures containing up to 60 wt % β-TCP could be built by stereolithography. By lowering the content to 51 wt %, manufacturing of a large-sized patient-specific prototype was possible at high resolution. Closer examination revealed that the created scaffolds contained more β-TCP on the surface of the builds. Stereolithography therefore provides a manufacturing technique where the bioactive agent is directly available for creating an enhanced microenvironment for cell growth. The biocompatibility and bioresorption of PTMC coupled with the osteoconductivity of β-TCP are an important candidate to consider in additive manufacturing of bone regeneration implants.

Inhibitory Effects of N-[2-(4-acetyl-1-piperazinyl) phenyl]-2-(2-chlorophenoxy) acetamide on Osteoclast Differentiation In Vitro via the Downregulation of TRAF6.

Osteoclasts are poly-nuclear cells that resorb mineral components from old or damaged bone tissue. Primary mononuclear cells are activated by receptor activator of nuclear factor kappa-Β ligand (RANKL) and differentiate into large multinucleated cells. Dysregulation of osteoclast differentiation can lead to pathological bone loss and destruction. Many studies have focused on the development of new molecules to regulate RANKL-mediated signaling. In this study, N-[2-(4-acetyl-1-piperazinyl)phenyl]-2-(2-chlorophenoxy) acetamide (PPOA-N-Ac-2-Cl) led to a significant decrease in the formation of multinucleated tartrate-resistant acid phosphatase (TRAP)-positive cells in a dose-dependent manner, without inducing significant cytotoxicity. PPOA-N-Ac-2-Cl affected the expression of osteoclast-specific marker genes, such as TRAF6, c-fos, DC-STAMP, NFATc1, MMP9, CtsK, and TRAP (Acp5), during RANKL-mediated osteoclastogenesis. Moreover, PPOA-N-Ac-2-Cl significantly attenuated the protein levels of CtsK, a critical protease involved in bone resorption. Accordingly, bone resorption activity and F-actin ring formation decreased in the presence of PPOA-N-Ac-2-Cl. In conclusion, this study shows that PPOA-N-Ac-2-Cl acts as an inhibitor of osteoclast differentiation and may serve as a potential candidate agent for the treatment of osteoclast-related bone diseases by virtue of attenuating bone resorption.

Biomechanical behaviours of the bone-implant interface: a review.

In recent decades, cementless implants have been widely used in clinical practice to replace missing organs, to replace damaged or missing bone tissue or to restore joint functionality. However, there remain risks of failure which may have dramatic consequences. The success of an implant depends on its stability, which is determined by the biomechanical properties of the bone-implant interface (BII). The aim of this review article is to provide more insight on the current state of the art concerning the evolution of the biomechanical properties of the BII as a function of the implant's environment. The main characteristics of the BII and the determinants of implant stability are first introduced. Then, the different mechanical methods that have been employed to derive the macroscopic properties of the BII will be described. The experimental multi-modality approaches used to determine the microscopic biomechanical properties of periprosthetic newly formed bone tissue are also reviewed. Eventually, the influence of the implant's properties, in terms of both surface properties and biomaterials, is investigated. A better understanding of the phenomena occurring at the BII will lead to (i) medical devices that help surgeons to determine an implant's stability and (ii) an improvement in the quality of implants.

Collagen-alginate-nano-silica microspheres improved the osteogenic potential of human osteoblast-like MG-63 cells.

Modular bone tissue engineering is touted as an alternative approach to replace the damaged bone tissue. Hydrogel microcapsules could promote therapeutic properties by providing 3D condition and an increased cell-to-cell interaction. We investigated the osteogenic properties of alginate-nano-silica hydrogels enriched with collagen and gelatin on human osteoblast-like MG-63 cells. For encapsulation, cells were divided into three groups; control (alginate+ nano-silica), collagen (alginate + collagen + nano-silica), and gelatin (alginate + gelatin + nano-silica) and expanded for 28 days. Cell survival was determined by trypan blue staining and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. To confirm the osteogenic potential, we measured the alkaline phosphatase activity. Alizarin red S staining was used to reveal the existence of hydroxyapatite and transcription BMP-2, osteocalcin and osteonectin evaluated by the real-time polymerase chain reaction. Collagen substrate caused a reduced swelling ratio compared with the control and gelatin groups (P < 0.05). Compared with other groups, collagen had potential to improve mechanical strength and generate porous membrane structure. The addition of collagen (4-fold) and gelatin (1.5-fold) increased cell proliferation rate compared with the control (P < 0.05). Biochemical analysis and Alizarin red S staining showed that collagen-induced osteogenesis by induction of alkaline phosphatase and matrix mineralization. The expression of osteocalcin and BMP-2 was increased in cells from the collagen group. As a result, the combination of natural polymers collagen and gelatin with alginate + nano-silica can increase the osteogenic potential of human osteoblasts.

Self-assembled artificial cartilage-hydroxyapatite conjugate for combined articular cartilage and subchondral bone repair

Self-assembled artificial cartilage-hydroxyapatite conjugate for combined articular cartilage and subchondral bone repair

Biomechanical properties of 3D-printed bone models

Bone lesions resulting from large traumas or cancer resections can be successfully treated by directly using synthetic materials or in combination with tissue engineering methods (hybrid). Synthetic or hybrid materials combined with bone tissue’s natural ability for regeneration and biological adaptation to the directions of loading, allow for full recovery of its biological functions.Increasing interest in new production methods or various types of regenerative membranes and shaped scaffolds means that methods such as additive manufacturing can significantly accelerate the preparation of constructs used in the further biological adaptation of natural tissue. The porosity that allows not only ingrowth of the natural tissue, but also the ability of the synthetic material to transfer loadings in the skeletal system during the regeneration interval, will have a significant impact on regenerative capacities. This work presents the results of preliminary analyzes of bone models in the field of mechanical strength for monotonically and cyclically loading conditions. The determined material constants, such as ultimate tensile strength, Young modulus, and toughness or fatigue life, can be used in numerical simulations of new membranes for the regeneration of damaged bone tissue.

A Biocompatible, Simvastatin-Loaded, Bone-Targeting Lipid Nanocarrier: Breaking the 'Traditional Shackle' to Treat Osteoporosis More Effectively

Most of the previous research on osteoporosis has focused on inhibiting the activity of osteoclasts and not on repairing damaged bone tissue. Recent studies have indicated the potential efficacy of simvastatin (SIM) for osteoporosis. The most important reason to focus on SIM is that it can break the traditional shackle of osteoporosis therapy, which has been focused on inhibiting osteoclast activity, and instead treat osteoporosis by promoting osteoblast differentiation and mineralization through the bone morphogenetic proteins (BMP)-Smad signaling pathway, opening up a new avenue for osteoporosis treatment. However, due to poor water solubility, SIM has lower bioavailability, and less bone tissue distribution is observed. Herein, novel lipid nanoparticles (LNPs) delivering SIM (SIM/LNPs) for osteoporosis therapy were developed with aspartic oligopeptide (ASPn, here ASP6)-based bone-targeting moieties grafted to the nanoparticles (SIM/ASP6-LNPs) in an attempt to increase the concentration of SIM in bones with a relatively low dose to minimize adverse effects. In vivo experiments indicated that the ASP6-LNPs exhibited ideal bone-targeting characteristics, and in vitro cell evaluation experiments showed LNPs have good biocompatibility with the MC3T3-E1cells. The cell mineralization experiment revealed that the SIM-loaded LNPs induced osteoblast differentiation and the formation of mineralized nodules in MC3T3-E1 cells, achieving the same efficacy as that of SIM. Pharmacodynamic experiments revealed that SIM/ASP6-LNPs improved the efficacy of SIM on the recovery of bone mineral density when compared to SIM/LNPs or to SIM alone. Therefore, SIM/ASP6-LNPs may represent a potential bone-targeting drug delivery system (DDS) that contributes to the development of a novel osteoporosis treatment.

Effects of extracorporeal fucosylation of CD44 on the homing ability of rabbit bone marrow mesenchymal stem cells

BackgroundThe aim of the study was to investigate the effects of extracorporeal fucosylation of CD44 on the homing ability of rabbit bone marrow mesenchymal stem cells (BMSCs). MethodsThe rabbit BMSCs were extracorporeal fucosylated using alpha-(1,3)-fucosyltransferase VI (FTVI), then the positive rate of sialyl-LewisX (sLeX) and the binding rate of E-selectin were detected by flow cytometry, as well as the fluid adhesion of rabbit BMSCs were detected by the parallel flow chamber adhesion test. Then BMSCs were constructed to stably express enhanced green fluorescent protein (EGFP) and were injected intravenously into the model rabbits with tibial fractures. After 6 weeks of injection, the levels of stromal cell-derived factor (SDF-1) and monocyte chemoattractant protein-1 (MCP-1) in rabbit serum and damaged bone tissues were detected. The positive rate of EGFP expressions was detected by immunohistochemistry staining. ResultsAfter fucosylation, the positive rate of sLeX and the binding rate of E-selectin were significantly higher than those in the no fucosylated group. The results of fluorescence microscopy showed that BMSCs with stable expression of EGFP were successfully constructed. The results of ELISA and Western Blot showed that the secretion of SDF-1 and MCP-1 and the expression of SDF-1 and MCP-1 protein in BMSCs treatment group processed by fucosylated were significantly higher than those in BMSCs treatment group processed by no fucosylated. The results of immunohistochemical staining showed that the positive rate of EGFP expression was also significantly increased, which indicated that the BMSCs at the injured bone tissues were significantly increased and helpful in the repair of bone injury. ConclusionsExtracorporeal fucosylation of CD44 molecules can significantly enhance the homing ability of rabbit BMSCs, which may be achieved by SDF-1 and MCP-1 regulation.

Role of the Complement System in the Response to Orthopedic Biomaterials.

Various synthetic biomaterials are used to replace lost or damaged bone tissue that, more or less successfully, osseointegrate into the bone environment. Almost all biomaterials used in orthopedic medicine activate the host-immune system to a certain degree. The complement system, which is a crucial arm of innate immunity, is rapidly activated by an implanted foreign material into the human body, and it is intensely studied regarding blood-contacting medical devices. In contrast, much less is known regarding the role of the complement system in response to implanted bone biomaterials. However, given the increasing knowledge of the complement regulation of bone homeostasis, regeneration, and inflammation, complement involvement in the immune response following biomaterial implantation into bone appears very likely. Moreover, bone cells can produce complement factors and are target cells of activated complement. Therefore, new bone formation or bone resorption around the implant area might be greatly influenced by the complement system. This review aims to summarize the current knowledge on biomaterial-mediated complement activation, with a focus on materials primarily used in orthopedic medicine. In addition, methods to modify the interactions between the complement system and bone biomaterials are discussed, which might favor osseointegration and improve the functionality of the device.

Genome-Wide DNA Methylation Analysis during Osteogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells.

Bone marrow mesenchymal stem cells (BMSCs) nowadays are regarded as promising candidates in cell-based therapy for the regeneration of damaged bone tissues that are either incurable or intractable due to the insufficiency of current therapies. Recent studies suggest that BMSCs differentiate into osteoblasts, and that this differentiation is regulated by some specific patterns of epigenetic modifications, such as DNA methylation. However, the potential role of DNA methylation modification in BMSC osteogenic differentiation is unclear. In this study, we performed a genome-wide study of DNA methylation between the noninduced and induced osteogenic differentiation of BMSCs at day 7. We found that the majority of cytosines in a CpG context were methylated in induced BMSCs. Our results also revealed that, along with the induced osteogenic differentiation in BMSCs, the average genomic methylation levels and CpG methylation in transcriptional factor regions (TFs) were increased, the CpG methylation level of various genomic elements was mainly in the medium-high methylation section, and CpG methylation levels in the repeat element had highly methylated levels. The GO analysis of differentially methylated region- (DMR-) associated genes (DMGs) showed that GO terms, including cytoskeletal protein binding (included in Molecular Function GO terms), skeletal development (included in Biological Process GO terms), mesenchymal cell differentiation (included in Biological Process GO terms), and stem cell differentiation (included in Biological Process), were enriched in the hypermethylated DMGs. Then, the KEGG analysis results showed that the WNT pathway, inositol phosphate metabolism pathway, and cocaine addiction pathway were more correlative with the DMRs during the induced osteogenic differentiation in BMSCs. In conclusion, this study revealed the difference of methylated levels during the noninduced and induced osteogenic differentiation of BMSCs and provided useful information for future works to characterize the important function of epigenetic mechanisms on BMSCs' differentiation.