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BACKGROUND:Metal ions play an important role in the human body.With the progress of material synthesis and processing technology,a variety of metal ions that can be used in bone tissue engineering have been developed,such as magnesium(Mg2+),zinc(Zn2+),manganese(Mn2+),strontium(Sr2+),and copper(Cu2+). OBJECTIVE:To summarize the research progress and development direction of metal ions in bone tissue engineering. METHODS:The literature collected by CNKI,PubMed and WanFang databases from 2014 to 2022 was retrieved.The Chinese and English key words were"metal ions,bone tissue engineering,osteogenic activity,magnesium ions,zinc ions,manganese ions,strontium ions,copper ions,calcium ions,lithium ions,cobalt ions". RESULTS AND CONCLUSION:Different metal ions will be released to varying degrees after the materials are implanted into the body,which can change the tissue microenvironment,thus improving the ability of materials to form blood vessels and bones.Compared with growth factors,metal ions are easier to control the release rate,have lower cost,and can also improve the mechanical properties of implant materials.The application of metal ions in bone tissue engineering is full of prospects.Although some metal ions can already be used to treat bone defects,the mechanism of action of many metal ions in the human body is not completely clear,and the application effect is a lack of clinical experiment verification.Further exploration is needed before clinical application.
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BACKGROUND:Hydrogel microparticles,due to their porous and injectable properties,have demonstrated unique advantages in biomedical fields,such as the delivery of cells and bioactive factors/drugs,the construction of tissue repair scaffolds.They have broad application prospects. OBJECTIVE:To review the latest research progress and discuss the key problems and challenges in the research of bone tissue engineering based on hydrogel microparticles. METHODS:The relevant articles in PubMed and CNKI were searched by computer.The English key words were"hydrogels,microparticles,microspheres,microcarriers,bone,bone defect,bone repair,bone healing,bone tissue engineering"while the Chinese key words were"hydrogels,microparticles,microspheres,bone tissue engineering,bone defect,bone repair,bone regeneration".The retrieval period was from 2002 to 2022,and 127 articles were finally included for review. RESULTS AND CONCLUSION:(1)At present,various hydrogel microparticles have been developed for use in bone tissue engineering strategies,for example,hydrogel microparticles carrying cells or bioactive factors/drugs,hydrogel microparticles as biological scaffolds,stimulus-responsive hydrogel microparticles,biomineralized hydrogel microparticles,hydrogel microparticles combined with other biological materials.(2)Bone tissue engineering repair strategies based on hydrogel microparticles mainly regulate bone repair by promoting stem cell recruitment and osteogenic differentiation,regulating the local inflammatory microenvironment and promoting angiogenesis at the site of injury.However,the present studies did not deeply explore the effect of bone tissue engineering based on hydrogel microparticles on the recruitment and differentiation of endogenous stem cells and the regulation of the inflammatory microenvironment by the physical and chemical properties of hydrogel microparticles.The long-term in vivo adverse reactions of hydrogel microparticles have not been explored yet,and it is difficult to mass-produce them,thus future research needs to strengthen the mechanism exploration and technical route,so as to provide a reasonable reference for the development of hydrogel microparticles that can be used for clinical transformation.
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BACKGROUND:In recent years,with the development of biological scaffold materials and bioprinting technology,tissue-engineered bone has become a research hotspot in bone defect repair. OBJECTIVE:To summarize the current treatment methods for bone defects,summarize the biomaterials and bioprinting technology for preparing tissue-engineered bone scaffolds,and explore the application of biomaterials and printing technology in tissue engineering and the current challenges. METHODS:Search terms were"bone defect,tissue engineering,biomaterials,3D printing technology,4D printing technology,bioprinting,biological scaffold,bone repair"in Chinese and English.Relevant documents published from January 1,2009 to December 1,2022 were retrieved on CNKI,PubMed and Web of Science databases.After being screened by the first author,high-quality references were added.A total of 93 articles were included for review. RESULTS AND CONCLUSION:The main treatment methods for bone defects include bone transplantation,membrane-guided regeneration,gene therapy,bone tissue engineering,etc.The best treatment method is still uncertain.Bone tissue engineering technology is a new technology for the treatment of bone defects.It has become the focus of current research by constructing three-dimensional structures that can promote the proliferation and differentiation of osteoblasts and enhance the ability of bone formation.Biological scaffold materials are diverse,with their characteristics,advantages and disadvantages.A single biological material cannot meet the demand for tissue-engineered bone for the scaffold.Usually,multiple materials are combined to complement each other,which is to meet the demand for mechanical properties while taking into account the biological properties of the scaffold.Bioprinting technology can adjust the pore of the scaffold,build a complex spatial structure,and is more conducive to cell adhesion,proliferation and differentiation.The emerging 4D printing technology introduces"time"as the fourth dimension to make the prepared scaffold dynamic.With the synchronous development of smart materials,4D printing technology provides the possibility of efficient repair of bone defects in the future.
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BACKGROUND:Near infrared responsive hydrogels,have a variety of excellent properties such as high spatial and temporal precision,remote tunability,and safety and non-invasiveness,providing a new direction of exploration for the development of tissue engineering. OBJECTIVE:To summarize the application progress of near infrared responsive hydrogels in the field of tissue engineering in recent years. METHODS:The literature search was performed on PubMed and CNKI databases.The keywords were"near infrared responsive hydrogels,tissue engineering,bone defect,bone repair,bone regeneration,wound healing,wound dressing,angiogenesis"in Chinese and English.The search time limit was from May 2006 to October 2022 and extended for some classical literature.The abstracts and contents of the retrieved literature were analyzed,and the relevant literature was obtained according to inclusion and exclusion criteria.Finally,97 articles were included for review. RESULTS AND CONCLUSION:(1)Near infrared responsive materials are involved in tissue repair by controlling infection and reducing inflammation,promoting angiogenesis,osteoblast differentiation and new bone formation.(2)Near infrared responsive hydrogel can be prepared by constructing a thermosensitive hydrogel with a photothermal effect or by using a photochemical reaction.(3)Near infrared responsive hydrogels as wound dressings perform various functions such as rapid hemostasis,tissue adhesion through polymerization of polymer monomers,antibacterial and anti-inflammatory effects,and promotion of angiopoiesis and epithelial regeneration through the local photothermal effect of photothermal nanomaterials during soft tissue healing and regeneration.(4)Near infrared responsive hydrogels function during bone reconstruction and repair by promoting osteogenic differentiation of mesenchymal stem cells,stimulating the expression of heat shock proteins,and increasing angiogenesis.(5)Near infrared responsive hydrogels present a combination of multiple therapeutic strategies with significant synergistic therapeutic functions and are also being progressively developed for application in other tissue reconstruction and disease treatment scenarios.
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BACKGROUND:Bioactive glass bone repair material has bone-bonding ability,bone induction ability and bone conduction characteristics.However,the performance of bioactive glass does not meet the requirements of clinical application,and the addition of boron is expected to improve the performance of bioactive glass. OBJECTIVE:To study the effect of different contents of B2O3 replacing SiO2 on the mechanical properties and bioactivity of bioactive glass. METHODS:Based on bioactive glass containing phosphorus nitrogen and oxygen(composition:SiO2-CaO-ZnO-Na2O-Si3N4-P2O5),B2O3 was used to partially replace the SiO2.The basic glass containing B2O3 with a mass fraction of 0%(group A),5%(group B),10%(group C),and 15%(group D)was fired using the high-temperature melting method(the total mass fraction of SiO2 and B2O3 in the basic broken glass was 41%).Porous bioactive glass scaffolds were fabricated by the organic foam impregnation method.Uniaxial compression and three-point bending method of universal mechanical testing machine were used to test mechanical properties.Four groups of scaffolds were immersed in simulated body fluids to detect the degradation performance of scaffolds.Scanning electron microscopy was used to observe the morphological changes of scaffolds before and after soaking.X-ray diffraction was used to analyze the phase composition of scaffolds before and after soaking. RESULTS AND CONCLUSION:(1)With the increase of the mass fraction of B2O3,the compressive strength and bending strength of the porous bioactive glass scaffold increased,and there was a significant difference between the compressive strength and bending strength of the four groups(P≤0.05).(2)After soaking in simulated body fluids,the porous bioactive glass scaffolds degraded gradually with the extension of time.At the same soaking time point,the degradation rate of the scaffolds was accelerated with the increase of the mass fraction of B2O3,and the compressive strength and bending strength of the scaffolds in the four groups were significantly different(P≤0.05).(3)Scanning electron microscopy after soaking in simulated body fluids showed that a large number of granular materials were deposited on the surface of group A and group B after soaking for 1 day.After 3 days,the granular materials on the surface fused with each other to form film-like deposits.After 7 days,the films on the surface fused with each other to form pieces,basically covering the entire surface of the specimen.After soaking for 1 day,film-like material deposition was formed on the surface of group C,and after 3 days,the films on the surface were fused into pieces,basically covering the whole surface of the specimen.After soaking for 1 day in group D,flake material covering the whole surface of the specimen could be seen.(4)X-ray diffraction analysis after 1 day of immersion in simulated body fluids showed that the deposits on the surface of the four groups of scaffolds were crystallized hydroxyapatite.(5)B2O3 replacement of SiO2 can enhance the mechanical properties,degradation properties and in vitro mineralization activity of porous bioactive glass scaffolds.
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BACKGROUND:At present,nanocomposite gelatin methacryloyl hydrogels have been extensively studied in bone tissue engineering. OBJECTIVE:To review the latest research progress of nanocomposite gelatin methacryloyl hydrogels,and introduce the application of nanocomposite gelatin methacryloyl hydrogels in different bone defect environments. METHODS:The computer retrieval was conducted for relevant literature published in CNKI,WanFang,PubMed,and Web of Science databases from 2016 to 2023.The Chinese and English search terms were"gelatin,methacryl*,nano*,bone,bone tissue engineering,bone regeneration,osteogenesis". RESULTS AND CONCLUSION:(1)Up to now,inorganic nanomaterials,organic nanomaterials and organic-inorganic hybrid nanomaterials are the main nanomaterials used as fillers for gelatin methacryloyl.(2)Inorganic nanomaterials enhance the mechanical strength of gelatin methacryloyl,improve its thixotropic properties and degradation rate,and realize the antibacterial,osteogenic,immunoregulatory,angiogenic and other functions of gelatin methacryloyl hydrogel through its surface charge regulation,drug/factor loading,metal ion self-degradation release,etc.(3)Organic nanomaterial and organic-inorganic hybrid nanomaterial composite gelatin methacryloyl hydrogel are two emerging materials.At present,there are relatively few studies,but from the published research,compared with inorganic nanomaterial gelatin methacryloyl hydrogel,organic nanomaterial gelatin methacryloyl hydrogel has better biocompatibility and drug-loading performance.The interaction between nano phase and organic polymer phase is stronger,and the dispersion of nano particles is better.(4)Organic-inorganic hybrid nanomaterial composite gelatin methacryloyl combines the advantages of the previous two,and has better controllability of metal ion release,which proves great research potential.(5)Nanomaterials can enhance the antibacterial,immune regulation,osteogenesis and other biological properties of gelatin methacryloyl,so as to promote bone regeneration in the complex bone defect microenvironment,such as infected bone defect,diabetes,osteosarcoma resection and so on.However,the relevant research of nanocomposite gelatin methacryloyl hydrogel in bone repair is still limited to animal experiments.Further safety testing and clinical studies are still needed.
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BACKGROUND:Hydroxyapatite is the main inorganic component of bone tissue.The polymer has the structure and function of a biomimetic extracellular matrix.The composites of hydroxyapatite and polymer have been widely studied. OBJECTIVE:To summarize the research status of hydroxyapatite composite polymer materials for bone tissue repair. METHODS:The articles collected in PubMed,Web of Science,CNKI and WanFang databases were searched from January 2010 to April 2023.The Chinese and English search terms were"hydroxyapatite,polymer,composites,degradability,bone defect,bone repair".Finally,75 articles were included for review. RESULTS AND CONCLUSION:Polymers often used in composite with hydroxyapatite for bone tissue repair include natural polymers(collagen,chitosan,alginate,serine protein,cellulose,hyaluronic acid,and polyhydroxybutyrate)and synthetic polymers[polylactic acid,polylactic acid-hydroxyacetic acid copolymer,poly(has-lactide),poly(amino acid)and poly(vinyl alcohol)].The mechanical properties and osteoinductivity of hydroxyapatite/polymer composites were improved compared with pure hydroxyapatite.Hydroxyapatite composite with polymers can be made into porous scaffolds,hydrogels,and coatings for bone repair.Hydroxyapatite/polymer composites can accelerate bone reconstruction with a slow release of loaded drugs and cytokines due to their bionic extracellular matrix structure and function.Based on the diversity of causes of bone defects and the fact that bone repair is a complex continuous process involving multiple biological factors and proteins,repair materials with mechanical properties matching bone tissue,degradation processes synchronized with bone repair,and efficient osteogenesis and vascularization need to be further investigated.
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BACKGROUND:The sclerotic zone in the femoral head is an important imaging feature in the progression of steroid-induced femoral head necrosis,which is associated with disease prognosis.Peroxisome proliferator-activated receptor γ coactivator 1α(PGC-1α)has been shown to possess biological activities such as osteogenesis,angiogenesis and anti-mitochondrial apoptosis,which may be closely related to bone repair of steroid-induced femoral head necrosis. OBJECTIVE:To screen for the differential proteins in the sclerotic zone of steroid-induced osteonecrosis of the femoral head versus the normal zone,to screen for hub proteins in the sclerotic zone,and to verify the differential expression of hub proteins in the femoral head specimens following steroid-induced femoral head necrosis,and to to explore the repair pattern of the sclerotic zone following steroid-induced femoral head necrosis. METHODS:Femoral head samples were collected from patients with steroid-induced osteonecrosis of the femoral head receiving total hip arthroplasty.The differentially expressed genes in the sclerotic zone and the normal zone were screened by Tandem Mass Tags and analyzed by GO and KEGG signaling pathways to construct a protein-protein interaction network and screen hub genes.In addition,the expression of hub genes in the sclerotic zone was verified by immunohistochemistry and western blot. RESULTS AND CONCLUSION:Quantitative protein profiling by Tandem Mass Tags revealed that 609 proteins were significantly differentially expressed(Log2FC＞1.20,Log2FC＜0.84 and P＜0.05)in the sclerotic zone of the femoral head compared with the normal zone,of which 290 proteins were upregulated and 319 proteins were downregulated.The GO and KEGG pathway enrichment analyses revealed that among the top 10 enriched pathways,Wnt signaling pathway and life-cycle regulatory pathway were closely related to bone repair;in the life-cycle regulatory pathway,PGC-1α was one of the important proteins.In addition,western blot results verified the low expression of PGC-1α and NRF1 in the sclerotic zone and high expression of Cleaved Caspase-3 in the sclerotic zone compared with the normal zone of steroid-induced femoral head necrosis specimens.Light microscopic immunohistochemical results showed the distribution of PGC-1α,NRF1 and Cleaved Caspase-3 positive expression in the sclerotic and normal zones in the femoral head tissue specimens,indicating the presence of their expression in bone trabeculae,osteoblasts and bone marrow.In contrast,the brown area of the sclerotic zone of femoral head necrosis stained darker and showed more obvious expression of Cleaved Caspase-3.To conclude,in the sclerotic zone of steroid-induced femoral head necrosis,biological behaviors including activation of osteogenesis-related pathways such as Wnt and oxidative apoptosis characterized by low expression of PGC-1 are observed.Low expression of PGC-1α in the sclerotic zone of steroid-induced femoral head necrosis may be associated with the activation of oxidative apoptosis.
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BACKGROUND:Bone has bioelectric effects.However,bone defects can lead to loss of endogenous bioelectricity in bone.The implantation of bone tissue engineering scaffolds with bioelectric effect into bone defects will replenish the missing electrical signals and accelerate the repair of bone defects. OBJECTIVE:To introduce the bioelectric effect of bone tissue and expound the repair effect of electrical stimulation on bone defects,summarize the research progress of bioelectric effect applied to bone tissue engineering,in order to provide new ideas for the research of bone tissue engineering. METHODS:Relevant articles were searched on CNKI,WanFang,PubMed,Web of Science and ScienceDirect databases,using"bioelectrical effect,bioelectrical materials,electrical stimulation,bone tissue engineering,bone scaffold,bone defect,bone repair,osteogenesis"as the English and Chinese search terms.Finally,87 articles were included for analysis. RESULTS AND CONCLUSION:(1)Bioelectrical effect combined with ex vivo electrical stimulation to design bone tissue engineering scaffolds is an ideal and feasible approach,and the main materials involved include metallic materials,graphene materials,natural bio-derived materials,and synthetic biomaterial.At present,the most widely used conductive material is graphene material,which benefits from its super conductivity,large specific surface area,good biocompatibility with cells and bones,and excellent mechanical properties.(2)Graphene materials are mainly introduced into the scaffold as modified materials to enhance the conductivity of the overall scaffold,while its large surface area and rich functional groups can promote the loading and release of bioactive substances.(3)However,there are still some major challenges to overcome for bioelectrically effective bone tissue engineering scaffolds:not only electrical conductivity but also the overall performance of the bracket needs to be considered;lack of uniform,standardized preparation of bioelectrically effective bone tissue engineering scaffolds;extracorporeal electrical stimulation intervention systems are not yet mature enough;lack of individualized guidance on stent selection to enable the selection and design of the most appropriate stent for patients with different pathologies.(4)When designing conductive scaffolds,researchers have to deeply consider the comprehensive effects of the scaffolds,such as biocompatibility,mechanical properties,and biodegradability.This combination of properties can be achieved by combining multiple materials.(5)Beyond that,clinical translation should be the ultimate consideration for conductive stent design.On the basis of evaluating the safe current threshold for electrical stimulation to act on the human body and facilitate the repair of bone defects,animal experiments as well as basic experiments are designed and then applied to the clinic to achieve the ultimate goal of applying bioelectrical effect bone tissue engineering scaffolds in the clinic.
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BACKGROUND:Careful regulation of bone immune response during repair of bone scaffold is important for bone regeneration. OBJECTIVE:To review the influence of bone immune response on bone repair and the design of bone tissue engineering scaffold with regulating bone immune function and its application in bone repair. METHODS:Relevant articles published from 1973 to 2023 were retrieved from Science Direct,PubMed,Web of Science,and CNKI databases.English search terms were"osteoimmunology,macrophages,bone repair materials,bone scaffold,bone defects,bone regeneration".Chinese search terms were"bone immunity,macrophages,bone repair material,bone stent,bone defect,bone regeneration".Totally 80 articles of the latest research progress in this field were summarized and analyzed. RESULTS AND CONCLUSION:(1)A detailed review was conducted on the important time points in the origin and development process of bone immunity,and it was explained that macrophages,as important members of the bone immune regulatory system,can be divided into two phenotypes:M1(pro-inflammatory)and M2(anti-inflammatory),and play a key role in different stages of bone regeneration.During the inflammatory phase,M1 type macrophages can activate osteoclasts,initiate tissue repair processes,and participate in the reconstruction of bone microvascular networks.On the other hand,during the bone tissue regeneration process in the later stages of inflammation,sustained high expression of M1 type macrophages can hinder the formation of new bones.During the repair phase,M2 macrophages can secrete osteogenic cytokines,stimulate osteogenic differentiation and mineralization of bone marrow mesenchymal stem cells,and promote bone formation.On the other hand,long-term activation of M2 macrophages can increase the secretion of fibrogenic molecules,leading to excessive formation of scar tissue and delaying the healing process.Therefore,regulating macrophages to undergo phenotype transformation at appropriate stages and constructing an immune microenvironment beneficial for osteogenesis has great significance for bone regeneration.(2)In the process of designing bone scaffolds with bone immune regulation characteristics,the physical and chemical properties such as scaffold roughness,pore structure,stiffness,hydrophilicity,surface charge,and surface functional groups can be changed to affect non-specific protein and cell adhesion,thereby affecting the interaction between bone scaffolds and the immune system.By designing surface functional coatings of bioactive substances such as hydroxyapatite,bioactive glass,metal ions,extracellular matrix,drugs,cytokines,and exosomes,the immune microenvironment can be actively regulated by releasing bioactive substances after implantation into the body,affecting macrophage polarization and crosstalk between macrophages and bone cells,and promoting more M2 polarization of macrophages,so as to build a bone immune microenvironment that is conducive to bone regeneration.(3)Based on the research and development of bone tissue engineering scaffolds,in addition to focusing on the direct regulatory factors of stem cell osteogenic differentiation,this article also proposes that attention should be paid to the management of the immune microenvironment of stem cell differentiation.By regulating the appropriate bone immune microenvironment,more stem cell osteogenic differentiation can be induced;the osteogenic efficiency of the scaffold can be enhanced,and the concept of"bone immune regulatory characteristics"can be condensed;deeply elucidated the multi-directional regulatory role of the bone immune microenvironment and introduced the existing strategies for changing the physicochemical properties and surface functional coating of scaffolds to endow them with bone immune regulatory potential,providing new ideas for guiding the development of a new generation of bone tissue engineering scaffolds with bone immune regulatory characteristics.However,the bone immune microenvironment is a dynamic equilibrium state,and most of the existing regulatory strategies do not consider the dynamic matching of regulation.Therefore,the research and development of intelligent bone immune regulatory scaffolds with efficient and targeted regulation of the immune microenvironment will be a key focus of attention for scholars in future.
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BACKGROUND:In vitro lymphocyte proliferation test is often used to detect the potential immunogenicity of medical devices,but no detailed extraction conditions and dose are given in the relevant standards. OBJECTIVE:To investigate the effects of different extraction conditions of the test product and different doses of the extract on in vitro human lymphocyte proliferation,and to consider the factors that need to be considered when selecting test conditions for in vitro lymphocyte proliferation test. METHODS:In the experiment,the homogenous bone repair material and heparin-modified intraocular lens were divided into the following 12 groups:(1)Experimental group 1:24-hour complete medium(RPMI modified medium containing 10%fetal bovine serum)extract of 200 μL + lymphocyte suspension of 50 μL;(2)negative control group 1:24-hour complete medium 200 μL + lymphocyte suspension 50 μL;(3)experimental group 2:24-hour complete medium extract 100 μL + lymphocyte suspension 100 μL;(4)negative control group 2:24-hour complete medium 100 μL + lymphocyte suspension 100 μL;(5)experimental group 3:72-hour RPMI modified medium extract(addition of 10%fetal bovine serum before experiment)200 μL + lymphocyte suspension 50 μL;(6)negative control group 3:72-hour RPMI modified medium(addition of 10%fetal bovine serum before experiment)200 μL + lymphocyte suspension 50 μL;(7)experimental group 4:72-hour RPMI modified medium extract(addition of 10%fetal bovine serum before experiment)100 μL + lymphocyte suspension 100 μL;(8)negative control group 4:72-hour RPMI modified medium(addition of 10%fetal bovine serum before experiment)100 μL + lymphocyte suspension 100 μL;(9)positive control group 1:complete medium containing 10 μg/mL plant hemagglutinin-M 200 μL + lymphocyte suspension 50 μL;(10)positive control group 2:complete medium containing 10 μg/mL plant hemagglutinin-M 100 μL + lymphocyte suspension 100 μL;(11)blank control group 1:250 μL complete medium;(12)control group 2:200 μL complete medium.After 3 days of culture,the proliferation of lymphocytes was detected by CCK-8 assay. RESULTS AND CONCLUSION:(1)Under different test conditions,the extracts of the allogeneic bone repair material could enhance the activity of human lymphocytes.Under the condition of 72-hour leaching in RPMI modified medium and the volume ratio of leaching solution and lymphocyte suspension was 4:1,the most significant effect was observed.Heparin-modified intraocular lens extract also had obvious inhibitory effect on lymphocyte activity under this condition;its inhibitory effect on lymphocyte activity may be related to the heparin in the extract.However,the activity of lymphocytes was slightly enhanced by heparin-modified intraocular lens extract under the experimental conditions of complete medium extraction for 24 hours and the volume ratio of extract to lymphocyte suspension was 4:1.(2)Under different extraction conditions and doses,the results of in vitro lymphocyte proliferation test may be quite different.The selection of test conditions should be combined with the clinical application of the product,and the inherent characteristics of the product should also be considered.
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Objective@#To investigate the osteogenic properties of a methacrylated gelatin (GelMA) / bone marrow mesenchymal stem cells (BMSCs) composite hydrogel applied to the skull defect area of rats and to provide an experimental basis for the development of bone regeneration biomaterials.@*Methods@#This study was approved by the Animal Ethics Committee of Nanjing University. A novel photocurable composite biohydrogel was developed by constructing photoinitiators [lthium phenyl (2,4,6-trimethylbenzoyl) phosphinate, LAP], GelMA, and BMSCs. The surface morphology and elemental composition of the gel were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The compressive strength of the gel was evaluated using an electronic universal testing machine. After in vitro culture for 1, 2, and 5 days, the proliferation of the BMSCs in the hydrogels was assessed using a CCK-8 assay, and their survival and morphology were examined through confocal microscopy. A 5 mm critical bone deficiency model was generated in a rat skull. The group receiving composite hydrogel treatment was referred to as the GelMA/BMSCs group, whereas the untreated group served as the control group. At the 4th and 8th weeks, micro-CT scans were taken to measure the bone defect area and new bone index, while at the 8th week, skull samples from the defect area were subjected to H&E staining, van Gieson staining, and Goldner staining to evaluate the quality of bone regeneration and new bone formation.@*Results@#SEM observed that the solidified GelMA showed a 3D spongy gel network with uniform morphology, the porosity of GelMA was 73.41% and the pore size of GelMA was (28.75 ± 7.13) μm. EDX results showed that C and O were evenly distributed in the network macroporous structure of hydrogel. The hydrogel compression strength was 152 kPa. On the 5th day of GelMA/BMSCs culture, the cellular morphology transitioned from oval to spindle shaped under microscopic observation, accompanied by a significant increase in cell proliferation (159.4%, as determined by the CCK-8 assay). At 4 weeks after surgery, a 3D reconstructed micro-CT image revealed a minimal reduction in bone defect size within the control group and abundant new bone formation in the GelMA/BMSCs group. At 8 weeks after surgery, no significant changes were observed in the control group's bone defect area, with only limited evidence of new bone growth; however, substantial healing of skull defects was evident in the GelMA/BMSCs group. Quantitative analysis at both the 4- and 8-week examinations indicated significant improvements in the new bone volume (BV), new bone volume/total bone volume (BV/TV), bone surface (BS), and bone surface/total bone volume (BS/TV) in the GelMA/BMSCs group compared to those in the control group (P<0.05). Histological staining showed continuous and dense formation of bone tissue within the defects in the GelMA/BMSCs group and only sporadic formation of new bone, primarily consisting of fibrous connective tissue, at the defect edge in the control group.@*Conclusion@#Photocuring hydrogel-based stem cell therapy exhibits favorable biosafety profiles and has potential for clinical application by inducing new bone formation and promoting maturation within rat skull defects.
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SUMMARY: Traumatized bone tissue has the capacity to repair itself so that it eventually regains its almost original form, even in the case of artificially inserted implants. The process that stays at the base of the regeneration is represented by osteogenesis or remote osteogenesis. The major difference between the two types of bone formation is the location of the cement line, which is located on the surface of the implant for contact osteogenesis and on the surface of the bone defect for remote osteogenesis. The aim of the present study was to assess the contact osteogenesis in the case of inserted titanium screws in holes with diameters of 1.8 mm and 1 mm respectively. The obtained results show, in the case of the groove with 1.8 mm that the newly proliferated bone represents 73.85 % of the total area, while in the case of the groove with 1 mm in diameter the value of the newly proliferated bone is 26.15 %. In conclusion, the insertion of titanium screws by self-tapping into the hole smaller than the core of the screw is accompanied by bone proliferation by contact osteogenesis much more modest than in the case of insertion into the hole larger than the core of the screw.
El tejido óseo traumatizado tiene la capacidad de reparar en forma espontánea, de modo que eventualmente recupera su forma casi original, incluso en el caso de implantes insertados artificialmente. El proceso que queda en la base de la regeneración está representado por la osteogénesis u osteogénesis a distancia. La principal diferencia entre los dos tipos de formación ósea es la ubicación de la línea de cemento, que se encuentra en la superficie del implante para la osteogénesis de contacto y en la superficie del defecto óseo para la osteogénesis remota. El objetivo del presente estudio fue evaluar la osteogénesis de contacto en el caso de tornillos de titanio insertados en forámenes con diámetros de 1,8 mm y 1 mm respectivamente. Los resultados obtenidos muestran, en el caso del surco de 1,8 mm que el hueso neoproliferado representa el 73,85 % del área total, mientras que en el caso del surco de 1 mm de diámetro el valor del hueso neoproliferado es del 26,15 %. En conclusión, la inserción de tornillos de titanio por autorroscantes en el foramen menor que el núcleo del tornillo se acompaña de una proliferación ósea por osteogénesis de contacto mucho más modesta que en el caso de la inserción en el foramen mayor que el núcleo del tornillo.
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Animales , Masculino , Conejos , Osteogénesis , Prótesis e Implantes , Titanio/química , Tornillos Óseos , OseointegraciónRESUMEN
ABSTRACT Magnesium (Mg) is essential for the metabolic reactions of the human body and is known for its biocompatibility, its mechanical and physical properties are similar to human bone, which is why it is considered to have high potential in biomedical applications such as temporary and resorbable implants. Through surface modifications, the high tendency to corrosion of Mg could be controlled, such as biodegradable membranes that prevent the passage of chloride ions present in the human organism. To prepare the membrane, solutions of chitosan modified with gelatin and/or glutaraldehyde are used and by means of the electrospray method applied to protect the Mg. To simulate body fluid conditions a Kokubo saline solution (BFK) was prepared. The study focuses on evaluating the corrosion rate of Mg with a coating made of a chitosan electrosprayed membrane, applying electrochemical measurements of electrochemical impedance spectroscopy and linear polarization resistance. The key additive to improve the behavior of the membranes was observed with the use of gelatin, where the membrane with the best results lowing corrosion rates is the Mg CH+GE+GL system, which it was observed with very good physical integrity in the images of morphological analyzes of the surface after 30 days of exposure.
RESUMEN El magnesio (Mg) es esencial para las reacciones metabólicas del cuerpo humano y es conocido por su biocompatibilidad, sus propiedades mecánicas y físicas son similares a las del hueso humano, por lo que se considera que tiene un alto potencial en aplicaciones biomédicas como implantes temporales y reabsorbibles. Mediante modificaciones superficiales se podría controlar la alta tendencia a la corrosión del Mg, como por ejemplo membranas biodegradables que impidan el paso de iones cloruro presentes en el organismo humano. Para preparar la membrana se utilizan soluciones de quitosano modificado con grenetina y/o glutaraldehído y mediante el método de electrorociado se aplican para proteger el Mg. Para simular las condiciones de los fluidos corporales se preparó una solución salina de Kokubo. El estudio se enfoca en evaluar la velocidad de corrosión del Mg con un recubrimiento hecho de una membrana electrorociada con quitosano, aplicando técnicas electroquímicas de espectroscopia de impedancia electroquímica y resistencia de polarización lineal. El aditivo clave para mejorar el comportamiento de las membranas se observó con el uso de gelatina, donde la membrana con mejores resultados bajando los índices de corrosión es el sistema Mg CH+GR+GL, el cual se observó con muy buena integridad física en las imágenes de análisis morfológicos de la superficie después de 30 días de exposición.
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Objective To investigate the potential of ginkgolide B(GB)in mitigating vascular endothelial injury by antagonizing endoplasmic reticulum stress(ERS)and elucidate its underlying molecular mechanism.Methods An injury model of human bone marrow-derived endothelial progenitor cells(EPCs)induced by tunica-mycin(TM)was established.Cell proliferation was assessed using MTS assay,while cell viability was determined through Calcein-AM/EthD-I double staining.Transwell assay was employed to evaluate cell migration ability.DCFH-DA staining was utilized to measure intracellular ROS levels,and NADPH activity was quantified via ELISA.JC-1 and DiOC6 staining were performed for qualitative and quantitative assessment of mitochondrial membrane potential respectively.Qrt-pcr analysis was conducted to determine mRNA expression levels,whereas western blot analysis enabled detection of protein expression levels in the cells.Results GB dose-dependently attenuated tunicamycin-induced ERS-mediated endothelial injury in hEPCs,as evidenced by decreased cell viability,impaired cell migration,and angiogenesis inhibition(P<0.01).Furthermore,GB treatment significantly reduced ROS production and NADPH levels within the cells(P<0.01),while also inhibiting ERS-mediated decline in mitochondrial membrane potential concentration-dependently(P<0.01).Additionally,GB inhibited the expression of ERS-related proteins such as GRP78,ATF4,CHOP etc.,regulated apoptosis-related protein Bcl-xl,Bax cleaved caspase-4 cytochrome c;thereby effectively counteracting endoplasmic reticulum stress-induced cellular damage.Conclusions GB exerts a protective effect on vascular endothelium by antagonizing endoplasmic reticulum stress;this mechanism may be attributed to its ability to reduce intracellular reactive oxygen species levels.It also suppresses the expression of ERS-related proteins(CHOP78 and ATF4),and modulates apoptosis-associated proteins(Bcl-xl,Bax,cleaved caspase-4,and cytochrome c).
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Objective@# To investigate the osteogenic effect of β-tricalcium phosphate (β-TCP) and bone morphogenetic protein-2 (BMP-2) in the repair of the alveolar cleft.@*Methods @# Fifty-nine patients with unilateral alveolar cleft who visited Capital Medical University School of Stomatology from January 2016 to May 2021 were included. They were divided into three groups according to the different bone repair materials: autologous bone, β-TCP and BMP-2 +β-TCP. The preoperative and postoperative CBCT data of the patients were imported into Mimics 21.0 software. The preoperative volume of the bone defect and the new volume of bone formation were calculated by the three-dimensional reconstruction method. The osteogenesis rate was calculated to evaluate the osteogenesis effect@*Results@#The wounds in the three groups healed well after the operation, without implant material discharge, infection, dehiscence, rejection or other symptoms. Twelve months after the operation, CBCT scanning and three⁃dimensional reconstruction images of the three groups of patients showed the formation of new bone bridges in the alveolar ridge fissure area. The image density of the new bone tissue was not significantly different from that of normal bone tissue, and the continuity of the maxilla was re⁃ stored to varying degrees. The bone rate of autogenous bone was 65.00% ± 16.66%, β⁃ TCP group and BMP⁃2+ β⁃ The bone composition rate of TCP was 69.82% ± 17.60%, 71.35% ± 17.51%, respectively, and there was no significant dif⁃ ference compared with the autogenous bone group (P = 0.382, P = 0.244). The β⁃TCP and BMP⁃2+ β⁃TCP groups had no significant differences in bone rate (P = 0.789). @*Conclusion@#β⁃TCP could be used to replace autologous bone for alveolar cleft repair. The addition of BMP⁃2 to β⁃TCP did not significantly improve the osteogenesis rate.
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Gelatin microspheres were discussed as a scaffold material for bone tissue engineering, with the advantages of its porosity, biodegradability, biocompatibility, and biosafety highlighted. This review discusses how bone regeneration is aided by the three fundamental components of bone tissue engineering-seed cells, bioactive substances, and scaffold materials-and how gelatin microspheres can be employed for in vitro seed cell cultivation to ensure efficient expansion. This review also points out that gelatin microspheres are advantageous as drug delivery systems because of their multifunctional nature, which slows drug release and improves overall effectiveness. Although gelatin microspheres are useful for bone tissue creation, the scaffolds that take into account their porous structure and mechanical characteristics might be difficult to be created. This review then discusses typical techniques for creating gelatin microspheres, their recent application in bone tissue engineering, as well as possible future research directions.
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Ingeniería de Tejidos/métodos , Andamios del Tejido/química , Gelatina/química , Microesferas , Huesos , PorosidadRESUMEN
Sodium alginate (SA) is a kind of natural polymer material extracted from kelp, which has excellent biocompatibility, non-toxicity, biodegradability and abundant storage capacity. The formation condition of sodium alginate gel is mild, effectively avoiding the inactivation of active substances. After a variety of preparation methods, sodium alginate microspheres are widely used in the fields of biomaterials and tissue engineering. This paper reviewed the common methods of preparing alginate microspheres, including extrusion, emulsification, electrostatic spraying, spray drying and coaxial airflow, and discussed their applications in biomedical fields such as bone repair, hemostasis and drug delivery.
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Alginatos , Materiales Biocompatibles , Sistemas de Liberación de Medicamentos , Microesferas , Procedimientos de Cirugía PlásticaRESUMEN
Abstract Inducible nitric oxide synthase (iNOS) is one of the enzymes responsible for the synthesis of nitric oxide (NO), which is an important signaling molecule with effects on blood vessels, leukocytes, and bone cells. However, the role of iNOS in alveolar bone healing remains unclear. This study investigated the role of iNOS in alveolar bone healing after tooth extraction in mice. Methodology C57Bl/6 wild type (WT) and iNOS genetically deficient (iNOS-KO) mice were subjected to upper incision tooth extraction, and alveolar bone healing was evaluated by micro-computed tomography (μCT) and histological/histomorphometric, birefringence, and molecular methods. Results The expression of iNOS had very low control conditions, whereas a significant increase is observed in healing sites of WT mice, where iNOS mRNA levels peak at 7d time point, followed by a relative decrease at 14d and 21d. Regarding bone healing, both WT and iNOS-KO groups showed the usual phases characterized by the presence of clots, granulation tissue development along the inflammatory cell infiltration, angiogenesis, proliferation of fibroblasts and extracellular matrix synthesis, bone neoformation, and remodeling. The overall micro-computed tomography and histomorphometric and birefringence analyses showed similar bone healing readouts when WT and iNOS-KO strains are compared. Likewise, Real-Time PCR array analysis shows an overall similar gene expression pattern (including bone formation, bone resorption, and inflammatory and immunological markers) in healing sites of WT and iNOS-KO mice. Moreover, molecular analysis shows that nNOS and eNOS were significantly upregulated in the iNOS-KO group, suggesting that other NOS isoforms could compensate the absence of iNOS. Conclusion The absence of iNOS does not result in a significant modulation of bone healing readouts in iNOS-KO mice. The upregulation of nNOS and eNOS may compensate iNOS absence, explaining the similar bone healing outcome in WT and iNOS-KO strains.
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Objective:To prepare the hydrogel scaffolds with different concentrations of laponite and compare their osteogenic properties.Methods:The scaffolds of gelatin/sodium alginate hydrogel into which laponite was added according to the mass ratios of 0%, 1%, 2%, and 3% were assigned into groups T0, T1, T2, and T3. In each group, the compressive modulus was measured and the leaching solution for 24 h extracted to measure the ion release. Bone marrow mesenchymal stem cells (BMSCs) were cultured in the extract medium from each group and common medium (blank group) ( n=3) in the in vitro experiments to determine the expression of osteogenic genes Runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP) and type I collagen after 7 days of culture. In the in vivo experiments, the scaffolds were implanted into the femoral condyle defects in rats, and a blank group with no scaffolds was set. The bone repair in each group was evaluated by hematoxylin-eosin(HE) staining and immunohistochemical staining. Results:The compressive modulus in group T2 [(139.05±6.43) kPa] was significantly higher than that in groups T0, T1 and T3 [(68.83±3.76) kPa, (101.18±3.68) kPa and (125.40±3.28) kPa] ( P<0.05). The ion contents of lithium, magnesium and silicon released from the 24 h leaching solution in group T2 were (0.031±0.005) μg/mL, (3.047±0.551) μg/mL and (5.243±0.785) μg/mL, insignificantly different from those in group T3 ( P> 0.05) but significantly larger than those in group T1 ( P>0.05). The in vitro experiments showed that the expression levels of Runx2, ALP and type I collagen in group T2 were 1.59±0.11, 2.02±0.08 and 1.06±0.17, significantly higher than those in the other groups ( P<0.05). HE staining showed that the implanted hydrogel was tightly bound to the bone tissue. Immunohistochemical staining showed that the numbers of Runx2 and osteocalcin positive cells in group T2 were significantly higher than those in the other groups. Conclusions:With ideal biocompatibility, hydrogel scaffolds with different concentrations of laponite can slowly release the decomposed ions of lithium, magnesium and silicon to promote the osteogenic differentiation of BMSCs and the repair of bone defects in vivo. A 2% concentration of laponite in the hydrogel scaffolds may result in the best results.