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Objective:To explore the effects of different polymers on in vitro biomimetic mineralization of small intestinal submucosa(SIS)scaffolds,and to evaluate the physicochemical properties and bio-compatibility of the SIS scaffolds.Methods:The SIS scaffolds prepared by freeze-drying method were im-mersed in simulated body fluid(SBF),mineralized liquid containing polyacrylic acid(PAA)and mine-ralized liquid containing PAA and polyaspartic acid(PASP).After two weeks in the mineralized solu-tion,the liquid was changed every other day.SBF@SIS,PAA@SIS,PAA/PASP@SIS scaffolds were ob-tained.The SIS scaffolds were used as control group to evaluate their physicochemical properties and bio-compatibility.We observed the bulk morphology of the scaffolds in each group,analyzed the microscopic morphology by environment scanning electron microscopy and determined the porosity and pore size.We also analyzed the surface elements by energy dispersive X-ray spectroscopy(EDX),analyzed the struc-ture of functional groups by Flourier transformed infrared spectroscopy(FTIR),detected the water ab-sorption rate by using specific gravity method,and evaluated the compression strength by universal me-chanical testing machine.The pro-cell proliferation effect of each group of scaffolds were evaluated by CCK-8 cell proliferation method.Results:Under scanning electron microscopy,the scaffolds of each group showed a three-dimensional porous structure with suitable pore size and porosity,and crystal was observed in all the mineralized scaffolds of each group,in which the crystal deposition of PAA/PASP@SIS scaffolds was more regular.At the same time,the collagen fibers could be seen to thicken.EDX analysis showed that the characteristic peaks of Ca and P were found in the three groups of mineralized scaffolds,and the highest peaks were found in the PAA/PASP@SIS scaffolds.FTIR analysis proved that all the three groups of mineralized scaffolds were able to combine hydroxyapatite with SIS.All the scaf-folds had good hydrophilicity.The compressive strength of the mineralized scaffold in the three groups was higher than that in the control group,and the best compressive strength was found in PAA/PASP@SIS scaffold.The scaffolds of all the groups could effectively adsorb proteins,and PAA/PASP@SIS group had the best adsorption capacity.In the CCK-8 cell proliferation experiment,the PAA/PASP@SIS scaffold showed the best ability to promote cell proliferation with the largest number of living cells observed.Con-clusion:Compared with other mineralized scaffolds,PAA/PASP@SIS scaffolds prepared by mineralized solution containing both PAA and PASP have better physicochemical properties and biocompatibility and have potential applications in bone tissue engineering.
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The prevalence of periodontal disease in Chinese population is more than 90％.The present treatment techniques can only control the development of the disease,inducement of bone tissue regeneration is a promising strategy and a challenge for the treatment.Exosomes are multivesicle structures derived from endosomes.More and more studies have been conducted on their application in perio-dontal regeneration.This paper reviews the application of exosome in periodontal regeneration in recent years,which is expected to pro-vide new idea for periodontal regeneration therapy.
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BACKGROUND:The repair of maxillofacial bone tissue defects is a hot and difficult point in current research and the selection of seed cells is the key.Jaw bone marrow mesenchymal stem cells are adult mesenchymal stem cells that exist in the jaw bone.They have advantages in the application of maxillofacial tissue regeneration. OBJECTIVE:To summarize the biological characteristics,osteogenic differentiation advantages of jaw bone marrow mesenchymal stem cells,and the effects of drugs,in vivo environment,and microRNAs on the osteogenic differentiation of jaw bone marrow mesenchymal stem cells. METHODS:Computers were used to perform literature retrieval in PubMed and CNKI.Chinese and English search terms were"oral,bone tissue engineering,stem cells".405 articles were retrieved and downloaded.The articles were screened according to the inclusion and exclusion criteria and 70 articles were finally included for literature review. RESULTS AND CONCLUSION:Jaw bone marrow mesenchymal stem cells were excellent seed cells for oral bone tissue engineering,and had good proliferation and osteogenic differentiation potential.Drugs,in vivo environment and microRNAs could regulate the osteogenic differentiation of jaw bone marrow mesenchymal stem cells.However,the research on jaw bone marrow mesenchymal stem cells was still in the initial stage,so more research with strong demonstration is needed to confirm that jaw bone marrow mesenchymal stem cells have more advantages in the application of maxillofacial bone tissue regeneration.
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BACKGROUND:Cartilage defects are one of the major clinical challenges faced by orthopedic surgeons.Tissue engineering is an interdisciplinary approach that combines knowledge of engineering and cell biology to provide new ideas and approaches for the repair of cartilage defects. OBJECTIVE:To prepare a multi-component composite scaffold based on silk fibroin,gelatin,and chitosan to screen for a three-dimensional porous scaffold suitable for cartilage regeneration by evaluating its physicochemical properties and biological performance. METHODS:Four groups of porous scaffolds were prepared by vacuum freeze-drying method using silk fibroin,gelatin and chitosan as the base materials,namely chitosan/gelatin scaffold,silk fibroin/chitosan scaffold,silk fibroin/gelatin scaffold and silk fibroin/chitosan/gelatin scaffold.The suitable cartilage scaffolds were screened by scanning electron microscopy,X-ray diffractometer,porosity,water absorption and swelling rate,biodegradation rate and mechanical property detection.Then cartilage scaffolds were co-cultured with chondrocytes isolated and extracted from patients with osteoarthritis.The feasibility of porous scaffolds for cartilage injury repair was evaluated in vitro by cell adhesion rate assay,cell live-dead staining and cell activity proliferation assay. RESULTS AND CONCLUSION:(1)All four groups of scaffolds had porous structures.The comprehensive physical performance test results showed that the silk fibroin/gelatin/chitosan scaffold was more in line with the requirements of cartilage defect repair.This scaffold had a pore size of(176.00±53.68)μm,the porosity of(80.15±2.57)%,and water absorption and swelling rate of(3 712±358)%.After immersion in PBS containing lysozyme for 28 days in vitro,the biodegradation rate was(46.87±3.25)%,and it had good mechanical properties.(2)Chondrocytes could adhere well on the silk fibroin/gelatin/chitosan scaffold,and the cell adhesion rate increased with time.CCK8 and live/dead cell double staining results showed that silk fibroin/gelatin/chitosan scaffold had good biocompatibility and low cytotoxicity.(3)The results showed that silk fibroin/gelatin/chitosan scaffold had a highly hydrated 3D structure,suitable pore size and porosity,good biodegradability and superior mechanical properties,which can provide a good reticular skeleton and microenvironment for nutrient transport and chondrocyte attachment and proliferation.
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BACKGROUND:Traumatic patellar dislocation with medial patellofemoral ligament tearing at femoral attachment or body is usually performed by medial patellofemoral ligament reconstruction surgery.To promote tendon bone healing after medial patellofemoral ligament reconstruction,the researchers used a variety of biological treatment technologies including growth factors,stem cells and platelet-rich plasma. OBJECTIVE:To investigate the clinical effect of medial patellofemoral ligament reconstruction by leukocyte-and platelet-rich fibrin with autologous hamstring tendon for traumatic patellar dislocation. METHODS:Thirty-seven patients with traumatic patellar dislocation in First Hospital of Qinhuangdao from February 2019 to February 2021 were randomly divided into a trial group(n=18)and a control group(n=19).The trial group received medial patellofemoral ligament reconstruction by leukocyte-and platelet-rich fibrin with an autologous hamstring tendon.The control group received medial patellofemoral ligament reconstruction by a simple autologous hamstring tendon.Patients in the two groups were followed up for 12 months.Knee pain and functional status were evaluated by visual analog scale score,Lysholm score,Kujala patellofemoral joint score and knee range of motion.The patellar tilt angle,patellar congruence angle and patellar lateral shift rate of the patellofemoral joint were measured by MRI and CT films to evaluate the stability and improvement of the patellofemoral joint. RESULTS AND CONCLUSION:(1)The visual analog scale scores of the two groups at 6 and 12 months after operation were lower than those before operation(P<0.05).The Lysholm score and Kujala patellofemoral joint score at 6 and 12 months after operation were higher than those before operation(P<0.05).The Lysholm score and Kujala patellofemoral joint score in the trial group were higher than those in the control group 6 months after operation(P<0.05).There was no significant difference between the two groups in the visual analog scale score,Lysholm score and Kujala patellofemoral joint score 12 months after operation(P>0.05).(2)The patellar tilt angle,patellar congruence angle,patellar lateral shift rate and range of motion of the patellofemoral joint were significantly improved in both groups 12 months after operation(P<0.05).The patellar tilt angle was smaller in the trial group than that in the control group 12 months after operation(P<0.05).Patellar congruence angle,patellar lateral shift rate,range of motion and MRI score were not statistically significant between the two groups 12 months after operation(P>0.05).(3)These results confirm that medial patellofemoral ligament reconstruction by leukocyte-and platelet-rich fibrin with autologous hamstring tendon can treat traumatic dislocation effectively,improve the function of the knee joint,and restore the movement track of the patella.
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BACKGROUND:Medical hydrogels are new functional polymer materials with three-dimensional structural networks and excellent biocompatibility,which have been widely studied in the field of tissue engineering and drug carriers,but the research on the combination of medical hydrogels and Chinese medicine for the treatment of diseases based on tissue engineering is still in the early exploration stage.Therefore,through the analysis of the mechanism of the role of medical hydrogels,the integration of medical hydrogels and Chinese medicine in the research of the joint application of the article,can better provide ideas for scientific researchers,and the joint application of Chinese medicine and medical hydrogels is of great significance. OBJECTIVE:To explore the strategy and significance of Chinese medicine combined with medical hydrogel for disease treatment based on tissue engineering research. METHODS:PubMed and CNKI were used to retrieve articles about the application of Chinese medicine combined with medical hydrogel in tissue engineering from January 2010 to November 2022,with the Chinese and English search terms"hydrogel,traditional Chinese medicine,drug carrier,tissue engineering".After the initial screening of all articles according to the inclusion and exclusion criteria,the 61 articles with high relevance were retained for review. RESULTS AND CONCLUSION:(1)Although the application of Chinese medicine combined with medical hydrogel is involved in intra-articular,intra-tissue organ,soft tissue wounds,tissue engineering,etc.,except for the clinical application of Chinese medicine combined with hydrogel dressing for soft tissue injury,other aspects are still in the experimental stage.(2)The development of Chinese medicine combined with medical hydrogel has great potential and development prospects,but there is a certain difficulty in the manufacture of the gel with high-performance requirements,and it is difficult to master the physical and chemical properties precisely.(3)At present,the comprehensive view of injectable hydrogel with the characteristics of easy to use,its joint use of Chinese medicine can be extended to a wider range,can be used for joint,organ,tissue engineering-related disease treatment.Smart hydrogel has high sensitivity and reversible transformation can also meet the use of the special environment.During the combined use of Chinese medicine,it also needs to understand the mechanism of action of Chinese medicine components.(4)The strategy of combining Chinese medicine with medical hydrogels for disease treatment should start with matching the therapeutic effects of Chinese medicine on organs,tissues and cells combined with appropriate types of medical hydrogels to make up for the shortcomings of traditional Chinese medicine delivery methods and frequent drug delivery.In tissue engineering,hydrogels can be loaded with stem cells after Chinese medicine intervention,or with both Chinese medicine and stem cells for disease treatment.(5)In future research of combined Chinese medicine and medical hydrogel application,we also need to consider:we should ensure that the biological properties of medical hydrogel can be quantified,and grasp the characteristics of hydrogel with different manufacturing processes of different materials to produce the required medical hydrogel that meets the application conditions.In Chinese medicine,we need to comprehensively understand and analyze the therapeutic effects and application mechanisms of known Chinese medicine monomer and Chinese medicine compound extracts,so as to achieve a more perfect combination between Chinese medicine and medical hydrogel under a more clear mechanism.With the continuous improvement of medical science and technology innovation,the medical hydrogel can be innovatively combined with other traditional treatment methods of Chinese medicine,such as acupuncture,massage,cupping and so on,to be used from multiple angles.
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BACKGROUND:Currently,electrospun nanofibers,which are biomimetic materials of natural extracellular matrix and contain a three-dimensional network of interconnected pores,have been successfully used as scaffolds for various tissue regeneration,but are still faced with the challenge of extending the biomaterials into three-dimensional structures to reproduce the physiological,chemical as well as mechanical properties of the tissue microenvironment. OBJECTIVE:To summarize the process and principles of electrostatic spinning and to explore the applications of the resulting electrospun nanofibers in tissue regeneration of skin,blood vessels,nerves,bone,cartilage and tendons/ligaments. METHODS:With"electrospinning,electrospun nanofibers,electrospun nanofiber scaffolds,tissue regeneration"as the Chinese and English search terms,Google Academic Database,PubMed,and CNKI were searched,and finally 88 articles were included for review. RESULTS AND CONCLUSION:(1)The electrospun nanofibers are a natural fibrous extracellular matrix mimetic material and contain a three-dimensional network of interconnected pores that have been successfully used as scaffolds for a variety of tissue regeneration applications.(2)Several papers have described the great potential of electrospun nanofiber scaffolds applied to the regeneration of skin,blood vessels,nerves,bones,cartilage and tendons/ligaments,providing a solid theoretical basis for its final application in clinical disease treatment,or for its transformation into practical products to enter the market.(3)However,the current research results are mostly based on cell experimental research results in vitro,and whether it can be finally applied to human body still needs clinical verification.(4)At present,many kinds of electrospun products for various clinical needs have been commercialized in and outside China,indicating that the research field of electrospun nanofiber scaffolds for soft and hard tissue regeneration has great research value and application potential.
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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:With the right bio-inks,3D printing can be used to create replacements for human tissues and organs that work inside the body.In recent years,3D printing technology has developed rapidly and has great application potential in regenerative medicine. OBJECTIVE:To introduce the types of bio-inks for 3D printing,and review the classification,application,advantages and disadvantages of bio-inks,as well as the future vision. METHODS:With"3D printing,biological ink,tissue engineering,hydrogel,synthetic material,cytoactive factor"as search terms,relevant articles published on PubMed and CNKI databases from 2000 to 2022 were searched by computer and finally 83 articles were included for review. RESULTS AND CONCLUSION:3D bioprinting technology has developed rapidly over the past few decades and has received great attention in various fields,including tissue engineering and biomedicine.Compared with the limitations of traditional biological scaffold manufacturing methods in terms of function and structure,3D printing can better simulate the complex structure of biological tissues and has appropriate mechanical,rheological and biological characteristics.Bio-ink is an essential part of 3D printing.Bioscaffolds produced by printing bio-ink prepared by biological materials have great scientific potential and clinical significance in tissue repair and regenerative medicine.The research of the materials itself is also getting more and more attention from experts.Bio-inks for 3D printing come in a variety of materials,from natural to synthetic,to aggregations of cells that do not require any additional biomaterials,and their usefulness in practical use varies.In the future,more and more bio-inks will be developed for tissue engineering.It is necessary to analyze the printability of bio-inks through sufficient experimental simulation and equipment testing to meet the actual medical needs.
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BACKGROUND:Magnetically responsive hydrogels have great advantages in bone tissue engineering,which is more conducive to the minimally invasive and efficient promotion of osteogenesis. OBJECTIVE:To review the application advances of magnetically responsive hydrogels in bone tissue engineering. METHODS:PubMed,Web of Science,WanFang and CNKI databases were used to search relevant literature.The English search terms were"Magnetic Hydrogels,Magnetic Nanoparticles,Superparamagnetic Nanoparticles,Fe3O4,SPIONs,Magnetic Fields,Bone Regeneration,Bone Repair,Bone Tissue Engineering".The Chinese search terms were"Magnetic Hydrogel,Magnetic Nanoparticles,Superparamagnetic Iron Oxide Nanoparticles,Magnetic Field,Iron Oxide Nanoparticles,Bone Regeneration,Bone Reconstruction,Bone Repair,Bone Tissue Engineering".After preliminary screening of all articles according to the inclusion and exclusion criteria,60 articles were finally retained for review. RESULTS AND CONCLUSION:(1)In recent years,due to the emergence of magnetic nanoparticles,more and more magnetic responsive scaffold materials have been developed.Among them,magnetic responsive hydrogels containing iron oxide nanoparticles and superparamagnetic iron oxide nanoparticles have outstanding mechanical properties and good biocompatibility.It can quickly respond to the external magnetic field and provide the magnetic-mechanical signals needed for seed cells to form bone.(2)Magnetic-responsive hydrogel can be used as a carrier to accurately regulate the release time of growth factors.(3)Under the three-dimensional microenvironment culture platform based on magnetically responsive hydrogel,the magnetic force at the interface between the magnetic response hydrogel and cells can activate cell surface sensitive receptors,enhance cell activity,and promote the integration of new bone and host bone.(4)The injectable magnetically responsive hydrogel can be used in the field of magnetic hyperthermia and biological imaging of bone tumors.(5)At present,magnetically responsive hydrogels are expected to mimic the anisotropic layered structure observed in natural bone tissue.However,most of the studies on magnetically responsive hydrogels focus on in vitro studies,and the mechanism of interaction between magnetically responsive hydrogels and the local microenvironment in vivo is still insufficient.(6)Therefore,based on the successful application of magnetic nanoparticles in magnetic resonance imaging,it is expected to optimize the properties of magnetic nanoparticles in the future to construct magnetic responsive hydrogels with suitable degradation properties,mechanical properties,and vascular functionalization,which can monitor changes in vivo in real time.
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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:Early transient presence of M1 macrophages can play a beneficial role after the implantation of bone tissue engineering materials.Recently,strategies for manipulating M1 macrophages to produce an early moderate inflammatory response have been extensively studied and many research advances have been made in the design of bone tissue engineering materials. OBJECTIVE:To review the role of early transient presence of M1 macrophages in bone tissue engineering and recent research advances in the strategy for activating early transient presence of M1 macrophages in the field of bone tissue engineering. METHODS:Relevant literature included in PubMed,WanFang database,and CNKI Database from January 2012 to October 2022 was searched.Search terms were"M1,macrophage,bone immunoregulation,bone defect,osteogenesis,osteoimmunology,angiogenesis"in English and Chinese.After excluding articles irrelevant to the research purpose and repetitive articles,63 papers were finally included for review. RESULTS AND CONCLUSION:The early transient presence of M1 macrophages play a key role in bone tissue engineering by promoting angiogenesis,facilitating osteogenic differentiation of bone marrow mesenchymal stem cells and promoting an M2 macrophage phenotype.Strategies for inducing and activating early transient presence of M1 macrophages can modulate the local immune microenvironment for bone defect repair in a manner consistent with early natural bone healing,including modulation of the physicochemical properties of bone tissue engineering materials to promote appropriate M1 macrophage-mediated inflammatory responses,sequential delivery of cytokines,microRNAs or bioactive ions to facilitate the M1-to-M2 transition of macrophages,and controlled release of anti-inflammatory substances to achieve the maintenance of early inflammatory responses.
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BACKGROUND:For the replacement treatment of long-segment tracheal defects,although tissue engineering research has made some progress in recent years,it is still not perfect,and one of the biggest difficulties is that the hemodynamic reconstruction of the tracheal replacement cannot be achieved rapidly. OBJECTIVE:To preliminarily explore the potential of polycaprolactone scaffolds modified with exosome-loaded hydrogels to construct a rapidly vascularized tracheal substitute. METHODS:Exosomes were extracted from bone marrow mesenchymal stem cells of SD rats.After preparation of hyaluronic acid methacrylate solution,the exosome solution was mixed with hyaluronic acid methacrylate solution at a volume ratio of 1:1.Hyaluronic acid methacrylate hydrogels loaded with exosomes were prepared under ultraviolet irradiation for 5 minutes.The degradation of exosome-unloaded hydrogels and the controlled release of exosome-loaded hydrogels were detected.Polycaprolactone scaffolds were prepared by 3D printing.The pure hyaluronic acid methacrylate solution and the exosome-loaded hyaluronic acid methacrylate solution were respectively added to the surface of the scaffold.Hydrogel-modified scaffolds and exosome-modified scaffolds were obtained after ultraviolet irradiation.Thirty SD rats were randomly divided into three groups with 10 rats in each group and subcutaneously implanted with simple scaffolds,hydrogel-modified scaffolds and exosome-modified scaffolds,respectively.At 30 days after surgery,the scaffolds and surrounding tissues of each group were removed.Neovascularization was observed by hematoxylin-eosin staining and Masson staining and the expression of CD31 was detected by immunofluorescence. RESULTS AND CONCLUSION:(1)As time went by,the hydrogel degraded gradually,and the exosomes enclosed in the hydrogel were gradually released,which could be sustained for more than 30 days.The exosome release rate was faster than the degradation rate of the hydrogel itself,and nearly 20%of the exosomes were still not released after 30 days of soaking.(2)Under a scanning electron microscope,the surface of the simple polycaprolactone scaffold was rough.After hydrogel modification,a layer of gel was covered between the pores of the scaffold,and the scaffold surface became smooth and dense.(3)After 30 days of subcutaneous embedding,hematoxylin-eosin staining and Masson staining showed that more neovascularization was observed inside the scaffolds of the exosome-modified scaffold group compared with the hydrogel-modified scaffold group.The hydrogels on the scaffolds of the two groups were not completely degraded.Immunofluorescence staining showed that CD31 expression in the exosome-modified scaffold group was higher than that in the hydrogel-modified scaffold group(P<0.000 1).(4)These results indicate that hyaluronic acid methacrylate hydrogels can be used as controlled-release carriers for exosomes.The 3D-printed polycaprolactone scaffold modified by hyaluronic acid methacrylate hydrogel loaded with exosomes has good biocompatibility and has the potential to promote the formation of neovascularization.
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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:Sodium alginate,a natural polysaccharide,has become one of the ideal materials for preparing injectable hydrogels because it is an abundant and cheap resource,and has good biocompatibility and biodegradability.It has been widely used in the production of injectable hydrogels. OBJECTIVE:To review the properties of sodium alginate,the preparation of injectable sodium alginate hydrogel,and its application progress in tissue engineering. METHODS:Web of Science,PubMed,and CNKI were searched by computer.Chinese search terms were"sodium alginate;hydrogel;injectable",and English search terms were"alginate;hydrogel;inject".The time range of searching literature was mainly from June 2017 to June 2022. RESULTS AND CONCLUSION:Alginic acid comes from a wide range of sources,and there are many modifiable groups in its molecular structure,so many injectable hydrogels with excellent properties can be produced by various chemical crosslinking or physical crosslinking methods.Introducing other bioactive molecules or drugs into sodium alginate gel can adjust its properties and broaden its application fields.In addition,injectable sodium alginate hydrogels have great application prospects in biomedicine because of their good biocompatibility,biodegradability and other physical and chemical properties.Sodium alginate hydrogels are evenly mixed with various drugs,cells,factors or other biological molecules in vitro,and can form gels in the human body,which plays a pivotal role in gene carrier,cell scaffold and wound repair.
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BACKGROUND:Owing to excellent angiogenesis activity and their participation in the physiological processes such as angiogenesis in osteogenesis,the researches and applications of a variety of metal ions are getting deeper in the field of bone tissue engineering. OBJECTIVE:To systematically explain the mechanism of angiogenesis of different metal ions such as copper ion(Cu2+),magnesium ion(Mg2+),strontium ion(Sr2+),zinc ion(Zn2+),cobalt ion(Co2+)and their current research situation as well as application in the treatment of diseases in the field of bone tissue engineering. METHODS:The two authors used PubMed and CNKI to search the literature published between 2017 and 2022 with the search terms"copper ion,magnesium ion,strontium ion,zinc ion,cobalt ion,bone,angiogenesis"in Chinese and"copper,cuprum,Cu,magnesium,Mg,strontium,Sr,zinc,Zn,cobalt,Co,metal ion,angiogenesis,bone"in English.After reading titles and abstracts,the articles were initially screened,and irrelevant articles were excluded.Finally,114 articles were included for review. RESULTS AND CONCLUSION:(1)Metal ions can regulate angiogenesis by acting on vascular endothelial growth factors,hypoxia-inducible factors,angiogenesis-related genes,endothelial cells and conducting immune regulation of macrophages.(2)Metal ions such as copper,magnesium,strontium,zinc and cobalt are often used to improve the performance of tissue engineering scaffolds due to their significant angiogenic effect.Among them,hydrogels,bioceramics and synthetic polymer materials are widely used at present,and magnesium and its alloys also have advantages due to their excellent bearing capacity.However,these materials all have some defects.Currently,there is no ideal bone replacement material.(3)Various metal ions show different application potentials in bone replacement materials:Copper has antibacterial,angiogenic and osteogenic properties,and is mainly used for bone defects caused by infection and tumors.Magnesium and zinc have strong biodegradability,so the degradation rate should be controlled.Magnesium is corrosive and is mainly used as an alloy.The angiogenesis mechanism of zinc is less involved.Magnesium and strontium are effective in treating osteoporotic bone defects.(4)The above five metal ions(copper,magnesium,strontium,zinc and cobalt)have a significant role in promoting angiogenesis and then promote osteogenesis through angiogenesis.Some ions,such as copper ions,have a bactericidal effect.These ions can be used as a new strategy for the treatment of bone defects caused by tumors,osteoporosis,infection and trauma,but the current clinical trials and application studies of products are relatively insufficient.
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BACKGROUND:Seed cells are seeded on three-dimensional scaffold materials,and three-dimensional culture in bioreactors is a common in vitro tissue engineering culture method,but the changes in cell proliferation and metabolic patterns in bioengineered blood vessel construction are still unclear. OBJECTIVE:To explore the metabolic changes of cells such as oxygen consumption and their causes during the whole process of biological vascular tissue construction by in vitro bioreactor. METHODS:The self-built vascular bioreactor system was used as the platform;bovine vascular smooth muscle cells were used as the seed cells,and a conventional CO2 incubator provided the external gas environment for the cultivation process.Seed cells were seeded on a tubular porous polyglycolic acid scaffold material for three-dimensional culture,and the whole process included a one-week resting period and a seven-week pulsating tensile stress stimulation loading period.A non-invasive monitoring system was built,and the optical dissolved oxygen patch method was used to monitor the changes of dissolved oxygen in the culture solution in the reactor,and the glucose consumption and lactic acid production were measured by regular sampling.CCK-8 assay was used to determine the proliferation of smooth muscle cells on polyglycolic acid three-dimensional scaffold materials.Nicotinamide adenine dinucleotide oxidation state and reduction state ratio(NAD+/NADH)was utilized to understand cell proliferation and metabolism in the early stage of culture.RT-qPCR and western blot assay were applied to detect the expression of proliferation-related genes(Ki67)and glycolysis-related genes(GLUT-1,LDHA). RESULTS AND CONCLUSION:(1)The dissolved oxygen level in the culture solution was(4.314±0.380)mg/L from the cell injection to the end of the resting period(the first week),and gradually stabilized at(1.960±0.866)mg/L after the tensile stress stimulation(the last seven weeks);the two had significant changes(P<0.05).(2)The ratio of glucose consumption to lactic acid production in the cell culture medium YL/G increased rapidly after the cells were injected,and the highest value was above 1 on the fifth day,and then slow down to 0.5(The mean value of YL/G in the resting period was 0.89 and the mean value in the pressurized period was 0.57,P<0.05).(3)CCK-8 assay results showed that A450 value gradually increased after the cells were injected,and reached the highest value on the fifth day,reaching 3.17,and then slowly decreased.At the same time,it was found that Ki67 mRNA was up-regulated on the third day of culture,and then declined.The expression level of Ki67 protein was higher from the third day to the fifth day.(4)The detection of NAD+/NADH showed that the increase was obvious from the fifth to the seventh day after the injection of cells,and the expression of glycolysis-related genes(GLUT-1 and LDHA)was up-regulated and changed synchronously,and the relative expression was higher in the first five days.(5)The results showed that the tissue-engineered blood vessels were constructed using the vascular bioreactor and the smooth muscle cells in the early stage mainly proliferated and exhibited a metabolic feature of low oxygen consumption.The metabolic characteristics of high oxygen consumption were observed during the pulsatile tensile stress stimulation stage.
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BACKGROUND:In response to the limitations of traditional repair methods for bone defects,stem cells are widely used in the research of regenerative medicine.Chemical factors are the current research hotspots,but recent studies confirm that the application of physical factors to regulate stem cell differentiation at home and abroad has been intensifying,and physical factors combined with biological scaffolds in bone tissue engineering provide a new idea and method for solving the difficult problem of bone defect repair,with good development prospects. OBJECTIVE:To summarize the molecular mechanisms of physical factors such as electromagnetic fields and ultrasound on osteogenic differentiation of stem cells as well as the regulation of signaling pathways and the feasibility of their application in bone tissue engineering. METHODS:A computerized search of the CNKI and PubMed for the last 20 years was conducted.In the title and abstract,we used"stem cell,bone defect,osteogenic differentiation,electromagnetic fields,ultrasound,shock wave,low-level laser therapy,mechanical force,bone tissue engineering"in Chinese and"stem cell,osteoporosis,osteogenic differentiation,electromagnetic fields,ultrasound,bone tissue engineering"in English as search terms.A total of 94 relevant articles were included for review. RESULTS AND CONCLUSION:(1)As a non-invasive,non-contact adjuvant therapy,physical factors have a significant impact on bone tissue engineering,and have a positive effect on regulating osteogenic differentiation of stem cells,promoting cell proliferation and viability in bone engineering scaffolds.(2)In addition to activating signaling pathways and osteogenic gene transcription,physical factors can also improve vascularization,increase the volume,area and thickness of bone formed in the stent,promote osseointegration,and improve the success rate of bone scaffolds in regenerating healthy bone tissue.(3)However,the use of physical factors for bone tissue engineering uses different experimental conditions,such as scaffold type,cell type,and intervention conditions,and cannot be directly compared to determine the best parameter settings.There is also a lack of consistency in the effectiveness of these different interventions in promoting fracture healing in clinical use.Therefore,it is necessary to further determine the optimal parameters of physical factors for bone tissue engineering in the future.(4)In general,as an ideal adjuvant therapy,physical factors have great potential in combining with various biomaterials and applying them in bone tissue engineering.