Mechanism and application in tissue engineering of the active ingredient of Drynariae Rhizoma promoting bone defect repair / 中国药房

Bone defect has always been a major clinical challenge because of its great difficulty and long period of treatment. Drynariae Rhizoma is a commonly used medicine in osteology and traumatology of traditional Chinese medicine， and its active ingredients（mainly flavonoids） facilitate osteoblast differentiation of bone marrow mesenchymal stem cells， osteoclast proliferation， vascular-osteogenic coupling， and inhibit osteoclast activity to promote bone mineralization， and repair and reconstruction of bone defect. As a good substitute for bone regeneration drugs， the active constituents of Drynariae Rhizoma can be loaded on scaffold materials of tissue engineering， which greatly improves the bioavailability of the drug. Meanwhile， the sustained-release microspheres also solve some problems such as sudden drug release from the scaffolds， and the composite scaffolds with active ingredient of Drynariae Rhizoma prepared by them have good ossification activity and osteoinduction， with precise bone repair effects， which meet the diverse performance requirements of bone grafts and have a promising clinical application prospect.

Reconstruction of rat calvarial defects utilizing an ultraviolet-cured hydrogel loaded with bone marrow mesenchymal stem cells / 口腔疾病防治

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.

3D printed Mg-incorporated polycaprolactone scaffolds for repairing rat skull defects / 口腔疾病防治

Objective@#To evaluate the bone repair effect of 3D-printed magnesium (Mg)-loaded polycaprolactone (PCL) scaffolds in a rat skull defect model.@*Methods@#PCL scaffolds mixed with Mg microparticles were prepared by using 3D printing technology, as were pure PCL scaffolds. The surface morphologies of the two scaffolds were observed by scanning electron microscopy (SEM), and the surface elemental composition was analyzed via energy dispersive spectroscopy (EDS). The physical properties of the scaffolds were characterized through contact angle measurements and an electronic universal testing machine. This study has been reviewed and approved by the Ethics Committee. A critical size defect model was established in the skull of 15 Sprague-Dawley (SD) rats, which were divided into the PCL group, PCL-Mg group, and untreated group, with 5 rats in each group. Micro-CT scanning was performed to detect and analyze skull defect healing at 4 and 8 weeks after surgery, and samples from the skull defect area and major organs of the rats were obtained for histological staining at 8 weeks after surgery.@*Results@#The scaffolds had a pore size of (480 ± 25) μm, a fiber diameter of (300 ± 25) μm, and a porosity of approximately 66%. The PCL-Mg scaffolds contained 1.0 At% Mg, indicating successful incorporation of Mg microparticles. The contact angle of the PCL-Mg scaffolds was 68.97° ± 1.39°, indicating improved wettability compared to that of pure PCL scaffolds. Additionally, compared with that of pure PCL scaffolds, the compressive modulus of the PCL-Mg scaffolds was (57.37 ± 8.33) MPa, demonstrating enhanced strength. The PCL-Mg group exhibited the best bone formation behavior in the skull defect area compared with the control group and PCL group at 4 and 8 weeks after surgery. Moreover, quantitative parameters, such as bone volume (BV), bone volume/total volume (BV/TV), bone surface (BS), bone surface/total volume (BS/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N) and bone mineral density (BMD), of skull defects were better than those in the other groups, indicating the best bone regeneration effect. H&E, Goldner, and VG staining revealed more mineralized new bone formation in the PCL-Mg group than in the other groups, and H&E staining of the major organs revealed good biosafety of the material.@*Conclusion@#PCL-Mg scaffolds can promote the repair of bone defects and have clinical potential as a new scaffold material for the repair of maxillofacial bone defects.

Preparation of functional polyhydroxyalkanoate microspheres and their antibacterial activity and osteogenic effect evaluation / 中国修复重建外科杂志

OBJECTIVE@#To construct polyhydroxyalkanoate (PHA) microspheres loaded with bone morphogenetic protein 2 (BMP-2) and human β-defensin 3 (HBD3), and evaluate the antibacterial activity of microspheres and the effect of promoting osteogenic differentiation, aiming to provide a new option of material for bone tissue engineering.@*METHODS@#The soybean lecithin (SL)-BMP-2 and SL-HBD3 were prepared by SL-mediated introduction of growth factors into polyesters technology, and the functional microsphere (f-PMS) containing BMP-2 and HBD3 were prepared by microfluidic technology, while pure microsphere (p-PMS) was prepared by the same method as the control. The morphology of microspheres was observed by scanning electron microscopy and the water absorption was detected; the release curves of BMP-2 and HBD3 in f-PMS were detected by ELISA kit. The antibacterial effect of microspheres in Staphylococcus aureus and Escherichia coli was tested with the LIVE/DEADTM BacLightTM bacterial staining kit; the biocompatibility of microspheres was tested using Transwell and cell counting kit 8 (CCK-8). The effect of microspheres on osteogenic differentiation was determined by collagen type Ⅰ (COL-1) immunofluorescence staining and alkaline phosphatase (ALP) concentration.@*RESULTS@#In this experiment, the f-PMS and p-PMS were successfully constructed. Morphological characteristics showed that p-PMS surface was rough and distributed with micropores of 1-3 μm, while f-PMS surface was smooth and existed white granular material. There was no significant difference in water absorption between the two groups (P>0.05). The release curves of BMP-2 and HBD3 in the f-PMS and p-PMS were basically the same, showing both early sudden release and late slow release. The antibacterial activity of f-PMS was significantly higher than that of p-PMS in the test that against Staphylococcus aureus and Escherichia coli (P<0.05), but there was no significant difference in biocompatibility between the two groups (P>0.05). The results of osteogenic differentiation of human BMSCs showed that the fluorescence intensity of osteogenic specific protein COL-1 of f-PMS was significantly higher than that in p-PMS, and the activity of ALP in f-PMS was also significantly higher than that in p-PMS (P<0.05).@*CONCLUSION@#The p-PHA have good antibacterial activity and biocompatibility, and can effectively promote the osteogenic differentiation of human BMSCs, which is expected to be applied to bone tissue engineering in the future.

Research progress on medical devices of polyhydroxyalkanoate in orthopedics / 中国修复重建外科杂志

OBJECTIVE@#To review the research progress of natural biomaterial polyhydroxyalkanoate (PHA) in orthopedics.@*METHODS@#The literature concerning PHA devices for bone defects, bone repair, and bone neoplasms, respectively, in recent years was extensively consulted. The three aspects of the advantages of PHA in bone repair, the preparation of PHA medical devices for bone repair and their application in orthopedics were discussed.@*RESULTS@#Due to excellent biodegradability, biocompatibility, and potential osteoinduction, PHA is a kind of good bone repair material. In addition to the traditional PHA medical implants, the use of electrostatic spinning and three-dimensional printing can be designed to various functional PHA medical devices, in order to meet the orthopedic clinical demands, including the bone regeneration, minimally invasive bone tissue repair by injection, antibacterial bone repair, auxiliary establishment of three-dimensional bone tumor model, directed osteogenic differentiation of stem cells, etc.@*CONCLUSION@#At present, PHA is a hotspot of biomaterials for translational medicine in orthopedics. Although they have not completely applied in the clinic, the advantages of repair in bone defects have been gradually reflected in tissue engineering, showing an application prospect in orthopedics.

Research progress on biocomposites based on bioactive glass / 生物医学工程学杂志

Bioactive glass (BG) has been widely used in the preparation of artificial bone scaffolds due to its excellent biological properties and non-cytotoxicity, which can promote bone and soft tissue regeneration. However, due to the brittleness, poor mechanical strength, easy agglomeration and uncontrollable structure of glass material, its application in various fields is limited. In this regard, most current researches mainly focus on mixing BG with organic or inorganic materials by freeze-drying method, sol-gel method, etc., to improve its mechanical properties and brittleness, so as to increase its clinical application and expand its application field. This review introduces the combination of BG with natural organic materials, metallic materials and non-metallic materials, and demonstrates the latest technology and future prospects of BG composite materials through the development of scaffolds, injectable fillers, membranes, hydrogels and coatings. The previous studies show that the addition of BG improves the mechanical properties, biological activity and regeneration potential of the composites, and broadens the application of BG in the field of bone tissue engineering. By reviewing the recent BG researches on bone regeneration, the research potential of new materials is demonstrated, in order to provide a reference for future related research.

Progress of research on application of chondroitin sulfate in osteogenic repair materials / 口腔医学

@#Chondroitin sulfate is an important component of extracellular matrix (ECM) in animal and human body. In recent years, chondroitin sulfate has been proven to have potential efficacy in biomedical application and has been widely used in bone regeneration and osteogenesis, especially in craniofacial reconstruction and dental medicine. Research shows that chondroitin sulfate derivatives and chondroitin sulfate composite scaffolds have great potential in promoting osteogenesis and biomineralization. However, due to the variety of chondroitin sulfate and various application forms, study on its mechanism of osteogenic repair is still insufficient. In this paper, biological characteristics, bone regeneration and osteogenesis of chondroitin sulfate, its application in different biomaterial design and future prospect are discussed.

Application of gelatin microspheres in bone tissue engineering / 生物工程学报

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.

Preparation and Performance of Three-Dimensional Silk FibroinScaffolds with Different Matrix Stiffness / 医用生物力学

Objective After hydrogen bonding between collagen ( COL) and silk fibroin ( SF ) at different concentrations, a composite scaffold with adjustable stiffness was prepared by combining with gel system, and its physical and chemical properties were characterized. Methods SF with different qualities was dissolved in sodium alginate (SA) solution, then COL solution at different concentration and calcium carbonate ( CaCO3 ) powder were added. The hydrogels of SC1, SC2, and SC3 groups were obtained by taking out the mixed solution and adding some gluconic acid lactone ( GDL) powder, and different SF scaffolds were obtained after freeze drying. Results The SF scaffolds with adjustable stiffness were successfully prepared. The compression moduli of SC1, SC2, and SC3 groups were (17. 31±2. 73), (24. 12±1. 81), (32. 54±1. 81) kPa, respectively. The innerstructure of the scaffolds was observed. From SC1 group to SC3 group, pores of the scaffolds were smaller and fewer, and hydrophilicity of the materials become better and better. Conclusions Three-dimensional ( 3D) porous scaffolds with different matrix stiffness can be prepared by changing the concentration of SF and COL solution. The concentration of SF and COL is proportional to the compression modulus, water absorption, water retention and swelling rate of SF scaffolds, while inversely proportional to porosity. The findings of this study are expected to provide theoretical guidance for construction of scaffolds with appropriate matrix stiffness for inducing osteogenic differentiation of mesenchymal stem cells

Efeitos do laser de baixa intensidade em osteoblastos cultivados em arcabouços nanofibrosos de ácido polilático / Effects of low-intensity laser on osteoblasts cultured on polylactic acid nanofibrous scaffolds

A engenharia de tecidos ósseos é um ramo importante da medicina regenerativa e envolve o desenvolvimento de arcabouços com composição e arquitetura favoráveis à integração celular, além do estudo de fatores capazes de promover a adesão e proliferação celular, incluindo estímulos químicos e biofísicos. O objetivo do estudo foi avaliar a utilização do laser de baixa intensidade (LBI) como uma ferramenta para promover a bioestimulação in vitro de células osteoblásticas cultivadas em arcabouços nanofibrosos de ácido polilático (PLA). Os arcabouços foram produzidos pela técnica de eletrofiação e caracterizados quanto à molhabilidade, composição pela espectroscopia no infravermelho por transformada de Fourier (FTIR), morfologia da superfície por microscópica eletrônica de varredura (MEV), caracterização termogravimétrica (TGA), calorimetria diferencial exploratória (DSC) e cristalinidade por difração de raios-X (DRX). Os ensaios biológicos foram conduzidos com osteoblastos da linhagem OFCOL II cultivados na superfície dos arcabouços e submetidos ou não (grupo controle) a irradiação com laser diodo InGaAIP na potência de 30 mW, nas doses de 1, 4 e 6 J/cm² e nos comprimentos de onda de 660 nm (grupos V1, V4, V6, respectivo as doses) e 780 nm (grupos I1, I4 e I6, respectivo as doses). Os efeitos do LBI na proliferação dos osteoblastos foram avaliados através do método bioquímico Alamar Blue, nos intervalos de 24, 48 e 72h, enquanto a viabilidade e a morfologia celular foram analisadas no intervalo de 72h, através do ensaio Live/Dead e da microscopia eletrônica de varredura (MEV), respectivamente. Os dados do ensaio bioquímico de Alamar Blue mostraram uma maior proliferação celular nos grupos V6 em todos os intervalos analíticos em comparação ao grupo controle (p<0,05). Outras diferenças entre o grupo controle e irradiados foram encontradas apenas nos intervalos de 48h e 72h para V1, e para o grupo IV6 em 72h. O ensaio Live/Dead revelou um aumento na viabilidade celular nos grupos trados com LBI, sendo significativamente maior no grupo V1 quando comparado ao grupo controle. A análise por MEV mostrou adequada interação dos osteoblastos aos arcabouços, com o corpo celular se espalhando ao longo do eixo da nanofibra e a presença de contatos físicos mais evidentes, através da formação de ligação por meio de filopódios e lamelipódios, nos grupos V1, V6 e I6. Em conjunto, os dados do presente trabalho mostraram que o LBI promove a bioestimulação de osteoblastos cultivados sobre nanofibras de PLA, o que aponta para o seu uso potencial nas técnicas de engenharia tecidual óssea, sobretudo no que se refere ao uso do comprimento de onda de 660 nm, a qual apresentou grupos com mais resultados significativos (AU).

Bone tissue engineering is a relevant branch of regenerative medicine and involves the development of scaffolds with composition and architecture favorable to cell integration, in addition to studying factors capable of promoting cell adhesion and proliferation, including chemical and biophysical stimuli. The study aimed to evaluate the use of low-level laser irradiation (LLLI) to promote in vitro biostimulation of osteoblastic cells cultured on polylactic acid (PLA) nanofibrous scaffolds. The scaffolds were produced by the electrospinning technique and characterized in terms of wettability, composition by Fourier transform infrared spectroscopy (FTIR), surface morphology by scanning electron microscopy (SEM), thermogravimetric characterization (TGA), differential scanning calorimetry (DSC) and crystallinity by Xray diffraction (XRD). The biological assays were conducted with osteoblasts of the OFCOL II lineage cultured on the surface of the scaffolds and submitted or not (control group) to irradiation with InGaAIP diode laser, power of 30 mW, with doses of 1, 4 and 6 J/cm² and wavelengths of 660 nm (groups V1, V4, V6, respectively doses) and 780 nm (groups I1, I4 and I6, respectively doses). The effects of LLLT from the perspective of osteoblasts were evaluated using the biochemical method Alamar Blue assay, at intervals of 24, 48 and 72h, while cell viability and morphology were observed at 72h, using the Live/Dead assay and electron microscopy. scan (SEM), respectively. The Alamar Blue assay data showed more significant cell proliferation in groups in the V6 groups at all analytical intervals compared to the control group (p<0.05). Other differences between the control and irradiated groups were found only at intervals of 48h and 72h for V1, and for group IV6 at 72h. The Live/Dead assay revealed an increase in cell viability in the groups treated with LLLT, being significantly higher in the V1 group when compared to the control group. SEM analysis showed adequate interaction between osteoblasts and scaffolds, with the cell body spreading along the nanofiber axis and the presence of more evident physical contacts, through the formation of bonds through filopodia and lamellipodia, in groups V1, V6 and I6. Together, the data from the present study observed that LLLT promotes the biostimulation of osteoblasts cultured on PLA nanofibers, which pointed to its potential use in bone tissue engineering techniques, especially with regard to the use of the wavelength of 660 nm, which presented groups with more significant results (AU).

3D spheroid cell cultures and their role in bone regeneration: a systematic review / Cultivos de esferoides 3D y su papel en la regeneración ósea: una revisión sistemática

Abstract Recently, the 3D spheroid cell culture application has been extensively used in the treatment of bone defects. A wide variety of methodologies have been used, which has made the comparison of results complex. Therefore, this systematic review has two aims: (i) to perform an analysis focused on the role of 3D spheroid cell culture in bone regeneration strategies; and (ii) address the main challenges in clinical application. A search of the following keywords "3D cell culture", "spheroid", and "bone regeneration" was carried out in the PubMed, Scopus, and ScienceDirect databases and limited to the years 2010-2020. Studies were included if their primary objective was the behavior of cell aggregates to formed spheroids structures by different 3D cell culture techniques focused on the regeneration of bone tissue. To address the risk of bias for in vitro studies, the United States national toxicology program tool was applied, and descriptive statistics of the data were performed, with the SPSS V.22 program. A total of 16 studies were included, which met the established criteria corresponding to in vitro and in vitro/in vivo studies; most of these studies used stem cells for the 3D cell spheroids. The most often methods used for the 3D formation were low adherence surface and rotational methods, moreover, mesenchymal stem cells were the cell line most frequently used because of their regenerative potential in the field of bone tissue engineering. Although the advances in research on the potential use of 3D spheroids in bone regeneration have made great strides, the constant innovation in cell spheroid formation methodologies means that clinical application remains in the future as strategy for 3D tissue bioprinting.

Resumen Recientemente, la aplicación del cultivo 3D de esferoides se ha utilizado ampliamente en el tratamiento de defectos óseos. La variedad de metodologías para lograr los cultivos 3D de esferoides ha hecho compleja la comparación de resultados. Por tanto, esta revisión sistemática tiene dos objetivos: (i) realizar un análisis centrado en el papel de los cultivos 3D de esferoides en las estrategias de regeneración ósea; y (ii) abordar los principales desafíos en la aplicación clínica. Se realizó una búsqueda de las siguientes palabras clave "cultivo celular 3D", "esferoide" y "regeneración ósea" en las bases de datos PubMed, Scopus y ScienceDirect y se limitó a los años 2010-2020. Se incluyeron los estudios si su principal objetivo era el comportamiento de agregados celulares para generar las estructuras esferoidales desarrollados por diferentes técnicas de cultivo celular 3D enfocadas a la regeneración del tejido óseo. Para abordar el riesgo de sesgo de los estudios in vitro, se aplicó la herramienta del programa nacional de toxicología de Estados Unidos y se realizaron estadísticas descriptivas de los datos, con el programa SPSS V.22. Se incluyeron un total de 16 estudios, que cumplieron con los criterios establecidos correspondientes a estudios in vitro e in vitro/in vivo; la mayoría de estos estudios utilizaron células troncales para generar los esferoides celulares 3D. Los métodos más utilizados para la formación de los esferoides 3D fueron la superficie de baja adherencia y los métodos de rotación, asimismo, la línea celular de células troncales mesenquimales fueron las más utilizadas debido a su gran potencial regenerativo en el campo de la ingeniería de tejidos óseos. Aunque los avances en la investigación sobre el uso potencial de los cultivos celulares de esferoides 3D en la regeneración ósea han logrado grandes avances, la constante innovación en las metodologías de la generación de esferoides 3D deja claro que la aplicación clínica de estos permanecerá en el futuro como estrategia en la bioimpresión tisular.

CircularRNA CDR1as promotes osteogenic differentiation and angiogenesis related genes expression in mouse bone marrow mesenchymal stem cells / 口腔疾病防治

Objective@# To investigate the effects of over expression and low expression of antisense transcripts of circular RNA cerebellar degeneration associated protein 1 (CDR1as) in Balb/C mouse bone marrow mesenchymal stem cells (BMSCs) on factors related to osteogenesis and angiogenesis.@*Methods@#BMSCs were cultured and identified in vitro. The lentiviral (LV) vector containing the overexpressed and silenced circRNA CDR1as genes and the control lentivirus were respectively transfected into mouse BMSCs, and stable cell lines were screened. The cells were divided into the circRNACDR1as over expression group and the over expression control group, and the CircRNACDR1as low expression group and the low expression control group. The components were stained with Alizarin Red S and alkaline phosphatase after 14 and 21 days of osteoinduction; qRT-PCR was used to detect the target genes circRNA CDR1as, osteogenic differentiation markers alkaline phosphatase (ALP), runt- related transcription factor 2 (RUNX2), osteocalcin (OCN), osteopontin (OPN), osterix(Osx), collagen I (COL-1), and the mRNA expression levels of vascular endothelial grown factor (VEGF) and angiogenin-1 (Ang-1). @*Results@# The results of alizarin red staining and alkaline phosphatase staining showed that the extracellular matrix calcium precipitation and ALP staining area of the over expression experimental group was greater than its control group, and those of the low expression experimental group was less than its control group. As the number of days of osteogenic induction increased, the calcium precipitation and ALP staining in each group also increased. RT-PCR results showed that the mRNA expression levels of circRNA CDR1as, ALP, RUNX2, OCN, OPN, OSX, COL-1, VEGF and Ang-1 in the over expression experimental group BMSCs were significantly increased (P<0.001). In the low expression experimental group, the mRNA expression levels of circRNA CDR1as, ALP, RUNX2, OCN, OPN, OSX, COL-1, VEGF and Ang-1 in BMSCs were significantly reduced (P<0.001). @*Conclusion@# Over expression of the circRNA CDR1as gene promotes the osteogenic differentiation and angiogenesis of BMSCs. Low expression of the circRNA CDR1as gene inhibits the osteogenic differentiation and angiogenesis of BMSCs.

Effects of hypoxia inducible factor-1α on osteogenic differentiation and angiogenesis related factors of bone marrow mesenchymal stem cells / 口腔疾病防治

Objective@#To investigate the level of hypoxia inducible factor-1α (HIF-1α) on osteoblasts and angiogenesis-associated cytokines in bone marrow mesenchymal stem cells (BMSCs) from SD rats.@*Methods@#BMSCs were isolated and cultured and identified by flow cytometry. Plasmid vectors containing upregulated and downregulated HIF-1α gene and a control vector were constructed. The plasmids were transfected into BMSCs by Lipofectamine®LTX transfection reagent, and the cells were divided into an overexpression experimental group, an overexpression control group, a low expression experimental group and a low expression control group. All components were stained with a lizarin red 3 d and 7 d after osteogenesis induction. The mRNA expression levels of the target gene HIF-1α, osteogenic differentiation-specific markers, including Runt-related transcription factor 2 (Runx2) and angiogenic markers, including platelet-derived growth factor-BB (PDGF-BB) and transforming growth factor-β (TGF-β), were detected by RT-PCR. Western blot was used to detect the protein expression of the target proteins HIF-1α, Runx2, and PDGF-BB.@*Results@# The CD29- and CD45-positivity rates of BMSC surface markers identified by flow cytometry were 98.2% and 4.2%, respectively. RT-PCR results showed that the mRNA expression of HIF-1α, Runx2, TGF-β and PDGF-BB was observably increased (P < 0.001). The mRNA expression levels of HIF-1α, Runx2, TGF-β and PDGF-BB in BMSCs from the low expression experimental group were significantly reduced (P < 0.001). Western blot results showed that the expression levels of HIF-1α, Runx2 and PDGF-BB in BMSCs from the overexpression experimental group were all increased (P < 0.001). The expression levels of HIF-1α, Runx2 and PDGF-BB in BMSCs from the low expression experimental group were reduced (P < 0.001). Alizarin red staining results showed that the area of calcium nodules in the low expression experimental group was smaller than that in low expression control group, the area of red calcium nodules in the over expression experimental group was larger than that in over expression control group, and with the increase of osteogenic induction time, the calcification area of each group also increased.@*Conclusion@# Upregulation and downregulation of HIF-1α can regulate the osteogenic differentiation and the expression of angiogenesis related factors of BMSCs.

Effect of mechanical stimulation on the differentiation of stem cells in periodontal bone tissue engineering / 口腔疾病防治

@#Currently, cell transplantation in combination with scaffold materials are one of the main strategies in periodontal bone tissue engineering. In periodontal bone tissues, the stiffness and spatial structure of tissues such as alveolar bone and cementum differ, and the difference in mechanical properties of scaffolds also has disparate effects on the proliferation and differentiation of stem cells. Accumulating evidence shows that mechanical stimulating factors such as matrix stiffness and scaffold topography modulate biological behaviors of various seeding cells, including adipose-derived stem cells and periodontal ligament stem cells. A hard matrix can promote cytoskeletal stretching of stem cells, leading to nuclear translocation of Yes-associated protein (YAP) and promoting osteogenic differentiation by upregulating alkaline phosphatase (ALP) and osteocalcin (OCN) via the Wnt/β-catenin pathway. The topologic structure of scaffolds can affect cell adhesion and cytoskeletal remodeling, increase the hardness of cells and promote the osteogenic differentiation of stem cells. In this paper, the effects of mechanical stimulation on the differentiation of stem cells in periodontal bone tissue engineering are reviewed.

Therapeutic effects of percutaneous vertebroplasty and kyphoplasty on osteoporotic vertebral compression fracture / 中国组织工程研究

BACKGROUND: Percutaneous vertebral body stenting system (VBS) can alleviate patient's pain, recover the height of vertebral body, and correct local kyphosis, but there is no definite clinical study to show that It has obvious advantages over percutaneous kyphoplasty (PKP). OBJECTIVE: To compare the short-term effect of VBS versus PKP in the treatment of osteoporotic vertebral compression fracture. METHODS: Forty patients with osteoporotic vertebral compression fracture who received VBS or PKP between January 2017 and December 2018 In the First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine were included in this study. They were divided into a VBS group (n=15) and a PKP group (n=25) according to surgery method. According to whether fluoroscopic operation was performed in retroextension position, two subgroups were designated: VBS retroextension group (n=7) and PKP retroextension group (n=14). RESULTS AND CONCLUSION: Compared with the PKP group, the amount of bone cement injected Into the vertebra was greater in the VBS group (P 0.05). Compared with preoperative situations, Visual Analogue Scale score was significantly decreased after surgery In both VBS and PKP groups, and further decreased at the last follow-up (P 0.05). These results suggest that VBS and PKP are effective in the treatment of osteoporotic vertebral compression fractures. VBS can better correct compression kyphosis deformity when more bone cement Is injected. The difference of therapeutic efficacy between two surgical approaches can be reduced with proper surgical position, keeping the surgical segment In the retroextension position.

Three-dimensional printing technology and bone tissue engineering research: Literature metrology and visual analysis of research hotspots / 中国组织工程研究

BACKGROUND: With the continuous development of three-dimensional (3D) printing technology and bone tissue engineering, more and more studies have applied 3D printing technology to bone tissue engineering, but the main research status, hot spots and development trend are not clear enough. OBJECTIVE: To explore the current research status, hotspots and development trends of this field through the literature metrology and visual analysis of research hotspots of 3D printing and bone tissue engineering. METHODS: The CNKI database was searched under the theme of “3D printing and bone tissue engineering research”. Based on the quantitative visual analysis method of CNKI literature, the author made a statistical analysis on the trend of the number of publications, publishing institutions and journals of the application of 3D printing technology in bone tissue engineering. VOSviewer software was used to analyze the author collaboration and keyword co-occurrence network of the literature, and the hot research topic was interpreted based on the literature. RESULTS AND CONCLUSION: (1) A total of 469 effective articles related to 3D printing and bone tissue engineering were retrieved. Since 2014, the research on 3D printing and bone tissue engineering has shown a steady growth trend. Chinese Journal of Tissue Engineering Research and Jilin University are the most published journal and institution in this field, respectively. The authors of the literature form five major groups, but there is very little cooperation between the groups. (2) Keywords co-occurrence network shows that the contents revealed by keywords commonly clustering into four research topics (bone tissue engineering scaffold material, 3D printing technology and its application in orthopedics, 3D printing and joint replacement, and others) and the top 10 keywords (3D printing technology, computer aided technology, bone tissue engineering, tissue engineering, fracture, bone defect, hydroxyapatite, three-dimensional, replacement, titanium alloy) really reflect the present situation and the hotspots of current 3D printing and the bone tissue engineering research, which can provide a reference for researchers in this field when choosing a research direction.

Effects and mechanisms of enamel matrix derivatives on osteogenic differentiation of bone marrow mesenchymal stem cells / 中国组织工程研究

BACKGROUND: Bone marrow mesenchymal stem cells have good potential for directional differentiation, but the effect and mechanism of enamel matrix derivatives on osteogenic differentiation are still unclear. OBJECTIVE: To summarize the latest research progress on osteogenic induction of bone marrow mesenchymal stem cells by enamel matrix derivatives. METHODS: Related literature from 2000 to 2020 was searched in CNKI, Wanfang Data, VIP Database, PubMed databases. The key words are “Emdogain® or enamel matrix derivatives, bone marrow mesenchymal stem cells”. The languages of the literature were set to Chinese and English. When retrieving some classic articles, the publication date could be extended appropriately. Finally, 62 English articles and 5 Chinese articles meeting the inclusion criteria were selected. RESULTS AND CONCLUSION: There are different reports on the osteogenic effect of enamel matrix derivatives on bone marrow mesenchymal stem cells. Enamel matrix derivatives may enhance the osteogenic induction ability of bone marrow mesenchymal stem cells, and may enhance the osteogenic effect by affecting cells or cell membranes, but the relevant mechanism is unclear.

Characteristics and application of bioabsorbable materials in orthopedics / 中国组织工程研究

BACKGROUND: Bioabsorbable materials have shown obvious advantages in clinical application for more than ten years, and have been widely used in many biomedical fields. OBJECTIVE: To review characteristics of bioabsorbable materials and their application in orthopedics. METHODS: The articles published in Wanfang, CNKI, VIP, and PubMed databases were searched by computer. The key words were “bioabsorbable materials, bioabsorbable metal materials, bioabsorbable inorganic materials, polymer materials, biocomposites” in Chinese, and “bioabsorbable/bioabsorbable material, metal material, polymer material, biocomposites” in English. RESULTS AND CONCLUSION: Absorbable metal materials have good mechanical properties. The corrosion mechanism of polymer materials is clear, which can predict the corrosion behavior and corrosion rate in vivo and in vitro, but its load-bearing performance is not as good as that of absorbable metal materials. After certain treatment, bioceramics have good biocompatibility, bone conductivity and osseointegration, but they are brittle and difficult to be formed. Biocomposites have the properties of component materials, and can also obtain new properties that single component materials do not have, so it has a wide application prospect.

Role of mesenchymal stem cells migration in bone injury repair / 口腔疾病防治

@#Mesenchymal stem cells (MSCs) are capable of self-replication and multi-directional differentiation, which are very important for the development and reconstruction of mesenchymal tissue. Bone tissue damage repair involves the participation of various cells and molecules. The recovery of bone mass requires sufficiently many MSCs to migrate to the damaged site to perform the reconstruction function. The local inflammatory response at the injury site can recruit MSCs and promote new bone formation. Simultaneously, niche changes during the migration of MSCs will affect their biological performance and initiate the phase of directed differentiation. This article explores the relevant mechanisms that mediate the migration of MSCs in the process of bone injury repair, including the regulation of immune cells and chemotactic signaling molecules in the inflammatory response in the bone repair stage through signaling pathways such as BMP/Smads. Then, it summarizes the mechanism by which the high matrix stiffness upregulates the expression of the integrin and focal adhesions to promote the MSCs migration and osteogenic differentiation. Simultaneously, the migration ability of MSCs can be regulated through drugs or genetic modification to promote the bone injury repair. The improvement of MSCs migration ability can shorten the time of bone tissue damage repair and improve the bone quality. This article reviews the role of the MSCs migration ability in bone tissue injury repair to provide a reference for the application of MSCs with high migration ability in the fields of stem cell therapy for bone related diseases and bone tissue engineering.

Research progress on the reconstruction of mandibular defects in adolescents / 口腔疾病防治

@#Mandibular defects in adolescents are mostly caused by surgical resection of benign and malignant tumors, trauma and jaw inflammation. The reconstruction of mandibular defects in adolescents is challenging. In addition to solving the problem of jaw reconstruction in adults, some clinical factors, including the influence of surgery on the growth of donor and recipient areas, the long-term effects of reconstruction, and the outcome of bone grafts, must also be considered. At present, the main reconstructive methods include autogenous bone grafts and distraction osteogenesis. Autogenous bone grafts are still the gold standard due to their long-term effects. Favorable growth potential after repair was shown in adolescent cases of mandibular reconstruction with fibula flap. Normal occlusion was restored, and a long-term stable effect was achieved in cases of condylar reconstruction with costal cartilage. The safety and clinical effects of distraction osteogenesis have been confirmed, but the long-term effects of large-scale mandibular defects are still uncertain. In addition, other tissue engineering techniques also have good application prospects for the repair and reconstruction of adolescent mandible defects, but more in-depth basic research and more extensive clinical trials should be performed to verify the efficacy.