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Anodized titania nanotubes have been considered as an effective coating for bone implants due to their ability to induce osteogenesis, whereas the osteogenic mechanism is not fully understood. Our previous study has revealed the potential role of autophagy in osteogenic regulation of nanotubular surface, whereas how the autophagy is activated remains unknown. In this study, we focused on the cell membrane curvature-sensing protein Bif-1 and its effect on the regulation of autophagy. Both autophagosomes formation and autophagic flux were enhanced on the nanotubular surface, as indicated by LC3-II accumulation and p62 degradation. In the meanwhile, the Bif-1 was significantly upregulated, which contributed to autophagy activation and osteogenic differentiation through Beclin-1/PIK3C3 signaling pathway. In conclusion, these findings have bridged the gap between extracellular physical nanotopography and intracellular autophagy activation, which may provide a deeper insight into the signaling transition from mechanical to biological across the cell membrane.
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Autofagia , Proteína Beclina-1 , Diferenciação Celular , Membrana Celular , Osteogênese , Transdução de Sinais , Propriedades de Superfície , Animais , Membrana Celular/metabolismo , Camundongos , Proteína Beclina-1/metabolismo , Titânio/química , Nanotubos/química , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Humanos , Osteoblastos/citologia , Osteoblastos/metabolismo , Linhagem CelularRESUMO
Currently, biomineralization is widely used as a surface modification approach to obtain ideal material surfaces with complex hierarchical nanostructures, morphologies, unique biological functions, and categorized organizations. The fabrication of biomineralized coating for the surfaces of scaffolds, especially synthetic polymer scaffolds, can alter surface characteristics, provide a favorable microenvironment, release various bioactive substances, regulate the cellular behaviors of osteoblasts, and promote bone regeneration after implantation. However, the biomineralized coating fabricated by immersion in a simulated body fluid has the disadvantages of non-uniformity, instability, and limited capacity to act as an effective reservoir of bioactive ions for bone regeneration. In this study, in order to promote the osteoinductivity of 3D-printed PCL scaffolds, we optimized the surface biomineralization procedure by nano-topographical guidance. Compared with biomineralized coating constructed by the conventional method, the nano-topographically guided biomineralized coating possessed more mineral substances and firmly existed on the surface of scaffolds. Additionally, nano-topographically guided biomineralized coating possessed better protein adsorption and ion release capacities. To this end, the present work also demonstrated that nano-topographically guided biomineralized coating on the surface of 3D-printed PCL scaffolds can regulate the cellular behaviors of USCs, guide the osteogenic differentiation of USCs, and provide a biomimetic microenvironment for bone regeneration.
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We examined the effect of a nanoscale titanium surface topography (D) versus two hybrid micro/nanoscale topographies (B and OS) on adherent mesenchymal stem cells (MSCs) and bone marrow derived macrophages (BMMs) function in cell culture and in vivo. In the in vitro study, compared to OS and B surfaces, D surface induced earlier and greater cell spreading, and earlier and profound mRNA expression of RUNX2, Osterix and BMP2 in MSCs. D surface induced earlier and higher expression of RUNX2 and BMP2 and lower expression of inflammatory genes in implant adherent cells in vivo. Measurement of osteogenesis at implant surfaces showed greater bone-to-implant contact at D versus OS surfaces after 21 days. We explored the cell population on the D and OS implant surfaces 24 h after placement using single-cell RNA sequencing and identified distinct cell clusters including macrophages, neutrophils and B cells. D surface induced lower expression and earlier reduction of inflammatory genes expression in BMMs in vitro. BMMs on D, B and OS surfaces demonstrated a marked increase of BMP2 expression after 1 and 3 days, and this increase was significantly higher on D surface at day 3. Our data implicates a dynamic process that may be influenced by nanotopography at multiple stages of osseointegration including initial immunomodulation, recruitment of MSCs and later osteoblastic differentiation leading to bone matrix production and mineralization. The results suggest that a nanoscale topography (D) favorably modulates adherent macrophage polarization toward anti-inflammatory and regenerative phenotypes and promotes the osteoinductive phenotype of adherent mesenchymal stem cells. STATEMENT OF SIGNIFICANCE: Our manuscript contains original data developed to define effects of a novel nanotopography on the process of osseointegration at the cell and tissue level. Few studies have compared the effects of a nanoscale surface versus the more typical hybrid micro/nano-scale surfaces used today. We have utilized single-cell RNA sequencing for the first time to identify earliest cell populations on implant surfaces in vivo. We provide data indicating that the nanoscale surface acts upon both osteoprogenitor and immune cell (macrophages) to alter the process of bone formation in a surface-specific manner. This work represents new observations regarding osseointegration and immunomodulation.
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Subunidade alfa 1 de Fator de Ligação ao Core , Osseointegração , Diferenciação Celular , Osteogênese , Expressão Gênica , Propriedades de Superfície , Titânio/farmacologiaRESUMO
With the lack of minimally invasive tools for probing neuronal systems across spatiotemporal scales, understanding the working mechanism of the nervous system and limited assessments available are imperative to prevent or treat neurological disorders. In particular, nanoengineered neural interfaces can provide a solution to this technological barrier. This review covers recent surface engineering approaches, including nanoscale surface coatings, and a range of topographies from the microscale to the nanoscale, primarily focusing on neural-interfaced biosystems. Specifically, the immobilization of bioactive molecules to fertilize the neural cell lineage, topographical engineering to induce mechanotransduction in neural cells, and enhanced cell-chip coupling using three-dimensional structured surfaces are highlighted. Advances in neural interface design will help us understand the nervous system, thereby achieving the effective treatments for neurological disorders. STATEMENT OF SIGNIFICANCE: ⢠This review focuses on designing bioactive neural interface with a nanoscale chemical modification and topographical engineering at multiscale perspective. ⢠Versatile nanoscale surface coatings and topographies for neural interface are summarized. ⢠Recent advances in bioactive materials applicable for neural cell culture, electrophysiological sensing, and neural implants are reviewed.
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Mecanotransdução Celular , Doenças do Sistema Nervoso , Humanos , Neurônios , Propriedades de SuperfícieRESUMO
OBJECTIVES: Dental implants are currently becoming a routine treatment decision in dentistry. Synthetic polyetheretherketone (PEEK) polymer is a prevalent component of dental implantology field. The current study aimed to assess the influence of Nd:YAG laser nano-topographical surface engineering combined with ultraviolet light or platelet rich fibrin on the bioactivity and osseointegration of PEEK implants in laboratory and animal testing model. MATERIALS AND METHODS: Computer Aided Design-Computer Aided Manufacturing (CAD CAM) discs of PEEK were used to fabricate PEEK discs (8 mm × 3 mm) N = 36 and implant cylinders (3 mm × 6 mm) N = 72. Specimens were exposed to Nd:YAG laser at wavelength 1064 nm, and surface roughness topography/Ra parameter was recorded in nanometer using atomic force microscopy. Laser modified specimens were divided into three groups: Nd:YAG laser engineered surfaces (control), Nd:YAG laser/UV engineered surfaces and Nd:YAG laser/PRF engineered surfaces (N = 12 discs-N = 24 implants). In vitro bioactivity test was performed, and precipitated apatite minerals were assessed with X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). In vivo histomorphometric analysis was performed in rabbits with BIC% calculation. RESULTS: Ra mean value of PEEK laser engineered surfaces was 125.179 nm. For the studied groups, XRD patterns revealed distinctive peaks of different apatite minerals that were demonstrated by SEM as dispersed surface aggregations. There was a significant increase in the BIC% from control group 56.43 (0.97) to laser/UV surfaces 77.30 (0.78) to laser/PRF 84.80 (1.29) (< 0.0001). CONCLUSIONS: Successful engineered nano-topographical biomimetic PEEK implant could be achieved by Nd:YAG laser technique associated with improving bioactivity. The combination with UV or PRF could be simple and economic methods to gain more significant improvement of PEEK implant surface bioactivity with superior osteointegration.
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Implantes Dentários , Lasers de Estado Sólido , Animais , Coelhos , Propriedades de Superfície , Polietilenoglicóis , Cetonas , Apatitas , Minerais , Microscopia Eletrônica de VarreduraRESUMO
Introduction: Congenital or acquired bone defects in the oral and cranio-maxillofacial (OCMF) regions can seriously affect the normal function and facial appearance of patients, and cause great harm to their physical and mental health. To achieve good bone defect repair results, the prosthesis requires good osteogenic ability, appropriate porosity, and precise three-dimensional shape. Tantalum (Ta) has better mechanical properties, osteogenic ability, and microstructure compared to Ti6Al4V, and has become a potential alternative material for bone repair. The bones in the OCMF region have unique shapes, and 3D printing technology is the preferred method for manufacturing personalized prosthesis with complex shapes and structures. The surface characteristics of materials, such as surface morphology, can affect the biological behavior of cells. Among them, nano-topographic surface modification can endow materials with unique surface properties such as wettability and large surface area, enhancing the adhesion of osteoblasts and thereby enhancing their osteogenic ability. Methods: This study used 3D-printed porous tantalum scaffolds, and constructed nano-topographic surface through hydrothermal treatment. Its osteogenic ability was verified through a series of in vitro and in vivo experiments. Results: The porous tantalum modified by nano-topographic surface can promote the proliferation and osteogenic differentiation of BMSCs, and accelerate the formation of new bone in the Angle of the mandible bone defect of rabbits. Discussion: It can be seen that 3D-printed nano-topographic surface modified porous tantalum has broad application prospects in the repair of OCMF bone defects.
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This work aimed to assess the influence of different structured substrates with hydrophilic and hydrophobic properties on micro and nano topographies developed on titanium alloys over pre-osteoblastic cell behavior. Nano topography influences small dimension levels of cell morphology by inducing filopodia formation in cell membranes, irrespectively to the wettability behavior of the surface. Therefore, micro and nanostructured surfaces of titanium-based samples using different techniques of surface modification processing, such as chemical treatments, micro-arc anodic oxidation (MAO), and MAO combined to laser irradiation were developed. Isotropic and anisotropic texture morphologies, wettability, topological parameters and compositional alterations were measured after the surface treatments. Finally, cell viability, adhesion and morphological responses were assessed to investigate the influence of distinct topologies on osteoblastic cells aiming to encounter the conditions to better promote mineralization events. Our study demonstrated that the hydrophilic behavior improves cell adhesion, amplified when effective surface area increases. Surfaces presenting nano topography have a direct influence on cell morphology and play a key role for filopodia formation.
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Ligas , Titânio , Propriedades de Superfície , Titânio/química , Titânio/farmacologia , Comunicação Celular , MonoaminoxidaseRESUMO
Type H vessel, a vascular subtype in bone, is a critical regulator of osteogenesis, but how material properties affect this organ-specific vessel remains unknown. Here, titania nanotubes were fabricated on bone implant surface to investigate the effects of nano-topography on type H vessels. In vivo, surface nanotubes with 20-100 nm diameters promoted the angiogenesis of type H vessels and bone regeneration in mouse femurs to different extents, with the best effects induced by 70 nm diameter. In vitro, bone-specific endothelial cells (BECs) and artery endothelial cells (AECs) presented significantly different behaviors on the same material. Nanotubes with 20 nm small diameters significantly improved the adhesion, proliferation, type H differentiation of BECs and their paracrine function to regulate pre-osteoblasts (POBs), possibly via binding integrin ß1 on the cell membrane, but these effects weakened when tube diameter increased, which conflicted with the results in vivo. Further study suggested that the better in vivo effects by larger diameters of 70-100 nm might be exerted indirectly through remodeling the regulation from POBs to BECs, highlighting the underappreciated indirect bio-effects of materials via intercellular communication. These suggest that nanoscale material topography makes significant impact on the angiogenesis of type H vessels, directly via binding integrins on the cell membrane of BECs and indirectly via modulating the regulation from osteoblastic cells to BECs, both in a size-dependent manner. Cells of the same type but from different tissues may show different responses to the same material, thus material properties should be tailored to the specific cell population. In research on material-tissue interactions, conclusions from in vitro experiments exposing a single type of cell to material might deviate from the truth in vivo, because materials may indirectly influence the targeted cells through modulating intercellular communication. These provide new insights into material-tissue interactions.
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Comunicação Celular , Células Endoteliais , Camundongos , Animais , Regeneração Óssea , Diferenciação Celular , OsteogêneseRESUMO
It is well established that surface topography can affect cell functions. However, finding a reproducible and reliable method for regulating stem cell behavior is still under investigation. It has been shown that cell imprinted substrates contain micro- and nanoscale structures of the cell membrane that serve as hierarchical substrates, can successfully alter stem cell fate. This study investigated the effect of the overall cell shape by fabricating silicon wafers containing pit structure in the average size of spherical-like chondrocytes using photolithography technique. We also used chondrocyte cell line (C28/I2) with spindle-like shape to produce cell imprinted substrates. The effect of all substrates on the differentiation of adipose-derived mesenchymal stem cells (ADSCs) has been studied. The AFM and scanning electron microscopy images of the prepared substrates demonstrated that the desired shapes were successfully transferred to the substrates. Differentiation of ADSCs was investigated by immunostaining for mature chondrocyte marker, collagen II, and gene expression of collagen II, Sox9, and aggrecan markers. C28/I2 imprinted substrate could effectively enhanced chondrogenic differentiation compared to regular pit patterns on the wafer. It can be concluded that cell imprinted substrates can induce differentiation signals better than engineered lithographic substrates. The nanostructures on the cell-imprinted patterns play a crucial role in harnessing cell fate. Therefore, the patterns must include the nano-topographies to have reliable and reproducible engineered substrates.
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Condrócitos , Células-Tronco Mesenquimais , Diferenciação Celular , Células-Tronco , Colágeno/metabolismo , Condrogênese , Células CultivadasRESUMO
INTRODUCTION: Interproximal enamel reduction is a part of the orthodontic treatment as a method of space generation in addition to other vast indications. Some studies found that different techniques might impose changes to the enamel surface that alter its topography, which in turn might influence its integrity and susceptibility to caries. Polishing, however, after this procedure is thought to be helpful to reduce these adverse effects. AIM: To evaluate the nano-topography of the enamel surfaces after interproximal reduction (IPR) and determine its influence on enamel surface roughness and examine the need for polishing to minimise these influences, when combined with topical fluoride application. METHODS: A total of 60 proximal surfaces of 40 extracted maxillary premolars (10 premolars left unprepared as the control group) were reduced with different stripping instruments (discs, burs and manual strip system). The surface roughness of enamel was analysed with an atomic force microscope to determine the results quantitatively as well as qualitatively on the nanoscopic scale. One of each proximal surface was followed by polishing and fluoride varnish after the reduction. RESULTS: The results showed that surface roughness was increased in all groups without polishing. The greatest mean roughness was recorded for the disc group (212 ±125.7), followed by the bur group (172 ±93.1) and manual strips (153.8±106.7). The difference between the groups, however, was not significant for both mean roughness (P = 0.656) and height (P = 0.737). The parameters were decreased after polishing in all groups but the difference between methods was not significant for both parameters (P = 0.946 and P = 0.849); however, the mean height was reduced to nearly half the reading in the bur and manual strip method. The disc group only showed a statistically significant decrease in surface roughness with polishing (P < 0.05). All other results were not significant. CONCLUSION: All methods of interproximal reduction do not influence enamel surface nanotopography significantly with and without polishing. Polishing resulted in significant reduction of surface roughness only in the disc group.
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Esmalte Dentário , Humanos , Esmalte Dentário/ultraestrutura , Dente Pré-Molar , Propriedades de SuperfícieRESUMO
Tissue engineering is thought to be the ideal therapy for bone defect reconstructive treatment. In this study, we present a method of utilizing micro/nano porous polycarbonate membranes (PCMs) as the extracellular matrix to cultivate the human periodontal ligament cells (hPDLCs) and investigate the osteogenic differentiation of those cells. We also compared the osteogenic enhancing abilities of different pore size PCMs. The pore diameters of the candidate membranes are 200 nm, 800 nm, 1200 nm, and 10 µm respectively, and their physical properties are identified. After seeding and cultivating on the PCMs, hPDLCs can be stimulated to undergo osteogenic differentiation, in which the 200 nm PCM is proved to have the most optimal osteo-induction ability. The results of in vivo experiments provide strong evidence suggesting that the hPDLCs stimulated by 200 nm PCM greatly accelerates the healing of bone reconstruction in mice skull defects, as well as promote the process of ectopic osteogenesis. RNA-sequencing was conducted to determine the differential mRNA expression profile during the osteogenesis process of hPDLCs on PCMs. GO and KEGG enrichment analysis were conducted to study the regulatory mechanisms, in which osteogenic marker expression such as Hippo, TGF-ß, and PI3K-Akt signaling pathways were significantly up-regulated. The up-regulation indicates the promising potential of nano porous PCMs for promoting osteogenesis for bone regeneration applications. Ultimately, signaling pathways that promote osteogenesis warrants further exploration.
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Osteogênese , Fosfatidilinositol 3-Quinases , Humanos , Animais , Camundongos , Osteogênese/genética , Adesão Celular , Células Cultivadas , Diferenciação Celular , Ligamento Periodontal , RNA Mensageiro/genéticaRESUMO
Selective laser melting manufacture of patient specific Ti implants is serving as a promising approach for bone tissue engineering. The success of implantation is governed by effective osseointegration, which depends on the surface properties of implants. To improve the bioactivity and osteogenesis, the universal surface treatment for SLM-Ti implants is to remove the primitive roughness and then reengineer new roughness by various methods. In this study, the micro-sized partially melted Ti particles on the SLM-Ti surface were preserved for assembling mesoporous bioactive glass nanospheres to obtain a unique micro/nano- topography through combination of SLM manufacture and sol-gel processes. The results of simulated body fluid immersion test showed that bioactive ions (Ca, Si) can be continuously and stably released from the MBG nanospheres. The osseointegration properties of SLM-Ti samples, examined using pre-osteoblast cells, showed enhanced adhesion and osteogenic differentiation compared with commercial pure titanium commonly used as orthopedic implants. Overall, the developed approach of construction of the dual micro/nano topography generated on the SLM-Ti native surface could be critical to enhance musculoskeletal implant performance.
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The immune response induced by surface topography crucially determines the implant success. However, how the immune response is mediated by the size of surface topography remains unclear. Hence, various biocompatible Mg-Al layered double hydroxides sheet-array films with different sizes (nano, micro and nano/micro mixture) were constructed on the biomedical titanium, and their osteo-immunomodulation effects on the macrophages were explored. The nano-sheet array structures significantly promoted the polarization of M2 macrophages by activating the PI3K-AKT-mTOR signaling pathway with high gene expressions of integrin ß2 and FAK. While the micro-sheet array structures enhanced osteogenic differentiation of mouse bone marrow mesenchymal stem cells (mBMSCs) via ROCK-YAP/TAZ-mediated mechanotransduction. Moreover, the nano-sheet array structures promoted the osteogenic differentiation of mBMSCs with a high proportion of M2 macrophages through a shared medium. This study gave further information concerning integrin-induced focal adhesions in cells of different sheet array structures and their role in macrophage polarization and osteogenic differentiation of mBMSCs, which might help to design biomaterial surfaces with optimal geometry for a desired immunemodulation.
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Surface characteristics are an important factor for long-term clinical success of dental implants. Alterations of implant surface characteristics accelerate or improve osseointegration by interacting with the physiology of bone healing. Dental implant surfaces have been traditionally modified at the microlevel. Recently, researchers have actively investigated nano-modifications in dental implants. This review explores implant surface modifications that enhance biological response at the interface between a bone and the implant.
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Implantes Dentários , Humanos , Osseointegração/fisiologia , Propriedades de Superfície , TitânioRESUMO
The paper deals with cantilevers made from monocrystalline silicon by processes of microtechnology. The cantilevers are passive structures and have no transducers. The application as a material measure for the inspection of stylus forces is in the center of investigations. A simple method is the measurement of the deflection of the cantilever at the position of load by the force if the stiffness of the cantilever at this position is known. Measurements of force-deflection characteristics are described and discussed in context with the classical theory of elastic bending. The methods of determining the stiffness are discussed together with results. Finally, other methods based on tactile measurements along the cantilever are described and tested. The paper discusses comprehensively the properties of concrete silicon chips with cantilevers to underpin its applicability in industrial metrology. The progress consists of the estimation of the accuracy of the proposed method of stylus force measurement and the extraction of information from a tactile measured profile along the silicon cantilever. Furthermore, improvements are proposed for approaches to an ideal cantilever.
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Micro/nano-topography (MNT) is an important factor affecting cell response. Earlier studies using titania (TiO2) nanotube as a model of MNT found that they mediated the differentiation of BMSCs into osteoblasts, but the mechanisms are not fully understood. Surprisingly, Periostin (Postn), a secreted protein involved in extracellular matrix (ECM) construction and promoting osteogenic differentiation of bone marrow stem cells (BMSCs), was previously observed to significantly up-regulated on TiO2 nanotube. We proposed that Postn may act as a MNT signal transduction role. In this study, we investigated the effect of MNT on Postn, and the influence of Postn on osteogenic differentiation-related genes through focal adhesion and downstream signals. It was found that, titanium (Ti) plates carrying TiO2 nanotubes with diameters of â¼100 nm (TNT-100) significantly up-regulated the expression of Postn compared with flat Ti. Furthermore, Postn activated the downstream focal adhesion kinase (FAK) signal pathway and ß-catenin into the nucleus by interacting with integrin αV. Surprisingly, TNT-100 up-regulated the transcription level of Wnt3a, which was independent of the up-regulation of Postn. This new Postn signaling pathway may provide more insights into the signal transduction mechanism of MNT and development of biomaterials with improved osteogenic properties.
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Células-Tronco Mesenquimais , Osteogênese , Materiais Biocompatíveis/farmacologia , Células da Medula Óssea , Diferenciação Celular , Integrina alfaV/metabolismo , Integrina alfaV/farmacologia , Osteogênese/genética , Titânio/metabolismo , Titânio/farmacologia , beta Catenina/metabolismoRESUMO
The capabilities of osseointegration and anti-inflammatory properties are of equal significance to the bio-inert titanium implant surface. Quercetin has proved its capacities of activating anti-inflammation through macrophage modulation and promoting osteogenic differentiation. Herein, we fabricated quercetin-coating on nano-topographic modificated 3D-printed Ti6Al4V implant surface. Subsequently the biological cells responses in vitro, anti-inflammatory and osseointegration performance in vivo were evaluated. In vitro studies indicated that quercetin-coating can enhance the adhesion and osteogenic differentiation of rBMSCs, while modulating the polarization of macrophages from M1 to M2 phase and improving the anti-inflammatory and vascular gene expression. Moreover, quercetin-loaded implants reduced the level of peri-implant inflammation and ameliorated new bone formation and rapid osseoinegration in vivo. Quercetin-coating might provide a feasible and favorable scheme for endowing 3D-printed titanium alloy implant surface with enhanced the rapid osseointegration and anti-inflammatory properties.
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The titanium implant surface topography optimization for improving osseointegration has been performed for many years, whereas understanding the mechanisms of topography-induced osteogenic differentiation is still insufficient. In this study, the micro/nano-textured topography was created on titanium implant surface by acid etching and anodization. The MC3T3-E1 cells were incubated with different surfaces and the RNA sequencing technique was performed to obtain the transcriptomic information, which suggested the enrichment at "membrane" and "organelle" (GO) as well as "Calcium signal pathway" (KEGG). Consequently, a special attention was paid to the store-operated calcium entry (SOCE) mediated by Orai1 at ER-PM contact site. By fluorescence staining and western blot, it was confirmed that the Orai1 was upregulated on the micro/nano-textured titanium surface, which was correlated to the enhanced osteogenic differentiation induced by topography. Further experiments indicated that the CaMKII/ERK1/2 pathway was involved in. This research is the first time giving a comprehensive transcriptomic information of osteoblasts on micro/nano-textured topography and may provide deeper insight into the interaction between biomaterials and host.
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Osteogênese , Titânio , Materiais Biocompatíveis , Diferenciação Celular/genética , Osteoblastos , Osteogênese/genética , Titânio/farmacologiaRESUMO
Electrotaxis, the directional migration of cells in a constant electric field, is important in regeneration, development, and wound healing. Electrotaxis has a slower response and a smaller dynamic range than guidance by other cues, suggesting that the mechanism of electrotaxis shares both similarities and differences with chemical-gradient-sensing pathways. We examine a mechanism centered on the excitable system consisting of cortical waves of biochemical signals coupled to cytoskeletal reorganization, which has been implicated in random cell motility. We use electro-fused giant Dictyostelium discoideum cells to decouple waves from cell motion and employ nanotopographic surfaces to limit wave dimensions and lifetimes. We demonstrate that wave propagation in these cells is guided by electric fields. The wave area and lifetime gradually increase in the first 10 min after an electric field is turned on, leading to more abundant and wider protrusions in the cell region nearest the cathode. The wave directions display 'U-turn' behavior upon field reversal, and this switch occurs more quickly on nanotopography. Our results suggest that electric fields guide cells by controlling waves of signal transduction and cytoskeletal activity, which underlie cellular protrusions. Whereas surface receptor occupancy triggers both rapid activation and slower polarization of signaling pathways, electric fields appear to act primarily on polarization, explaining why cells respond to electric fields more slowly than to other guidance cues.
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Dictyostelium , Movimento Celular/fisiologia , Dictyostelium/fisiologia , Eletricidade , Transdução de Sinais , CicatrizaçãoRESUMO
The efficacy of an implant is highly depends on its coating characteristics mainly determined by polymer properties and coating technique. Electro-spraying is an inexpensive and versatile coating technique with various advantages for biomedical application. In this study, the efficacy of electro-sprayed (ES) poly lactic acid (PLA)-dexamethasone (DEX) coatings for medical implants was evaluated and compared with spin-coated samples as control. Structural properties of coatings were investigated using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Confocal and scanning electron microscopy (SEM), contact angle measurement and nanoindentation tests were used to study surface properties. Coating degradation rate and drug release profile were studied for 40 days. Cell viability experiments were also performed on human endothelial (HUVEC) and smooth muscle cells (HUASMC) using MTT assay and SEM. XRD and DSC analysis showed electro-spraying significantly reduce PLA and DEX crystallinity. Surface studies showed ES coatings has significantly higher hydrophobicity and roughness with microbead-nanofiber morphology vs. micro-nanoporous structure of spin-coated samples. Initial burst release of DEX was 22% and 10% after 6 h and total release was 71% and 46% after 40 days for ES and spin-coated samples, respectively. HUVEC viability of ES samples was higher than spin-coated ones after 1 and 4 days. However, dexamethasone release profile reduced HUASMC proliferation in ES PLA-DEX samples in comparison to spin-coated after 1 and 3 days. In conclusion, in vitro results showed potential of ES PLA-DEX as a biocompatible and efficient anti-inflammatory coating with suitable drug release profile for future applications such as coronary drug eluting stents.