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1.
PLoS One ; 15(9): e0238590, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32941456

RESUMO

The aim of this study was to evaluate the effect of silver diamine fluoride and grape seed extract on the microstructure and mechanical properties of carious dentin following exposure to acidic challenge. Ninety-eight molars with occlusal caries were used. In the control group the specimens were kept in distilled water. In the GSE group, the specimens were immersed in 6.5% grape seed extract solution for 30 minutes. In the SDF group, the specimens were immersed in 30% SDF solution for 4 minutes. In the GSE+SDF group, the specimens were immersed in 6.5% grape seed extract solution for 30 minutes and then exposed to 30% SDF solution for 4 minutes. All the groups underwent pH cycling model for 8 days. Microhardness measurements were taken at the baseline before surface treatments and after pH cycling. Elastic modulus was measured, after pH cycling. In the control group, the final hardness was significantly lower than the initial hardness (P = 0.001). In the SDF group, the final hardness was significantly higher than the initial hardness (P < 0.001). There was no significant difference between the initial and final hardness values in the GSE and GSE + SDF groups (p = 0.92, p = 0.07). The H1-H0 in the SDF group was significantly higher than the other groups (P<0.05). Moreover, elastic modulus of the experimental groups except GSE+SDF group was significantly higher than control. The highest mean elastic modulus was detected in the SDF group (P<0.001). The use of SDF and GSE prior to the acid challenge improved mechanical properties. Microstructural investigation, using scanning electron microscope showed dentin structure protection against acid challenges with SDF treatment and collagen matrix stabilization with GSE treatment. However combined use of these agents was not beneficious.


Assuntos
Ácidos/efeitos adversos , Dentina/efeitos dos fármacos , Extrato de Sementes de Uva/farmacologia , Proantocianidinas/farmacologia , Substâncias Protetoras/farmacologia , Compostos de Amônio Quaternário/farmacologia , Compostos de Prata/farmacologia , Fenômenos Biomecânicos/efeitos dos fármacos , Dentina/ultraestrutura , Módulo de Elasticidade/efeitos dos fármacos , Fluoretos Tópicos/farmacologia , Humanos
2.
J Orthop Res ; 38(5): 972-983, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31793028

RESUMO

Advanced glycation end-products (AGEs) have been suggested to contribute to bone fragility in type 2 diabetes (T2D). AGEs can be induced through in vitro sugar incubations but there is limited data on the effect of total fluorescent AGEs on mechanical properties of human cortical bone, which may have altered characteristics in T2D. Thus, to examine the effect of AGEs on bone directly in T2D patients with uncontrolled sugar levels, it is essential to first understand the fundamental mechanisms by studying the effects of controlled in vitro-induced AGEs on cortical bone mechanical behavior. Here, human cortical bone specimens from female cadaveric tibias (ages 57-87) were incubated in an in vitro 0.6 M ribose or vehicle solution (n = 20/group) for 10 days at 37°C, their mechanical properties were assessed by microindentation and fracture toughness tests, and induced AGE levels were quantified through a fluorometric assay. Results indicated that ribose-incubated bone had significantly more AGEs (+81%, p ≤ 0.005), lower elastic modulus assessed by traditional microindentation, and lower fracture toughness compared with vehicle controls. Furthermore, based on pooled data, increased AGEs were significantly correlated with deteriorated mechanical properties. The findings presented here show that the accumulation of AGEs allows for lower stiffness and increased ability to initiate a crack in human cortical bone. Statement of clinical significance: High sugar levels as in T2D results in deteriorated bone quality via AGE accumulation with a consequent weakening in bone's mechanical integrity. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:972-983, 2020.


Assuntos
Osso e Ossos/efeitos dos fármacos , Módulo de Elasticidade/efeitos dos fármacos , Produtos Finais de Glicação Avançada/metabolismo , Ribose/toxicidade , Idoso , Idoso de 80 Anos ou mais , Osso e Ossos/metabolismo , Osso e Ossos/ultraestrutura , Feminino , Humanos , Pessoa de Meia-Idade
3.
Mater Sci Eng C Mater Biol Appl ; 104: 109960, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500051

RESUMO

3D printing-based technologies can fabricate scaffolds offer great precision to control internal architecture and print complicated structures based upon the defect site. However, the materials used in the direct printing are restricted depending on the printing technology used and the indirect one can overcome this limitation. In the present study, indirect 3D printing approach was used to develop bone scaffolds from polylactic acid/ polycaprolactone/ hydroxyapatite (PLA/PCL/HA) composites. Casting of the composite suspensions was done into a dissolvable 3D printed negative mold, in order to achieve simultaneous macro- and micro-porous composites, using freeze drying/particle leaching method. To evaluate morphology, functional groups, and elemental analysis of the scaffolds, scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and energy dispersive spectroscopy (EDS) were respectively used. Scaffolds' porosity was measured with the aid of liquid replacement technique. Also, the mechanical strength of scaffolds was examined by compression test and measuring the compressive modulus Considering the microstructure, porosity and pore size as well as mechanical property, the scaffold composed of PLA/PCL 70/30 w/w and 35% HA was more favorable. The PLA/PCL/HA 70/30-35% scaffold presented a porosity of 77%, an average pore size of 160 µm, and Young's modulus of 1.35 MPa. Cell adhesion, viability and mineral deposits formation for PLA/PCL/HA scaffolds at PLA/PCL ratios of 70/30, 50/50 and 30/70 and the fixed amount of HA (35%) were also studied in vitro by the means of MG63 cells. The cytotoxicity assessment showed that the cells could be viable and proliferate on the scaffolds. The results indicated that composite scaffold with the PLA/PCL weight ratio of70/30 accomplished more favorable properties in terms of biocompatibility, viability, and osteoinduction property.


Assuntos
Materiais Biocompatíveis/química , Osso e Ossos/efeitos dos fármacos , Durapatita/química , Poliésteres/química , Tecidos Suporte/química , Adesão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Módulo de Elasticidade/efeitos dos fármacos , Humanos , Teste de Materiais/métodos , Porosidade , Impressão Tridimensional , Engenharia Tecidual/métodos
4.
Int J Mol Sci ; 20(13)2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31277289

RESUMO

Atomic force microscopy (AFM) combined with fluorescence microscopy has been used to quantify cytomechanical modifications induced by resveratrol (at a fixed concentration of 50 µM) in a breast cancer cell line (MCF-7) upon temporal variation. Cell indentation methodology has been utilized to determine simultaneous variations of Young's modulus, the maximum adhesion force, and tether formation, thereby determining cell motility and adhesiveness. Effects of treatment were measured at several time-points (0-6 h, 24 h, and 48 h); longer exposures resulted in cell death. Our results demonstrated that AFM can be efficiently used as a diagnostic tool to monitor irreversible morpho/nano-mechanical changes in cancer cells during the early steps of drug treatment.


Assuntos
Neoplasias da Mama/fisiopatologia , Adesão Celular/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Módulo de Elasticidade/efeitos dos fármacos , Microscopia de Força Atômica/métodos , Resveratrol/farmacologia , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/tratamento farmacológico , Feminino , Humanos , Células MCF-7 , Fenômenos Mecânicos/efeitos dos fármacos , Resveratrol/uso terapêutico
5.
Biochem Biophys Res Commun ; 516(1): 177-182, 2019 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-31204049

RESUMO

Leukemia is a commonly seen disease caused by abnormal differentiation of hematopoietic stem cells and blasting in bone marrow. Despite drugs are used to treat the disease clinically, the influence of these drugs on leukemia cells' biomechanical properties, which are closely related to complications like leukostasis or infiltration, is still unclear. Due to non-adherent and viscoelastic nature of leukemia cells, accurate measurement of their elastic modulus is still a challenging issue. In this study, we adopted rate-jump method together with optical tweezers indentation to accurately measure elastic modulus of leukemia cells K562 after phorbol 12-myristate 13-acetate (PMA), all-trans retinoic acid (ATRA), Cytoxan (CTX), and Dexamethasone (DEX) treatment, respectively. We found that compared to control sample, K562 cells treated by PMA showed nearly a threefold increase in elastic modulus. Transwell experiment results suggested that the K562 cells treated with PMA have the lowest migration capability. Besides, it was shown that the cytoskeleton protein gene α-tubulin and vimentin have a significant increase in expression after PMA treatment by qPCR. The results indicate that PMA has a significant influence on protein expression, stiffness, and migration ability of the leukemia cell K562, and may also play an important role in the leukostasis in leukemia.


Assuntos
Antineoplásicos/farmacologia , Fenômenos Biomecânicos/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Leucemia/tratamento farmacológico , Ciclofosfamida/farmacologia , Dexametasona/farmacologia , Módulo de Elasticidade/efeitos dos fármacos , Humanos , Células K562 , Leucemia/patologia , Acetato de Tetradecanoilforbol/farmacologia , Tretinoína/farmacologia
6.
Artif Cells Nanomed Biotechnol ; 47(1): 1888-1897, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31072140

RESUMO

Storage lesions in red blood cells (RBCs) hinder efficient circulation and tissue oxygenation. The absence of flow mechanics and gas exchange may contribute to this problem. To test if in vitro compensation of flow mechanics and gas exchange helps RBC recovery, three-dimensional polydimethylsiloxane (PDMS) porous structures were fabricated with a sugar mould, simulating lung alveoli. RBC suspensions were passed through the porous structure cyclically, simulating in vivo blood circulation. Acid-base indices, partial gas pressures, ions, glucose and RBC indices were analyzed. An atomic force microscope was used to investigate local mechanical properties of intact RBCs. RBCs suspensions that passed through the porous structures had a higher pH and oxygen partial pressure, and a lower potassium concentration and carbon dioxide partial pressure. Meantime they had better biochemical properties relative to static samples, namely, they exhibited a more homogenous distribution of Young's Modulus. RBCs that passed through a PDMS porous structure were healthier than static ones, giving hints to prevent RBC storage lesions.


Assuntos
Preservação de Sangue , Dimetilpolisiloxanos/química , Dimetilpolisiloxanos/farmacologia , Eritrócitos/efeitos dos fármacos , Gases/metabolismo , Hemorreologia/efeitos dos fármacos , Nylons/química , Nylons/farmacologia , Animais , Fenômenos Biomecânicos/efeitos dos fármacos , Módulo de Elasticidade/efeitos dos fármacos , Eritrócitos/citologia , Eritrócitos/metabolismo , Glucose/metabolismo , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Masculino , Porosidade , Ratos , Ratos Wistar
7.
Biomater Sci ; 7(6): 2545-2551, 2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-30973560

RESUMO

The blood thinning properties of pentoxifylline have been attributed to its ability to increase the deformability of red blood cells and improve their rheological properties. To interpret and substantiate these observations a novel approach is taken by measuring the stiffness of individual red blood cells from healthy humans before and after subscription to pentoxifylline for nine days. Atomic force microscopy nanoindentation experiments reveal that the elastic modulus of the red blood cells decreased by 30%-40%, after pentoxifylline subscription. This decrease in elastic modulus is related to the ability of pentoxifylline to increase the production of ATP and lower Ca2+ concentrations in red blood cells. The present in vivo experiments provide a deeper understanding of the mode of action of pentoxifylline, and pave the way to using indentation in medicine. A further unique advantage of this study is that it was performed on healthy volunteers, rather than requiring in vitro incubation.


Assuntos
Anticoagulantes/farmacologia , Módulo de Elasticidade/efeitos dos fármacos , Eritrócitos/efeitos dos fármacos , Pentoxifilina/farmacologia , Trifosfato de Adenosina/metabolismo , Animais , Cálcio/metabolismo , Eritrócitos/metabolismo , Humanos , Ratos
8.
PLoS One ; 14(4): e0215595, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31002728

RESUMO

Biomechanical research on tendon tissue evaluating new treatment strategies to frequently occurring clinical problems regarding tendon degeneration or trauma is of expanding scientific interest. In this context, storing tendon tissue deep-frozen is common practice to collect tissue and analyze it under equal conditions. The commonly used freezing medium, phosphate buffered saline, is known to damage cells and extracellular matrix in frozen state. Dimethyl sulfoxide, however, which is used for deep-frozen storage of cells in cell culture preserves cell vitality and reduces damage to the extracellular matrix during freezing. In our study, Achilles tendons of 26 male C57/Bl6 mice were randomized in five groups. Tendons were deep frozen in dimethyl sulfoxide or saline undergoing one or four freeze-thaw-cycles and compared to an unfrozen control group analyzing biomechanical properties, cell viability and collagenous structure. In electron microscopy, collagen fibrils of tendons frozen in saline appeared more irregular in shape, while dimethyl sulfoxide preserved the collagenous structure during freezing. In addition, treatment with dimethyl sulfoxide preserved cell viability visualized with an MTT-Assay, while tendons frozen in saline showed no remaining metabolic activity, indicating total destruction of cells during freezing. The biomechanical results revealed no differences between tendons frozen once in saline or dimethyl sulfoxide. However, tendons frozen four times in saline showed a significantly higher Young's modulus over all strain rates compared to unfrozen tendons. In conclusion, dimethyl sulfoxide preserves the vitality of tendon resident cells and protects the collagenous superstructure during the freezing process resulting in maintained biomechanical properties of the tendon.


Assuntos
Tendão do Calcâneo/efeitos dos fármacos , Criopreservação/métodos , Dimetil Sulfóxido/farmacologia , Módulo de Elasticidade/efeitos dos fármacos , Tendão do Calcâneo/citologia , Tendão do Calcâneo/fisiologia , Animais , Fenômenos Biomecânicos/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Crioprotetores/farmacologia , Módulo de Elasticidade/fisiologia , Masculino , Camundongos Endogâmicos C57BL
9.
Biomed Res Int ; 2019: 8961409, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31011582

RESUMO

Polycaprolactone (PCL) has attracted great attention for bone regeneration attributed to its cost-efficiency, high toughness, and good processability. However, the relatively low elastic modulus, hydrophobic nature, and insufficient bioactivity of pure PCL limited its wider application for bone regeneration. In the present study, the effects of the addition of boron containing bioactive glass (B-BG) materials on the mechanical properties and biological performance of PCL polymer were investigated with different B-BG contents (0, 10, 20, 30, and 40 wt.%), in order to evaluate the potential applications of B-BG/PCL composites for bone regeneration. The results showed that the B-BG/PCL composites possess better tensile strength, human neutral pH value, and fast degradation as compared to pure PCL polymers. Moreover, the incorporation of B-BG could enhance proliferation, osteogenic differentiation, and angiogenic factor expression for rat bone marrow stromal cells (rBMSCs) as compared to pure PCL polymers. Importantly, the B-BG also promoted the angiogenic differentiation for human umbilical vein endothelial cells (HUVECs). These enhanced effects had a concentration dependence of B-BG content, while 30 wt.% B-BG/PCL composites achieved the greatest stimulatory effect. Therefore the 30 wt.% B-BG/PCL composites have potential applications in bone reconstruction fields.


Assuntos
Indutores da Angiogênese/farmacologia , Materiais Biocompatíveis/farmacologia , Regeneração Óssea/efeitos dos fármacos , Boro/farmacologia , Vidro/química , Osteogênese/efeitos dos fármacos , Poliésteres/química , Animais , Materiais Biocompatíveis/química , Linhagem Celular , Módulo de Elasticidade/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana , Humanos , Teste de Materiais/métodos , Células-Tronco Mesenquimais/efeitos dos fármacos , Polímeros/química , Ratos , Ratos Sprague-Dawley , Resistência à Tração/efeitos dos fármacos
10.
Nat Commun ; 10(1): 1186, 2019 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-30862791

RESUMO

Cells select from a diverse repertoire of migration strategies. Recent developments in tunable biomaterials have helped identify how extracellular matrix properties influence migration, however, many settings lack the fibrous architecture characteristic of native tissues. To investigate migration in fibrous contexts, we independently varied the alignment and stiffness of synthetic 3D fiber matrices and identified two phenotypically distinct migration modes. In contrast to stiff matrices where cells migrated continuously in a traditional mesenchymal fashion, cells in deformable matrices stretched matrix fibers to store elastic energy; subsequent adhesion failure triggered sudden matrix recoil and rapid cell translocation. Across a variety of cell types, traction force measurements revealed a relationship between cell contractility and the matrix stiffness where this migration mode occurred optimally. Given the prevalence of fibrous tissues, an understanding of how matrix structure and mechanics influences migration could improve strategies to recruit repair cells to wound sites or inhibit cancer metastasis.


Assuntos
Actomiosina/fisiologia , Movimento Celular/fisiologia , Matriz Extracelular/fisiologia , Resinas Acrílicas/química , Amidas/farmacologia , Animais , Materiais Biocompatíveis/química , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Dextranos/química , Módulo de Elasticidade/efeitos dos fármacos , Fibroblastos , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Humanos , Microscopia Intravital/métodos , Toxinas Marinhas , Teste de Materiais/métodos , Metacrilatos/química , Camundongos , Microscopia Confocal , Células NIH 3T3 , Oxazóis/farmacologia , Piridinas/farmacologia , Imagem com Lapso de Tempo
11.
Biomed Res Int ; 2019: 5109481, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30863779

RESUMO

Background: Acidic beverages, such as soft drinks, can produce erosion of resin composites. The purpose of the present study was to investigate mechanical properties of different esthetic restorative materials after exposure to acidic drink. Methods: Nine different composites were tested: nanofilled (Filtek Supreme XTE, 3M ESPE), microfilled hybrid (G-ænial, GC Corporation), nanohybrid Ormocer (Admira Fusion, Voco), microfilled (Gradia Direct, GC Corporation), microfilled hybrid (Essentia, GC Corporation), nanoceramic (Ceram.X Universal, Dentsply De Trey), supranano spherical hybrid (Estelite Asteria, Tokuyama Dental Corporation), flowable microfilled hybrid (Gradia Direct Flo, GC Corporation), and bulk fill flowable (SureFil SDR flow, Dentsply De Trey). Thirty specimens of each esthetic restorative material were divided into 3 subgroups (n=10): specimens of subgroup 1 were used as control, specimens of subgroup 2 were immersed in 50 ml of Coca Cola for 1 week, and specimens of subgroup 3 were immersed in 50 ml of Coca Cola for 1 month. Flexural strength and elastic modulus were measured for each material with an Instron Universal Testing Machine. Data were submitted to statistical analysis. Results: After distilled water immersion, nanofilled composite showed the highest value of both flexural strength and elastic modulus, but its flexural values decreased after acidic drink immersion. No significant differences were reported between distilled water and acidic drink immersion for all other materials tested both for flexural and for elastic modulus values. Conclusions: Even if nanofilled composite showed highest results, acidic drink immersion significantly reduced flexural values.


Assuntos
Bebidas Gaseificadas/efeitos adversos , Análise do Estresse Dentário , Módulo de Elasticidade/efeitos dos fármacos , Resistência à Flexão/efeitos dos fármacos , Resinas Compostas/química , Materiais Dentários/química , Estética , Humanos , Teste de Materiais , Polimetil Metacrilato/química
12.
J Nanobiotechnology ; 17(1): 32, 2019 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-30797235

RESUMO

BACKGROUND: The conventional approaches to assess the potential cytotoxic effects of nanomaterials (NMs) mainly rely on in vitro biochemical assays. These assays are strongly dependent on the properties of the nanomaterials, for example; specific surface area (SSA), size, surface defects, and surface charge, and the host response. The NMs properties can also interfere with the reagents of the biochemical and optical assays leading to skewed interpretations and ambiguous results related to the NMs toxicity. Here, we proposed a structured approach for cytotoxicity assessment complemented with cells' mechanical responses represented as the variations of elastic Young's modulus in conjunction with conventional biochemical tests. Monitoring the mechanical properties responses at various times allowed understanding the effects of NMs to the filamentous actin cytoskeleton. The elastic Young's modulus was estimated from the force volume maps using an atomic force microscope (AFM). RESULTS: Our results show a significant decrease on Young's modulus, ~ 20%, in cells exposed to low concentrations of graphene flakes (GF), ~ 10% decrease for cells exposed to low concentrations of multiwalled carbon nanotubes (MWCNTs) than the control cells. These considerable changes were directly correlated to the disruption of the cytoskeleton actin fibers. The length of the actin fibers in cells exposed to GF was 50% shorter than the fibers of the cells exposed to MWCNT. Applying both conventional biochemical approach and cells mechanics, we were able to detect differences in the actin networks induced by MWCNT inside the cells and GF outside the cell's membrane. These results contrast with the conventional live/dead assay where we obtained viabilities greater than 80% after 24 h; while the elasticity dramatically decreased suggesting a fast-metabolic stress generation. CONCLUSIONS: We confirmed the production of radical oxygen species (ROS) on cells exposed to CBNs, which is related to the disruption of the cytoskeleton. Altogether, the changes in mechanical properties and the length of F-actin fibers confirmed that disruption of the F-actin cytoskeleton is a major consequence of cellular toxicity. We evidenced the importance of not just nanomaterials properties but also the effect of the location to assess the cytotoxic effects of nanomaterials.


Assuntos
Módulo de Elasticidade/efeitos dos fármacos , Grafite/toxicidade , Nanotubos de Carbono/toxicidade , Células 3T3 , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Adsorção , Animais , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Fibroblastos/citologia , Camundongos , Tamanho da Partícula , Propriedades de Superfície
13.
J Biomech ; 86: 79-88, 2019 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-30770196

RESUMO

Aß1-42, which is highly toxic to neural cells, is commonly present in the brains of people with Alzheimer's disease. In this study, dynamic changes in cell mechanics were monitored under Aß-induced toxicity. To investigate the changes in cellular mechanical properties, we used Aß1-42 oligomer at different concentrations to treat human neuroblastoma SH-SY5H cells. Results demonstrated a two-stage dynamic change in cell mechanics during neurodegeneration. Additionally, Young's modulus (YM) of the treated cells increased in a short period. The reasons include alteration in surface tension, osmotic pressure, and actin polymerization. Rough cellular membranes were observed from atomic force microscope (AFM) measurement. However, the cellular YM gradually decreased when the cells were continuously exposed to Aß1-42 or to a high concentration of Aß1-42. The major reason for the decreased YM was microtubule disassembly. Dynamic change in YM reflects different activities in cytoplasm in response to Aß1-42. The characteristic changes in cell mechanics provided insights into the dynamic neurodegeneration process of cells induced by Aß1-42 oligomer.


Assuntos
Peptídeos beta-Amiloides/farmacologia , Membrana Celular/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Fragmentos de Peptídeos/farmacologia , Linhagem Celular Tumoral , Membrana Celular/ultraestrutura , Módulo de Elasticidade/efeitos dos fármacos , Humanos , Microtúbulos/efeitos dos fármacos , Neurônios/ultraestrutura
14.
Anal Chim Acta ; 1048: 186-193, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30598149

RESUMO

Panax notoginseng saponins (PNS) have shown to be the biologically active constituents responsible for the therapeutic action of panax notoginseng. PNS could help to restrain the oxidative stress, however, whether biomechanical properties of the single cell involve in the protective effect exerted by PNS against oxidative stress injury remains unclear. In this work, we investigated the protective mechanism of PNS against oxidative stress based on the PeakForce Tapping technology firstly, focusing on the biomechanical properties of single human umbilical vascular endothelium cell (HUVEC). PNS display distinct inhibition on the reduction of the young's modulus of cells caused by oxidative stress damage. Combining with immunofluorescence assay, it indicates that improving the stability of cytoskeleton is a significant way for PNS to play a protective role in HUVEC cells during oxidative damage. This work provides a new idea for exploring the functional mechanism of traditional Chinese medicine at the single cell level, and reveals great potential of the atomic force microscope in studying the drug mechanism.


Assuntos
Módulo de Elasticidade/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Panax notoginseng/química , Substâncias Protetoras/farmacologia , Saponinas/farmacologia , Citoesqueleto/efeitos dos fármacos , Medicamentos de Ervas Chinesas/farmacologia , Humanos
15.
Biosci Rep ; 39(1)2019 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-30606743

RESUMO

Recent studies have shown the importance of cell-substrate interaction on neurone outgrowth, where the Young's modulus of the matrix plays a crucial role on the neurite length, migration, proliferation, and morphology of neurones. In the present study, PC12 cells were selected as the representative neurone to be cultured on hydrogel substrates with different stiffness to explore the effect of substrate stiffness on the neurone outgrowth. By adjusting the concentration of gelatin methacryloyl (GelMA), the hydrogel substrates with the variation of stiffnesses (indicated by Young's modulus) from approximately 3-180 KPa were prepared. It is found that the stiffness of GelMA substrates influences neuronal outgrowth, including cell viability, adhesion, spreading, and average neurite length. Our results show a critical range of substrate's Young's modulus that support PC12 outgrowth, and modulate the cell characteristics and morphology. The present study provides an insight into the relationship between the stiffness of GelMA hydrogel substrates and PC12 cell outgrowth, and helps the design and optimization of tissue engineering scaffolds for nerve regeneration.


Assuntos
Neuritos/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Engenharia Tecidual , Tecidos Suporte , Animais , Sobrevivência Celular/efeitos dos fármacos , Módulo de Elasticidade/efeitos dos fármacos , Gelatina/farmacologia , Hidrogéis/administração & dosagem , Hidrogéis/química , Neuritos/metabolismo , Neurônios/classificação , Células PC12 , Ratos
16.
Biochem Biophys Res Commun ; 509(3): 839-844, 2019 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-30638929

RESUMO

Tendon stem/progenitor cells (TSPC) are potential targets for regenerative medicine and the treatment of tendon injuries. The frequency of such injuries increases in elderly patients while the proportion of functional TSPCs in tendon tissue decreases, protracting tendon repair. Using atomic force microscopy (AFM), we show that cell stiffness and size increase in TSPCs isolated from elderly patients (A-TSPC) compared to TSPCs from younger patients (Y-TSPC). Additionally, two-photon excited fluorescence (TPEF) microscopy revealed a denser, well-structured actin cytoskeleton in A-TSPC, which correlates with the augmented cell stiffness. Treating A-TSPC with ROCK-inhibitor, reverses these age-related changes, and has rejuvenating effect on cell morphology and stiffness. We assume that cellular stiffness is a suitable marker for cell aging and ROCK a potential target for therapeutic applications of cell rejuvenation.


Assuntos
Amidas/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Piridinas/farmacologia , Células-Tronco/citologia , Tendões/citologia , Quinases Associadas a rho/antagonistas & inibidores , Adulto , Idoso , Fenômenos Biomecânicos/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Tamanho Celular/efeitos dos fármacos , Células Cultivadas , Senescência Celular/efeitos dos fármacos , Módulo de Elasticidade/efeitos dos fármacos , Humanos , Pessoa de Meia-Idade , Rejuvenescimento , Células-Tronco/efeitos dos fármacos , Células-Tronco/metabolismo , Tendões/efeitos dos fármacos , Tendões/metabolismo , Adulto Jovem , Quinases Associadas a rho/metabolismo
17.
Tissue Eng Part A ; 25(19-20): 1369-1380, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-30632465

RESUMO

Hydrogels represent an attractive material platform for realization of three-dimensional (3D) tissue-engineered constructs, as they have tunable mechanical properties, are compatible with different types of cells, and resemble elements found in natural extracellular matrices. So far, numerous hydrogel-cartilage/bone tissue engineering (TE)-related studies were performed by utilizing a single cell encapsulation approach. Although multicellular spheroid cultures exhibit advantageous properties for cartilage or bone TE, the chondrogenic or osteogenic differentiation potential of stem cell microspheroids within hydrogels has not been investigated much. This study explores, for the first time, how stiffness of gelatin-based hydrogels (having a storage modulus of 538, 3584, or 7263 Pa) affects proliferation and differentiation of microspheroids formed from telomerase-immortalized human adipose-derived stem cells (hASC/hTERT). Confocal microscopy indicates that all tested hydrogels supported cell viability during their 3- to 5-week culture period in the control, chondrogenic, or osteogenic medium. Although in the softer hydrogels cells from neighboring microspheroids started outgrowing and interconnecting within a few days, their protrusion was slower or limited in stiffer hydrogels or those cultured in chondrogenic medium, respectively. High expressions of chondrogenic markers (SOX9, ACAN, COL2A1), detected in all tested hydrogels, proved that the chondrogenic differentiation of hASC/hTERT microspheroids was very successful, especially in the two softer hydrogels, where superior cartilage-specific properties were confirmed by Alcian blue staining. These chondrogenically induced samples also expressed COL10A1, a marker of chondrocyte hypertrophy. Interestingly, the hydrogel itself (with no differentiation medium) showed a slight chondrogenic induction. Regardless of the hydrogel stiffness, in the samples stimulated with osteogenic medium, the expression of selected markers RUNX2, BGLAP, ALPL, and COL1A1 was not conclusive. Nevertheless, the von Kossa staining confirmed the presence of calcium deposits in osteogenically stimulated samples in the two softer hydrogels, suggesting that these also favor osteogenesis. This observation was also confirmed by Alizarin red quantification assay, with which higher amounts of calcium were detected in the osteogenically induced hydrogels than in their controls. The presented data indicate that the encapsulation of adipose-derived stem cell microspheroids in gelatin-based hydrogels show promising potential for future applications in cartilage or bone TE. Impact Statement Osteochondral defects represent one of the leading causes of disability in the world. Although numerous tissue engineering (TE) approaches have shown success in cartilage and bone tissue regeneration, achieving native-like characteristics of these tissues remains challenging. This study demonstrates that in the presence of a corresponding differentiation medium, gelatin-based hydrogels support moderate osteogenic and excellent chondrogenic differentiation of photo-encapsulated human adipose-derived stem cell microspheroids, the extent of which depends on hydrogel stiffness. Because photosensitive hydrogels are a convenient material platform for creating stiffness gradients in three dimensions, the presented microspheroid-hydrogel encapsulation strategy holds promise for future strategies of cartilage or bone TE.


Assuntos
Tecido Adiposo/citologia , Diferenciação Celular/efeitos dos fármacos , Hidrogéis/farmacologia , Esferoides Celulares/citologia , Células-Tronco/citologia , Cálcio/metabolismo , Forma Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Imobilizadas/citologia , Células Imobilizadas/efeitos dos fármacos , Condrogênese/efeitos dos fármacos , Módulo de Elasticidade/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Glicosaminoglicanos/metabolismo , Humanos , Reologia , Esferoides Celulares/efeitos dos fármacos , Células-Tronco/efeitos dos fármacos
18.
Osteoporos Int ; 30(2): 277-285, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30488274

RESUMO

Bone modulus from patients with osteoporosis treated with bisphosphonates for 1 to 20 years was analyzed. Modulus increases during the first 6 years of treatment and remains unchanged thereafter. INTRODUCTION: Bisphosphonates are widely used for treating osteoporosis, but the relationship between treatment duration and bone quality is unclear. Since material properties partially determine bone quality, the present study quantified the relationship between human bone modulus and hardness with bisphosphonate treatment duration. METHODS: Iliac crest bone samples from a consecutive case series of 86 osteoporotic Caucasian women continuously treated with oral bisphosphonates for 1.1-20 years were histologically evaluated to assess bone turnover and then tested using nanoindentation. Young's modulus and hardness were measured and related to bisphosphonate treatment duration by statistical modeling. RESULTS: All bone samples had low bone turnover. Statistical models showed that with increasing bisphosphonate treatment duration, modulus and hardness increased, peaked, and plateaued. These models used quadratic terms to model modulus increases from 1 to 6 years of bisphosphonate treatment and linear terms to model modulus plateaus from 6 to 20 years of treatment. The treatment duration at which the quadratic-linear transition (join point) occurred also depended upon trabecular location. Hardness increased and peaked at 12.4 years of treatment; it remained constant for the next 7.6 years of treatment and was insensitive to trabecular location. CONCLUSIONS: Bone modulus increases with bisphosphonate treatment durations up to 6 years, no additional modulus increases occurred after 6 years of treatment. Although hardness increased, peaked at 12.4 years and remained constant for the next 7.6 years of BP treatment, the clinical relevance of hardness remains unclear.


Assuntos
Osso Esponjoso/efeitos dos fármacos , Difosfonatos/farmacologia , Osteoporose Pós-Menopausa/tratamento farmacológico , Administração Oral , Idoso , Remodelação Óssea/efeitos dos fármacos , Osso Esponjoso/patologia , Osso Esponjoso/fisiopatologia , Estudos Transversais , Difosfonatos/administração & dosagem , Difosfonatos/uso terapêutico , Esquema de Medicação , Módulo de Elasticidade/efeitos dos fármacos , Feminino , Dureza/efeitos dos fármacos , Humanos , Ílio/efeitos dos fármacos , Ílio/patologia , Ílio/fisiopatologia , Pessoa de Meia-Idade , Osteoporose Pós-Menopausa/patologia , Osteoporose Pós-Menopausa/fisiopatologia , Fotomicrografia
19.
Oncol Rep ; 41(2): 928-938, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30535459

RESUMO

There is a growing interest in the fact that mechanical signals may be as important as biological signals in evaluating cell viability. To investigate the alterations in biomechanics, nanomorphology and biological apoptotic signals during early apoptosis, an apoptosis model was established for cervical cancer HeLa cells induced by cytochalasin B (CB). The cellular mechanical properties, geometry, morphology and expression of key apoptotic proteins were systematically analyzed. The findings indicated a marked decline in cellular elastic modulus and volume and a considerable increase in surface roughness occurring prior to the activation of biological apoptosis signals (such as phosphatidylserine exposure or activation of CD95/Fas). Moreover, the depolymerization of filamentous actin aggravated the intracellular crowding degree, which induced the redistribution of different­sized protein molecules and protrusions across the cell membrane arising from excluded volume interactions. Statistical analysis revealed that the disassembly of the actin cytoskeleton was negatively correlated with the cellular elastic modulus and volume, but was positively correlated with surface roughness and CD95/Fas activation. The results of the present study suggest that compared with biological signals, mechanical and geometrical reconstruction is more sensitive during apoptosis and the increase in cell surface roughness arises from the redistribution of biophysical molecules. These results contribute to our in­depth understanding of the apoptosis mechanisms of cancer cells mediated by cytochalasin B.


Assuntos
Citoesqueleto de Actina/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Citocalasina B/farmacologia , Receptor fas/metabolismo , Citoesqueleto de Actina/metabolismo , Citoesqueleto de Actina/ultraestrutura , Actinas/metabolismo , Actinas/ultraestrutura , Linhagem Celular Tumoral , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Módulo de Elasticidade/efeitos dos fármacos , Feminino , Células HeLa , Humanos , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Neoplasias do Colo do Útero/tratamento farmacológico , Neoplasias do Colo do Útero/patologia
20.
Biotechnol J ; 14(3): e1700768, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29802760

RESUMO

Vascular tissue engineering combines cells with scaffold materials in vitro aiming the development of physiologically relevant vascular models. For natural scaffolds such as collagen gels, where cells can be mixed with the material solution before gelation, cell seeding density is a key parameter that can affect extracellular matrix deposition and remodeling. Nonetheless, this parameter is often overlooked and densities sensitively lower than those of native tissues, are usually employed. Herein, the effect of seeding density on the maturation of tubular collagen gel-based scaffolds cellularized with smooth muscle cells is investigated. The compaction, the expression, and deposition of key vascular proteins and the resulting mechanical properties of the constructs are evaluated up to 1 week of maturation. Results show that increasing cell seeding density accelerates cell-mediated gel compaction, enhances elastin expression (more than sevenfold increase at the highest density, Day 7) and finally improves the overall mechanical properties of constructs. Of note, the tensile equilibrium elastic modulus, evaluated by stress-relaxation tests, reach values comparable to native arteries for the highest cell density, after a 7-day maturation. Altogether, these results show that higher cell seeding densities promote the rapid maturation of collagen gel-based vascular constructs toward structural and mechanical properties better mimicking native arteries.


Assuntos
Colágeno/metabolismo , Elastina/metabolismo , Géis/metabolismo , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/fisiologia , Materiais Biocompatíveis/farmacologia , Prótese Vascular , Contagem de Células/métodos , Células Cultivadas , Módulo de Elasticidade/efeitos dos fármacos , Matriz Extracelular/metabolismo , Matriz Extracelular/fisiologia , Humanos , Teste de Materiais/métodos , Miócitos de Músculo Liso/efeitos dos fármacos , Estresse Mecânico , Resistência à Tração/fisiologia , Engenharia Tecidual/métodos , Tecidos Suporte
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