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Cardiovascular diseases are major diseases, and there is lack of artificial blood vessels with small diameters which can be applied in coronary artery bypass surgery. The conventional vascular scaffold preparation techniques in tissue engineering have shortcomings in regulating the diameter, geometric shape, and interconnectivity of the scaffold. 3D bioprinting can simulate the natural structure of the vascular tissue, accurately print live cells and biomaterials, and regulate the microstructure and porosity of scaffolds on the nanoscale, providing new ideas for vascular tissue engineering. This article systematically evaluates the classification of 3D bioprinting technologies and reviews the latest research progress of 3D bioprinting in vascular tissue engineering. It summarizes the advantages of 3D bioprinting and points out the problems that need to be solved, such as the immune rejection of blood vessel materials, providing reference for the further research.
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Bioimpressão , Impressão Tridimensional , Engenharia Tecidual , Alicerces Teciduais , Engenharia Tecidual/métodos , Alicerces Teciduais/química , Humanos , Vasos Sanguíneos , Materiais Biocompatíveis , Prótese VascularRESUMO
Removing free hemoglobin generated during extracorporeal circulation remains a challenge. Currently, there is no adsorbent with specificity and good biosafety for removing hemoglobin. In this study, a new chitosan/sodium alginate/carbon nitride (CS/SA/C3N4) hydrogel adsorbent was prepared by blending SA with C3N4 to drop into CS/CaCl2 solution. The physicochemical properties of CS/SA/C3N4 hydrogel were evaluated using some techniques, including scanning electron microscope, Zeta potential measurement, and thermogravimetric analysis. Hemoglobin adsorption in vitro, stability, hemocompatibility, cell compatibility, inflammatory reaction and blood extracorporeal circulation in vivo were also evaluated. The findings revealed that the CS/SA/C3N4-0.4 % hydrogel exhibited an impressive adsorption capacity of 142.35 mg/g for hemoglobin. The kinetic data of hemoglobin adsorption were well-described by pseudo second-order model, while the isothermal model data conformed to the Langmuir model. The hardness and modulus of CS/SA/C3N4-0.4 % was 11.7 KPa and 94.66 KPa respectively, which indicated robust resistance to breakage. CS/SA/C3N4 demonstrated excellent hemocompatibility, biocompatibility and anti-inflammatory properties. In addition, the results of in vivo rabbit extracorporeal blood circulation experiment demonstrated that CS/SA/C3N4 could adsorb free hemoglobin from blood while maintaining high biosafety standard. Consequently, CS/SA/C3N4 hydrogel emerges as a promising candidate for use as a hemoglobin adsorbent in extracorporeal blood circulation system.
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Alginatos , Quitosana , Hemoglobinas , Hidrogéis , Nitrilas , Quitosana/química , Hemoglobinas/química , Alginatos/química , Adsorção , Hidrogéis/química , Animais , Coelhos , Nitrilas/química , Humanos , CinéticaRESUMO
This study was designed to evaluate the efficiency of the combination of autologous platelet-rich plasma gel (APG) and Manuka honey gauze in the treatment of Stages 3-4 pressure injury of older adults. Patients were divided into four groups: Manuka honey gauze and APG (M + A), Manuka honey gauze (M), APG (A), and a control group (C). Different treatments were given, then wound bed coverage with granulation tissue, wound size reduction, and Pressure Ulcer Scale for Healing (PUSH) score were examined. Paraffin-embedded sections of wound tissues were analyzed and wound swab cultures were assessed. Kruskal-Wallis test and Mann-Whitney U test were performed in statistical analysis at a 5% significance level. A total of 42 patients were accepted. Significant increase of wound bed coverage with granulation tissue (51.24%, P = .004, Kruskal-Wallis test) and decrease of PUSH score (-5) were observed in the M + A group at the end of the observation (P = .032, Mann-Whitney U test). The hematoxylin-eosin staining of wound tissues showed that typical squamous epithelium was seen in wound bed of patient in M + A group. Manuka honey gauze and APG were proved to be superior treatments for pressure injury of old patient. Increase of granulation tissue coverage, reduction of PUSH score, and improved growth of epithelium were observed in M + A group. There was no side-effect, and the treatment would not cause infection.
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The challenge in China is to retain high yields while lowering greenhouse gas (GHG) emissions in the context of the increasing global and Chinese demand for rice yield. Better fertilizer management is a key factor that favors intensive rice systems toward more intensive, diverse, and sustainable development to obtain higher yield and environmental benefits. Thus, we used a data-intensive approach to estimate yield, fertilizer productivity (FP) and GHG emissions based on fertilizer and soil characteristics across major Chinese rice-producing regions. The common rice production model showed medium yield, low emission intensity and FP, and low or high GHG emissions. Approximate 41 % and 10 %, 34 % and 3 %, 8 % and 2 %, and 8 % and 1 % probabilities for medium and high yield (MY and HY)-low emission intensity (LI)-low GHG emissions (LG)-high FP (HF) (MY-LI-LG-HF and HY-LI-LG-HF) were achieved in Northeast, South, Southwest, Central and East China, respectively, by adjusting basal, tillering and panicle fertilization and soil pH, N, P and K. Our results provide insights for adjusting soil nutrient traits and fertilizer inputs according to regional production potentials for higher yields and FP and lower GHG emissions in China.
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BACKGROUND: Internal fixation with cephalomedullary nails has been widely used in the treatment of intertrochanteric femoral fractures (IFF). Yet, the difference in efficacy and safety between the commonly used integrated dual-screw cephalomedullary nail (InterTAN) and single-screw cephalomedullary nail remains inconclusive. Thus we performed the present systematic review and meta-analysis. METHODS: Randomized controlled trials (RCTs) or observational studies comparing InterTAN with proximal femoral nail anti-rotation (PFNA), the Asian PFNA (PFNA-II), or the Gamma3 nail in treating IFF were searched on PubMed, EMBASE, Web of Science and Cochrane Library from inception to April 30, 2023. The differences in perioperative parameters and clinical and radiological outcomes were evaluated by mean difference (MD) with 95% confidence interval (95%CI). The risks of various complications and mortality were assessed by risk ratio (RR) with 95%CI. RESULTS: Twenty-three studies comprising 3566 patients were included. Compared with single-screw cephalomedullary nails (PFNA/PFNA-II, Gamma3), InterTAN conferred significantly reduced risk of implant failures (RR = 0.37, 95%CI 0.26 to 0.51, P < 0.001), hip and thigh pain (RR = 0.70, 95%CI 0.55 to 0.90, P = 0.006) and all-cause revision/reoperation (RR = 0.38, 95%CI 0.26 to 0.57, P < 0.001). Moreover, patients treated with InterTAN had significantly higher 1-year Harris Hip Score (MD = 0.82, 95%CI 0.20-1.44, P = 0.010) and shorter time to union/healing (MD = - 0.66 days, 95%CI - 1.16 to - 0.16, P = 0.009). Femoral neck shortening, time to full bearing, and incidences of non-union, infection, deep venous thrombosis, and mortality were comparable between both groups. CONCLUSIONS: The integrated dual-screw InterTAN construct has superior performance in reducing risks of complications and improving clinical and functional outcomes in the treatment of IFF. More well-designed, high-quality RCTs are warranted to confirm these findings.
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Fraturas do Quadril , Humanos , Fraturas do Quadril/cirurgia , Colo do Fêmur , Cicatrização , Parafusos Ósseos , FêmurRESUMO
Cyclic electron flow around photosystem I (CEF-PSI) is shown to be an important protective mechanism to photosynthesis in cotton leaves. However, it is still unclear how CEF-PSI is regulated in non-foliar green photosynthetic tissues such as bracts. In order to learn more about the regulatory function of photoprotection in bracts, we investigated the CEF-PSI attributes in Yunnan 1 cotton genotypes (Gossypium bar-badense L.) between leaves and bracts. Our findings demonstrated that cotton bracts possessed PROTON GRADIENT REGULATION5 (PGR5)-mediated and the choroplastic NAD(P)H dehydrogenase (NDH)-mediated CEF-PSI by the same mechanism as leaves, albeit at a lower rate than in leaves. The ATP synthase activity of bracts was also lower, while the proton gradient across thylakoid membrane (ΔpH), rate of synthesis of zeaxanthin, and heat dissipation were higher than those of the leaves. These results imply that cotton leaves under high light conditions primarily depend on CEF to activate ATP synthase and optimize ATP/NADPH. In contrast, bracts mainly protect photosynthesis by establishing a ΔpH through CEF to stimulate the heat dissipation process.
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Gossypium , Prótons , Transporte de Elétrons , Gossypium/genética , Gossypium/metabolismo , Elétrons , China , Fotossíntese/fisiologia , Complexo de Proteína do Fotossistema I/metabolismo , Trifosfato de Adenosina , Luz , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/metabolismoRESUMO
Crop domestication for increasing growth rates and yields appears to have altered the features of adaxial and abaxial stomata, but its effect on leaf water use efficiency (WUE) have not been experimentally verified. In this study, we characterized stomatal anatomy and carbon isotope discrimination (δ13C) in 32 wild and 36 domesticated genotypes of cotton grown under agricultural field conditions. The results showed that domesticated genotypes possessed lower WUE, as indicated by low or more negative δ13C compared with wild genotypes. Higher theoretical maximum stomatal conductance (gsmax) after domestication was accounted for by more stomata rather than significantly enlarged stomata. Specifically, abaxial stomatal density was higher whilst there was no change in the adaxial density. The size of both adaxial and abaxial stomata was greater due to larger guard cells but without there being any increase in pore size. However, there was a negative relationship between δ13C and stomatal size across wild and domesticated genotypes, especially on the abaxial leaf surface, because bigger stomata resulted in a lower maximum stomatal response rate to fluctuating canopy light, resulting in increased water loss. Overall, our results indicate that cotton domestication has resulted in substantial variation in stomatal anatomy, and that WUE and drought tolerance can potentially be improved in future breeding by decreasing the size of abaxial stomata to produce a faster stomatal response and hence a reduction in unnecessary water loss.
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Estômatos de Plantas , Água , Estômatos de Plantas/fisiologia , Domesticação , Melhoramento Vegetal , Folhas de Planta/fisiologiaRESUMO
Tissue engineering is an alternative method for preparing small-caliber (<6 mm) vascular grafts. Dynamic mechanical conditioning is being researched as a method to improve mechanical properties of tissue engineered blood vessels. This method attempts to induce unique reaction in implanted cells that regenerate the matrix around them, thereby improving the overall mechanical stability of the grafts. In this study, we used a bioreactor to seed endothelial cells and smooth muscle cells into the inner and outer layers of the electrospun spider silk protein scaffold respectively to construct vascular grafts. The cell proliferation, mechanical properties, blood compatibility and other indicators of the vascular grafts were characterized in vitro. Furthermore, the vascular grafts were implanted in Sprague Dawley rats, and the vascular grafts' patency, extracellular matrix formation, and inflammatory response were evaluated in vivo. We aimed to construct spider silk protein vascular grafts with the potential for in vivo implantation by using a pulsating flow bioreactor. The results showed that, when compared with the static culture condition, the dynamic culture condition improved cell proliferation on vascular scaffolds and enhanced mechanical function of vascular scaffolds. In vivo experiments also showed that the dynamic culture of vascular grafts was more beneficial for the extracellular matrix deposition and anti-thrombogenesis, as well as reducing the inflammatory response of vascular grafts. In conclusion, dynamic mechanical conditioning aid in the resolution of challenges impeding the application of electrospun scaffolds and have the potential to construct small-caliber blood vessels with regenerative function for cardiovascular tissue repair.
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Seda , Engenharia Tecidual , Ratos , Animais , Engenharia Tecidual/métodos , Alicerces Teciduais , Células Endoteliais , Ratos Sprague-Dawley , Prótese VascularRESUMO
ABSTRACT: Background and aims: Genipin, an iridoid derived from geniposide by ß-glucosidase hydrolysis, has shown potential benefit in the treatment of heart function insufficiency despite its unclear therapeutic mechanism. This study aimed to investigate the primary cardioprotective mechanism of genipin. We hypothesized that genipin demonstrated the antiapoptosis and anti-inflammation for cardiac protection by inhibiting the cyclooxidase 2 (COX2)-prostaglandin D2 (PGD2) and murine double minute 2 (MDM2)-p53 pathways. Methods: The normal Sprague-Dawley rats were made into myocardial infarction models by conventional methods. Animals were treated with genipin for 5 weeks after myocardial infarction (MI). Morphometric and hemodynamic measurements were performed 5 weeks post-MI. Biological and molecular experiments were performed after the termination. Results: Both morphometry and hemodynamics in systole and diastole were significantly impaired in the model group but restored close to basal level after treatment with genipin. Genipin also restored the post-MI upregulated expressions of cytochrome c, p53, COX2, and PGD2 and downregulated expression of MDM2 to the approximate baseline. Genipin inhibited apoptotic and inflammatory pathways to prevent post-MI structure-function remodeling. Conclusions: This study showed the cardioprotective mechanism of genipin and implied its potential clinical application for the treatment of ischemic heart failure.
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Insuficiência Cardíaca , Infarto do Miocárdio , Animais , Ratos , Ciclo-Oxigenase 2 , Iridoides/farmacologia , Iridoides/uso terapêutico , Infarto do Miocárdio/tratamento farmacológico , Prostaglandina D2 , Ratos Sprague-Dawley , Transdução de Sinais , Proteína Supressora de Tumor p53RESUMO
This paper explores the effectiveness of predictors, including nine economic policy uncertainty indicators, four market sentiment indicators and two financial stress indices, in predicting the realized volatility of the S&P 500 index. We employ the MIDAS-RV framework and construct the MIDAS-LASSO model and its regime switching extension (namely, MS-MIDAS-LASSO). First, among all considered predictors, the economic policy uncertainty indices (especially the equity market volatility index) and the CBOE volatility index are the most noteworthy predictors. Although the CBOE volatility index has the best predictive ability for stock market volatility, its predictive ability has weakened during the COVID-19 epidemic, and the equity market volatility index is best during this period. Second, the MS-MIDAS-LASSO model has the best predictive performance compared to other competing models. The superior forecasting performance of this model is robust, even when distinguishing between high- and low-volatility periods. Finally, the prediction accuracy of the MS-MIDAS-LASSO model even outperforms the traditional LASSO strategy and its regime switching extension. Furthermore, the superior predictive performance of this model has not changed with the outbreak of the COVID-19 epidemic.
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The incidence rate of cardiovascular diseases is increasing year by year. The demand for coronary artery bypass grafting has been very large. Acellular blood vessels have potential clinical application because of their natural vascular basis, but their biocompatibility and anticoagulant energy need to be improved. We decellularized the abdominal aorta of SD rats, and then modified with bivalirudin via polydopamine. The mechanical properties, blood compatibility, cytocompatibility, immune response, and anticoagulant properties were evaluated, and then the bivalirudin-modified acellular blood vessels were implanted into rats for remodeling evaluation in vivo. The results we got show that the bivalirudin-modified acellular blood vessels showed good cytocompatibility and blood compatibility, and its anti-inflammatory trend was dominant in the immune response. After 3 months of transplantation, the bivalirudin-modified acellular blood vessels did not easily form thrombus. It was not easy to form calcification and could make the host cells grow better. Through vascular stimulation and immunofluorescence test, we found that vascular smooth muscle cells and endothelial cells proliferated well in the bivalirudin group. Bivalirudin-modified acellular blood vessels provided new idea for small diameter tissue engineering blood vessels, and may become a potential clinical substitute for small-diameter vascular grafts.
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Células Endoteliais , Hirudinas , Animais , Prótese Vascular , Vasos Sanguíneos , Hirudinas/farmacologia , Fragmentos de Peptídeos , Ratos , Ratos Sprague-Dawley , Proteínas Recombinantes , Engenharia Tecidual/métodosRESUMO
In this study, we focus on the role of jumps and leverage in predicting the realized volatility (RV) of China's crude oil futures. We employ a standard mixed data sampling (MIDAS) modeling framework. First, the in-sample results indicate that the jump and leverage effects are useful in predicting the RV of Chinese crude oil futures. Second, the out-of-sample results suggest that jump has very significant predictive power at the one-day-ahead horizon while the leverage effect contains more useful information for long-term predictions. Moreover, our results are supported by a number of robustness checks. Finally, we find new evidence that the prediction model that considers the leverage effect has the best predictive power during the COVID-19 pandemic.
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In this paper, we explore the dynamics of the return connectedness among major commodity assets (crude oil, gold and corn) and financial assets (stock, bond and currency) in China and the US during recent COVID-19 pandemic by using the time-varying connectedness measurement introduced by Antonakakis et al. (2020). Firstly, we find that the total return connectedness of the US commodity and financial assets is stronger than that of the Chinese commodity and financial assets in most cases, and both of them increase rapidly after the outbreak of COVID-19. Secondly, gold is a net transmitter of return shocks in both the Chinese and the US markets before the burst of COVID-19 pandemic, while stock and currency become net transmitters of shocks in both markets after that. Thirdly, corn usually receives the shocks from other commodity and financial assets in both China and the US markets during the COVID-19 epidemic, and the shocks it receives peak during this period, making it the strongest net receiver of shocks. Fourthly, crude oil shifts from a net transmitter to a net receiver of shocks in China after the outbreak of COVID-19, but it remains to be a net transmitter of shocks in the US. Finally, bond changes from a net receiver to a net transmitter of shocks in China after the outbreak of the epidemic, but converts from a net transmitter to a net receiver of shock in the US. The interchangeable roles of the commodity and financial assets suggest flexible regulatory and portfolio allocation strategies should be applied by policy makers and investors.
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Understanding the impact of infectious disease pandemic on stock market volatility is of great concerns for investors and policy makers, especially during recent new coronavirus spreading period. Using an extended GARCH-MIDAS model and a newly developed Infectious Disease Equity Market Volatility Tracker (EMV-ID), we investigate the effects of infectious disease pandemic on volatility of US, China, UK and Japan stock markets through January 2005 to April 2020. The empirical results show that, up to 24-month lag, infectious disease pandemic has significant positive impacts on the permanent volatility of international stock markets, even after controlling the influences of past realized volatility, global economic policy uncertainty and the volatility leverage effect. At different lags of eruptions in infectious disease pandemic, EMV-ID has distinct effects on various stock markets while it has the smallest impact on permanent volatility of China's stock market.
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The success of artificial vascular graft in the host to obtain functional tissue regeneration and remodeling is a great challenge in the field of small diameter tissue engineering blood vessels. In our previous work, poly(ε-caprolactone) (PCL)/fibrin vascular grafts were fabricated by electrospinning. It was proved that the PCL/fibrin vascular graft was a suitable small diameter tissue engineering vascular scaffold with good biomechanical properties and cell compatibility. Here we mainly examined the performance of PCL/fibrin vascular graft in vivo. The graft showed randomly arranged nanofiber structure, excellent mechanical strength, higher compliance and degradation properties. At 9 months after implantation in the rat abdominal aorta, the graft induced the regeneration of neoarteries, and promoted ECM deposition and rapid endothelialization. More importantly, the PCL/fibrin vascular graft showed more microvessels density and fewer calcification areas at 3 months, which was beneficial to improve cell infiltration and proliferation. Moreover, the ratio of M2/M1macrophage in PCL/fibrin graft had a higher expression level and the secretion amount of pro-inflammatory cytokines started to increase, and then decreased to similar to the native artery. Thus, the electrospun PCL/fibrin tubular vascular graft had great potential to become a new type of artificial blood vessel scaffold that can be implanted in vivo for long term.
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Fibrina , Enxerto Vascular , Animais , Prótese Vascular , Poliésteres , Ratos , Engenharia Tecidual , Alicerces TeciduaisRESUMO
PURPOSE: The development of tissue-engineered blood vessels provides a new source of donors for coronary artery bypass grafting and peripheral blood vessel transplantation. Fibrin fiber has good biocompatibility and is an ideal tissue engineering vascular scaffold, but its mechanical property needs improvement. METHODS: We mixed polyurethane (PU) and fibrin to prepare the PU/fibrin vascular scaffolds by using electrospinning technology in order to enhance the mechanical properties of fibrin scaffold. We investigated the morphological, mechanical strength, hydrophilicity, degradation, blood and cell compatibility of PU/fibrin (0:100), PU/fibrin (5:95), PU/fibrin (15:85) and PU/fibrin (25:75) vascular scaffolds. Based on the results in vitro, PU/fibrin (15:85) was selected for transplantation in vivo to repair vascular defects, and the extracellular matrix formation, vascular remodeling, and immune response were evaluated. RESULTS: The results indicated that the fiber diameter of the PU/fibrin (15:85) scaffold was about 712nm. With the increase of PU content, the mechanical strength of the composite scaffolds increased, however, the degradation rate decreased gradually. The PU/fibrin scaffold showed good hydrophilicity and hemocompatibility. PU/fibrin (15:85) vascular scaffold could promote the adhesion and proliferation of mesenchymal stromal cells (MSCs). Quantitative RT-PCR experimental results showed that the expression of collagen, survivin and vimentin genes in PU/fibrin (15:85) was higher than that in PU/fibrin (25:75). The results in vivo indicated the mechanical properties and compliance of PU/fibrin grafts could meet clinical requirements and the proportion of thrombosis or occlusion was significantly lower. The graft showed strong vasomotor response, and the smooth muscle cells, endothelial cells, and ECM deposition of the neoartery were comparable to that of native artery after 3 months. At 3 months, the amount of macrophages in PU/fibrin grafts was significantly lower, and the secretion of pro-inflammatory and anti-inflammatory cytokines decreased. CONCLUSION: PU/fibrin (15:85) vascular scaffolds had great potential to be used as small-diameter tissue engineering blood vessels.
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Prótese Vascular , Fibrina/química , Poliuretanos/química , Alicerces Teciduais/química , Animais , Adesão Celular , Células Endoteliais , Expressão Gênica , Masculino , Teste de Materiais , Células-Tronco Mesenquimais/citologia , Miócitos de Músculo Liso/citologia , Ratos Sprague-Dawley , Engenharia Tecidual/métodosRESUMO
Megaselia spiracularis Schmitz, 1938 (Diptera: Phoridae) is a pest that often appears in human living areas where it can spread pathogens. Besides, the species is of forensic value. Currently, studies focusing on the development of this species are limited. Understanding the developmental patterns of M. spiracularis, therefore, is important for controlling populations of this pest and for estimating the minimum postmortem interval (PMImin). Here, we studied the development of M. spiracularis exposed to seven constant temperatures ranging from 16 to 34 °C. The developmental durations, accumulated degree hours and larval body length changes were measured. Three kinds of development models that can be used to estimate the PMImin were established, including isomorphen diagram, isomegalen diagram and thermal summation model. The duration of M. spiracularis development at 16, 19, 22, 25, 28, 31 and 34 °C from egg to adult stage were 1131.1 ± 34.5, 807.3 ± 9.3, 529.6 ± 1.8, 367.0 ± 8.8, 302.4 ± 7.0, 250.0 ± 2.1 and 232.6 ± 1.9 h, respectively. The developmental threshold temperature and the thermal summation constant were estimated as 12.0 ± 0.5 °C and 4989.7 ± 308.9° hours, respectively. A general model represented by a logistic equation describing how larval body length will change with the time after hatching was fit to data. The present study provides basic developmental data of M. spiracularis, which can be used for achieving better control of this noxious insect as well as for estimation of its PMImin at different temperatures.
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Dípteros/crescimento & desenvolvimento , Entomologia Forense/métodos , Temperatura , Animais , Larva/crescimento & desenvolvimentoRESUMO
Previous studies have proved that fibrin is an excellent scaffold material for tissue engineered blood vessel. However, the mechanical properties of fibrin are not enough. One way to solve the problem is to combine polymer materials with fibrin to enhance its biomechanical properties. In this study, a novel polycaprolactone (PCL)/fibrin composite scaffold was prepared by electrospinning technology. The morphological, physicochemical analysis, blood compatibility, biomechanical properties, biocompatibility and biodegradability of this vascular scaffold were evaluated. The results showed that electrospun PCL/fibrin scaffold possessed smaller aperture and larger fiber diameter than that of fibrin scaffold. The swelling ratio of the vascular PCL/fibrin scaffold at (0:100), (10:90), (20:80) and (30:70) was 112 ± 5.3, 103 ± 6.9, 94 ± 5.9 and 89 ± 3.4%, respectively. Mechanical properties of fibrin scaffolds were enhanced significantly by the addition of PCL. Furthermore, the time of plasma re-calcification, activated partial thromboplastin time and thromboplastin time in four different proportions of PCL/fibrin scaffolds were similar to that of the control group. Degradation experiments in vitro demonstrated that the degradation rate of PCL/fibrin scaffold was closely related to the content of PCL. MTT assays and immunofluorescence staining indicated that the stem cells cocultured with the PCL/fibrin scaffold had good proliferation behavior. Live/dead assay confirmed that the number of MSCs in the PCL/fibrin (10:90) group was significantly increased as compared to other groups. The tests in vivo results showed PCL/fibrin scaffold could promote cell infiltration and tissue regeneration and its degradation in vivo was faster than that of PCL scaffold. In summary, PCL/fibrin (20:80) scaffold exhibited balanced mechanical properties and degradability, as well as good cell compatibility properties; therefore, it was a promising tissue engineering material for vascular graft.
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Materiais Biocompatíveis/química , Materiais Biocompatíveis/toxicidade , Fibrina/química , Fibrina/toxicidade , Teste de Materiais , Fenômenos Mecânicos , Poliésteres/química , Humanos , Tempo de Tromboplastina Parcial , Engenharia TecidualRESUMO
In order to improve the thermal oxidation resistance of carbon fiber-reinforced porous silicon oxycarbide (SiCO) ceramic composites, an Al2O3-containing TaSi2-MoSi2-borosilicate glass coating was formed on the surface of the composites via brushing and sintering. The anti-oxidation property of the coated composites at 1873 K was investigated. Microstructures and chemical compositions of the sample before and after anti-oxidation test were determined using XRD, SEM and EDS. After heating in air at 1873 K for 20 min, the Al2O3-containing TaSi2-MoSi2-borosilicate glass coating effectively protects the SiCO ceramic composites and the coated sample kept its appearance well without obvious defects on the surface. The cross-sectional SEM images show that the coating is covered by a film of oxidation products with a thickness of about 40 µm, which is dense and crack free. Inside the A-TMG coating, irregular-shaped silicides are surrounded by continuous borosilicate glass and no penetrating holes or visible cracks are found. Al2O3 increases the viscosity of the borosilicate glass, which improves oxidation resistance of the coated sample by enhancing gas-penetration resistance of the glass. In contrast, the sample without Al2O3 in the coating slurry is severely oxidized and exhibits lots of open pores on the surface after oxidation test.