Replicating endothelial shear stress in organ-on-a-chip for predictive hypericin photodynamic efficiency.

Photodynamic therapy using Hypericin (Hy-PDT) is an alternative non-invasive treatment that enables selective tumor inhibition and angiogenesis derived from the differential recruitment of endothelial cells in the tumor microenvironment. Most PDT studies were performed on in vitro models without vascular biomechanical simulation. Our work strives to develop a microchip that generates a constant shear stress force to investigate the Hy-PDT efficiency on human umbilical vein endothelial cells (HUVECs). The microchip with a single straight microchannel was composed of the bottom layer (polystyrene), the middle layer (double-sided biocompatible adhesive tape), and the top layer (polyester film) and could produce shear stress in the range of 1.4 - 7.0 dyn cm-2. The quantification of vascular endothelial growth factor (VEGF), cell viability, and activities of caspases 3 and 7 were assayed to validate the microchip and Hy-PDT efficacy. After the endothelization, static and dynamic cell incubations with Hy were conducted in microchips. Compared to static systems, the shear stress displayed its effect on the increasing release of VEGF and promoted more cell damage and cell death via necrosis during Hy-PDT. In conclusion, the expressive shear stress-dependent manner during PDT treatments suggests that the microchip could be an essential approach in preclinical tests to evaluate the therapeutic outcome considering the endothelial shear stress microenvironment.

Rapid Fabrication of Microfluidic Devices for Biological Mimicking: A Survey of Materials and Biocompatibility.

Microfluidics is an essential technique used in the development of in vitro models for mimicking complex biological systems. The microchip with microfluidic flows offers the precise control of the microenvironment where the cells can grow and structure inside channels to resemble in vivo conditions allowing a proper cellular response investigation. Hence, this study aimed to develop low-cost, simple microchips to simulate the shear stress effect on the human umbilical vein endothelial cells (HUVEC). Differentially from other biological microfluidic devices described in the literature, we used readily available tools like heat-lamination, toner printer, laser cutter and biocompatible double-sided adhesive tapes to bind different layers of materials together, forming a designed composite with a microchannel. In addition, we screened alternative substrates, including polyester-toner, polyester-vinyl, glass, Permanox® and polystyrene to compose the microchips for optimizing cell adhesion, then enabling these microdevices when coupled to a syringe pump, the cells can withstand the fluid shear stress range from 1 to 4 dyne cm2. The cell viability was monitored by acridine orange/ethidium bromide (AO/EB) staining to detect live and dead cells. As a result, our fabrication processes were cost-effective and straightforward. The materials investigated in the assembling of the microchips exhibited good cell viability and biocompatibility, providing a dynamic microenvironment for cell proliferation. Therefore, we suggest that these microchips could be available everywhere, allowing in vitro assays for daily laboratory experiments and further developing the organ-on-a-chip concept.

Potential application of rLc36 protein for diagnosis of canine visceral leishmaniasis.

Visceral leishmaniasis (VL) is fatal if left untreated. Infected dogs are important reservoirs of the disease, and thus specific identification of infected animals is very important. Several diagnostic tests have been developed for canine VL (CVL); however, these tests show varied specificity and sensitivity. The present study describes the recombinant protein rLc36, expressed by Leishmania infantum, as potential antigen for more sensitive and specific diagnosis of CVL based on an immunoenzymatic assay. The concentration of 1.0 µg/mL of rLc36 enabled differentiation of positive and negative sera and showed a sensitivity of 85% and specificity of 71% (with 95% confidence), with an accuracy of 76%.

Endothelial Cell Culture Under Perfusion On A Polyester-Toner Microfluidic Device.

This study presents an inexpensive and easy way to produce a microfluidic device that mimics a blood vessel, serving as a start point for cell culture under perfusion, cardiovascular research, and toxicological studies. Endpoint assays (i.e., MTT reduction and NO assays) were used and revealed that the components making up the microchip, which is made of polyester and toner (PT), did not induce cell death or nitric oxide (NO) production. Applying oxygen plasma and fibronectin improved the adhesion and proliferation endothelial cell along the microchannel. As expected, these treatments showed an increase in vascular endothelial growth factor (VEGF-A) concentration profiles, which is correlated with adherence and cell proliferation, thus promoting endothelialization of the device for neovascularization. Regardless the simplicity of the device, our "vein-on-a-chip" mimetic has a potential to serve as a powerful tool for those that demand a rapid microfabrication method in cell biology or organ-on-a-chip research.

Metabolic profiling of human endothelial cells during autophagy assessed in a biomimetic microfluidic device model.

AIMS: Autophagy is critical to endothelial function. We explored the effects of autophagy induced by serum deprivation on Human Umbilical Vascular Endothelial Cells (HUVEC) metabolome profile and its inhibition by the antimalarial drug chloroquine (CLQ) using a microfluidic biomimetic model. MAIN METHODS: The metabolites secreted by HUVEC into the circulating microfluidics were determined by liquid chromatography mass spectrometry (LC-MS) and further analyzed using Metaboanalyst 3.0 multivariate and pathway analysis tools. KEY FINDINGS: Principal component analysis showed the discrimination of metabolites between treated and control groups. The results also identified alterations in metabolites relevant to endothelial function such as arginine, glutamate and energy metabolism pathways. Interestingly, CLQ mostly reversed the changes induced by serum deprivation. SIGNIFICANCE: The knowledge of endothelial metabolic profile during autophagy may contribute to the identification of clinical biomarkers and potential therapeutic approaches based on the regulation of autophagy.

Capillary electrophoresis coupled to contactless conductivity detection for analysis of amino acids of agricultural interest in composting.

Composting is a sustainable approach to manage animal and vegetal waste generated in the Fundação Parque Zoológico de São Paulo. The resulting compost is often used in ZOO's premises as an organic fertilizer for the production of vegetables, which is further used to feed the animals. The composting product provides many forms of mineral and also amino acids (AA) that are absorbed by plants as nutrients. Since most amino acids absorb only slightly or not at all in the UV wavelengths, we developed a method for the determination of AA of agricultural interest in the composting samples. Due to the complexity of samples, we used ion exchange chromatography for the purification of AA prior to analysis. The proposed CZE-C4 D method allowed a separation of the AA in a short analysis time (less than 3.0 min), with great linearity (with R2 ranging from 0.993 to 0.998). Using a BGE of 10 mmol/L TEA, reduction of high-frequency noise and lower baseline fluctuations were obtained. The LOQ for the five AA were around 35 µmol/L, and were adequate for our purpose. In addition, the method showed good precision (RSD of peak area and migration time less than 1.55 and 1.16%, respectively).

Avaliação preliminar da associação entre anfotericina e hesperina com oxidantes e células huvec / Preliminary assessment of the association between amphotericin and hesperetin with oxididants and huvec cells

A anfotericina B (AmB) é fármaco o “padrão ouro” para o tratamento de infecções fúngicas invasivas desde 1960, Entretanto, a anfotericina B apresenta elevada toxicidade, a qual manifesta-se mais frequentemente nos rins e no fígado, Sabe-se, desde 1985, que a auto-oxidação da AmB origina diferentes formas de espécies reativas oxidativas e estas, por serem tóxicas para a célula, seriam responsáveis, em parte, pela toxicidade, Diferentes estudos indicam que a hesperidina contribui por meio do decréscimo do estresse oxidativo, para a proteção renal e contra a injúria gerada pela isquemia, Tal fato e o envolvimento da AmB na geração de radicais livres tornam interessante a avaliação preliminar do efeito da hesperidina e AmB (isoladamente ou associadas) frente a espécies reativas do oxigênio e radicais livres, bem como o estudo das mesmas em modelos de citoxicidade, Frente ao ABTS•+, a AmB apresentou IC50 igual a 0,0124mg/mL, mas quando associada à hesperidina este valor caiu para 0,0003mg/mL, Frente ao HOCl, a Amb apresentou IC50 igual a 0,0056, mas quando associada à hesperidina este valor caiu para 0,0023mg/mL, No ensaio com DPPH• e radical ânion superóxido as amostras não foram efetivas, No ensaio com células endoteliais em cultivo (HUVEC), as associações reduziram a viabilidade celular, Estes resultados preliminares evidenciam a interação dos compostos com espécies reativas bem como indicam possibilidade de exacerbação do dano pela AmB na presença dos antioxidantes em um modelo in vitro...

Amphotericin B (AmB) is drug “gold standard” for the treatment of invasive fungal infections since 1960. However, amphotericin B has high toxicity, which manifests itself most often in the kidneys and in the liver. It is known, since 1985, that self-oxidation of AmB gives different forms of reactive oxidative species and these, being toxic to the cell, would be responsible, in part, by its toxicity. Different studies indicate that hesperidin contributes, through the reduction of oxidative stress, to protect against renal injury generated by ischemia. This fact and the involvement of AmB in the generation of free radicals make it interesting the preliminary evaluation of the effect of hesperidin and AmB (alone or associated) against reactive oxygen species and free radicals, as well as the study on models of cytotoxicity. Front ABTS•+, AmB presented IC50 equal to 0.0124 mg/mL, but when it was associated to hesperidin this value has decreased to 0.0003 mg/mL. Front HOCl, Amb presented IC50 equal to 0.0056, but when it was associated to hesperidin this value has decreased to 0.0023 mg/mL. In the trials with DPPH• and the superoxide anion radical samples were not effective. In the assay with endotelial cell culture (HUVEC cells), the association has decreased cell viability. These preliminary results demonstrate the interaction of the compounds with reactive species as well as indicate the possibility of damage exacerbation by AmB in the presence of antioxidants in an in vitro model...

Recombinant hepatitis C virus-envelope protein 2 interactions with low-density lipoprotein/CD81 receptors

Hepatitis C virus (HCV) envelope protein 2 (E2) is involved in viral binding to host cells. The aim of this work was to produce recombinant E2B and E2Y HCV proteins in Escherichia coli and Pichia pastoris, respectively, and to study their interactions with low-density lipoprotein receptor (LDLr) and CD81 in human umbilical vein endothelial cells (HUVEC) and the ECV304 bladder carcinoma cell line. To investigate the effects of human LDL and differences in protein structure (glycosylated or not) on binding efficiency, the recombinant proteins were either associated or not associated with lipoproteins before being assayed. The immunoreactivity of the recombinant proteins was analysed using pooled serum samples that were either positive or negative for hepatitis C. The cells were immunophenotyped by LDLr and CD81 using flow cytometry. Binding and binding inhibition assays were performed in the presence of LDL, foetal bovine serum (FCS) and specific antibodies. The results revealed that binding was reduced in the absence of FCS, but that the addition of human LDL rescued and increased binding capacity. In HUVEC cells, the use of antibodies to block LDLr led to a significant reduction in the binding of E2B and E2Y. CD81 antibodies did not affect E2B and E2Y binding. In ECV304 cells, blocking LDLr and CD81 produced similar effects, but they were not as marked as those that were observed in HUVEC cells. In conclusion, recombinant HCV E2 is dependent on LDL for its ability to bind to LDLr in HUVEC and ECV304 cells. These findings are relevant because E2 acts to anchor HCV to host cells; therefore, high blood levels of LDL could enhance viral infectivity in chronic hepatitis C patients.

Recombinant hepatitis C virus-envelope protein 2 interactions with low-density lipoprotein/CD81 receptors.

Hepatitis C virus (HCV) envelope protein 2 (E2) is involved in viral binding to host cells. The aim of this work was to produce recombinant E2B and E2Y HCV proteins in Escherichia coli and Pichia pastoris, respectively, and to study their interactions with low-density lipoprotein receptor (LDLr) and CD81 in human umbilical vein endothelial cells (HUVEC) and the ECV304 bladder carcinoma cell line. To investigate the effects of human LDL and differences in protein structure (glycosylated or not) on binding efficiency, the recombinant proteins were either associated or not associated with lipoproteins before being assayed. The immunoreactivity of the recombinant proteins was analysed using pooled serum samples that were either positive or negative for hepatitis C. The cells were immunophenotyped by LDLr and CD81 using flow cytometry. Binding and binding inhibition assays were performed in the presence of LDL, foetal bovine serum (FCS) and specific antibodies. The results revealed that binding was reduced in the absence of FCS, but that the addition of human LDL rescued and increased binding capacity. In HUVEC cells, the use of antibodies to block LDLr led to a significant reduction in the binding of E2B and E2Y. CD81 antibodies did not affect E2B and E2Y binding. In ECV304 cells, blocking LDLr and CD81 produced similar effects, but they were not as marked as those that were observed in HUVEC cells. In conclusion, recombinant HCV E2 is dependent on LDL for its ability to bind to LDLr in HUVEC and ECV304 cells. These findings are relevant because E2 acts to anchor HCV to host cells; therefore, high blood levels of LDL could enhance viral infectivity in chronic hepatitis C patients.

Inflammatory response of endothelial cells to hepatitis C virus recombinant envelope glycoprotein 2 protein exposure.

The hepatitis C virus (HCV) encodes approximately 10 different structural and non-structural proteins, including the envelope glycoprotein 2 (E2). HCV proteins, especially the envelope proteins, bind to cell receptors and can damage tissues. Endothelial inflammation is the most important determinant of fibrosis progression and, consequently, cirrhosis. The aim of this study was to evaluate and compare the inflammatory response of endothelial cells to two recombinant forms of the HCV E2 protein produced in different expression systems (Escherichia coli and Pichia pastoris). We observed the induction of cell death and the production of nitric oxide, hydrogen peroxide, interleukin-8 and vascular endothelial growth factor A in human umbilical vein endothelial cells (HUVECs) stimulated by the two recombinant E2 proteins. The E2-induced apoptosis of HUVECs was confirmed using the molecular marker PARP. The apoptosis rescue observed when the antioxidant N-acetylcysteine was used suggests that reactive oxygen species are involved in E2-induced apoptosis. We propose that these proteins are involved in the chronic inflammation caused by HCV.

Inflammatory response of endothelial cells to hepatitis C virus recombinant envelope glycoprotein 2 protein exposure

The hepatitis C virus (HCV) encodes approximately 10 different structural and non-structural proteins, including the envelope glycoprotein 2 (E2). HCV proteins, especially the envelope proteins, bind to cell receptors and can damage tissues. Endothelial inflammation is the most important determinant of fibrosis progression and, consequently, cirrhosis. The aim of this study was to evaluate and compare the inflammatory response of endothelial cells to two recombinant forms of the HCV E2 protein produced in different expression systems (Escherichia coli and Pichia pastoris). We observed the induction of cell death and the production of nitric oxide, hydrogen peroxide, interleukin-8 and vascular endothelial growth factor A in human umbilical vein endothelial cells (HUVECs) stimulated by the two recombinant E2 proteins. The E2-induced apoptosis of HUVECs was confirmed using the molecular marker PARP. The apoptosis rescue observed when the antioxidant N-acetylcysteine was used suggests that reactive oxygen species are involved in E2-induced apoptosis. We propose that these proteins are involved in the chronic inflammation caused by HCV.

Influence of FcγRIIIb polymorphism on its ability to cooperate with FcγRIIa and CR3 in mediating the oxidative burst of human neutrophils.

Considering that human neutrophil FcγRIIa and FcγRIIIb receptors interact synergistically with CR3 in triggering neutrophil functional responses, allelic polymorphisms in these receptors might influence such interactions. We assessed whether FcγRIIIb polymorphisms affect FcγR/CR cooperation in mediating the neutrophil oxidative burst (OB), in particular the FcγRIIIb/CR3 cooperation that occurs via lectin-saccharide-like interactions. The OB of human neutrophil antigen (HNA)-1a-, HNA-1b-, and HNA-1a/-1b-neutrophils stimulated with immune complexes, opsonized or not with serum complement, was measured by the luminol-enhanced chemiluminescence assay. Compared with HNA-1a-neutrophils, HNA-1b-neutrophils exhibited reduced FcγR-stimulated OB, but increased FcγR/CR-stimulated OB. It suggests that (i) FcγR and CR cooperate more effectively in HNA-1b-neutrophils, and (ii) the HNA-1b allotype influences the FcγRIIIb cooperation with FcγRIIa, but not with CR3. HNA-1a- and HNA-1b-neutrophils exhibited similar OB responses elicited via CR3 alone or via FcγR/CR-independent pathways. In addition, the level of FcγRIIIb, FcγRIIa, and CR3 expression did not differ significantly among the neutrophil groups studied. Together, these results demonstrate that the HNA-1b allotype influences the functional cooperation between FcγRIIIb and FcγRIIa, and suggest that the difference in the glycosylation pattern between HNA-1a and HNA-1b does not affect the FcγRIIIb cooperation with CR3.

Development of diagnostic methods and study of the immunoreactivity of a mixture of recombinant core and E2 proteins fused to GST with control serum positive for hepatitis C.

The hepatitis C virus (HCV) is an enveloped virus that is about 50-70 nm in diameter, has positive-strand RNA, and belongs to the genus Hepacivirus and the family Flaviridae. The detection and quantification of the core antigen, HCV nucleocapsid protein, has been successful in many trials and is considered a marker of viral replication since it presents a sequence of highly conserved amino acids, giving it high sensitivity and specificity. The E2 protein is an envelope glycoprotein of HCV with 11 glycosylation sites; most of these are well-conserved, making it a target antigen. The aim of this study is to develop high-sensitivity, low-cost diagnostic methods for HCV, which could be used for serological screening. The genomic regions encoding the core (part 136 aa) and E2 proteins of HCV were expressed in Escherichia coli Rosetta strain, cloned in expression vector pET-42a, and induced with 0.4 m mol L(-1) IPTG, producing recombinant proteins that were fused to glutathione S-transferase (GST) protein, which was then purified by affinity chromatography. The immunoreactivity was assessed by Western blot, Slot Blot, and developed and improved diagnostic methods (capture, indirect, and immunoblotting enzyme-linked immunosorbent assay (ELISA)). After applying the results to the formulas for determining the quality parameters, obtained for immunoblotting method 100% sensitivity and specificity and for ELISA 100% sensitivity and 87.5% specificity. The methods developed were more sensitive and specific using the mixture of the recombinant proteins fused to GST (core+E2).

Evaluation of the lipid profile between individuals with hepatitis C

Metabolic profiles correlate with hepatitis C virus (HCV) infection and are prognostic for the viral response. However, little is known about the association between lipid profiles and viral load in chronic patients carrying HCV genotypes 1, 2 and 3. The aim of this study was to investigate the influence of the viremia and viral genotype on lipid metabolism by observing the variations in serum lipoprotein and apolipoprotein B, to assess whether HCV predisposes individuals to lipid imbalance and favors the appearance of vascular complications. A sample group of 150 chronic HCV patients with viral genotypes 1, 2 or 3 and a control group of 20 healthy adults (10 men and 10 women), all aged from 20 to 50 years were studied. The serum lipid profile of the chronic patients was analyzed and compared to that of the control group. The high-density lipoprotein (HDL), very low-density lipoprotein (VLDL) and triglyceride levels of the sample group were lower than those of the control group, while the low-density lipoprotein (LDL) and apolipoprotein B levels of the patients were higher. These differences were more significant in patients carrying genotype 3a. There was a positive correlation between the viremia and the changes in apolipoprotein B levels in patients carrying genotype 1b. It was inferred that the risk of developing vascular complications raised in HCV patients. As 90% of LDL protein is composed of apolipoprotein B, the plasmatic concentration of the latter indicates the number of potentially atherogenic particles. Therefore, the lipid profile monitoring may aid in the diagnosis of hepatic infection severity and equally act as a good prognostic marker.

Perfis metabólicos correlacionam-se com infecção pelo vírus da hepatite C (VHC) e são prognósticos da resposta viral em pacientes crônicos. Porém, pouco se sabe a respeito da associação entre perfis lipídicos e a carga viral entre infecções dos genótipos 1, 2 e 3. O objetivo foi estudar a influência da viremia e dos genótipos virais sobre o metabolismo lipídico através das variações de lipoproteínas séricas e apolipoproteína B em hepatopatas crônicos, avaliando se o vírus predispõe os indivíduos a complicações vasculares. O grupo amostral constituiu-se de 150 pacientes crônicos e grupo controle de 20 indivíduos saudáveis. Níveis séricos de HDL, VLDL e triglicérides mostraram-se diminuídos em relação ao grupo controle, enquanto os níveis de LDL e apolipoproteína B mostraram-se elevados. Observou-se correlação positiva entre a viremia e alterações de LDL e apolipoproteína B nos portadores do genótipo 1b. Assim, foi pressuposto que o risco de pacientes portadores do VHC desenvolverem complicações vasculares é elevado, uma vez que cerca de 90% da proteína na LDL constitui-se de apolipoproteína B, sua concentração plasmática indica o número de partículas aterogênicas. Portanto, o monitoramento do perfil lipídico pode auxiliar no diagnóstico da severidade da infecção hepática causada pelo VHC e atuar como bom sinal prognóstico.