Epicardial slices: an innovative 3D organotypic model to study epicardial cell physiology and activation.

The epicardium constitutes an untapped reservoir for cardiac regeneration. Upon heart injury, the adult epicardium re-activates, leading to epithelial-to-mesenchymal transition (EMT), migration, and differentiation. While interesting mechanistic and therapeutic findings arose from lower vertebrates and rodent models, the introduction of an experimental system representative of large mammals would undoubtedly facilitate translational advancements. Here, we apply innovative protocols to obtain living 3D organotypic epicardial slices from porcine hearts, encompassing the epicardial/myocardial interface. In culture, our slices preserve the in vivo architecture and functionality, presenting a continuous epicardium overlaying a healthy and connected myocardium. Upon thymosin ß4 treatment of the slices, the epicardial cells become activated, upregulating epicardial and EMT genes, resulting in epicardial cell mobilization and differentiation into epicardial-derived mesenchymal cells. Our 3D organotypic model enables to investigate the reparative potential of the adult epicardium, offering an advanced tool to explore ex vivo the complex 3D interactions occurring within the native heart environment.

Biodegradable silicon nanoneedles delivering nucleic acids intracellularly induce localized in vivo neovascularization.

The controlled delivery of nucleic acids to selected tissues remains an inefficient process mired by low transfection efficacy, poor scalability because of varying efficiency with cell type and location, and questionable safety as a result of toxicity issues arising from the typical materials and procedures employed. High efficiency and minimal toxicity in vitro has been shown for intracellular delivery of nuclei acids by using nanoneedles, yet extending these characteristics to in vivo delivery has been difficult, as current interfacing strategies rely on complex equipment or active cell internalization through prolonged interfacing. Here, we show that a tunable array of biodegradable nanoneedles fabricated by metal-assisted chemical etching of silicon can access the cytosol to co-deliver DNA and siRNA with an efficiency greater than 90%, and that in vivo the nanoneedles transfect the VEGF-165 gene, inducing sustained neovascularization and a localized sixfold increase in blood perfusion in a target region of the muscle.

Effect of calcium addition and pH on yield and texture of Minas cured cheese / Efeito da adição de cálcio e do pH sobre o rendimento e a textura de queijo-de-Minas curado

Milk calcium concentration is a factor related to cheese texture, an important rheological property of cheese quality as perceived by consumers. This study aimed to evaluate the effect of different pH conditions (5.8 and 6.6) and calcium addition (0, 150, 300 ppm of CaCl2), on yield and nutrient retention of the clots obtained and on the texture of Minascured cheese. Clots were analyzed for wet and dry yield, percentage content and retention of protein, fat and calcium. The texture of the cheese was evaluated by instrumental and sensorial tests. No differences were observed on the wet and dry yields, or on the protein content, fat and calcium retention of clots produced in the different experimental conditions. The instrumental evaluation showed that calcium addition significantly influenced the texture of cheeses, regardless of the pH of milk clotting. The sensory panel did not find a difference in the hardness ofcheeses produced at the same pH of milk clotting in function of CaCl2 addition. There was no difference in the texture of Minascured cheese due to the calcium addition to milk for dairy product consumers, which brings a new perspective on manufacture for cheese markers.

Avaliou-se o efeito de diferentes condições de pH ­5,8 e 6,6 ­e da adição de cálcio ­0, 150, 300ppm de CaCl2 - sobre o rendimento, a retenção de nutrientes nos coágulos produzidos e a textura de queijo-de-Minas curado. Foram analisados nos coágulos os rendimentos úmido e seco, o percentual e a retenção de proteína, de gordura e de cálcio. A textura dos queijos foi avaliada por testes instrumental e sensorial. Não foram observadas diferenças nos rendimentos úmido e seco, no conteúdo percentual e na retenção de proteína, gordura e cálcio nos coágulos produzidos em diferentes condições experimentais. A análise instrumental mostrou que a adição ou não de cálcio influenciou a textura dos queijos, independentemente do pH de coagulação do leite. O painel sensorial não diferiu quanto à dureza dos queijos produzidos em um mesmo valor de pH de coagulação do leite mediante a adição de CaCl2. Para os consumidores, não houve diferença na textura do queijo Minas curado em razão da adição de cálcio ao leite. Isto traz nova perspectiva na fabricação para os produtores de queijo.

In vivo evaluation of safety of nanoporous silicon carriers following single and multiple dose intravenous administrations in mice.

Porous silicon (pSi) is being extensively studied as an emerging material for use in biomedical applications, including drug delivery, based on the biodegradability and versatile chemical and biophysical properties. We have recently introduced multistage nanoporous silicon microparticles (S1MP) designed as a cargo for nanocarrier drug delivery to enable the loaded therapeutics and diagnostics to sequentially overcome the biological barriers in order to reach their target. In this first report on biocompatibility of intravenously administered pSi structures, we examined the tolerability of negatively (-32.5±3.1mV) and positively (8.7±2.5mV) charged S1MP in acute single dose (10(7), 10(8), 5×10(8) S1MP/animal) and subchronic multiple dose (10(8) S1MP/animal/week for 4 weeks) administration schedules. Our data demonstrate that S1MP did not change plasma levels of renal (BUN and creatinine) and hepatic (LDH) biomarkers as well as 23 plasma cytokines. LDH plasma levels of 145.2±23.6, 115.4±29.1 vs. 127.0±10.4; and 155.8±38.4, 135.5±52.3 vs. 178.4±74.6 were detected in mice treated with 10(8) negatively charged S1MP, 10(8) positively charged S1MP vs. saline control in single and multiple dose schedules, respectively. The S1MPs did not alter LDH levels in liver and spleen, nor lead to infiltration of leukocytes into the liver, spleen, kidney, lung, brain, heart, and thyroid. Collectively, these data provide evidence of a safe intravenous administration of S1MPs as a drug delivery carrier.

Size and shape effects in the biodistribution of intravascularly injected particles.

Understanding how size and shape can affect the biodistribution of intravascularly injected particles is of fundamental importance both for the rational design of delivery systems and from a standardization and regulatory view point. In this work, uncoated silica spherical beads, with a diameter ranging from 700 nm to 3 microm, and uncoated non-spherical silicon-based particles, with quasi-hemispherical, cylindrical and discoidal shapes, have been injected into tumor bearing mice. The number of particles accumulating in the major organs and within the tumor mass has been measured through elemental silicon (Si) analysis. For the spherical beads, it has been found that the number of particles accumulating in the non-RES organs reduces monotonically as the diameter d increases, suggesting the use of smaller particles to provide a more uniform tissue distribution. However, discoidal particles have been observed to accumulate more than others in most of the organs but the liver, where cylindrical particles are deposited at a larger extent. These preliminary results support the notion of using sub-micrometer discoidal particles as intravascular carriers to maximize accumulation in the target organ whilst reducing sequestration by the liver.

The effect of shape on the margination dynamics of non-neutrally buoyant particles in two-dimensional shear flows.

The margination dynamics of microparticles with different shapes has been analyzed within a laminar flow mimicking the hydrodynamic conditions in the microcirculation. Silica spherical particles, quasi-hemispherical and discoidal silicon particles have been perfused in a parallel plate flow chamber. The effect of the shape and density on their margination propensity has been investigated at different physiologically relevant shear rates S. Simple scaling laws have been derived showing that the number n of marginating particles scales as S(-0.63) for the spheres; S(-0.85) for discoidal and S(-1) for quasi-hemispherical particles, regardless of their density and size. Within the range considered for the shear rate, discoidal particles marginate in a larger number compared to quasi-hemispherical and spherical particles. These results may be of interest in drug delivery and bio-imaging applications, where particles are expected to drift towards and interact with the walls of the blood vessels.

Supersonic cluster beam deposition of nanostructured thin films with uniform thickness via continuously graded exposure control.

Supersonic cluster beam deposition is a powerful technique for the production of nanostructured thin films and the microfabrication with stencil masks of patterns with very good lateral resolution. The high focusing of cluster beam typical of supersonic expansions causes the deposition of films with strong thickness variation over a small area. To overcome this problem we have designed and tested a rotating screen allowing a continuously graded exposure of the substrate during cluster beam deposition. This allows the production of nanostructured films with uniform thickness over a large area while keeping all the features typical of supersonic beams.