Assessment of the Biocompatibility of the PLLA-PLCL Scaffold Obtained by Electrospinning

AbstractElectrospun membranes of poly (L-Lactide) / poly (L-lactide-co-caprolactone) blend were produced and evaluated by physical and mechanical tests to use as a scaffold for cell growth. The membranes were seeded with endothelial cells (HUVEC) and after culturing time it was visualized by confocal laser scanning microscopy and scanning electron microscopy. The results indicate that the process parameters were capable of producing PLLA-PLCL membranes presenting fibers with diameters in the nanometer range. The scaffolds supported cell attachment and growth, indicating the feasibility of producing scaffolds by electrospinning technique, which could be used in tissue engineering applications

Conditioning of hiPSC-derived cardiomyocytes using surface topography obtained with high throughput technology

Surface functionalization of polymers aims to introduce novel properties that favor bioactive responses. We have investigated the possibility of surface functionalization of polyethylene terephthalate (PET) sheets by the combination of laser ablation with hot embossing and the application of such techniques in the field of stem cell research. We investigated the response of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to topography in the low micrometer range. HiPSC-CMs are expected to offer new therapeutic tools for myocardial replacement or regeneration after an infarct or other causes of cardiac tissue loss. However, hiPSC-CMs are phenotypically immature compared to myocytes in the adult myocardium, hampering their clinical application. We aimed to develop and test a high-throughput technique for surface structuring that would improve hiPSC-CMs structural maturation. We used laser ablation with a ps-laser source in combination with nanoimprint lithography to fabricate large areas of homogeneous micron- to submicron line-like pattern with a spatial period of 3 µm on the PET surface. We evaluated cell morphology, alignment, sarcomeric myofibrils assembly, and calcium transients to evaluate phenotypic changes associated with culturing hiPSC-CMs on functionalized PET. Surface functionalization through hot embossing was able to generate, at low cost, low micrometer features on the PET surface that influenced the hiPSC-CMs phenotype, suggesting improved structural and functional maturation. This technique may be relevant for high-throughput technologies that require conditioning of hiPSC-CMs and may be useful for the production of these cells for drug screening and disease modeling applications with lower costs.Fil: Cortella, Lucas R. X.. Universidade de Sao Paulo; BrasilFil: Cestari, Idágene A.. Universidade de Sao Paulo; BrasilFil: Lahuerta, Ricardo D.. Universidade de Sao Paulo; BrasilFil: Arana, Matheus C.. Universidade de Sao Paulo; BrasilFil: Soldera, Marcos Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; ArgentinaFil: Rank, Andreas. Technische Universität Dresden; AlemaniaFil: Lasagni, Andrés F.. Technische Universität Dresden; AlemaniaFil: Cestari, Ismar N.. Universidade de Sao Paulo; Brasi

Hemodynamic performance and inflammatory response during the use of VAD-InCor as a bridge to transplant

FUNDAMENTO: O transplante cardíaco enfrenta o grave problema da escassez de doadores. Estima-se que entre 20% e 40% dos pacientes falecem na fila de espera. Para esses pacientes, a utilização de dispositivos de assistência circulatória é, muitas vezes, a única possibilidade de sobrevivência durante a espera do doador. No Brasil, não existe nenhum programa regular de utilização desses dispositivos como ponte para transplante. OBJETIVO: Avaliar o desempenho hemodinâmico e a resposta inflamatória durante a utilização do DAV-InCor como ponte para transplante. MÉTODOS: Entre outubro de 2003 e abril de 2006, 11 pacientes, indicados em caráter de prioridade para o transplante cardíaco, evoluíram em choque cardiogênico refratário. O implante do DAV-InCor foi realizado em sete pacientes. O diagnóstico etiológico foi cardiopatia chagásica em cinco pacientes e cardiomiopatia dilatada idiopática em dois. RESULTADOS: A assistência mecânica ao ventrículo esquerdo foi mantida nos sete pacientes por períodos entre 14 e 42 dias (média 26,2). O desempenho hemodinâmico foi adequado, com a normalização do índice cardíaco, dos níveis de saturação venosa de O2 e do lactato. O transplante foi realizado em dois pacientes, os outros cinco faleceram por infecção sistêmica ou falência de múltiplos órgãos. CONCLUSÃO: O desempenho do DAV-Incor, no comportamento hemodinâmico dos pacientes estudados, foi adequado para a manutenção de uma condição circulatória satisfatória durante o período estudado. Houve melhora dos parâmetros de perfusão tecidual e manutenção de sinais de resposta inflamatória sistêmica. Houve alta incidência de complicações; contudo, não foram demonstradas complicações relacionadas ao dispositivo que comprometam a segurança da utilização do mesmo.BACKGROUND: Cardiac transplantation faces the serious problem of lack of donors and it is estimated that 20 to 40% of the patients die while waiting for heart transplantation. For these patients, the use of mechanical circulatory assist devices is the only choice of survival while waiting for a donor. In Brazil, the experience with mechanical circulatory support is limited and there is no regular program regarding the use of these devices as a bridge to heart transplantation. OBJECTIVE: To evaluate the hemodynamic performance and the systemic inflammatory response during the clinical use of the InCor-type ventricular assist device (VAD-InCor) as a bridge to heart transplantation. METHODS: Between October 2003 and April 2006, 11 patients in the waiting list for heart transplantation presented hemodynamic deterioration due to refractory cardiogenic shock. Seven of these patients were submitted to VAD-InCor implantation for left ventricular assistance. The etiologic diagnosis was Chagas' disease in 5 patients and idiopathic dilated cardiomyopathy in 2. RESULTS: The duration of left ventricular assistance ranged from 14 to 42 days (mean 26.2 days). During this period, the hemodynamic performance of the DAV-InCor was adequate to support a normal hemodynamic state. There was normalization of central venous oxygen saturation and serum lactate. Two patients were submitted to heart transplantation, while the other 5 patients died under assistance due to infection and multiple organ failure. CONCLUSION: The performance of the VAD-InCor, in the hemodynamic behavior of the studied patients, was adequate for the maintenance of a satisfactory circulatory state during the studied period. There was improvement in the tissue perfusion parameters and maintenance of systemic inflammatory response signs. There was a high incidence of complications; however, complications related to the device, which could compromise the safety of its use, were not demonstrated.FAPESPCNP

A new approach to heart valve tissue engineering:mimicking the heart ventricle with a ventricular assist device in a novel bioreactor.

The `biomimetic` approach to tissue engineering usually involves the use of a bioreactor mimicking physiological parameters whilst supplying nutrients to the developing tissue. Here we present a new heart valve bioreactor, having as its centrepiece a ventricular assist device (VAD), which exposes the cell-scaffold constructs to a wider array of mechanical forces. The pump of the VAD has two chambers: a blood and a pneumatic chamber, separated by an elastic membrane. Pulsatile air-pressure is generated by a piston-type actuator and delivered to the pneumatic chamber, ejecting the fluid in the blood chamber. Subsequently, applied vacuum to the pneumatic chamber causes the blood chamber to fill. A mechanical heart valve was placed in the VAD`s inflow position. The tissue engineered (TE) valve was placed in the outflow position. The VAD was coupled in series with a Windkessel compliance chamber, variable throttle and reservoir, connected by silicone tubings. The reservoir sat on an elevated platform, allowing adjustment of ventricular preload between 0 and 11 mmHg. To allow for sterile gaseous exchange between the circuit interior and exterior, a 0.2 mu m filter was placed at the reservoir. Pressure and flow were registered downstream of the TE valve. The circuit was filled with culture medium and fitted in a standard 5% CO(2) incubator set at 37 degrees C. Pressure and flow waveforms were similar to those obtained under physiological conditions for the pulmonary circulation. The `cardiomimetic` approach presented here represents a new perspective to conventional biomimetic approaches in TE, with potential advantages. Copyright (C) 2010 John Wiley & Sons, Ltd.Norwegian State Educational Loan FundSkipsreder Tom Wilhelmsens StiftelseKrista and Viggo Petersens FondKnut Hamsuns MinnefondHotelejer Anders Mansson og hustru Hanne Manssons LegatOticon FondenReinholdt W. Jorck og Hustrus FondNorwegian Society of Graduate Technical and Scientific Professional

Early changes in myocyte contractility and cardiac function in streptozotocin-induced type 1 diabetes in rats.

Diabetes can elicit direct deleterious effects on the myocardium, independent of coronary artery disease or hypertension. These cardiac disturbances are termed diabetic cardiomyopathy showing increased risk of heart failure with or without reduced ejection fraction. Presently, there is no specific treatment for this type of cardiomyopathy and in the case of type I diabetes, it may start in early childhood independent of glycemic control. We hypothesized that alterations in isolated myocyte contractility and cardiac function are present in the early stages of experimental diabetes in rats before overt changes in myocardium structure occur. Diabetes was induced by single-dose injection of streptozotocin (STZ) in rats with data collected from control and diabetic animals 3 weeks after injection. Left ventricle myocyte contractility was measured by single-cell length variation under electrical stimulation. Cardiac function and morphology were studied by high-resolution echocardiography with pulsed-wave tissue Doppler imaging (TDI) measurements and three-lead surface electrocardiogram. Triglycerides, cholesterol and liver enzyme levels were measured from plasma samples obtained from both groups. Myocardial collagen content and perivascular fibrosis of atria and ventricle were studied by histological analysis after picrosirius red staining. Diabetes resulted in altered contractility of isolated cardiac myocytes with increased contraction and relaxation time intervals. Echocardiography showed left atrium dilation, increased end-diastolic LV and posterior wall thickness, with reduced longitudinal systolic peak velocity (S') of the septum mitral annulus at the apical four-chamber view obtained by TDI. Triglycerides, aspartate aminotransferase and alkaline phosphatase were elevated in diabetic animals. Intertitial collagen content was higher in atria of both groups and did not differ among control and diabetic animals. Perivascular intramyocardial arterioles collagen did not differ between groups. These results suggest that alterations in cardiac function are present in the early phase in this model of diabetes type 1 and occur before overt changes in myocardium structure appear as evaluated by intersticial collagen deposition and perivascular fibrosis of intramyocardial arterioles