Vascular Tissue Engineering: Polymers and Methodologies for Small Caliber Vascular Grafts.

Cardiovascular disease is the most common cause of death in the world. In severe cases, replacement or revascularization using vascular grafts are the treatment options. While several synthetic vascular grafts are clinically used with common approval for medium to large-caliber vessels, autologous vascular grafts are the only options clinically approved for small-caliber revascularizations. Autologous grafts have, however, some limitations in quantity and quality, and cause an invasiveness to patients when harvested. Therefore, the development of small-caliber synthetic vascular grafts (<5 mm) has been urged. Since small-caliber synthetic grafts made from the same materials as middle and large-caliber grafts have poor patency rates due to thrombus formation and intimal hyperplasia within the graft, newly innovative methodologies with vascular tissue engineering such as electrospinning, decellularization, lyophilization, and 3D printing, and novel polymers have been developed. This review article represents topics on the methodologies used in the development of scaffold-based vascular grafts and the polymers used in vitro and in vivo.

Update on the main use of biomaterials and techniques associated with tissue engineering.

Regenerative medicine involves the study of cells, signaling cues and biomatrices to restore normal function of tissues and organs. To develop the matrices for use in tissue engineering there are three main groups of biomaterials: (i) naturally derived materials; (ii) synthetic polymers; and (iii) decellularized organ or tissue scaffolds. These biomaterials, in various forms such as hydrogels, nanofibers and 3D scaffolds, among others, have been employed for different tissue regeneration purposes, with several techniques involved in their production, including rapid prototyping, tissue decellularization and electrospinning. In this review, the main topics of hydrogels, 3D printing and electrospun scaffolds, other biomaterials and decellularization and recellularization will be discussed.

Evaluation of semi-automated cells counting in peritoneal fluid / Avaliação de semiautomação para contagem de células em líquido peritoneal

ABSTRACTIntroduction:Currently, the cytological analysis of biological fluids, such as peritoneal fluid, is performed by manually cells counting in Fuchs-Rosenthal chamber. However, this method has a number of limitations. Because of these limitations, automatic counters have been evaluated for cell counting in this type of sample in order to make it faster and more reliable test.Objective:The aim of this study is to compare the manual and semi-automated leukocytes and erythrocytes counting in peritoneal fluid.Materials and methods:The samples were analyzed manually and using the CountessTM(Invitrogen).Results:The results showed that although there is a correlation between the two counting methods, the correlation is relatively low, for both leukocytes and erythrocytes analysis.Conclusion:The results suggest that peritoneal fluid should continue to be analyzed in Fuchs-Rosenthal chamber. However, further studies should be conducted with a greater number of samples to investigate the possibility of using automated cells counting in serous fluids and, thus, provide greater speed and quality of results.

RESUMOIntrodução:Atualmente, a análise citológica de líquidos biológicos, como líquido peritoneal, é realizada por meio da contagem manual de células, em câmara de Fuchs-Rosenthal. Porém, esse método apresenta uma série de limitações. Com isso, contadores automáticos têm sido avaliados para a contagem de células nesse tipo de amostra a fim de tornar esse exame mais rápido e confiável.Objetivo:Comparar a contagem manual e semiautomatizada de leucócitos e eritrócitos em líquido peritoneal.Materiais e métodos:As amostras foram analisadas manualmente e no contador de células CountessTM (Invitrogen).Resultados:Os resultados mostraram que apesar de existir correlação entre os dois métodos de contagem, essa correlação é relativamente fraca, tanto para análise de leucócitos como para de eritrócitos.Conclusão:Esses resultados sugerem que o líquido peritoneal deve continuar a ser analisado em câmara de Fuchs-Rosenthal, contudo novos estudos devem ser realizados, com maior número de amostras, para investigar a possibilidade do uso de automação na contagem de células em líquidos serosos e, assim, proporcionar maior agilidade e qualidade no resultado.

Mesenchymal stem cells and nanofibers as scaffolds for the regeneration of thyroid cartilage.

OBJECTIVES/HYPOTHESIS: The aim of this study has been to establish an alternative approach in the form of regeneration of the thyroid cartilage. STUDY DESIGN: Four 1-month old pigs (Sus scrofa) were used (divided into 3 groups) and submitted to general anesthetic to perform cervictomy with exposure of the thyroid cartilage in a total of 12 (twelve) samples. METHOD: A resection of 4.0 cm(2) of cartilage was carried out in the right upper region and in the left upper and lower left region of the cartilage, where a scaffold with or without stem cells was implanted. In the left lower region, no biomaterial was implanted and the defect was left open (lesion control [L]). RESULTS: The average extension of the cartilaginous neoformation of L group was 136.3 µm (± 9.6) and 387.7 µm (± 43.2) in the scaffold (SCA) group, presenting a significant statistical difference (P < 0.01). The analysis carried out on the lesion site sections of the cartilage of the larynx of the animals from the SCA group + mesenchymal stem cells (SCA+MSC) showed an average of the extension of neocartilage of 825.4 µm (± 122.1), showing a more extensive area of neocartilage when compared to the other groups. These results demonstrated a high significantly statistical difference (P < 0.001) when compared with the L and SCA groups. CONCLUSION: In 100% of the cases for which SCA+MSCs were used, a significant success in the cartilage growth and closing of the lesion in the thyroid cartilage was obtained compared to the other two groups for which MSCs were not used. LEVEL OF EVIDENCE: N/A.

Electrospinning for regenerative medicine: a review of the main topics.

Electrospun fibers are promising tissue engineering scaffolds that offer the cells an environment that mimics the native extracellular matrix. Fibers with different characteristics can be produced by the electrospinning technique according to the needs of the tissue to be repaired. In this review, the process of electrospinning was examined, providing a description of the common techniques used for the physicochemical and biological characterization of electrospun fibers. The review also discusses the potential applications of electrospun scaffolds for tissue engineering, based on scientific literature.