Microvascular engineering: Dynamic changes in microgel-entrapped vascular cells correlates with higher vasculogenic/angiogenic potential.

Successful strategies to promote neovascularization of ischemic tissues are still scarce, being a central priority in regenerative medicine. Microparticles harboring primitive vascular beds are appealing cell delivery candidates for minimally-invasive therapeutic vascularization. However, dynamic cellular alterations associated with in vitro vascular morphogenesis are still elusive. Here, bioengineered microgels guided the assembly of entrapped outgrowth endothelial cells (OEC) and mesenchymal stem cells (MSC) into cohesive vascularized microtissues. During in vitro maturation, OEC formed capillary-like networks enveloped in newly-formed extracellular matrix. Gene expression profiling showed that OEC acquired a mesenchymal-like phenotype, suggesting the occurrence of partial endothelial-to-mesenchymal transition (EndMT), while MSC remained transcriptionally stable. The secretome of entrapped cells became more pro-angiogenic, with no significant alterations of the inflammatory profile. Importantly, matured microgels showed improved cell survival/retention after transplantation in mice, with preservation of capillary-like networks and de novo formation of human vascular structures. These findings support that in vitro priming and morphogenesis of vessel-forming cells improves their vasculogenic/angiogenic potential, which is of therapeutic relevance, shedding some light on the associated mechanisms.

Decellularized human colorectal cancer matrices polarize macrophages towards an anti-inflammatory phenotype promoting cancer cell invasion via CCL18.

Macrophages are frequently identified in solid tumors, playing important roles in cancer progression. Their remarkable plasticity makes them very sensitive to environmental factors, including the extracellular matrix (ECM). In the present work, we investigated the impact of human colorectal tumor matrices on macrophage polarization and on macrophage-mediated cancer cell invasion. Accordingly, we developed an innovative 3D-organotypic model, based on the decellularization of normal and tumor tissues derived from colorectal cancer patients' surgical resections. Extensive characterization of these scaffolds revealed that DNA and other cell constituents were efficiently removed, while native tissue characteristics, namely major ECM components, architecture and mechanical properties, were preserved. Notably, normal and tumor decellularized matrices distinctly promoted macrophage polarization, with macrophages in tumor matrices differentiating towards an anti-inflammatory M2-like phenotype (higher IL-10, TGF-ß and CCL18 and lower CCR7 and TNF expression). Matrigel invasion assays revealed that tumor ECM-educated macrophages efficiently stimulated cancer cell invasion through a mechanism involving CCL18. Notably, the high expression of this chemokine at the invasive front of human colorectal tumors correlated with advanced tumor staging. Our approach evidences that normal and tumor decellularized matrices constitute excellent scaffolds when trying to recreate complex microenvironments to understand basic mechanisms of disease or therapeutic resistance.

Three-dimensional scaffolds of fetal decellularized hearts exhibit enhanced potential to support cardiac cells in comparison to the adult.

A main challenge in cardiac tissue engineering is the limited data on microenvironmental cues that sustain survival, proliferation and functional proficiency of cardiac cells. The aim of our study was to evaluate the potential of fetal (E18) and adult myocardial extracellular matrix (ECM) to support cardiac cells. Acellular three-dimensional (3D) bioscaffolds were obtained by parallel decellularization of fetal- and adult-heart explants thereby ensuring reliable comparison. Acellular scaffolds retained main constituents of the cardiac ECM including distinctive biochemical and structural meshwork features of the native equivalents. In vitro, fetal and adult ECM-matrices supported 3D culture of heart-derived Sca-1(+) progenitors and of neonatal cardiomyocytes, which migrated toward the center of the scaffold and displayed elongated morphology and excellent viability. At the culture end-point, more Sca-1(+) cells and cardiomyocytes were found adhered and inside fetal bioscaffolds, compared to the adult. Higher repopulation yields of Sca-1(+) cells on fetal ECM relied on ß1-integrin independent mitogenic signals. Sca-1(+) cells on fetal bioscaffolds showed a gene expression profile that anticipates the synthesis of a permissive microenvironment for cardiomyogenesis. Our findings demonstrate the superior potential of the 3D fetal microenvironment to support and instruct cardiac cells. This knowledge should be integrated in the design of next-generation biomimetic materials for heart repair.

Arginine vasopressin regulates CFTR and ClC-2 mRNA expression in rat kidney cortex and medulla.

The presence of both CFTR and ClC-2 proteins in the kidney suggest that they are involved in chloride transport along the nephron but their physiological roles in this organ are not known. To further understand the role of these chloride channels we studied Wistar rats subjected to dehydration for 2 days and also the homozygous Brattleboro rats, a strain of Long-Evans rats carrying an autosomal recessive mutation that leads to a deficiency of arginine-vasopressin (AVP) secretion in the plasma. The expression of CFTR was increased in the medulla of dehydrated Wistar rats and no variation was observed in the cortex. The expression of both ClC-2 and CFTR mRNAs was low in the renal cortex and medulla of the homozygous Brattleboro rats but returned to normal levels after AVP reposition. By the use of Madine-Darby canine kidney (MDCK) type I epithelial cells, it was observed that AVP (10(-8), 10(-7) and 10(-6) M) increased CFTR mRNA expression "in vitro" but no effect was observed when changes in the medium tonicity were caused by the addition of sucrose, NaCl, manitol or urea. The modulation of both CFTR and ClC-2 mRNA by AVP, the main hormone involved in the regulation of body fluid osmolality, suggests the participation of these two chloride channels in the renal tubule transcellular chloride transport modulated by AVP.

Estenose congênita da veia cava inferior na região supra-hepática. Correção cirúrgica de um caso / Congenital stenosis of the inferior vena cava in the suprahepatic region. Surgical correction of a case

Menino de 4 anos de idade, portador de estenose congenita da regiao supra-hepatica da veia cava inferior, associada a cirrose hepatica precoce, apresentava hepato e esplenonegalia, ascite e circulacao venosa colateral abdominal como principais sinais clinicos. A angiografia da veia cava inferior mostrou lesao obstrutiva com reducao concentrica por diafragma membranoso. A remocao cirurgica da membrana foi realizada por abordagem da veia cava, atraves de atriotomia direita, com auxilio de circulacao extracorporea. No periodo pos-operatorio, apresentou derrame pericardico seroso importante e ascite recorrente tratados com puncao evacuadora, albumina humana e diureticos. Tres meses apos a operacao, o paciente encontrava-se assintomatico.Destaca-se a importancia de diagnosticar e tratar precocemente esta rara anomalia congenita, que pode provocar lesao hepatica irreversivel