Metabolomics-on-a-chip approach to study hepatotoxicity of DDT, permethrin and their mixtures.

Despite the diversity of studies on pesticide toxicities, there is a serious lack of information concerning the toxic effect of pesticides mixtures. Dichlorodiphenyl-trichloroethane (DDT) and permethrin (PMT) are among the most prevalent pesticides in the environment and have been the subject of several toxicological studies. However, there are no data on the toxicity of their mixtures. In this study, we used an approach combining cell culture in microfluidic biochips with gas chromatography-mass spectrometry metabolomics profiling to investigate the biomarkers of toxicity of DDT, PMT and their mixtures. All parameters observed indicated that no significant effect was observed in hepatocytes cultures exposed to low doses (15 µm) of DDT and PMT. Conversely, combined low doses induce moderate oxidative stress and cell death. The toxic signature of high doses of pesticides (150 µm) was illustrated by severe oxidative stress and cell mortality. Metabolomics profiling revealed that hepatocytes exposure to DDT150, PMT150 and DDT150 and PMT150 cause important modulation in intermediates of glutathione pathway and tricarboxylic acid cycle, amino acids and metabolites associated to hepatic necrosis and inflammation (α-ketoglutarate, arginine and 2-hydroxybutyrate). These changes were more striking in the combined group. Finally, DDT150 led to a significant increase of benzoate, decanoate, octanoate, palmitate, stearate and tetradecanoate, which illustrates the estrogen modulation. This study demonstrates the potential of metabolomics-on-a-chip approach to improve knowledge on the mode of action of pesticides.

Alginate-Based Cell Microencapsulation for Tissue Engineering and Regenerative Medicine.

Increasing numbers of requests for transplantable organs and their scarcity has led to a pressing need to find alternative solutions to standard transplantation. An appealing but challenging proposal came from the fields of tissue engineering and regenerative medicine, the purpose of which is to build tissues/organs from scratch in the laboratory and use them as either permanent substitutes for direct implantation into the patient's body, or as temporary substitutes to bridge patients until organ regeneration or transplantation. Using bioartificial constructs requires administration of immunosuppressant therapies to prevent rejection by the recipient. Microencapsulation has been identified as promising technology for immunoisolating biological materials from immune system attacks by the patient. It is based on entrapping cellular material within a spherical semipermeable polymeric scaffold. This latter defines the boundary between the internal native-like environment and the external "aggressive" one. The scaffold thus acts like a selective filter that makes possible an appropriate supply of nutrients and oxygen to the cellular constructs, while blocking the passage for adverse molecules. Alginate, which is a natural polymer, is the main biomaterial used in this context. Its excellent properties and mild gelation ability provide suitable conditions for supporting viability and preserving the functionalities of the cellular- engineered constructs over long periods. Although much remains to be done before bringing microencapsulated constructs into clinical practice, an increasing number of applications for alginate-based microencapsulation in numerous medical areas confirm the considerable potential for this technology in providing a cure for transplant in patients that excludes immunosuppressive therapies.

Novel human-derived extracellular matrix induces in vitro and in vivo vascularization and inhibits fibrosis.

The inability to vascularize engineered organs and revascularize areas of infarction has been a major roadblock to delivering successful regenerative medicine therapies to the clinic. These investigations detail an isolated human extracellular matrix derived from the placenta (hPM) that induces vasculogenesis in vitro and angiogenesis in vivo within bioengineered tissues, with significant immune reductive properties. Compositional analysis showed ECM components (fibrinogen, laminin), angiogenic cytokines (angiogenin, FGF), and immune-related cytokines (annexins, DEFA1) in near physiological ratios. Gene expression profiles of endothelial cells seeded onto the matrix displayed upregulation of angiogenic genes (TGFB1, VEGFA), remodeling genes (MMP9, LAMA5) and vascular development genes (HAND2, LECT1). Angiogenic networks displayed a time dependent stability in comparison to current in vitro approaches that degrade rapidly. In vivo, matrix-dosed bioscaffolds showed enhanced angiogenesis and significantly reduced fibrosis in comparison to current angiogenic biomaterials. Implementation of this human placenta derived extracellular matrix provides an alternative to Matrigel and, due to its human derivation, its development may have significant clinical applications leading to advances in therapeutic angiogenesis techniques and tissue engineering.