Co-culture models of endothelial cells, macrophages, and vascular smooth muscle cells for the study of the natural history of atherosclerosis

Background This work aims to present a fast, affordable, and reproducible three-cell co-culture system that could represent the different cellular mechanisms of atherosclerosis, extending from atherogenesis to pathological intimal thickening. Methods and results We built four culture models: (i) Culture model #1 (representing normal arterial intima), where human coronary artery endothelial cells were added on top of Matrigel-coated collagen type I matrix, (ii) Culture model #2 (representing atherogenesis), which demonstrated the subendothelial accumulation and oxidative modification of low-density lipoproteins (LDL), (iii) Culture model #3 (representing intimal xanthomas), which demonstrated the monocyte adhesion to the endothelial cell monolayer, transmigration into the subendothelial space, and transformation to lipid-laden macrophages, (iv) Culture model #4 (representing pathological intimal thickening), which incorporated multiple layers of human coronary artery smooth muscle cells within the matrix. Coupling this model with different shear stress conditions revealed the effect of low shear stress on the oxidative modification of LDL and the upregulation of pro-inflammatory molecules and matrix-degrading enzymes. Using electron microscopy, immunofluorescence confocal microscopy, protein and mRNA quantification assays, we showed that the behaviors exhibited by the endothelial cells, macrophages and vascular smooth muscle cells in these models were very similar to those exhibited by these cell types in nascent and intermediate atherosclerotic plaques in humans. The preparation time of the cultures was 24 hours. Conclusion We present three-cell co-culture models of human atherosclerosis. These models have the potential to allow cost- and time-effective investigations of the mechanobiology of atherosclerosis and new anti-atherosclerotic drug therapies

History and prospects of the physical synthesis of kesterite for photovoltaic applications

Through the years, kesterite Cu2ZnSn(S,Se)4 thin films have been fabricated using various physical synthesis technologies. Among them, sequential stacking or co-sputtering of precursors as well as sequential or co- evaporation of elemental sources have led to the achievement of high-efficient solar cells. In this work, we provide an up-to-date overview of the physical vapor technologies used to synthesize CZT(S,Se) thin films as absorber layers for photovoltaic applications. This review starts with an enumeration of the well-known pro- cesses used for the growth of CZT(S,Se) absorber layers. A historical description of the main issues limiting the efficiency and of the experimental pathways designed to prevent or limit these issues is presented and discussed. The discussion is articulated through the transition from a one-step synthesis process consisting in a high temperature deposition to a two-step synthesis process composed of (i) the deposition of a precursor film and (ii) a thermal annealing under S (sulfurization) or Se (selenization) atmosphere. To complete the de- scription, morphological properties, such as void formation and thin films blistering are discussed in relation with the synthesis protocols used. In addition, alternative methods for kesterite layers deposition are devel- oped such as pulsed laser deposition of composite targets and monograin growth by the molten salt method, both leading to a significant progress in device efficiency. A final discussion is dedicated to the description of promising process steps aiming at further improvements of solar cell efficiencies, such as alkali doping and alloying of kesterite for bandgap grading. As a result, this work highlights the growing increase of the kesterite-based solar cell efficiencies achieved over the recent years and offers a broad and updated overview of the physical vapor deposition technologies currently applied to the fabrication of performant CZT(S,Se) absorber layers