Myofibroblast Forms Atherosclerotic Plaques

For decades, smooth muscle cells (SMCs) and macrophages are considered as the main contributors to atherosclerotic plaques. However, we found that in the human coronary atherosclerotic plaques, SMCs were few, while lots of myofibroblasts infiltrated in the intima near the lumen (fibrous cap) and their distribution was highly positive related to intimal thickness. In addition to lots of foam cells formation, collagen fibers were forming in the thickening intima near the lumen (fibrous cap), and denaturing or calcifying gradually far from the lumen, which evolved into various complex plaques. In vitro, myofibroblasts could actively take lots of low-density lipoprotein (LDL) to enhance proliferation. Lots of collagen fibers, foam cells and extracellular lipids accumulation emerged in myofibroblasts cultured with 5% FBS high glucose DMEM without adding modified LDL. It is consistent with the characteristics of human coronary atherosclerotic plaques. It is the first time that lipid rich plaques with lots of foam cells, extracellular lipids and collagen fibers formed in vitro. It demonstrated that myofibroblast should be the direct and main source of collagen fibers, foam cells and extracellular lipids. This suggests that atherosclerosis is not as complicated as previously considered, and it might be mainly a process of myofibroblast remodeling to vascular injury caused by various risk factors. This study made the pathogenesis of atherosclerosis clearer. It would provide a target cell for future treatments of atherosclerotic diseases. In vitro atherosclerotic plaques model formed by human myofibroblasts would be an efficient and convenient way to study atherosclerosis.

Optimization of Yarrowia lipolytica-based consolidated biocatalyst through synthetic biology approach: transcription units and signal peptides shuffling

Background: Nowadays considerable effort is being pursued towards development of consolidated microbial biocatalysts that will be able to utilize complex, non-pretreated substrates and produce valuable compounds. In such engineered microbes, synthesis of extracellular hydrolases may be fine-tuned by different approaches, like strength of promoter, type of secretory tag, gene copy number etc. In this study, we investigated if organization of a multi-element expression cassette impacts the resultant Y. lipolytica transformants’ phenotype, presuming that different variants of the cassette are composed of the same regulatory elements and encode the same hydrolases. Results: To this end, Y. lipolytica cells were transformed with expression cassettes bearing a pair of genes encoding exactly the same mature amylases, but fused to four different signal peptides (SP), and located interchangeably in either first or second position of a synthetic DNA construction. The resultant strains were tested for growth on raw and pre-treated complex substrates of different plant origin for comprehensive examination of the strains’ acquired characteristics. The best strain’s performance was tested in batch bioreactor cultivations for growth and lipids accumulation. Conclusions: Based on the conducted research we concluded that the positional order of transcription units (TU) and the type of exploited SP affect final characteristics of the resultant consolidated biocatalyst strains, and thus could be considered as additional factors to be evaluated upon consolidated biocatalysts optimization.

LIPIDS ACCUMULATION OF CHLORELLA VULGARIS UNDER VARIABLE LIGHTING CONDITIONS

The cultivation of microalgae is now an intensively developed research area. Some species of microalgae under appropriate conditions accumulate large amounts of lipids in the cells, which may be a suitable feedstock for biodiesel production. The cultures of microalgae for lipids production should be cultivated in specific physicochemical conditions. The most important environmental parameters affecting the algae growth are: nutrients, lighting, reaction, turbulence, salinity and temperature. Periodic changes in lighting is a key parameter that have a significant effect on cells density and lipid accumulation. The mechanism of this action depends on intensity of light and its spectral composition. To produce 3rd and 4th generation biofuels, a better understanding of the relationship between light conditions and yield of lipids accumulation is necessary. The aim of the study was to determine the effects of variable lighting conditions for lipids accumulation of microalgae Chlorella vulgaris and to determine the most effective lighting parameters. The study confirmed the possibility of using the lighting shock conditions to maximize lipids accumulation in algae Chlorella vulgaris cells. In the study, 33.18% of lipids were obtained from biomass culturing with red light-emitting diodes (LEDs), which was 22% more than obtained with white continuous lighting.