Concentration Polarization Of Atherogenic Lipids In Vessel In Zebrafish

Atherosclerotic cardiovascular disease is the leading cause of morbidity and mortality in worldwide. There is no complete explanation to the pathogenesis of this disease, however, many factors have been found closely related to the atherosclerosis. Although these factors explain the initiation and progression of atherosclerosis from a different sides, but it's difficult to revel the location of atherosclerosis, that is the lesions in humans develop preferentially at certain sites such as the curves, bifurcations and the straitness sites of arteries. Nevertheless, it has been well documented that early event leading to the genesis of atherosclerosis is the accumulation of cholesterol and other lipids within the intima. These lipid deposits are believed to be derived primarily from plasma lipoproteins, particularly low-density lipoproteins (LDL). A large number of computer simulations and in vitro experiments show that the main reason leading to the genesis of atherosclerosis is lipoprotein concentration polarization. And it is few to investigate the relations between them in vivo. The zebrafish have advantages that body is transparent after birth, the sexual maturity period is short, and the smaller individual to culture. And it is widely applied to the research development, which involve the nervous system, immune system and cardiovascular system, and the research of function or disease. In this research we use the transparent zebrafish to investigate the lipoprotein concentration polarization in vivo, and it will be a well model to investigate the relations between lipoprotein concentration polarization and atherosclerosis.In this paper, LDL with red fluorescence was injected into the optically transparent Flk1:GFP zebrafish larvae(Day 2,n=60). The flow and distributing of lipids was observed by the confocal microscope. The results show that the red fluorescent lipoproteins are flowing in the vessel luminal (57/60), compared to the control with no green fluorescent proteins, using confocal microscopy. That demonstrated that we can inject the lipids into the blood circulation in zabrefish to do the visual observation. The flow figure was doing the fluorescent quantitative analysis by Image Pro-Plus software. The analysis showed the LDL concentration is gradient distributing in the zebrefish vessel, that is the concentration of LDL is gradually decreasing from the luminal surface to the vessel axis, furthermore the surface concentration of LDL at the vessel wall is higher than that in the bulk ?ow in vessel, which is called lipid concentration polarization. However, the LDL concentration in the vascular bifurcation wall was significantly higher than that in the wall of straight vessel, but the concentration in the bulk flow was homogeneous.LDL is accumulated 2days after injection, and there are amount of deposition in the vascular bifurcation and bend, in which there was more severe lipid concentration polarization. The results demonstrated that the lipid concentration polarization promoted the initiation of AS.According the in vivo research confirmed that the lipoprotein concentration polarization was occurred in vasculature, and the LDL was deposited in the predilection regions of atherosclerosis, and provided a new method to study the AS. The flow and distribution of lipids within the intima and blood can be observed in vivo in zebrafih, so that we can investigate the important role of lipoprotein concentration polarization in the genesis and progression of atherosclerosis more intuitive.