Pericyte-derived microvesicles protects septic rats against lung injury

Objective To investigate the protective effect of pericyte (PC)-derived microvesicle (MV) on lung injury in septic rats. Methods PC-MV was harvested by differential centrifugation and identified by transmission electron microscopy (TEM) and flow cytometry (FCM). Forty SD rats of either sex (12~14 weeks old, about 220 g) were randomly divided into 4 groups (n=10): normal group, PC-MV control group (normal rats with PC-MV injection), sepsis group (cecal ligation puncture, CLP), and PC-MV treatment group(septic rats with PC-MV injection). The effects of PC-MV (1×107 per rat) on pulmonary vascular permeability in septic rats were observed by measuring the wet/dry weight ratio of lung and Evans blue dye exudation in lung tissue, those on pulmonary tissue function were determined by lung pathological sections and arterial blood gas analysis, and those on inflammation were observed by detecting the levels of inflammatory factors. Results Compared with the normal group, the pulmonary function was obviously impaired in the septic rats, which was manifested as destruction of lung tissue structure, exudation of a large number of red blood cells and inflammatory cells, and decrease of oxygen partial pressure (PaO2, 33.6%) and increase of carbon dioxide partial pressure in the arteries (PaCO2, 47.5%). In septic rats, pulmonary vascular permeability was significantly increased, which was manifested as increment of lung wet/dry weight ratio, increment of Evans blue permeability in the lung, and increased levels of TNF-α and IL-6 (P < 0.01). Exogenous PC-MV improved pulmonary structure, restored the arterial blood gas (compared with the normal group, PaO2: decreased by 17.7%; PaCO2: increased by 26.9%), reduced inflammatory factor exfiltration (compared with the sepsis group, TNF-α level: decreased by 10.7%; IL-6 level: decreased by 23.9%) in PC-MV treatment group when compared with the sepsis group), and significantly protected pulmonary function of septic rats. Conclusion PC-MV has a protective effect on lung injury in septic rats