Perfusion microvessel density in the cerebral cortex of septic rats is negatively correlated with endothelial microparticles in circulating plasma

In sepsis, endothelial microparticles (EMPs) released from endothelial cells (ECs) participate in microcirculation dysfunction through pro-coagulant and pro-inflammatory effects, which can lead to sepsis-associated brain dysfunction. However, the relationship between EMPs and cerebral cortical perfusion microvessel density has not been explored. A closed cranial window was created in rats who were tended to until the cerebral cortex edema caused by preparation of the cranial window subsided, and the microvessel density was stable. A cecal ligation and puncture (CLP) sepsis procedure was then performed on day 6, post-surgery. At 12 and 24 h after the CLP, cerebral cortical perfusion microvessel density was measured with optical coherence tomography angiography (OCTA), followed by measurement of EMPs to evaluate the relationship between these factors. Microvessel density changed from 46.38 % ± 7.65 % on the day of surgery to 35.87 % ± 11.05 % on the second day and 36.71 % ± 11.38 % on the third day after surgery, and then increased daily. The microvessel density decreased to 27.20 % ± 8.50 % 24 h after CLP, which was significantly lower than that immediately and 12 h after CLP (P < 0.001). EMPs increased progressively at 12 and 24 h after CLP. Moreover, there was a negative correlation between EMPs and microvessel density (r=-0.56, P = 0.01). Edema and microvessel density decreased in the local cerebral cortex of the window and then gradually recovered after cranial window surgery. In sepsis, the perfusion microvessel density of the cerebral cortex negatively correlated with the EMPs. Therefore, the perfusion microvessel density can be indirectly evaluated by detecting the plasma EMP level.