3.2 Heat stress and LPS triggered HPMEC apoptosis via activating endothelial glycocalyx degradation
Changes in ultrastructure and apoptosis of HPMEC The ultrastructure of HPMEC was next observed to estimate the effects of heat stress and LPS om HPMEC apoptosis (Figure 2A ). Normal cellular structures were observed in CON group. In model groups, cells tended to generate characteristics of apoptosis such as swollen, broken membranes, abnormal organelles including nucleus, mitochondria and endoplasmic reticulum (Figure 2A ). Cells assigned to HPSE were more obvious but cells assigned to UFH were milder than HS+LPS group (Figure 2A ). These results suggested that an altered structure in HPMEC as a result of stimulation of heat stress and LPS.
Evidence suggested that heat stress may lead to cellular apoptosis,23 we next analyzed HPMEC activities through flow cytometry using Annexin V-FITC/PI staining. As expected, assignment of HPMEC with heat stress and LPS increased apoptotic rates in both HPSE and UFH treatment, compared with CON group (P < 0.05) (Figure 2B,C ). This increase is more pronounced in HPSE group (P < 0.05) (Figure 2B,C ), suggesting potential effects of damaged glycocalyx on HPMEC apoptosis.