Distinct Effects of Royal Jelly on Human Endothelial Cells Under High Glucose Condition

To assess different effects of royal Jelly in protecting the human endothelial cells from high glucose level, human umbilical vein endothelial cells were exposed to various concentrations of royal jelly, from 0.625 to 10 mg/mL, at the presence of 5 and 30 mM glucose contents over a course of 72 h. In addition to cell viability assessment by conventional MTT assay, we also analyzed the feature of stemness by expression of Sox-2 and CD133 factors. Moreover, fatty acid profile, the expression of autophagy-related factor, namely microtubule-associated protein light chain 3 and activity of metalloproteinase 2 and 9 and were investigated. Royal jelly supplementation at the concentrations lower than 2.5 mg/mL did not influence the survival rate of cells and partially blunted the cytotoxic effects of 30 mM glucose. The expression of CD133 and Sox-2 factors were increased by royal jelly alone. Interestingly, an up-regulated expression of Sox-2 (58.8 ± 4%) coincided with a reduction in the levels of CD133 (15.1 ± 8.3%) in the combined treatment. We notified that the contents of palmitate and trans-palmitate as well as linoleate decreased by 30 mM glucose content while cis-palmitate levels increased when RJ returned them to near-normal levels (p < 0.05). The expression of autophagy marker was prominently induced in the presence of royal jelly in both conditions (p < 0.05). The glucose-induced activity of metalloproteinases was also reduced. Royal jelly is able to attenuate the abnormal status of 30 mM glucose condition in endothelial cells by different mechanisms.