Characteristics of human adrenal microvascular endothelial cells in morphology, phenotypes, and function

Objective: To investigate the phenotypic and functional characteristics of human adrenal microvascular endothelial cells (AdrEC).

Methods: AdrEC were isolated and purified from a sample of human adrenal tissue by sub-cell clone method. The cells identified by flow cytometry for classical endothelial markers von Willebrand factor (vWF) and CD31, uptake of Dil-labeled acetylated low density lipoprotein (Dil-Ac-LDL), as well as phenotypes. The cell fenestrations were checked by scanning electron microscopy. The expressions of endogenous vascular endothelial growth factor (VEGF) mRNA and protein were detected by reverse transcription-polymerase chain reaction (RT-PCR) and immunocytochemistry. The glucocorticoid-induced cytotoxicities in different organs-derived microvascular endothelial cells were compared.

Results: Human AdrEC expressed those classical endothelial markers such as vWF, CD31, and uptake of Dil-Ac-LDL. The phenotypic analysis indicated that alpha-1 proteinase inhibitor, tumor necrosis factor receptor p55, and intercellular adhesion molecule-1 were expressed in human AdrEC. Scanning electron microscopy demonstrated that there were many microvilli and fenestrations on cellular surface. RT-PCR and immunocytochemistry showed that there was expression of endogenous VEGF in AdrEC. In response to glucocorticoid-induced cytotoxicity, microvascular endothelial cells (MVEC) derived from human brain were highly susceptible, MVEC derived from human lung and human liver sinusoidal endothelial cells were sub-sensitive, while AdrEC were highly resistant.

Conclusions: Human AdrEC are specially differentiated and have characteristics that are different from other organ-derived MVEC in phenotypes and functions.