Effect of glucocorticoids on the function of microvascular endothelial cells in the human femoral head bone

Background. The pathogenesis of glucocorticoid (GC)-induced osteonecrosis (ON) of the femoral head remains unclear. Recent research has suggested that it is closely associated with injured bone microvascular endothelial cells (BMECs). However, few studies have used BMECs to perform research pertaining ON of the femoral head. Objectives. The objective of this study was to investigate the functional changes of BMECs treated with a GC and to detect the changes in related genes using microarrays. Material and methods. Cells were isolated using an enzymatic method and identified with EC markers, such as von Willebrand factor (vWF), CD31 and vascular endothelial cadherin (VE-cadherin). Bone microvascular endothelial cells were treated with 0.1 mg/mL and 0.3 mg/mL of hydrocortisone to establish a GC-damaged model of BMECs. The mRNA microarrays were used to detect the differential expression profiles between BMECs with and without GC damage. Results. Primary cells appeared as having a cobblestone-like morphology. Immunofluorescence staining revealed that the cells were 100% positive for vWF and CD31, and near 100% positive for VE-cadherin. It also confirmed that the cells were BMECs. Bone microvascular endothelial cells treated with 0.1 mg/mL of hydrocortisone showed shrinkage, and those treated with 0.3 mg/mL of hydrocortisone mostly showed apoptosis. The mRNA microarray showed that genes associated with endothelial cells, such as endothelin 1 (ET-1) receptor, angiotensin II (AII) receptor, intercellular adhesion molecule 1 (ICAM-1), and plasminogen activator inhibitor 1 (PAI-1), were upregulated, and genes associated with endothelial nitric oxide synthase (eNOS), endothelin 1 (ET-1), prostaglandin I-2 (PGI(2)) synthase, PGI(2) receptor, vascular endothelial growth factor (VEGF), prostaglandin E (PGE) synthase, and PGE receptor were downregulated. The results of quantitative polymerase chain reaction (qPCR) validation were consistent with the findings of mRNA microarrays. Conclusions. Glucocorticoids promoted BMECs to express vasoconstrictors and procoagulant factors and related receptors, and decreased the expression of vasodilators and their receptors.