Abstract
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. 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. 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. 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 I2 (PGI2) synthase, PGI2 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. Glucocorticoids promoted BMECs to express vasoconstrictors and procoagulant factors and related receptors, and decreased the expression of vasodilators and their receptors.
Highlights
Non-traumatic avascular necrosis of the femoral head is a refractory hip joint lesion
Bone microvascular endothelial cells were treated with 0.1 mg/mL and 0.3 mg/mL of hydrocortisone to establish a GCdamaged model of bone microvascular endothelial cells (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
Summary
Non-traumatic avascular necrosis of the femoral head is a refractory hip joint lesion. More and more authors believe that steroid-induced ONFH is closely related to the damage to bone microvascular endothelial cells (BMECs) in the femoral head. Endothelial cells have endocrine functions[19]; they can synthesize and secrete various bioactive substances and play an important role in regulating local blood flow and body fluid balance. Their functions involve vasoconstriction, coagulation and fibrinolysis, angiogenesis and cell proliferation, oxidative stress, cell adhesion, and inflammatory mediation, which include endothelial nitric oxide synthase (eNOS), prostaglandin I2 (PGI2), endothelin 1 (ET-1), intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), tissue plasminogen activator (t-PA), plasminogen activator inhibitor 1 (PAI-1), vascular endothelial growth factor (VEGF), von Willebrand factor (vWF), fibroblast growth factor (FGF), interleukin 1 (IL-1), and IL-6. Few studies have used BMECs to perform research pertaining ON of the femoral head
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