Impairment of two types of circulating endothelial progenitor cells in patients with glucocorticoidinduced avascular osteonecrosis of the femoral head

Abstract

Objective To investigate whether the functions of two types of endothelial progenitor cells (EPCs) were changed in glucocorticoid-induced avascular osteonecrosis of the femoral head (ANFH) and to explore the role they played in regional endothelial dysfunction.Methods Early EPCs and endothelial colony forming cells (ECFCs) obtained from 33 patients with glucocorticoid-induced ANFH and 33 ageand sex-matched control subjects were isolated,in vitro cultured and characterized by immunofluorescence.Colony forming units,growth kinetics,migratory capacity,tube formation capacity and cytokine levels in the supernatants of two types of EPCs were assayed in glucocorticoid-induced ANFH and control subjects.Results The number of EPCs colonies formed by two types of EPCs was decreased in glucocorticoid-induced ANFH patients (2.42 ± 1.46 colonies/well versus 4.52 ±2.00 colonies/well,P ＜0.05 and 0.62 ±0.55 colonies/well versus 1.12 ± 0.82 colonies/well,P ＜ 0.05,respectively).Early EPCs from ANFH patients showed impaired migratory capacity [ 63.8 ± 11.7 versus 152.3 ± 12.4 ( P ＜ 0.01 ) ] and VEGF secretion [ (50.8 ± 7.2) ng/L versus ( 62.8 ± 10.1 ) ng/L,P ＜ 0.01 ].ECFCs from glucocorticoid-induced ANFH patients showed impaired proliferation rate ( P ＜ 0.05) and tube formation capacity [ 7.1 ±2.7 versus 23.8 ±4.3 ( P ＜0.01 ) ].Conclusion The functions of both early EPCs and ECFCs were impaired in glucocorticoid-induced ANFH,and their distinct reduced capacity profiles may reflect different roles they played in regional endothelial dysfunction of glucocorticoid-induced ANFH. Key words: Glucocorticoids; Femur head necrosis; Endothelial progenitor cells