[Platelet and endothelial cell-derived microparticles in steroid-induced osteonecrosis of the femoral head of rabbit model].
OBJECTIVE
To explore the relationship between the alterations of platelet-derived microparticles (PMPs) and endothelial cell-derived microparticles (EMPs) and steroid-induced osteonecrosis of the femoral head.


METHODS
Forty-four adult Japanese white rabbits were randomly divided into 2 groups: experimental group (n = 44), injected intramuscularly once with 20 mg/kg of methylprednisolone acetate, and control group (n = 28) injected with normal saline of the same dose. Blood samples were collected from the auricular vein while the animals were in a fasting state in early morning prior to experiment (week 0), and 2, 4, and 8 weeks after the injection. The levels of prothrombin time (PT), activated partial prothrombin time (APTT), and anti-thrombokinase-III (AT-III) were examined. Plasma was ultra-centrifuged and the circulating platelet and EMPs were isolated to undergo flow cytometry to detect the amounts of CD31, CD42a, CD54, and CD62E. 1, 2, 4, and 8 week after the injection 6 rabbits from the experimental group and 4 rabbits from the control group were sacrificed respectively and their femoral heads were taken out to undergo histopathologic examination with HE staining and microthrombus and elastic fiber staining.


RESULTS
The PT, APTT, and AT-III levels increased significantly 1 to 8 weeks after the injection. The numbers of EMPs and PMPs were also increased markedly after steroid administration. Histopathologic examination demonstrated an accumulation of bone marrow cell debris, presence bone empty lacunae in the trabeculae 1 week after the steroid injection. 2, 4, and 8 weeks after the steroid injection the bone necrosis was remarkable, fatty degeneration of bone marrow cells occurred, the diameter of fat cells increased, and the area ratio of fatty cells became higher. MSB staining was positive.


CONCLUSIONS
High dose glucocorticosteroid increases the levels of PMPs and EMPs that may be related to hypercoagulability and thrombosis in microcirculation and play an important role in steroid-induced osteonecrosis. MP can be considered a true target in the pharmacological control of steroid-induced osteonecrosis.
Kang
Peng-de
PD
Department of Orthopedics, West China Hospital of Sichuan University, Chengdu 610041, China.
Shen
Bin
B
Yang
Jing
J
Dang
Hong-sheng
HS
Pei
Fu-xing
FX
D000818:Animals; D000990:Antithrombin III / Q000032:analysis; D001792:Blood Platelets / Q000378:metabolism / Q000473:pathology*; D004195:Disease Models, Animal; D019040:E-Selectin / Q000032:analysis; D042783:Endothelial Cells / Q000378:metabolism / Q000473:pathology*; D005271:Femur Head Necrosis / Q000097:blood / Q000139:chemically induced / Q000503:physiopathology*; D005434:Flow Cytometry; D005938:Glucocorticoids; D018799:Intercellular Adhesion Molecule-1 / Q000032:analysis; D008775:Methylprednisolone / Q000031:analogs & derivatives; D000077555:Methylprednisolone Acetate; D010314:Partial Thromboplastin Time; D010316:Particle Size; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000032:analysis; D011517:Prothrombin Time; D011817:Rabbits
D019040:E-Selectin; D005938:Glucocorticoids; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D019038:Platelet Glycoprotein GPIb-IX Complex; D018799:Intercellular Adhesion Molecule-1; D000077555:Methylprednisolone Acetate; D000990:Antithrombin III; D008775:Methylprednisolone