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Arthritis Research and Therapy

, 12:R124

First Online: 25 June 2010Received: 12 January 2010Revised: 16 April 2010Accepted: 25 June 2010


IntroductionAvascular necrosis of the femoral head ANFH occurs variably after exposure to corticosteroids. Microvascular thrombosis is a common pathological finding. Since systemic thrombophilia is only weakly linked with ANFH, we propose that microvascular vessel pathology may be more related to local endothelial dysfunction and femoral head apoptosis. Corticosteroid effects on the endothelium and resultant apoptosis have been reported. We hypothesize that corticosteroids contribute to a differential gene expression in the femoral head in rats with early ANFH.

MethodsBesides bone marrow necrosis, which is a common sign in ANFH and reported in the early stages, we include the presence of apoptosis in this study as a criterion for diagnosing early disease. Forty Wistar Kyoto WKY rats were randomized to either a corticosteroid-treated group or an age-matched control group for six months. After sacrifice, the femoral heads were examined for ANFH. Total mRNA was extracted from femoral heads. Affymetrix exon array Santa Clara, CA, USA was performed on 15 selected RNA samples. Validation methods included RT-PCR and immunohistochemistry IHC.

ResultsAlthough rat exon array demonstrated a significant upregulation of 51 genes corticosteroid+-ANFH+ VS control, alpha-2-macroglobulin A2M gene was particularly over-expressed. Results were validated by RT-PCR and IHC. Importantly, A2M is known to share vascular, osteogenic and cartilage functions relevant for ANFH.

ConclusionsThe findings suggest that corticosteroid-induced ANFH in rats might be mediated by A2M. Investigation of A2M as a potential marker, and a treatment target, for early ANFH should be carried out.


ANFHavascular necrosis of the femoral head

BMP-1bone morphogenic protein-1

Col2A1collagen type II alpha-1

ΔCtcomparative threshold cycle


DEPCdiethyl pyrocarbonate

ECendothelial cells

FCfold change

G1group 1

G2group 2

G3group 3



MIAMelanoma Inhibitory Activity-1

OGPosteogenic growth peptide

PAI-1plasminogen activator inhibitor 1

PCAprinciple component analysis

PBSphosphate buffer solution

RTroom temperature

RT-PCRreal-time polymerase chain reaction

SEMstandard error of the mean

TDTterminal dexoynucleotidyl transferase

TUNELterminal dexoynucleotidyl transferase mediated deoxyuridine triphosphate biotin nick end labelling

WKYWistar Kyoto.

Electronic supplementary materialThe online version of this article doi:10.1186-ar3062 contains supplementary material, which is available to authorized users.

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Autor: Mohammad Amin Kerachian - Denis Cournoyer - Edward J Harvey - Terry Y Chow - Louis R Bégin - Ayoub Nahal - Chantal Sé


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