PT  - JOURNAL ARTICLE
AU  - TAMON KABATA
AU  - TADAMI MATSUMOTO
AU  - SHINICHI YAGISHITA
AU  - TOMOHIKO WAKAYAMA
AU  - SHOICHI ISEKI
AU  - KATSURO TOMITA
TI  - Vascular Endothelial Growth Factor in Rabbits During Development of Corticosteroid-Induced Osteonecrosis: A Controlled Experiment
AID  - 10.3899/jrheum.070838
DP  - 2008 Dec 01
TA  - The Journal of Rheumatology
PG  - 2383--2390
VI  - 35
IP  - 12
4099  - http://www.jrheum.org/content/35/12/2383.short
4100  - http://www.jrheum.org/content/35/12/2383.full
SO  - J Rheumatol2008 Dec 01; 35
AB  - Objective Vascular endothelial growth factor (VEGF) is an angiogenic promoter that is rapidly induced as a response to local hypoxia. We investigated VEGF expression in rabbits in a controlled experiment to clarify the onset of ischemic events in corticosteroid-induced osteonecrosis (ON). Methods Ninety-nine mature Japanese white rabbits were divided into 6 treatment groups and an untreated control group. The treatment groups received a single intramuscular injection of 4 mg/kg methylprednisolone acetate; they were euthanized at different times, and tissue samples were obtained from their femora. We examined the development of ON and the expression of VEGF using histopathology, immunohistochemistry, Northern blot analysis, and Western blot analysis. Results On histopathological examination, the earliest indication of ON was 5 days after the corticosteroid treatment. The frequency of ON occurrence reached a plateau at or after Week 1. VEGF expression was accompanied by the development of ON. VEGF-positive cells detected by immunohistochemistry were found among bone marrow cells, frequently located in the area surrounding ON, suggesting that VEGF production was switched on as a result of the ischemic events that cause ON. The level of VEGF-mRNA expression indicated by Northern blot analysis peaked at 3 days after the corticosteroid treatment and decreased gradually to the levels present in the control group at 7 days after treatment. Western blot analysis revealed VEGF protein production at 3 days after the corticosteroid treatments. Levels of VEGF expression 2 weeks or more after the corticosteroid treatment were almost the same as in the control group. Conclusion We observed early expression of VEGF in the cells around the corticosteroid-induced ON lesions in rabbits. These results suggest that the ischemic events that cause ON begin soon after the initial corticosteroid treatment.