Increased osteocyte apoptosis during the development of femoral head osteonecrosis in spontaneously hypertensive rats.
ABSTRACT We investigated the presence of osteocyte apoptosis in the necrotic trabeculae of the femoral head of spontaneously hypertensive rat (SHR) using the in situ nick end labeling (TUNEL) method and transmission electron microscopy. The occurrence of osteonecrosis and ossification disturbance was significantly higher in SHR compared with Wistar Kyoto (WKY) rats, and Wistar (WT) rats used as control animals (P < 0.01). A high population of TUNEL positive osteocytes was detected mainly in 10- and 15-week-old SHRs. Sectioned examination of the femoral head of SHRs and WKY rats by electron microscopy revealed apoptotic cell appearances such as aggregation of chromatin particles and lipid formation. In contrast, a positive reaction was significantly lower in osteocytes in the femoral heads of WT rats (P < 0.01). Our results indicate that apoptosis forms an important component of the global pathologic process affecting the femoral head of SHR, which leads to osteonecrosis in this region.
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Article: Bone microdamage and cell apoptosis.[Show abstract] [Hide abstract]
ABSTRACT: Accumulation of microdamage in bone leads to the reduced strength of our skeleton. In health, bone adapts to the prevailing mechanical needs of the organism and is also capable of self-repair, sensing, removing and replacing damaged or mechanically insufficient volumes of bone. In disease and old age these characteristics are reduced. In order to undertake both of the processes of functional adaptation and repair the bone resorbing and forming cells must be very accurately targeted to areas of physiological need. The mechanism by which cells are precisely targeted to areas requiring repair is both clinically relevant and poorly understood. The osteocyte has been assumed to play a role in sensing damage and signaling for its removal, due largely to its abundance throughout the mineralized bone matrix. However, until recently there has been little evidence that osteocyte function is modified in the vicinity of the microdamage. Here I outline the possibility that the targeted removal of bone containing microcracks might involve signals derived from the apoptotic death of the osteocyte. I shall discuss data that support or refute this view and will consider the possible molecular mechanisms by which controlled cell death might contribute to the signals for repair in the light of work involving cells in bone and other tissue systems.European cells & materials 01/2004; 6:46-55; discusssion 55. · 4.56 Impact Factor
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ABSTRACT: Ossification disturbance in femoral head reportedly is seen in the Spontaneously Hypertensive rats (SHR) between ages of 10 and 20 weeks. We investigated serum and tissue levels of insulin-like growth factor-1 (IGF-1) and vascular endothelial growth factor (VEGF) in SHR relevant to the ossification disturbance and osteonecrosis of the femoral head. Serum levels of IGF-1 and VEGF were significantly lower in SHR than in Wistar Kyoto rats (WKY) at weeks 5, 10, 15 and 20 (p<0.005). The incidence of histological ossification disturbance of the femoral head was higher in SHR (59%) than in WKY (40%) at week 20. Lower serum and local levels of VEGF in SHR appeared to be related to the incomplete ossification of the femoral heads. Immunohistochemical study showed significantly lower numbers of IGF-1 and VEGF positive chondrocytes in the femoral epiphyseal cartilage of SHR than in those of WKY at weeks 10, 15 and 20. Our results suggest that local and/or systemic levels of IGF-1 and VEGF between ages of 5 and 20 weeks might play roles in the pathogenesis of ossifi cation disturbance of the femoral head in SHR.Acta medica Okayama 06/2006; 60(3):141-8. · 0.65 Impact Factor
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ABSTRACT: Osteonecrosis (ON) or avascular necrosis (AVN) is a common bone metabolic disorder, mostly affecting femoral head. Although many biological, biophysical, and surgical methods have been tested to preserve the femoral head with ON, none has been proven fully satisfactory. It lacks consensus on an optimal approach for treatment. This is due, at least in part, to the lack of ability to systematically compare treatment efficacy using an ideal animal model that mimics full-range osteonecrosis of femoral head (ONFH) in humans with high incidence of joint collapse accompanied by reparative reaction adjacent to the necrotic bone in a reproducible and accessible way. A number of preclinical animal ON models have been established for testing potential efficacy of various modalities developed for prevention and treatment of ON before introduction into clinics for potential applications. This paper describes a number of different methods for creating animal experimental ON models. Advantages and disadvantages of such models are also discussed as reference for future research in battle against this important medical condition.Rheumatology International 02/2011; 31(8):983-94. · 2.21 Impact Factor