Morphological and Biochemical Evidence for Apoptosis in the Terminal Hypertrophic Chondrocytes of the Growth Plate

Abstract

The purpose of this study was to investigate the mechanism of cell death in chondrocytes of the growth plate. In the degenerative chondrocyte zone of the growth plate, apoptotic chondrocytes were defeated by the in situ nick end labelling method, by DNA analysis in agarose gel, and by electron microscopy. The results of the in situ nick end labelling method and the occurrence of a ladder pattern of DNA in agarose gel analysis indicated the activation of endogenous endonucleases, resulting in DNA fragmentation. Electron micrographs showed the early morphological changes associated with apoptosis. This report presents both morphological and biochemical evidence for apoptosis in the terminal hypertrophic chondrocytes of the growth plate. These data suggest that apoptosis of degenerative chondrocytes may play an important role in the control of normal and pathological endochondral ossification.

Chondrocyte apoptosis enhanced at the growth plate: a physeal response to a diaphyseal fracture

“…Until now, opinions regarding the ultimate fate of terminally differentiated hypertrophic chondrocytes have been conflicting. Several studies have confirmed the occurrence of chondrocyte apoptosis both in vitro (Cheung et al 2003;Gibson et al 1997) and in vivo (Chrysis et al 2002;Ploumis et al 2004;Zenmyo et al 1996) and some review articles refer to apoptosis as being the most likely mechanism of hypertrophic chondrocyte deletion (Ballock and O'Keefe 2003;Forriol and Shapiro 2005;Shum and Nuckolls 2002). However, other authors refer to variants of physiological cell death showing an ultrastructural morphological appearance different from the hallmark features of classical apoptosis (Roach et al 2004;Clarke 1999, 2000;Shapiro et al 2005).…”

“…Several previous studies have successfully used this assay to identify apoptosis in chondrocytes (Chrysis et al 2002;Ploumis et al 2004;Silvestrini et al 1998;Zenmyo et al 1996). Gavrieli and collaborators (1992) have established this method as a specific, simple and reproducible tool for the in situ detection of programmed cell death at a single-cell level, whilst also preserving tissue architecture and enabling the additional visualisation of apoptotic morphological changes.…”

Cell proliferation and death of growth plate chondrocyte caused by ischemia and reperfusion

“…In trabecular bone, longitudinal growth occurs by endochondral ossification, which involves proliferation, 13,16 dif- ferentiation, 24,25 and death 17,18,20 of growth plate chondrocytes. It is regulated by various factors such as hormones, 26 cytokines, 27,28 and programmed DNA signals.…”

“…17,18 The death of normal growth plate chondrocytes is currently regarded as apoptosis because their death contributes to homeostasis of longitudinal growth of the bone. 19,20 One common method for detecting apoptosis is by terminal deoxynucleotidyltransferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL). 10,21 In conditions caused by ischemia and reperfusion, cells exhibit necrosis as well as apoptosis.…”

“…23 Therefore, we observed the morphologic changes in the cells by transmission electron microscopy (TEM) and elucidated how chondrocytes die. 20 search Facilities for Laboratory Animal Science, Hiroshima University School of Medicine. The right hindlimbs were subjected for surgery.…”