Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Gaber, S.
Chondrocyte apoptosis following growth plate stimulation after fracture
[ Diplomarbeit ] Medical University of Graz; 2008. pp. 92
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- Autor*innen der Med Uni Graz:
- Betreuer*innen:
- Weinberg Annelie-Martina
- Altmetrics:
- Abstract:
- Post-traumatic overgrowth of long bones is a common clinical phenomenon in paediatric traumatology and is to be expected when faced with a fractured growing bone. Accelerated bone growth after fracture is the result of an enhanced stimulation of the nearby growth plate. However, up till now the exact post-fractural reactions of the growth plate are poorly understood. This study aims to determine the impact of fracture on chondrocyte apoptosis in the growth plate. Fifty-six male Sprague-Dawley rats weighing between 100 and 120 g were randomly distributed into two main groups, the experimental and the control group, and these were further divided into 4 subgroups with 7 rats in each. Animals in the experimental group sustained a middiaphyseal closed fracture of the left tibia using a standardised guillotine. Euthanasia was performed 3, 10, 14 and 29 days after fracture. The control rodents were sacrificed at the same time. The left and right tibiae were harvested, fixed in formaldehyde, decalcified and embedded in paraffin. Finally, apoptotic chondrocytes of the proximal tibial growth plate were detected by the use of TUNEL staining, which labels DNA fragmentations, the hallmark of apoptosis. Apoptotic cell bodies were manually counted by means of light microscopy and the apoptosis percentage of physeal chondrocytes was statistically compared between the fractured bone, the intact contra-lateral bone and the control bone. The physeal apoptosis rate of the fractured bone was significantly higher than that of the intact contra-lateral bone (valid for all evaluated days) and that of the control bone (valid from day 10 onwards). Contra-lateral intact tibiae never showed physeal apoptosis rates which were significantly higher than that of the control tibiae. This study provides evidence that a middiaphyseal fracture influences the nearby growth plate by stimulating chondrocyte programmed cell death, which is associated with cartilage resorption and bone replacement. The lack of a significant difference between the intact contra-lateral bone and the intact control bone suggests that there is a local effect of the fracture which contributes to the higher apoptosis rate of the adjacent physis.