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Acridine orange induces binucleation in chondrocytes
K Kusuzaki1, H Takeshita, H Murata
1Department of Orthopaedic Surgery, Kyoto Prefectural University of Medicine, Japan. kusu@basic.kpu-m.ac.jp
Osteoarthritis and Cartilage
|March 10, 2001
Summary
Acridine orange exposure in cultured chondrocytes leads to binucleation, likely through amitotic nuclear division of G2-arrested cells. This clarifies the mechanism behind binuclear cells in cartilage and chondrosarcomas.
Area of Science:
- Cell Biology
- Histology
Background:
- Binuclear cells are common in normal cartilage and chondrosarcomas, but their formation mechanism is poorly understood.
- Investigating chondrocyte binucleation provides insights into cartilage biology and potential neoplastic processes.
Purpose of the Study:
- To elucidate the mechanism of binucleation in chondrocytes.
- To utilize primary growth plate cartilage cells in a controlled culture setting.
Main Methods:
- Chondrocytes were exposed to acridine orange (AO), a DNA/RNA fluorescent dye that inhibits mitosis.
- Key parameters monitored included cell growth rate, hyperdiploid cell frequency (DNA cytofluorometry), mitotic index, BrdU labeling index, and binuclear cell frequency over 96 hours.
Main Results:
- Acridine orange significantly inhibited cell growth and mitosis, while increasing hyperdiploid and binuclear cell frequencies.
- Binuclear cell frequency increased up to sixfold compared to controls by 96 hours.
- Cellular proliferation markers recovered by 96 hours, suggesting a specific response to AO.
Conclusions:
- Binuclear chondrocytes in culture likely arise from G2-arrested cells undergoing amitotic nuclear division.
- The findings differentiate this mechanism from mitosis without cytokinesis or cell fusion.
- This study provides a potential mechanism for binucleation observed in both normal and neoplastic cartilage.