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Updated: Jul 14, 2026
Isolation of Monocyte-Macrophage Lineage Cells from Rat Bones by Secondary Adherence Method
Published on: July 13, 2022
Enhanced osteolytic potential of monocytes/macrophages derived from bone marrow after particle stimulation
Yasunobu Tamaki1, Kan Sasaki, Akiko Sasaki
1Department of Orthopaedic Surgery, Yamagata University School of Medicine, Yamagata 990-9585, Japan. ytamaki@med.id.yamagata-u.ac.jp
Background:
Total hip replacement can be complicated by periprosthetic osteolysis. Monocytes/macrophages play a major role in the formation of the foreign body granulomas induced by wear debris. We hypothesized that periprosthetic monocytes/macrophages do not only accelerate inflammatory and osteoclast-mediated osteolytic processes, but also resorb periprosthetic bone directly by themselves. This study was designed to evaluate the osteolytic potential in vitro of monocytes/macrophages derived from bone marrow.
Methods:
Monocytes/macrophages were produced by filtration of rat bone marrow cells, followed by culture in the presence of macrophage-colony stimulating factor (M-CSF). Monocyte/macrophage properties were ascertained using immunocytochemistry and phagocytic activity. Osteolytic cytokines and extracellular matrix degrading proteinases were quantified at the mRNA level.
Results:
Adherent cell fraction was immunoreactive for the monocyte/macrophage specific marker CD68 and active in the phagocytosis of carbon particles up to 72 h. They also showed immunoreactivity to cathepsin K, IL-1beta, IL-6, and M-CSF, but mostly did not react to TRAP. mRNA levels of osteolytic cytokines and extracellular matrix degrading proteinases were enhanced, but that of RANKL were not. Monocytes/macrophages resorbed dentine discs and carbonated calcium phosphate was very actively resorbed after stimulation with titanium particles.
Discussion:
Harvested bone marrow cells expressed monocyte/macrophage phenotype, but not osteoclastic markers. The capacity of these cathepsin-K-positive phagocytic cells to resorb dentine discs and carbonated calcium phosphate in vitro suggests a direct role of monocytes/macrophages in bone resorption and periprosthetic osteolysis. The finding supports our hypothesis and previous histomorphometric observations on the presence of such osteolytic macrophages in vivo around loosening prosthesis.
Insights
Monocytes/macrophages directly resorb bone, contributing to periprosthetic osteolysis after hip replacement. These cells, expressing cathepsin K, actively break down bone material in vitro, supporting their direct role in bone loss.
Area of Science:
- Immunology
- Orthopedic Surgery
- Cell Biology
Background:
- Total hip replacement can lead to periprosthetic osteolysis.
- Monocytes/macrophages are implicated in foreign body granuloma formation from wear debris.
Purpose of the Study:
- To investigate the direct bone resorption potential of monocytes/macrophages in vitro.
- To test the hypothesis that these cells directly resorb periprosthetic bone.
Main Methods:
- Bone marrow cells were cultured with macrophage-colony stimulating factor (M-CSF) to derive monocytes/macrophages.
- Immunocytochemistry and phagocytic assays assessed cell properties.
- mRNA levels of osteolytic cytokines and proteinases were quantified.
Main Results:
- Derived cells exhibited monocyte/macrophage markers (CD68) and phagocytic activity.
- Cells expressed cathepsin K and osteolytic cytokines (IL-1beta, IL-6, M-CSF).
- Monocytes/macrophages actively resorbed dentine discs and calcium phosphate, especially after titanium particle stimulation.
Conclusions:
- Bone marrow-derived monocytes/macrophages possess direct bone resorption capacity.
- Cathepsin K-positive phagocytic cells contribute to bone resorption and periprosthetic osteolysis.
- Findings support a direct role for macrophages in vivo bone loss around loosening prostheses.
