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Bone cells required for osteoclastic resorption but not for osteoclastic differentiation
J M Owens1, A C Gallagher, T J Chambers
1Department of Histopathology, St. George's Hospital Medical School, London, United Kingdom.
Biochemical and Biophysical Research Communications
|May 15, 1996
Summary
Osteoclast formation may not require osteoblastic cells. Hemopoietic spleen cells, induced by specific factors, develop osteoclastic traits but need osteoblasts to resorb bone, suggesting osteoblasts regulate mature osteoclast activity.
Area of Science:
- Cell Biology
- Bone Biology
- Hematology
Background:
- Osteoblastic cells are traditionally considered crucial for osteoclast formation.
- The precise role of osteoblasts in initiating osteoclastogenesis remains debated.
Purpose of the Study:
- To investigate osteoclast formation in hemopoietic tissue without osteoblastic cells.
- To determine if osteoblasts are essential for the initial differentiation of osteoclast precursors.
Main Methods:
- Cultures of hemopoietic mouse spleen cells were treated with prostaglandin E2 and 1,25(OH)2 vitamin D3.
- Spleen stromal cells were compared to bone marrow stromal cells for their ability to induce calcitonin-receptor positive (CTRP) cells.
- CTRP cells were assessed for bone resorption activity with and without osteoblast co-culture.
Main Results:
- Prostaglandin E2 and 1,25(OH)2 vitamin D3 induced large numbers of CTRP cells in hemopoietic mouse spleen cultures.
- Spleen stromal cells demonstrated equivalent CTRP-cell induction capacity compared to bone marrow stromal cells.
- Induced CTRP cells from spleen did not resorb bone independently but became fully resorptive upon addition of osteoblasts.
Conclusions:
- Osteoclast formation can be initiated from hemopoietic cells independently of osteoblastic cells.
- Osteoblasts are not essential for the formation of osteoclast precursors but are required for activating and regulating their bone-resorbing function.
- This suggests a regulatory role for osteoblasts in mature osteoclast activity rather than a primary role in their genesis.