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Osteoblast-like cell line maintains in vitro rat peritoneal mast cell viability and functional activity
F Levi-Schaffer1, Z Bar-Shavit
1Department of Pharmacology, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Abstract:
We studied the ability of the rat osteosarcoma derived cell-line with osteoblastic properties ROS-17/2.8 (ROS) to maintain in vitro rat peritoneal mast cells (MC) in a functional state. Highly purified (greater than 95%) MC were seeded on confluent ROS cells. The MC adhered tightly to the monolayers within a few hours and remained viable for at least 2 weeks, but did not proliferate. The MC retained their typical appearance, exhibiting highly granulated resting morphology when stained with alcian blue followed by safranin or with acidic toluidine blue. Furthermore, after 2 weeks, the MC were fully responsive to activation with compound 48/80 (3 micrograms/ml), releasing 75% of their histamine content, as compared to 3% in the absence of the secretagogue. Utilizing metabolically inactive ROS cells and prevention of contact between ROS and MC, we found that both release of factor(s) and cell-cell contact were required by ROS to exhibit their MC supporting activity. Various other cells and cell lines were unable to support MC viability. On the other hand, as demonstrated before, 3T3 fibroblasts were capable of promoting MC viability. Thus, MC viability and functional activity are specifically maintained by fibroblastic and osteoblastic cells. The abundance of MC in bone, and their participation in bone remodelling raise the possibility of physiological and pathological significance to interactions between MC and osteoblasts.
Insights
Osteoblasts and fibroblasts can maintain mast cells (MC) in a functional state. This interaction, requiring both cell contact and secreted factors, suggests a role for MC in bone remodeling.
Area of Science:
- Cell Biology
- Immunology
- Bone Biology
Background:
- Mast cells (MC) are immune cells found in bone, involved in bone remodeling.
- The specific interactions between MC and osteoblasts (bone-forming cells) are not fully understood.
Purpose of the Study:
- To investigate the ability of osteoblastic cells to support the viability and function of rat peritoneal mast cells in vitro.
- To determine the mechanisms by which osteoblastic cells support mast cells.
Main Methods:
- Rat peritoneal mast cells (MC) were co-cultured with ROS-17/2.8 osteosarcoma cells (ROS).
- Mast cell viability, morphology, and histamine release in response to compound 48/80 were assessed.
- Experiments using inactivated ROS cells and preventing cell-cell contact were performed to elucidate the supporting mechanisms.
Main Results:
- Mast cells adhered to and remained viable on ROS cell monolayers for at least 2 weeks without proliferation.
- Mast cells retained their granulated morphology and responded robustly to histamine secretagogues.
- Both cell-cell contact and soluble factors released by ROS cells were necessary for supporting mast cell activity.
- Fibroblasts also supported mast cell viability, but other cell types did not.
Conclusions:
- Osteoblastic cells, like fibroblasts, can specifically maintain the viability and functional activity of mast cells in vitro.
- The interaction involves both direct cell-cell contact and secreted factors.
- These findings highlight the potential physiological and pathological significance of mast cell-osteoblast interactions in bone biology and remodeling.