Phagocytic properties of bone marrow fibroblasts
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Abstract:
Phagocytic activity has been observed in cultured marrow derived adherent cells (MDAC). Characterization studies indicate that these populations consist largely of collagen-producing fibroblasts, having failed to reveal markers associated with mononuclear phagocytes (MNP). Phagocytic activity by MDAC was therefore investigated. Characterization studies again failed to demonstrate an Fc receptor and confirmed that human MDAC synthesize collagen in vitro. Phagocytic activity against polystyrene microspheres was observed in 40% of MDAC. Control studies using P-8 and WI-38 fibroblasts yielded similar results. MDAC, P-8 and WI-38 fibroblasts were exposed to fluorescent microspheres and subsequently stained by immunofluorescence for type I collagen. Many cells were seen both to contain fluorescent particles and to stain positively for type I collagen. These results indicate that marrow derived fibroblasts, in common with fibroblasts from other sources, have phagocytic capability under appropriate conditions.
Insights
Marrow-derived adherent cells (MDAC), primarily fibroblasts, exhibit phagocytic activity. These collagen-producing cells can engulf particles, demonstrating a previously unrecognized capability in fibroblast populations.
Area of Science:
- Cell Biology
- Connective Tissue Research
- Immunology
Background:
- Cultured marrow-derived adherent cells (MDAC) display phagocytic activity.
- MDAC populations are predominantly collagen-producing fibroblasts, lacking mononuclear phagocyte (MNP) markers.
- Previous characterization failed to identify Fc receptors on MDAC.
Purpose of the Study:
- To investigate the phagocytic activity of marrow-derived fibroblasts (MDAC).
- To determine if MDAC, confirmed as collagen-producing fibroblasts, possess phagocytic capabilities.
Main Methods:
- Characterization of MDAC for MNP markers and Fc receptors.
- In vitro phagocytosis assays using polystyrene microspheres.
- Immunofluorescence staining for type I collagen in phagocytic cells.
Main Results:
- MDAC confirmed to synthesize collagen and lack Fc receptors.
- Approximately 40% of MDAC demonstrated phagocytic activity against microspheres.
- Fibroblasts (MDAC, P-8, WI-38) containing fluorescent particles also stained positive for type I collagen.
Conclusions:
- Marrow-derived fibroblasts possess phagocytic capabilities under specific conditions.
- This phagocytic function is observed in fibroblasts from various sources, not exclusively MNP.
- Fibroblasts can perform phagocytosis while simultaneously producing collagen.