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Activated human mononuclear phagocytes release a substance(s) that induces replication of quiescent human fibroblasts
Abstract:
Human mononuclear phagocytes (HMP) treated in vitro with N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) released a soluble substance(s) that induced in vitro replication of subconfluent, quiescent, serum-free human fibroblasts. The response was enhanced if nonmitogenic plasma-derived serum (PDS) was added to the HMP-conditioned media after harvest. The capacity of serum-free, quiescent fibroblasts to respond to the HMP-released substance(s) diminished with time in culture. The diminished proliferative response was reversed by adding PDS to the MDP-HMP-conditioned media. Similar results were obtained in parallel experiments using platelet-derived growth factor (PDGF). These data suggest that the HMP-associated growth-promoting substances may, like PDGF, act co-ordinately with substances in PDS to stimulate the proliferation of cells in vitro.
Insights
Human mononuclear phagocytes (HMP) treated with N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) release substances that stimulate fibroblast replication. This growth promotion is enhanced by plasma-derived serum (PDS) and resembles platelet-derived growth factor (PDGF) activity.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- Human mononuclear phagocytes (HMP) play roles in immune responses and tissue repair.
- Fibroblast proliferation is crucial for wound healing and tissue regeneration.
- Growth factors regulate cell division and differentiation.
Purpose of the Study:
- To investigate the role of HMP-conditioned media in stimulating fibroblast proliferation.
- To determine the effect of plasma-derived serum (PDS) on HMP-induced fibroblast growth.
- To compare the growth-promoting activity of HMP-released substances with platelet-derived growth factor (PDGF).
Main Methods:
- Human mononuclear phagocytes (HMP) were treated in vitro with N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP).
- Conditioned media from HMP cultures were used to treat quiescent, serum-free human fibroblasts.
- The effects of plasma-derived serum (PDS) and platelet-derived growth factor (PDGF) were assessed on fibroblast proliferation.
Main Results:
- MDP-treated HMP released soluble substances that induced in vitro replication of human fibroblasts.
- The fibroblast proliferative response was enhanced by the addition of nonmitogenic plasma-derived serum (PDS).
- The diminished proliferative capacity of aged fibroblasts was reversed by PDS, similar to PDGF effects.
Conclusions:
- HMP-associated growth-promoting substances can stimulate fibroblast proliferation in vitro.
- These HMP-derived factors may act synergistically with PDS components, akin to PDGF.
- This suggests a potential role for HMP in regulating tissue repair and growth through secreted factors.