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Tractional force generation by porcine Müller cells: paracrine stimulation by retinal pigment epithelium
I Mamballikalathil1, C Mann, C Guidry
1Department of Ophthalmology, University of Alabama at Birmingham, 35294, USA.
Purpose:
To examine the ability of retinal pigment epithelial (RPE) cells to modulate Müller cell extracellular matrix contraction through secreted promoters.
Methods:
Freshly isolated RPE cells were maintained in continuous culture until the morphologic and immunocytochemical changes associated with myofibroblastic dedifferentiation were complete. Secretory products collected from these cells during extended incubations in serum-free medium and at different stages of dedifferentiation were examined for the ability to promote extracellular matrix contraction by Müller cells. The contributions of specific growth factors to RPE-secreted activity were examined with growth factor-neutralizing antibodies.
Results:
Secretory products from RPE cells throughout dedifferentiation contained biologically active quantities of Müller cell contraction promoters. Secretory activity increased during extended incubation in serum-free medium and during myofibroblastic dedifferentiation. Growth factor-specific neutralizing antibodies enabled the determination that insulin-like growth factor- and platelet-derived growth factor-related proteins were the secreted species to which Müller cells responded. Finally, gene expression of insulin-like growth factor 1 and platelet-derived growth factor A chain by porcine RPE cells was confirmed using reverse transcription-polymerase chain reaction. CONCLUSIONS. RPE cells are a viable source of biologically active quantities of two growth factors that stimulate extracellular matrix contraction by Müller cells. This secretory profile persists for extended periods in an otherwise serum-free environment and is enhanced during myofibroblastic dedifferentiation.
Insights
Retinal pigment epithelial (RPE) cells secrete factors that promote Müller cell extracellular matrix contraction. This activity increases with dedifferentiation and is mediated by insulin-like growth factor and platelet-derived growth factor.
Area of Science:
- Ophthalmology
- Cell Biology
- Biochemistry
Background:
- Retinal pigment epithelial (RPE) cells play crucial roles in retinal health.
- Müller cells contribute to the retinal extracellular matrix (ECM).
- Understanding cell-cell communication in the retina is vital for regenerative medicine.
Purpose of the Study:
- To investigate the capacity of RPE cells to influence Müller cell ECM contraction.
- To identify secreted factors from RPE cells that modulate Müller cell behavior.
Main Methods:
- RPE cells were cultured and observed through myofibroblastic dedifferentiation.
- Secretory products were collected and tested for ECM contraction-promoting activity on Müller cells.
- Growth factor-neutralizing antibodies and RT-PCR were used to identify specific factors.
Main Results:
- RPE cell secretions consistently promoted Müller cell ECM contraction.
- Secretory activity heightened with extended culture and dedifferentiation.
- Insulin-like growth factor (IGF) and platelet-derived growth factor (PDGF) were identified as key mediators.
Conclusions:
- RPE cells actively secrete IGF and PDGF, stimulating Müller cell ECM contraction.
- This RPE secretory function is sustained in serum-free conditions and amplified during dedifferentiation.
- These findings highlight a novel mechanism of RPE-Müller cell interaction with therapeutic implications.
