Key Points
- To determine whether endothelin-1 functions as a mitogen or drives phenotypic differentiation and cell cycle changes in vascular smooth muscle cells.
- Stimulated quiescent vascular smooth muscle cells (VSMCs) with peptide agonists to measure autocrine endothelin-1 (ET-1) secretion.
- Exposed VSMCs to ET-1 in nonmitogenic medium for 12–15 days to track cell cycle progression through S and G2/M phases.
- Assessed phenotypic maturation by measuring smooth muscle-specific alpha-actin expression following ET-1 treatment.
- Quiescent VSMCs secreted biologically active ET-1 in response to peptide stimulation, confirming an autocrine signaling capacity.
- Long-term ET-1 exposure in nonmitogenic conditions attenuated cell progression through S and G2/M phases and arrested the cell cycle at late G1/early S phase.
- VSMCs significantly upregulated smooth muscle-specific alpha-actin expression after prolonged ET-1 treatment, indicating induction of a differentiated contractile phenotype.
Structured PICO
PPopulationVascular smooth muscle cells (VSMCs)
IInterventionEndothelin-1 (ET-1) exposure for 12-15 days in nonmitogenic medium
OOutcomeCell cycle progression and phenotypic differentiation (smooth muscle-specific alpha-actin expression)surrogate
ET-1 may act as an autocrine factor that attenuates cell cycling and promotes phenotypic differentiation of vascular smooth muscle cells, contrary to its proposed role as a simple mitogen.