Equibiaxial and uniaxial cyclic strain similarly affect Notch signaling and vascular smooth muscle cell phenotype in 2D

Vascular smooth muscle cells (VSMCs) play a crucial role in vascular growth and remodeling by adapting their phenotype in response to biomechanical cues. The Notch signaling pathway, known for its sensitivity to mechanical forces, is a regulator of strain-induced phenotypic plasticity of VSMCs. However, the impact of the intricate mechanical environment within the vessel wall on Notch signaling and VSMCs is not completely elucidated. In this study, we investigated the influence of strain anisotropy, which is important for understanding (patho)physiological mechanical conditions, on mechanosensitive Notch signaling and subsequent changes in VSMC phenotype. Using varying amplitudes of cyclic strain in the physiological range, we examined the effects of equibiaxial and uniaxial strain on Notch signaling and phenotypic transitions in synthetic and contractile VSMCs. Additionally, we compared cell responses between equibiaxial and uniaxial loading conditions by analyzing three different deformation characteristics to determine the primary strain measure governing Notch signaling and VSMC phenotype. Our findings reveal that both cyclic equibiaxial and uniaxial strain downregulate Notch signaling and contractile characteristics of VSMCs. Notably, these reductions are most similar for both loading conditions when the maximum principal strain values were compared. Overall, our results suggest that VSMCs respond in a comparable manner to equibiaxial and uniaxial strain, indicating that strain anisotropy may not significantly influence Notch signaling or phenotypic switching of VSMCs. 

Insight Box: Vascular smooth muscle cells (VSMCs) adapt their phenotype during vascular growth and remodeling in response to mechanical cues. The Notch signaling pathway, sensitive to mechanical stimuli, regulates this phenotypic plasticity. However, the effect of strain anisotropy, which is important for understanding (patho)physiological mechanical conditions, on Notch signaling and subsequent changes in VSMC phenotype is not clear. Understanding this relationship is crucial to determine how VSMC phenotype, contributing to vascular growth and remodeling, is regulated in physiological and pathological hemodynamic environments. Here, we showed that both equibiaxial and uniaxial strain downregulate Notch signaling components and the contractile properties of VSMCs. Our findings further highlighted the maximum principal strain as the dominant mechanical parameter influencing Notch signaling and VSMC phenotypic changes.