Synergistic Effects of Matrix Nanotopography and Stiffness on Vascular Smooth Muscle Cell Function

Abstract

Vascular smooth muscle cells (vSMCs) retain the ability to undergo modulation in their phenotypic continuum, ranging from a mature contractile state to a proliferative, secretory state. vSMC differentiation is modulated by a complex array of microenvironmental cues, which include the biochemical milieu of the cells and the architecture and stiffness of the extracellular matrix. In this study, we demonstrate that by using UV-assisted capillary force lithography (CFL) to engineer a polyurethane substratum of defined nanotopography and stiffness, we can facilitate the differentiation of cultured vSMCs, reduce their inflammatory signature, and potentially promote the optimal functioning of the vSMC contractile and cytoskeletal machinery. Specifically, we found that the combination of medial tissue-like stiffness (11 MPa) and anisotropic nanotopography (ridge width_groove width_ridge height of 800_800_600 nm) resulted in significant upregulation of calponin, desmin, and smoothelin, in addition to the downregulation of intercellular adhesion molecule-1, tissue factor, interleukin-6, and monocyte chemoattractant protein-1. Further, our results allude to the mechanistic role of the RhoA/ROCK pathway and caveolin-1 in altered cellular mechanotransduction pathways via differential matrix nanotopography and stiffness. Notably, the nanopatterning of the stiffer substrata (1.1 GPa) resulted in the significant upregulation of RhoA, ROCK1, and ROCK2. This indicates that nanopatterning an 800_800_600 nm pattern on a stiff substratum may trigger the mechanical plasticity of vSMCs resulting in a hypercontractile vSMC phenotype, as observed in diabetes or hypertension. Given that matrix stiffness is an independent risk factor for cardiovascular disease and that CFL can create different matrix nanotopographic patterns with high pattern fidelity, we are poised to create a combinatorial library of arterial test beds, whether they are healthy, diseased, injured, or aged. Such high-throughput testing environments will pave the way for the evolution of the next generation of vascular scaffolds that can effectively crosstalk with the scaffold microenvironment and result in improved clinical outcomes.

Valve interstitial cell contractile strength and metabolic state are dependent on its shape

“…While several other methods exist wherein cellular shape and structure could be modulated while maintaining cell-cell contact, 11b, c, 23 our single cell model represents the smallest functional unit of the VIC and thus an important first step in understanding the role of VIC shape on its biology and function. Shorter and wider VICs generated less contractile stress and were at a less biosynthetic and proliferative state, while elongated narrower VICs had greater contractile stress generation, more biosynthesis, increased proliferation and α-SMA activation, correlating with greater organization of the actin cytoskeleton.…”

Combined Effects of Substrate Topography and Stiffness on Endothelial Cytokine and Chemokine Secretion

“…12,22 A small amount of polymer was drop-dispensed onto a glass coverslip (No.1, 25mm, Fisher Scientific, Pittsburgh, PA, USA), and a PUA nanopattern mold on PET film was placed onto the polymer drop. The polymer spontaneously filled the cavity of the mold through capillary action.…”

“…8-11 Recent studies have suggested that nanotopographic cues and substrate rigidities are important factors affecting the morphology and behavior of vascular cell types, including endothelial cells. 7,12-14 …”

Electroconductive Nanopatterned Substrates for Enhanced Myogenic Differentiation and Maturation

“…[60, 61] Briefly, polymer master molds were created by first dispensing PUA precursor solution onto a patterned silicon wafer that was generated using standard photolithography. A nanopattern comprising a series of parallel ridges and grooves with 800 nm × 800 nm × 600 nm (ridge width × groove width × ridge height) dimensions was used for these studies.…”