Cellular Response to Heterogeneously Charged Polystyrene

Abstract

AbstractCells are sensitive to topological, chemical and electrical properties of substrates on which they are grown. However, most studies of cell-surface interactions have neglected electrical effects or confounded them with other substrate properties. The use of nanofabrication technology has made it possible to fabricate optically transparent surfaces, with controlled chemistry and topology, with active, controllable surface charge density in domains as small as 1–4 um1. Human monocytes incubated on polystyrene with 3.3 um wide strip domains alternately charged, so as to maintain overall charge neutrality, show significant charge density and time dependent increases (greater than twofold) in cell area and cell perimeter after challenge with a phagocytic trigger (human IgG opsonized Zymosan particles). Additional ultrastructural studies on silicon dioxide substrates show charge density dependent qualitative morphological differences. The human monocytes exhibited significant charge density and time dependent hyper-phagocytosis (> 25fold increase over control) of human IgG opsonized Zymosan particles. The charge-induced surfaces modulated the amplitude of the secreted extracellular levels of cytokines and also induced a temporal shift in the kinetics of cytokine release2.These studies demonstrate that human blood peripheral monocytes respond in-vitro to the peak magnitude of local surface charge heterogeneity in the absence of substrate topology and compositional variation.