Impact of substrate stiffness on dermal papilla aggregates in microgels.

Interaction between cells and the extracellular environment plays a vital role in cellular development. The mechanical property of a 3-dimensional (3D) culture can be modified to mimic in vivo conditions. Dermal papilla (DP) cells are shown to gradually lose their inductivity in hair cycle development in a 2-dimensional culture. They are shown to partially restore their inductivity when transferred into a 3D microenvironment. In this study, a microarray fabricated from three different concentrations of poly-ethylene-glycol-diacrylate 3500, namely 5%, 10% and 15% w/v, yielded increasing substrate stiffness. The impact of varying substrate stiffness was tested for DP cell viability, attachment, and selected hair inductive markers. DP aggregates were shown to be viable and exhibited greater spreading with increasing substrate stiffness. Moreover, DP aggregates cultured on a softer substrate showed a greater fold change of gene and protein expressions than those cultured on a harder substrate.