Tracking the Mechanical Dynamics of Stem Cell Chromatin

Abstract

1030-Plat Tracking the Mechanical Dynamics of Stem Cell Chromatin Elizabeth Hinde 1 , Francesco Cardarelli 2 , Aaron Chen 3 , Michelle Khine 3 , Enrico Gratton 1 . Laboratory for Fluorescence Dynamics, University fo California, Irvine, CA, USA, 2 Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy, 3 University fo California, Irvine, CA, USA. A plastic chromatin structure has emerged as fundamental to the self-renewal and pluripotent capacity of embryonic stem (ES) cells. Direct measurement of chromatin dynamics in vivo is however challenging as high spatiotemporal resolution is required. Here we present a new tracking based method which can detect chromatin fiber movement and quantify the mechanical dynamics of chromatin in live cells. We use this method to study how the mechanical properties of chromatin movement in hESCs are modulated spatiotemporally during differentiation into cardiomyocytes (CM). Notably, we find that plurip- otency is associated with a highly discrete, energy-dependent frequency of chromatin movement, that we refer to as a ‘‘breathing’’ state. We find that this ‘‘breathing’’ state is strictly dependent on the metabolic state of the cell and is progressively silenced during differentiation, thus representing a hall- mark of pluripotency maintenance. This is a result that could not have been observed without the nanometer resolution provided by this novel tracking method.