Quantitative analysis of the rheological properties of the cytoplasm of embryonic stem cells

GUBERMAN A; OSES C; ROMERO J.; LEVI V; ASPLANATO L; VERNERI P

Simposio; Escuela de invierno J. J. Giambiagi - Físicos en el mundo de la salud: un encuentro transdisciplinario.; 2018

Pluripotent stem cells (PSC) constitute an important promise for regenerativemedicine due to their capacity of self-renewal and differentiation into cells of allthree germinal layers - endoderm, mesoderm and ectoderm-.We investigate the rheological properties of the cytoplasm of undifferentiatedand differentiated PSC, particularly W4 mouse embryonic stem cells (ESC), totest their impact in mechanical communication and nuclei positioning. While itis known that the mechanical communication between nucleus and cytoplasmis a key process involved in both the positioning of the nucleus and its biologi-cal functions, it is believed that the cytoplasm?s rheological behaviour changesduring differentiation. Active forces in the cytoskeleton could be regulators ofchromatin?s organization and dynamics and thus, gene expression and cell differ-entiation, implying external mechanical signals may trigger cell differentiation.With this aim we run fluorescence correlation spectroscopy (FCS) experi-ments in the cytoplasm of W4 ESC expressing different tandems of the fluo-rescent protein EGFP -molecular tracers of different sizes- in order to studymultiple dynamics inside the cytoplasm.We have managed to successfully implement the culture conditions andtransfection protocol of the ESCs, as well as measure the diffusion and anoma-lous diffusion coefficient in vivo utilizing FCS, fitting the autocorrelation toan anomalous free diffusion. We hope that understanding the way these me-chanical external signals are transmitted to the nucleus could contribute to thecomprehension of a new side of cell differentiation.