Engineering microscale topographies to control the cell-substrate interface

a b s t r a c t Cells in their in vivo microenvironment constantly encounter and respond to a multitude of signals. While the role of biochemical signals has long been appreciated, the importance of biophysical signals has only recently been investigated. Biophysical cues are presented in different forms including topography and mechanical stiffness imparted by the extracellular matrix and adjoining cells. Microfabrication technologies have allowed for the generation of biomaterials with microscale topographies to study the effect of biophysical cues on cellular function at the cellesubstrate interface. Topographies of different geometries and with varying microscale dimensions have been used to better understand cell adhesion, migration, and differentiation at the cellular and sub-cellular scales. Furthermore, quantification of cellgenerated forces has been illustrated with micropillar topographies to shed light on the process of mechanotransduction. In this review, we highlight recent advances made in these areas and how they have been utilized for neural, cardiac, and musculoskeletal tissue engineering application

Embryoid body size-mediated differential endodermal and mesodermal differentiation using polyethylene glycol (PEG) microwell array

Embryoid bodies have a number of similarities with cells in gastrulation, which provides useful biological information about embryonic stem cell differentiation. Extensive research has been done to study the control of embryoid body-mediated embryonic stem cell differentiation in various research fields. Recently, microengineering technology has been used to control the size of embryoid bodies and to direct lineage specific differentiation of embryonic stem cells. However, the underlying biology of developmental events in the embryoid bodies of different sizes has not been well elucidated. In this study, embryoid bodies with different sizes were generated within microfabricated PEG microwell arrays, and a series of gene and molecular expressions related to early developmental events was investigated to further elucidate the size-mediated differentiation. The gene and molecular expression profile suggested preferential visceral endoderm formation in 450 μm embryoid bodies and preferential lateral plate mesoderm formation in 150 μm embryoid bodies. These aggregates resulted in higher cardiac differentiation in 450 μm embryoid bodies and higher endothelial differentiation in 150 μm embryoid bodies, respectively. Our findings may provide further insight for understanding embryoid body size-mediated developmental progress.National Science Foundation (U.S.) (CAREER Award DMR0847287)United States. Office of Naval Research (Naval Research Young National Investigator Award)National Institutes of Health (U.S.) (HL092836, EB02597, AR057837