Deconstructing the Effects of Matrix Elasticity and Geometry in Mesenchymal Stem Cell Lineage Commitment

Abstract

A wide variety of environmental factors including physical and biochemical signals are responsible for stem cell behavior and function. In particular, matrix elasticity and cell shape have been shown to determine stem cell function, yet little is known about the interplay between how these physical cues control cell differentiation. For the first time, by using ultraviolet (UV) lithography to pattern poly(ethylene) glycol (PEG) hydrogels we are able to manufacture microenvironments capable of parsing the effects of matrix elasticity, cell shape, and cell size in order to explore the relationship between matrix elasticity and cell shape in mesenchymal stem cell (MSC) lineage commitment. Our data shows that cells cultured on 1,000 μm2 circles, squares, and rectangles were primarily adipogenic lineage regardless of matrix elasticity, while cells cultured on 2,500 and 5,000 μm2 shapes more heavily depended on shape and elasticity for lineage specification. We further went on to characterize how modifying the cell cytoskeleton through pharmacological inhibitors can modify cell behavior. By showing MSC lineage commitment relationships due to physical signals, this study highlights the importance of cell shape and matrix elasticity in further understanding stem cell behavior for future tissue engineering strategies.

Nanostructured scaffold as a determinant of stem cell fate

“…Through the arrangement of adhesion epitopes available to the cell, the topographical features on the substrates such as grooves/pillars of micrometer to nanometer size are sensed by cells [89, 90]. The size of the adhesive area is the most significant physical signal to determine cell fate as it is mediated by the integrins [91]. The various integrin-mediated signaling mechanisms are described below.…”

Substrate topography: A valuable in vitro tool, but a clinical red herring for in vivo tenogenesis

“…Surface topography alone [20] or in combination with substrate rigidity [21] have been shown to control mesenchymal stem cell lineage commitment. Recently, multi-scale patterned substrates have been shown to control adhesion and differentiation of human mesenchymal stem cells [22] and topographical features combined with hyaluronic acid have been shown to enhance chondrogenic differentiation of dental pulp stem cells [23].…”

Elastic hydrogel substrate supports robust expansion of murine myoblasts and enhances their engraftment

“…The delivery of soluble factors to stem cells in culture has been the most extensively applied approach in efforts to stem cell fates [15,16]. However, in the past decade, more studies have investigated the effects of insoluble factors as well, and one such factor, substrate or matrix elasticity, was shown to have a remarkable influence on stem cell behavior [17][18][19][20][21][22].…”

“…As expected, myoblasts cultured for 20 passages on the elastic hydrogel surface exhibited robust regenerative capability in a series of experiments both in vitro and in vivo, implying the broad application potential of this hydrogel substrate in myoblast-based cellular therapies.The stem cell niche plays a very crucial role in the regulation of stem cell behavior and fate[12][13][14][15][16]. Among the numerous soluble and insoluble factors that constitute the stem cell niche, the importance of substrate elasticity has been recognized and highlighted by multiple studies[17][18][19][20][21][22][23]. By recapitulating the elasticity of muscle tissues, we aimed to create an appropriate microenvironment for in vitro propagation of myoblasts and investigated its influence specifically on cell proliferation, differentiation, gene expression, and in vivo engraftment.…”