Localized Induction of Gene Expression in Embryonic Stem Cell Aggregates Using Holographic Optical Tweezers to Create Bi
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Localized Induction of Gene Expression in Embryonic Stem Cell Aggregates Using Holographic Optical Tweezers to Create Biochemical Gradients Glen R Kirkham 1 & James Ware 2 & Thomas Upton 2 & Stephanie Allen 2 & Kevin M Shakesheff 2 & Lee DK Buttery 2 Received: 19 December 2018 / Revised: 17 April 2019 / Accepted: 8 June 2019 # The Author(s) 2019
Abstract Three-dimensional (3D) cell models that mimic the structure and function of native tissues are enabling more detailed study of physiological and pathological mechanisms in vitro. We have previously demonstrated the ability to build and manipulate 3D multicellular microscopic structures using holographic optical tweezers (HOTs). Here, we show the construction of a precisely patterned 3D microenvironment and biochemical gradient model consisting of mouse embryoid bodies (mEBs) and polymer microparticles loaded with retinoic acid (RA), embedded in a hydrogel. We demonstrate discrete, zonal expression of the RAinducible protein Stra8 within mEBs in response to release of RA from polymer microparticles, corresponding directly to the defined 3D positioning of the microparticles using HOTs. These results demonstrate the ability of this technology to create chemical microgradients at definable length scales and to elicit, with fidelity and precision, specific biological responses. This technique can be used in the study of in vitro microenvironments to enable new insights on 3D cell models, their cellular assembly, and the delivery of drug or biochemical molecules for engineering and interrogation of functional and morphogenic responses. Keywords Stem cells . Embryonic stem cells . In vitro model . Optical tweezers . Stra 8 . Retinoic acid . Embryoid bodies . HOTs
Introduction Our ability to understand the complex biology and physiology of cells and tissues is being advanced through innovative approaches to reproduce their multicellular three-dimensional (3D) interactions, structure, and function in vitro. With the relatively simple approach of culturing different cell types, together with specific signaling factors and natural or synthetic scaffolds, cells can be encouraged to self-assemble and form organized 3D cellular structures in vitro that mimic native tissues. Organoids and organ-on-chip technologies are now enabling investigation of specific developmental, Electronic supplementary material The online version of this article (https://doi.org/10.1007/s40883-019-00114-5) contains supplementary material, which is available to authorized users. * Lee DK Buttery [email protected] 1
College of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, UK
2
School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK
physiological, and disease processes and to dissect the effects and mechanisms of biochemical factors or drug molecules in a controlled manner [1–8]. The level of precision and accuracy of control of cell interactions and delivery of bio-instructive signals that can be achieved is varied among these technologies, and th
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