A Facile and Scalable Hydrogel Patterning Method for Microfluidic 3D Cell Culture and Spheroid-in-Gel Culture Array.

Chengxun Su,Han Wei Hou,Hui Min Tay,Rinkoo Dalan,Hong Boon Ong,Yon Jin Chuah

doi:10.3390/bios11120509

Chengxun Su, Han Wei Hou + Show 4 more

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https://doi.org/10.3390/bios11120509

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Abstract

Incorporation of extracellular matrix (ECM) and hydrogel in microfluidic 3D cell culture platforms is important to create a physiological microenvironment for cell morphogenesis and to establish 3D co-culture models by hydrogel compartmentalization. Here, we describe a simple and scalable ECM patterning method for microfluidic cell cultures by achieving hydrogel confinement due to the geometrical expansion of channel heights (stepped height features) and capillary burst valve (CBV) effects. We first demonstrate a sequential “pillar-free” hydrogel patterning to form adjacent hydrogel lanes in enclosed microfluidic devices, which can be further multiplexed with one to two stepped height features. Next, we developed a novel “spheroid-in-gel” culture device that integrates (1) an on-chip hanging drop spheroid culture and (2) a single “press-on” hydrogel confinement step for rapid ECM patterning in an open-channel microarray format. The initial formation of breast cancer (MCF-7) spheroids was achieved by hanging a drop culture on a patterned polydimethylsiloxane (PDMS) substrate. Single spheroids were then directly encapsulated on-chip in individual hydrogel islands at the same positions, thus, eliminating any manual spheroid handling and transferring steps. As a proof-of-concept to perform a spheroid co-culture, endothelial cell layer (HUVEC) was formed surrounding the spheroid-containing ECM region for drug testing studies. Overall, this developed stepped height-based hydrogel patterning method is simple to use in either enclosed microchannels or open surfaces and can be readily adapted for in-gel cultures of larger 3D cellular spheroids or microtissues.

Highlights

The overall success rate for phase I to phase III clinical trials is estimated to be 13.8%, and can be as low as 3.4% for oncology medication [1]
With a two-layered PDMS device and a stepped height feature at the intersection of a hydrogel channel and fluidic channel, the extracellular matrix (ECM) introduced at the bottom layer is confined at the stepped height owing to the capillary burst valve (CBV) effect conferred by the sudden channel expansion along the Z-axis
We propose that a single stepped height feature will be required for odd number of hydrogel lanes, while two stepped height features are needed for an even number of hydrogel lanes in a microfluidic design with fluidic channels at both sides (Figure 1D)

Summary

Introduction

The overall success rate for phase I to phase III clinical trials is estimated to be 13.8%, and can be as low as 3.4% for oncology medication [1] This translational failure is largely due to the reliance on in vivo animal testing and the lack of preclinical in vitro model that can accurately predict the drug responses in humans [2,3,4,5,6,7]. Spheroids offer higher biological complexity in terms of structural and functional properties by recapitulating the cell–cell interaction and tissuelike architecture [9,12] They are typically cultured in suspension (e.g., the hanging drop method or round bottom 96-well plate), and lack a surrounding extracellular matrix (ECM), which plays a vital role in mediating instructive signals for cell polarization, retention, and mobilization [4,13,14]. On the other hand, microengineered organ-on-a-chip systems have been widely used to reconstitute key functional unit of human organs by precisely manipulating the fluid flow and control of 3D tissue structure and ECM microenvironments [5,10,11,15]

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