A microfluidic chip with a U-shaped microstructure array for multicellular spheroid formation, culturing and analysis

Abstract

Multicellular spheroids (MCS), formed by self-assembly of single cells, are commonly used as a three-dimensional cell culture model to bridge the gap between in vitro monolayer culture and in vivo tissues. However, current methods for MCS generation and analysis still suffer drawbacks such as being labor-intensive and of poor controllability, and are not suitable for high-throughput applications. This study demonstrates a novel microfluidic chip to facilitate MCS formation, culturing and analysis. The chip contains an array of U-shaped microstructures fabricated by photopolymerizing the poly(ethylene glycol) diacrylate hydrogel through defining the ultraviolet light exposure pattern with a photomask. The geometry of the U-shaped microstructures allowed trapping cells into the pocket through the actions of fluid flow and the force of gravity. The hydrogel is non-adherent for cells, promoting the formation of MCS. Its permselective property also facilitates exchange of nutrients and waste for MCS, while providing protection of MCS from shearing stress during the medium perfusion. Heterotypic MCS can be formed easily by manipulating the cell trapping steps. Subsequent drug susceptibility analysis and long-term culture could also be achieved within the same chip. This MCS formation and culture platform can be used as a micro-scale bioreactor and applied in many cell biology and drug testing studies.

Tumour-on-a-chip: microfluidic models of tumour morphology, growth and microenvironment

“…Three-dimensional spheroids can also be formed by assembly of cells using bio-orthogonal chemistry [54] or incubation of cells with magnetic particles [55,56] (figure 2g,h). Recently, several microfluidic techniques have been developed to create tumour spheroids by either hydrodynamic trapping of cells in stagnation regions or in microwell structures [57][58][59][60], aggregating multiple cells in double-emulsions or hydrogel droplets [61][62][63][64], or aggregating cells on a digital microfluidic platform [65] (figure 2i). The advantages of generating spheroids by microfluidics include control over spheroid size with continuous perfusion, as well as real time and in situ observation of spheroid formation kinetics.…”

Inventions and Innovations in Preclinical Platforms for Cancer Research

“…Microwells [8,25,[87][88][89] and U-shaped microstructures [21,64,[90][91][92][93] have been designed for spheroid formation and culture in microfluidic platforms. These structures facilitate short-term [23,94], controllable and uniform diameter [22,95] and compact spheroid generation [32,92].…”

“…These structures facilitate short-term [23,94], controllable and uniform diameter [22,95] and compact spheroid generation [32,92]. U-shaped microstructures either are actuated temporarily using pneumatics [91][92][93]96] or are fixed within the device [90,93]. A large number of these U-shaped microstructures were embedded (e.g., 360 [92], 28 [64], 512 [97]) in each microchamber of the µSFC to trap the cells [64,90,92,93,96] or the cell dispensed hydrogel droplets [64] introduced into the chip.…”

“…U-shaped microstructures either are actuated temporarily using pneumatics [91][92][93]96] or are fixed within the device [90,93]. A large number of these U-shaped microstructures were embedded (e.g., 360 [92], 28 [64], 512 [97]) in each microchamber of the µSFC to trap the cells [64,90,92,93,96] or the cell dispensed hydrogel droplets [64] introduced into the chip. Spheroid diameter is confined to the microstructure size and the relative position of the microstructures is essential for efficient cell trapping.…”

On-chip pressure sensor using single-layer concentric chambers

“…For example, the proposed sensor can be implemented in microfluidic culture environment for monitoring the pressure condition during the culture. 21 No alignment between layers for chip fabrication is needed, and a high success rate of chip fabrication is expected. The additional cost for implementing the sensor is the sensing fluid which is less than 1 USD for the editable color, as the one used in this paper.…”