Temporal Transition of Mechanical Characteristics of HUVEC/MSC Spheroids Using a Microfluidic Chip with Force Sensor Probes

Abstract

Abstract:In this paper, we focus on the mechanical characterization of co-cultured spheroids of human umbilical vein endothelial cells (HUVECs) and mesenchymal stem cells (MSC) (HUVEC/MSC spheroids). HUVEC/MSC spheroids aggregate during culture, thereby decreasing in size. Since this size decrease can be caused by the contractility generated by the actomyosin of MSCs, which are intracellular frames, we can expect that there is a temporal transition for the mechanical characteristics, such as stiffness, during culture. To measure the mechanical characteristics, we use a microfluidic chip that is integrated with force sensor probes. We show the details of the measurement configuration and the results of mechanical characterization of the HUVEC/MSC spheroids. To evaluate the stiffness of the spheroids, we introduce the stiffness index, which essentially shows a spring constant per unit size of the spheroid at a certain time during measurement. From the measurement results, we confirmed that the stiffness index firstly increased during the days of culture, although after four days of culture, the stiffness index decreased. We confirmed that the proposed system can measure the stiffness of HUVEC/MSC spheroids.

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“…In contrast, HUVEC and HUVEC/HeLa co-culture spheroids became significantly more disturbed in their shape. This can be explained by HUVEC cells, showing a lower tendency to self-aggregate, further HUVEC spheroids are slower to form strong intercellular connections than HeLa and Ovarian cells 39 . Despite these morphological deformations, all spheroids preserve their 3D characteristics as shown by confocal z-stack microscopy (Supplemental Figure 1 ).…”

Faculty Opinions recommendation of Modeling Steatohepatitis in Humans with Pluripotent Stem Cell-Derived Organoids.

“…Interestingly, extensive fibrosis of organoids leads to stiffness increase per organoid that can be measured by AFM. Given that non-invasive elastography to measure liver stiffness has become increasingly standard for making decisions in clinical management of NASH patients (Kwok et al, 2016;Yoneda et al, 2008), these stiffness readout assays, coupled I with a higher throughput system such as on-chip platform (Ito et al, 2016), will be attractive to investigate human fibrosis associated with steatohepatitis. More broadly, our novel strategy paves the way for the precise investigation of patient-specific inflammatory mechanisms and the discovery of protective or effective treatments using diseased human liver organoids.…”

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