Plug-and-Play In Vitro Metastasis System toward Recapitulating the Metastatic Cascade

Abstract

Microfluidic-based tumor models that mimic tumor culture environment have been developed to understand the cancer metastasis mechanism and discover effective antimetastatic drugs. These models successfully recapitulated key steps of metastatic cascades, yet still limited to few metastatic steps, operation difficulty, and small molecule absorption. In this study, we developed a metastasis system made of biocompatible and drug resistance plastics to recapitulate each metastasis stage in three-dimensional (3D) mono- and co-cultures formats, enabling the investigation of the metastatic responses of cancer cells (A549-GFP). The plug-and-play feature enhances the efficiency of the experimental setup and avoids initial culture failures. The results demonstrate that cancer cells tended to proliferate and migrate with circulating flow and intravasated across the porous membrane after a period of 3 d when they were treated with transforming growth factor-beta 1 (TGF-β1) or co-cultured with human pulmonary microvascular endothelial cells (HPMECs). The cells were also observed to detach and migrate into the circulating flow after a period of 20 d, indicating that they transformed into circulating tumor cells for the next metastasis stage. We envision this metastasis system can provide novel insights that would aid in fully understanding the entire mechanism of tumor invasion.

Development of a Novel Hanging Drop Platform for Engineering Controllable 3D Microenvironments

“…The ring structure of the upper part had 4.6 mm outer diameter and 1.2 mm inner diameter while the ring structure of the lower part had 4.6 mm outer diameter and 2.6 mm inner diameter (Supplementary Figure S1). Both parts were designed using the Solid Edge 2D software package (ST9, Siemens, United States) and fabricated using a layer-by-layer stacking technique on the PET sheets (Ni et al, 2019). The PET sheets were prelaminated with double-sided adhesive tape (9122, 3M Company, United States) and machined using a laser cutting machine (PLS6.75, Universal Laser System, United States) so that the holding layer could be assembled with the well plate to generate specialized geometries.…”

Nanotechnology‐Based Strategies to Evaluate and Counteract Cancer Metastasis and Neoangiogenesis

“…Tumor metastasis is a multistep process that includes local tumor cell detachment, intravasation, dissociation into the circulating blood vessels or lymphatic system, and extravasation into distal organs. [61,62] Main cancer treatments are generally based on cancer cell cytotoxicity induced by targeted drugs developed to clear or reduce the size of solid tumors, [63] while the underestimation of tumor invasion/metastasis phenomena and the misadministration of antimetastatic drugs dramatically decrease the success rate in cancer fighting. [64]…”

“…Moreover, the high sensitivity of this method provides an opportunity to analyze a small volume of samples and a low number of cells; this is particularly useful in evaluating rare primary cell populations obtained by biopsy. [62] In another type of microfluidic-based assays, named the onchip cell migration assay, the fluidic channel is partially separated into several small channels to allow different fluidic solution to flow at the same time (Figure 3d). [92] As an alternative wound generating system, confluent cultured cells are exposed to different fluids flowing inside small channels; since trypsin/EDTA solution flows from some of the channels, the cells are detached and leave a cell-free area.…”

“…[ 91 ] In the plug and play microfluidic‐based assays, the U‐well is allowed to be inserted directly into the metastasis chip housing the complete cell culture in flow conditions. [ 62 ] The cells in the first chamber are separated from the channel with a microfilter in the U‐well, which differs from other methods that provide a barrier effect against cell migration in the direction of a chemotactic agent across the filter. This system also reduces the experimental setup time and avoids initial culture failures during the cell seeding process compared to other existing microfluidic metastasis chips.…”

“…Moreover, the high sensitivity of this method provides an opportunity to analyze a small volume of samples and a low number of cells; this is particularly useful in evaluating rare primary cell populations obtained by biopsy. [ 62 ]…”