Investigation of anti-cancer effects of new pyrazino[1,2-a]benzimidazole derivatives on human glioblastoma cells through 2D in vitro model and 3D-printed microfluidic device.

AIMS: Recent studies show targeted therapy of new pyrazino[1,2-a]benzimidazole derivatives with COX-II inhibitory effects on different cancer cells. This study aimed to investigate 2D cell culture and 3D spheroid formation of glioblastoma multiforme (GBM) cells using a microfluidic device after exposure to these compounds. MAIN METHODS: After isolating astrocytes from human GBM samples, IC50 of 2,6-dimethyl pyrazino[1,2-a]benzimidazole (L1) and 3,4,5-trimethoxy pyrazino[1,2-a]benzimidazole (L2) were determined as 13 µM and 85 µM, respectively. Then, in all experiments, cells were exposed to subtoxic concentrations of L1 (6.5 µM) and L2 (42.5 µM), which were ½IC50. In the following, in two phases, cell cycle, migration, and gene expression through 2D cell culture and tumor spheroid formation ability using a 3D-printed microfluidic chip were assessed. KEY FINDINGS: The obtained results showed that both compounds have positive effects in reducing G2/M cell population and GBM cell migration. Furthermore, real-time gene expression data showed that L1 and L2 significantly impact the upregulation of P21 and P53 and down-regulation of cyclin D1, MMP2, and MMP9. On the other hand, GBM spheroids exposed to L1 and L2 become smaller with fewer live cells. SIGNIFICANCE: Our data on human isolated astrocyte cells in 2D and 3D cell culture conditions showed that L1 and L2 compounds could reduce GBM cells' invasion by controlling gene expressions associated with migration and proliferation. Moreover, designing microfluidic platform and related cell culture protocols facilitates the broad screening of 3D multicellular tumor spheroids derived from GBM tumor biopsies and provides effective drug development for brain gliomas.

A combined 3D printing/CNC micro-milling method to fabricate a large-scale microfluidic device with the small size 3D architectures: an application for tumor spheroid production.

The fabrication of a large-scale microfluidic mold with 3D microstructures for manufacturing of the conical microwell chip using a combined projection micro-stereolithography (PµSL) 3D printing/CNC micro-milling method for tumor spheroid formation is presented. The PµSL technique is known as the most promising method of manufacturing microfluidic chips due to the possibility of creating complex three-dimensional microstructures with high resolution in the range of several micrometers. The purpose of applying the proposed method is to investigate the influence of microwell depths on the formation of tumor spheroids. In the conventional methods, the construction of three-dimensional microstructures and multi-height chips is difficult, time-consuming, and is performed using a multi-step lithography process. Microwell depth is an essential parameter for microwell design since it directly affects the shear stress of the fluid flow and the diffusion of nutrients, respiratory gases, and growth factors. In this study, a chip was made with microwells of different depth varying from 100 to 500 µm. The mold of the microwell section is printed by the lab-made PµSL printer with 6 and 1 µm lateral and vertical resolutions. Other parts of the mold, such as the main chamber and micro-channels, were manufactured using the CNC micro-milling method. Finally, different parts of the master mold were assembled and used for PDMS casting. The proposed technique drastically simplifies the fabrication and rapid prototyping of large-scale microfluidic devices with high-resolution microstructures by combining 3D printing with the CNC micro-milling method.