Investigation of Drug Cocktail Effects on Cancer Cell-Spheroids Using a Microfluidic Drug-Screening Assay

The impact of microfluidics in high-throughput drug-screening applications

Drug discovery is an expensive and lengthy process. Among the different phases, drug discovery and preclinical trials play an important role as only 5-10 of all drugs that begin preclinical tests proceed to clinical trials. Indeed, current high-throughput screening technologies are very expensive, as they are unable to dispense small liquid volumes in an accurate and quick way. Moreover, despite being simple and fast, drug screening assays are usually performed under static conditions, thus failing to recapitulate tissue-specific architecture and biomechanical cues present in vivo even in the case of 3D models. On the contrary, microfluidics might offer a more rapid and cost-effective alternative. Although considered incompatible with high-throughput systems for years, technological advancements have demonstrated how this gap is rapidly reducing. In this Review, we want to further outline the role of microfluidics in high-throughput drug screening applications by looking at the multiple strategies for cell seeding, compartmentalization, continuous flow, stimuli administration (e.g., drug gradients or shear stresses), and single-cell analyses.

A novel design of microfluidic platform for metronomic combinatorial chemotherapy drug screening based on 3D tumor spheroid model

For treating cancer at various stages, chemotherapy drugs administered in combination provide better treatment results with lower side effects compared to single-drug therapy. However, finding the potential drug combinations has been challenging due to the large numbers of possible combinations from approved drugs and the failure of in vitro 2D well plate-based cancer models. 3D spheroid-based high-throughput microfluidic platforms recapitulate some of the important features of native tumor tissue and offer a promising alternative to evaluate the combinatory effects of the drugs. This study develops a novel polydimethylsiloxane (PDMS) based microfluidic design with a dynamic environment and strategically placed U-shaped wells for testing all seven possible combinations (three single-drug treatments, three pairwise combinations, treatment with all three drugs) of three chemotherapy drugs (Paclitaxel, Vinorelbine, and Etoposide) on lung tumor spheroids. The design of U-shaped wells has been validated with computational results. Firstly, we test all combinations of drugs on the conventional well plate in static conditions with 3D tumor spheroids. Based on static drug testing results, we show a proof-of-concept by testing the most effective drug combination on the microfluidic device in a dynamic environment. The concentration of the drugs used in combination falls below the maximum tolerated dose (MTD) of the individual drugs, towards low dose metronomic (LDM) chemotherapy. LDM combinatorial chemotherapy identified in this study can potentially lower toxicity and provide better treatment results in cancer patients. The device can be further used to culture patient-specific tumor spheroids and identify synergistic drug combinations for personalized medicine.

Fabrication approaches for high-throughput and biomimetic disease modeling

There is often a tradeoff between in vitro disease modeling platforms that capture pathophysiologic complexity and those that are amenable to high-throughput fabrication and analysis. However, this divide is closing through the application of a handful of fabrication approaches-parallel fabrication, automation, and flow-driven assembly-to design sophisticated cellular and biomaterial systems. The purpose of this review is to highlight methods for the fabrication of high-throughput biomaterial-based platforms and showcase examples that demonstrate their utility over a range of throughput and complexity. We conclude with a discussion of future considerations for the continued development of higher-throughput in vitro platforms that capture the appropriate level of biological complexity for the desired application. STATEMENT OF SIGNIFICANCE: There is a pressing need for new biomedical tools to study and understand disease. These platforms should mimic the complex properties of the body while also permitting investigation of many combinations of cells, extracellular cues, and/or therapeutics in high-throughput. This review summarizes emerging strategies to fabricate biomimetic disease models that bridge the gap between complex tissue-mimicking microenvironments and high-throughput screens for personalized medicine.

Construction of cancer-on-a-chip for drug screening

Cancer-on-a-chip has effectively contributed to the development of drug screening, holding great promise for more convenient and reliable drug development as well as personalized drug administration.

A numerical study on tumor-on-chip performance and its optimization for nanodrug-based combination therapy

Microfluidic devices, such as the tumor-on-a-chip (ToC), allow for the delivery of multiple drugs as desired for various therapies such as cancer treatment. Due to the complexity involved, visualizing, and gaining knowledge of the performance of such devices through experimentation alone is difficult if not impossible. In this paper, we performed a numerical simulation study on ToC performance, which focuses on the ability to combine multiple nanodrugs and optimized ToC performance. The numerical simulations of the chip performance were performed based on the typical chip design and operating parameters, as well as the established governing equations, boundary conditions, and fluid-structure interaction. The effect of cell injection time and position, inlet flow rate, number of inlets, medium viscosity, and cell concentration on the chip performance in terms of shear stress and cell distribution were examined. The results illustrate the profound effect of operation parameters, thus allowing for rigorously determining operational parameters to prevent spheroids ejection from microwells and to restrict the shear stresses within a physiological range. Also, the results show that triple-inlets can increase the uniformity of cell distribution in comparison with single or double inlets. Based on the simulation results, the architecture of the primary ToC was further optimized, resulting in a novel design that enables applying multiple, yet simultaneous, nanodrugs with optimal drug combination as desired for an individual patient. Furthermore, our simulations on the optimized chip showed a uniform cell distribution required for uniform-sized tumor spheroids generation, and complete medium exchange. Taken together, this study not only illustrates that numerical simulations are effective to visualize the ToCs performance, but also develops a novel ToC design optimized for nanodrug-based combination therapy.

Effects of novel somatostatin-dopamine chimeric drugs in 2D and 3D cell culture models of neuroendocrine tumors

Control of symptoms related to hormonal hypersecretion by functioning neuroendocrine tumors (NETs) is challenging. New therapeutic options are required. Since novel in vitro tumor models seem to better mimic the tumor in vivo conditions, we aimed to study the effect of somatostatin and dopamine receptor agonists (octreotide and cabergoline, respectively) and novel somatostatin-dopamine chimeric multi-receptor drugs (BIM-065, BIM-23A760) using 2D (monolayer) and 3D (spheroids) cultures. Dose-response studies in 2D and 3D human pancreatic NET cell cultures (BON-1 and QGP-1) were performed under serum-containing and serum-deprived conditions. Cell proliferation, somatostatin and dopamine receptor expression (SSTs and D2R), apoptosis, lactate dehydrogenase, as well as serotonin and chromogranin A (CgA) release were assessed. The following results were obtained. 3D cultures of BON-1/QGP-1 allowed better cell survival than 2D cultures in serum-deprived conditions. SSTs and D2R mRNA levels were higher in the 3D model vs 2D model. Octreotide/cabergoline/BIM-065/BIM-23A760 treatment did not affect cell growth or spheroid size. In BON-1 2D-cultures, only BIM-23A760 significantly inhibited CgA release -this effect being more pronounced in 3D cultures. In BON-1 2D cultures, cabergoline/BIM-065/BIM-23A760 treatment decreased serotonin release (maximal effect up to 40%), being this effect again more potent in 3D cultures (up to 67% inhibition; with BIM-23A760 having the most potent effects). In QGP-1, cabergoline/BIM-065 treatment decreased serotonin release only in the 3D model. In conclusion, cultures of NET 3D spheroids represent a promising method for evaluating cell proliferation and secretion in NET cell-line models. Compared to 2D models, 3D models grow relatively serum independent. In 3D model, SST-D2R multi-receptor targeting drugs inhibit CgA and serotonin secretion, but not NET cell growth.

Formation of size-controllable tumour spheroids using a microfluidic pillar array (μFPA) device

We describe a method to generate several hundreds of spheroids using a microfluidic device with pillars.

The Continuous Concentration of Particles and Cancer Cell Line Using Cell Margination in a Groove-Based Channel

In the capillary venules, blood cells auto-separate with red blood cells aggregating near the centre of vessel and the nucleated cells marginating toward the wall of vessel. In this experiment, we used cell margination to help enrich the Jurkat cells via a groove-based channel which provides a vertical expansion-contraction structure, wherein the red blood cells invade the grooves and push the Jurkat cells to the bottom of the channel. The secondary flows induced by the anisotropic grooves bring the Jurkat cells to the right sidewall. Rigid, 13-µm diameter polystyrene particles were spiked into the whole blood to verify the operating principle under various working conditions, and then tests were carried out using Jurkat cells (~15 µm). The performance of this device was quantified by analysing the cell distribution in a transverse direction at the outlet, and then measuring the cell concentration from the corresponding outlets. The results indicate that Jurkat cells were enriched by 22.3-fold with a recovery rate of 83.4%, thus proving that this microfluidic platform provides a gentle and passive way to isolate intact and viable Jurkat cells.