Pumpless, unidirectional microphysiological system for testing metabolism-dependent chemotherapeutic toxicity

A pump-free microfluidic co-culture system for investigating NK cell-tumor spheroid interactions in flow conditions

Natural killer (NK) cells are pivotal in immunotherapy due to their potent tumor-targeting capabilities. However, accessible in vitro 3D dynamic models for evaluating Tumor Infiltrating Natural Killer Cells (TINKs) remain scarce. This study addresses this gap by developing a novel pump-free microfluidic chip to investigate the interactions between NK-92 cells and prostate DU 145 tumor spheroids. The platform facilitates the separation of free NKs and TINKs for subtype characterization. The design integrates multiple planes with a multi-layer paper scaffold to accommodate tumor spheroids, allowing NK-92 cells to traverse Matrigel-coated barriers that mimic the extracellular matrix. The dual-channel pump-free device enables unidirectional circulation of NK-92 cells, allowing analysis of tumor spheroid movement and NK-92 cell interactions under flow conditions. Results demonstrate continuous fluid circulation in the dual-channel device by rocking the platform at tilt angles of 21° and 15°. Tumor spheroids show- enhanced migration under flow conditions compared to static culture. Although spheroids recruit slightly more NK-92 cells under flow conditions, CD56 and CD16 receptor expression on IL-2-activated free NK-92 cells and tumor-infiltrating NK-92 cells matches in vivo patterns in dynamic cultures. These findings suggest that tumor cells and fluid dynamics significantly influence NK cell subtypes. This pump-free microfluidic platform is a functional tool for simulating and studying immune cell-tumor interactions, providing valuable insights into NK cell dynamics with tumor spheroids in physiologically relevant environments.

Development of a Microphysiological System to Model Human Cancer Metastasis From the Colon to the Liver

We describe a novel device to mimic the metastasis of cancer cells from the colon into the liver in a human model. The colon mimic is connected to the liver model by a gravity-driven recirculating unidirectional flow of a blood surrogate and can mimic the five steps of the metastatic cascade: invasion in the colon, intravasation into the bloodstream, systemic transportation, extravasation into the liver, and colonization in the liver. The colon mimic uses established normal colon epithelial organoid cells (NL) and human umbilical vein endothelial cells (HUVEC) plated on opposite sides of a membrane. To better mimic the colon structure the NL side of the membrane is exposed to air to establish an air-liquid interface. The liver mimic consists of human liver sinusoidal endothelial cells (HHSEC) and epithelial hepatic cells (HepG2 C3A) plated in Matrigel on opposite sides of a membrane. Labeled colorectal cancer cells/clusters (CA) from organoids are introduced into an established normal colon epithelial cell (NL) layer from the same patient before assembly of the system or alternatively NL organoids and fluorescently labeled CA organoids from the same patient were prepared as a ratio of 10:1 NL:CA and established together before assembly of the system. Cell viability is greater than 85% in this system. We demonstrate that over 5 days of operation that the five steps of the metastatic cascade are replicated. This novel device allows an in vitro estimate of metastatic capability (as measured by using percentages of the labeled areas per device through ImageJ) in response to selected variables. In this study, the metastatic capability depends on the source of cancer cells (e.g., the patient), the clumping of cancer cells, glucose concentration, and oxygen levels (hypoxia). For the first time, this new in vitro system mimics all five steps of the metastatic cascade in a single device and provides a new device to probe and observe the process of metastasis in a human-based model in only 5 days. The rapid observation is due to the use of a high concentration of cancer cells in the colon (e.g. 10%) and the absence of the immune system. Our device makes it possible to probe aspects of each step of metastasis and interactions between steps.

Multi-cellular engineered living systems to assess reproductive toxicology

Toxicants and some drugs can negatively impact reproductive health. Many toxicants haven't been tested due to lack of available models. The impact of many drugs taken during pregnancy to address maternal health may adversely affect fetal development with life-long effects and clinical trials do not examine toxicity effects on the maternal-fetal interface, requiring indirect assessment of safety and efficacy. Due to current gaps in reproductive toxicological knowledge and limitations of animal models, multi-cellular engineered living systems may provide solutions for modeling reproductive physiology and pathology for chemical and xenobiotic toxicity studies. Multi-cellular engineered living systems, such as microphysiological systems (MPS) and organoids, model of functional units of tissues. In this review, we highlight the key functions and structures of human reproductive organs and well-known representative toxicants afflicting these systems. We then discuss current approaches and specific studies where scientists have used MPS or organoids to recreate in vivo markers and cellular responses of the female and male reproductive system, as well as pregnancy-associated placenta formation and embryo development. We provide specific examples of organoids and organ-on-chip that have been used for toxicological purposes with varied success. Finally, we address current issues related to usage of MPS, emerging techniques for improving upon these complications, and improvements needed to make MPS more capable in assessing reproductive toxicology. Overall, multi-cellular engineered living systems have considerable promise to serve as a suitable, alternative reproductive biological model compared to animal studies and 2D culture.

Rocking- and diffusion-based culture of tumor spheroids-on-a-chip

Tumor spheroids are now intensively investigated toward preclinical and clinical applications, necessitating the establishment of accessible and cost-effective methods for routine operations. Without losing the advantage of organ-chip technologies, we developed a rocking system for facile formation and culture of tumor spheroids in hydrogel microwells of a suspended membrane under microfluidic conditions. While the rocking is controlled with a step motor, the microfluidic device is made of two plastic plates, allowing plugging directly syringe tubes with Luer connectors. Upon injection of the culture medium into the tubes and subsequent rocking of the chip, the medium flows back and forth in the channel underneath the membrane, ensuring a diffusion-based culture. Our results showed that such a rocking- and diffusion-based culture method significantly improved the quality of the tumor spheroids when compared to the static culture, particularly in terms of growth rate, roundness, junction formation and compactness of the spheroids. Notably, dynamically cultured tumor spheroids showed increased drug resistance, suggesting alternative assay conditions. Overall, the present method is pumpless, connectionless, and user-friendly, thereby facilitating the advancement of tumor-spheroid-based applications.

Evaluation of gelatin-based hydrogels for colon and pancreas studies using 3D in vitro cell culture

Biomimetic 3D models emerged some decades ago to address 2D cell culture limitations in the field of replicating biological phenomena, structures or functions found in nature. The fabrication of hydrogels for cancer disease research enables the study of cell processes including growth, proliferation and migration and their 3D design is based on the encapsulation of tumoral cells within a tunable matrix. In this work, a platform of gelatin methacrylamide (GelMA)-based photocrosslinked scaffolds with embedded colorectal (HCT-116) or pancreatic (MIA PaCa-2) cancer cells is presented. Prior to cell culture, the mechanical characterization of hydrogels was assessed in terms of stiffness and swelling behavior. Modifications of the UV curing time enabled a fine tuning of the mechanical properties, which at the same time, showed susceptibility to the chemical composition and crosslinking mechanism. All scaffolds displayed excellent cytocompatibility with both tumoral cells while eliciting various cell responses depending on the microenvironment features. Individual and collective cell migration were observed for HCT-116 and MIA PaCa-2 cell lines, highlighting the ability of the colorectal cancer cells to cluster into aggregates of different sizes governed by the surrounding matrix. Additionally, metabolic activity results pointed out to the development of a more proliferative phenotype within stiffer networks. These findings confirm the suitability of the presented platform of GelMA-based hydrogels to conduct 3D cell culture experiments and explore biological processes associated with colorectal and pancreatic cancer.

Use and application of organ-on-a-chip platforms in cancer research

Tumors are a major cause of death worldwide, and much effort has been made to develop appropriate anti-tumor therapies. Existing in vitro and in vivo tumor models cannot reflect the critical features of cancer. The development of organ-on-a-chip models has enabled the integration of organoids, microfluidics, tissue engineering, biomaterials research, and microfabrication, offering conditions that mimic tumor physiology. Three-dimensional in vitro human tumor models that have been established as organ-on-a-chip models contain multiple cell types and a structure that is similar to the primary tumor. These models can be applied to various foci of oncology research. Moreover, the high-throughput features of microfluidic organ-on-a-chip models offer new opportunities for achieving large-scale drug screening and developing more personalized treatments. In this review of the literature, we explore the development of organ-on-a-chip technology and discuss its use as an innovative tool in basic and clinical applications and summarize its advancement of cancer research.

Pumped and pumpless microphysiological systems to study (nano)therapeutics

Fluidic microphysiological systems (MPS) are microfluidic cell culture devices that are designed to mimic the biochemical and biophysical in vivo microenvironments of human tissues better than conventional petri dishes or well-plates. MPS-grown tissue cultures can be used for probing new drugs for their potential primary and secondary toxicities as well as their efficacy. The systems can also be used for assessing the effects of environmental nanoparticles and nanotheranostics, including their rate of uptake, biodistribution, elimination, and toxicity. Pumpless MPS are a group of MPS that often utilize gravity to recirculate cell culture medium through their microfluidic networks, providing some advantages, but also presenting some challenges. They can be operated with near-physiological amounts of blood surrogate (i.e., cell culture medium) that can recirculate in bidirectional or unidirectional flow patterns depending on the device configuration. Here we discuss recent advances in the design and use of both pumped and pumpless MPS with a focus on where pumpless devices can contribute to realizing the potential future role of MPS in evaluating nanomaterials. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.

Microphysiological Drug-Testing Platform for Identifying Responses to Prodrug Treatment in Primary Leukemia

Despite increasing survival rates of pediatric leukemia patients over the past decades, the outcome of some leukemia subtypes has remained dismal. Drug sensitivity and resistance testing on patient-derived leukemia samples provide important information to tailor treatments for high-risk patients. However, currently used well-based drug screening platforms have limitations in predicting the effects of prodrugs, a class of therapeutics that require metabolic activation to become effective. To address this issue, a microphysiological drug-testing platform is developed that enables co-culturing of patient-derived leukemia cells, human bone marrow mesenchymal stromal cells, and human liver microtissues within the same microfluidic platform. This platform also enables to control the physical interaction between the diverse cell types. Herein, it is made possible to recapitulate hepatic prodrug activation of ifosfamide in their platform, which is very difficult in traditional well-based assays. By testing the susceptibility of primary patient-derived leukemia samples to the prodrug ifosfamide, sample-specific sensitivities to ifosfamide in primary leukemia samples are identified. The microfluidic platform is found to enable the recapitulation of physiologically relevant conditions and the testing of prodrugs including short-lived and unstable metabolites. The platform holds great potential for clinical translation and precision chemotherapy selection.

Organ-on-a-Chip Platforms for Drug Screening and Delivery in Tumor Cells: A Systematic Review

Simple Summary

Cancer is one of the diseases with a high mortality rate worldwide. Of the current strategies to study new diagnostic and treating tools, organs-on-chip are quite promising regarding the achievement of more personalized medicine. In this work, 75 out of 820 of the most recent published scientific articles were selected and analyzed through a systematic process. The selected articles present the different microfluidic platforms where cell culture was introduced and was used for the evaluation of cancer treatments efficacy and/or toxicity.

Abstract

The development of cancer models that rectify the simplicity of monolayer or static cell cultures physiologic microenvironment and, at the same time, replicate the human system more accurately than animal models has been a challenge in biomedical research. Organ-on-a-chip (OoC) devices are a solution that has been explored over the last decade. The combination of microfluidics and cell culture allows the design of a dynamic microenvironment suitable for the evaluation of treatments’ efficacy and effects, closer to the response observed in patients. This systematic review sums the studies from the last decade, where OoC with cancer cell cultures were used for drug screening assays. The studies were selected from three databases and analyzed following the research guidelines for systematic reviews proposed by PRISMA. In the selected studies, several types of cancer cells were evaluated, and the majority of treatments tested were standard chemotherapeutic drugs. Some studies reported higher drug resistance of the cultures on the OoC devices than on 2D cultures, which indicates the better resemblance to in vivo conditions of the former. Several studies also included the replication of the microvasculature or the combination of different cell cultures. The presence of vasculature can influence positively or negatively the drug efficacy since it contributes to a greater diffusion of the drug and also oxygen and nutrients. Co-cultures with liver cells contributed to the evaluation of the systemic toxicity of some drugs metabolites. Nevertheless, few studies used patient cells for the drug screening assays.

Organotypic and Microphysiological Human Tissue Models for Drug Discovery and Development-Current State-of-the-Art and Future Perspectives

The number of successful drug development projects has been stagnant for decades despite major breakthroughs in chemistry, molecular biology, and genetics. Unreliable target identification and poor translatability of preclinical models have been identified as major causes of failure. To improve predictions of clinical efficacy and safety, interest has shifted to three-dimensional culture methods in which human cells can retain many physiologically and functionally relevant phenotypes for extended periods of time. Here, we review the state of the art of available organotypic culture techniques and critically review emerging models of human tissues with key importance for pharmacokinetics, pharmacodynamics, and toxicity. In addition, developments in bioprinting and microfluidic multiorgan cultures to emulate systemic drug disposition are summarized. We close by highlighting important trends regarding the fabrication of organotypic culture platforms and the choice of platform material to limit drug absorption and polymer leaching while supporting the phenotypic maintenance of cultured cells and allowing for scalable device fabrication. We conclude that organotypic and microphysiological human tissue models constitute promising systems to promote drug discovery and development by facilitating drug target identification and improving the preclinical evaluation of drug toxicity and pharmacokinetics. There is, however, a critical need for further validation, benchmarking, and consolidation efforts ideally conducted in intersectoral multicenter settings to accelerate acceptance of these novel models as reliable tools for translational pharmacology and toxicology. SIGNIFICANCE STATEMENT: Organotypic and microphysiological culture of human cells has emerged as a promising tool for preclinical drug discovery and development that might be able to narrow the translation gap. This review discusses recent technological and methodological advancements and the use of these systems for hit discovery and the evaluation of toxicity, clearance, and absorption of lead compounds.