Microfluidic Droplet-Assisted Fabrication of Vessel-Supported Tumors for Preclinical Drug Discovery

High-fidelity in vitro tumor models are important for preclinical drug discovery processes. Currently, the most commonly used model for in vitro drug testing remains the two-dimensional (2D) cell monolayer. However, the natural in vivo tumor microenvironment (TME) consists of extracellular matrix (ECM), supporting stromal cells and vasculature. They not only participate in the progression of tumors but also hinder drug delivery and effectiveness on tumor cells. Here, we report an integrated engineering system to generate vessel-supported tumors for preclinical drug screening. First, gelatin-methacryloyl (GelMA) hydrogel was selected to mimic tumor extracellular matrix (ECM). HCT-116 tumor cells were encapsulated into individual micro-GelMA beads with microfluidic droplet technique to mimic tumor-ECM interactions in vitro. Then, normal human lung fibroblasts were mingled with tumor cells to imitate the tumor-stromal interaction. The tumor cells and fibroblasts reconstituted in the individual GelMA microbead and formed a biomimetic heterotypic tumor model with a core-shell structure. Next, the cell-laden beads were consociated into a functional on-chip vessel network platform to restore the tumor-tumor microenvironment (TME) interaction. Afterward, the anticancer drug paclitaxel was tested on the individual and vessel-supported tumor models. It was demonstrated that the blood vessel-associated TME conferred significant additional drug resistance in the drug screening experiment. The reported system is expected to enable the large-scale fabrication of vessel-supported heterotypic tumor models of various cellular compositions. It is believed to be promising for the large-scale fabrication of biomimetic in vitro tumor models and may be valuable for improving the efficiency of preclinical drug discovery processes.

3D-bioprinted cancer-on-a-chip: level-up organotypic in vitro models

Combinatorial conjugation of organ-on-a-chip platforms with additive manufacturing technologies is rapidly emerging as a disruptive approach for upgrading cancer-on-a-chip systems towards anatomic-sized dynamic in vitro models. This valuable technological synergy has potential for giving rise to truly physiomimetic 3D models that better emulate tumor microenvironment elements, bioarchitecture, and response to multidimensional flow dynamics. Herein, we showcase the most recent advances in bioengineering 3D-bioprinted cancer-on-a-chip platforms and provide a comprehensive discussion on design guidelines and possibilities for high-throughput analysis. Such hybrid platforms represent a new generation of highly sophisticated 3D tumor models with improved biomimicry and predictability of therapeutics performance.

Perfusion-Based Bioreactor Culture and Isothermal Microcalorimetry for Preclinical Drug Testing with the Carbonic Anhydrase Inhibitor SLC-0111 in Patient-Derived Neuroblastoma

Neuroblastoma is a rare disease. Rare are also the possibilities to test new therapeutic options for neuroblastoma in clinical trials. Despite the constant need to improve therapy and outcomes for patients with advanced neuroblastoma, clinical trials currently only allow for testing few substances in even fewer patients. This increases the need to improve and advance preclinical models for neuroblastoma to preselect favorable candidates for novel therapeutics. Here we propose the use of a new patient-derived 3D slice-culture perfusion-based 3D model in combination with rapid treatment evaluation using isothermal microcalorimetry exemplified with treatment with the novel carbonic anhydrase IX and XII (CAIX/CAXII) inhibitor SLC-0111. Patient samples showed a CAIX expression of 18% and a CAXII expression of 30%. Corresponding with their respective CAIX expression patterns, the viability of SH-EP cells was significantly reduced upon treatment with SLC-0111, while LAN1 cells were not affected. The inhibitory effect on SH-SY5Y cells was dependent on the induction of CAIX expression under hypoxia. These findings corresponded to thermogenesis of the cells. Patient-derived organotypic slice cultures were treated with SLC-0111, which was highly effective despite heterogeneity of CAIX/CAXII expression. Thermogenesis, in congruence with the findings of the histological observations, was significantly reduced in SLC-0111-treated samples. In order to extend the evaluation time, we established a perfusion-based approach for neuroblastoma tissue in a 3D perfusion-based bioreactor system. Using this system, excellent tissue quality with intact tumor cells and stromal structure in neuroblastoma tumors can be maintained for 7 days. The system was successfully used for consecutive drug response monitoring with isothermal microcalorimetry. The described approach for drug testing, relying on an advanced 3D culture system combined with a rapid and highly sensitive metabolic assessment, can facilitate development of personalized treatment strategies for neuroblastoma.

In vitro models replicating the human intestinal epithelium for absorption and metabolism studies: A systematic review

Absorption, distribution, metabolism and excretion (ADME) studies represent a fundamental step in the early stages of drug discovery. In particular, the absorption of orally administered drugs, which occurs at the intestinal level, has gained attention since poor oral bioavailability often led to failures for new drug approval. In this context, several in vitro preclinical models have been recently developed and optimized to better resemble human physiology in the lab and serve as an animal alternative to accomplish the 3Rs principles. However, numerous models are ineffective in recapitulating the key features of the human small intestine epithelium and lack of prediction potential for drug absorption and metabolism during the preclinical stage. In this review, we provide an overview of in vitro models aimed at mimicking the intestinal barrier for pharmaceutical screening. After briefly describing how the human small intestine works, we present i) conventional 2D synthetic and cell-based systems, ii) 3D models replicating the main features of the intestinal architecture, iii) micro-physiological systems (MPSs) reproducing the dynamic stimuli to which cells are exposed in the native microenvironment. In this review, we will highlight the benefits and drawbacks of the leading intestinal models used for drug absorption and metabolism studies.

A near-infrared fluorescent voltage-sensitive dye allows for moderate-throughput electrophysiological analyses of human induced pluripotent stem cell-derived cardiomyocytes

Human induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM)-based assays are emerging as a promising tool for the in vitro preclinical screening of QT interval-prolonging side effects of drugs in development. A major impediment to the widespread use of human iPSC-CM assays is the low throughput of the currently available electrophysiological tools. To test the precision and applicability of the near-infrared fluorescent voltage-sensitive dye 1-(4-sulfanatobutyl)-4-{β[2-(di-n-butylamino)-6-naphthyl]butadienyl}quinolinium betaine (di-4-ANBDQBS) for moderate-throughput electrophysiological analyses, we compared simultaneous transmembrane voltage and optical action potential (AP) recordings in human iPSC-CM loaded with di-4-ANBDQBS. Optical AP recordings tracked transmembrane voltage with high precision, generating nearly identical values for AP duration (AP durations at 10%, 50%, and 90% repolarization). Human iPSC-CMs tolerated repeated laser exposure, with stable optical AP parameters recorded over a 30-min study period. Optical AP recordings appropriately tracked changes in repolarization induced by pharmacological manipulation. Finally, di-4-ANBDQBS allowed for moderate-throughput analyses, increasing throughput >10-fold over the traditional patch-clamp technique. We conclude that the voltage-sensitive dye di-4-ANBDQBS allows for high-precision optical AP measurements that markedly increase the throughput for electrophysiological characterization of human iPSC-CMs.