A novel 3D polycaprolactone high-throughput system for evaluation of toxicity in normoxia and hypoxia

High-throughput non-homogenous 3D polycaprolactone scaffold for cancer cell and cancer-associated fibroblast mini-tumors to evaluate drug treatment response

High-throughput screening (HTS) three-dimensional (3D) tumor models are a promising approach for cancer drug discovery, as they more accurately replicate in vivo cell behavior than two-dimensional (2D) models. However, assessing and comparing current 3D models for drug efficacy remains essential, given the significant influence of cellular conditions on treatment response. To develop in vivo mimicking 3D models, we evaluated two HTS 3D models established in 96-well plates with 3D polycaprolactone (PCL) scaffolds fabricated using two distinct methods, resulting in scaffolds with either homogenous or non-homogenous fiber networks. These models, based on human HeLa cervical cancer cells and cancer-associated fibroblasts (CAFs) cultured as mono- or co-cultures within the 3D scaffolds, revealed that anticancer drug paclitaxel (PTX) exhibited consistently higher inhibitory concentration 50 (IC50) in 3D (≥ 1000 nM) compared to 2D (≥ 100 nM), indicating reduced toxicity on cells cultured in 3D. Interestingly, the toxicity of PTX was significantly lower on mini-tumors in non-homogenous 3D (IC50: 600 or 1000 nM) than in homogenous 3D cultures (IC50 exceeding 1000 nM). Microscopic studies revealed that the non-homogenous scaffolds closely resemble the tumor collagen network than their homogeneous counterpart. Both 3D scaffolds offer optimal pore size, facilitating efficient cell infiltration into the depth of 58.1 ± 1.2 µm (homogenous) and 86.4 ± 9.8 µm (non-homogenous) within 3D cultures. Cells cultured in the 3D non-homogenous systems exhibited drug treatment responses closer to in vivo conditions, highlighting the role of scaffold structure and design on cellular response to drug treatment. The PCL-based 3D models provide a robust, tunable, and efficient approach for the HTS of anti-cancer drugs compared to conventional 2D systems.

Advancing humanized 3D tumor modeling using an open access xeno-free medium

Despite limitations like poor mimicry of the human cell microenvironment, contamination risks, and batch-to-batch variation, cell culture media with animal-derived components such as fetal bovine serum (FBS) have been used in vitro for decades. Moreover, a few reports have used animal-product-free media in advanced high throughput three-dimensional (3D) models that closely mimic in vivo conditions. To address these challenges, we combined a high throughput 3D model with an open access, FBS-free chemically-defined medium, Oredsson Universal Replacement (OUR) medium, to create a more realistic 3D in vitro drug screening system. To reach this goal, we report the gradual adaptation procedure of three cell lines: human HeLa cervical cancer cells, human MCF-7 breast cancer cells, and cancer-associated fibroblasts (CAFs) from FBS-supplemented medium to OUR medium, while closely monitoring cell attachment, proliferation, and morphology. Our data based on cell morphology studies with phase contrast and real-time live imaging demonstrates a successful adaptation of cells to proliferate in OUR medium showing sustained growth kinetics and maintaining population doubling time. The morphological analysis demonstrates that HeLa and MCF-7 cells displayed altered cell morphology, with a more spread-out cytoplasm and significantly lower circularity index, while CAFs remained unaffected when grown in OUR medium. 3D fiber scaffolds facilitated efficient cell distribution and ingrowth when grown in OUR medium, where cells expand and infiltrate into the depths of 3D scaffolds. Drug toxicity evaluation of the widely used anti-cancer drug paclitaxel (PTX) revealed that cells grown in 3D cultures with OUR medium showed significantly lower sensitivity to PTX, which was consistent with the FBS-supplemented medium. We believe this study opens the way and encourages the scientific community to use animal product-free cell culture medium formulations for research and toxicity testing.

Advances in high throughput cell culture technologies for therapeutic screening and biological discovery applications

Cellular phenotypes and functional responses are modulated by the signals present in their microenvironment, including extracellular matrix (ECM) proteins, tissue mechanical properties, soluble signals and nutrients, and cell-cell interactions. To better recapitulate and analyze these complex signals within the framework of more physiologically relevant culture models, high throughput culture platforms can be transformative. High throughput methodologies enable scientists to extract increasingly robust and broad datasets from individual experiments, screen large numbers of conditions for potential hits, better qualify and predict responses for preclinical applications, and reduce reliance on animal studies. High throughput cell culture systems require uniformity, assay miniaturization, specific target identification, and process simplification. In this review, we detail the various techniques that researchers have used to face these challenges and explore cellular responses in a high throughput manner. We highlight several common approaches including two-dimensional multiwell microplates, microarrays, and microfluidic cell culture systems as well as unencapsulated and encapsulated three-dimensional high throughput cell culture systems, featuring multiwell microplates, micromolds, microwells, microarrays, granular hydrogels, and cell-encapsulated microgels. We also discuss current applications of these high throughput technologies, namely stem cell sourcing, drug discovery and predictive toxicology, and personalized medicine, along with emerging opportunities and future impact areas.

3D cell subculturing pillar dish for pharmacogenetic analysis and high-throughput screening

A pillar dishe for subculture of 3D cultured cells on hydrogel spots (Matrigel and alginate) have been developed. Cells cultured in 3D in an extracellular matrix (ECM) can retain their intrinsic properties, but cells cultured in 2D lose their intrinsic properties as the cells stick to the bottom of the well. Previously, cells and ECM spots were dispensed on a conventional culture dish for 3D cultivation. However, as the spot shape and location depended on user handling, pillars were added to the dish to realize uniform spot shape and stable subculture, supporting 3D cell culture-based high-throughput screening (HTS). Matrigel and alginate were used as ECMs during 6-passage subculture. The growth rate of lung cancer cell (A549) was higher on Matrigel than on alginate. Cancer cell was subcultured in three dimensions in the proposed pillar dish and used for drug screening and differential gene expression analysis. Interestingly, stemness markers, which are unique characteristics of lung cancer cells inducing drug resistance, were upregulated in 3D-subcultured cells compared with those in 2D-subcultured cells. Additionally, the PI3K/Akt/mTOR, VEGFR1/2, and Wnt pathways, which are promising therapeutic targets for lung cancer, were activated, showing high drug sensitivity under 3D-HTS using the 3D-subcultured cells.

A new animal product free defined medium for 2D and 3D culturing of normal and cancer cells to study cell proliferation and migration as well as dose response to chemical treatment

Cell culturing methods are increasingly used to reduce and replace the use of live animals in biomedical research and chemical toxicity testing. Although live animals are avoided when using cell culturing methods, they often contain animal-derived components of which one of the most commonly used is foetal bovine serum (FBS). FBS is added to cell culture media among other supplements to support cell attachment/spreading and cell proliferation. The safety, batch-to-batch variation, and ethical problems with FBS are acknowledged and therefore world-wide efforts are ongoing to produce FBS free media. Here, we present the composition of a new defined medium with only human proteins either recombinant or derived from human tissues. This defined medium supports long-term culturing/routine culturing of normal cells and of cancer cells, and can be used for freezing and thawing of cells, i.e. for cell banking. Here, we show for our defined medium, growth curves and dose response curves of cells grown in two and three dimensions, and applications such as cell migration. Cell morphology was studied in real time by phase contrast and phase holographic microscopy time-lapse imaging. The cell lines used are human cancer-associated fibroblasts, keratinocytes, breast cancer JIMT-1 and MDA-MB-231 cells, colon cancer CaCo-2 cells, and pancreatic cancer MiaPaCa-2 cells as well as the mouse L929 cell line. In conclusion, we present the composition of a defined medium without animal-derived products which can be used for routine culturing and in experimental settings for normal cells and for cancer cells, i.e. our defined medium provides a leap towards a universal animal product free cell culture medium.