Three‐dimensional cell culture models for anticancer drug screening: Worth the effort?

Abstract

High attrition of new oncology drug candidates in clinical trials is partially caused by the poor predictive capacity of artificial monolayer cell culture assays early in drug discovery. Monolayer assays do not take the natural three-dimensional (3D) microenvironment of cells into account. As a result, false positive compounds often enter clinical trials, leading to high dropout rates and a waste of time and money. Over the past 2 decades, tissue engineers and cell biologists have developed a broad range of 3D in vitro culturing tools that better represent in vivo cell biology. These tools preserve the 3D architecture of cells and can be used to predict toxicity of and resistance against antitumor agents. Recent progress in tissue engineering further improves 3D models by taking into account the tumor microenvironment, which is important for metastatic progression and vascularization. However, the widespread implementation of 3D cell cultures into cell-based research programs has been limited by various factors, including their cost and reproducibility. In addition, different 3D cell culture techniques often produce spheroids of different size and shape, which can strongly influence drug efficacy and toxicity. Hence, it is imperative to morphometrically characterize multicellular spheroids to avoid generalizations among different spheroid types. Standardized 3D culturing procedures could further reduce data variability and enhance biological relevance. Here, we critically evaluate the benefits and challenges inherent to growing cells in 3D, along with an overview of the techniques used to form spheroids. This is done with a specific focus on antitumor drug screening.

Three‐Dimensional (3D) cell culture monitoring: Opportunities and challenges for impedance spectroscopy

“…Therefore, there is a need to characterize and standardize monitoring techniques across different laboratories. This will increase the scope of 3D culture as well as ease its implementation (Verjans et al, 2017). Further, it will allow researchers to select matured tissues that are physiologically relevant in their contexts and allow them to perform experiments in a more controlled environment where variability within cultures can be monitored.…”

“…The physiological differences induced by the different attachment modes and the resulting cell/media interactions mean that cellular functions such as proliferation, differentiation, survival, and mechanical signaling vary between 2D and 3D cell cultures. The details of these variations have been reviewed extensively (Duval et al, 2017), and many studies have shown variations in metabolism between 2D and 3D systems (Brajša, Trzun, Zlatar, & Jelić, 2016; Verjans, Doijen, Luyten, Landuyt, & Schoofs, 2017) leading to a focus of these systems for early‐stage drug testing and disease progression.…”

Progress in melanoma modelling in vitro

“…The scaffold‐based method consists in the use of a porous 3D scaffold which physically supports cell aggregation, allowing the formation of MCTS with a controlled size. Several scaffolds have been developed, in particular, Gong et al created an agarose‐based scaffold consisting in a micropore scaffold adaptable to 6‐ to 24‐well plates. This system allows the rapid cellular assembly of cells to MCTS, and it is completely transparent, allowing to monitor the spheroids formation by optical microscope …”

Modeling the Efficacy of Oncolytic Adenoviruses In Vitro and In Vivo: Current and Future Perspectives

“…Testing OAd spread and replication in tumor spheroid models more closely mimics the in vivo setting compared to 2D monolayer cultures where the majority of cells are exposed to virus initially after infection [44]. One study showed that only about 23% of cells in a spheroid are exposed to the surface and thus an oxygen rich environment, while cells on the interior of the sphere have limited nutrients and low pH, as inside a solid tumor [40].…”

“…Collagen, fibronectin, elastin, and laminin make up the highly heterogenous and dynamic non-cellular structure of the tumor ECM, which is not only tissue specific, but also can be continually remodeled in vivo [50]. Hydrogels can be made of natural or synthetic ECM polymers such as Matrigel, collagen, or polyethylene glycol (PEG), but all provide a scaffold that maintains the biological phenotype of the cells and promotes nutrient exchange for long-term culture [44]. Hydrogels can also easily co-culture fibroblasts and endothelial cells with tumor cells [31].…”