Methods for assessing the viability of cells cultured in vitro in 2D and 3D structures

Over the past decades, cell viability tests have been an essential research tool in cell biology, tissue engineering, and regenerative medicine. Assessment of cell viability is mandatory in the production and quality control of cell products for biomedical applications. Methods of viability assessment can be broadly classified according to the underlying mechanism and how the results obtained are evaluated. This article presents variants of the most commonly used tests and protocols for assessing cell viability. Their advantages and disadvantages are presented, which should be considered when planning experiments, e.g., when developing cell preparations for regenerative medicine. The authors point out the main factors influencing the choice of viability assessment method: efficiency, speed, safety, reproducibility, sample integrity, compatibility with biomaterial, and cell line type. Finally, the authors discuss separately cell viability tests that can be applied not only to 2D cell structures but also to 3D cell structures, which have recently become widespread due to more accurate modeling of biological processes.