Magnetic-Based 3D Cell Culture
Pre-clinical cell-based assays have become a crucial tool in the advancement of biomedical and pharmaceutical studies, particularly in developing diagnostic tools, drug discovery, pathophysiological research, and regenerative medicine. Cell based assays allow for reduced use of expensive animal models and avoid ethically related issues. Nowadays, most cell-based assays still employ 2D cell culture models due to their inherent ease, low cost, and high reproducibility (1-4).
However, despite the recent technological advancement in cell culture, 90% of the therapeutic drugs developed still fail at clinical trials largely due to the inadequacy of 2D cell culture models to accurately represent the complex natural human microenvironment and predict cellular response to molecules (5).
Advantage of 3D cell cultures
To this extent, 3D cell cultures offer many advantages to overcome the limitations of 2D cell cultures. 3D cell cultures are able to recreate the microenvironment and cellular architecture that is observed in vivo, with cell-cell and cell-extracellular matrix (ECM) interactions mimicking intercellular communications. Additionally, oxygen and nutrient gradients in 3D cell culture models are similar to those of human tissues. Collectively, these advantages make 3D cell cultures a more attractive platform for translational research. Several 3D cell culture methods exist including hanging drop technique, scaffold-based cultures, use of hydrogels, cell sheets, microfluidic systems, rotary and bioreactors, and the most recent magnetic-based 3D (m3D) cell cultures (4,5).
M3D cell cultures
Magnetic-based 3D (m3D) cell cultures involve cell incubation in a 2D system with nanoparticles (MNP) named NanoShuttle™-PL which consists of a combination of iron oxide, gold and poly-L-lysine coated nanoparticles. MNP binds electrostatically and non-specifically to the cell membrane resulting in cell magnetization. Magnetized cells are then seeded in a 3D culture platform. Exposure of cells to magnetic fields generated by neodymium magnets causes aggregation of cells into 3D structures (1).
There are 3 types of magnetic based 3D models to date, all beginning with magnetization of cells followed by levitation, bio printing or ring formation to create different 3D structures.
Levitation method – Magnets are placed over the plate with seeded cells to promote levitation of magnetized cells in a liquid-air interface. Cell aggregation is then triggered by cell-cell and cell-ECM interactions (1,6).
The bioprinting method– Magnets are placed under the plate with seeded cells. 3D structures are then printed at the bottom of each well promoting cellular aggregation and matrix formation (1).
The ring formation method- 3D aggregated are first formed by levitating the magnetized cells, and then placing these plates over a magnetic unit consisting of ring-shaped neodymium magnet to induce cell aggregation into a toroidal shape (1).
Advantages of m3D technology
The magnetic-based technology is fairly simple to implement, it can be standardized across a wide range of cell types, and promotes fast, consistent formation of spheroid aggregates, and regulated cell movement and aggregation. There is also no requirement for an artificial matrix, as spheroids are able to form their own endogenous ECM during the aggregation process (1,6).
The advantages of m3D based cell cultures are now gaining more ground over a variety of research purposes. These include tumor models, physiological studies of 3D cellular architecture, and the optimization of other heterotypic 3D cultures, all leading to an overall advancement in human health research (7).
References
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Jensen, C.; Teng, Y. Is It Time to Start Transitioning From 2D to 3D Cell Culture? Front. Mol. Biosci. 2020, 7, 1–15.
Nunes, A.S.; Barros, A.S.; Costa, E.C.; Moreira, A.F.; Correia, I.J. 3D Tumor Spheroids as in Vitro Models to Mimic in Vivo Human Solid Tumors Resistance to Therapeutic Drugs. Biotechnol. Bioeng. 2019, 116, 206–226
Brancato, V.; Oliveira, J.M.; Correlo, V.M.; Reis, R.L.; Kundu, S.C. Could 3D Models of Cancer Enhance Drug Screening? Biomaterials 2020, 232, 119744. [
Marques IA, Fernandes C, Tavares NT, Pires AS, Abrantes AM, Botelho MF. Magnetic-Based Human Tissue 3D Cell Culture: A Systematic Review. International Journal of Molecular Sciences. 2022; 23(20):12681.
Haisler, W.L.; Timm, D.M.; Gage, J.A.; Tseng, H.; Killian, T.C.; Souza, G.R. Three-Dimensional Cell Culturing by Magnetic Levitation. Nat. Protoc. 2013, 8, 1940–1949.
Natânia de Souza-Araújo, C.; Rodrigues Tonetti, C.; Cardoso, M.R.; Lucci de Angelo Andrade, L.A.; Fernandes da Silva, R.; Romani Fernandes, L.G.; Guimarães, F. Three-Dimensional Cell Culture Based on Magnetic Fields to Assemble Low-Grade Ovarian Carcinoma Cell Aggregates Containing Lymphocytes. Cells 2020, 9, 635.
Türker, Esra & Arslan Yildiz, Ahu. (2018). Recent Advances in Magnetic Levitation: A Biological Approach from Diagnostics to Tissue Engineering. ACS Biomaterials Science & Engineering. 4. 10
