3D Cell Cultring by Magnetic Levitation, the Next Generation of Cell Culturing?

Glauco R. Souza
Chief Scientific Officer
n3D Biosciences, Inc.
Presented in the Embryo Physics Course, February 8, 2012


In vitro cell culturing is an essential process in emerging areas of biotechnology, such as stem cell research, regenerative medicine, tissue engineering, and drug discovery. Traditional cell culturing is carried out in Petri dishes or media-filled flasks where cells usually attach onto a flat glass or plastic surface in a two-dimensional (2D) cell monolayer. Cells grown in monolayers provide a poor representation of in vivo conditions and are widely acknowledged to be insufficient for demanding technological needs. Many schemes for three-dimensional (3D) culturing are being developed or marketed to address these challenges, such as bio-reactors or protein-based gel environments, but they typically suffer from high cost, low-throughput, poor scalability, complexity, or the presence of non-human biological factors that can alter cell behavior and preclude therapeutic use. The next generation of cell culturing tools should address these challenges in an integrated manner. In this presentation, I will give a general overview of today’s 3D cell culturing tools, and present what is thought to be the next generation of 3D cell culturing, 3D cell culturing by magnetic levitation. Cell culturing by magnetic levitation consists of a device (The Bio-AssemblerTM) based on magnetization of cells using nanoparticle assemblies (Nanoshuttle) and levitation of the cells by spatially varying magnetic fields. In addition to addressing many of the unmet practical challenges in 3D cell culturing, magnetic levitation fosters tissue formation with phenotypic morphogenesis and functionality. The presence of the magnetic field levitates and spatially guides cells together, therefore promoting rapid cell-cell interaction in a manner that allows cells self-assemble, expand, and migrate in 3D. Importantly, this process of 3D cellular self-assembly takes place without the influence of an artificial ECM, and our results have shown that cells start to generate their endogenous ECM (human primary pulmonary fibroblast and smooth muscle cells) and assemble cells into physiologically relevant 3D cellular structures within hours of levitation. Furthermore, the efficiency and spatial control when generating 3D cultures enables the application of this method towards in vitro and label-free cell based assays. In this lecture we will present a wound-healing assay, where 3D cultures are generated by culturing/levitating embryonic kidney cells (HEK293). Our work shows the rate of wound closure can be used to quantitatively evaluate a dose-dependent response to ibuprofen (nephrotoxic agent), including determining the point of zero growth, which is in agreement with reported IC50 value with cultured HEK293 cells. We believe this simple assay has broad application in toxicity testing, cell-based drug discovery, and tissue engineering and reconstruction.



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