Applications - Presentations
Generation of Automated Label-Free Cell Migration Assays through the Incorporation of Magnetic 3D Bioprinting
Authors: Brad Larson, BioTek Instruments, Inc; Glauco R. Souza, Nano3D Biosciences, Inc.
Cell migration involves a cyclical coordinated procedure starting with cell polarization, protrusion and substrate attachment of the leading edge, in addition to proteolytic degradation of physical barriers (e.g. tissue components and actinomyosin contraction) before the cell moves. Migration plays a central role in multiple beneficial physiological processes such as wound healing, in addition to being the first step in tumor metastasis as cells move away from the primary tumor site. Therefore, an advanced knowledge and methodology for monitoring phenotypic cell migration is useful for screening potential negative cytotoxic effects in test molecules, as well as speeding the development of novel therapies to re-establish wound healing abilities in pathologic tissue or control metastatic cellular invasion. Multiple techniques currently exist to assess cell migration. These commonly involve monitoring the migration of cells adhered to labware. The easiest and most sensitive of these methods incorporate label-free imaging to precisely track cell movement without introducing fluorescent probes that have the capability of changing normal cell activity. However, there are limitations to these migration assays. First, these assays use monolayers, which poorly mimic native tissue environments. In particular, these monolayers do not simulate tissue structure and properties, have altered cell exposure to compounds, and lack normal cell-cell and cell-extracellular matrix (ECM) interactions that characterize living tissue. Thus, cell migration witnessed in monolayers may misrepresent behavior seen in vivo.
Three-dimensional (3D) cell culture platforms are potential solutions as they can reconstruct tissue structure and environments in vitro. In particular, incorporation of magnetic 3D bioprinting, where cells are magnetized and printed into appropriate 3D cell cultures, provides a method to reestablish missing interactions and easily create 3D phenotypic cell migration assays. Using this method, cells are magnetized with a biocompatible nanoparticle assembly consisting of gold, iron oxide, and poly-L-lysine that electrostatically and non-specifically attaches to cell membranes. Magnetized cells can then be directed using mild magnetic forces to form aggregates where cells interact and build larger 3D environments with ECM that represent native tissues. Cells and matrix can then be printed into different configurations to assess wound healing and metastatic cell movement. Here we present two bioprinting procedures that were created to allow 3D wound healing and metastatic cell movement to take place in vitro. Label-free cell migration was tracked over time using automated widefield microscopy. Final combined processes were tested using multiple skin and cancer cell models in 384-well format to demonstrate that the incorporation of 3D magnetic bioprinting can lead to the generation of in vivo-like cell migration data.
Cytation 5 Cell Imaging Multi-Mode Reader