Tuesday, August 14, 2018

AMX™ Automated Media Exchange Module: A New Tool to Simplify Gentle Media Exchanges for Unattached Spheroid Cell Models

It has been widely proven that culturing cells in a three-dimensional (3D) format gives rise to increased cell-cell and cell-matrix interactions and also promotes more biosimilar cell morphologies and behaviors compared to cells cultured on flat 2D surfaces. As such, 3D cell models are being used with increasing frequency for long-term experiments to better mimic in vivo chronic dosing of a test molecule, and in higher density microplate formats to increase throughput. Media exchange and re-dosing steps are critically important during these tests to remove spent media and add fresh media or media with a test molecule. Due to simplicity of cell aggregation and replicate reproducibility, one of the most popular 3D cell culture methods incorporated into long-term test procedures involves the creation of unattached spheroids in media at the bottom of a round-bottom microplate coated to prevent cell attachment. However, with models such as these, care must be taken not to evacuate or damage the spheroid within each well during the exchange process. This can create aspirate and dispense steps that are time consuming and stressful, and can still yield lost spheroids, leading to the loss of critical data.

To alleviate this problem, BioTek has developed a novel peristaltic pump-based automated media exchange method. The AMX™ Automated Media Exchange module for the MultiFlo™ FX uses both available peristaltic pumps, one to dispense and one to aspirate media from the plate wells (Figure 1). The instrument is then programmed to perform the exchange process in a controlled manner that is optimized for the cell type and spheroid size used in each experiment.

MultiFlo FX AMX
Figure 1. MultiFlo FX Multi-Mode Dispenser equipped with the AMX Automated Media Exchange module,
showing aspirate (right arrow) and dispense (left arrow) heads.

During the aspiration step, tubes are positioned to the right of the well center and slightly elevated from the bottom. This allows for only a small residual volume to remain in the well, while ensuring that the spheroid itself is undisturbed (Figure 2).

To replace the removed media in 96-well plates, tubes are again positioned to the right of the well center and slightly elevated from the bottom (Figure 3). For 384-well format, tubes are positioned directly over the spheroid due to the smaller diameter of the well.

These combined aspiration and dispense steps create a method to gently replace spent media either in a single aspirate/dispense procedure for spheroid proliferation assays, or in a multi-step procedure for spheroid washing following fluorescent probe addition or as part of an immunofluorescence staining process.

We invite you to learn more about the AMX module, in addition to the qualitative and quantitative experiments performed to validate its use with multiple cell models and plate types by attending the upcoming webinar:

September 19, 2018
For more information and to register, click here.

By: BioTek Instruments, Brad Larson, Principal Scientist

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