BioTek July 2019 - 9

imaging. BioTek's Cytation™ 5 Cell Imaging MultiMode Reader, equipped with high contrast brightfield, enables users to quantify cells by counting
them individually or by making confluence measurements (via BioTek's Gen™ 5 image analysis
software), to assess the antiproliferative effects of
potential cancer drugs, for example. Label-free imaging can be especially useful when additional labels or stains may interfere with cell health or with
the measurements of proliferation profiles.
Cytation's high contrast brightfield optics cause
each individual cell in the field of view to refract
light in a distinct and bright spot, which can then
be counted by the software without the need for
separate cell labeling or nuclear staining. "Even
though fluorescence imaging will always have important uses, especially for experimental systems
like co-cultures, we see that label-free cell proliferation imaging is growing in the marketplace now,"
says Banks. It is especially suited for testing the effects of anti-proliferative agents on cell proliferation profiles as recently shown by BioTek using the
Cytation 5 system.

Figure 1. Change in HCT116 cell count and pH over time in confluent
cultures. HCT116 cells were seeded at a density of 2000 cells per well. After
24 hours to allow for attachment, image-based and absorbance analysis
were performed on 96-well plate cultures every 2 hours for 5 days. The pH
was determined by interpolating the 415/560 ratio values with a previously
generated calibration curve. Data represents the mean and SEM for 96
determinations at each data point.

This unique combination means that researchers
who are studying antiproliferative agents can have
greater confidence in their results. Measurements
of cell numbers are commonly used to test the effects of antiproliferation drugs. For example, if they
observe that cell cultures treated with an antiproliferation compound are lower in cell number, it may
be unclear whether the effect is directly attributable to a drug, because deterioration in cell culture
conditions could also explain the result. Monitoring
the change in media pH through absorbance measurements with the Cytation 5 can also indicate to
researchers that a media exchange is warranted in
a long-term kinetic experiment.

Label-free imaging of
cell proliferation
Another important new tool for long-term kinetic
cell proliferation studies (continuous live cell assays
that measure cell proliferation profiles) is label-free

Figure 2. Label-free direct cell count profiles for NIH3T3, HeLa, and HCT116.
Cells were imaged every 2 hours and culture growth was monitored for 5 days
or until cell counts plateaued.

https://www.biotek.com/assets/tech_resources/Kinetic%20Proliferation%20Assay%20using%20Label-Free%20Cell%20Counting_App_Note.pdf

BioTek July 2019

Table of Contents for the Digital Edition of BioTek July 2019