Biomedical Engineering Reference
In-Depth Information
t = 21.8 h
t = 46.3 h
t = 71.7 h
(A)
(C)
(E)
(B)
(D)
(F)
Figure 6.10
DHM analysis of vacuolated HBMECs. (A), (C), (E) White light images of HBMECs at different
time points after exposure to VD90 of EHEC-Vac; (B), (D), (F) corresponding quantitative DHM
phase contrast images. Cells designated “A” and “B” are examples of heavily vacuolated cells that
underwent necrosis after different times of exposure to EHEC-Vac. Arrows in panels (E) and (F)
indicate cellular leakage and the release of the cytoplasmic content from necrotic cells. The scale
bars correspond to 10
μ
m. Source: Modified from Ref. [77] .
apoptotic and necrotic processes. In the first experiment, PaTu 8988 T cells were exposed
to cell death inducing concentrations of taxol. Digital holograms of the cells were recorded
continuously every 2 min in a temperature-stabilized environment (37 C) for 12 h.
Figure 6.11 shows exemplarily time-dependent results for the obtained unwrapped digital
holographic phase distributions of two cells (denoted as A and B) after taxol addition in
comparison to phase contrast images from a control measurement of two cells (denoted as
C and D) without the addition of taxol. The phase contrast images in the upper row of
Figure 6.11 show fast morphologic changes. The appearance of several small spherical cell
fragments indicates apoptotic cell death. A second measurement without toxin addition was
done. Here rather a necrotic process due to changes in pH value of the cell culture medium
was observed at the end of the experiment in which the cells leak and release the cytoplasm
to the cell culture medium as shown in the lower row of Figure 6.11 . Although the images
in Figure 6.11 clearly indicate apoptotic and necrotic effects, further investigations with
apoptosis assays are necessary to validate the quantitative phase data. Nevertheless, it is
illustrated that DHM has potentials to be a helpful label-free tool to study drug effects on
cells' morphology quantitatively.
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