Background:
Even years after successful treatment of the primary tumor about one third of breast
cancer patients are suffering from metastatic relapse. One reason might be hematogenous
spread during early disease stages when isolated tumor cells change their physical
properties from epithelial to mesenchymal features (EMT) and become able to disseminate
from the primary tumor site. Therefore circulating tumor cells (CTCs) might be interesting
and easy accessible surrogate markers to monitor disease progression and treatment
response in the clinical setting.
Methodology and Results:
One promising CTC detection approach could be based on mechanical properties such
as deformability using an optical rheometer. PBMC were isolated from the peripheral
blood of a healthy donor using density gradient centrifugation. Breast cancer cells
MDA-MB 231 were cultured under standard conditions. Both cell suspensions were applied
separately to the optical stretcher and rheological parameters such as deformability
and stiffness were measured. Distinct cellular profiles could be obtained from hematopoetic
cells and breast cancer cells, respectively. Relative deformation was significantly
different between both cell types. Furthermore, 10:1 mixtures of PBMC and MDA-MB 231
cells were analyzed with the optical stretcher. Results indicated that the mixed samples
could be sorted into subpopulations of significantly different cellular stiffness
based on mechanical parameters such as cell size.
Conclusions and Outlook:
Once significant differences between cellular profiles of the mixed samples with low
numbers of spiked tumor cells can be measured, the methodology might be transferred
to clinical samples in order to develop a liquid biopsy test.
