Cancer metastasis is a multistep process during which tumor cells leave
the primary tumor mass and form distant secondary colonies that are
lethal. Circulating tumor cells (CTCs) are transported by body fluids to
reach distant organs, where they will extravasate and either remain
dormant or form new tumor foci. Development of methods to study the
behavior of CTCs at the late stages of the intravascular journey is thus
required to dissect the molecular mechanisms at play. Using recently
developed microfluidics approaches, we have demonstrated that CTCs
arrest intravascularly, through a two-step process: (a) CTCs stop using
low energy and rapidly activated adhesion receptors to form transient
metastable adhesions and (b) CTCs stabilize their adhesions to the
endothelial layer with high energy and slowly activated adhesion
receptors. In this methods chapter, we describe these easy-to-implement
quantitative methods using commercially available microfluidic channels.
We detail the use of fast live imaging combined to fine-tuned perfusion
to measure the adhesion potential of CTC depending on flow velocities.
We document how rapidly engaged early metastable adhesion can be
discriminated from slower activated stable adhesion using microfluidics.
Finally, CTC extravasation potential can be assessed within this setup
using long-term cell culture under flow. Altogether, this experimental
pipeline can be adapted to probe the adhesion (to the endothelial layer)
and extravasation potential of any circulating cell.