Cancer Cell Migration in a Three-Dimensional Microfluidic Platform

Cancer Cell Migration in a Three-dimensional Microfluidic Platform

Metastasis, the migration and spread of tumor cells from a primary tumor to other areas of the body, is the most common cause of cancer patients' death. Knowledge of cancer cell migration is vital to cancer diagnostics and treatment. The conventional in vitro cell culture, which uses flat plastic substrates under static condition, does not recapitulate the characteristics of in vivo cellular microenvironments where cells reside in a three-dimensional (3-D) extracellular matrix (ECM) and are regulated by the characteristics including ECM mechanical properties and interstitial flows. To this regard, it is essential to develop a 3-D cell culture platform with a fluidic flow to study cancer cell migration. Myosin II, involved in cells ability to migrate and remodel 3-D matrix, is of particular interest. Therefore, we engineered a 3-D microfluidic platform to study cancer cell migration and examined the role of Myosin II in cancer cell migration.

 A microfluidic chip was fabricated by using photolithography and assembled by applying a microtransfer assembly technique developed. The cells, including metastatic breast cancer cell line (MDA-MB-231 cells) and Myosin IIA and IIB knockdown (KD) MDA-MB-231 cell lines were embedded into Type I rat-tail collagen and then injected into the microfluidic chip.

In the 3-D matrix the cells displayed distinct phenotype compared to the 2-D configurations. On 2-D gels, Myosin IIA knockdown cells had altered actin organization and Myosin IIB knockdown cells exhibited a more irregular shape with prominent stress fibers, compared to the parental control cells. Differently, in 3-D matrix, the parental MDA-MB-231 cells had pyramidal cell bodies with multiple projections. Interestingly, Myosin IIA knockdown cells had rounded cell bodies with highly branched and elongated projections in all directions while IIB knockdown cells where elongated with fewer projections. Moreover, Myosin II isoforms played a significant role in cancer cell migration.  Loss of Myosin IIA and IIB reduced migratory velocity and altered displacement, and overall track length compared to the parental MDA-MB-231 cells. Blebbistatin (a Myosin II inhibitor) treated MDA-MB-231 also modified migratory velocity, displacement, and track total length. Furthermore, introduction of the fluidic flow had influence on migratory direction and displacement of these cells.

Our study showed that the cancer cells had different migratory patterns in both 2-D and 3-D configurations and Myosin II isoforms played a distinct role in MDA-MB-231 cell migration. Moreover, a 3-D, dynamic cell culture platform mimics the in vivo microenvironment and will provide a useful tool for cancer metastasis research.