Laminar Flow And Liquid Membrane Aided Cell Patterning To Study Endothelial And Breast Cancer Cell Interaction In Vitro

Metastasis, rather than primary tumor, is responsible for most breast cancer deaths.Metastasis is a multi-stage process involving cancer cell motility, intravasation, transit in theblood or lymph, extravasation and growth at a new site. Tumor microenvironment is the placethat metastasis happens. The cross-talk between tumor cells and vasculature endothelium intumor microenvironment is critical because this interaction plays an important role in manymetastasis courses including intra-and extravasation as well as angiogenesis.Various of methods have been developed to observe the interaction of tumor cells andendothelial cells in vitro. The classic Boyden/Transwell chamber has been widely utilized inthis field. However, cumbersome staining procedures for counting the cells remaining in themembrane gaps and incompatible real-time observation of cells have limited furtherpopularity of this method. Spheroids, which are microscale, spherical cell clusters formed byself-assembly, are one of the most common and versatile methods of culturing cells in threedimensional condition. However, this approach exhibits difficulties for distributing differentcells in respective regions and accurately controlling the spatial and temporal parameters.Thus, the development of in vitro coculture systems that not only recapitulate aspects of theunique tumor microenvironment but also allow spatially and temporally controlledobservation of tumor-endothelial interaction has become an emergent field in cancer research.We developed a microfluidic cell coculture platform that utilized laminar flow and liquidmembrane to pattern two kinds of cell populations in their respective but related positions.The platform is capable of both two dimensional and three dimensional cell coculture andreal-time observation of cell-cell interactions. The mass transportation and distribution in thedevice was quantitatively assessed to prove that this constructed system could satisfyinteractions of non-contact coculture cells through soluble factor. The experimental resultsobtained from two dimensional culture proved that HUVEC-C could promote motility ofMDA-MB231by secrete soluble factors and this influence was chemotaxis. In addition, wecompleted three dimensional culture using the same device. In this environment, both of thecells exhibited different morphological changes compared with two dimensional condition.HUVEC-C enhanced the invasiveness of MDA-MB231growing out of long protrusions,correspondingly, MDA-MB231drastically affected endothelial morphogenesis showing pre-capillary sprout formation，which is an early mark of cancer progression. We believe thatthis versatile microfluidic platform will facilitate the study of cell-cell interaction underlyingthe early stage of tumor angiogenesis as well as the development of new therapies for treatingcancer and other angiogenesis-dependent diseases.