Ca2+ Mediates the Adhesion of Breast Cancer Cells in Self-Assembled Multifunctional Microfluidic Chip Prepared with Carbohydrate Beads

G.      Simone; G.      Perozziello

Abstract

Calcium has been demonstrated to have a fundamental role in cell-cell recognition mediating the carbohydrate- carbohydrate and the protein-carbohydrate interactions. A self assembled multifunctional microfluidic array has been used to exploit the interactions between breast tumor cells and an engineered surface. Engineering concerns the topology of the surface, since microbeads have been used to increase the micro roughness of the surface, the biochemistry, since the microbeads are conjugated by carbohydrates before being integrated inside the microfluidic chamber. Microfluidic environment permits to control parameters such as the shear force and the velocity and mimicking the microenvironment surrounding the cells. To this end it is extremely important to investigate the role of calcium in cell carbohydrate interactions in a microfluidic environment. Investigation has been performed varying the calcium concentration of cell media and the fluidic condition. Breast tumor cells have been used. Static and dynamic experiments have been performed. Static experiments have shown that differences in the cell adhesion behavior are only detectable when dealing with calcium free buffer, whilst the results of adhesion in correspondence of different carbohydrates have been lost when dealing with calcium enriched media. Adhesion of glucose is independent on the composition of the buffer. At 3000 μl sec-1 60 and 80% of adherent cells have been counted in according to the free and enriched calcium media. The trend of the results from the dynamic experiments is not affected by the presence of calcium, and three different conditions can be identified. In particular, between 10 and 15 μl min-1 they adhere and start roll on the substrate at high flow rate. We assume that during the first seconds calcium is not able to drive the interaction between carbohydrates and cells and hydrodynamic phenomena, the balance between shear force and velocity, play the most important role.

Keywords: Carbohydrates, immobilization, calcium, tumor, shear stress, galacto-sylceramide I3 sulfate, x-ray crystallography, NMR, Electros-pray ionization mass spectrometry, HIV-1, Spherotech, Methacryloyl hydrazide, 2,2azobisisobutyronitrile, AIBN