Design and surface modification of a microfluidic chip for intercellular interactions research during space flight

Intercellular interactions widely exist in multicellular organisms. The exposure of astronaut's body to space environment results in a series of biological effects including intercellular interactions. However, these interactions have not been studied extensively in space because of the difficulties faced in performing such experiments in the space. To solve this problem, we have designed a co-culture microfluidic chip for studying intercellular interactions and provides an effectively dynamic co-culture method to both adherent cells and suspension cells. Its structure consists of two cell chambers which are divided by polycarbonate semipermeable membrane. The membrane is permeable to signal molecules which are secreted by cells but it is impermeable to the cells itself. Each cell chamber is divided by bolting silk. This results in a control of flow shear stress exerted on the cells and it also results in trapping the suspended cells. As surface property of the base of any microfluidic chip is important, therefore, we optimized a surface modification strategy using MTS assays and water contact angle test. The results show that optimum surface modification strategy is using air plasma treated polystyrene surface for 90s. Moreover, the contact angle recovery after plasma treatment indicated that the co-culture microfluidic chip should be seeded within 6 days after surface modification. Our results show that a successful dynamic cell co-culture was achieved using this design. We conclude that this co-culture microfluidic chip can be a valuable tool for investigating intercellular interactions in space as it can be operated automatically during a space flight.