Microfluidic device capable of medium recirculation for non-adherent cellculture

We present a microfluidicdevice designed for maintenance and culture of non-adherent mammalian cells, which enables both recirculation andrefreshing of medium, as well as easy harvesting of cells from the device. We demonstrate fabrication of a novel microfluidic device utilizing Brailleperfusion for peristaltic fluidflow to enable switching between recirculation and refresh flow modes. Utilizing fluid flow simulations and the humanpromyelocytic leukemia cellline, HL-60, non-adherent cells, we demonstrate the utility of this RECIR-REFRESH device. With computer simulations, weprofiled fluid flow andconcentration gradients of autocrine factors and found that the geometry of the cell culture well plays a key role incell entrapping andretaining autocrine and soluble factors. We subjected HL-60 cells, in the device, to a treatment regimen of 1.25% dimethylsulfoxide, every other day, toprovoke differentiation and measured subsequent expression of CD11b on day 2 and day 4 and tumornecrosis factor-alpha (TNF-α) on day 4. Our findings display perfusion sensitive CD11b expression,but not TNF-α build-up, by day 4 of culture, with a 1:1 ratio of recirculation to refreshflow yielding the greatestincrease in CD11b levels. RECIR-REFRESH facilitates programmable levels of cell differentiation in a HL-60non-adherent cell populationand can be expanded to other types of non-adherent cells such as hematopoietic stem cells.