A microfluidic traps system supporting prolonged culture of human embryonic stem cells aggregates.

The unlimited proliferative and differentiative capacities of embryonic stem cells (ESCs) are tightly regulated by their microenvironment. Local concentrations of soluble factors, cell-cell interactions and extracellular matrix signaling are just a few variables that influence ESC fate. A common method employed to induce ESC differentiation involves the formation of cell aggregates called embryoid bodies (EBs), which recapitulate early stages of embryonic development. EBs are normally formed in suspension cultures, producing heterogeneously shaped and sized aggregates. The present study demonstrates the usage of a microfluidic traps system which supports prolonged EB culturing. The traps are uniquely designed to facilitate cell capture and aggregation while offering efficient gas/nutrients exchange. A finite element simulation is presented with emphasis on several aspects critical to appropriate design of such bioreactors for ESC culture. Finally, human ESC, mouse Nestin-GFP ESC and OCT4-EGFP ESCs were cultured using this technique and demonstrated extended viability for more than 5 days. In addition, EBs developed and maintained a polarized differentiation pattern, possibly as a result of the nutrient gradients imposed by the traps bioreactor. The novel microbioreactor presented here can enhance future embryogenesis research by offering tight control of culturing conditions.