Meniscus induced self organization of multiple deep concave wells in a microchannel for embryoid bodies generation.

Embryonic stem cells (ESCs) have attracted great interest in the fields of tissue engineering, regenerative medicine, and organogenesis for their pluripotency and ability to self-renew. ESC aggregation, which produces an embryoid body (EB), has been widely utilized as a trigger of in vitro directed differentiation. In this paper, we propose a novel method for constructing large numbers of deep concave wells in PDMS microfluidic chips using the meniscus induced by the surface tension of a liquid PDMS prepolymer, and applied this chip for the mass production of uniform sized EBs. To investigate if the microenvironment in the deep concave well is suitable for ES cells, the oxygen diffusion to the deep concave well was analyzed by CFD simulation. Murine EBs were successfully formed in the deep concave wells without loss of cells and laborious careful intervention to refresh culture media. The size of the EBs was uniform, and retrieving of EBs was done just by flipping over the chip. All the processes including EB formation and harvest are easy and safe to cells, and their viability after completion of all processes was over 95%. The basic properties of the EBs were generated and their capacity to differentiate into 3 germ layers was investigated by analyzing the gene expression profile. The harvested EBs were found to differentiate into cardiac cells and neurons, and neurofilaments formed branches of elongated extensions more than 1.0 mm in length.