Microchamber design, fabrication, and characterization. (A) A single microchamber consisted of a central well connected to 2 side chambers via diffusion channels, and access ports to each of the compartments. Fluid replacement is performed via passive pumping using a micropipette (Section X-X). The central well was designed to have low wall shear stress at the bottom to retain settled nonadherent MM cells. Side chambers were used for experiments involving BMSCs in coculture with MM cells (Section Y-Y, inset). Scale bar represents 3 mm. (B) A single device consisted of a 3 × 4 array of microchambers on a 75 × 50-mm slide. Scale bar represents 10 mm. (C) Priming of the microchamber with 70% ethanol containing red food coloring dye. Scale bar represents 3 mm. (D) Characterization of the retention of suspension cells in microchambers. Fraction of retained cells, after 25 VRs of 8 μL per VR into the central well, increased with increasing culture time, up to 99% retention for 16 hours of culture before VRs.