Fig. 4

Automated fabrication of the 3D BM niche-like AML model using 3D bioprinting. (A) An in-house developed robotic 3D bioprinting system with a novel quadruple coaxial nozzle design and microfluidic syringe pumps. The quadruple coaxial nozzle for multicellular 3D bioprinting houses a mixing chamber for the peptide hydrogel and PBS buffer and three inlets for different cell types suspended in 1X PBS. (B) A cell viability assessment of KG1a post-printing. Cells were stained with calcein-AM (green, live cells) and ethidium homodimer-1 (red, dead cells; scale bar, 100 μm). (C) Left image: A cell viability assessment of ECs post-printing (day 7). Right image: Immunofluorescence staining using ECs post-printing (green: CD146 surface marker, blue: Dapi; scale bar, 100 μm). (D) Multicellular printing of DiO-labeled KG1a cells (green), DiD-labeled hBM-MSCS (red), and Dil-labeled ECs (yellow/blue). (E) Confocal microscopy images of the printed 3D BM niche-like AML model demonstrating interactions between AML cells and hBM-MSCs (scale bar, 50 μm). Red, hBM-MSCs; green, KG1a cells; blue, nucleus. (F) SEM images of 3D multicellular disease models showing cell-cell and cell-matrix interactions (red arrows)