Biofabrication of cancer microenvironment mimics by inkjet printing

Drop-on-demand inkjet printing has opened new opportunities to develop faster, smaller and cheaper biofabrication methods. In this study drop-on-demand piezo inkjet technique was utilized to fabricate miniaturized and well-defined scaffolds. These scaffolds could serve as useful tools to study the interactions of cancer cells in their microenvironment in tissues and in particular, to investigate the effect of protein gradients in the ECM (extracellular matrix) on cellular function and morphogenesis. A miniaturized array consisting of 36 different scaffold spots, which all had the same volume, but contained varying amounts of ECM proteins; collagen, type IV and laminin were printed on microscope slide. The formation of protein gradient was studied by fluorescence and bright field microscopy, and fluorescence scanning. Fluorescence intensities increased nearly linearly with the increase of laminin and collagen concentrations providing direct evidence that protein gradients were formed in the spots. Higher fluorescence intensities of both laminin and collagen in the periphery of the printed spots indicated that the protein concentrations were slightly bigger on the edges of the spots than in the center due to evaporation of printed spots prior to gel formation, but otherwise the mixing was fairly uniform. Results show that inkjet printing is a versatile method to fabricate well-defined and reproducible hydrogel based scaffolds and it can easily be utilized to study cell-matrix interactions implicated in cancer development.