Exploring the potential of Inkjet printing for the fabrication of tissue test systems

Animal models and two-dimensional assays involved in drug testing, vaccine development and basic scientific discovery are not an accurate representation of the human body; hence there is a need to develop new bench top methodologies which are better suited to yield information about in vivo behavior. There is a paucity of reliable in vitro-derived information regarding the reasons for the cause and progression of diseases. These concerns have lead to the development of three-dimensional systems which can facilitate improved understanding of disease etiology and also can bridge the path to the clinic. The long term goal, beyond the scope of this project is to develop a three-dimensional breast test system which contains different cell types in a spatial arrangement mimicking that seen in the mammary gland. The primary goal of this project is to standardize a bioprinter and to analyze cellular interactions, the results of which will be used to inform the construction of three-dimensional test systems. D1 cells were printed onto three different substrates, in different concentrations and time intervals, to study the number of cells ejected per drop. The results indicated a consistent rise in the number of cells per drop with time and cell concentration, the maximum obtained at a concentration of 8 million cells/mL. Subsequently, D1 cells and NMuMGs were printed and pipetted in specific patterns to analyze the effect of the NMuMGs on the differentiation of D1s. The substrates were chitosan-gelatin-coated, collagen gel-coated and polystyrene slides. At the end of 16 days, the cells were tested for the presence of specific genes and lipids. The lipid analysis data did not indicate significant differences between the samples that were printed but showed marginally higher lipid production in the presence of NMuMGs in the pipetted group. The semi-quantitative gene expression data indicated that a change in intercellular distance between mammary epithelial cells and murine bone marrow stromal cells influences adipogenesis, with the highest gene expression of aP-2 when the two cell types were furthest apart