Bioprinting as a Tool to Evaluate Interactions of Cancerous and Noncancerous Cells

Cancer is becoming one the leading causes of death worldwide, and in particular, breast cancer, which is the second highest cause of cancer death for women. Approximately 12 percent of US women will develop invasive breast cancer, and about 40,000 of US women will die from breast cancer in 2015. With better detection and treatment options, breast cancer death has been decreasing over the past two decades. Despite declining rates in breast cancer death, cancer progression is not well understood. There are many studies focused on cancer, but in situ cancer studies are often hard to reproduce and can even be impractical. There is a demand for in vitro cancer models that imitate the in vivo environment of cancerous cells and tumor development. Numerous models have been developed to better understand normal and cancerous breast tissue. Tissue engineering involves the generation of three-dimensional (3D) tissue structures by seeding cells onto a scaffold so the cells can attach and proliferate into a 3D functional tissue. Unfortunately this approach lacks precise cellular placement and fails to create the intricate and complex environment of normal human tissue. The specific microenvironment has been shown to play a key role in metastatic cell behavior and in determining phenotype and function of mammary cells. Design of a particular 3D arrangement of cells would allow a better understanding of cellular behavior and interactions. One promising technique for tissue formation is biofabrication, which can generate 3D tissues through the delivery of cells and biomaterials layer-by-layer. Biofabrication can precisely arrange cells and create scaffolds with more organization and complexity. Bioprinting is the drop-by-drop deposition of cells and biomaterials. Inkjet printing technology has been used to create bioprinters and is an inexpensive way to print precise patterns of cell and biomaterials with little reduction in cellular viability, with easy pattern modification, and with minimal effect on the substrate. Inkjet bioprinting has great potential for the development of in vitro breast tissue models; the general aim of this thesis was to test the capabilities of inkjet bioprinting for creating in vitro cancer models. The objective of this work was to characterize the interactions of cancerous and noncancerous breast cells through several qualitative and quantitative methods after the cells were printed into lines of varying distances apart, using a modified inkjet printer as a bioprinter. MCF-10a and MCF-7 cells were printed into two opposing lines of varying distances apart onto a collagen coated glass slide, using a bioprinter. To assess the effect of the distance on printed lines of cancer and noncancerous breast cells, several testing methods were proposed, and samples were taken at time points of Day 1 and Day 5 after printing. The results from the collected data lead to several general, key findings. First, the cancerous cells modified the cellular behavior of the noncancerous cells. Second, time played a key role in the performance of the cells, particularly for metabolic activity, and the overall results points towards a change in cellular behavior with a change in distance between lines. Last, the study laid the foundation for potential research to use a bioprinter for in vitro cancer models. Future studies should focus on improvements or alterations to the bioprinter and experimental analyses to enhance findings