This research developed methods for culturing self-assembling capillaries in an injectable gel as a potential method for vascularizing tissue-on-a-chip models to mimic physiological drug delivery. Additionally, a mathematical model was developed as a tool for understanding nutrient delivery and comparison of potential delivery systems. Organs-on-a-chip provide novel platforms for studying biology and physiology in 3D, allow exploration of tissue engineering on a manageable scale, and serve as models for drug screening and drug-delivery testing. Methods were first developed for co-culture of endothelial cells and fibroblasts (3T3s or HDFs) in 2D, evaluating culture time, seeding density and ratio of HUVECs and fibroblasts, and immunostaining with a HUVEC-specific marker. Cells formed large sheets with no signs of vessel formation in 2D; therefore, the setup was translated to 3D culture to further induce stress and release of angiogenetic factors, using fibrin gel to suspend cells in 3D. After 9 days of culture, HUVECs had extensive network formation with a high degree of complexity in the experimental cell ratios (especially with 5:1 HUVECs:HDFs). Therefore, these parameters can be used as a starting point for further development of vascularized tissue constructs. A mathematical model was also successfully developed to assess the impact of cell concentration, consumption, and mode of nutrient delivery on 3D cellular constructs which can be used to predict the spatial distribution of glucose over time. Although the model shows flow introduced through a device is sufficient to maintain nutrient levels for cell growth, developing perfusable capillaries is still a critical part of creating physiologically representative tissues.