Assessing angiogenic potential of 3D tumour spheroids for in-vitro co-culture models

Walji, Noosheen 1, 2; Young, Edmond 1, 2

 1. Department of Mechanical and Industrial Engineering, University of Toronto; 2. Institute of Biomaterials and Biomedical Engineering

BACKGROUND: Angiogenesis, or the development of new blood vessels, is a key mechanism in the proliferation of cancer cells and plays an essential role in cancer development. When the tumour reaches a critical size, angiogenesis is induced resulting in the vascularization and subsequent growth of the tumour. There is interest in furthering our understanding of mechanisms associated with tumour-induced angiogenesis and tumour vascularization to better understand cancer development and identify treatment targets. 3D tumour spheroids are an increasingly popular tool for in-vitro cell culture models because they recapitulate key features of the tumour architecture and resulting chemical behaviours. Several spheroid formation methods and culture models have been explored in literature. However, the characteristics of a formed spheroid in culture, and the potential of the spheroid to induce angiogenesis, have not been studied extensively, especially over different timepoints.

METHODS: In this work, an assessment of the angiogenic potential of lung cancer (A549) and breast cancer (MCF-7) spheroids is conducted by measuring areas of hypoxia, necrosis, and proliferation over the span of one week in culture. Spheroids are also assessed for the production of vascular endothelial growth factor (VEGF), a key signaling molecule in angiogenesis. A microfluidic in vitro co-culture model is implemented to observe tumour spheroid interactions with human umbilical vein endothelial cells (HUVECs).

RESULTS: Spheroids in monoculture for different durations (prior to cell culture) demonstrate variations in angiogenic potential, where corresponding variations in angiogenic behaviour can be observed in the co-culture.

SIGNIFICANCE: This assessment will allow spheroid characteristics to be taken into consideration when evaluating nutrient and chemical gradients involved in tumour-vascularization models, as well as the corresponding drug efficacy in studies where in-vitro drug screening is of interest.