Spatial patterns of biomolecules play a central role in a range of biological processes, from embryogenesis to cancer development. Although some progress has been made in recent years, most current engineered platforms lack the spatial resolution to accurately model these systems. The ability to exert control over the local activation of signalling pathways that cells experience in vitro could facilitate investigations into developmental processes, as well as disease and cancer progression, and could lessen the burden of animal research. To this end, this thesis describes efforts to manufacture a novel material system that can present a spatially patterned interface to cells in culture. By leveraging inkjet printing on nanotopographical substrates, the behaviour of cells can be influenced both biochemically and physically. A range of bio-inks were investigated in this work, from proteins to small molecule pathway activators and inhibitors.
Through the printing of Shh protein gradients, a spinal cord-on-a-chip model was developed, with motor neuron and other progenitor cell types being generated from mouse embryonic stem cells. A range of transcription factors verified the presence of specific ventral subtypes from the neural tube, and quantitative analysis of microscopy images was used to visualise the reproducibility of the differentiation induced in cells on printed patterns.
The platform was also utilised in preliminary studies into targeted Wnt pathway activation for cancer investigations. A number of candidate cell lines were screened, with similar image analysis methods being utilised to visualise the role that printed bio-inks played in a range of cell behaviours. The printed Wnt gradients were seen to influence cell density considerably, and also showed location-dependent levels of pathway activation.
It is hoped that this approach may encourage more emphasis on spatial patterning in materials design in the future, to enhance the capabilities of bioengineered systems for cell interfacing applications.