Biophysical regulations in neural development

Abstract

During neural development, in synergy with widely studied biochemical signals, biophysical cues cooperate in the regulation of cell behaviour. In addition to gene and protein expression, recent studies have highlighted the significance of epigenetic modulation on cell fate. Although it is known that extracellular biophysical cues can affect important cellular events, only a few studies have systematically examined their effects on stage-specific developmental patterns and neuronal maturation, particularly in humans. Moreover, very few of them have further linked biophysical modulations to epigenetic mechanisms. This project aims to create a new bioengineered platform incorporating conductive materials with topographical cues, specifically microgrooves, to examine the combinatorial effects of surface topography and electrical stimulation on clinically relevant neuronal populations derived from human pluripotent stem cells (hPSCs). The microgrooved platform and its synergistic effects with electrical stimulation can promote neuronal differentiation. For the first time, an increase in epigenetic markers associated with stemness and differentiation, such as AcH3, AcH4, and H3K9me3, was reported on the microgrooves and after electrical stimulation. Using state-of-the-art focused ion beam scanning electron microscopy, the observed epigenetic changes and corresponding nuclear morphology were examined in high resolution. Moreover, in parallel with topography-dependent epigenetic modulations, a new mechanism was proposed –namely that microgrooves can modulate Notch signalling through geometric segregation. Finally, a new tissue-engineered scaffold based on electrospun serum albumin (SA) was developed with the incorporation of both biochemical and biophysical stimuli. This served as a functional growth factor release construct and positively influenced neuronal differentiation and maturation with electrical stimulation. The thesis presents a systematic examination of cellular behaviour in response to biophysical stimuli, including surface topography and electrical stimuli. Together, novel mechanisms associated with epigenetics and signalling pathways as well as the new SA based scaffold, can advance fundamental research in neuroscience and future translational applications.