MBI PhD Oral Defense

Time: 3pm
Date:  Thursday, 20 September 2018
Venue: NUS Faculty of Engineering, E3-06-12

Supervisors: Prof Virgile Viasnoff (Main supervisor), Prof Evelyn Yim (Co-supervisor)

Turning micro-wells into artificial 3D micro-niches with combined biochemical and biophysical cues

by Celine Marie Helene STOECKLIN, Viasnoff Group

Cells in a tissue are residing within an assembly of intertwined chemical and mechanical signals coming from the extracellular matrix, cell–cell interactions and soluble factors. It is this complex and three-dimensional (3D) micro-environment that governs their behavior. Rapid progress has been made in the development of biomimetic culture systems aiming to recapitulate this complexity in vitro. All these tools have greatly advance our understanding of how cells sense their surrounding environment. Moreover, these engineered artificial micro-environments provide good platforms to study biological processes and understand their underlying regulatory mechanisms under highly defined conditions. Whereas a large number of environmental cues can be reconstituted individually and mostly in two-dimension (2D), it remains challenging to control in a single technique any combination of these factors.

In the first part of the thesis, we propose a novel approach to create 3D artificial micro-niches with more than 80 possible combinations of environ- mental factors. Using a UV protein printer and photo-reactive materials, we demonstrate how the layering of polymeric membranes can be used to fabricate micro-niches with complex environmental properties. Our approach enables to bio-functionalized micro-wells in 3D simultaneously with protein patterns, structured hydrogels and topographical features with 1 micrometer precision. 

The second part is dedicated to cell seeding and behavior inside these complex micro-niches. Focusing on single epithelial cell, we demonstrate how fibronectin micro-patterned niches extend the capability to normalize cell internal organization in 3D. We then show that a specific micro-environment mimicking the in vivo conditions can trigger the apico-basal polarization of single hepatocytes.

In the last part, we investigate the potential of our method to create complex micro-niches with multiple cell types at the organoid scale. To explore this topic, we take the human hair follicle as a paradigm. Specifically, the reciprocal epithelial-mesenchymal interaction necessary for hair growth is studied by monitoring the spatial organisation of human primary keratinocytes and dermal papilla cells of the hair follicle inside the micro- niches.

**Please note the examination following the seminar is closed-door**