A Light Sensitive Hyaluronic Acid-based Hydrogel for 3D Culturing, Differentiation, and Harvesting of Mesenchymal Stromal Cells

Hydrogels derived from natural sources are commonly used for 3D cell culturing due to their favourable interactions with cells. However, these biomaterials (e.g. Matrigel) suffer from variations in composition, limited mechanical tunability, the presence of xenogenic components and difficulties of cell retrieval. Semi-synthetic hydrogels are emerging to address these limitations, making these attractive for drug delivery and tissue engineering. Here, we describe a hydrogel platform based on hyaluronic acid (HA) modified by (1R,8S,9S)-bicycle[6.1.0]non-4-yn-9-ylmethanol (BCN) and a cross-linker composed of light sensitive o-nitrobenzyl moieties and polyethylene glycol (PEG) chains terminating in azides. The two components can undergo strain-promoted azide-alkyne cycloaddition (SPAAC) resulting in rapid gel formation. The stiffness of the hydrogel can be modulated by varying the crosslinker ratio and multi-functionalizing is possible by the incorporation of chemical cues modified by an azide. The fast hydrogelation enables easy encapsulation of cells and harvesting with preservation of viability is possible be short exposure to UV light. Moreover, it is demonstrated that visible light (405 nm) can soften the hydrogel resulting in phenotypical changes of human Mesenchymal Stromal Cells (hMSCs) co-cultured with endothelial colony-forming cells (ECFCs) with high viability. Our findings highlight that the photosensitive HA-based hydrogel provides a versatile and biocompatible platform for cell culture and tissue engineering applications, offering advantages over traditional 3D cell culturing platforms.