Modulation of hydrogel biophysical properties using photoadaptable chemistry improves formation of intestinal organoids*

There is increasing interest to develop well-defined platforms for organoid growth and expansion. It is known that organoid formation from single intestinal stem cells (ISCs) in synthetic hydrogels is influenced by matrix stiffness and can be initiated by hydrogel degradation. Understanding these forces is key to improving efficiency of organoid growth. We use the adaptable allyl sulfide (AS) photochemistry to tune hydrogel biophysical properties through on demand network reorganization. We show that reorganization is dependent on the protonation state of a soluble, monofunctional thiol species. The rate of degradation can therefore be tailored by controlling the thiol pKa or the solution pH. This understanding then guides the selection of conditions that allow for more rapid degradation. Formed using a biorthogonal conjugation reaction, the AS hydrogels support organoid growth from ISCs, which show maintenance of stem cell markers. Intermittent light exposure will be applied in situ to tune the modulus of cell laden hydrogels and the resulting influence on growth, morphology, and presentation of mechanosensitive biochemical markers will be assessed. This understanding can be leveraged to optimize growth of colonies for development of intestinal organoids.