Advances in dynamic and responsive materials for intestinal organoid culture

Methods for culturing intestinal organoids (IOs) in biologically relevant, but defined matrices are increasingly needed to expand and differentiate intestinal stem cells (ISCs), study organoid development and physiology, and to grow tissues that can be transplanted in humans While Matrigel has been the paradigm for IO culture, evidence and intuition suggest that batch-to-batch variability and the resulting heterogeneity in IO structure make it more complex to understand structure-function relationships and scale up production of predictable organoid structures. As a result, many researchers are realizing the advantages of synthetic hydrogels as a means of creating custom 3D microenvironments with highly controlled chemical, biological and physical cues. Further, the native extracellular matrix (ECM) is far from static, so synthetic ECM mimics must also be dynamic to direct complex cellular behavior. This talk will illustrate several examples of recent advances photoresponsive biomaterial chemistries for growth of intestinal organoids with defined structures and demonstrate how one can dynamically control biochemical and biophysical properties through orthogonal, photochemical click reaction mechanisms. One example will illustrate the design of photoadaptable, allyl sulfide functionalized poly(ethylene glycol) hydrogels for the growth of IOs, and the subsequent application of photopatterned light to locally alter epithelial curvature, initiate symmetry breaking events, and ultimately direct cell fate. In more recent work, we discovered noticeable changes in the nuclear envelope architecture and composition as ISCs differentiate, which is also observed in vivo. Moreover, variations in initial epithelial shape can dictate nuclear forces, ultimately leading to differences in cell fate, implicating that the nuclei might play an active role in the process of crypt formation and differentiation. Finally, these studies are then complemented by recent development of new materials and methods for expansion microscopy, which enable optical clearance and super-resolution imaging of intestinal organoids and their ECM in 3D matrices.