Structurally decoupled hyaluronic acid hydrogels for studying matrix metalloproteinase-mediated invasion of metastatic breast cancer cells

In recent years, polymeric hydrogels have been employed to investigate cancer cell-extracellular matrix (ECM) interactions in vitro. In the context of breast cancer, cancer cells are known to degrade the ECM using matrixmetalloproteinases (MMPs) to support invasion resulting in disease progression. Polymeric hydrogels incorporating MMP-cleavable peptides have been employed to study cancer cell invasion, however, the approaches employed to incorporate these peptides often change other hydrogel properties. This underscores the need for decoupling hydrogel properties while incorporating MMP-cleavable peptides. Herein, we report structurally decoupled hyaluronic acid (HA) hydrogels formulated using varying ratios of a biologically sensitive MMPcleavable peptide and an insensitive counterpart (Dithiothreitol (DTT) or polyethylene glycol dithiol (PEGDT)) to study MMP-mediated metastatic breast cancer cell invasion. Rheological, swelling ratio, estimated mesh size, and permeability measurements showed similar mechanical and physical properties for hydrogels crosslinked with different DTT (or PEGDT)/MMP ratios. However, their degradation rate in the presence of collagenase correlated with the ratio of MMP-cleavable peptide. Encapsulated metastatic breast cancer spheroids in HA hydrogels with MMP sensitivity exhibited increased invasiveness compared to those without MMP sensitivity after 14 days of culture. Overall, such structurally decoupled HA hydrogels provide a platform to study MMP-mediated breast cancer cell invasion in vitro.