Development of a Synthetic Hydrogel to Foster Microvascularization of an Endometriosis Microphysiological System

The ascent of novel alternative methods (NAMs) in drug development spotlights the dual needs for improved biological fidelity to in vivo along with reproducibility, especially in regulatory applications. The need for pre-clinical models of patient-derived endometriosis lesions motivates development of a vascularizable completely synthetic extracellular matrix (v-CS-ECM) that supports morphogenesis of perfusable microvasculature in a microfluidic device, in the context of relevant lesion cells. This paper describes v-CS-ECM, a peptide-modified polyethylene glycol-based hydrogel crosslinked with a cell-degradable peptide that achieves these dual goals. Vessels form by morphogenesis after the liquid v-CS-ECM precursor, containing endothelial cells and fibroblasts, is injected into the tissue compartment to encapsulate cells. Vessel formation is influenced by ECM biochemical and biophysical properties, source of vascular cells, and microphysiological system (MPS) operating conditions. The v-CS-ECM also supports co-culture of endometrial epithelial organoids (EEOs) and fibroblasts, and formation of microvascularized endometriosis lesion-like structures when all cell types are co-encapsulated in a microfluidic device with constant flow. Hence, v-CS-ECM overcomes limitations of reproducibility and biological function inherent in the fibrin-based ECM typically employed for microvascular morphogenesis, as well as Matrigel for organoid culture, thus offering promise for NAMs evaluating endometriosis drugs in the preclinical setting.