Engineered microvascular basement membrane mimetic for real-time neutrophil tracking in the microvascular wall

The microvascular basement membrane (mvBM) is crucial in maintaining vascular integrity and function and, therefore, key to the health of major organs. However, the complex nature and the intricate interplay of biochemical and biomechanical factors that regulate the mvBM functional dynamics make it difficult to study. Here, we present a novel and highly tunable in vitro model of the human mvBM, enabling a bottom-up approach to assemble a composite model of the microvascular wall and explore microvascular dynamics and interactions with circulating neutrophils in real time. An electrospun polyethylene glycol (PEG)-based fibrillar network mimics the mvBM with adjustable nanofiber diameter, orientation, and density. The fidelity of the model to the human mvBM's topography and mechanics was verified through second harmonic generation imaging and atomic force microscopy. PEG was functionalized with bioactive moieties to enable endothelial cell (EC) and pericyte (PC) attachment, through which neutrophil interactions with the microvascular wall model were observed. The model, coupled with 4D microscopy, revealed nuanced and dynamic neutrophil behavior when interacting with the microvascular wall, demonstrating its utility in characterizing cell-cell interactions. As such, the model can be employed in the exploration of inflammatory and microvascular-related diseases. Therefore, this innovative approach represents a significant advancement in vascular biology research, holding profound implications for understanding mvBM dynamics in both health and disease.