Spatial Patterning of Molecular Cues and Vascular Cells in Fully Integrated Hydrogel Channels via Interfacial Bioorthogonal Crosslinking.

Fully integrated hydrogel channels were fabricated via interfacial bioorthogonal crosslinking - a diffusion-controlled method for the creation and patterning of synthetic matrices based on the rapid bioorthogonal reaction between s-tetrazines (Tz) and trans-cyclooctene (TCO) dienophiles. Injecting an aqueous solution of a bisTCO crosslinker into a reservoir of tetrazine-modified hyaluronic acid (HA-Tz), while simultaneously drawing the syringe needle through the reservoir, yielded a crosslinked hydrogel channel that was mechanically robust. Fluorescent tags and biochemical signals were spatially patterned in the channel wall through time-dependent perfusion of TCO-conjugated molecules into the lumen of the channel. Different cell populations were spatially encapsulated in the channel wall via temporal alteration of cell populations in the HA-Tz reservoir. The interfacial approach enabled spatial patterning of vascular cells, including human abdominal aorta endothelial cells, aortic vascular smooth muscle cells, and human aortic adventitial fibroblasts, into the hydrogel channels with high viability and proper morphology in the anatomical order found in human arteries. The bioorthogonal platform does not rely on external triggers and represents a first step towards the engineering of functional and implantable arteries.