Freestanding hierarchical vascular structures engineered from ice.

The ability to engineer a synthetic hierarchical vascular network is one of the most demanding and unaddressed challenges in tissue engineering and regenerative medicine. A material that is both structurally rigid and biocompatible is needed to fabricate freestanding hierarchical vascular structures with defined dimensions and geometry. This is particularly important for creating commercially viable and easily suturable synthetic vasculature. Here, we present the surprising discovery that ice is a versatile material which satisfies these requirements. We demonstrate utilizing ice as a sacrificial scaffold, onto which a diverse range of materials were coated, including tropoelastin, polycaprolactone (PCL), silk, and polydimethylsiloxane (PDMS). We present ice facilitating the fabrication of freestanding hierarchical vascular structures with variable lumen dimensions, and validate the vascular application of these vessels by demonstrating their mechanical tunability, biocompatibility, and permeability to nutrient diffusion. This adaptable technology delivers engineered synthetic vasculature and has potential wider applications encompassing tissue engineering bespoke structures.