Perivascular cell dynamics during wrapping‐and‐tapping anastomosis

Abstract

Rapid blood perfusion is critical for post‐implantation survival of thick, prevascularized grafts or bioartificial tissues. In an earlier study, we showed that implanted vascular networks anastomose with host vessels through a process of “wrapping and tapping” between the engrafted endothelial cells (ECs) and the host vasculature. At the host‐implant interface, implanted ECs wrap around nearby host vessels, cause vessel wall reorganization and displace the underlying host endothelium, diverting blood flow to the implanted vascular network. The process is facilitated by high levels of matrix metalloproteinase‐14 and matrix metalloproteinase‐9 produced by the wrapping ECs.During this process, most host vessels within the brain and implant are fortified with NG‐2‐positive pericytes. In contrast, desmin‐positive pericytes are associated with mature vessels, but not angiogenic host vessels in the gel. Surprisingly, aSMA‐positive perivascular cells are not only associated with large, mature vessels in the brain, but also with the developing HUVEC plexus and wrapped host segments. Thus, aSMA positive stromal cells are involved in formation of the nascent network and desmin staining is associated with of the maturation of the engraft vessels.