Micropuncture and granular hydrogel scaffolds to surgically bioengineer a perfusable and stably patterned microvasculature.

Vascularization of implanted biomaterials is critical to reconstructive surgery and tissue engineering. Ultimately, the goal is to promote a rapidly perfusable hierarchical microvasculature that persists with time and can meet underlying tissue needs. We have previously shown that using a microsurgical technique, termed micropuncture (MP), in combination with porous granular hydrogel scaffolds (GHS) fabricated via interlinking hydrogel microparticles (microgels) results in a rapidly perfusable patterned microvasculature. However, whether this engineered microvasculature remains stable at longer time points remains unknown. Here, we combine MP with GHS and compare overall microvascular architecture and phenotype along with the evolving cellular landscape over a 28 day period. We demonstrate perfusable patterned microvascular stability in our MP + GHS model that occurs alongside a sustained rise in endothelial cell and macrophage recruitment. Specifically, MP yields a significant rise in M2 macrophages between the 7 and 28 day time points, suggesting ongoing microvascular remodeling, even in the presence of early pericyte stabilization. With time, the GHS microvasculature acquires a relatively equivalent arterial and venous morphology, as assessed through Ephrin-B2 and EphB4 quantification. Finally, angiography at 28 days shows that MP + GHS is associated with more perfusable microvascular loops when compared with MP + Bulk (nonporous) scaffolds. Hence, our surgically bioengineered microvasculature offers a unique opportunity to sustainably and precisely control biomaterial vascularization and ultimately advance the fields of reconstructive surgery and tissue engineering.