Mechanisms and Application of Micropunctured Induced Angiogenesis for the Rapid Perfusion of Intraoperative Bioprinted Flaps

PROJECT SUMMARY/ABSTRACT Advances have allowed for the in vitro creation of thin vascularized replacement grafts but lack of a continuous and anastomosable vasculature limits translation and scale-up of size. There is little knowledge about the utility of surgical approaches in facilitating prompt inosculation of implanted engineered tissues. Our long-term goal is to develop surgical strategies which augment the vascular integration of thick engineered flaps; which would offer more clinical relevance. The objective of this proposal is to define the mechanisms and impact of a coordinated surgical and additive manufacturing approach for the rapid vascularization of an engineered adipose flap, which would be applicable for soft tissue reconstruction. We have developed an innovative microsurgical tactic, termed ?vascular micropuncture?, which increases the angiogenic capabilities of the rat recipient vasculature in order to quickly perfuse an adjacently placed un-anastomosable thin engineered graft. This results in graft perfusion within 24 hours and a doubling of neovascularization. If combined with standard vascular interposition conduits (e.g. saphenous vein), which can be used to lengthen the recipient pedicle, it offers an easily translatable approach for thick flap engineering. Our central hypothesis is that vascular micropuncture and lengthening of the recipient vasculature can enable direct inosculation and rapid perfusion of a thick adipose flap that is intraoperatively bioprinted with adipocyte/endothelial progenitor cell spheroids. The rationale is that completion of these studies will reveal how to best optimize complementary tactics for the inosculation of concurrently engineered in situ flaps. Our central hypothesis will be tested by three specific aims: 1) Demonstrate that micropuncture induces angiogenesis by allowing for immediate monocyte/macrophage extravasation; 2) High-throughput bioprinting and in vitro testing of a hypoxia-resistant vascularized adipose graft; 3) Coordinated in situ thick flap generation and surgically induced rapid perfusion. We will pursue these aims using novel combinatorial techniques from both the surgical and engineering sciences, including recently developed microsurgical and aspiration assisted bioprinting approaches. This proposed research is significant because it will integrate these advances to intraoperatively assemble and rapidly perfuse a thick engineered flap; a noteworthy advance from the often-described thin engineered graft. The expected outcome is that mechanisms of micropunctured induced angiogenesis will be identified and experimental techniques for augmenting engineered tissue inosculation will be determined. These results will have a positive impact by laying the foundation in developing new and translatable reconstructive approaches for large volume soft tissue loss.