106. Microsurgery-assisted Bioprinting: A Synergistic Approach to Scaffold Vascularization

PURPOSE: Surgeons are tasked with correcting tissue loss resulting from trauma or oncologic resection. Intraoperative bioprinting (IOB) of scaffolds to replace these defects represents the next era of reconstructive surgery. Success of these scaffolds depends on rapid vascularization for scaffold integration. This vascularization can be aided with endothelial cell-seeding technology. We have described a microsurgical approach to rapidly vascularize an adjacently placed scaffold. In micropuncture (MP), the recipient blood vessel wall is precisely disrupted to provide an immediate route for cell extravasation. Here we compare MP vs control samples in a collagen-based scaffold (“bioink”) as compared to a bioink scaffold seeded with rat aortic endothelial cells (RAOEC), hypothesizing that both MP and RAOEC will augment scaffold vascularization. METHODS: MP was applied to rat femoral vessels on one hindlimb while the other served as a non-MP control. An extrusion bioprinter deposited either bioink or bioink+RAOEC directly over the vessels. On POD 10 the animals underwent fluorescence angiography. Samples were analyzed with whole mount angiography and histology. CD31 was used as a marker for endothelial cells. Vascular metrics were assessed with artificial intelligence. RESULTS: There was a significant increase in vessel surface area in each group as compared to the bioink control, with the greatest increase in the RAOEC+MP group. The addition of MP alone also significantly augmented vascular development. This vascular development was further characterized by architecture, with increased branching and looping in the MP groups and minimal change to average vessel length. CD31 counts confirmed increased endothelial cells in the experimental groups. T-tests were used to deduce statistical significance as compared to the “Bioink Control” group. *Indicates significance as follows: *p<.05; **p<.01; ***p<.001;****p<.0001. CONCLUSION: Here we describe combining microsurgery with IOB as a platform for engineering vascularized tissue. Both MP and cell seeding are feasible and have pro-angiogenic effects. Ongoing work will determine the long-term effects of this combination with the goal of building in-situ flaps for tissue reconstruction.