129. Micropuncture Vascularization of Intraoperative Bioprinted Scaffolds
Year: 2023
Type: article
Abstract: PURPOSE: Tissue loss is a major cause of worldwide morbidity and plastic surgeons are tasked with its correction. Reconstructive approaches often rely on autologous tissue transfer, but these methods are suboptimal for a multitude of reasons and are rooted in antiquated principles. Intraoperative tissue reconstruction via bioprinting represents the next generation of reconstructive surgery. Although promising, translation and scalability have been limited by poor vascularization from the recipient. Recently, we described a microsurgical approach which rapidly vascularizes an adjacently placed scaffold. In micropuncture (MP), the recipient blood vessel wall is precisely disrupted to provide an immediate route for cellular extravasation. We hypothesized that MP integration with intraoperative bioprinting (IOB) would improve construct vascularization. METHODS: Using a rat hindlimb model, microsurgery was integrated with bioprinting. The femoral vessels underwent transmural 60-um diameter micropunctures at defined intervals (n=5). Controls (n=5) did not receive any MPs. Immediately after, an extrusion bioprinter was brought into the operative field and deposited a collagen-based scaffold directly over the vasculature. Following scaffold solidification, the skin was closed. At Day 10 animals underwent laser doppler and in situ fluorescence angiography. Explants were prepared for both whole mount and thin section histology. Endothelial (CD31) and nucleated (DAPI) cell infiltration were assessed with immunofluorescence and quantified with ImageJ. Artificial intelligence (AI; MetaVi Labs, Austin, TX) analyzed scaffolds for various vessel metrics including mean density, total tube length, and diameter along with branch and loop counts. Statistical significance was defined as p<0.05. RESULTS: At Day 10, there was a 3-fold increase in MP scaffold perfusion when compared to non-MP controls (6.72 mL/min versus 1.99mL/min) although this did not reach statistical significance (p=0.06). Increased endothelial cell infiltration within MP scaffolds was noted by mean CD31 staining area (3.3% versus 1.76% per HPF; p<0.01). This was paralleled by augmented nucleated cell counts (8.3% versus 5.8% per HPF; p<0.01). Whole mount angiography demonstrated a 2-fold increase in vascular density of MP bioprinted scaffolds (20.4% versus 9.86%; p<0.01). Capillary network expansion was predominately attributed to increased branch numbers within MP scaffolds (120 versus 45 per HPF; p<0.01) which also resulted in more loop formations (43 versus 12 per HPF; p<0.01). Total tube length (28,843 versus 13,661 um per HPF; p<0.01) and average vessel diameter (59.35 versus 48.81 um per HPF; p<0.01) were also increased with MP. CONCLUSION: Here we demonstrate the integration of microsurgery and intraoperative bioprinting as a platform approach for engineered tissue vascularization. Like with manually implanted scaffolds, MP also appears suitable with collagen-based bioinks and creates a similar pro-angiogenic microenvironment. Ongoing work will determine feasibility of cellularized constructs with the long-term goal of building a flap for in-situ tissue reconstruction.
Institution: Pennsylvania State University
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,195
OpenAlex ID: W4384948571