(154d) Short and Long-Term Vascular Network Patterning Using Hybrid Microsurgery and Granular Hydrogel Scaffolds

In reconstructive surgery, hydrogels are often used for tissue repair and regeneration. However, conventional nanoporous bulk hydrogels have limitations, particularly slow and random vascularization, often resulting in impaired tissue healing. To overcome these challenges, this study presents a novel strategy that combines microsurgical techniques with granular hydrogel scaffolds (GHS) for enhanced neovascularization. Different sizes of gelatin methacryloyl (GelMA) droplets were transformed into microscale hydrogel particles (microgels) by physical crosslinking, followed by chemical assembly to yield GHS with varying pore sizes. Micropuncture (MP) was performed in a rat hindlimb model via perforating blood vessels, followed by implanting the GHS on the blood vessels. Immunostaining and angiography confirmed accelerated and guided microvascular network formation using MP/GHS compared with the MP/bulk hydrogel counterpart. Furthermore, we investigated the extent of vascularization and macrophage accumulation after 7 days and compared them with a later time point (28 days). Our results showed increased vascular loops, branches, and density 28-days after surgery. Additionally, tube length and intercapillary distance remain relatively unchanged after 4 weeks of implantation. Overall, our findings suggest that this hybrid approach may hold promise for accelerating and guiding microvascular network formation, which may open new avenues for reconstructive surgery and regenerative engineering.