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Enhanced Scaffold Vascularization via Micropuncture and Aptamer-mediated VEGF Delivery
Ji Ho Park
*1, Connie Wen
3, Neekita Jikaria
1, Mary Landmesser
2, Jazzmyn Dawes
2, Yong Wang
3, Dino Ravnic
11Surgery, Penn State Milton S. Hershey Medical Center, Hummelstown, PA; 2Pennsylvania State University College of Medicine, Hershey, PA; 3Biomedical Engineering, Pennsylvania State University, University Park, PA
Background: Hydrogel scaffolds (HS) are integral to both reconstructive surgery and tissue engineering. Their success depends on rapid and robust vascularization. Previously, we described a pro-angiogenic surgical approach, micropuncture (MP), which primes recipient sites for biomaterial vascularization. Scaffold modifications like VEGF incorporation can provide a synergizing effect but are limited by ineffective release kinetics. Aptamers"”short, single-stranded nucleic acids"”offer means for controlled protein sequestration and release. We hypothesize that MP with aptamer-functionalized HS (AHS) for VEGF delivery will augment scaffold vascularization.
Methods: The AHS were synthesized by free radical polymerization, loaded with VEGF, then tested
in vitro for release kinetics.
In vivo, 60 μm diameter MPs were made at 1-mm intervals in rat femoral vessels, followed by adjacent scaffold implantation (n=6 per group). Scaffold groups were AHS + 200 ng VEGF and AHS + 400 ng VEGF with HS + 400 ng VEGF (no aptamer) serving as a baseline control. On Day 14,
in situ whole-mount angiography was performed and scaffolds were explanted for vascular quantification (ImageJ, NIH). A Kruskal-Wallis test with Dunn's post-hoc analysis was performed; statistical significance was defined as p<0.05.
Results: In vitro analysis demonstrated that the incorporation of aptamers in HS reduced the burst release of VEGF by half and allowed for sustained release for over two weeks.
In vivo studies demonstrated that AHS-mediated VEGF delivery increased scaffold vascularization compared to the no aptamer control. Furthermore, there was a dose-dependent increase in scaffold vascular density between the AHS groups (
Figures 1 A, B).
Conclusion: Combining MP with aptamer-mediated VEGF delivery synergistically enhances scaffold vascularization. This study underscores the power of integrating surgical and materials-based strategies to optimize scaffold vascularization. Future studies will identify the optimal therapeutic balance between angiogenic potency and toxicity.
Figure 1. Increased scaffold vascularization from recipient vessels following MP and aptamer-mediated VEGF delivery. (
A)
Whole mount angiography (scale bar = 400 μm). (
B) Vascular density as measured by % area staining (ImageJ, NIH). The different color data points correspond to each animal. ****: p <0.0001; ns: Not significant.
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