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Next-generation Porous Hydrogel Scaffolds With Tunable Stiffness Modulate In Situ Microvascular Growth And Maturation
Mohammad Hossein Asgardoon, MD, MPH1, Saman Zavari, MS
2, Yuanhui Xiang, PhD
2, Amir Sheikhi, phD
2, Dino J. Ravnic, DO, MPH
1.
1Irvin S. Zubar Plastic Surgery Research Laboratory, Division of Plastic Surgery, Department of Surgery, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, USA,
2Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA.
PURPOSE:In situ scaffold formation is an emerging strategy for intraoperative tissue reconstruction. The easy dispensability of hydrogels allows for precise wound contouring; however, their success depends on rapid vascular integration. While stiffness regulates microvascular growth in bulk hydrogels, its effect in porous systems remains unclear. We hypothesized that more compliant porous hydrogels augment microvascular growth and maturation.
METHODS:Gelatin methacryloyl (GelMA) particles with storage moduli of 1, 5, or 21 kPa were UV-cured in situ to form soft, medium, and hard scaffolds (15×15×3 mm) subcutaneously on the dorsum of rats (n=9/group). On postoperative day 7 (POD7), blood perfusion and surface temperature were measured
in situ using laser Doppler and thermal imaging. Following intravenous injection of FITC-dextran and Evans Blue, scaffolds were imaged by confocal microscopy. Microvascular parameters were quantified using FastTrack AI, and a permeability index was calculated from Evans Blue extravasation normalized to FITC-dextran area. Data were analyzed by one-way ANOVA (p<0.05).
RESULTS:
Soft scaffolds showed the highest perfusion, surface temperature, vascular density, branching, and loop counts, which declined progressively with increasing stiffness. Vessel diameter remained similar across groups. Evans Blue area and permeability index were greatest in soft scaffolds (Table1).
CONCLUSION:GelMA particle stiffness regulates microvascular growth and permeability. Softer scaffolds promote greater vascularization yet incomplete maturation at POD7. GelMA particles hold promise as tunable materials for next-generation reconstructive surgery.
Table 1. Effect of GelMA particle stiffness on microvascular growth and maturation. * p<0.05| Parameter | Soft (mean ± SEM) | Medium (mean ± SEM) | Hard (mean ± SEM) |
| Scaffold Doppler intensity (AU) | 354.10 ± 68.26* | 257.40 ± 59.48 | 192.00 ± 41.00 |
| Scaffold temperature (°C) | 29.76 ± 0.48* | 27.30 ± 0.45* | 25.67 ± 0.47 |
| Vascular density (%) | 19.78 ± 1.22* | 15.24 ± 0.49* | 12.20 ± 0.69 |
| Number of branches (n) | 52.40 ± 6.63* | 37.27 ± 6.67 | 26.07 ± 5.48 |
| Number of loops (n) | 23.40 ± 2.73* | 14.60 ± 1.73 | 11.87 ± 2.04 |
| Average vessel diameter (µm) | 17.98 ± 0.74 | 18.45 ± 1.05 | 18.18 ± 1.24 |
| Evans Blue area (%) | 17.04 ± 1.02* | 10.23 ± 0.70* | 6.74 ± 0.45 |
| Permeability index | 0.86 ± 0.01* | 0.67 ± 0.04* | 0.55 ± 0.02 |
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