Balancing Scaffold Degradation and Neo-Tissue Formation in In Situ Tissue Engineered Vascular Grafts

Area of Science:

• Biomaterials Science
• Cardiovascular Engineering
• Tissue Engineering

Background:

• Cardiovascular tissue engineering (TE) requires scaffolds that degrade at a rate matching neo-tissue formation.
• Balancing scaffold degradation and tissue regeneration is crucial for successful TE applications.

Purpose of the Study:

• To evaluate the degradation rates and neo-tissue formation of three electrospun bisurea-based biodegradable scaffolds with varying soft-block backbone compositions.
• To assess the in vivo performance of these scaffolds as interposition grafts in a rat abdominal aorta model.

Main Methods:

• Implantation of electrospun scaffolds (fully carbonate-based vs. ester-containing) into rat abdominal aortas.
• Evaluation at multiple time points (1-40 weeks) assessing function, tissue formation, strength, degradation, and mineralization.
• Magnetic resonance imaging (MRI) to compare vessel wall contrast enhancement.

Main Results:

• Fully carbonate scaffolds exhibited minimal degradation over 40 weeks, while ester-containing scaffolds degraded within 6-12 weeks.
• Faster degrading scaffolds showed local dilatation; all scaffolds displayed some mineralization.
• Histology revealed similar, non-native neo-tissue formation post-degradation. Carbonate scaffolds showed delayed neo-tissue formation.
• MRI indicated significant differences in contrast enhancement between minimally and fully degraded scaffolds.

Conclusions:

• Scaffold degradation rate critically influences cardiovascular TE outcomes, with implications for dilatation and neo-tissue formation.
• A balance between degradation and tissue integration is essential for effective vascular graft TE.
• The choice of backbone composition (carbonate vs. ester) significantly impacts scaffold degradation kinetics and in vivo performance.