Electrospun Tissue-Engineered Arterial Graft Thickness Affects Long-Term Composition and Mechanics

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Vascular Surgery

Background:

• Tissue-engineered vascular grafts often exhibit lower wall stress than native arteries due to stiff polymeric materials.
• This mechanical mismatch can create suboptimal conditions for infiltrating cells and tissue remodeling.
• Previous studies suggest increasing core:sheath ratio may enhance wall stress in engineered grafts.

Purpose of the Study:

• To design and evaluate murine arterial grafts with tailored mechanical environments.
• To investigate the impact of core:sheath ratio on cellular infiltration and vascular remodeling.
• To mitigate graft occlusion and rupture through modified electrospinning techniques.

Main Methods:

• Electrospinning of a compliant poly(glycerol sebacate) core and a stiffer poly(caprolactone) sheath.
• Design of two graft configurations differing in core thickness.
• Implantation of grafts in murine models to assess remodeling, mechanical properties, and patency.
• Analysis of collagen content, smooth muscle cell, and elastin deposition over 24 weeks.

Main Results:

• Modified electrospinning reduced core swelling and sheath residual stresses, improving graft patency.
• Thinner-core grafts exhibited higher collagen content and stiffness at 12 weeks post-implantation.
• Thicker-core grafts showed increased smooth muscle cell and elastin content by 24 weeks, becoming stiffer.
• Some grafts occluded due to thrombosis or ruptured, indicating areas for design improvement.

Conclusions:

• Adjusting the core:sheath ratio in electrospun arterial grafts can modulate local wall stress.
• Higher wall stress may promote more native-like tissue formation, including smooth muscle cells and elastin.
• Graft design influences early and late remodeling, suggesting potential for optimizing vascular tissue engineering strategies.