Multiscale Mechanical Study of Proanthocyanidins for Recovering Residual Stress in Decellularized Blood Vessels

Decellularized artificial blood vessels prepared using physical and chemical methods often exhibit limitations, including poor mechanical performance, susceptibility to inflammation and calcification, and reduced patency. Cross-linking techniques can enhance the stiffness, as well as anti-inflammatory and anti-calcification properties of decellularized vessels. However, conventional cross-linking methods fail to effectively alleviate residual stress post-decellularization, which significantly impacts the patency and vascular remodeling following the implantation of artificial vessels. This study enhances vascular residual stress through varied conditions of proanthocyanidin (PC) cross-linking on decellularized vessels. Microstructural analysis and mechanical investigations across various scales of fresh, decellularized, and residual stress-recovered vessels are performed using atomic force microscopy (AFM), scanning electron microscopy (SEM), and uniaxial tensile testing. Results demonstrate substantial alterations in the morphology of elastic and collagen fibers post-decellularization, which remarkably resemble fresh vessels following residual stress recovery. Furthermore, both the micro- and macro-mechanical characteristics of vessels post-residual stress recovery, including Young's modulus, viscoelasticity, and adhesion, closely resemble those of fresh vessels. Finite element modeling (FEM) confirms the distribution of residual stress and its role in enhancing vascular mechanical integrity. This experimental investigation provides a theoretical foundation at both micro and macroscopic levels for the development of biomimetic blood vessels.