Long‐term evaluation of vascular grafts with circumferentially aligned microfibers in a rat abdominal aorta replacement model

Abstract

Long-term results of implants in small animal models can be used to optimize the design of grafts to further promote tissue regeneration. In previous study, we fabricated a poly(ɛ-caprolactone) (PCL) bi-layered vascular graft consisting of an internal layer with circumferentially aligned microfibers and an external layer with random nanofibers. The circumferentially oriented vascular smooth muscle cells (VSMCs) were successfully regenerated after the grafts were implanted in rat abdominal aorta for 3 months. Here we investigated the long-term (18 months) performance of the bi-layered grafts in the same model. All the grafts were patent. No thrombosis, aneurysm, or stenosis occurred. The endothelium maintained complete. However, most of circumferentially oriented VSMCs migrated to luminal surface of the grafts to form a neointima with uniform thickness. Accordingly, extracellular matrix including collagen, elastin, and glycosaminoglycan displayed high density in neointima layer while with low density in the grafts wall because of the incomplete degradation of PCL. A small amounts of calcification occurred in the grafts. The contraction and relaxation function of regenerated neoartery almost disappeared. These data indicated that based on the structure design, many other factors of grafts should be considered to achieve the regenerated neoartery similar to the native vessels after long-term implantation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2596-2604, 2018.

Mechanically reinforced biotubes for arterial replacement and arteriovenous grafting inspired by architectural engineering

“…The complete in vivo degradation of PCL takes approximately 18 months. Slow degradation rates of polymers are considered beneficial in the avoidance of rapid mechanical loss during early remodeling stages of tissue regeneration ( 34 , 45 ). At 7 months after VI of hMPB (hMPB-V7m), the PCL fibers exhibited signs of fragmentation ( Fig.…”

“…S23). Previously, it was shown that ECM deposition effectively compensated for loss of mechanical strength due to polymer degradation, and this helped avoid graft dilatation or rupture ( 45 , 46 ). In support of this, we found no signs of dilatation or rupture in hMPB-V7m ( Fig.…”

Tissue‐Engineered Vascular Grafts: Emerging Trends and Technologies

“…However, their lost physiological function and calcification concluded that geometric resemblance alone is not as effective as was initially believed. [ 92 ] In a concerted effort, immobilization of heparin on topographically aligned luminal surface resulted in superior neovessel remodeling, long‐term patency, and rapid in situ endothelialization in rabbit carotid artery after 3 months. [ 93 ] TEVGs with circumferentially oriented micro‐channels guided cell orientation and assisted rapid endothelialization via recruitment and M2 polarization of macrophages in rat aortic implantation model.…”

Nanoparticle-Assisted Diagnosis and Treatment for Abdominal Aortic Aneurysm

“…However, the contraction and relaxation function of regenerated neoartery almost disappeared. Other factors of grafts should be considered to achieve the regenerated artery similar to the native vessels after long-term implantation, but this is still a potential orientation in AAA graft ( 94 ). What is more, combining electrospinning and 3D printing to create patient-specific nanofiber tissue-engineered vascular grafts (TEVGs) is a feasible technology as a future clinical option.…”