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Open Access Highly Accessed Research article

The in vivo performance of small-caliber nanofibrous polyurethane vascular grafts

Zuo-jun Hu1*, Zi-lun Li1, Ling-yu Hu2, Wei He2, Rui-ming Liu1, Yuan-sen Qin1 and Shen-ming Wang1*

Author affiliations

1 Department of Vascular Surgery, The First Affiliated Hospital of Sun Yat-Sen University, No. 58 Zhongshan 2nd Road, Guangzhou, 510080, China

2 Guangzhou Women and Children’s Medical Center, Guangzhou, 510080, China

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Citation and License

BMC Cardiovascular Disorders 2012, 12:115  doi:10.1186/1471-2261-12-115

Published: 3 December 2012

Abstract

Background

In a previous in vitro study, we confirmed that small-caliber nanofibrous polyurethane (PU) vascular grafts have favorable mechanical properties and biocompatibility. In the present study, we examined the in vivo biocompatibility and stability of these grafts.

Methods

Forty-eight adult male beagle dogs were randomly divided into two groups receiving, respectively, polyurethane (PU) or polytetrafluoroethylene (PTFE) grafts (n = 24 animals / group). Each group was studied at 4, 8, 12, and 24 weeks after graft implantation. Blood flow was analyzed by color Doppler ultrasound and computed tomography angiography. Patency rates were judged by animal survival rates. Coverage with endothelial and smooth muscle cells was characterized by hematoxylin-eosin and immunohistological staining, and scanning electron microscopy (SEM).

Results

Patency rates were significantly higher in the PU group (p = 0.02 vs. PTFE group). During the first 8 weeks, endothelial cells gradually formed a continuous layer on the internal surface of PU grafts, whereas coverage of PTFE graft by endothelial cells was inhomogeneous. After 12 weeks, neointimal thickness remained constant in the PU group, while PTFE group showed neointimal hyperplasia. At 24 weeks, some anastomotic sites of PTFE grafts became stenotic (p = 0.013 vs. PU group). Immunohistological staining revealed a continuous coverage by endothelial cells and an orderly arrangement of smooth muscle cells on PU grafts. Further, SEM showed smooth internal surfaces in PU grafts without thrombus or obvious neointimal hyperplasia.

Conclusions

Small-caliber nanofibrous PU vascular grafts facilitate the endothelialization process, prevent excessive neointimal hyperplasia, and improve patency rates.

Keywords:
Nanofibers; Polyurethane; Small-caliber vascular grafts; Animal study