title: The in vivo performance of small-caliber nanofibrous polyurethane vascular grafts.
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.
authors.affiliation: Department of Vascular Surgery, The First Affiliated Hospital of Sun Yat-Sen University, No, 58 Zhongshan 2nd Road, Guangzhou, 510080, China. zuojunhu@hotmail.com
authors.forename: Zuo-jun
authors.initials: ZJ
authors.lastname: Hu
authors.forename: Zi-lun
authors.initials: ZL
authors.lastname: Li
authors.forename: Ling-yu
authors.initials: LY
authors.lastname: Hu
authors.forename: Wei
authors.initials: W
authors.lastname: He
authors.forename: Rui-ming
authors.initials: RM
authors.lastname: Liu
authors.forename: Yuan-sen
authors.initials: YS
authors.lastname: Qin
authors.forename: Shen-ming
authors.initials: SM
authors.lastname: Wang
mesh_terms: D000818:Animals; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation; D004285:Dogs; D004730:Endothelium, Vascular / Q000502:physiology; D008297:Male; D057139:Nanofibers; D058426:Neointima / Q000517:prevention & control; D011138:Polytetrafluoroethylene; D011140:Polyurethanes; D014654:Vascular Patency
chemical_list: D011140:Polyurethanes; D011138:Polytetrafluoroethylene