title: Magnetic forces enable rapid endothelialization of synthetic vascular grafts.
abstract: BACKGROUND
  Synthetic vascular grafts cannot be used in small vessels because of graft failure caused by thrombosis and neointima formation. Rapid endothelialization may overcome this limitation. We hypothesized that a magnetic graft would be able to capture and retain endothelial cells labeled with paramagnetic particles.
  
  
  RESULTS
  Porcine blood derived endothelial cells were allowed to endocytose superparamagnetic iron oxide microspheres. Cell survival was assessed by trypan blue exclusion and demonstrated a dose-dependent cell survival of 75% to 95%. A flexible magnetic sheet was annealed to the external surface of a knitted Dacron graft. Labeled cells (10(6)/mL) were placed within the graft for 5 minutes. Confocal and electron microscopy confirmed uniform cell capture at the magnetized surface. The effect of shear forces on the adherent cells was evaluated in a flow chamber. The cells remained attached at rates up to 300 mL/min, with cell loss commencing at 400 mL/min. Prototype magnetic grafts were implanted in porcine carotid arteries. Labeled cells were placed within the graft for 10 minutes at the time of implantation. The grafts were evaluated after one day and uniform cell coverage was noted on the magnetized surface. In comparison, relatively few labeled cells were seen attached to a nonmagnetized surface.
  
  
  CONCLUSIONS
  Magnetic forces can be used to rapidly cover a vascular graft with paramagnetically labeled cells. This biophysical interaction is sufficient to retain cells in the presence of blood flow. Applications of this technique may include rapid endothelialization of synthetic vascular grafts and dialysis fistulas.
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, Minnesota 55905, USA.
authors.forename: Sorin V
authors.initials: SV
authors.lastname: Pislaru
authors.forename: Adriana
authors.initials: A
authors.lastname: Harbuzariu
authors.forename: Gautam
authors.initials: G
authors.lastname: Agarwal
authors.forename: Tyra
authors.initials: T
authors.lastname: Witt
authors.forename: Rajiv
authors.initials: R
authors.lastname: Gulati
authors.forename: Nicole P
authors.initials: NP
authors.lastname: Sandhu
authors.forename: Cheryl
authors.initials: C
authors.lastname: Mueske
authors.forename: Manju
authors.initials: M
authors.lastname: Kalra
authors.forename: Robert D
authors.initials: RD
authors.lastname: Simari
authors.forename: Gurpreet S
authors.initials: GS
authors.lastname: Sandhu
mesh_terms: D000818:Animals; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation; D002448:Cell Adhesion; D002470:Cell Survival; D002478:Cells, Cultured / Q000166:cytology; D004705:Endocytosis; D042783:Endothelial Cells / Q000166:cytology*; D004730:Endothelium, Vascular / Q000166:cytology; D004867:Equipment Design; D005290:Ferric Compounds; D006083:Graft Occlusion, Vascular / Q000517:prevention & control; D020007:Implants, Experimental; D008280:Magnetics; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008863:Microspheres; D011093:Polyethylene Terephthalates; D011673:Pulsatile Flow; D034421:Sus scrofa
chemical_list: D005290:Ferric Compounds; D011093:Polyethylene Terephthalates; C000499:ferric oxide