Electrospun polydioxanone–elastin blends: potential for bioresorbable vascular grafts

INSTITUTE OF PHYSICS PUBLISHING

BIOMEDICAL MATERIALS

doi:10.1088/1748-6041/1/2/004

Biomed. Mater. 1 (2006) 72–80

Electrospun polydioxanone–elastin blends: potential for bioresorbable vascular grafts ∗ S A Sell1, M J McClure1, C P Barnes1, D C Knapp1, B H Walpoth2, D G Simpson1 and G L Bowlin1 1 2

Virginia Commonwealth University, Richmond, VA 23298, USA University Hospital, 1211 Geneva 14, Switzerland

Received 30 March 2006 Accepted for publication 11 April 2006 Published 4 May 2006 Online at stacks.iop.org/BMM/1/72 Abstract An electrospun cardiovascular graft composed of polydioxanone (PDO) and elastin has been designed and fabricated with mechanical properties to more closely match those of native arterial tissue, while remaining conducive to tissue regeneration. PDO was chosen to provide mechanical integrity to the prosthetic, while elastin provides elasticity and bioactivity (to promote regeneration in vitro/in situ). It is the elastic nature of elastin that dominates the low-strain mechanical response of the vessel to blood flow and prevents pulsatile energy from being dissipated as heat. Uniaxial tensile and suture retention tests were performed on the electrospun grafts to demonstrate the similarities of the mechanical properties between the grafts and native vessel. Dynamic compliance measurements produced values that ranged from 1.2 to 5.6%/100 mmHg for a set of three different mean arterial pressures. Results showed the 50:50 ratio to closely mimic the compliance of native femoral artery, while grafts that contained less elastin exceeded the suture retention strength of native vessel. Preliminary cell culture studies showed the elastin-containing grafts to be bioactive as cells migrated through their full thickness within 7 days, but failed to migrate into pure PDO scaffolds. Electrospinning of the PDO and elastin-blended composite into a conduit for use as a small diameter vascular graft has extreme potential and warrants further investigation as it thus far compares favorably to native vessel. (Some figures in this article are in colour only in the electronic version)

1. Introduction Cardiovascular disease, specifically coronary artery disease resulting from arteriosclerosis, remains one of the leading causes of death in the United States. Arteriosclerosis is a vascular disease that is characterized by thickening of the arterial wall and the subsequent decrease in the arterial lumen leading to eventual decrease or loss of circulation distal to the disease site. Once blood flow is compromised, vascular ∗

Disclosure. Several authors have United States and International patents pending concerning technology presented in this article, and this technology has been licensed to NanoMatrix, Inc., in which several authors have a financial interest.

1748-6041/06/020072+09$30.00

bypass is an option to restore blood flow to tissues distal to the restriction or blockage. In 2000 there were an estimated 519 000 coronary bypass surgeries performed [1], which typically involve the replacement of a coronary artery with an autologous saphenous vein or internal mammary artery. While these autologous alternatives perform at an acceptable patency level, they are not always a viable option as the vessels may themselves be diseased if the patient suffers from peripheral vascular disease, which in its own right affects upward of 12 million Americans with significant associated mortality, or a previous bypass operation may have already required their use [2]. Synthetic vessels made of expanded polytetrafluoroethylene (e-PTFE) and woven or R ) knitted polyethylene terephthalate (PET) fibers (Dacron

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Electrospun polydioxanone–elastin blends: potential for bioresorbable vascular grafts

have been utilized as bypass grafts for peripheral arteries for quite some time. These graft materials function adequately as medium (6–10 mm internal diameter, ID) and large (>10 mm ID) prosthetics in areas where there is high flow and low resistance. The functionality of these synthetic polymers as small diameter vessels (