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Vitreous cryopreservation maintains the viscoelastic property of human vascular grafts
Author(s) -
Thakrar Raj R.,
Patel Vishal P.,
Hamilton George,
Fuller Barry J.,
Seifalian Alexander M.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.05-5304com
Subject(s) - pulsatile flow , cryopreservation , biomedical engineering , anatomy , viscoelasticity , materials science , pulse pressure , chemistry , blood pressure , medicine , composite material , biology , cardiology , embryo , radiology , microbiology and biotechnology
Assess the effects of cryopreservation (cryo) and vitrification (vitro) on the viscoelastic properties of blood vessels. Human external Iliac artery vessels were harvested from liver organ donors ( n =8). In each case the vessel was segmented into 3 equal parts, which were randomly placed in one of 3 categories: Fresh (stored in 4°C UW for 6 h), Cryo (Placed in 10% Dulbecco's modified Eagle medium (DMEM) and slowly frozen to −196°C), or Vitro (Placed in 40% DMEM and rapidly cooled to −196°C). A pulsatile flow circuit was used to perfuse arterial segments at physiological pulse pressure and flow. Intraluminal pressure was measured using a Millar Mikro‐tip catheter transducer, and vessel wall motion was determined with duplex ultrasonography coupled with a novel echo‐locked vessel wall tracking system. Diametrical compliance (DC), Petersons elastic modulus (Ep), and stiffness index (β) were then calculated for each of the three groups over 3 mean pressure ranging from 40 to 80 mmHg. The change in the viscous component of arterial wall (lag phase angle, θ) was calculated from hysteresis plots. No significant changes were observed in the elastic properties of fresh and vitrified vessels ( P >0.05 for each of DC, Ep, and β). Similarly, variation in the wall viscosity between fresh and vitrified vessels appeared to be nonsignificant (θ = 12.60±4.04 vs. 17.60±1.14, respectively). In contrast, statistical analysis of results obtained for cryopreserved vessels to the fresh vessels showed significant reduction in elastic parameter values. There was also a significant increase in the phase angle θ of the cryopreserved vessels (θ = 24.30±6.32; P < 0.001) compared with fresh vessel. Results suggest that vitrification maintains both elastic and viscous components of the mechanical properties of vascular grafts, which is positively correlated with their functional patency. In contrast, damage caused during cryopreservation significantly affects the overall tensile strength and elasticity of the vessel (i.e., Ep and β), the dynamic properties (DC), and appears to significantly affect the viscous component of the vessel wall (θ), which is likely reduce the patency of the graft for transplantation purposes.—Thakrar, R. R., Patel, V. P., Hamilton, G., Fuller, B. J., Seifalian, A. M. Vitreous cryopreservation maintains the viscoelastic property of human vascular grafts. FASEB J. 20, 874–881 (2006)