Rapid thawing increases the fragility of the cryopreserved arterial wall.
OBJECTIVE
To extend present knowledge of the biomechanical and structural changes which occur in the cryopreserved, rapidly thawed arterial wall.


METHODS
Minipig iliac arterial segments were cryopreserved at -196 degrees C in either minimum essential medium or Wisconsin solution. Fresh segments served as the control group. After 1 month, the specimens were rapidly thawed (37 degrees C) and processed for biomechanical, ultrastructural, morphological and immunohistochemical (MMP-1, MMP-2, MMP-3 and MMP-9) analysis. Visualisation of apoptotic cells was performed by TUNEL method. For the mechanical distension analysis, an in vitro circuit was designed.


RESULTS
The cryopreserved segments showed a 42% incidence of spontaneous fracture and the appearance of microfractures which affected the endoluminal third of the vessel. An accumulation of liquid in the subelastica was observed. An increased expression of wall-degradative enzymes (mainly MMP-2) was also observed following cryopreservation. No significant differences were detected in the proportional elasticity module or tensile strength of the specimen groups. No differences in mechanical distension were observed between groups after the vessel segments were subjected to the pulsatile circuit flow for 72 h. Cell damage was most intense in the specimens cryopreserved in Wisconsin solution.


CONCLUSIONS
Cryopreservation in both the solutions employed, followed by rapid thawing, induce changes in the permeability which increase the fragility of the cryopreserved arterial wall. Both increased expression of wall-degradative enzymes and accumulation of liquid may contribute to graft failure after implantation.
Buján
J
J
Department of Morphological Sciences and Surgery (Surgical Research Laboratory), Medical School, University of Alcalá, Madrid, Spain.
Pascual
G
G
García-Honduvilla
N
N
Gimeno
M J
MJ
Jurado
F
F
Carrera-San Martín
A
A
Bellón
J M
JM
D000241:Adenosine; D000493:Allopurinol; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001696:Biomechanical Phenomena; D002198:Capillary Fragility / Q000502:physiology*; D015925:Cryopreservation; D004730:Endothelium, Vascular / Q000473:pathology / Q000503:physiopathology; D005978:Glutathione; D007083:Iliac Artery / Q000473:pathology / Q000503:physiopathology; D020287:In Situ Nick-End Labeling; D007328:Insulin; D008666:Metalloendopeptidases / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D009131:Muscle, Smooth, Vascular / Q000473:pathology / Q000503:physiopathology*; D019188:Organ Preservation Solutions; D011887:Raffinose; D013552:Swine; D013556:Swine, Miniature
D007328:Insulin; D019188:Organ Preservation Solutions; C055206:University of Wisconsin-lactobionate solution; D000493:Allopurinol; D008666:Metalloendopeptidases; D005978:Glutathione; D000241:Adenosine; D011887:Raffinose