Date Published: April 17, 2017
Publisher: Public Library of Science
Author(s): Robert Novotny, Dasa Slizova, Jaroslav Hlubocky, Otakar Krs, Jaroslav Spatenka, Jan Burkert, Radovan Fiala, Petr Mitas, Pavel Mericka, Miroslav Spacek, Zuzana Hlubocka, Jaroslav Lindner, Alessandro Parolari.
The aim of our experimental work was to assess morphological changes of arterial wall that arise during different thawing protocols of a cryopreserved human aortic root allograft (CHARA) arterial wall.
The experiment was performed on CHARAs. Two thawing protocols were tested: 1, CHARAs were thawed at a room temperature at +23°C; 2, CHARAs were placed directly into a water bath at +37°C.
After fixation, all samples were washed in distilled water for 5 min, and dehydrated in a graded ethanol series (70, 85, 95, and 100%) for 5 min at each level. The tissue samples were then immersed in 100% hexamethyldisilazane for 10 minutes and air dried in an exhaust hood at room temperature. Processed samples were mounted on stainless steel stubs, coated with gold.
Thawing protocol 1: All 6 (100%) samples showed loss of the endothelium and damage to the subendothelial layers with randomly dispersed circular defects and micro-fractures without smooth muscle cells contractions in the tunica media.
All the samples thawed at the room temperature showed smaller structural damage to the CHARA arterial wall with no smooth muscle cell contraction in tunica media when compared to the samples thawed in a water bath.
Cryopreserved aortic root allografts (CHARA) have been used extensively in cardiac surgery for their advantages over bioprosthetic and mechanical valves, such as excellent hemodynamic function, very low thrombotic event rates, and mainly their resistance toward infections [1,2,3].
Histological analysis of the aortic root arterial wall was as follows:
Over the past four decades, cryopreservation of arterial allografts had shown inconsistent results in long term graft durability. In order to understand the changes that occur during cryopreservation and thawing of allografts, microscopic and immuno-histological techniques are used in order to determine structural and functional changes. One of the most important experimental works performed by M’ Bengue-Gaye A et al. on a rabbits carotid arteries clearly showed the effects of cryopreservation on allografts . It had been clearly demonstrated that allograft processing including cryopreservation and thawing are crucial in determining cryopreserved “muscular arteries” allografts durability and clinical performance [13,14].