Cryopreserved human aortic root allografts arterial wall: Structural changes occurring during thawing

Abstract

BackgroundThe 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.MethodsThe 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.Microscopic samples preparationAfter 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.ResultsThawing 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.Thawing protocol 2: All 6 (100%) samples showed loss of endothelium from the luminal surface, longitudinal corrugations in the direction of blood flow caused by smooth muscle cells contractions in the tunica media with frequent fractures in the subendothelial layerConclusionAll 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.

Cell Viability Assessment Using Fluorescence Vital Dyes and Confocal Microscopy in Evaluating Freezing and Thawing Protocols Used in Cryopreservation of Allogeneic Venous Grafts

“…The research group of David Pegg already proved in the 90 s that micro-fractures of the arterial wall caused by devitrification may occur during rapid thawing [ 22 , 23 ]. Microfractures in human arterial grafts were also described by Novotný [ 24 ]. In the clinical situation, such an event can cause early graft rupture of thawed arterial grafts [ 16 , 17 , 25 , 26 ].…”

The Effect of Different Thawing Rates on Cryopreserved Human Iliac Arteries Allograft’s Structural Damage and Mechanical Properties

“…Experimental models dealing with CA functional properties and structural damage caused by cryopreservation have been published scarcely [ 11 ]. Nevertheless, research papers dealing with similar experimental models on human CA are even rarer [ 12 – 14 ]. However, none of these papers had tried to correlate structural changes of human CA caused by thawing and their direct effect on CA mechanical properties.…”

Layered patterns in nature, medicine, and materials: quantifying anisotropic structures and cyclicity

“…Macro-, micro-, and nanostructures play a vital role in understanding pattern formation and relationships between processes and structures (Aizenberg & Fratzl, 2009). Central problems in studying layered objects—particularly in medicine (Novotny et al, 2017), materials science (Deville, 2018), and biomimetic research (Meyers, Hodge & Roeder, 2008; Gilbert et al, 2017)—are quantitatively describing the relationship between structure and properties, tracking structural changes over a period of time, and revealing structural anomalies. Experiments with various categories of layered systems justify the possibility of using EM = {BF, G ( N ), T M , N } to help to solve these problems.…”

“…The human aorta has a layered (i.e., lamellar) structure that typifies the elastic lamina found in human and animal blood vessels. The study of aortic microstructure and age-related changes is an urgent area of medical research (Novotny et al, 2017; Selçuk et al, 2015).…”