Impact of Tissue Freezing on the Functional and Biomechanical Characteristics of Porcine Aortic Roots

Freeze-preservation of porcine aortic tissue is often necessary for experimental planning and standardization, but the impact of freezing on aortic root properties has not been systematically investigated. This study evaluated the effects of freezing and thawing on the biomechanical, fluid dynamic, and ultrasonographic characteristics of porcine aortic roots.

A total of 32 porcine hearts were obtained from a local abattoir. Specimens were randomized to a fresh group (immediate testing) or a thawed group (storage at - 20 °C for 30 days followed by thawing in saline). Uniaxial tensile testing was performed on samples from the sinotubular junction (STJ) and non-coronary cusp (NCC) (n = 10 per group). Functional testing was conducted in a pulsatile flow loop (n = 6 per group), with mean aortic pressure gradient, forward and retrograde flow measured and the regurgitant fraction calculated. Ultrasonography was used to assess annular diameters and coaptation lengths.

Tensile testing revealed no statistically significant differences in E-module, maximum stress, maximum load, or stiffness between fresh and thawed specimens at either the STJ or NCC. Mean aortic gradient, retrograde flow and regurgitant fraction did not differ. Ultrasonography showed no statistically significant changes in annular geometry or leaflet coaptation length after freezing and thawing.

Freezing and thawing did not result in measurable differences in the biomechanical, fluid dynamic, or geometrical properties of porcine aortic roots under the tested protocol and within the sensitivity of our measurements. These findings support the use of thawed porcine aortic roots in experimental cardiovascular research.