Étude des caractéristiques biomécaniques sur la préservation des nerfs

Abstract

Different studies have described the biomechanics of nerves. An important dispersion of outcomes can be observed and can be explained by the biological nature of tissues, the different experimental protocols like different conditions of testing and different preservation solutions that modify they biomechanical behavior. Nevertheless, the influence of preservation solution on biomechanics has not been well characterized. It is capital to quantify the amount of solution absorbed by the nerve during the preservation process before the test in order to understand the different biomechanical behaviors seen on the literature. The next experiment is focused on the characterization of the influence from preservation solution on the rat sciatic nerves biomechanics. Male 6 weeks old Wistar rat sciatic nerves were harvested ex vivo rats 300 g weight. The rats were donated after being used for microsurgery training. During the study, the nerves were preserved on 4 different preservation solutions: PBS, mineral oil, glucose 30% and NaCl0.9%. Nine rat sciatic nerves were used to test the influence of the preservation solutions chosen. The protocol used in the literature works with a unidirectional tensile test. The elastic modulus and stress strain curves were obtained with this specific software. The displacement was measured at a specific time t and the initial length lo as the initial length between the clamps. The sciatic nerve harvesting and the preservation solution have influenced different characteristics. The mineral oil and NaCl do not allow an optimal preservation of nerves. After few days of preservation, the nerve was physically damaged, deformed and even in a putrefaction state judging by the odor of the containers. The preservation modes have a remarkable influence on the physical integrity of the nerve. Additionally, an important absorption capacity of the nerve has been demonstrated. The obtained results showed a twofold increase of weight during few days (mass augmentation more than a 100%). The results have shown that PBS changes the biomechanical behavior of nerves by diminishing the elastic modulus and a by increasing the maximal strain when the solution diffuse into the material. These behavior variations are necessarily linked to the nature of nerves, because the observed variations were confirmed on the nerve microstructure. The influence of preservation solutions on biomechanical properties has been characterized on the rat sciatic nerves. PBS could be a good preservation solution given the dispersion of values during the test, a deep analysis was performed with PBS preserved nerves.