Tracheal replacement remains an important unmet need for patients with extensive lesions. Tracheal allografts treated by cryopreservation and lyophilization have been used as experimental methods for replacing long segments of the trachea. We compare the effect of lyophilization and cryopreservation on the canine tracheal cartilage by microscopic evaluation of necrotic cell death. Canine tracheal segments were rinsed and randomly divided into a control group (G1) and two biopreservation groups: lyophilization (G2) [−70–55°C/10 mmBar] and cryopreservation (G3) [RPMI-1640 + 10%DMSO + 10%SBF, −70°C/−196°C]. After tracheal segments were rehydrated (G2) or thawed (G3), the central ring was obtained from each tracheal segment and processed for histological evaluation with hematoxylin and eosin and for caspase-3 expression by immunohistochemistry. Compared with the control group, chondrocytes without apparent abnormalities, nucleus with karyorrhexis, and caspase-3 expression decreased significantly with the effect of lyophilization and cryopreservation (p < 0.001, ANOVA + Tukey, chi-square, Kruskal-Wallis), while a significant decrease in pyknotic nuclei was observed only with the effect of the lyophilization as well as an increase in the nucleus with karyolysis and empty lacunae (p < 0.001, ANOVA + Tukey). The mean percentages of normal chondrocytes and empty lacunae were significantly affected by lyophilization compared with cryopreservation (p < 0.01, ANOVA + Tukey). Our results strongly suggest that lyophilization has a deleterious impact on the tracheal cartilage.
Part of the book: Cryopreservation in Eukaryotes