BACKGROUND: To recover good blood supply is critical to the cryopreservation and replantation of composite tissues, and different cryopreservation techniques have different effects on vascular activity.
OBJECTIVE: To compare the activity of vascular endothelial cells of composite tissue following rapid-freezing and slow-freezing methods.
METHODS: Forty New Zealand white rabbits were randomly divided into control group, cryopreservation for 12 hours group, 3 days group, 7 days group, with 10 in each group. Control group was without any treatment. In the experimental groups, New Zealand white rabbit hind limbs were divided into two subgroups, receiving rapid freezing and slow freezing. The hind limbs in the rapid freezing group were put into liquid nitrogen for 12 hours, 3 days, and 7 days. In the slow-freezing group, the freezing procedure was carried out at 4 ℃, -20 ℃ and -80℃, successively, using programmed frozen. All the groups required cryopreservation for 12 hours, 3 days, and 7 days, and then rapid rewarming. After thawing, pathological changes in the vascular endothelium were examined by optical microscope and immunohistochemical staining.
RESULTS AND CONCLUSION: The scores on the morphology of vascular endothelial tissues were higher in the control group than the two freezing groups following cryopreservation for 12 hours, 3 days, and 7 days (P < 0.05). The scores on vascular endothelial growth factors were higher in the slow-freezing group than the rapid-freezing group (P < 0.05). These findings indicate that slow-freezing is superior to rapid-freezing to preserve the biological activity of vascular endothelial cells of composite tissue.