BACKGROUND: Cryopreservation of oocyte has become most essential for the long-term conservation and widespread dispersion of animal genetic resources, but the efficiency of oocyte cryopreservation remains low. OBJECTIVE: The present study is to study the effect of hydroxyapatite (HA) nanoparticles on the survival rate of vitrified oocytes and the possible mechanism of cryopreserving oocytes with nanoparticles. MATERIALS AND METHODS: Porcine oocytes were vitrified in cryoprotectant (CPA) with biocompatible HA nanoparticles by Cryotop. The recrystallization of nano-CPA was observed with cryomicroscope. RESULTS: When 0.01%, 0.02%, 0.05% and 0.1% HA nanoparticles were added into vitrification solution, the survival rate of oocytes after in vitro maturation ranged from 25.9% to 35.4%, which is significantly higher than group without HA nanoparticles (14.7%). The microphotographs of oocytes in different solutions during freezing, thawing and melting showed that HA nanoparticles at a certain concentration can hinder the recrystallization of vitrification solution during rewarming. CONCLUSION: We speculate that preventing the recrystallization is the reason that nano-CPA can promote the survival rate of vitrified oocytes.
BACKGROUND: Cryopreservation of oocyte has become most essential for the long-term conservation and widespread dispersion of animal genetic resources, but the efficiency of oocyte cryopreservation remains low. OBJECTIVE: The present study is to study the effect of hydroxyapatite (HA) nanoparticles on the survival rate of vitrified oocytes and the possible mechanism of cryopreserving oocytes with nanoparticles. MATERIALS AND METHODS: Porcine oocytes were vitrified in cryoprotectant (CPA) with biocompatible HA nanoparticles by Cryotop. The recrystallization of nano-CPA was observed with cryomicroscope. RESULTS: When 0.01%, 0.02%, 0.05% and 0.1% HA nanoparticles were added into vitrification solution, the survival rate of oocytes after in vitro maturation ranged from 25.9% to 35.4%, which is significantly higher than group without HA nanoparticles (14.7%). The microphotographs of oocytes in different solutions during freezing, thawing and melting showed that HA nanoparticles at a certain concentration can hinder the recrystallization of vitrification solution during rewarming. CONCLUSION: We speculate that preventing the recrystallization is the reason that nano-CPA can promote the survival rate of vitrified oocytes.