| Co-Investigator(Kenkyū-buntansha) |
SUGIMOTO Miki Kyoto University, Faculty of Agriculture, Assistant, 大学院・農学研究科, 助手 (20243074)
EDASHIGE Keisuke Kochi University, Faculty of Agriculture, Associate professor, 農学部, 助教授 (30175228)
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| Research Abstract |
The present study aimed to examine the efficacy of ultrarapid vitrification and to develop new strategies for the cryopreservation of mammalian oocytes and embryos, based on the understanding of fundamental cryobiology.
Ultrarapid vitrification using the cryoloop was effective for human blastocysts, in which conventional vitrification does not yield consistent results. For mouse oocytes, the post-warming survival after vitrification using cryoloops was not different from that after vitrification using conventional straws. For rat embryos, in which the efficacy of vitrification has not reached a level for practical use, conventional straw vitrification using EFS solution was quite effective, on the condition that embryos at suitable stages of development are used. As a tool to identify the mechanism of injury, we specified morphological characteristics of embryos that is typical to specific types of injuries, such as intracellular ice formation and cryoprotectant toxicity. As a potential
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strategy for cryopreservation, we tried to increase the permeability of the cell membrane artificially. We injected cRNA of a certain type of aquaporins, a water channel that can transport not only water but also cryoprotectants, into mouse oocytes. In oocytes injected with cRNA of aquaporin 3, both water permeability and glycerol permeability increased significantly. These oocytes survived after vitrification in a solution based on glycerol, which scarcely permeates into intact oocytes, whereas none of oocytes injected with water survived after vitrification in the solution. The oocytes in which the plasma membrane was temporarily 'altered' retained the ability to be fertilized and to develop to term.
The results obtained in this study would be valuable for the cryopreservation of embryos and oocytes in domestic animals, laboratory animals and humans. In addition, a new strategy found in this study would have potential advantage for the cryopreservation of various genetic resources that need to be preserved. Less
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