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Can the negative effects of vitrification on oocyte developmental competence be mitigated?

      I read with interest the article by
      • Bonte D.
      • Thys V.
      • De Sutter P.
      • Boel A.
      • Leybaert L
      • Heindryckx B.
      Vitrification negatively affects the Ca2+-releasing and activation potential of mouse oocytes, but vitrified oocytes are potentially useful for diagnostic purposes.
      showing that vitrification affects oocyte Ca2+-releasing and activation potential negatively in a mouse model. Similar patterns of Ca2+ signaling abnormalities in response to sperm were previously reported in human vitrified-warmed oocytes (
      • Nikiforaki D.
      • Vanden Meerschaut F.
      • Qian C.
      • De Croo I.
      • Lu Y.
      • Deroo T.
      • Van den Abbeel E.
      • Heindryckx B.
      • De Sutter P.
      Oocyte cryopreservation and in vitro cultura affect calcium signalling during human fertilization.
      ) and may cause epigenetic abnormalities, sometimes detectable relatively late in postnatal life (
      • Tesarik J.
      Paternal effects on embryonic, fetal and offspring health: the role of epigenetics in the ICSI and ROSI era.
      ).
      With fresh oocytes, abnormalities of oocyte Ca2+ signaling after intracytoplasmic sperm injection (ICSI) can be caused by an inadequate stimulus from the fertilizing spermatozoon and also by insufficiencies of the oocyte response mechanims. Normal fertilization can be achieved by assisted oocyte activation (AOA) in both of these circumstances (
      • Rybouchkin A.V.
      • Van der Straeten F.
      • Quatacker J.
      • De Sutter P.
      • Dhont M.
      Fertilization and pregnancy after assisted oocyte activation and intracytoplasmic sperm injection in a case of round-headed sperm associated with deficient oocyte activation capacity.
      ;
      • Tesarik J.
      • Rienzi L.
      • Ubaldi F.
      • Mendoza C.
      • Greco E.
      Use of a modified intracytoplasmic sperm injection technique to overcome sperm-borne and oocyte-borne oocyte activation failures.
      ). Oocyte activation can be assisted by a calcium ionophore (
      • Rybouchkin A.V.
      • Van der Straeten F.
      • Quatacker J.
      • De Sutter P.
      • Dhont M.
      Fertilization and pregnancy after assisted oocyte activation and intracytoplasmic sperm injection in a case of round-headed sperm associated with deficient oocyte activation capacity.
      ) or by enhancing Ca2+ entry into the oocyte from the surrounding culture medium with the use of a modified ICSI technique (
      • Tesarik J.
      • Rienzi L.
      • Ubaldi F.
      • Mendoza C.
      • Greco E.
      Use of a modified intracytoplasmic sperm injection technique to overcome sperm-borne and oocyte-borne oocyte activation failures.
      ). With both of these methods, the excess Ca2+ entering the oocyte is thought to replenish the Ca2+ stores, compensating for previous depletion, reported to be caused by oocyte exposure to cryoprotective agents (CPA) used in vitrification/warming procedures (
      • Bonte D.
      • Thys V.
      • De Sutter P.
      • Boel A.
      • Leybaert L
      • Heindryckx B.
      Vitrification negatively affects the Ca2+-releasing and activation potential of mouse oocytes, but vitrified oocytes are potentially useful for diagnostic purposes.
      ).
      Improvements of CPA that prevent Ca2+ losses from the oocyte stores may resolve the problem in the future. Until then, the use of AOA-ICSI could be considered for existing vitrified oocytes, especially in cases of suspected sperm abnormalities that might further compromise embryo development.

      References

        • Bonte D.
        • Thys V.
        • De Sutter P.
        • Boel A.
        • Leybaert L
        • Heindryckx B.
        Vitrification negatively affects the Ca2+-releasing and activation potential of mouse oocytes, but vitrified oocytes are potentially useful for diagnostic purposes.
        Reprod. Biomed. Online. 2020; 40: 13-24
        • Nikiforaki D.
        • Vanden Meerschaut F.
        • Qian C.
        • De Croo I.
        • Lu Y.
        • Deroo T.
        • Van den Abbeel E.
        • Heindryckx B.
        • De Sutter P.
        Oocyte cryopreservation and in vitro cultura affect calcium signalling during human fertilization.
        Hum. Reprod. 2014; 29: 29-40
        • Rybouchkin A.V.
        • Van der Straeten F.
        • Quatacker J.
        • De Sutter P.
        • Dhont M.
        Fertilization and pregnancy after assisted oocyte activation and intracytoplasmic sperm injection in a case of round-headed sperm associated with deficient oocyte activation capacity.
        Fertil. Steril. 1997; 68: 1144-1147
        • Tesarik J.
        • Rienzi L.
        • Ubaldi F.
        • Mendoza C.
        • Greco E.
        Use of a modified intracytoplasmic sperm injection technique to overcome sperm-borne and oocyte-borne oocyte activation failures.
        Fertil. Steril. 2002; 78: 619-624
        • Tesarik J.
        Paternal effects on embryonic, fetal and offspring health: the role of epigenetics in the ICSI and ROSI era.
        IntechOpen. 2019; https://doi.org/10.5772/intechopen.88589