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Concise reviews: Assisted reproductive technologies to prevent transmission of mitochondrial DNA disease.

Richardson J, Irving L, Hyslop LA, Choudhary M, Murdoch A, Turnbull DM, Herbert M - Stem Cells (2015)

Bottom Line: The available evidence indicates that cells removed from an eight-cell embryo are predictive of the mutation load in the entire embryo, indicating that PGD provides an effective risk reduction strategy for women who produce embryos with low mutation loads.For those who do not, research is now focused on meiotic nuclear transplantation techniques to uncouple the inheritance of nuclear and mtDNA.The scientific progress and associated regulatory issues are discussed.

View Article: PubMed Central - PubMed

Affiliation: Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.

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Schematic drawing showing approaches to meiotic genome transfer that has been tested in human oocytes/zygotes for potential clinical application to reduce the risk of transmitting mtDNA disease. (A): Pronuclear transfer: MII-arrested oocytes obtained from the affected woman and a healthy donor are fertilized and the pronuclei are transferred in a karyoplast from the affected woman's fertilized egg to the enucleated donor egg. (B): Spindle transfer: oocytes obtained from an affected woman and a healthy donor are enucleated by removal of the MII spindle and its chromosomes in a karyoplast. The karyoplast from the affected woman is fused with the enucleated oocyte from the healthy donor. Reconstituted oocytes are then fertilized and undergo the second meiotic division followed by formation of the male and female pronuclei. Abbreviations: MII, second meiotic division; PN, pronuclei.
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fig02: Schematic drawing showing approaches to meiotic genome transfer that has been tested in human oocytes/zygotes for potential clinical application to reduce the risk of transmitting mtDNA disease. (A): Pronuclear transfer: MII-arrested oocytes obtained from the affected woman and a healthy donor are fertilized and the pronuclei are transferred in a karyoplast from the affected woman's fertilized egg to the enucleated donor egg. (B): Spindle transfer: oocytes obtained from an affected woman and a healthy donor are enucleated by removal of the MII spindle and its chromosomes in a karyoplast. The karyoplast from the affected woman is fused with the enucleated oocyte from the healthy donor. Reconstituted oocytes are then fertilized and undergo the second meiotic division followed by formation of the male and female pronuclei. Abbreviations: MII, second meiotic division; PN, pronuclei.

Mentions: The technique of pronuclear transfer (PNT) between fertilized mouse eggs (zygotes) was pioneered by McGrath and Solter more than 3 decades ago 35. The procedure involves treatment of zygotes with microtubule and actin-depolymerizing drugs to facilitate removal of the pronuclei without the need to penetrate the plasma membrane. The PN are pinched-off within a small volume of membrane-enclosed cytoplasm, known as a karyoplast, which is subsequently fused with an enucleated zygote. Membrane fusion is facilitated by inactivated Sendai virus or an electrical pulse 35,36. However, the latter is not well tolerated by human oocytes and zygotes 37,38. The experiments of McGrath and Solter 35 revealed that PNT between zygotes from different mouse strains can produce healthy and normally reproducing offspring. The possibility of using PNT to prevent transmission of mtDNA disease (Fig. 2A) was first proposed in the 1990s 21. Later experiments using zygotes from a mouse carrying a rearrangement in the mtDNA indicated that the fraction of mutant mtDNA could be greatly reduced by PN transfer into enucleated zygotes from females with wild-type mtDNA 21. More recently, proof of concept experiments with abnormally fertilized eggs explored the potential of PNT in human zygotes 38. Despite their large size (25–30 µm), transplantation of PN between human zygotes was technically feasible and compatible with development to the blastocyst stage 38. After optimization of the procedure, the level of the mtDNA “carried-over” within the karyoplast was reduced to <2% on average 38, which is well below the disease threshold for mutations studied to date 14.


Concise reviews: Assisted reproductive technologies to prevent transmission of mitochondrial DNA disease.

Richardson J, Irving L, Hyslop LA, Choudhary M, Murdoch A, Turnbull DM, Herbert M - Stem Cells (2015)

Schematic drawing showing approaches to meiotic genome transfer that has been tested in human oocytes/zygotes for potential clinical application to reduce the risk of transmitting mtDNA disease. (A): Pronuclear transfer: MII-arrested oocytes obtained from the affected woman and a healthy donor are fertilized and the pronuclei are transferred in a karyoplast from the affected woman's fertilized egg to the enucleated donor egg. (B): Spindle transfer: oocytes obtained from an affected woman and a healthy donor are enucleated by removal of the MII spindle and its chromosomes in a karyoplast. The karyoplast from the affected woman is fused with the enucleated oocyte from the healthy donor. Reconstituted oocytes are then fertilized and undergo the second meiotic division followed by formation of the male and female pronuclei. Abbreviations: MII, second meiotic division; PN, pronuclei.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4359624&req=5

fig02: Schematic drawing showing approaches to meiotic genome transfer that has been tested in human oocytes/zygotes for potential clinical application to reduce the risk of transmitting mtDNA disease. (A): Pronuclear transfer: MII-arrested oocytes obtained from the affected woman and a healthy donor are fertilized and the pronuclei are transferred in a karyoplast from the affected woman's fertilized egg to the enucleated donor egg. (B): Spindle transfer: oocytes obtained from an affected woman and a healthy donor are enucleated by removal of the MII spindle and its chromosomes in a karyoplast. The karyoplast from the affected woman is fused with the enucleated oocyte from the healthy donor. Reconstituted oocytes are then fertilized and undergo the second meiotic division followed by formation of the male and female pronuclei. Abbreviations: MII, second meiotic division; PN, pronuclei.
Mentions: The technique of pronuclear transfer (PNT) between fertilized mouse eggs (zygotes) was pioneered by McGrath and Solter more than 3 decades ago 35. The procedure involves treatment of zygotes with microtubule and actin-depolymerizing drugs to facilitate removal of the pronuclei without the need to penetrate the plasma membrane. The PN are pinched-off within a small volume of membrane-enclosed cytoplasm, known as a karyoplast, which is subsequently fused with an enucleated zygote. Membrane fusion is facilitated by inactivated Sendai virus or an electrical pulse 35,36. However, the latter is not well tolerated by human oocytes and zygotes 37,38. The experiments of McGrath and Solter 35 revealed that PNT between zygotes from different mouse strains can produce healthy and normally reproducing offspring. The possibility of using PNT to prevent transmission of mtDNA disease (Fig. 2A) was first proposed in the 1990s 21. Later experiments using zygotes from a mouse carrying a rearrangement in the mtDNA indicated that the fraction of mutant mtDNA could be greatly reduced by PN transfer into enucleated zygotes from females with wild-type mtDNA 21. More recently, proof of concept experiments with abnormally fertilized eggs explored the potential of PNT in human zygotes 38. Despite their large size (25–30 µm), transplantation of PN between human zygotes was technically feasible and compatible with development to the blastocyst stage 38. After optimization of the procedure, the level of the mtDNA “carried-over” within the karyoplast was reduced to <2% on average 38, which is well below the disease threshold for mutations studied to date 14.

Bottom Line: The available evidence indicates that cells removed from an eight-cell embryo are predictive of the mutation load in the entire embryo, indicating that PGD provides an effective risk reduction strategy for women who produce embryos with low mutation loads.For those who do not, research is now focused on meiotic nuclear transplantation techniques to uncouple the inheritance of nuclear and mtDNA.The scientific progress and associated regulatory issues are discussed.

View Article: PubMed Central - PubMed

Affiliation: Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.

Show MeSH
Related in: MedlinePlus