Neca% FINDIKLI, M.Sc., Ph.D.
Director of IVF Laboratories
Bahceci Women’s Health Group, Turkey
SCNT and IVF
Novel Approaches for Trea%ng Mitochondrial Diseases
Mitochondria -‐ Biology 101
• mtDNA muta%ons are an important cause of human disease, with > 400 known
pathogenic mtDNA muta%ons or dele%ons to date.
• Studies es%mate that at least 1 in 5000 working age individuals harbors an mtDNA muta%on.
• Carrier frequency at birth is 1:200 for the most common mtDNA point muta%ons.
• mtDNA muta%ons accumulate with age in a number of %ssues and cause respiratory-‐
chain deficiency in those cells with a high muta%on load.
Mitochondria -‐ Biology 101
• Mitochondria produce ATP through OXPHOS, but are also key players in apoptosis, calcium storage and iron–sulfur cluster biogenesis.
• mtDNA is a 16.6 kb, double-‐stranded, circular genome.
• mtDNA replicates independently from the cell cycle, but the exact mechanism for mtDNA replica%on is s%ll to be determined.
• Of the es%mated around 1500 genes required for mitochondrial func%on in humans, only 37 are encoded by the mtDNA itself (13 polypep%des, 2 rRNAs and 22 tRNAs).
Mitochondria -‐ Biology 101
Mitochondria in reproduc%ve medicine
mtDNA copy number 10,000 – 700,000 mtDNA copy number
100
Mitochondrial boaleneck
Mitochondria in reproduc%ve medicine
Mitochondrial boaleneck
Stewart and Chinnery. 2015-‐Nature Reviews
• Remain childless
• Adop%on
• Accept a high risk for clinically manifest mtDNA disease in the offspring
• Oocyte dona%on
• Preimplanta%on Gene%c Diagnosis
• Prenatal diagnosis
• Mitochondrial replacement
• Maternal spindle transfer
• Pronuclear transfer
Possible approaches from reproduc%on perspec%ve
Mitochondrial replacement techniques
Falk et al. 2016-‐NEJM
Mitochondrial replacement techniques
Falk et al. 2016-‐NEJM
“Nuclear transplanta.on in the mouse embryo by microsurgery and cell fusion”
McGrath J and Solter D. (1983)
Transplanta%on of genome
Maternal spindle transfer
Tachibana et al. 2009-‐Nature Non-‐human primate
Maternal spindle transfer
Tachibana et al. 2009-‐Nature Non-‐human primate
Maternal spindle transfer
Tachibana et al. 2013-‐Nature Human/Non-‐human primate
Tachibana et al. 2013-‐Nature
Maternal spindle transfer
Premature oocyte ac%va%on
(Some ST oocytes were found to be already progressed to late anaphase II)
Tachibana et al. 2013-‐Nature
Maternal spindle transfer
Human/Non-‐human primate
Paull et al. 2013-‐Nature
Maternal spindle transfer
Human
Maternal spindle transfer
Paull et al. 2013-‐Nature Human
Pronuclear transfer
Sato et al. 2005-‐PNAS Mice
Recipients
Donors
Pronuclear transfer
Sato et al. 2005-‐PNAS Mice
Pronuclear transfer
Craven et al. 2010-‐Nature Human
Pronuclear transfer
Craven et al. 2010-‐Nature Human
What do mtDNA muta%on carriers think?
Engelstad et al., 2016-‐Hum. Reprod.
Engelstad et al., 2016-‐Hum. Reprod.
What do mtDNA muta%on carriers think?
Engelstad et al., 2016-‐Hum. Reprod.
What do oocyte donors think?
• Ethics
• Nuffield Council on Bioethics
• Legality and the regula%on of the technique
• Public enquiry à House of parliamentà HFEA à
Individual licence applica%ons by the clinics
• Safety
• Panels of independent experts. (Found no reason to believe that these techniques would not be safe)
• Efficacy
Four Big Challenges: UK experience
Near Future?
Folmes et al., 2016
Near Future?
Folmes et al., 2016
Near Future?
• “It is rare that any new technique has undergone such extensive public and scien%fic debate, and of course, there will always be those opposed to such advances on either ethical or scien%fic grounds.
• However, we believe that it is really important to remember why these techniques are being proposed and that ul%mately we do hope that women with mtDNA disease will be able to make reproduc%ve choices that include the possiblity that their own offspring free from disease”
Conclusion
Herbert and Turnbull, 2015-‐EMBO Reports
