Eukaryotic cell organelles

Inheritance Each cell has MANY mitochondria Oocytes have many mitochondria Sperm mitochondria are specialized, jettisoned at fertilization Mitochondria are only MATERNALLY inherited

Mitochondrial Function Energy production- via Krebs Cycle  ATP Glucose  pyruvate = 2 ATP Pyruvate  CO 2 and H 2 0 = ATP Calcium homeostasis Role in apoptosis Role in blood and hormone synthesis Main tissues with high energy needs Brain, heart, liver, muscles, respiratory, endocrine

Human mitochondrial genome Nageswara R. Madamanchi, and Marschall S. Runge Circulation Research. 2007;100: Copyright © American Heart Association, Inc. All rights reserved. 37 genes ~17,000 bp 13 polypeptides, 22 tRNAs, 2 rRNAs).

Mitochondrial Dysfunction Loss of motor control Muscle weakness Seizures Visual and auditory problems Poor growth Cardiac disease Liver disease Developmental delays Susceptibility to Infection

Variants in mitochondrial genes variety of diseases 1 in live births has a potentially pathogenic mitochondrial DNA mutation Often delayed onset Not directly lethal 45 listed on site- United Mitochondrial Disease Foundation diseases of mitochondrial function -

Could Replacement of Mom’s Mitochondria Repair the Problem? During Female embryonic development After puberty At each cycle

Overview of spindle- chromosomal complex transfer Video mms://media.ohsu.edu/host/hosp/replacement.wmv Healthy Baby

IVF required for embryo development (Photo Credit: Mr. J. Conaghan) PlacentaEmbryo

Mitochondria appear everywhere except near the chromosomes

Visualization of the spindle during enucleation avoids damage

Spindle-chromosomal complex successfully isolated

Karyoplast contains ~1.5% volume compared to a cytoplast

Karyoplast inserted into perivitelline space Karyoblast with patient’s spindle

Fusion using Sendai virus extract yields metaphase II chromosomes

Movie mms://media.ohsu.edu/host/hosp/replacement.wmv

Chronology of innovation Late 1990s: Cytoplasmic transfer leads to ~100 births worldwide 2001: FDA halts cytoplasmic transfer September 2009: Mitochondrial gene replacement in primate offspring and embryonic stem cells May 2010: Pronuclear transfer in non-viable human embryos October 2012: Mitochondrial gene replacement in human embryos to blastocyst stage January 2013: Two additional studies demonstrating feasibility in human

Success rate: 4 healthy births Mito and Tracker

15 spindle-transfer embryos implanted into 9 recipients

Sequencing confirms mixed parentage

Pronuclea r transfer is an alternate approach

Some mitochondria may also be transferred