The approval of a new treatment method by which three parents will be able to beget a child is being discussed since a few years in Great Britain and will possibly become a reality in two years.
The method is supposed to help in eliminating the mother's genetic defects already in the test tube. The defect lies in so-called mitochondria, the "power houses" of cells. To get rid of defective mitochondria the nucleus of one egg cell has to be transferred to another egg cell bearing intact mitochondria. Scientists at the Vetmeduni Vienna show for the first time that even a few defective mitochondria dragged along in the transfer could cause diseases.
The results were published in Cell Reports.
Mitochondria are cell organelles located within animal and human cells. They produce energy for the organism, possess their own genetic material - mitochondrial DNA (mtDNA) - and are transmitted exclusively by the mother. Depending on their activity and tasks, different numbers of mitochondria are present in a cell - usually a few hundred to a thousand per body cell.
Inherited mitochondrial disorders or so-called mitochondropathies occur in about one of 10,000 humans throughout the world. Diseases such as diabetes, stroke, cardiac defects, epilepsy, or muscle weakness may originate from mitochondrial defects. Inherited mitochondrial disorders have been incurable so far. Therefore, efforts are now being made to enable women with this disease to bear healthy children by means of nuclear transfer.
Mitochondria multiply at different rates
Jörg Burgstaller, a scientist and member of Gottfried Brem's research group at the Vetmeduni Vienna, has been working for several years on the genetics of mitochondria. It was known before that different types of mitochondria within a cell can proliferate at different rates. However, it was not known whether this is a singular phenomenon or if these cases occur more frequently.
Burgstaller investigated this in four newly bred mouse models which carried different mixtures of mitochondria whose DNA were related to each other to a differing extent. This meant no health problem for the mice since all mtDNAs are were fully functional.
The outcome was: the more distantly two types of mitochondria within an egg cell were related, the more frequently a growth advantage was noted in favor of one of the two types of mitochondria. When two different mtDNAs were equally common in cells of an organ at the time of birth, one type was completely lost after a while. One mitochondria variant had thus achieved a growth advantage compared to the other variant and superseded the latter. This effect was almost non-existent in genetically very similar mitochondria within the cells; the ratio between the two types of mitochondria was not altered in that case.
The effect is of significance in reproduction medicine
Burgstaller's results may have effects on the planned introduction of the so called "Three-Parent Baby" in Great Britain. Experts take the cell nucleus of one human egg cell whose mitochondria have a defect and place it in an egg cell with "healthy" mitochondria. The baby resulting from this procedure has three parents, namely the mother whose cell nucleus is used, the mother whose mitochondria are involved, and the father whose sperm inseminated the egg cell.
However, this method raises the following problem: in every nuclear transfer, a small number of defective mitochondria are transferred into the healthy egg cell. "So far it was believed that this minimal ‘contamination’ is of no consequence for the baby. However, our data show that the effect may have dramatic consequences on the health of the offspring. If the mitochondria of both mothers are genetically very different, it may have the same effects seen in the mouse model," says Burgstaller who developed the theory together with co-author Joanna Poulton, Professor of Mitochondrial Genetics at the John Radcliffe Hospital in Oxford. "One mitochondrial type may be able to assert itself against the other. If the assertive one happens to carry the defective mtDNA, the benefit of the therapy would be jeopardized."
The solution to the "Three-Parent Baby"-problem
Burgstaller and his colleagues suggest the following solution to the problem: the mtDNA of both mothers, i.e. the donor of the nucleus and the donor of the mitochondria, should be analyzed in advance and aligned to each other. So called “machting haplotypes” could prevent the dangerous effect. In the future the effect may even be utilized in a targeted manner to suppress defective mtDNA.
The work was conducted in cooperation with BIAT (Biomodels Austria) and the technology platform Vetcore at Vetmeduni Vienna, Joanna Poulton from John Radcliffe Hospital in Oxford, Jaroslav Piálek from the Czech Academy of Sciences, and Iain Johnston and Nick Jones from the Imperial College (London).
The article „mtDNA Segregation in Heteroplasmic Tissues Is Common In Vivo and Modulated by Haplotype Differences and Developmental Stage”, by Joerg Patrick Burgstaller, Iain G. Johnston, Nick S. Jones, Jana Albrechtová, Thomas Kolbe, Claus Vogl, Andreas Futschik, Corina Mayrhofer, Dieter Klein, Sonja Sabitzer, Mirjam Blattner, Christian Gülly, Joanna Poulton, Thomas Rülicke, Jaroslav Piálek, Ralf Steinborn and Gottfried Brem was published in the journal Cell Reports. DOI: 10.1016/j.celrep.2014.05.020 http://www.sciencedirect.com/science/article/pii/S2211124714003957
About the University of Veterinary Medicine, Vienna
The University of Veterinary Medicine, Vienna in Austria is one of the leading academic and research institutions in the field of Veterinary Sciences in Europe. About 1,200 employees and 2,300 students work on the campus in the north of Vienna which also houses five university clinics and various research sites. Outside of Vienna the university operates Teaching and Research Farms. http://www.vetmeduni.ac.at
Dr. Joerg Burgstaller
University of Veterinary Medicine Vienna (Vetmeduni Vienna)
T +43 1 25077-5639
M +43 664 3767262
Science Communication / Public Relations
University of Veterinary Medicine Vienna (Vetmeduni Vienna)
T +43 1 25077-1153
Dr. Susanna Kautschitsch | idw - Informationsdienst Wissenschaft
Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München
Second research flight into zero gravity
21.10.2016 | Universität Zürich
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences