Stem cell hope for mitochondrial disease sufferers

17 July 2015

Stem cells in the future could improve the lives of people suffering from debilitating mitochondrial disease.

One in every 6,500 babies has severe mitochondrial disease which can cause muscle weakness, liver disease, diabetes, seizures, developmental delays or vision problems. Mitochondrial disease arises from genetic defects heritable through the maternal line that impair the function of the mitochondria, the cellular energy-producing structures. Currently there are no treatments for patients with the condition. 

An international collaboration of scientists has used two different but complementary cell reprogramming methods to generate disease-free stem cells. The hope eventually is to generate enough healthy stem cells from a patient’s skin, which can then be transplanted back into the patient to restore the energy supply to the most affected tissues, to repair defective organs. The researchers believe this is a crucial step towards developing therapies for patients and a boon to basic research into the disease. 

Study lead, Shoukhrat Mitalipov of the Oregon Health and Science University said: "To families with a loved one born with a mitochondrial disease waiting for a cure, today we can say that a cure is on the horizon”.

Published in Nature, the team collected skin samples from patients with mitochondrial encephalomyopathy (Leigh Syndrome). Following current standard protocols they converted skin cells into pluripotent stem cells- cells that have the potential to differentiate into any cell in the body.

Mitochondrial disease may comprise a mixture of unhealthy and healthy mitochondria within cells, with the possibility that some cells contain no faulty DNA. The first method relies on these healthy cells, but they are not always present. This led the scientists to explore a second approach, wherein the nucleus of a skin cell – which contains most of the genes – was moved into a donor egg cell with healthy mitochondria. Following this method, pluripotent stem cells with healthy mitochondria were created.

A benefit of using combined gene and cell therapy for mitochondrial disease treatment, over unmatched tissue or organ donations, will be that it is the patient’s own healthy tissue so will not be rejected by the patient’s bodies, according to Mitalipov.

Researchers can currently use the healthy pluripotent stem cells to generate heart, brain, muscle or eye cells however they still are exploring methods to make those cells fully mature and functional and transplant them into patients.

Dusto Ilic, a stem cell expert at King’s College London said: “Given the complexity of the technology, costs and risks involved, the strategies described here will remain a proof-of-concept and unlikely see a practical use in clinical medicine”.

Earlier this year the UK made the landmark decision to allow the creation of embryos from three people to prevent children being born with mitochondrial disease. These new approaches offer a way forward in treatments for people living with this disorder.

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