Development and discovery of treatments for mitochondrial disease

Abstract

Although mitochondrial disorders are the most common inherited form of neuromuscular disease, there are currently limited effective treatments that directly improve mitochondrial function – either by modulation of the effects of mutated genes or by increasing the proportion of healthy mitochondria. In this work, two different approaches were employed to develop treatments for mitochondrial diseases: the design of mitochondrially targeted anti-sense oligonucleotides and the development of a high throughput screen of a unique library of bacterial extracts. The heteroplasmic nature of mitochondrial DNA (mtDNA) enables the use of anti-genomic strategies to specifically prevent the replication, transcription or translation of mutated molecules of mtDNA or mitochondrial mRNA in patients with heteroplasmic mtDNA mutations. In conjunction with an industrial partner (Ugichem GmbH), a mitochondrial targeting oligonucleotide was developed using cell membrane crossing oligomers (CMCOs) – a new class of oligonucleotide with the ability to enter and accumulate within the cytoplasm. By conjugating “mitochondrial targeting” molecules to the CMCOs, translocation to mitochondria was shown, potentially enabling the use of anti-sense therapies in the treatment of mtDNA diseases. To complement the mutation specific approach of anti-sense oligonucleotide therapies a large scale screen was carried out to discover compounds that could cause a general improvement in mitochondrial function. A library of unique bacterial extracts, provided by Demuris Ltd, was screened for effects on mitochondrial biogenesis in HeLa cells. To that end, a high throughput assay, which used fluorescent markers to detect changes in relative mitochondrial mass, was designed and validated using mitochondrially active control compounds. The screen of bacterial extracts discovered several one extract which caused mitochondrial mass to increase 2 fold after 48 hours incubation.