Related Experiment Video
Updated: Dec 16, 2025
Genotyping Single Nucleotide Polymorphisms in the Mitochondrial Genome by Pyrosequencing
Published on: February 10, 2023
High throughput single cell analysis of mitochondrial heteroplasmy in mitochondrial diseases
Ryotaro Maeda1, Daisuke Kami2, Hideki Maeda1
1Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465, Kajii cho, Kamigyo ku, Kyoto, 802-8566, Japan.
Abstract:
Mitochondrial heteroplasmy, which fundamentally means intracellular heterogeneity of mitochondrial DNA (mtDNA), has been measured in a group of cells, regardless of intercellular heterogeneity. Ordinal methods for mitochondrial heteroplasmy cannot discriminate between an intercellular homogenic population composed of cells with similar intracellular heterogeneity for mtDNA and an intercellular heterogenic population composed of cells with different rates of mutated mtDNA. A high-throughput method to determine mitochondrial heteroplasmy in a single cell was developed by using droplet digital PCR with TaqMan polymerase in this study. This technique revealed that there are three different cell populations of cultured fibroblasts derived from patients with mitochondrial disease carrying a mutation in the mtDNA; cells with homoplasmy of either mutated or healthy mtDNA; and cells mixed with mutated and healthy mtDNA. The presence of intercellular heterogeneity, even in uniformed cultured fibroblasts, suggests that heterogeneity should exist among different kinds of cells. The diagnosis of intercellular heterogeneity with respect to mitochondrial heteroplasmy by this methodology could provide novel insight into developing a treatment strategy for mitochondrial diseases.
Insights
New droplet digital PCR accurately measures mitochondrial heteroplasmy in single cells. This method distinguishes cell populations, aiding mitochondrial disease research and treatment strategies.
Area of Science:
- Genetics
- Cell Biology
- Biochemistry
Background:
- Mitochondrial heteroplasmy, or intracellular variation in mitochondrial DNA (mtDNA), is crucial for understanding mitochondrial diseases.
- Existing methods struggle to differentiate between cells with uniform or varied levels of mutated mtDNA, hindering accurate diagnosis.
Purpose of the Study:
- To develop a high-throughput method for quantifying mitochondrial heteroplasmy at the single-cell level.
- To differentiate between intercellular homogeneity and heterogeneity in mtDNA mutation rates.
Main Methods:
- Utilized droplet digital PCR (ddPCR) with TaqMan polymerase for high-throughput single-cell analysis.
- Applied the method to cultured fibroblasts from patients with mitochondrial disease carrying mtDNA mutations.
Main Results:
- Successfully identified three distinct cell populations: homoplasmic for healthy mtDNA, homoplasmic for mutated mtDNA, and heteroplasmic with both.
- Demonstrated intercellular heterogeneity in mtDNA mutation rates even within uniform fibroblast cultures.
Conclusions:
- The developed ddPCR method accurately diagnoses intercellular heterogeneity in mitochondrial heteroplasmy.
- Findings suggest widespread cellular heterogeneity in mtDNA, impacting mitochondrial disease progression.
- This methodology offers novel insights for developing targeted treatment strategies for mitochondrial disorders.
