Open AccessDisease‐Causing Mitochondrial Heteroplasmy Segregated Within Induced Pluripotent Stem Cell Clones Derived from a Patient with MELAS
Author(s) -
Folmes Clifford D.L.,
MartinezFernandez Almudena,
PeralesClemente Ester,
Li Xing,
Mcdonald Amber,
Oglesbee Devin,
Hrstka Sybil C.,
PerezTerzic Carmen,
Terzic Andre,
Nelson Timothy J.
Publication year - 2013
Publication title -
stem cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.159
H-Index - 229
eISSN - 1549-4918
pISSN - 1066-5099
DOI - 10.1002/stem.1389
Subject(s) - heteroplasmy , biology , induced pluripotent stem cell , stem cell , disease , melas syndrome , mitochondrial dna , mitochondrion , genetics , cell , mitochondrial disease , reprogramming , microbiology and biotechnology , mitochondrial myopathy , gene , embryonic stem cell , pathology , medicine
Mitochondrial diseases display pathological phenotypes according to the mixture of mutant versus wild‐type mitochondrial DNA (mtDNA), known as heteroplasmy. We herein examined the impact of nuclear reprogramming and clonal isolation of induced pluripotent stem cells (iPSC) on mitochondrial heteroplasmy. Patient‐derived dermal fibroblasts with a prototypical mitochondrial deficiency diagnosed as mitochondrial encephalomyopathy with lactic acidosis and stroke‐like episodes (MELAS) demonstrated mitochondrial dysfunction with reduced oxidative reserve due to heteroplasmy at position G13513A in the ND5 subunit of complex I. Bioengineered iPSC clones acquired pluripotency with multilineage differentiation capacity and demonstrated reduction in mitochondrial density and oxygen consumption distinguishing them from the somatic source. Consistent with the cellular mosaicism of the original patient‐derived fibroblasts, the MELAS‐iPSC clones contained a similar range of mtDNA heteroplasmy of the disease‐causing mutation with identical profiles in the remaining mtDNA. High‐heteroplasmy iPSC clones were used to demonstrate that extended stem cell passaging was sufficient to purge mutant mtDNA, resulting in isogenic iPSC subclones with various degrees of disease‐causing genotypes. On comparative differentiation of iPSC clones, improved cardiogenic yield was associated with iPSC clones containing lower heteroplasmy compared with isogenic clones with high heteroplasmy. Thus, mtDNA heteroplasmic segregation within patient‐derived stem cell lines enables direct comparison of genotype/phenotype relationships in progenitor cells and lineage‐restricted progeny, and indicates that cell fate decisions are regulated as a function of mtDNA mutation load. The novel nuclear reprogramming‐based model system introduces a disease‐in‐a‐dish tool to examine the impact of mutant genotypes for MELAS patients in bioengineered tissues and a cellular probe for molecular features of individual mitochondrial diseases. S TEM C ells 2013;31:1298–1308