Human fibroblasts derived from embryonic stem cells showing nuclei (blue) and mitochondria (red)SHOUKHRAT MITALIPOVThe number of mutations in mitochondrial DNA (mtDNA) could vary substantially between different lines of induced pluripotent stem cells (iPSCs), according to a study published last week (April 14) in Cell Stem Cell. The findings suggest the need to screen mtDNA for mutations before iPSCs are used in the clinic.
“People tend to look just at the nuclear genome,” study coauthor Taosheng Huang of Cincinnati Children’s Hospital said in a statement. “But if you want to use iPS cells in a human, you must check for mutations in the mitochondrial genome.”
To investigate the frequency of mitochondrial defects in adult somatic cells, the team measured the number of mtDNA mutations in skin and blood samples donated by a 72-year-old volunteer. When cells were pooled for analysis, the researchers identified relatively low levels of mitochondrial defects. But when they picked individual cells at random, they found much higher levels of mutations, which were masked when analyzed as part of whole tissues due to cell heterogeneity.
“We call it the freckled effect,” Huang explained in the statement. ...
