Tuesday, April 19, 2016

Hidden Genetic Mutations in Stem Cells Could Weaken Therapeutic Benefit

A microscopic image of human induced pluripotent stem cells (iPS). 

Mutations in mitochondrial DNA occur more frequently in individual cells as the human body ages. Since there are thousands of mitochondrial mutations and most of them are hidden, researchers have a hard time identifying all of the mutations present in a sample of a blood or piece of skin. However, researchers are able to distinguish the mutations easier if they are in iPS cells. In order to identify these mutations, iPS cells undergo a process where they are cloned in skin or blood cells which results in a iPS cell line that contains the same mitochondrial DNA mutations as the original adult cell. 

In a study conducted by Shoukhrat Mitalipov, director of the Center for Embryonic Cell and Gene Therapy at Oregon Health and Science University, researchers analyzed mitochondrial DNA mutations in 20 iPS cloned cell lines per patient that were obtained from blood and skin samples from healthy people and people suffering from degenerative diseases. When the iPS cell lines were sequenced, the researchers discovered that there was a significantly high number of mitochondrial mutations in the cells of patients who were over 60 years old. Based off of the results, the researchers observed that the larger the number of mutations in mitochondrial DNA caused a greater compromise to be made in the cells functions. Additionally, any defects in the mitochondria can potentially weaken or diminish the iPS cells ability to repair damaged tissues and organs. From this study the team of researchers discovered that iPS cells, specifically a type of stem cell from blood or skin sample, contain mutated mitochondrial DNA. In order to effectively use iPS cells to their full potential in humans, medical geneticist Taosheng Huang suggests that doctors and researchers need to check first if there are any mutations in the mitochondrial genome (Oregon Health and Science University 2016). 

I think that potential therapies involving the use of iPS stem cells can be used to treat diseases that occur with old- age. In the article, Mitalipov expressed that "pathogenic mutations in our mitochondrial DNA have long been thought to be a driving force in aging and age- onset diseases, though clear evidence was missing. Now with that evidence at hand, we know that we must screen stem cells for mutations or collect them at a younger age to ensure their mitochondrial genes are healthy" (Oregon Health and Science University 2016). In my opinion, I think the background knowledge of how cells are damaged with old age can serve as a basis for future studies to further examine how mutations in the mitochondria play a role in degenerative diseases. 

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