Blood stem cells from healthy individuals exhibit significant chromosomal alterations, indicating widespread genetic mosaicism, according to a recent study by EMBL and the Max Delbrück Center.
EMBL and Max Delbrück Center Researchers Uncover Extensive Genetic Variability in Healthy Cells
In a study led by Jan Korbel from the European Molecular Biology Laboratory (EMBL) and Ashley Sanders from the Berlin Institute for Medical Systems Biology of the Max Delbrück Center (MDC-BIMSB), researchers have discovered that roughly one in 40 human bone marrow cells harbor substantial chromosomal alterations, such as copy number variations and chromosomal rearrangements. Remarkably, these alterations do not result in any observable disease or abnormality. Furthermore, cell samples from individuals over the age of 60 exhibited a higher incidence of cells with genomic alterations, suggesting a novel mechanism potentially contributing to aging-related diseases. These findings were recently published in Nature Genetics.
“The study highlights that we are all mosaics,” stated Korbel, Senior Scientist in the Genome Biology Unit and Head of Data Science at EMBL Heidelberg. “Even so-called normal cells carry all sorts of genetic mutations. Ultimately, this means that there are more genetic differences between individual cells in our bodies than between different human beings.”
Korbel and Sanders, Group Leader at the Max Delbrück Center, investigate how genetic structural variation, including deletions, duplications, inversions, and translocations of large genome sections, influence disease development. In oncology, it is well-documented that genetic mutations can cause cells to grow uncontrollably, leading to tumor formation. “We are applying similar concepts to understand how non-cancerous diseases develop,” Sanders explained.
Innovative Single-Cell Sequencing Technology: Strand-Seq
The discovery was made possible through a cutting-edge single-cell sequencing technology known as Strand-seq. This unique DNA sequencing technique unveils intricate genomic details in single cells that other methods fail to detect. Sanders played a pivotal role in the development of Strand-seq, refining the protocol during her doctoral research and postdoctoral fellowship in Korbel’s lab.
Strand-seq enables researchers to detect structural variants in individual cells with unprecedented precision and resolution. This technology has transformed the understanding of genetic mutations and is now extensively used to characterize genomes and facilitate the translation of findings into clinical research. “We are just recognizing that contrary to what we learned in textbooks, every cell in our body doesn't have the exact same DNA,” Sanders remarked.
Genetic Mosaicism in Healthy Individuals
This study is the first to utilize Strand-seq technology to investigate mutations in the DNA of healthy individuals. The researchers analyzed biological samples from a diverse age range, from newborns to 92-year-olds, discovering mutations in blood stem cells, located in the bone marrow, in 84% of participants. This indicates that large genetic mutations are highly prevalent.
“It’s just amazing how much heterogeneity there is in our genomes that has gone undetected so far,” Sanders noted. “What this means in terms of how we define normal human aging and how this can impact the types of diseases we get is really an important question for the field.”
The study also revealed that in individuals over 60, bone marrow cells with genetic alterations were more abundant, with specific genetic variants, or sub-clones, being more common. The frequent presence of these sub-clones suggests a potential link to aging.
However, whether mechanisms that restrain sub-clone proliferation deteriorate with age, or if the expansion of sub-clones directly contributes to aging-related diseases, remains uncertain. “In the future, our single-cell studies should give us clearer insights into how these mutations that previously went unnoticed affect our health and potentially contribute to how we age,” Korbel concluded.
EMBL and Max Delbrück Center Researchers Uncover Extensive Genetic Variability in Healthy Cells
In a study led by Jan Korbel from the European Molecular Biology Laboratory (EMBL) and Ashley Sanders from the Berlin Institute for Medical Systems Biology of the Max Delbrück Center (MDC-BIMSB), researchers have discovered that roughly one in 40 human bone marrow cells harbor substantial chromosomal alterations, such as copy number variations and chromosomal rearrangements. Remarkably, these alterations do not result in any observable disease or abnormality. Furthermore, cell samples from individuals over the age of 60 exhibited a higher incidence of cells with genomic alterations, suggesting a novel mechanism potentially contributing to aging-related diseases. These findings were recently published in Nature Genetics.
“The study highlights that we are all mosaics,” stated Korbel, Senior Scientist in the Genome Biology Unit and Head of Data Science at EMBL Heidelberg. “Even so-called normal cells carry all sorts of genetic mutations. Ultimately, this means that there are more genetic differences between individual cells in our bodies than between different human beings.”
Korbel and Sanders, Group Leader at the Max Delbrück Center, investigate how genetic structural variation, including deletions, duplications, inversions, and translocations of large genome sections, influence disease development. In oncology, it is well-documented that genetic mutations can cause cells to grow uncontrollably, leading to tumor formation. “We are applying similar concepts to understand how non-cancerous diseases develop,” Sanders explained.
Innovative Single-Cell Sequencing Technology: Strand-Seq
The discovery was made possible through a cutting-edge single-cell sequencing technology known as Strand-seq. This unique DNA sequencing technique unveils intricate genomic details in single cells that other methods fail to detect. Sanders played a pivotal role in the development of Strand-seq, refining the protocol during her doctoral research and postdoctoral fellowship in Korbel’s lab.
Strand-seq enables researchers to detect structural variants in individual cells with unprecedented precision and resolution. This technology has transformed the understanding of genetic mutations and is now extensively used to characterize genomes and facilitate the translation of findings into clinical research. “We are just recognizing that contrary to what we learned in textbooks, every cell in our body doesn't have the exact same DNA,” Sanders remarked.
Genetic Mosaicism in Healthy Individuals
This study is the first to utilize Strand-seq technology to investigate mutations in the DNA of healthy individuals. The researchers analyzed biological samples from a diverse age range, from newborns to 92-year-olds, discovering mutations in blood stem cells, located in the bone marrow, in 84% of participants. This indicates that large genetic mutations are highly prevalent.
“It’s just amazing how much heterogeneity there is in our genomes that has gone undetected so far,” Sanders noted. “What this means in terms of how we define normal human aging and how this can impact the types of diseases we get is really an important question for the field.”
The study also revealed that in individuals over 60, bone marrow cells with genetic alterations were more abundant, with specific genetic variants, or sub-clones, being more common. The frequent presence of these sub-clones suggests a potential link to aging.
However, whether mechanisms that restrain sub-clone proliferation deteriorate with age, or if the expansion of sub-clones directly contributes to aging-related diseases, remains uncertain. “In the future, our single-cell studies should give us clearer insights into how these mutations that previously went unnoticed affect our health and potentially contribute to how we age,” Korbel concluded.