In laboratories where scientists coax stem cells into becoming nerve cells, a long-standing assumption has been that the results look like the real thing. A team led from Skoltech, working with colleagues across Russia, has now measured how the DNA inside these cells is folded and found that they remain closer to the youthful cells they came from than to the mature neurons of an adult brain. The finding asks researchers to remember that a model carries its history with it, and that a cell's age can be written in the shape of its genome rather than in its appearance. For early development, this
Lab-Grown Neurons Keep Early-Development Chromatin Traits, Limiting Models for Late-Onset Brain Disease
For some questions differentiated neurons are suitable, for others they are not.
Mark
So what exactly did they find?
Mimi
That neurons made from induced pluripotent stem cells fold their DNA more like progenitor cells than like mature adult neurons.
Mark
What does that look like physically?
Mimi
Smaller, more densely packed structural domains, and much weaker long repressive contacts, which in adult neurons help silence genes.
Luke
Before we go further, what's the evidence base? Is this one lab's small sample?
Mimi
It's more than 300 genome maps across 62 human and 34 mouse samples, plus five new maps the authors made themselves.
Luke
Fair, but the conclusion that this limits disease modeling is the researchers' own interpretation. The study measured chromatin architecture; it didn't test a disease model directly, at least not in what we've been told.
Mark
So the leap to neurodegeneration is inferred?
Mimi
Khrameeva says the immaturity limits use for late-onset disease modeling. That's her reading of the structural findings.
Luke
And we don't know from this reporting whether any particular published disease model is invalidated.
Mark
Is it all bad news for these cells, then?
Mimi
No. The same early-stage traits make them useful for studying development, and the open database helps researchers choose the right model for their question.
O Pulso
- Lab-grown neurons, prized for mirroring a patient's own genetics, turn out to carry the fingerprints of early development in how their DNA is folded.
- Long repressive DNA contacts that quiet genes in mature adult neurons are far weaker in these cultured cells, leaving key genes less controlled.
- Researchers compared more than 300 three-dimensional genome maps from human and mouse samples to reach the conclusion, a scale that unsettles earlier confidence in these models.
- The team is moving toward a practical rule of thumb: choose the model by the question, using these neurons for early brain development but treating them cautiously for neurodegeneration.
- The newly released database gives the field a shared reference, and the work is likely to reshape how labs justify their choice of cellular models.
In laboratories where scientists coax stem cells into becoming nerve cells, a long-standing assumption has been that the results look like the real thing. A team led from Skoltech, working with colleagues across Russia, has now measured how the DNA inside these cells is folded and found that they remain closer to the youthful cells they came from than to the mature neurons of an adult brain. The finding asks researchers to remember that a model carries its history with it, and that a cell's age can be written in the shape of its genome rather than in its appearance. For early development, this immaturity is a usable quality; for diseases that arrive late in life, it is a gap to be honestly accounted for.
For years, scientists growing neurons from stem cells have worked around an uncomfortable question: how grown-up are these cells, really? A team led by researchers at Skoltech, with colleagues from the Kharkevich Institute, Lomonosov Moscow State University, and other organizations, has now answered it in the language of genome structure. Their study, published in Genome Research, finds that the lab-grown cells are younger than hoped.
The stem cells in question begin as ordinary adult cells that are reprogrammed back toward an embryonic-like state. From them come neurons that carry the donor's own genetics, which is precisely what makes them valuable for studying nervous system diseases. But the researchers wanted to know how closely those neurons match the folded architecture of DNA in mature adult brain cells. To find out, they gathered and processed more than 300 three-dimensional genome maps, drawn from human and mouse samples, and added five maps of their own.
The pattern that emerged was consistent. The lab neurons resemble progenitor cells more than mature neurons. Their domains are smaller and more tightly packed, and the long repressive contacts that normally silence genes in adult neurons are much weaker. Khrameeva, the scientific supervisor, described the cells as keeping features typical of early development, which limits their use for late-onset conditions such as neurodegeneration. The same quality, she noted, makes them well suited to studying how the nervous system forms.
First author Diana Zagirova emphasized the database the team has made available to the research community, which allowed a systematic comparison against both postmortem neurons and progenitor cells. At every level they examined, the differentiated neurons differed from mature ones. The practical outcome, in her view, is a set of criteria for choosing models by task. Those studying early brain development now have a defensible tool, while those investigating diseases of later life will need to weigh what these cells lack.
A team led by scientists at Skoltech has put numbers on a question that stem-cell researchers have long worked around: how grown-up are neurons made in a dish? Their answer, published in the journal Genome Research, is that they are younger than hoped, at least in the way their DNA is folded inside the nucleus.
The work was done with colleagues from the Kharkevich Institute for Information Transmission Problems of the Russian Academy of Sciences, Lomonosov Moscow State University, and other organizations. It compared the three-dimensional organization of the genome in neurons derived from induced pluripotent stem cells with that of neurons from the adult human brain.
Induced pluripotent stem cells start as adult somatic cells and are genetically reprogrammed into a state resembling the embryonic one. From them, researchers can derive neurons that are genetically identical to the donor, which makes it possible to study nervous system diseases under laboratory conditions. What had remained unclear, according to the authors, was how closely those neurons reproduce the chromatin architecture of mature adult brain neurons.
To find out, the team collected and processed more than 300 3D genome maps. They cover 62 human samples and 34 mouse samples, and include embryonic stem cells, induced pluripotent stem cells, neural progenitors, fetal and postmortem neurons, and neurons differentiated in vitro. The authors also contribute five new 3D genome maps of their own.
The comparison showed that neurons differentiated from induced pluripotent stem cells sit closer to neuronal progenitor cells than to mature neurons. Active and inactive regions of the genome are separated more distinctly in them. The boundaries of structural domains, the regions where DNA interacts with itself, contain genes associated with development. Long repressive contacts, which in mature neurons suppress gene expression, are much less pronounced. The structural domains are smaller and more densely packed, a pattern characteristic of progenitor cells, and frequently interacting regulatory regions that normally control gene expression show reduced activity.
Ekaterina Khrameeva, the scientific supervisor and an associate professor at Skoltech's Biomed Technologies Center, said the lab-grown neurons do not reach the mature chromatin architecture of the adult brain. They keep features typical of early development, which she said limits their use for modeling late-onset conditions such as neurodegenerative diseases. The same immaturity, she added, makes them suitable for studying how the nervous system develops and which regulatory mechanisms matter at early stages.
Diana Zagirova, the first author, a junior research scientist at the center and an alumna of Skoltech's MSc program in Life Sciences, pointed to the database the team built. The 3D genome maps of human and mouse neuronal cells are available to the research community. She said it allowed the first systematic comparison of differentiated neurons against both postmortem neurons and progenitor cells, and that at every level examined the differentiated neurons differed from mature ones and kept a progenitor profile.
The practical upshot, in Zagirova's words, is a set of criteria for choosing a model by task: for some questions differentiated neurons are suitable, for others they are not. Researchers modeling early brain development have a defensible tool; those studying diseases of late life will need to weigh what these cells lack.
Citações Notáveis
Neurons grown from induced pluripotent stem cells do not reach the mature chromatin architecture of the adult brain, which limits their use for modeling late-onset diseases such as neurodegenerative ones.— Ekaterina Khrameeva, Skoltech
At each level, differentiated neurons differ from mature ones and retain the profile of progenitor cells.— Diana Zagirova, Skoltech
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