Newly Identified DARG Cells May Hold the Key to Halting MS Progression

In progressive multiple sclerosis, a quiet fire smolders where the brain repairs itself least. A new study in Cambridge and at the National Institute on Aging traces that fire to an unusual glial state that appears primed for inflammation.

Working with patient skin cells reprogrammed into induced neural stem cells, the team mapped transcripts, chromatin, and DNA methylation in high resolution. They found a distinct subpopulation they call disease associated radial glia like cells, or DARGs, that carry an epigenetically dysregulated interferon response and hallmarks of cellular senescence. These cells were rare in controls but prominent in lines from people with progressive MS. In post mortem brain datasets, DARGs localized to the rims and edges of chronically active lesions, near activated microglia and inflamed astrocytes.

Radial glia like cells are developmental specialists in the healthy brain, scaffolding new circuits and differentiating as needed. Here, the authors report a shift into a non neurogenic, inflammatory state. Multi omics integration indicated hypomethylation at interferon pathway genes in patient fibroblasts that persisted after direct reprogramming, along with increased chromatin accessibility at interferon responsive promoters and enhancers. The signature converged on IRF1 and related transcription factors, consistent with a cell primed to sense RNA and DNA danger signals and broadcast distress.

“Our research has revealed a previously unappreciated cellular mechanism that appears central to the chronic inflammation and neurodegeneration driving the progressive phase of the disease.”

Functionally, conditioned media from progressive MS iNSCs pushed matched control cells toward senescence and interferon signaling, reducing proliferation and tilting networks away from maintenance pathways such as Notch and Wnt. A vivid pattern emerges in spatial data as well. Spots with high DARG scores were enriched at lesion rims and perilesional white matter, where oligodendrocyte proportions drop and foamy, iron loaded microglia accumulate. Picture the map: a pale arc at a lesion edge, glia thickening like storm clouds, with DARG signals peaking where damage creeps outward.

Epigenetic Memory Sets The Fuse

The most provocative thread is upstream of the brain. Progressive MS fibroblasts already carried hypomethylation at interferon and lipid metabolism genes. Direct reprogramming preserved epigenetic age, unlike iPSC routes that reset it, exposing disease relevant memory in the resulting neural stem cells. That memory appears to set the fuse for exaggerated interferon responses and a senescence leaning state once the cells encounter stress.

Gene regulatory network analyses centered on IRF family members and p53, and single cell regulon inference highlighted IRF1 and FOXP2 as DARG defining modules. The interferon tilt was not abstract. Interferon stimulated genes such as IFIT1 and ISG15 rose with matching promoter accessibility. Meanwhile, regulatory programs for differentiation and neural crest fates receded. The system looks biased toward alarm and away from repair.

Levers For Therapy And Tests That Matter

Therapeutically, the study offers levers. Treating progressive MS iNSCs with the senolytic ABT 263 did not abolish the inflammatory cluster, but it dampened interferon and senescence transcripts and blunted the toxic secretome. In systems terms, that is a senomorphic effect that reshapes outputs without removing the node. It suggests a path to lower smoldering inflammation even if DARGs persist.

Translation will hinge on robust markers and causality. The authors provide candidate signatures that can be tracked in tissue and potentially in biofluids once refined. They also show that DARGs co localize with lesion niches that are known to predict progression, an important link between cell state and patient relevant pathology. The next tests are clear: define surface targets, confirm functional roles in models that recapitulate lesion rims, and measure whether senomorphic or antiviral strategies slow the spread of chronic lesions.

Uncertainty remains. DARGs could originate from mature astrocytes that de differentiate under chronic stress, or from a precursor pool that fails to complete a neurogenic program. Viral history and endogenous retroviral activity may prime interferon responses and epigenetic drift. These hypotheses are now testable with the code and datasets made public, including bulk RNA seq, single cell RNA and ATAC, and spatial re analyses.

“Our goal is to develop therapies that either correct DARG dysfunction or eliminate them entirely.”

For people living with progressive MS, effective treatments have lagged the biology. This work isolates a candidate driver, roots it in epigenetic memory, and ties it to lesion geography that matters clinically. It swaps vague talk of smoldering inflammation for a concrete cellular program with knobs to turn and wires to cut.

Neuron: 10.1016/j.neuron.2025.09.022