They also performed better in tests of motor function, gait coordination, grip strength and endurance. The findings describe experimental effects in mice and do not demonstrate that NMN can treat spinal cord injury in people. Spinal cord injury can produce localized damage that extends to neighboring cells and tissues over hours, days or weeks, adding to the severity of the initial injury.

Intracellular NAD+ levels decline rapidly during this progression. NAD+ is a coenzyme involved in energy metabolism and other physiological processes, including tissue repair, so depletion of the molecule can adversely affect cells and amplify tissue damage. NMN is a direct precursor of NAD+.

The researchers tested whether increasing NAD+ after spinal cord injury could preserve tissue, restrain the post-injury inflammatory response and support motor recovery. The treatment regimen was 500 mg of NMN per kilogram of body weight, administered by intraperitoneal injection immediately after a moderate contusion-type spinal cord injury and then daily for seven days. Investigators examined spinal cord sections with paraffin hematoxylin-eosin staining to measure vacuole area and with immunofluorescence to assess neuron counts and fluorescence intensity.

The treated animals showed reduced vacuole area and increased neuron counts, indicating less visible tissue disruption under the experimental conditions. The study combined these structural measurements with behavioral assessments rather than examining biochemical changes alone. Motor outcomes were evaluated with the Basso Motor Scale, gait coordination analysis, grip strength assessment and a baton-transfer endurance test.

Mice treated with NMN performed better across these measures after the injury. The convergence between the tissue and behavioral results indicates that the histological protection observed in treated mice was accompanied by improved locomotor performance. Molecular measurements provided a possible explanation for the observed neuroprotection.

Transcriptome sequencing, quantitative reverse-transcription polymerase chain reaction, protein microarray analysis and enzyme-linked immunosorbent assays collectively suggested that NMN attenuated inflammatory responses after injury. Western blot analysis indicated that this effect may have been mediated through the NF-κB pathway. The proposed mechanism is that increasing NAD+ with NMN helps protect injured spinal cord tissue, limits neuroinflammation and thereby supports locomotor recovery.

The researchers described the pathway relationship as a possible mechanism in the mouse model, rather than a demonstrated clinical effect. Overall, the study provides preclinical evidence for NMN as an intervention that may reduce tissue injury and improve motor outcomes following spinal cord injury, while the scope of the reported experiment remains limited to mice tested with a specific dose, route and seven-day schedule.

Subject of Research: Preclinical testing of nicotinamide mononucleotide for spinal cord injury in mice

Article Title: Nicotinamide mononucleotide elevates NAD+ to protect spinal cord tissue from injury and reduces inflammatory response to promote motor recovery

Article References: Zhang, C., Li, Y., Yu, Y., Bai, F., Jing, Y., Talifu, Z., Wang, X., Zhang, X., Li, J., & Cui, G. (2026). Nicotinamide mononucleotide elevates NAD+ to protect spinal cord tissue from injury and reduces inflammatory response to promote motor recovery. BMC Neuroscience. https://doi.org/10.1186/s12868-026-01063-w

Image Credits: AI Generated

DOI: 10.1186/s12868-026-01063-w

Keywords: nicotinamide mononucleotide, NAD+, spinal cord injury, motor recovery, neuroprotection, neuroinflammation, NF-κB pathway, mouse model, contusion injury, tissue damage, Nicotinamide, mononucleotide

The research team, led by Anne Caroline Rodrigues dos Santos Cavalcante and Suelen Adriani Marques, set out to answer a question that has lingered beneath years of encouraging rehabilitation data: when treadmill training improves locomotor recovery after spinal cord injury, what is actually happening inside the tissue? Previous work from the same group had shown that adjusting exercise volume according to the stage of injury maximises functional recovery, but the cellular and molecular mechanisms behind those behavioural gains remained largely opaque. To probe them, the researchers turned to a compressive injury model in fifty-two adult female mice, applying a 30-gram vascular clip to the spinal cord at the ninth thoracic vertebra for just ten seconds—a method that produces a reproducible, clinically relevant lesion while sparing the dura mater.

The rehabilitation protocol itself was deliberately conservative. Training began seven days after injury, during the subacute phase, and continued until fifty-six days post-injury. From day seven to day twenty-eight, animals completed two ten-minute treadmill sessions per training day, separated by a ten-minute rest interval; after day twenty-eight, this was reduced to a single ten-minute session. Sessions were held only three times per week, a frequency chosen to mirror what is actually feasible in clinical rehabilitation rather than to maximise exercise volume. The speeds ranged from six to twelve metres per minute, individually adjusted according to each animal’s locomotor performance and tolerance. This phase-adjusted design reflected the team’s earlier finding that exercise dosage must be tailored to the temporal evolution of the injury rather than simply intensified.

The behavioural results were striking. Untreated injured mice remained trapped in the earliest stage of locomotor recovery throughout the entire fifty-six-day follow-up, scoring just 1.48 on the Basso Mouse Scale by the end of the study. Treadmill-trained animals, by contrast, reached 4.02—a statistically significant difference that emerged from twenty-one days post-injury onward and persisted until the end of the experiment. On the Ladder Walking Test, which challenges animals to cross a horizontal ladder with irregularly spaced rungs, trained mice took significantly more total steps from thirty-five days post-injury and, more importantly, placed their paws significantly more accurately from forty-two days onward, indicating improved fine motor coordination rather than simply gross movement.

Sensory function also benefited. Using an electronic von Frey anesthesiometer, the researchers measured the pressure required to trigger a paw withdrawal reflex. Untreated injured animals showed markedly elevated thresholds—2.20 grams on the right paw and 2.01 on the left—reflecting profound sensory loss. Trained animals averaged 1.10 and 1.15 grams respectively, significantly closer to the uninjured baseline of roughly 0.61 grams. This partial preservation of sensory processing suggests that the rehabilitation protocol protected ascending pathways as well as descending motor tracts, a finding consistent with the broader tissue preservation documented throughout the study.

Electrophysiological recordings provided objective confirmation that neural conduction itself was preserved. At fifty-six days post-injury, the researchers exposed the cervical spinal cord and delivered supramaximal electrical stimuli while recording compound muscle action potentials from the gastrocnemius muscle. Untreated injured animals showed a dramatic reduction in signal amplitude—0.59 compared with 1.55 in uninjured controls—along with prolonged latency. Trained animals recorded amplitudes of 1.18, statistically indistinguishable from the uninjured group. Although such recordings do not directly demonstrate axonal regeneration, they provide compelling functional evidence that the descending motor pathways remained conductive in exercised animals, complementing the behavioural and morphological findings.

The molecular heart of the study lies in its analysis of the inflammatory microenvironment. Using ELISA assays on spinal cord tissue cultured for twenty-four hours, the team quantified six cytokines. Untreated injured animals exhibited a clear pro-inflammatory profile, with elevated levels of tumour necrosis factor-alpha, interleukin-1 beta and interleukin-6. Trained animals showed the opposite pattern: reduced pro-inflammatory cytokines alongside increased levels of the anti-inflammatory mediators interleukin-10, interleukin-13 and transforming growth factor-beta. This shift matters because sustained production of inflammatory cytokines after spinal cord injury drives microglial activation, immune cell infiltration, demyelination and neuronal apoptosis. During moderate exercise, skeletal muscle releases interleukin-6 as a myokine, which in turn promotes anti-inflammatory signalling and suppresses tumour necrosis factor-alpha production—a mechanism the authors cite as particularly relevant to their findings.

Immunofluorescence labelling revealed how this cytokine shift translated into changes in glial cell behaviour. The researchers used TMEM119 to mark the general microglial population, arginase-1 to identify anti-inflammatory M2-like microglia, and inducible nitric oxide synthase to flag pro-inflammatory M1-like cells. In trained animals, Pearson’s correlation between TMEM119 and arginase-1 reached 0.85, indicating that the majority of resident microglia had adopted an anti-inflammatory phenotype. In untreated injured animals, this correlation fell to 0.46, while the correlation between TMEM119 and the pro-inflammatory marker iNOS climbed to 0.836—compared with just 0.33 in trained mice. The team also documented reduced GFAP immunoreactivity in trained animals, suggesting attenuated reactive astrogliosis and a less restrictive glial scar, alongside significantly lower expression of cleaved caspase-3, a hallmark of apoptotic cell death.

Structural preservation followed the molecular changes. Transmission electron microscopy of semithin cross-sections at the lesion epicentre revealed that trained animals retained 1,658 myelinated nerve fibres on average, compared with just 200 in untreated injured animals. The g-ratio—the relationship between inner axonal diameter and total fibre diameter—shifted toward the optimal range of 0.6 to 0.7 in trained mice, indicating more efficient myelination. Micro-computed tomography confirmed that the lesion area was significantly smaller in trained animals (0.243 square millimetres versus 0.382), and scanning electron microscopy showed better organisation of both grey and white matter, with smaller cavitations at the injury site.

The benefits extended beyond the spinal cord itself. Trained animals preserved significantly more muscle mass in both the soleus and gastrocnemius, retained more neuromuscular junctions with their characteristic pretzel morphology, and maintained bladder wall thickness close to normal levels. Untreated injured animals developed dramatic bladder muscular hypertrophy—574.963 micrometres compared with 127.857 in controls—accompanied by inflammatory remodelling. The authors note that these autonomic complications are major contributors to urinary tract infections and repeated hospitalisation after human spinal cord injury. While the study used only female mice, a deliberate choice to reduce behavioural variability and avoid genital injury during recovery, the authors acknowledge that future work must include both sexes to confirm broader applicability. Taken together, the findings reframe treadmill rehabilitation not simply as locomotor training but as a coordinated biological therapy—one that appropriately dosed exercise can deploy to shift the injured spinal cord from a hostile inflammatory state toward one permissive for tissue repair and neural conduction.

Subject of Research: Neuroscience

Article Title: Treadmill Exercise Can Modulate the Inflammatory Microenvironment and Promote Regeneration After Compressive Spinal Cord Injury in Female Mice

Article References: Cavalcante, A. C. R. D. S., Laurindo, R. P., Heringer, L. D. S., Toledo, A. L. M. M., Souza, G. S., da Silva, G. F. Q., dos Santos, A. C. C., Branco, M. T. L. C., Martinez, A. M. B., & Marques, S. A. (2026). Treadmill Exercise Can Modulate the Inflammatory Microenvironment and Promote Regeneration After Compressive Spinal Cord Injury in Female Mice. Journal of Cellular and Molecular Medicine, 30(20), Article e71351. https://doi.org/10.1111/jcmm.71351

Image Credits: AI Generated

DOI: 10.1111/jcmm.71351

Keywords: spinal cord injury, treadmill exercise, neuroinflammation, microglia, rehabilitation, neuroregeneration, Treadmill, Exercise, Modulate, Inflammatory, Microenvironment, Promote

The study, published in Frontiers in Molecular Neuroscience, grew out of an earlier investigation in which the researchers used small RNA sequencing to profile the blood of patients with advanced gastric cancer receiving XELOX chemotherapy, a widely used combination of capecitabine and oxaliplatin. Oxaliplatin is notorious for its neurotoxicity, and the team had previously identified five microRNAs whose circulating levels changed with chemotherapy exposure. When the researchers validated those candidates using quantitative PCR, only one of them, miR-378f, showed a statistically significant correlation with the severity of peripheral neuropathy. That single hit became the thread the team followed into the molecular machinery of nerve repair.

MicroRNAs are short non-coding RNAs, typically 21 to 23 nucleotides long, that fine-tune gene expression after a gene has been transcribed. They bind to complementary sequences in messenger RNA molecules, either blocking translation into protein or tagging the mRNA for degradation. Because a single microRNA can regulate dozens or even hundreds of targets, these molecules sit at critical control points in cellular networks, and their dysregulation has been implicated in cancer, neurological disorders and inflammation. In the context of nerve injury, microRNAs have been shown to modulate oxidative stress, neuroinflammation, axonal growth and autophagy, making them attractive both as biomarkers and as potential therapeutic levers.

To find what miR-378f might be controlling, the team turned to bioinformatic prediction tools. Using the miRNet platform, which integrates experimentally validated target data from TarBase and miRTarBase, they mapped the targets of all five chemotherapy-associated microRNAs. Among the predicted targets, calcium-binding protein 39, or CAB39, stood out: it was targeted by three of the five candidates, including miR-378f itself. CAB39 was already known to the researchers as an activator of AMPK, a cellular energy sensor that, when switched on, suppresses the growth-promoting kinase mTOR and thereby triggers autophagy. The stage was set for a hypothesis: when miR-378f levels fall, CAB39 rises, and the autophagy program in nerve cells is unleashed.

Autophagy, literally self-eating, is a genetically controlled process in which cells build double-membraned vesicles called autophagosomes that engulf damaged proteins, dysfunctional organelles and other cytoplasmic debris, delivering them to lysosomes for destruction and recycling. Far from being a destructive act, autophagy is fundamentally protective: it supplies nutrients under stress and clears out the molecular wreckage that accumulates after injury. In the peripheral nervous system, where nerves retain a remarkable capacity for regeneration, autophagy has been shown to facilitate the clearance of myelin debris, support axonal repair and promote functional recovery after injury. Inhibiting mTOR to activate autophagy has even been shown to provide neuroprotection in the early stages of nerve damage.

The experimental work was carried out in SH-SY5Y cells, a human neuroblastoma-derived cell line widely used as a neuronal model. The researchers transfected the cells with synthetic miR-378f mimics to overexpress the microRNA and with inhibitors to suppress it, optimizing dose and timing before measuring outcomes. The morphological results were striking: blocking miR-378f significantly extended the length of neurites, the slender projections that neurons use to connect and communicate, while overexpressing the microRNA shortened them. Branching followed a similar pattern. In short, less miR-378f meant more nerve growth, a result consistent with the idea that the microRNA acts as a brake on regenerative programs.

To confirm that CAB39 was a direct target rather than an indirect consequence, the team performed dual-luciferase reporter assays. They cloned the wild-type 3-prime untranslated region of CAB39, the segment where microRNAs typically bind, into a reporter plasmid, alongside a mutant version with the predicted binding site disrupted. Co-transfecting the wild-type construct with the miR-378f mimic reduced luciferase activity, while the inhibitor increased it, but neither manipulation affected the mutant construct. That clean pattern is the molecular equivalent of a smoking gun: miR-378f binds directly to the CAB39 transcript and represses it.

Western blotting then traced the signaling cascade downstream. When miR-378f was inhibited, CAB39 protein levels rose, phosphorylated AMPK increased and phosphorylated mTOR decreased, while total AMPK and mTOR remained unchanged, indicating that the microRNA was altering the activation state of the pathway rather than the abundance of its components. The autophagy markers shifted in the expected direction: Beclin-1, an initiator of autophagosome formation, went up; the ratio of lipidated LC3-II to LC3-I, a hallmark of autophagosome biogenesis, increased; and p62, a cargo receptor that accumulates when autophagic degradation stalls, went down. Overexpressing miR-378f produced the mirror-image pattern. Together, the data show that suppressing miR-378f activates the molecular signature of autophagy through the CAB39-AMPK-mTOR axis.

The clinical validation, though modest in scale, aligned with the cell culture results. The researchers analyzed blood samples from ten gastric cancer patients treated at Pusan National University Hospital, divided into those who had received fewer than four cycles of XELOX and those who had received four to six. Patients with greater cumulative exposure and more severe neuropathy, graded by oncologists using the National Cancer Institute’s Common Terminology Criteria for Adverse Events, showed significantly lower miR-378f levels alongside elevated CAB39, Beclin-1 and LC3-II transcripts. The authors interpret this as evidence that autophagy is enhanced as neuropathy worsens, likely reflecting a compensatory repair response rather than a cause of the damage itself.

The researchers are careful about the limits of their work. Autophagic flux and autophagosome formation were not directly measured, the neuronal cells were never exposed to chemotherapy drugs, and no animal experiments were performed. SH-SY5Y cells, moreover, do not fully replicate primary peripheral sensory neurons, and the clinical cohort lacked a chemotherapy-exposed control group without neuropathy. Still, the study sketches a coherent and testable pathway: chemotherapy injures peripheral nerves, miR-378f falls as part of a counter-regulatory response, CAB39 is derepressed, AMPK is activated, mTOR is inhibited, and the autophagy machinery mobilizes to clear damage and support regeneration. If future work in primary neurons, animal models and larger patient cohorts confirms the mechanism, miR-378f could serve double duty as a biomarker for identifying patients at risk of severe neuropathy and as a therapeutic target whose manipulation might one day help protect the nerves that cancer treatment so often sacrifices.

Subject of Research: The role of miR-378f and CAB39 in regulating autophagy in chemotherapy-induced peripheral neuropathy

Article Title: miR-378f targets CAB39 to regulate autophagy in chemotherapy-induced peripheral neuropathy

Article References: Kim, Y., Jeong, M., Kwon, H., Kim, J., Ju, Y., Kang, D.-Y., Jang, A., & Choi, G.-E. (2026). miR-378f targets CAB39 to regulate autophagy in chemotherapy-induced peripheral neuropathy. Frontiers in Molecular Neuroscience, 19, Article 1958322. https://doi.org/10.3389/fnmol.2026.1958322

Image Credits: AI Generated

DOI: 10.3389/fnmol.2026.1958322

Keywords: miR-378f, CAB39, autophagy, chemotherapy-induced peripheral neuropathy, microRNA, AMPK, mTOR, oxaliplatin, neuroregeneration, Beclin-1, LC3, gastric cancer

The research team, led by Anyi Zhang, Luca Masin, and Lieve Moons of KU Leuven together with collaborators in Paris, used a transgenic zebrafish line that sparsely labels individual retinal ganglion cells with a fluorescent membrane marker, making it possible to trace the full dendritic tree of single neurons in the adult retina. By combining this imaging approach with optic nerve crush injury, quantitative morphometrics, transcriptomic analysis, and pharmacological manipulation, they mapped how dendritic architecture changes as axons regenerate, and identified the molecular switch that governs the process.

The first surprise came from the anatomy. After optic nerve crush, the dendrites of retinal ganglion cells did not remain intact while their axons regrew. Instead, by three days post-injury the cells had lost roughly thirty percent of their total dendritic length and branch points, and by six days, when axons were just beginning to re-enter the brain, the number of bifurcations had fallen to around sixty percent of uninjured levels. Crucially, the overall footprint of the dendritic field was largely preserved, indicating that the remodeling involved the selective elimination of terminal branches rather than wholesale collapse of the arbor. As the axons re-established connections with the optic tectum, the brain’s visual processing center, dendritic complexity rebounded, approaching uninjured architecture by twenty-one days after injury.

This transient simplification was not random degeneration. Gene set enrichment analysis of a bulk RNA sequencing dataset from isolated adult zebrafish retinal ganglion cells showed that transcripts associated with synapses, dendrites, and synaptic transmission were coordinately downregulated between one and six days post-injury, precisely the window in which axons are extending through the optic nerve. The same window saw a sweeping suppression of the insulin-PI3K-Akt-mTOR cascade, the signaling pathway long regarded as a master regulator of cellular growth and a major target of regenerative medicine. Receptor and adapter components such as insra, irs1, and irs2a declined, as did regulatory PI3K subunits and key nodes of the mTOR machinery including rptor, rictor, rheb, and tsc genes.

Because RNA levels are an imperfect proxy for pathway activity, the researchers also examined protein phosphorylation in retinal tissue. They used antibodies against phosphorylated ribosomal protein S6, a well-established readout of mTORC1 activity, the growth-controlling complex downstream of Akt. The results revealed a striking biphasic pattern. In the first two days after injury, the fraction of S6-phosphorylated cells in the ganglion cell layer surged, reaching roughly fifty percent for the Ser235/236 site and up to eighty-five percent for the Ser240/244 site, suggesting an early burst of mTORC1 activity that likely helps initiate the regenerative program. Then, from day three onward, the signal collapsed to near-undetectable levels, coinciding exactly with the onset of dendritic pruning and sustained axonal elongation.

The team also tested whether Gsk3β, a kinase previously implicated in dendrite pruning, was driving the remodeling. Although total Gsk3β protein increased after injury, its inhibitory Ser9 phosphorylation rose even more, indicating a net reduction in kinase activity. The pruning program, in other words, was associated primarily with the repression of mTORC1 signaling rather than with activation of the destructive kinase, sharpening the causal picture.

The decisive experiment came from pharmacology. When the researchers injected recombinant human insulin into the eye on days two through four after injury, they kept the mTOR pathway active during the window when it would normally be suppressed. Insulin treatment did exactly what the model predicted: it partially preserved dendritic complexity, with treated retinal ganglion cells retaining greater dendritic length, area, and branching at six days post-injury. But the preserved dendrites came at a cost. Anterograde tracing with biocytin showed that insulin-treated fish reinnervated their optic tectum roughly fifty percent less than vehicle-treated controls, a clear delay in axonal regrowth. Keeping the dendrites intact, it seemed, actively hindered the rebuilding of the axon.

Follow-up experiments confirmed that this effect runs through mTORC1. Rapamycin, a selective mTORC1 inhibitor, reversed the dendritic preservation caused by insulin, restoring dendritic metrics to vehicle levels. Conversely, MHY1485, a small-molecule mTOR activator, mimicked insulin: it increased dendritic complexity, including more than a fifty percent rise in branch points, and likewise delayed tectal reinnervation by about half. Together, these results establish that mTORC1-dependent maintenance of dendritic branching is a limiting factor for sustained axonal regrowth in the regenerating zebrafish visual system.

Why would a neuron sacrifice its input structures to rebuild its output? The authors propose a resource-allocation model. In mature mammalian neurons, mitochondria become locked near synapses and recycling endosomes are confined to the somatodendritic compartment, whereas regenerating zebrafish retinal ganglion cells transiently relocate mitochondria from dendrites into elongating axons. Insulin receptors sit at the postsynaptic density and mTOR is enriched in dendrites, where it drives local protein synthesis. By pruning dendrites and repressing dendritic mTOR signaling, the neuron may free up protein synthesis capacity, membrane material, and metabolic energy, redirecting these limited resources toward the growing axon. The sequence also echoes development: in both fish and mice, retinal ganglion cells extend their axons first and only elaborate dendrites after the axon has reached its brain target, suggesting that the adult regenerative program recapitulates an ancient developmental order to avoid competition between the two compartments.

The findings carry an uncomfortable implication for mammalian regenerative medicine. Strategies that hyperactivate mTOR, such as PTEN deletion, reliably induce robust axonal regrowth in injured mouse optic nerves, yet extensive functional reinnervation of central brain targets remains largely unachieved. The zebrafish data raise the possibility that sustained mTOR activity may itself hinder the later phases of repair, and that precisely timed, biphasic control of the pathway, an early burst to initiate regeneration followed by deliberate suppression to permit dendritic remodeling and resource reallocation, could be the missing ingredient. Translating that temporal logic to the mammalian central nervous system will be challenging, and the authors caution that their study relied on pharmacological tools rather than genetic perturbation, did not examine contributions from microglia or Müller glia, and leaves open how dendritic pruning affects the electrical activity of regenerating neurons. Still, the message from the fish is clear and provocative: sometimes the best way to rebuild a nerve is to let part of the cell go first.

Subject of Research: Dendritic pruning and mTORC1 signaling regulation during optic nerve regeneration in adult zebrafish retinal ganglion cells

Article Title: Repressed mTORC1 signaling and transient dendritic pruning support axonal regeneration in adult zebrafish

Article References: Zhang, A., Masin, L., Bergmans, S., Putti, E., Albadri, S., Poulain, F. E., Del Bene, F., & Moons, L. (2026). Repressed mTORC1 signaling and transient dendritic pruning support axonal regeneration in adult zebrafish. iScience, 29(11), Article 117826. https://doi.org/10.1016/j.isci.2026.117826

Image Credits: AI Generated

DOI: 10.1016/j.isci.2026.117826

Keywords: zebrafish, optic nerve regeneration, retinal ganglion cells, dendritic pruning, mTORC1, insulin signaling, axonal regrowth, optic tectum reinnervation, neuroregeneration, PI3K-Akt-mTOR, rapamycin, CNS repair

Astrocytes are the most abundant glial cells in the central nervous system, and in the healthy brain they perform a long list of housekeeping duties. They regulate the chemical environment around synapses, supply metabolic support to neurons, recycle neurotransmitters, and help maintain the blood-brain barrier. When injury, stroke, or neurodegenerative disease strikes, however, astrocytes undergo a dramatic transformation. They hypertrophy, proliferate, and secrete extracellular matrix molecules, forming a dense glial scar. This scar has a dual character. On one hand, it limits inflammation and seals off damaged tissue, preventing the injury from spreading. On the other, it secretes chemical signals that suppress axon regrowth and stands in place of the neurons that were lost. For decades, researchers have debated whether the scar is a friend or an enemy of recovery, and a growing body of work has explored whether the cells inside it could be redirected toward a more useful fate.

The idea of converting glial cells into neurons is not new. Direct lineage reprogramming, or transdifferentiation, forces a differentiated cell to switch identities without passing through an embryonic stem-cell-like state. Earlier studies showed that transcription factors such as NeuroD1, Ascl1, and Ngn2 could push astrocytes, and in some cases reactive astrocytes specifically, toward neuronal fates. In vivo conversion experiments, in which the reprogramming factors were delivered directly into injured brains or spinal cords, generated considerable excitement because they suggested a way to regenerate neurons at the site of damage without transplanting cells. Yet the field has also faced skepticism. Some follow-up studies questioned whether the converted cells were truly derived from astrocytes rather than from a small reservoir of neuronal progenitors, and others found that the induced neurons did not always mature into fully functional circuit elements. Building a method that is both efficient at targeting scar-forming astrocytes and reliable at producing working neurons has remained a significant challenge.

TRANsCre-DIONE, as described in the new report, is designed to meet that challenge head-on. The technique combines genetic targeting elements that drive reprogramming specifically in reactive astrocytes with a factor system that pushes the targeted cells toward a motor neuron identity. The reactive astrocyte specificity matters for two reasons. First, it concentrates the reprogramming machinery where it is needed most, in the scar tissue that accumulates after injury. Second, it minimizes off-target conversion of other cell types, including resting astrocytes that are still performing their normal supportive functions and oligodendrocyte lineage cells that maintain the myelin sheaths around axons. Precision of this kind is a recurring concern in gene therapy approaches to the nervous system, where delivery vehicles cannot always discriminate between neighboring cell populations.

According to the study, the converted cells do not merely adopt a superficial neuronal appearance. The authors report that TRANsCre-DIONE-derived cells acquire molecular signatures characteristic of motor neurons, including expression of marker genes associated with that lineage, and display electrophysiological properties consistent with functional neurons, such as the ability to fire action potentials and form synaptic connections. Functional maturation is the gold standard in the reprogramming field because many induced neurons stall at an immature state, resembling embryonic neurons rather than the specialized adult cell types needed to restore lost functions. Motor neurons in particular carry a heavy burden: they are the final common pathway through which the brain and spinal cord command muscles to contract, and their loss underlies devastating conditions ranging from spinal cord injury to amyotrophic lateral sclerosis.

The implications for motor neuron diseases and spinal cord injury are among the most compelling aspects of the work. In amyotrophic lateral sclerosis, the progressive degeneration of motor neurons leaves scar-forming glia in their wake, and any therapy that could recruit those resident glial cells to replace lost neurons would in principle address both the cell loss and the inhibitory environment at the same time. Similarly, after traumatic spinal cord injury, the lesion core becomes dominated by reactive astrocytes, and converting even a fraction of them into neurons capable of relaying motor commands could help bridge the gap that currently prevents functional recovery. The study’s demonstration that scar-forming cells, rather than a separate progenitor population, can be redirected toward a motor neuron fate speaks directly to this therapeutic vision.

At the same time, the authors and the broader field are careful to note the distance between a laboratory demonstration and a clinical therapy. Delivering reprogramming factors to cells inside the human central nervous system remains a formidable engineering problem. Viral vectors, the most common delivery vehicles, have limited cargo capacity and raise safety questions, particularly when the factors being delivered are transcription factors with the potential to alter cell identity in unintended ways. Researchers must also show that converted neurons integrate appropriately into existing circuits, receive the right inputs, and project to the correct targets, all without provoking immune responses or tumor-like overgrowth. Long-term studies will be needed to confirm that TRANsCre-DIONE-derived motor neurons survive, maintain their identity, and remain functional over the months and years that a real therapy would require.

There are also scientific questions that the new work will likely stimulate. How closely do the induced motor neurons match their endogenous counterparts at the level of gene expression, chromatin state, and connectivity? Do the converted cells retain any memory of their astrocyte origin that might affect their long-term behavior? And can the approach be tuned so that the timing and extent of conversion can be controlled in a living organism, allowing clinicians to modulate the treatment as recovery proceeds? Answers to these questions will determine whether TRANsCre-DIONE becomes a platform technology adaptable to multiple contexts of nervous system damage, or a specialized tool for specific experimental settings. The study adds to a growing consensus, however, that the cells of the glial scar should be viewed not only as obstacles to recovery but also as a locally abundant source of raw material for repair.

What makes the report resonant beyond its immediate technical contribution is the broader shift in perspective it represents. For most of the history of neuroscience, adult central nervous system neurons were considered irreplaceable, and glial scarring was treated as an irreversible endpoint of injury. Over the past decade, that pessimism has given way to a more dynamic view of the injured nervous system, one in which resident cells retain latent developmental programs that can, under the right molecular instructions, be reawakened. TRANsCre-DIONE contributes to this shift by showing that the very cells that barricade a lesion can be instructed to become the neurons needed to restore function. As the team and other groups refine the efficiency, safety, and controllability of such conversions, the prospect of rebuilding neural circuits from within the scar tissue itself moves from science fiction closer to experimental reality, offering a measure of hope to patients whose conditions have long been considered untreatable.

Subject of Research: Direct conversion of scar-forming reactive astrocytes into functional motor neurons using the TRANsCre-DIONE transdifferentiation approach

Article Title: TRANsCre-DIONE transdifferentiates scar-forming reactive astrocytes into functional motor neurons

Article References: An, H., Lee, H.-L., Cho, D.-W., Hong, J., Lee, H. Y., Lee, J. M., Choi, S., Hwang, I.-Y., Woo, J., Lee, J., Park, M., Yang, Y.-S., Han, S.-C., Ha, Y., & Lee, C. J. (2026). TRANsCre-DIONE transdifferentiates scar-forming reactive astrocytes into functional motor neurons. Experimental & Molecular Medicine. https://doi.org/10.1038/s12276-026-01815-y

Image Credits: AI Generated

DOI: 10.1038/s12276-026-01815-y

Keywords: reactive astrocytes, motor neurons, transdifferentiation, neuroregeneration, glial scarring, gene therapy, cell fate conversion, neuroscience, spinal cord injury, neurodegenerative disease, cellular reprogramming, Experimental and Molecular Medicine