Central Nervous System Repair Research Articles

Next generation drug connectivity mapping for acquiring therapeutic agents to differentially regulate myelination.

Next generation drug connectivity mapping for acquiring therapeutic agents to differentially regulate myelination.

Neuregulin-1 reverses anxiety-like behavior and social behavior deficits induced by unilateral micro-injection of CoCl2 into the ventral hippocampus (vHPC)

Neuregulin-1 (NRG1) is an epidermal growth factor family member with essential roles in the developing and adult nervous systems. In recent years, establishing evidence has collectively suggested that NRG1 is a new modulator of central nervous system (CNS) injury and disease, with multifaceted roles in neuroprotection, remyelination, neuroinflammation, and other repair mechanisms. NRG1 signaling exerts its effects via the tyrosine kinase receptors ErbB2-ErbB4. The NRG1/ErbB network in CNS pathology and repair has evolved, primarily in recent years. In the present study, we demonstrated that a unilateral microinjection of CoCl2 into the ventral hippocampus (vHPC) induced hypoxic insult and led to anxiety-related behaviors and deficit sociability in mice. NRG1 treatment significantly alleviated the CoCl2-induced increase of hypoxic-related molecules and behavioral abnormalities. Furthermore, NRG1 reduced the CoCl2-induced neuroinflammation and neuronal deficits in the vHPC or primary hippocampal neurons in mice. Collectively, these results suggest that NRG1 ameliorates hypoxia by alleviating synaptic deficits and behavioral abnormalities of the CoCl2-induced vHPC hypoxic model.

Perilipin-2 limits remyelination by preventing lipid droplet degradation.

Foamy macrophages and microglia containing lipid droplets (LDs) are a pathological hallmark of demyelinating disorders affecting the central nervous system (CNS). We and others showed that excessive accumulation of intracellular lipids drives these phagocytes towards a more inflammatory phenotype, thereby limiting CNS repair. To date, however, the mechanisms underlying LD biogenesis and breakdown in lipid-engorged phagocytes in the CNS, as well as their impact on foamy phagocyte biology and lesion progression, remain poorly understood. Here, we provide evidence that LD-associated protein perilipin-2 (PLIN2) controls LD metabolism in myelin-containing phagocytes. We show that PLIN2 protects LDs from lipolysis-mediated degradation, thereby impairing intracellular processing of myelin-derived lipids in phagocytes. Accordingly, loss of Plin2 stimulates LD turnover in foamy phagocytes, driving them towards a less inflammatory phenotype. Importantly, Plin2-deficiency markedly improves remyelination in the ex vivo brain slice model and in the in vivo cuprizone-induced demyelination model. In summary, we identify PLIN2 as a novel therapeutic target to prevent the pathogenic accumulation of LDs in foamy phagocytes and to stimulate remyelination.

Peripheral nervous system: A promising source of neuronal progenitors for central nervous system repair.

With a steadily aging population there is an increasing prevalence of neurological disorders. Given the lack of effective treatment strategies and a limited ability for the central nervous system (CNS) to regenerate endogenously, there is a critical need to better understand exogenous strategies for nervous system repair. Stem cell therapy offers a promising approach to promote the repair of neurologic tissue and function, however studies to date have been limited by various factors including challenges in harvesting donor cells from the CNS, ethical concerns regarding use of embryonic or fetal tissue, tumorigenic potential of induced pluripotent stem cells, and immune-mediated rejection of non-autologous cell sources. Here we review and propose two alternative sources of autologous cells derived from the peripheral nervous system (PNS) for CNS repair: enteric neuronal stem cells (ENSCs) and neural crest-derived Schwann cells found in subcutaneous adipose tissue (termed SAT-NSCs). ENSCs can be successfully isolated from the postnatal enteric nervous system, propagated in vitro, and transplanted successfully into models of CNS injury via both direct intracerebral injection and systemic tail vein injection. Similarly, SAT-NSCs can be readily isolated from both human and mouse adipose tissue and, although not yet utilized in models of CNS injury, have successfully been transplanted and restored function in models of colonic aganglionosis and gastroparesis. These unique sources of PNS-derived autologous cells offer an exciting option for stem cell therapies for the CNS as they have proven neurogenic potential and eliminate concerns around tumorigenic risk, ethical considerations, and immune-mediated rejection.

Defective fractalkine-CX3CR1 signaling aggravates neuroinflammation and affects recovery from cuprizone-induced demyelination.

Microglia have been implicated in multiple sclerosis (MS) pathogenesis. The fractalkine receptor CX3CR1 limits the activation of pathogenic microglia and the human polymorphic CX3CR1I249/M280 (hCX3CR1I249/M280 ) variant increases disease progression in models of MS. However, the role of hCX3CR1I249/M280 variant on microglial activation and central nervous system repair mechanisms remains unknown. Therefore, using transgenic mice expressing the hCX3CR1I249/M280 variant, we aimed to determine the contribution of defective CX3CR1 signaling to neuroinflammation and remyelination in the cuprizone model of focal demyelination. Here, we report that mice expressing hCX3CR1I249/M280 exhibit marked demyelination and microgliosis following acute cuprizone treatment. Nanostring gene expression analysis in demyelinated lesions showed that hCX3CR1I249/M280 but not CX3CR1-deficient mice up-regulated the cuprizone-induced gene profile linked to inflammatory, oxidative stress, and phagocytic pathways. Although CX3CR1-deficient (CX3CR1-KO) and fractalkine-deficient (FKN-KO) mice displayed a comparable demyelination and microglial activation phenotype to hCX3CR1I249/M280 mice, only CX3CR1-deficient and CX3CR1-WT mice showed significant myelin recovery 1 week from cuprizone withdrawal. Confocal microscopy showed that hCX3CR1I249/M280 variant inhibits the generation of cells involved in myelin repair. Our results show that defective fractalkine signaling contributes to regional differences in demyelination, and suggest that the CX3CR1 pathway activity may be a key mechanism for limiting toxic gene responses in neuroinflammation. Cover Image for this issue:https://doi.org/10.1111/jnc.15416.

Mechanotransduction: Exploring New Therapeutic Avenues in Central Nervous System Pathology.

Cells are continuously exposed to physical forces and the central nervous system (CNS) is no exception. Cells dynamically adapt their behavior and remodel the surrounding environment in response to forces. The importance of mechanotransduction in the CNS is illustrated by exploring its role in CNS pathology development and progression. The crosstalk between the biochemical and biophysical components of the extracellular matrix (ECM) are here described, considering the recent explosion of literature demonstrating the powerful influence of biophysical stimuli like density, rigidity and geometry of the ECM on cell behavior. This review aims at integrating mechanical properties into our understanding of the molecular basis of CNS disease. The mechanisms that mediate mechanotransduction events, like integrin, Rho/ROCK and matrix metalloproteinases signaling pathways are revised. Analysis of CNS pathologies in this context has revealed that a wide range of neurological diseases share as hallmarks alterations of the tissue mechanical properties. Therefore, it is our belief that the understanding of CNS mechanotransduction pathways may lead to the development of improved medical devices and diagnostic methods as well as new therapeutic targets and strategies for CNS repair.

Emerging role of neuregulin-1beta1 in pathogenesis and progression of multiple sclerosis

Emerging role of neuregulin-1beta1 in pathogenesis and progression of multiple sclerosis

Targeting lipophagy in macrophages improves repair in multiple sclerosis

ABSTRACT Foamy macrophages containing abundant intracellular myelin remnants are an important pathological hallmark of multiple sclerosis. Reducing the intracellular lipid burden in foamy macrophages is considered a promising therapeutic strategy to induce a phagocyte phenotype that promotes central nervous system repair. Recent research from our group showed that sustained intracellular accumulation of myelin-derived lipids skews these phagocytes toward a disease-promoting and more inflammatory phenotype. Our data now demonstrate that disturbed lipophagy, a selective form of autophagy that helps with the degradation of lipid droplets, contributes to the induction of this phenotype. Stimulating autophagy using the natural disaccharide trehalose reduced the lipid load and inflammatory phenotype of myelin-laden macrophages. Importantly, trehalose was able to boost remyelination in the ex vivo brain slice model and the in vivo cuprizone-induced demyelination model. In summary, our results provide a molecular rationale for impaired metabolism of myelin-derived lipids in macrophages, and identify lipophagy induction as a promising treatment strategy to promote remyelination. Abbreviations: Baf: bafilomycin a1; BMDM: bone marrow-derived macrophage; CD68: CD68 antigen; CNS: central nervous system; LD: lipid droplet; LIPE/HSL: lipase, hormone sensitive; LPS: lipopolysaccharide; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MBP: myelin basic protein; MGLL: monoglyceride lipase; MS: multiple sclerosis; NO: nitric oxide; NOS2/iNOS: nitric oxide synthase 2, inducible; ORO: oil red o; PNPLA2: patatin-like phospholipase domain containing 2; PLIN2: perilipin 2; TEM: transmission electron microscopy; TFEB: transcription factor EB; TOH: trehalose.

Crude Extracts of Bacopa Monnieri Induces Dendrite Formation in Rodent Neural Stem Cell Cultures-A Possible Use in Neuronal Injury.

Background Repair of nervous tissue injury impairs positive functional outcome. Major challenges involved are formation of new neuronal cells at the site of injury, growth and development of existing or stem cell-derived neuronal cells, and proper anatomical alignment of the cells required for the functional organization of the nervous system. Stem cells and various agents have been tried to overcome the above challenges yielding only limited positive results. Bacopa has been in frequent usage for cognitive impairment in Ayurvedic medicine. The assumption that Bacopa monnieri (BM) extracts may lead to certain specific changes at the cellular structural level benefitting the central nervous system repair, prompted us for the present study. Objective This is an in vitro study evaluating the effect of BM extracts (bacopasides and analogues) on the neuronal stem cells (NSC) culture in various concentrations. The study investigates the possibility of BM as an agent for the regeneration and differentiation of nervous tissue injury. This may have clinical and therapeutic implications. Materials and Methods NSC were harvested from the newborn albino rats, Rattus norvegicus, and the BM extracts were obtained from product “brahmi” manufactured by Himalaya Drug Company. Aqueous suspension of 2 μL of alcoholic extract of BM was locally added to the culture plates of NSC in concentrations of 5, 10, and 20 µg/mL after development of NSC in the media. The control NSC (without BM) and BM-rich NSC were simultaneously observed at regular unit intervals after inoculation. The morphological change in the NSC were observed and recorded. Result NSC could be successfully cultured from the newborn rat's brain harvested at 3 and 6 hours of birth. NSCs derived at 3 hours of birth were more primitive (predominantly neurospheres) than derived those at 6 hours of birth. BM had significant positive effect on the neurospheres, that is, dendritic formation was seen in the NSC predominating when 2 μL of suspensions containing 5 and 10 µg/mL concentration of the extracts were used but showed relatively lesser effect at concentration of 20 µg/mL. The positive effect was biologically significant. Conclusion NSC can be cultured from brain of the newborn rodent. BM and its extracts act positively on NSC in terms of dendritic formation when used in proper appropriate concentration. The study opens up a new area of research and explores newer avenues in nervous tissue injury repair. It may have future clinical implication in the treatment of injury of central and peripheral nervous tissue. However, the hypothesis needs to be validated by adequate number of experimental runs as well as in vivo studies to know the reproducibility of the findings in other centers.

In Vivo Imaging of Implanted Hyaluronic Acid Hydrogel Biodegradation.

Although the use of stem cell therapy for central nervous system (CNS) repair has shown considerable promise, it is still limited by the immediate death of a large fraction of transplanted cells owing to cell handling procedures, injection stress and host immune attack leading to poor therapeutic outcomes. Scaffolding cells in hydrogels is known to protect cells from such immediate death by shielding them from mechanical damage and by averting an immune attack after transplantation. Implanted hydrogels must eventually degrade and facilitate a safe integration of the graft with the surrounding host tissue. Hence, serial monitoring of hydrogel degradation in vivo is pivotal to optimize hydrogel compositions and overall therapeutic efficacy of the graft. We present here methods and protocols to use chemical exchange saturation transfer magnetic resonance imaging (CEST MRI) as a non-invasive, label-free imaging paradigm to monitor the degradation of composite hydrogels made up of thiolated gelatin (Gel-SH), thiolated hyaluronic acid (HA-SH), and poly (ethylene glycol) diacrylate (PEGDA), of which the stiffness and CEST contrast can be fine-tuned by simply varying the composite concentrations and mixing ratios. By individually labeling Gel-S and HA-S with two distinct near-infrared (NIR) dyes, multispectral monitoring of the relative degradation of the components can be used for long-term validation of the CEST MRI findings.

Application of developmental principles for spinal cord repair after injury.

The superiority of the mammalian central nervous system (CNS) compared with other vertebrates does not involve an advanced capacity for regeneration, and any insult results in irreversible functional loss. Spinal cord injury (SCI) is one example of CNS trauma affecting thousands of individuals, mostly young, each year. Despite enormous progress in our comprehension of the molecular and cellular mechanisms underlying the pathophysiology after SCI, also providing targets for therapeutic interventions, no efficient therapy exists as yet, emphasizing the need for further research. A breadth of studies have demonstrated that, after SCI, principles of development come into play either to promote or to prohibit spontaneous regeneration, and their appropriate manipulation has the potential to contribute towards functional recovery. In this overview, some of the most recent and important studies are discussed.These offer explicitly novel input from the field of development to the field of CNS repair regarding the modification of the inhibitory environment of the injured spinal cord - mainly referring to the glial scar - the activation of endogenous cell populations such as ependymal stem cells and oligodendrocyte precursor cells, and the developmental transcriptional program that is transiently activated in neurons after injury. Furthermore, current advances in stem cell technology are highlighted in terms of refinement and precise design of the appropriate stem cell population to be transplanted, not only for cell replacement but also for modulation of the host environment. As single-dimension applications have not yet proved clinically successful, it is suggested that combinatorial strategies tackling more than one target might be more effective.

Mesenchymal stem cell-derived exosomes regulate microglia phenotypes: a promising treatment for acute central nervous system injury.

There is growing evidence that long-term central nervous system (CNS) inflammation exacerbates secondary deterioration of brain structures and functions and is one of the major determinants of disease outcome and progression. In acute CNS injury, brain microglia are among the first cells to respond and play a critical role in neural repair and regeneration. However, microglial activation can also impede CNS repair and amplify tissue damage, and phenotypic transformation may be responsible for this dual role. Mesenchymal stem cell (MSC)-derived exosomes (Exos) are promising therapeutic agents for the treatment of acute CNS injuries due to their immunomodulatory and regenerative properties. MSC-Exos are nanoscale membrane vesicles that are actively released by cells and are used clinically as circulating biomarkers for disease diagnosis and prognosis. MSC-Exos can be neuroprotective in several acute CNS models, including for stroke and traumatic brain injury, showing great clinical potential. This review summarized the classification of acute CNS injury disorders and discussed the prominent role of microglial activation in acute CNS inflammation and the specific role of MSC-Exos in regulating pro-inflammatory microglia in neuroinflammatory repair following acute CNS injury. Finally, this review explored the potential mechanisms and factors associated with MSC-Exos in modulating the phenotypic balance of microglia, focusing on the interplay between CNS inflammation, the brain, and injury aspects, with an emphasis on potential strategies and therapeutic interventions for improving functional recovery from early CNS inflammation caused by acute CNS injury.

Biomaterial and tissue-engineering strategies for the treatment of brain neurodegeneration.

The incidence of neurodegenerative diseases is increasing due to changing age demographics and the incidence of sports-related traumatic brain injury is tending to increase over time. Currently approved medicines for neurodegenerative diseases only temporarily reduce the symptoms but cannot cure or delay disease progression. Cell transplantation strategies offer an alternative approach to facilitating central nervous system repair, but efficacy is limited by low in vivo survival rates of cells that are injected in suspension. Transplanting cells that are attached to or encapsulated within a suitable biomaterial construct has the advantage of enhancing cell survival in vivo. A variety of biomaterials have been used to make constructs in different types that included nanoparticles, nanotubes, microspheres, microscale fibrous scaffolds, as well as scaffolds made of gels and in the form of micro-columns. Among these, Tween 80-methoxy poly(ethylene glycol)-poly(lactic-co-glycolic acid) nanoparticles loaded with rhynchophylline had higher transport across a blood-brain barrier model and decreased cell death in an in vitro model of Alzheimer’s disease than rhynchophylline or untreated nanoparticles with rhynchophylline. In an in vitro model of Parkinson’s disease, trans-activating transcriptor bioconjugated with zwitterionic polymer poly(2-methacryoyloxyethyl phosphorylcholine) and protein-based nanoparticles loaded with non-Fe hemin had a similar protective ability as free non-Fe hemin. A positive effect on neuron survival in several in vivo models of Parkinson’s disease was associated with the use of biomaterial constructs such as trans-activating transcriptor bioconjugated with zwitterionic polymer poly(2-methacryoyloxyethyl phosphorylcholine) and protein-based nanoparticles loaded with non-Fe hemin, carbon nanotubes with olfactory bulb stem cells, poly(lactic-co-glycolic acid) microspheres with attached DI-MIAMI cells, ventral midbrain neurons mixed with short fibers of poly-(L-lactic acid) scaffolds and reacted with xyloglucan with/without glial-derived neurotrophic factor, ventral midbrain neurons mixed with Fmoc-DIKVAV hydrogel with/without glial-derived neurotrophic factor. Further studies with in vivo models of Alzheimer’s disease and Parkinson’s disease are warranted especially using transplantation of cells in agarose micro-columns with an inner lumen filled with an appropriate extracellular matrix material.

The age factor in optic nerve regeneration: Intrinsic and extrinsic barriers hinder successful recovery in the short-living killifish.

As the mammalian central nervous system matures, its regenerative ability decreases, leading to incomplete or non‐recovery from the neurodegenerative diseases and central nervous system insults that we are increasingly facing in our aging world population. Current neuroregenerative research is largely directed toward identifying the molecular and cellular players that underlie central nervous system repair, yet it repeatedly ignores the aging context in which many of these diseases appear. Using an optic nerve crush model in a novel biogerontology model, that is, the short‐living African turquoise killifish, the impact of aging on injury‐induced optic nerve repair was investigated. This work reveals an age‐related decline in axonal regeneration in female killifish, with different phases of the repair process being affected depending on the age. Interestingly, as in mammals, both a reduced intrinsic growth potential and a non‐supportive cellular environment seem to lie at the basis of this impairment. Overall, we introduce the killifish visual system and its age‐dependent regenerative ability as a model to identify new targets for neurorepair in non‐regenerating individuals, thereby also considering the effects of aging on neurorepair.

Extracellular vesicle-associated small heat shock proteins as therapeutic agents in neurodegenerative diseases and beyond

Increasing evidence points towards using extracellular vesicles (EVs) as a therapeutic strategy in neurodegenerative diseases such as multiple sclerosis, Parkinson's, and Alzheimer's disease. EVs are nanosized carriers that play an essential role in intercellular communication and cellular homeostasis by transporting an active molecular cargo, including a large variety of proteins. Recent publications demonstrate that small heat shock proteins (HSPBs) exhibit a beneficial role in neurodegenerative diseases. Moreover, it is defined that HSPBs target the autophagy and the apoptosis pathway, playing a prominent role in chaperone activity and cell survival. This review elaborates on the therapeutic potential of EVs and HSPBs, in particular HSPB1 and HSPB8, in neurodegenerative diseases. We conclude that EVs and HSPBs positively influence neuroinflammation, central nervous system (CNS) repair, and protein aggregation in CNS disorders. Moreover, we propose the use of HSPB-loaded EVs as advanced nanocarriers for the future development of neurodegenerative disease therapies.

Fatty Acid Synthesis in Glial Cells of the CNS.

Fatty acids (FAs) are of crucial importance for brain homeostasis and neural function. Glia cells support the high demand of FAs that the central nervous system (CNS) needs for its proper functioning. Additionally, FAs can modulate inflammation and direct CNS repair, thereby contributing to brain pathologies such Alzheimer’s disease or multiple sclerosis. Intervention strategies targeting FA synthesis in glia represents a potential therapeutic opportunity for several CNS diseases.

Recent insights on astrocyte mechanisms in CNS homeostasis, pathology, and repair.

Astrocytes play essential roles in development, homeostasis, injury, and repair of the central nervous system (CNS). Their development is tightly regulated by distinct spatial and temporal cues during embryogenesis and into adulthood throughout the CNS. Astrocytes have several important responsibilities such as regulating blood flow and permeability of the blood-CNS barrier, glucose metabolism and storage, synapse formation and function, and axon myelination. In CNS pathologies, astrocytes also play critical parts in both injury and repair mechanisms. Upon injury, they undergo a robust phenotypic shift known as "reactive astrogliosis," which results in both constructive and deleterious outcomes. Astrocyte activation and migration at the site of injury provides an early defense mechanism to minimize the extent of injury by enveloping the lesion area. However, astrogliosis also contributes to the inhibitory microenvironment of CNS injury and potentiate secondary injury mechanisms, such as inflammation, oxidative stress, and glutamate excitotoxicity, which facilitate neurodegeneration in CNS pathologies. Intriguingly, reactive astrocytes are increasingly a focus in current therapeutic strategies as their activation can be modulated toward a neuroprotective and reparative phenotype. This review will discuss recent advancements in knowledge regarding the development and role of astrocytes in the healthy and pathological CNS. We will also review how astrocytes have been genetically modified to optimize their reparative potential after injury, and how they may be transdifferentiated into neurons and oligodendrocytes to promote repair after CNS injury and neurodegeneration.

The Role of Lipids, Lipid Metabolism and Ectopic Lipid Accumulation in Axon Growth, Regeneration and Repair after CNS Injury and Disease.

Axons in the adult mammalian nervous system can extend over formidable distances, up to one meter or more in humans. During development, axonal and dendritic growth requires continuous addition of new membrane. Of the three major kinds of membrane lipids, phospholipids are the most abundant in all cell membranes, including neurons. Not only immature axons, but also severed axons in the adult require large amounts of lipids for axon regeneration to occur. Lipids also serve as energy storage, signaling molecules and they contribute to tissue physiology, as demonstrated by a variety of metabolic disorders in which harmful amounts of lipids accumulate in various tissues through the body. Detrimental changes in lipid metabolism and excess accumulation of lipids contribute to a lack of axon regeneration, poor neurological outcome and complications after a variety of central nervous system (CNS) trauma including brain and spinal cord injury. Recent evidence indicates that rewiring lipid metabolism can be manipulated for therapeutic gain, as it favors conditions for axon regeneration and CNS repair. Here, we review the role of lipids, lipid metabolism and ectopic lipid accumulation in axon growth, regeneration and CNS repair. In addition, we outline molecular and pharmacological strategies to fine-tune lipid composition and energy metabolism in neurons and non-neuronal cells that can be exploited to improve neurological recovery after CNS trauma and disease.

Role of aging-associated Treg cell accumulation in experimental autoimmune encephalomyelitis (EAE) — a model of late-onset multiple sclerosis (MS)

Abstract MS, a T cell-mediated autoimmune demyelinating disease of the central nervous system (CNS), has not been sufficiently studied in the elderly, despite instances of late-onset MS. Regulatory T (Treg) cells play an ameliorative role in MS disease onset and severity. Given that the aged immune system exhibits relatively enhanced thymic Treg cell generation and accumulated peripheral Treg cells, the role of Treg cell in aged MS patients remains to be elucidated. Using the mouse model EAE, we found that the aged mouse late-onset EAE occurs with two disease types. In Type I, EAE onset was delayed in the age mice, but the disease became more severe once onset. Alternatively, in Type II, some aged mice never developed severe symptoms than young mice until a second antigen challenge was given, which led to more a progressive disease course than their young counterparts. These features were potentially associated with a disparate distribution of Treg cells in the aged peripheral lymphoid tissues and CNS during the disease. The aged EAE mice had a higher proportion of polyclonal Treg cells in the peripheral lymphoid tissues, but a lower proportion of Treg cells specific for myelin oligodendrocyte glycoprotein (MOG) in the CNS, compared to young counterparts. Transient inhibition of accumulated polyclonal Treg cells in the periphery partially ameliorated disease severity in the aged mice, which was accompanied by increased MOG-specific Treg cells in the CNS. Therefore, we suggest that accumulated polyclonal Treg cells in the aged periphery are detrimental for CNS repair processes during neuronal inflammation in aged MS mice, potentially due to hampering trafficking of MOG-specific Treg cells into the CNS.

Spontaneous neuronal regeneration following lesioning in the brain of the leopard gecko ( Eublepharis macularius )

Among amniotes, lizards are often recognized as demonstrating some of the most striking examples of spontaneous central nervous system repair. These include regeneration of the spinal cord following loss of the tail, and the restoration of the optic nerve following transection. Several species of from one group of lizards (Lacertidae) are also reportedly capable of spontaneous generating new neurons following injury to the forebrain. Whether this regenerative capacity extends to other lizard species remains untested. Here, we address this evolutionary gap by investigating the potential for injury-mediated neurogenesis in the gekkotan lizard Eublepharis macularius, the leopard gecko. Gekkotans are estimated to have diverged from lacertids ~200 million years ago. Treatment with the antimetabolite 3-acetylpyridine (3AP) resulted in extensive neuronal loss within the cellular layer of the medial cortex, the presumptive homologue of the mammalian hippocampus. Four days following 3-AP administration, there was widespread evidence of TUNEL+ nuclei indicating cell death. Compared to untreated controls, the average loss of neurons across the medial cortex at four days post-treatment was 15.3% (range: 4.6-22.7%). Degenerative changes were matched by a marked increase in cell proliferation throughout the ventricular zone. Within 30 days, the medial cortex no longer showed evidence of cell death, and the distribution of proliferating cells had returned to baseline. Further, areas of the medial cortex damaged by 3-AP had become repopulated by NeuN+ neurons. Taken together, these findings indicate that the capacity for injury-mediated neurogenesis may be an evolutionarily conserved phenomenon among lizards, and that geckos represents a valuable research model for future studies of adult neurogenesis.