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Subventricular zone

The subventricular zone (SVZ), also known as the ventricular-subventricular zone (V-SVZ), is a thin germinal layer of neural tissue lining the lateral walls of the brain's lateral ventricles in adult mammals, serving as one of the primary sites of postnatal and adult neurogenesis where multipotent neural stem cells (NSCs) and progenitor cells proliferate to generate new neurons and glia.^[1] Located beneath the corpus callosum and encircling the ventricles, the SVZ measures approximately 0.1–3 mm in thickness and exhibits a regionally heterogeneous organization that supports ongoing brain plasticity and repair.^[2] Structurally, the SVZ is organized into distinct layers and domains, including an apical domain with ependymal cells and processes of type B1 astrocytes, an intermediate domain containing NSC bodies and transit-amplifying progenitors, and a basal domain interfacing with blood vessels and the brain parenchyma.^[1] Key cell types include type B1 cells, which function as astroglia-like NSCs expressing markers such as GFAP and Sox2; type C transit-amplifying progenitors marked by Ascl1; type A neuroblasts expressing doublecortin (DCX); multiciliated ependymal cells that form a barrier and may serve as quiescent NSCs; and supporting elements like endothelial cells, microglia, and vascular niches that regulate proliferation via signaling pathways such as EGF and Wnt/β-catenin.^[2]^[3] The SVZ's primary function is to sustain adult neurogenesis, particularly by producing neuroblasts that migrate tangentially through the rostral migratory stream (RMS) to the olfactory bulb, where they differentiate into granule cells and periglomerular interneurons, contributing thousands of new neurons daily in rodents.^[1] Beyond olfaction, SVZ-derived cells generate oligodendrocytes for myelination and, under injury conditions like stroke, provide trophic support—such as VEGF secretion—to promote vascular and neuronal repair, though neuronal replacement remains limited.^[3] In humans, SVZ neurogenesis is prominent during infancy but declines in adulthood, with structural differences like a prominent "gap" subventricular zone potentially restricting migration compared to rodents.^[1] Notably, the SVZ's activity is modulated by aging, with reduced proliferation in older individuals due to factors like increased p16^INK4a expression, and it plays roles in neurological disorders, including serving as an origin for glioblastoma through NSC transformation and contributing to Alzheimer's disease pathology via altered progenitor dynamics.^[2]^[3] These features highlight the SVZ's importance in brain homeostasis, regeneration, and therapeutic targeting for neurodegenerative conditions.

Structure

Location and organization

The subventricular zone (SVZ) is a thin layer of neural progenitor cells that lines the lateral ventricles in the mammalian brain, positioned immediately adjacent to the ependymal surface of the ventricular wall.^[4] This periventricular structure encircles the lateral walls of the ventricles, lying beneath the corpus callosum and in close proximity to the striatum.^[2] It exhibits bilateral symmetry, surrounding both lateral ventricles in a mirrored fashion across the midline.^[4] The SVZ functions as a germinal zone, extending anteriorly into the rostral migratory stream (RMS), a specialized pathway that directs migrating cells toward the olfactory bulb.^[4] Its gross organization includes regional variations in thickness, typically ranging from 0.1 to 3 mm, with notable thickening in the anterior horn where it can reach up to 10 cells deep before tapering posteriorly.^[2]^[5] These spatial characteristics provide the foundational architecture for its role as a neurogenic niche. The existence of the SVZ as a site of persistent cell proliferation in the adult brain was first demonstrated in the 1960s through autoradiography studies by Joseph Altman, who identified labeled cells in the anterior forebrain of rats following thymidine incorporation.^[6]

Histological layers

The subventricular zone (SVZ) exhibits a stratified histological organization divided into four distinct layers, based on cell density, arrangement, and functional associations, as identified through ultrastructural analyses in mammalian brains.^[7] This layering reflects a compartmentalized niche supporting cellular interactions, with each stratum contributing to the overall architecture adjacent to the lateral ventricle walls.^[8] Layer I, the ependymal layer, consists of a monolayer of multiciliated ependymal cells that directly line the ventricular lumen, forming a barrier with tight junctions and motile cilia for cerebrospinal fluid circulation.^[7] These cells feature apical surfaces arranged in pinwheel patterns around type B1 astrocyte processes, visualized via electron microscopy revealing dense microvilli and basal bodies.^[5] Extracellular matrix components, such as laminin-rich fractones—speckled basement membrane structures—anchor this layer to the underlying niche.^[9] Layer II, known as the hypocellular gap, is a sparse region primarily occupied by elongated astrocytic processes and occasional ependymal cell extensions, lacking dense cell bodies and creating a transitional zone with minimal cellularity.^[8] Electron microscopy highlights microtubule- and intermediate filament-rich projections traversing this gap, which contains laminin and other basement membrane proteins that support niche signaling.^[5] This layer's thin, acellular nature is evident in immunohistochemical preparations, separating the ependyma from deeper cellular ribbons.^[10] Layer III, the astrocyte ribbon, comprises a dense cluster of astrocyte-like cells, including neural stem cells (type B) and transit-amplifying progenitors (type C), arranged in irregular clusters or ribbons with processes extending into adjacent layers.^[7] These cells express glial fibrillary acidic protein (GFAP) as a key marker, confirmed through immunofluorescence and electron microscopy showing glycogen-rich cytoplasm and ribosomal aggregates.^[5] The layer's extracellular matrix includes laminin deposits associated with vascular elements, facilitating stem cell adhesion via integrins.^[11] Layer IV, the transitional or migratory layer, features chains of migrating neuroblasts (type A cells) interspersed with myelinated fibers and oligodendrocytes, bridging the SVZ to the surrounding parenchyma.^[8] Doublecortin (DCX) serves as a prominent marker for these immature neurons, identifiable via immunohistochemistry revealing tangential migration paths.^[5] Electron microscopy delineates this layer's heterogeneous arrangement, with neuroblast chains embedded in a laminin-containing matrix that guides migration.^[7] While the four-layer organization is conserved across mammals, variations exist by species; in rodents, the layers are more compact and pronounced, with a well-defined rostral migratory stream in layer IV, whereas in humans, the SVZ is thicker (up to several millimeters), the hypocellular gap (layer II) is more expansive and unique in scale, and layer IV shows dispersed rather than chained neuroblasts.^[12] These differences, observed through comparative histology and imaging, underscore adaptive niche architectures.^[5]

Cellular components

The subventricular zone (SVZ) comprises four primary cell types: migrating neuroblasts (Type A cells), astrocyte-like neural stem cells (Type B cells), transit-amplifying progenitors (Type C cells), and ependymal cells (Type E cells), which collectively form a structured niche supporting neurogenesis.^[13] These cells are organized into histological layers, with Type E cells forming the ependymal monolayer adjacent to the ventricular lumen, while Types A, B, and C predominate in deeper layers.^[14] Type B cells are quiescent, GFAP-positive neural stem cells exhibiting radial glia-like morphology, characterized by irregular cell bodies with light cytoplasm rich in intermediate filaments and multiple processes that extend toward the ventricle or striatum.^[15] They express markers such as GFAP, Sox2, and nestin, and constitute approximately 10-25% of SVZ cells in adult rodents, serving as the primary stem cell population.^[13]^[16] Type C cells are transit-amplifying progenitors with small, spherical or irregular shapes, electron-lucent cytoplasm, and prominent nucleoli, often clustered near Type B cells.^[13] These cells express epidermal growth factor receptor (EGFR) and Ascl1 (Mash1), and represent about 10% of the SVZ cellular population.^[16]^[1] Type A cells are immature migrating neuroblasts displaying elongated morphology with scant dark cytoplasm, abundant ribosomes and microtubules, and invaginated nuclei, enabling chain-like migration.^[13] They express polysialylated neural cell adhesion molecule (PSA-NCAM) and doublecortin (DCX), comprising roughly 50% of SVZ cells and forming tangential chains ensheathed by Type B processes.^[16]^[13] Type E cells are multiciliated ependymal cells with cuboidal to columnar morphology, featuring multiple cilia, interdigitated processes, and lipid droplets in their light cytoplasm.^[13] They express Foxj1 and vimentin, forming a single-layered barrier that separates the ventricular space from the underlying SVZ niche, and account for about 15-20% of cells in the region.^[14]^[13] Intercellular interactions in the SVZ niche involve Type B cells directly ensheathing chains of Type A neuroblasts via junctional complexes, while Type C progenitors cluster adjacent to Type B cells to form amplifying niches.^[13] Additionally, SVZ cells, particularly Type B and C, associate closely with endothelial cells in a planar vascular plexus, mediated by α6β1 integrin-laminin binding, which positions progenitors near blood vessels devoid of astrocyte or pericyte coverage. These structural relations maintain the niche architecture, with Type E cells providing a basal lamina interface.^[14]

Development

Embryonic origins

The subventricular zone (SVZ) originates during embryonic brain development from precursors in the ventricular zone (VZ), a pseudostratified neuroepithelium lining the lateral ventricles. In rodents, the initial formation of SVZ-like structures begins around embryonic day 11 (E11) to E13, when secondary progenitors delaminate from the VZ and migrate basally to form a distinct layer. These precursors give rise to the germinal niches that persist postnatally, with the majority of postnatal SVZ neural stem cells (type B1 cells) generated between E13.5 and E15.5 in mice. In humans, this process corresponds to the early second trimester (approximately 8-13 weeks gestation), when the SVZ expands significantly, supporting robust neurogenesis through intermediate progenitor amplification.^[17]^[18]^[19] Radial glia cells within the embryonic VZ serve as the primary progenitors for SVZ cells, undergoing asymmetric divisions to self-renew while producing basal progenitors that populate the nascent SVZ. These divisions occur primarily between E13.5 and E15.5 in rodents, where one daughter cell retains radial glial characteristics and the other adopts a fate committed to the SVZ lineage, such as quiescent pre-B1 cells. This asymmetric partitioning ensures the generation of regionally specified progenitors that maintain positional identity for future olfactory bulb neurogenesis. The process involves inheritance of apical-basal polarity and cytoskeletal elements, allowing daughter cells to detach from the ventricular surface and contribute to SVZ layering.^[17]^[20]^[21] Key signaling pathways orchestrate the establishment of the embryonic SVZ germinal niche, including Notch, bone morphogenetic protein (BMP), and Sonic hedgehog (Shh). Notch signaling promotes B1 cell fate while suppressing ependymal differentiation in radial glia progenitors, ensuring a balanced output of stem cell types. BMP signaling, modulated by antagonists like Noggin from emerging ependymal cells, inhibits neuronal differentiation and maintains progenitor quiescence in the SVZ anlage. Shh, particularly in ventral regions, induces progenitor identity and fate specification, with effects epigenetically sustained into postnatal stages to define dorsoventral patterning of the niche. These pathways interact to create a supportive microenvironment for SVZ formation.^[20] The transition from the embryonic VZ/SVZ to the postnatal structure involves the quiescence of pre-B1 cells around mid-gestation, followed by selective apoptosis of transient amplifying progenitors to refine the niche composition. This apoptotic pruning eliminates excess embryonic progenitors not incorporated into the adult germinal zones, allowing surviving cells to reactivate postnatally and form the organized SVZ architecture. In rodents, this shift occurs by E17.5, marking the decline of widespread embryonic neurogenesis in favor of localized adult potential.^[20]^[17]^[22]

Postnatal maturation

Following birth, the subventricular zone (SVZ) transitions from its embryonic configuration, where it arises from radial glia progenitors, to a more specialized postnatal structure supporting high levels of neurogenesis. In mice, the progenitor pool in the SVZ is largest at birth (P0), with peak production of neurons and glial cells occurring during the early postnatal period, particularly from P0 to P21, as neural stem cells (NSCs) generate a surge of olfactory interneurons and oligodendrocyte precursors that populate the olfactory bulb and corpus callosum.^[23] This proliferative phase gradually diminishes, leading to a substantial reduction in the NSC pool by adulthood compared to young animals. Within the first postnatal month in rodents, the rostral migratory stream (RMS) becomes fully established as a conduit for neuroblast migration from the SVZ to the olfactory bulb, enabling their integration into the granular and periglomerular layers to support olfactory circuit maturation.^[24] This process involves the shortening and transection of radial glia processes within hours of birth, followed by the formation of NSC endfeet on blood vessels, which stabilizes the bipolar morphology essential for directed migration along the RMS.^[25] Environmental factors significantly influence SVZ maturation during this period. Thyroid hormones promote NSC proliferation and neuronal differentiation in the postnatal SVZ by regulating gene expression and mitochondrial activity, with disruptions like hypothyroidism leading to reduced mitotic activity and altered Sox2 expression by P21.^[26] Similarly, hypoxic conditions, prevalent in the SVZ niche (2.5-3% O2), enhance NSC proliferation, migration, and maturation through hypoxia-inducible factor pathways, though severe hypoxia-ischemia can impair process length and cellularity.^[27] As maturation progresses into adulthood, the SVZ undergoes age-related decline, characterized by decreased quiescence in type B NSCs, increased cell cycle exit, and senescence, resulting in a thinner SVZ structure with ventral stenosis that restricts the neurogenic region.^[28] This leads to a 50% reduction in overall neurogenesis, underscoring the shift from a highly proliferative postnatal zone to a more quiescent adult niche.^[29]

Functions

Adult neurogenesis

The subventricular zone (SVZ) serves as one of the primary neurogenic niches in the adult mammalian brain, continuously generating new neurons that integrate into existing neural circuits, particularly in the olfactory bulb.^[30] This process, known as adult neurogenesis, begins with the activation of quiescent neural stem cells and proceeds through a series of proliferation, differentiation, and migration steps, ultimately contributing to olfactory function and potentially other brain processes.^[31] Unlike embryonic neurogenesis, adult SVZ neurogenesis is tightly regulated to maintain homeostasis, with the balance between quiescence and proliferation ensuring a steady supply of new neurons without exhausting the stem cell pool.^[32] The lineage progression in the adult SVZ starts with Type B cells, which are astrocyte-like neural stem cells characterized by their radial processes contacting the ventricular surface and blood vessels.^[33] Upon activation, Type B cells asymmetrically divide to self-renew and produce transit-amplifying Type C cells, which are highly proliferative and express markers such as Ascl1.^[7] Type C cells then rapidly divide multiple times to generate Type A cells, immature neuroblasts that express doublecortin and PSA-NCAM, marking their commitment to the neuronal fate.^[30] This stepwise lineage—Type B activation to Type C proliferation to Type A differentiation—amplifies the output from rare stem cells to yield a substantial number of neuronal progenitors.^[33] Following differentiation, Type A neuroblasts detach from the SVZ and migrate tangentially toward the olfactory bulb via the rostral migratory stream (RMS), a specialized pathway formed by glial tubes and extracellular matrix components like tenascin.^[31] In the RMS, neuroblasts travel collectively in chains at speeds of up to 800 micrometers per day, navigating through the forebrain parenchyma without disrupting existing circuitry. Upon reaching the olfactory bulb, these cells disperse radially, differentiate into granule cells or periglomerular interneurons, and integrate into local circuits, where they participate in olfactory discrimination and memory.^[30] In adult mice, this process generates thousands of new neurons per day from the SVZ, with the majority integrating as granule cells in the olfactory bulb and surviving for months to years. These rates highlight the scale of adult neurogenesis, contributing significantly to the neuronal turnover in the olfactory bulb, though the exact output varies with age and environmental factors.^[31] Extrinsic regulators play a critical role in modulating this neurogenesis pipeline. Cerebrospinal fluid (CSF) flow delivers soluble factors such as Noggin, which inhibits BMP signaling to promote Type B cell activation and progenitor survival. Vasculature-derived vascular endothelial growth factor (VEGF) supports proliferation and migration by acting on VEGFR2 receptors on Type B and Type A cells, enhancing their survival and niche vascularization.^[34] Meningeal-derived factors, including growth-promoting signals from leptomeningeal cells, further influence the SVZ niche by secreting chemokines and extracellular matrix molecules that guide neuroblast migration and maintain stem cell quiescence.^[35] While robust in rodents, evidence for adult SVZ neurogenesis in humans remains limited and controversial, with post-mortem studies using BrdU-like retrospective labeling or proliferation markers showing clusters of progenitor cells in the SVZ but unclear neuronal integration into the olfactory bulb.^[36] Early reports suggested ongoing neurogenesis similar to rodents, but subsequent analyses indicate it may decline sharply after early postnatal periods, with most SVZ cells remaining quiescent in adults. A 2024 single-cell atlas of the adult human SVZ identified multiple neural stem cell populations with multipotent potential, supporting evidence of ongoing neurogenesis and gliogenesis, though their functional integration into neural circuits remains debated.^[37]

Neural stem cell regulation

Neural stem cells (NSCs) in the subventricular zone (SVZ), primarily type B cells, are tightly regulated to balance quiescence, proliferation, and self-renewal, ensuring long-term maintenance of the stem cell pool and niche integrity. Quiescent NSCs remain dormant to prevent exhaustion, while activation allows proliferation in response to physiological demands. This regulation involves intrinsic transcriptional controls, extrinsic niche signals, feedback mechanisms, and metabolic adaptations that collectively preserve NSC homeostasis.^[38] Intrinsic factors play a central role in governing NSC quiescence and activation. The transcription factor FoxO3 promotes quiescence by inducing gene programs that inhibit cell cycle progression and prevent premature differentiation in SVZ NSCs, thereby maintaining the stem cell reservoir. Similarly, the cyclin-dependent kinase inhibitor p21 (also known as Cdkn1a) enforces quiescence through transcriptional repression of bone morphogenetic protein 2 (Bmp2), linking cell cycle arrest to sustained NSC maintenance and preventing aberrant activation. In contrast, the proneural transcription factor Ascl1 (also called Mash1) drives NSC activation and proliferation; its conditional inactivation blocks the transition from quiescence to active proliferation in SVZ type B cells, reducing the generation of downstream progenitors.^[39]^[40]^[41] Niche-derived signals further modulate NSC behavior by influencing adhesion and self-renewal within the SVZ microenvironment. Integrins, particularly the laminin receptor α6β1, mediate adhesion of SVZ NSCs to laminin-rich extracellular matrix components, such as those in fractone bulbs and vascular basement membranes, which are essential for anchoring stem cells and supporting niche integrity. Disruption of this integrin-laminin interaction impairs NSC adhesion to endothelial cells and alters proliferation dynamics. Additionally, the Wnt/β-catenin pathway promotes self-renewal in SVZ NSCs; the orphan nuclear receptor TLX activates canonical Wnt signaling via ligands like Wnt7a, stabilizing β-catenin to enhance proliferation and prevent differentiation, thus sustaining the stem cell pool.^[42]^[43]^[44] Feedback loops involving morphogens fine-tune NSC fate decisions to avoid excessive differentiation. Bone morphogenetic proteins (BMPs), secreted by radial glia-like stem cells and transit-amplifying progenitors in the SVZ, promote quiescence and astroglial lineage commitment; however, ependymal cells counteract this by secreting the BMP antagonist Noggin, which inhibits BMP signaling to favor progenitor proliferation and neuronal differentiation while preserving niche balance. This antagonistic interaction forms a local gradient that regulates NSC output without depleting the quiescent reservoir.^[45]^[46] Metabolic regulation is crucial for sustaining quiescence in type B cells, with fatty acid oxidation (FAO) serving as a primary energy source. Quiescent SVZ NSCs rely on FAO to generate ATP and support redox balance, enabling dormancy while poised for activation; inhibition of FAO disrupts this metabolic state, leading to impaired self-renewal and reduced neurogenic potential. This FAO-dependent shift distinguishes quiescent from proliferative NSCs, highlighting metabolism's role in niche stability. Through these coordinated mechanisms, SVZ NSC regulation ensures controlled progenitor production for adult neurogenesis.

Clinical and pathological relevance

Role in brain injury repair

Following brain injuries such as ischemic stroke, the subventricular zone (SVZ) responds by enhancing the proliferation of neural stem and progenitor cells, a process that amplifies baseline adult neurogenesis to support tissue repair. This injury-induced proliferation is driven primarily by upregulated signaling through epidermal growth factor (EGF) and fibroblast growth factor (FGF) pathways, which recruit quiescent type B stem cells and accelerate the division of transit-amplifying type C progenitors. Studies in rodent models demonstrate that EGF receptor (EGFR) expression in SVZ cells increases approximately 3-fold within 72 hours post-injury, heightening progenitor responsiveness to mitogenic cues and resulting in a several-fold expansion of the progenitor pool.^[47]^[48]^[49] This proliferative surge leads to reactive neurogenesis, characterized by the generation and redirected migration of neuroblasts toward damaged brain regions, such as the striatum or cortex. In response to ischemia, doublecortin-positive (DCX+) neuroblasts detach from their normal rostral migratory stream and form ectopic chains that travel to peri-infarct zones, guided by vascular and astrocytic cues. Experimental evidence from middle cerebral artery occlusion (MCAO) mouse models confirms that SVZ-derived cells constitute a significant portion of newborn cells in these areas, with up to 2% of bromodeoxyuridine (BrdU)-labeled cells in the ischemic cortex originating from the SVZ and surviving for at least 35 days post-injury.^[50]^[51] Despite these adaptive responses, the reparative potential of SVZ-derived cells is limited, as the majority differentiate into reactive astrocytes that contribute to gliosis and scar formation rather than functional neuronal integration. In MCAO models, while neuroblasts initially migrate to injured sites, most SVZ progeny adopt an astrocytic fate, exacerbating glial reactivity in the peri-infarct region without substantial neuronal replacement. Furthermore, this repair efficiency diminishes with age, as aging reduces the overall neurogenic capacity of the SVZ through decreased stem cell numbers and impaired proliferative responses to injury.^[51]^[52]

Involvement in gliomas and other tumors

The subventricular zone (SVZ) acts as a critical hotspot for the initiation of gliomas, particularly glioblastoma (GBM), owing to its rich population of neural stem cells and progenitor cells that are susceptible to oncogenic transformation. Studies indicate that 50-70% of GBMs involve or contact the SVZ, as determined by magnetic resonance imaging (MRI) analyses of patient cohorts.^[53] This proximity suggests that dysregulated progenitors within the SVZ niche contribute to tumor genesis, with type B cells—the astrocyte-like neural stem cells in the SVZ—frequently identified as the cells of origin.^[54] These cells exhibit molecular profiles overlapping with glioma stem cells, rendering them vulnerable to mutations that drive malignant progression.^[55] Tumor initiation in the SVZ often involves key genetic alterations, such as epidermal growth factor receptor (EGFR) amplification, which is present in about 40% of primary GBMs and promotes proliferation of SVZ-derived progenitors. Similarly, phosphatase and tensin homolog (PTEN) loss, occurring in 30-40% of cases, disrupts signaling pathways that normally regulate stem cell quiescence and self-renewal in the niche.^[54] In lower-grade gliomas that progress to secondary GBM, isocitrate dehydrogenase 1 (IDH1) mutations, such as R132H, transform SVZ neural stem cells by increasing 2-hydroxyglutarate levels and altering DNA methylation, leading to hyperproliferation and invasive nodules.^[56] These mutations are negatively correlated with EGFR amplification and PTEN alterations, highlighting distinct pathways of SVZ progenitor transformation depending on glioma subtype.^[56] The SVZ niche's disruption facilitates tumor spread through mechanisms mimicking normal neural migration, such as perivascular routes and pathways akin to the rostral migratory stream (RMS), allowing glioma cells to infiltrate distant brain regions.^[57] Periventricular GBMs contacting the SVZ exhibit heightened invasiveness, driven by altered extracellular matrix proteins like collagen VI and fibronectin, which correlate with poorer patient outcomes. Indeed, SVZ involvement is independently associated with reduced overall survival, with median survival dropping to around 12 months in such cases compared to longer durations for non-SVZ tumors.^[53] Evidence from human studies includes MRI observations showing recurrent GBM lesions near the SVZ in a majority of cases, supporting its role as a reservoir for tumor-initiating cells.^[54] Animal models further validate this, such as the RCAS-PDGFB transduction system, where platelet-derived growth factor B (PDGFB) delivery to SVZ progenitors in adult mice induces high-grade gliomas with high penetrance in tumor suppressor-deficient backgrounds, recapitulating human histopathological features like microvascular proliferation.^[58] These models demonstrate that SVZ-targeted oncogenes like PDGFB drive migration of transformed type B cells, mirroring clinical tumor dissemination.^[54] Recent studies as of 2025 have further highlighted the SVZ's role in GBM progression, identifying it as a reservoir of cancer stem-like cells contributing to treatment resistance in approximately 65% of cases and a potential distant origin for tumor recurrence through neural stem cell involvement.^[59]^[60]

Current research

Neuropeptide Y modulation

Neuropeptide Y (NPY) is expressed in interneurons within the subventricular zone (SVZ), as well as in subependymal cells and immature neural progenitors, forming dense networks that surround the niche and are present in cerebrospinal fluid.^[61]^[62] NPY exerts its effects through specific receptors, primarily Y1 and Y2, which are localized on SVZ cell types. The Y1 receptor is expressed on Type B neural stem cells (marked by Sox2 and nestin) and Type C transit-amplifying progenitors, facilitating direct signaling to these populations, while the Y2 receptor is predominantly presynaptic on interneurons near the rostral migratory stream but not on stem or astroglial cells.^[63]^[61] Activation of the Y1 receptor by NPY promotes proliferation of SVZ progenitors through downstream signaling pathways such as ERK MAP kinases, enhancing the generation of new neurons.^[64] In contrast, Y2 receptor signaling provides inhibitory presynaptic control, modulating neurotransmitter release to balance quiescence and prevent excessive progenitor activation, thereby maintaining niche homeostasis.^[63] These opposing actions allow NPY to fine-tune neurogenesis dynamics, with Y1 driving expansion and Y2 restraining overproliferation.^[61] Experimental evidence from receptor knockout models underscores NPY's role: Y1 receptor-deficient mice exhibit approximately 50% fewer proliferating cells (Ki-67-positive) and 57% fewer neuroblasts (DCX-positive) in the SVZ and rostral migratory stream, alongside disrupted neuroblast organization.^[61] Similarly, Y2 receptor knockouts show 39% reduced proliferation and 24% fewer neuroblasts, indicating both receptors contribute to baseline neurogenesis.^[61] Intracerebroventricular infusion of NPY in adult mice stimulates SVZ progenitor proliferation, migration, and differentiation into GABAergic neurons, with effects peaking at 48 hours for proliferation and 7 days for neuronal commitment; in Huntington's disease models from the 2010s, such infusions increased neuroblast numbers and supported post-injury recovery.^[65]^[66]^[62] NPY also interacts with other niche factors, co-released with GABA from SVZ interneurons to modulate inhibitory signaling on progenitors, and upregulating brain-derived neurotrophic factor (BDNF) expression, which guides migrating neuroblasts.^[63]^[67] These interactions position NPY as a key regulator of progenitor dynamics, integrating with broader neural stem cell control mechanisms in the SVZ.^[64]

Therapeutic potential for regeneration

The subventricular zone (SVZ) holds significant promise for regenerative therapies targeting neurological disorders, as its neural stem cells can be stimulated to enhance endogenous repair or harvested for transplantation. One key strategy involves the infusion of growth factors, such as fibroblast growth factor-2 (FGF-2), directly into the lateral ventricle to boost SVZ progenitor proliferation and neurogenesis. Studies in rodent models have demonstrated that intraventricular FGF-2 administration increases the output of neuroblasts from the SVZ, promoting their migration toward damaged brain regions like the striatum and cortex, thereby extending the zone's natural role in injury repair.^[68] Another approach is the transplantation of SVZ-derived neurospheres, which are clusters of neural stem and progenitor cells expanded in vitro, into lesion sites to replace lost neurons and support tissue recovery in conditions such as stroke and Parkinson's disease.^[69] These neurospheres have shown robust engraftment and differentiation into neurons and glia when transplanted autologously, minimizing ethical concerns associated with embryonic sources.^[70] Clinical translation of SVZ-based therapies has advanced to early-phase human trials, particularly for ischemic stroke, where mobilizing or transplanting SVZ-like neural stem cells aims to augment brain repair. For instance, Phase I/II trials using human neural stem cells derived from fetal or induced pluripotent sources—mimicking SVZ progenitors—have reported safety and preliminary efficacy in chronic stroke patients, with improvements in motor function observed up to two years post-transplantation.^[71] Ongoing Phase I/II studies initiated around 2020 evaluate intravenous or intracerebral delivery of neural stem cells to enhance SVZ output in acute stroke, showing feasibility without severe adverse events.^[72] A 2025 study reported that neural stem cell transplantation improved neurologic and motor function in adults with chronic ischemic stroke at 12 months post-transplantation.^[73] However, challenges persist, including immune rejection of allogeneic cells, which can trigger inflammation and reduce graft survival, necessitating immunosuppressive regimens or autologous sourcing to improve outcomes.^[74] Poor cell migration to target areas and limited long-term integration further complicate efficacy.^[75] Emerging techniques leverage genetic and optical tools to optimize SVZ regeneration. CRISPR-Cas9 editing of Type B neural stem cells, the quiescent SVZ progenitors, has been used to knock out aging-related inhibitors, enhancing their activation, proliferation, and migration toward neurodegenerative lesions in preclinical models.^[76] For example, targeted edits in human neural stem cells improve engraftment in brain organoids, a proxy for SVZ function, by modifying genes that regulate motility without altering pluripotency.^[77] Complementing this, optogenetics enables precise control of the SVZ niche by stimulating glutamatergic neurons in adjacent regions, which upregulates progenitor proliferation and neuroblast migration in mouse models of brain injury.^[78] Such light-activated modulation of niche signaling pathways, like those involving GABAergic interneurons, boosts endogenous regeneration while avoiding pharmacological side effects.^[79] Recent studies from 2023 to 2025 highlight SVZ's therapeutic relevance in aging and Alzheimer's disease, where age-related decline in neurogenesis impairs cognitive repair. In Alzheimer's mouse models, SVZ neural stem cell transplantation restores hippocampal connectivity and reduces amyloid-beta pathology, with secretome components like exosomes promoting neuronal survival.^[80] Multimodal analyses reveal that aging depletes the SVZ stem cell pool through epigenetic silencing, but interventions like niche rejuvenation via growth factors partially reverse this, enhancing neuroblast output in aged rodents.^[81] These findings underscore the need for trials addressing SVZ exhaustion in late-onset neurodegeneration, building on its extension of natural injury responses.^[82]

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### Summary of Postnatal Maturation of SVZ, Peak Neurogenesis, and Progenitor Pool Reduction in Mice
[24]
Aging of the Subventricular Zone Neural Stem Cell Niche - PMC - NIH
We will focus on the cellular and molecular changes associated with the aging SVZ stem cell niche and the effect aging has on SVZ functions.
[25]
Plexin-B2 Regulates the Proliferation and Migration of Neuroblasts ...
Nov 21, 2012 · As was previously established, Plexin-B2 was highly expressed in the RMS during the first postnatal week (Fig. 2A). Interestingly, in the OB ...
[26]
Transformation of radial glia into postnatal neural stem cells ...
Aug 26, 2025 · Postnatal neural stem cells (NSCs) in the ventricular-subventricular zone originate from fetal radial glia (RG), which possess NSC properties.
[27]
Thyroid Hormone Regulation of Neural Stem Cell Fate
May 23, 2019 · Stem cell niches such as the SVZ generally experience lower oxygen tensions compared to surrounding tissues, rendering them hypoxic.202 Hypoxic ...
[28]
The role of hypoxia in stem cell regulation of the central nervous ...
Nov 24, 2021 · Hypoxia can promote the proliferation, migration, and maturation of NSCs in these regions.
[29]
Rejuvenating Subventricular Zone Neurogenesis in the Aging Brain
Nov 19, 2019 · Age-Related Changes in the SVZ. A) The SVZ becomes thinner and vasculature is reduced in density and branching. The ependymal layer itself ...
[30]
Neurogenesis in Adult Subventricular Zone - PMC - PubMed Central
Along much of the lateral walls of the lateral ventricles lies the largest germinal zone of the adult mammalian brain, the SVZ (Doetsch and Alvarez-Buylla, 1996) ...Missing: BCA | Show results with:BCA
[31]
Neurogenesis in Adult Subventricular Zone - Journal of Neuroscience
Feb 1, 2002 · In adult mice, the SVZ is millimeters away from the OB; quite a journey for a cell that is just 10–30 μm long. The problem is further compounded ...
[32]
Vascular endothelial growth factor (VEGF) stimulates neurogenesis ...
Comparatively little is known regarding the possible role of VEGF in adult neurogenesis ... VEGF regulates a similarly broad range of functions in neurons.
[33]
Meninges: A Widespread Niche of Neural Progenitors for the Brain
Many of the signaling molecules, growth factors, and ECM components acting in the meningeal stem cell niche are also operational in the SVZ NSC niche, ...
[34]
ADULT NEUROGENESIS IN HUMANS: A Review of Basic Concepts ...
In an adult animal brain, neurogenesis is said to occur in the lateral subventricular zone (SVZ) and the DG of the hippocampus (Figure 1). FIGURE 1. FIGURE 1.Missing: 5000-10000 | Show results with:5000-10000
[35]
Waking up quiescent neural stem cells: Molecular mechanisms and ...
Apr 23, 2020 · Most NSCs in mammalian adult brains are quiescent, but in response to extrinsic stimuli, they can exit from quiescence and become reactivated to give rise to ...
[36]
FoxO3 regulates neural stem cell homeostasis - PubMed Central - NIH
Our findings suggest that FoxO3 regulates the NSC pool by inducing a program that promotes quiescence, prevents premature differentiation, and controls oxygen ...
[37]
Interaction Between Neurogenic Stimuli and the Gene Network ...
Also FoxO3 maintains SGZ and SVZ stem cells ... Transcriptional repression of Bmp2 by p21(Waf1/Cip1) links quiescence to neural stem cell maintenance.
[38]
A Transcriptional Mechanism Integrating Inputs from Extracellular ...
Sep 3, 2014 · Block of Activation and Proliferation of V-SVZ Stem Cells by Conditional Inactivation of Ascl1. (A–D) Labeling for the activation marker MCM2 ...
[39]
Adult SVZ stem cells lie in a vascular niche - PubMed Central - NIH
Adult SVZ progenitor cells express the laminin receptor alpha6beta1 integrin, and blocking this inhibits their adhesion to endothelial cells, altering their ...
[40]
Fractone Bulbs Derive from Ependymal Cells and Their Laminin ...
Fractones are extracellular matrix structures in the neural stem cell niche of the subventricular zone (SVZ), where they appear as round deposits named ...
[41]
Orphan nuclear receptor TLX activates Wnt/β-catenin signalling to ...
Dec 13, 2009 · Wnt7a and active β-catenin promote neural stem cell self-renewal, whereas the deletion of Wnt7a or the lentiviral transduction of axin, a β ...
[42]
The Dynamic Role of Bone Morphogenetic Proteins in Neural Stem ...
RGL stem cells and TAPs secrete BMP ligands, whereas ependymal cells secrete Noggin. BMP signaling in the SVZ promotes astroglial lineage commitment and ...Mechanisms Of Bmp Signaling · Bmp Ligands And Their... · Bmps In Early Cns...
[43]
Signaling mechanisms regulating adult neural stem cells and ...
Interestingly, the BMP inhibitor Noggin is produced by ependymal cells of the SVZ and antagonizes endogenous BMP signaling and BMP-mediated premature glial ...Wnt/beta-Catenin Pathway · Notch Pathway · Growth Factors And...
[44]
Brain injury expands the numbers of neural stem cells and ...
We show that injury recruits quiescent cells in the SVZ to proliferate, that they divide more rapidly and that there is increased EGFR expression on both ...
[45]
Stroke Repair via Biomimicry of the Subventricular Zone - Frontiers
As one example, mitogens EGF and FGF-2 are inconsistently used between laboratories to expand primitive cells. ... proliferation in stroke-injured brain.
[46]
Intrinsic regulation of adult subventricular zone neural progenitor ...
This review will cover how transcription factors regulate adult SVZ neurogenesis; the progression from neural stem cell, to transit amplifying precursor cell.Missing: meningeal | Show results with:meningeal
[47]
Increased subventricular zone-derived cortical neurogenesis after ...
Ischemic brain injury can increase neurogenesis in both neurogenic regions and promote migration of neuroblasts to the ischemic boundary in the cortex and ...
[48]
Subventricular Zone-Derived Neuroblasts Migrate and Differentiate ...
Jun 14, 2006 · We conclude that SVZ is the main source of the neuroblasts that migrate toward the brain region infarcted by cerebral ischemia, in which they differentiate ...
[49]
Age-Related Changes in Astrocytic and Ependymal Cells of the ...
In this region, NSCs are identified as a subpopulation of astrocytes called B1 astrocytes, which reside adjacent to the ependymal cells (type E cells) that ...
[50]
https://www.sciencedirect.com/science/article/abs/pii/S0014488610002888
[51]
https://www.jneurosci.org/content/26/24/6627
[52]
The Role of SVZ Stem Cells in Glioblastoma - MDPI
The ependymal layer (layer I) separates the SVZ form the lumen of the ... The ependyma is followed by the hypocellular layer (layer II), mainly containing ...
[53]
https://pmc.ncbi.nlm.nih.gov/articles/PMC5111577/
[54]
Cell of origin of glioma: biological and clinical implications - Nature
Nov 10, 2016 · Neuronal progenitor cells in the SVZ give rise to new neurons that migrate through the rostral migratory stream and into the olfactory bulb, ...
[55]
https://www.mdpi.com/2072-6694/11/4/448
[56]
https://doi.org/10.1016/j.ccell.2016.08.017
[57]
https://www.nature.com/articles/bjc2016354
[58]
Cellular targets for neuropeptide Y-mediated control of adult ...
Neuropeptide Y promotes neurogenesis in murine subventricular zone. Stem ... migration and differentiation of neural precursors from the subventricular zone ...
[59]
https://www.sciencedirect.com/science/article/pii/S2211124724015006
[60]
https://molecular-cancer.biomedcentral.com/articles/10.1186/s12943-025-02273-2
[61]
https://doi.org/10.1073/pnas.0712303105
[62]
https://doi.org/10.1111/j.1471-4159.2010.07154.x
[63]
FGF-2 promotes neurogenesis and neuroprotection and ... - PNAS
We show that FGF-2 stimulates neurogenesis, induces migration of newborn cells into the striatum and cortex, is neuroprotective in vitro, and significantly ...
[64]
Epidermal Growth Factor and Fibroblast Growth Factor-2 Have ...
Aug 1, 1997 · Both growth factors expanded the SVZ progenitor population after 2 weeks of intracerebroventricular administration, but only FGF-2 induced an ...
[65]
Adult subventricular zone neural stem cells as a potential source of ...
In this review, we discuss the potential of neural stem cells in the adult subventricular zone (SVZ) as an autologous source of replacement cells.
[66]
Transplanted Autologous Neural Stem Cells Show Promise in ...
May 8, 2023 · In this study, we aimed to investigate the efficacy of transplanting autologous NSCs isolated from the subventricular zone (SVZ-NSCs) into a ...
[67]
Human Neural Stem Cell Therapy for Chronic Ischemic Stroke - NIH
A Phase I trial has recently been published, showing no safety concerns and some promising signs of efficacy. A single-arm Phase II multicenter trial in ...
[68]
Revisiting Stem Cell-Based Clinical Trials for Ischemic Stroke
Dec 13, 2020 · Stem-cell-based clinical trials for ischemic stroke have fallen under three broad cell lineages: hematopoietic, mesenchymal, and neural.
[69]
Current Status and Challenges of Stem Cell Treatment for ...
Oct 4, 2021 · However, disadvantages include the cost, cellular dysfunction, cell death, immunogenicity of the gene product, and potential risk for ...
[70]
Beneath the radar: immune-evasive cell sources for stroke therapy
Jan 25, 2024 · The brain is not immune privileged, leading to new challenges for cell therapies. While cell therapies for stroke have been shown to enhance ...
[71]
CRISPR–Cas9 screens reveal regulators of ageing in neural stem ...
Oct 2, 2024 · Here we develop in vitro and in vivo high-throughput CRISPR–Cas9 screening platforms to systematically uncover gene knockouts that boost NSC activation in old ...
[72]
CRISPR/Cas9 Genome Engineering in Engraftable Human Brain ...
May 31, 2019 · We show that NSCs are amenable to gene targeting at multiple loci using Cas9 mRNA with synthetic chemically modified guide RNAs along with DNA donor templates.
[73]
Optogenetic stimulation of Glutamatergic Neuronal Activity in ... - NIH
We here examined the possibility that SVZ neurogenesis could be upregulated by stimulating glutamatergic activities in the striatum and this strategy could be ...
[74]
Optogenetic Stimulation Enhanced Neuronal Plasticities in Motor ...
Mar 14, 2019 · Optogenetic stimulation of SVZ, which is a niche for the genesis of neuroblasts, involves promoting neuroblasts to migrate to the boundaries ...
[75]
Neural Stem Cell Therapy for Alzheimer's Disease: A-State-of-the ...
Nov 6, 2024 · Major challenges in NSC transplantation and development include sourcing the cells and scaling up in vitro, as both autologous and allogeneic ...
[76]
Neural stem cells in aging - ScienceDirect.com
Aging negatively affects NSCs' ability to generate new neurons, with dramatically reduced neurogenesis [3,13,57,58] and smaller NSCs pool both in the SVZ of the ...
[77]
Neural stem cell secretome: a secret key to unlocking the power of ...
Jul 5, 2025 · In this review, we explore the role of adult NSCs and their secretome in sustaining brain function throughout adulthood and aging.