Evaluation of specific RBE in different cells of hippocampus under high-dose proton irradiation in rats.

The study aimed to determine the specific relative biological effectiveness (RBE) of various cells in the hippocampus following proton irradiation. Sixty Sprague-Dawley rats were randomly allocated to 5 groups receiving 20 or 30 Gy of proton or photon irradiation. Pathomorphological neuronal damage in the hippocampus was assessed using Hematoxylin-eosin (HE) staining. The expression level of NeuN, Nestin, Caspase-3, Olig2, CD68 and CD45 were determined by immunohistochemistry (IHC). The RBE range established by comparing the effects of proton and photon irradiation at equivalent biological outcomes. Proton20Gy induced more severe damage to neurons than photon20Gy, but showed no difference compared to photon30Gy. The RBE of neuron was determined to be 1.65. Similarly, both proton20Gy and proton30Gy resulted in more inhibition of oligodendrocytes and activation of microglia in the hippocampal regions than photon20Gy and photon30Gy. However, the expression of Olig2 was higher and CD68 was lower in the proton20Gy group than in the photon30Gy group. The RBE of oligodendrocyte and microglia was estimated to be between 1.1 to 1.65. For neural stem cells (NSCs) and immune cells, there were no significant difference in the expression of Nestin and CD45 between proton and photon irradiation (both 20 and 30 Gy). Therefore, the RBE for NSCs and immune cell was determined to be 1.1. These findings highlight the varying RBE values of different cells in the hippocampus in vivo. Moreover, the actual RBE of the hippocampus may be higher than 1.1, suggesting that using as RBE value of 1.1 in clinical practice may underestimate the toxicities induced by proton radiation.

Predictivism and avoidance of ad hoc-ness: An empirical study.

Predictivism is the thesis that evidence successfully predicted by a scientific theory counts more (or ought to count more) in the confirmation of that theory than already known evidence would. One rationale that has been proposed for predictivism is that predictive success guards against ad hoc hypotheses. Despite the intuitive attraction of predictivism, there is historical evidence that speaks against it. As valuable as the historical evidence may be, however, it is largely indirect evidence for the epistemic attitudes of individual - albeit prominent - scientists. This paper presents the results of an empirical study of scientists' attitudes toward predictivism and ad hoc-ness (n = 492), which will put the debate on a more robust empirical footing. The paper also draws attention to a tension between the ad hoc-ness avoidance rationale of predictivism and the ways philosophers have spelled out the notion of ad hoc-ness.

Expression of HIF-1α and Nestin in oral squamous cell carcinoma and its association with vasculogenic mimicry.

AIM: To evaluate and correlate the expression of HIF1-α and Nestin in tumor center and periphery of nonmetastatic, and recurrent oral squamous cell carcinoma (OSCC) and its association with vasculogenic mimicry. MATERIALS AND METHODS: About 60 histopathological proven cases of OSCC with proper tumor center and periphery were collected. Among them 25 are nonmetastatic, 25 metastatic, and 10 recurrent cases of OSCC. Immunohistochemical analysis of HIF, Nestin, and CD31/PAS (periodic acid Schiff) was done. RESULTS: Based on the extent of tumor cells stained, staining intensity and index score, expression of both HIF and Nestin was highly significant in periphery of metastatic OSCC with a P value of 0.003* and 0.001*. The total number of vessels expressed in nonmetastatic, metastatic, and recurrent OSCC was not significant but the overall expression of CD31/PAS was significant in the periphery of the tumor with a P value of 0.024*. Correlating the overall expression, HIF showed a positive relation with Nestin and CD31/PAS with a P value of 0.026* and 0.038* in nonmetastatic OSCC using Pearson's correlation coefficient analysis. CONCLUSION: Based on the above results hypoxia plays a vital role in cancer stem cells maintenance with the formation of vessel-like structures by tumor cells at an early stage of cancer development.

Acetylated oligopeptide and N-acetylcysteine protect against iron overload-induced dentate gyrus hippocampal degeneration through upregulation of Nestin and Nrf2/HO-1 and downregulation of MMP-9/TIMP-1 and GFAP.

Iron accumulation in the brain causes oxidative stress, blood-brain barrier (BBB) breakdown, and neurodegeneration. We examined the preventive effects of acetylated oligopeptides (AOP) from whey protein on iron-induced hippocampal damage compared to N-acetyl cysteine (NAC). This 5-week study used 40 male albino rats. At the start, all rats received 150 mg/kg/day of oral NAC for a week. The 40 animals were then randomly divided into four groups: Group I (control) received a normal diet; Group II (iron overload) received 60 mg/kg/day intraperitoneal iron dextran 5 days a week for 4 weeks; Group III (NAC group) received 150 mg/kg/day NAC and iron dextran; and Group IV (AOP group) received 150 mg/kg/day AOP and iron dextran. Enzyme-linked immunosorbent assay, spectrophotometry, and qRT-PCR were used to measure MMP-9, tissue inhibitor metalloproteinase-1 (TIMP-1), MDA, reduced glutathione (GSH) levels, and nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) gene expression. Histopathological and immunohistochemical detection of nestin, claudin, caspase, and GFAP was also done. MMP-9, TIMP-1, MDA, caspase, and GFAP rose in the iron overload group, while GSH, Nrf2, HO-1, nestin, and claudin decreased. The NAC and AOP administrations improved iron overload-induced biochemical and histological alterations. We found that AOP and NAC can protect the brain hippocampus from iron overload, improve BBB disruption, and provide neuroprotection with mostly no significant difference from healthy controls.

Absence in CX3CR1 receptor signaling promotes post-ischemic stroke cognitive function recovery through suppressed microglial pyroptosis in mice.

BACKGROUND: Post-stroke cognitive impairment (PSCI) is a major source of morbidity and mortality after stroke, but the pathological mechanisms remain unclear. Previous studies have demonstrated that the CX3CR1 receptor plays a crucial role in maintaining an early protective microenvironment after stroke, but whether it persistently influences cognitive dysfunction in the chronic phase requires further investigation. METHODS: Mouse was used to establish a middle cerebral artery occlusion (MCAO)/reperfusion model to study PSCI. Cognitive function was assessed by the Morris water maze (MWM) and the novel object recognition test. Neurogenesis was assessed by immunofluorescence staining with Nestin+ /Ki67+ and DCX+ /BrdU+ double-positive cells. The cerebral damage was monitored by [18 F]-DPA-714 positron emission tomography, Nissel, and TTC staining. The pyroptosis was histologically, biochemically, and electron microscopically examined. RESULTS: Upon MCAO, at 28 to 35 days, CX3CR1 knockout (CX3CR1-/- ) mice had better cognitive behavioral performance both in MWM and novel object recognition test than their CX3CR1+/- counterparts. Upon MCAO, at 7 days, CX3CR1-/- mice increased the numbers of Nestin+ /Ki67+ and DCX+ /BrdU+ cells, and meanwhile it decreased the protein expression of GSDMD, NLRP3 inflammasome subunit, caspase-1, mature IL-1ß/IL-18, and p-P65 in the hippocampus as compared with CX3CR1+/- mice. In addition, CX3CR1-/- mice could reverse infarct volume in the hippocampus region post-stroke. CONCLUSION: Our study demonstrated that CX3CR1 gene deletion was beneficial to PSCI recovery. The mechanism might lie in inhibited pyroptosis and enhanced neurogenesis. CX3CR1 receptor may serve as a therapeutic target for improving the PSCI.

Effect of electroacupuncture of Governor Vessel on mitochondrial fusion and proliferation and differentiation of neural stem cells in spinal cord injury rats. / ç”µé’ˆç£è„‰å¯¹è„Šé«“æŸä¼¤å¤§é¼ è„Šé«“ç»„ç»‡çº¿ç²’ä½“èžåˆåŠç¥žç»å¹²ç»†èƒžå¢žæ®–åˆ†åŒ–çš„å½±å“.

OBJECTIVES: To observe the effect of electroacupuncture (EA) at "Dazhui" (GV14) and "Jizhong"(GV6) of the Governor Vessel (GV) on mitochondrial fusion and neural stem cell (NSC) proliferation and differentiation in the spinal cord of rats with spinal cord injury (SCI), so as to investigate its mechanisms underlying improvement of SCI. METHODS: SD rats were randomly divided into sham operation, model and EA groups, with 15 rats in each group. The SCI model was established by using a precision impactor. EA (20 Hz/100 Hz, 1-2 mA) was applied to GV14 and GV6 for 30 min, once daily for 14 days. The rats' hindlimb locomotor function in each group was assessed using the Basso-Beattie-Bresnahan (BBB) locomotor scale. Histopathological changes of the injured spinal cord tissue and the number of neurons were evaluated after H.E. staining and Nissl staining. The expressions of Nestin, mitochondrial fusion-related protein optic atrophy-1 (OPA1) and NSC markers sex-determining region Y-box 2 (SOX2) in the injured spinal cord tissue were detected by immunofluorescence staining. The protein and mRNA expression levels of Nestin in the spinal cord tissue were detected by quantitative real-time PCR and Western blot, separately. RESULTS: Compared with the sham operation group, the BBB scores after modeling, and the number of neurons were significantly decreased (P<0.001), while the mean fluorescence intensity values of Nestin, SOX2 and OPA1, and the expressions of Nestin mRNA and protein considerably increased (P<0.001, P<0.01, P<0.05) in the model group. After EA intervention and in comparison with the model group, the BBB scores at the 7th and 14th day, the number of neurons, the mean fluorescence intensity values of Nestin, SOX2 and OPA1, and the expressions of Nestin mRNA and protein were strikingly increased (P<0.05, P<0.01, P<0.001) in the EA group. H.E. staining showed swollen, ruptured and necrotic neurons of the spinal cord, with a large number of vacuoles and severe inflammatory cell infiltration after modeling, which was relatively milder in the EA group. CONCLUSIONS: EA stimulation of GV14 and GV6 can promote the recovery of motor function in rats with SCI, which may be related to its effects in promoting mitochondrial fusion and enhancing the proliferation and differentiation of NSCs.

Seizure-induced LIN28A disrupts pattern separation via aberrant hippocampal neurogenesis.

Prolonged seizures can disrupt stem cell behavior in the adult hippocampus, an important brain structure for spatial memory. Here, using a mouse model of pilocarpine-induced status epilepticus (SE), we characterized spatiotemporal expression of Lin28a mRNA and proteins after SE. Unlike Lin28a transcripts, induction of LIN28A protein after SE was detected mainly in the subgranular zone, where immunoreactivity was found in progenitors, neuroblasts, and immature and mature granule neurons. To investigate roles of LIN28A in epilepsy, we generated Nestin-Cre:Lin28aloxP/loxP (conditional KO [cKO]) and Nestin-Cre:Lin28a+/+ (WT) mice to block LIN28A upregulation in all neuronal lineages after acute seizure. Adult-generated neuron- and hippocampus-associated cognitive impairments were absent in epileptic LIN28A-cKO mice, as evaluated by pattern separation and contextual fear conditioning tests, respectively, while sham-manipulated WT and cKO animals showed comparable memory function. Moreover, numbers of hilar PROX1-expressing ectopic granule cells (EGCs), together with PROX1+/NEUN+ mature EGCs, were significantly reduced in epileptic cKO mice. Transcriptomics analysis and IHC validation at 3 days after pilocarpine administration provided potential LIN28A downstream targets such as serotonin receptor 4. Collectively, our findings indicate that LIN28A is a potentially novel target for regulation of newborn neuron-associated memory dysfunction in epilepsy by modulating seizure-induced aberrant neurogenesis.

Nestin-expressing cells are mitotically active in the mammalian inner ear.

Nestin expression is associated with pluripotency. Growing evidence suggests nestin is involved in hair cell development. The objective of this study was to investigate the morphology and role of nestin-expressing cells residing in the early postnatal murine inner ear. A lineage-tracing nestin reporter mouse line was used to further characterize these cells. Their cochleae and vestibular organs were immunostained and whole-mounted for cell counting. We found Nestin-expressing cells present in low numbers throughout the inner ear. Three morphotypes were observed: bipolar, unipolar, and globular. Mitotic activity was noted in nestin-expressing cells in the cochlea, utricle, saccule, and crista. Nestin-expressing cell characteristics were then observed after hair cell ablation in two mouse models. First, a reporter model demonstrated nestin expression in a significantly higher proportion of hair cells after hair cell ablation than in control cochleae. However, in a lineage tracing nestin reporter mouse, none of the new hair cells which repopulated the organ of Corti after hair cell ablation expressed nestin, nor did the nestin-expressing cells change in morphotype. In conclusion, Nestin-expressing cells were identified in the cochlea and vestibular organs. After hair cell ablation, nestin-expressing cells did not react to the insult. However, a small number of nestin-expressing cells in all inner ear tissues exhibited mitotic activity, supporting progenitor cell potential, though perhaps not involved in hair cell regeneration.

Incomplete accumulation of perilesional reactive astrocytes exacerbates wound healing after closed-head injury by increasing inflammation and BBB disruption.

Wound healing after closed-head injury is a significant medical issue. However, conventional models of focal traumatic brain injury, such as fluid percussion injury and controlled cortical impact, employ mechanical impacts on the exposed cerebral cortex after craniotomy. These animal models are inappropriate for studying gliosis, as craniotomy itself induces gliosis. To address this, we developed a closed-head injury model and named "photo injury", which employs intense light illumination through a thinned-skull cranial window. Our prior work demonstrated that the gliosis of focal cerebral lesion after the photo injury does not encompass artificial gliosis and comprises two distinct reactive astrocyte subpopulations. The reactive astrocytes accumulated in the perilesional recovery area actively proliferate and express Nestin, a neural stem cell marker, while those in distal regions do not exhibit these traits. The present study investigated the role of perilesional reactive astrocytes (PRAs) in wound healing using the ablation of reactive astrocytes by the conditional knockout of Stat3. The extensive and non-selective ablation of reactive astrocytes in Nestin-Cre:Stat3f/f mice resulted in an exacerbation of injury, marked by increased inflammation and BBB disruption. On the other hand, GFAP-CreERT2:Stat3f/f mice exhibited the partial and selective ablation of the PRAs, while their exacerbation of injury was at the same extent as in Nestin-Cre:Stat3f/f mice. The comparison of these two mouse strains indicates that the PRAs are an essential astrocyte component for wound healing after closed-head injury, and their anti-inflammatory and regenerative functions are significantly affected even by incomplete accumulation. In addition, the reporter gene expression in the PRAs by GFAP-CreERT2 indicated a substantial elimination of these cells and an absence of differentiation into other cell types, despite Nestin expression, after wound healing. Thus, the accumulation and subsequent elimination of PRA are proposed as promising diagnostic and therapeutic avenues to bolster wound healing after closed-head injury.

Functional Hydrogel Co-Remolding Migration and Differentiation Microenvironment for Severe Spinal Cord Injury Repair.

Spinal cord injury (SCI) activates nestin+ neural stem cells (NSCs), which can be regarded as potential seed cells for neuronal regeneration. However, the lesion microenvironment seriously hinders the migration of the nestin+ cells to the lesion epicenter and their differentiation into neurons to rebuild neural circuits. In this study, a photosensitive hydrogel scaffold is prepared as drug delivery carrier. Genetically engineered SDF1α and NT3 are designed and the scaffold is binary modified to reshape the lesion microenvironment. The binary modified scaffold can effectively induce the migration and neuronal differentiation of nestin+ NSCs in vitro. When implanted into a rat complete SCI model, many of the SCI-activated nestin+ cells migrate into the lesion site and give rise to neurons in short-term. Meanwhile, long-term repair results also show that implantation of the binary modified scaffold can effectively promote the maturation, functionalization and synaptic network reconstruction of neurons in the lesion site. In addition, animals treated with binary scaffold also showed better improvement in motor functions. The therapeutic strategy based on remolding the migration and neuronal differentiation lesion microenvironment provides a new insight into SCI repair by targeting activated nestin+ cells, which exhibits excellent clinical transformation prospects.

Neuronal damage and inflammatory biomarkers are associated with the affective and chronic fatigue-like symptoms due to end-stage renal disease.

BACKGROUND: Many biochemical, immunological, and neuropsychiatric changes are associated with end-stage renal disease (ESRD). Neuronal damage biomarkers such as glial fibrillary acidic protein (GFAP), neurofilament light chain (NFL), S100 calcium-binding protein B (S100B), ionized calcium-binding adaptor molecule-1 (IBA1), and myelin basic protein (MBP) are among the less-studied biomarkers of ESRD. AIM: We examined the associations between these neuro-axis biomarkers, inflammatory biomarkers, e.g., C-reactive protein (CRP), interleukin (IL-6), IL-10, and zinc, copper, and neuropsychiatric symptoms due to ERSD. METHODS: ELISA techniques were used to measure serum levels of neuronal damage biomarkers in 70 ESRD patients, and 46 healthy controls. RESULTS: ESRD patients have higher scores of depression, anxiety, fatigue, and physiosomatic symptoms than healthy controls. Aberrations in kidney function tests and the number of dialysis interventions are associated with the severity of depression, anxiety, fibro-fatigue and physiosomatic symptoms, peripheral inflammation, nestin, and NFL. Serum levels of neuronal damage biomarkers (NFL, MBP, and nestin), CRP, and interleukin (IL)-10 are elevated, and serum zinc is decreased in ESRD patients as compared with controls. The neuronal damage biomarkers NFL, nestin, S100B and MBP are associated with the severity of one or more neuropsychiatric symptom domains. Around 50 % of the variance in the neuropsychiatric symptoms is explained by NFL, nestin, S00B, copper, and an inflammatory index. CONCLUSIONS: The severity of renal dysfunction and/or the number of dialysis interventions may induce peripheral inflammation and, consequently, neurotoxicity to intermediate filament proteins, astrocytes, and the blood-brain barrier, leading to the neuropsychiatric symptoms of ESRD.

Wound-healing Processes After Pulpotomy in the Pulp Tissue of Type 1 Diabetes Mellitus Model Rats.

INTRODUCTION: Patients with type 1 diabetes mellitus (DM1) tend to have delayed wound healing, even in the pulp tissue. We hypothesized that hyperglycemia affects odontoblast-like cell (OLC) differentiation and is involved in macrophage polarization. Accordingly, we evaluated dental pulp stem cell differentiation and macrophage phenotypes after pulpotomy. METHODS: After modifying DM1 rat models by streptozotocin, 8-week-old rats' upper left first molars were pulpotomized with mineral trioxide aggregate. Meanwhile, the control group was administered saline. Immunohistochemical localization of nestin, osteopontin, α-smooth muscles (α-SMAs), and CD68 (pan-macrophage marker) was conducted 7 days after pulpotomy. The OLC differentiation stage was determined using double immunofluorescence of nestin and α-SMA. Double immunofluorescence of CD68 and iNOS was counted as M1 macrophages and CD68 and CD206 as M2 macrophages. Proliferating cell nuclear antigen and Thy-1 (CD90) were evaluated by immunofluorescence. RESULTS: In DM1 rats, the reparative dentin bridge was not complete; however, the osteopontin-positive area did not differ significantly from that in controls. Proliferating cell nuclear antigen, indicative of cell proliferation, increased in positive cells in DM1 rats compared with controls. Double-positive cells for α-SMA and nestin indicated many immature OLCs in DM1. CD90 was positive only in controls. CD68-positive cells, especially M1 macrophages, were increased in DM1 rats, allowing the inflammatory stage to continue 7 days after pulpotomy. CONCLUSIONS: The condition of DM1 model rats can interfere at various stages of the wound healing process, altering OLC differentiation and macrophage polarization. These findings highlight the importance of normal blood glucose concentrations during pulp wound healing.

Effect of Electroacupuncture Stimulation on Proliferation and Differentiation of Endogenous Neural Stem Cells in Rats with Spinal Cord Injury.

The aim of this work was to investigate the effects of electroacupuncture (EA) stimulation on the proliferation and differentiation of endogenous neural stem cells (NSCs) in rats with spinal cord injury (SCI). One hundred rats were included and randomly divided into the sham-operation (SO) group, model (MO) group, EA group, and preacupuncture stimulation (PAS) group, with 25 rats in each group. All the rats in the SO group had their spinal cord of thoracic segment T10 exposed but without SCI. In the remaining three groups, the modified Allen's weight dropping method was adopted to make SCI models. Those in the SO group and the MO group did not receive any treatment. Those in the EA group were treated with EA after the modelling was completed, which stopped when the samples were collected at each time point. The spinal cord tissue of rats was subjected to immunohistochemical staining and real-time quantitative polymerase chain reaction (PCR) to detect the expressions of neurofilament nestin and glial fibrillary acidic protein (GFAP). The Basso-Beattie-Bresnahan (BBB) score of the MO group was much lower than that of the SO group on the 3rd, 7th, and 14th days after surgery (P < 0.05). The BBB scores of the EA group and PAS group were notably higher than that of the MO group (P < 0.05). The number of nestin-, GFAP-, and MAP-2-positive cells was significantly increased in rat tissues after spinal cord injury. On the 3rd, 7th, and 14th days postoperatively, the numbers of nestin-positive cells in the EA and PAS groups were considerably higher than those in the MO group (P < 0.01). However, the numbers of GFAP-positive cells in the EA and PAS groups were considerably decreased compared with those in the MO group (P < 0.01). The positive rate of MAP-2 in the model group was significantly increased compared to that in the sham-operation group (P < 0.001). The positive rates of MAP-2 in the EA group and PAS group were significantly higher than those in the MO group (P < 0.01). After spinal cord injury, EA could activate the proliferation of endogenous NSCs and promote their differentiation into neuronal cells. Consequently, injuries were repaired, and functions were rehabilitated.

Cardiac remodeling associated with chronic kidney disease is enhanced in a rat model of metabolic syndrome: Preparation of mesenchymal transition.

Cardiac alteration due to chronic kidney disease is described by tissue fibrosis. This remodeling involves myofibroblasts of various origins, including epithelial or endothelial to mesenchymal transitions. In addition, obesity and insulin resistance together or separately seem to exacerbate cardiovascular risk in chronic kidney disease (CKD). The main objective of this study was to assess if pre-existing metabolic disease exacerbates CKD-induced cardiac alterations. In addition, we hypothesised that endothelial to mesenchymal transition participates in this enhancement of cardiac fibrosis. Rats fed cafeteria type diet for 6 months underwent a subtotal nephrectomy at 4 months. Cardiac fibrosis was evaluated by histology and qRT-PCR. Collagens and macrophages were quantified by immunohistochemistry. Endothelial to mesenchymal transitions were assessed by qRT-PCR (CD31, VE-cadherin, α-SMA, nestin) and also by CD31 immunofluorescence staining. Rats fed with cafeteria type regimen were obese, hypertensive and insulin resistant. Cardiac fibrosis was predominant in CKD rats and was highly majored by cafeteria regimen. Collagen-1 and nestin expressions were higher in CKD rats, independently of regimen. Interestingly, in rats with CKD and cafeteria diet we found an increase of CD31 and α-SMA co-staining with suggest an implication of endothelial to mesenchymal transition during heart fibrosis. We showed that rats already obese and insulin resistant had an enhanced cardiac alteration to a subsequent renal injury. Cardiac fibrosis process could be supported by a involvement of the endothelial to mesenchymal transition phenomenon.

IFN-γ promotes radioresistant Nestin-expressing progenitor regeneration in the developing cerebellum by augmenting Shh ligand production.

BACKGROUND: Patients with brain tumors, especially pediatric brain tumors such as cerebellar medulloblastoma, always suffer from the severe side effects of radiotherapy. Regeneration of neural cells in irradiation-induced cerebellar injury has been reported, but the underlying mechanism remains elusive. METHODS: We established an irradiation-induced developing cerebellum injury model in neonatal mice. Microarray, KEGG analysis and semi in vivo slice culture were performed for mechanistic study. RESULTS: Nestin-expressing progenitors (NEPs) but not granule neuron precursors (GNPs) were resistant to irradiation and able to regenerate after irradiation. NEPs underwent less apoptosis but similar DNA damage following irradiation compared with GNPs. Subsequently, they started to proliferate and contributed to granule neurons regeneration dependent on the sonic hedgehog (Shh) pathway. In addition, irradiation increased Shh ligand provided by Purkinje cells. And microglia accumulated in the irradiated cerebellum producing more IFN-γ, which augmented Shh ligand production to promote NEP proliferation. CONCLUSIONS: NEP was radioresistant and regenerative. IFN-γ was increased post irradiation to upregulate Shh ligand, contributing to NEP regeneration. Our study provides insight into the mechanisms of neural cell regeneration in irradiation injury of the developing cerebellum and will help to develop new therapeutic targets for minimizing the side effects of radiotherapy for brain tumors.

SARM1 Promotes Neurodegeneration and Memory Impairment in Mouse Models of Alzheimer's Disease.

Neuroinflammation plays a crucial role in the pathogenesis and progression of Alzheimer's disease (AD). The Sterile Alpha and Toll Interleukin Receptor Motif-containing protein 1 (SARM1) has been shown to promote axonal degeneration and is involved in neuroinflammation. However, the role of SARM1 in AD remains unclear. In this study, we found that SARM1 was reduced in hippocampal neurons of AD model mice. Interestingly, conditional knockout (CKO) of SARM1 in the central nervous system (CNS, SARM1Nestin-CKO mice) delayed the cognitive decline in APP/PS1 AD model mice. Furthermore, SARM1 deletion reduced the Aß deposition and inflammatory infiltration in the hippocampus and inhibited neurodegeneration in APP/PS1 AD model mice. Further investigation into the underlying mechanisms revealed that the signaling of tumor necrosis factor-α (TNF-α) was downregulated in the hippocampus tissues of APP/PS1;SARM1Nestin-CKO mice, thereby alleviating the cognitive decline, Aß deposition and inflammatory infiltration. These findings identify unrecognized functions of SARM1 in promoting AD and reveal the SARM1-TNF-α pathway in AD model mice.

Homer1 ameliorates ischemic stroke by inhibiting necroptosis-induced neuronal damage and neuroinflammation.

OBJECTIVE: Proinflammatory necroptosis is the main pathological mechanism of ischemic stroke. Homer scaffolding protein 1 (Homer1) is a postsynaptic scaffolding protein that exerts anti-inflammatory effects in most central nervous system diseases. However, the relationship between Homer1 and proinflammatory necroptosis in ischemic stroke remains unclear. AIM: This study aimed to investigate the role of Homer1 in ischemia-induced necroptosis. METHODS: C57BL/6 mice were used to establish a model of permanent middle cerebral artery occlusion model (pMCAO). Homer1 knockdown mice were generated using adeno-associated virus (AAV) infection to explore the role of Homer1 and its impact on necroptosis in pMCAO. Finally, Homer1 protein was stereotaxically injected into the ischemic cortex of Homer1flox/flox/Nestin-Cre +/- mice, and the efficacy of Homer1 was investigated using behavioral assays and molecular biological assays to explore potential mechanisms. RESULTS: Homer1 expression peaked at 8 h in the ischemic penumbral cortex after pMCAO and colocalized with neurons. Homer1 knockdown promoted neuronal death by enhancing necroptotic signaling pathways and aggravating ischemic brain damage in mice. Furthermore, the knockdown of Homer1 enhanced the expression of proinflammatory cytokines. Moreover, injection of Homer1 protein reduced necroptosis-induced brain injury inhibited the expression of proinflammatory factors, and ameliorated the outcomes in the Homer1flox/flox/Nestin-Cre+/- mice after pMCAO. CONCLUSIONS: Homer1 ameliorates ischemic stroke by inhibiting necroptosis-induced neuronal damage and neuroinflammation. These data suggested that Homer1 is a novel regulator of neuronal death and neuroinflammation.

Interactions of Neuronally Induced Stem Cells from Apical Papilla Spheres, Stems Cells from Apical Papilla, and Human Umbilical Vascular Endothelial Cells on Vasculogenesis and Neurogenesis.

INTRODUCTION: Stem cell-based dental pulp regeneration has been extensively studied, mainly focusing on exploiting dental stem cells' osteogenic and angiogenic potentials. Dental stem cells' neurogenic role is often overlooked. Stem cells from apical papilla (SCAPs), originating from the neural crest and capable of sphere formation, display potent neurogenic capacity. This study aimed to investigate the interactions of neuronally induced stem cells from apical papilla (iSCAP) spheres, SCAPs, and human umbilical vascular endothelial cells (HUVECs) on vasculogenesis and neurogenesis. METHODS: SCAPs were isolated and characterized using flow cytometry and multilineage differentiation assays. SCAP monolayer culture and spheres were neuronally induced by a small molecule neural induction medium, and the neural gene expression and neurite formation at days 0, 3, and 7 were evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and using phase-contrast light and fluorescence microscopy. Direct coculture or pulp-on-chip was used to investigate iSCAP sphere interaction with SCAPs and HUVECs. RT-qPCR, fluorescence microscopy, and immunostaining with ß-tubulin III, alpha-smooth muscle actin, and CD31 were used to study neural gene expression, neurite formation, and neurovascular cell interactions. RESULTS: Neural induction medium with small molecules rapidly induced SCAP differentiation toward neural-like cells. Gene expression of Nestin, ß-tubulin III, microtubule-associated protein 2, neuron-specific enolase, and NeuN was higher in iSCAP spheres than in iSCAPs. iSCAP spheres formed more and longer neurites compared with iSCAPs. iSCAP sphere, HUVEC, and SCAP direct coculture significantly enhanced vessel formation along with up-regulated VEGF (P < .001) and multiple neural markers, such as Nestin (P < .01), microtubule-associated protein 2 (P < .001), S100 (P < .001), and NG2 (P < .001). iSCAP spheres, SCAPs, and HUVECs cultured in a pulp-on-chip system promoted endothelial and neural cell migration toward each other and alpha-smooth muscle actin-positive and CD31-positive cells assembling for the vascular constitution. CONCLUSIONS: iSCAP-formed spheres interact with SCAPs and HUVECs, promoting vasculogenesis and neurogenesis.