Deep learning for osteoarthritis classification in temporomandibular joint.

OBJECTIVES: This study aimed to develop a diagnostic support tool using pretrained models for classifying panoramic images of the temporomandibular joint (TMJ) into normal and osteoarthritis (OA) cases. SUBJECTS AND METHODS: A total of 858 panoramic images of the TMJ (395 normal and 463 TMJ-OA) were obtained from 518 individuals from January 2015 to December 2018. The data were randomly divided into training, validation, and testing sets (6:2:2). We used pretrained Resnet152 and EfficientNet-B7 as transfer learning models. The accuracy, specificity, sensitivity, area under the curve, and gradient-weighted class activation mapping (grad-CAM) of both trained models were evaluated. The performances of the trained models were compared to that of dentists (both TMD specialists and general dentists). RESULTS: The classification accuracies of ResNet-152 and EfficientNet-B7 were 0.87 and 0.88, respectively. The trained models exhibited the highest accuracy in OA classification. In the grad-CAM analysis, the trained models focused on specific areas in osteoarthritis images where erosion or osteophyte were observed. CONCLUSIONS: The artificial intelligence model improved the diagnostic power of TMJ-OA when trained with two-dimensional panoramic condyle images and can be effectively applied by dentists as a screening diagnostic tool for TMJ-OA.

Assessment of a novel deep learning-based software developed for automatic feature extraction and grading of radiographic knee osteoarthritis.

BACKGROUND: The Kellgren-Lawrence (KL) grading system is the most widely used method to classify the severity of osteoarthritis (OA) of the knee. However, due to ambiguity of terminology, the KL system showed inferior inter- and intra-observer reliability. For a more reliable evaluation, we recently developed novel deep learning (DL) software known as MediAI-OA to extract each radiographic feature of knee OA and to grade OA severity based on the KL system. METHODS: This research used data from the Osteoarthritis Initiative for training and validation of MediAI-OA. 44,193 radiographs and 810 radiographs were set as the training data and used as validation data, respectively. This AI model was developed to automatically quantify the degree of joint space narrowing (JSN) of medial and lateral tibiofemoral joint, to automatically detect osteophytes in four regions (medial distal femur, lateral distal femur, medial proximal tibia and lateral proximal tibia) of the knee joint, to classify the KL grade, and present the results of these three OA features together. The model was tested by using 400 test datasets, and the results were compared to the ground truth. The accuracy of the JSN quantification and osteophyte detection was evaluated. The KL grade classification performance was evaluated by precision, recall, F1 score, accuracy, and Cohen's kappa coefficient. In addition, we defined KL grade 2 or higher as clinically significant OA, and accuracy of OA diagnosis were obtained. RESULTS: The mean squared error of JSN rate quantification was 0.067 and average osteophyte detection accuracy of the MediAI-OA was 0.84. The accuracy of KL grading was 0.83, and the kappa coefficient between the AI model and ground truth was 0.768, which demonstrated substantial consistency. The OA diagnosis accuracy of this software was 0.92. CONCLUSIONS: The novel DL software known as MediAI-OA demonstrated satisfactory performance comparable to that of experienced orthopedic surgeons and radiologists for analyzing features of knee OA, KL grading and OA diagnosis. Therefore, reliable KL grading can be performed and the burden of the radiologist can be reduced by using MediAI-OA.

Impaction of multiple dilacerated primary incisors: a case report.

Dental complications such as defective alveolar bone development, delayed eruption, and tooth impaction are related to neonatal oral intubation. This case report presents an example of potential complications that occur in children who have undergone oral intubation as neonates. A 20-month-old girl visited our pediatric clinic. We observed delayed, non-erupted teeth #51, #71, and #81 and determined a history of intubation during the neonatal period as a related factor. After 22 months of observation, tooth #71 erupted spontaneously. After 40 months of monitoring, teeth #51 and #81 were extracted surgically, and normal permanent teeth erupted six months later. This study is helpful for pediatric anesthesiologists, pediatricians, and dentists who diagnose and treat eruption disorders of the primary dentition.

Activity-dependent release of phosphorylated human tau from Drosophila neurons in primary culture.

Neuronal activity can enhance tau release and thus accelerate tauopathies. This activity-dependent tau release can be used to study the progression of tau pathology in Alzheimer's disease (AD), as hyperphosphorylated tau is implicated in AD pathogenesis and related tauopathies. However, our understanding of the mechanisms that regulate activity-dependent tau release from neurons and the role that tau phosphorylation plays in modulating activity-dependent tau release is still rudimentary. In this study, Drosophila neurons in primary culture expressing human tau (hTau) were used to study activity-dependent tau release. We found that hTau release was markedly increased by 50 mM KCl treatment for 1 h. A similar level of release was observed using optogenetic techniques, where genetically targeted neurons were stimulated for 30 min using blue light (470 nm). Our results showed that activity-dependent release of phosphoresistant hTauS11A was reduced when compared with wildtype hTau. In contrast, release of phosphomimetic hTauE14 was increased upon activation. We found that released hTau was phosphorylated in its proline-rich and C-terminal domains using phosphorylation site-specific tau antibodies (e.g., AT8). Fold changes in detectable levels of total or phosphorylated hTau in cell lysates or following immunopurification from conditioned media were consistent with preferential release of phosphorylated hTau after light stimulation. This study establishes an excellent model to investigate the mechanism of activity-dependent hTau release and to better understand the role of phosphorylated tau release in the pathogenesis of AD since it relates to alterations in the early stage of neurodegeneration associated with increased neuronal activity.

Clinical diagnosis and treatment of temporomandibular disorders in children and adolescents: a case series.

The early diagnosis of temporomandibular disorders (TMDs) in children and adolescents is important because they can affect oral and maxillofacial growth and development. This case series introduces patients with various clinical features of TMDs and demonstrates how symptoms were reduced through appropriate interventions in collaboration with oral medicine specialists and pediatric dentists. TMDs symptoms in children are often mild and difficult to express accurately; therefore, diagnosis through clinical evaluation is important. Pediatric dentists should be aware of TMDs in children and adolescents, and should diagnose, treat, and refer to specialists in a timely manner.

Dental Management of Congenital Granular Cell Lesion and Neonatal Teeth: A Case Report.

Congenital granular cell lesion (CGCL) is a rare benign oral cavity tumor in infants. Neonatal teeth are also rare dental anomalies that appear during the first month of life. This report describes a case of eruption of neonatal teeth after surgical excision of CGCL. Surprisingly, residual neonatal teeth erupted after extraction of the neonatal teeth. If neonatal teeth are mobile, they should be carefully extracted with curettage of the underlying tissues of the dental papilla; failure to curette the socket might result in eruption of odontogenic remnants. If neonatal teeth were exfoliated, parents should be informed of the need for regular checkups with a dentist due to possibility of development of residual neonatal teeth.

Multiple Idiopathic Internal Root Resorption in an Adolescent: A Case R Multiple Idiopathic Internal Root Resorption in an Adolescent: A Case Report.

Internal root resorption (IRR) refers to a slow or rapid progressive resorption process that occurs in the pulp cavity of the tooth or the dentin of the root. IRR occurs as result of odontoclast action; in many cases, the pulp tissue exhibits chronic inflammation, and odontoblasts and predentin do not appear on the dentin wall near the pulp. Exact predisposing factors have not been clearly elucidated; therefore, it is difficult to identify reliable data on the prevalence of IRR because of its scarce occurrence and pathology. Reports have indicated that IRR is more common in the primary than in the permanent teeth. This case report discusses a 17-year-old girl with multiple idiopathic internal root resorptions of anterior permanent teeth in a short period of a time and its management.

Introduction of Reversible Urethane Bonds Based on Vanillyl Alcohol for Efficient Self-Healing of Polyurethane Elastomers.

Urethane groups formed by reacting phenolic hydroxyl groups with isocyanates are known to be reversible at high temperatures. To investigate the intrinsic self-healing of polyurethane via a reversible urethane group, we synthesized vanillyl alcohol (VA)-based polyurethanes. The phenolic hydroxyl group of vanillyl alcohol allows the introduction of a reversible urethane group into the polyurethane backbone. Particularly, we investigated the effects of varying the concentration of reversible urethane groups on the self-healing of the polyurethane, and we proposed a method that improved the mobility of the molecules contributing to the self-healing process. The concentration of reversible urethane groups in the polyurethanes was controlled by varying the vanillyl alcohol content. Increasing the concentration of the reversible urethane group worsened the self-healing property by increasing hydrogen bonding and microphase separation, which consequently decreased the molecular mobility. On the other hand, after formulating a modified chain extender (m-CE), hydrogen bonding and microphase separation decreased, and the mobility (and hence the self-healing efficiency) of the molecules improved. In VA40-10 (40% VA; 10% m-CE) heated to 140 °C, the self-healing efficiency reached 96.5% after 30 min, a 139% improvement over the control polyurethane elastomer (PU). We conclude that the self-healing and mechanical properties of polyurethanes might be tailored for applications by adjusting the vanillyl alcohol content and modifying the chain extender.

Preparation and Characterization of Isosorbide-Based Self-Healable Polyurethane Elastomers with Thermally Reversible Bonds.

Polyurethane (PU) is a versatile polymer used in a wide range of applications. Recently, imparting PU with self-healing properties has attracted much interest to improve the product durability. The self-healing mechanism conceivably occurs through the existence of dynamic reversible bonds over a specific temperature range. The present study investigates the self-healing properties of 1,4:3,6-dianhydrohexitol-based PUs prepared from a prepolymer of poly(tetra-methylene ether glycol) and 4,4'-methylenebis(phenyl isocyanate) with different chain extenders (isosorbide or isomannide). PU with the conventional chain extender 1,4-butanediol was prepared for comparison. The urethane bonds in 1,4:3,6-dianhydrohexitol-based PUs were thermally reversible (as confirmed by the generation of isocyanate peaks observed by Fourier transform infrared spectroscopy) at mildly elevated temperatures and the PUs showed good mechanical properties. Especially the isosorbide-based polyurethane showed potential self-healing ability under mild heat treatment, as observed in reprocessing tests. It is inferred that isosorbide, bio-based bicyclic diol, can be employed as an efficient chain extender of polyurethane prepolymers to improve self-healing properties of polyurethane elastomers via reversible features of the urethane bonds.

Design of Azomethine Diols for Efficient Self-Healing of Strong Polyurethane Elastomers.

Azomethine diols (AMDs) were synthesized by condensation between a terephthalic aldehyde, polyether diamine, and ethanol amine. The synthesized AMDs were employed to introduce azomethine groups into the backbones of polyurethane elastomers (PUEs). Different AMDs were designed to control the concentration and distribution of azomethine groups in PUEs. In this study, we explored the intrinsic self-healing of AMD-based PUEs by azomethine metathesis. Particularly, the effects of the concentration and distribution of the azomethine groups on the AMD-based PUEs were considered. Consequently, as the azomethine group concentration increased and the distribution became denser, the self-healing properties improved. With AMD3-40, the self-healing efficiency reached 86% at 130 °C after 30 min. This represents a 150% improvement over the control PUE. Additionally, as the AMD content increased, the mechanical properties improved. With AMD3-40, the tensile strength reached 50 MPa. Therefore, we concluded that the self-healing and mechanical properties of PUEs can potentially be tailored for applications by adjusting the concentration and design of AMD structure for PUEs.

Decompression for Unerupted Primary Mandibular Second Molars Associated with Physical Barriers: Case Reports.

Primary impaction of primary teeth might be due to genetic predisposition or physical disturbance including odontoma, supernumerary tooth, and crowded tooth. Among them, calcific deposit or odontoma is commonly associated with primary dentition. Early diagnosis and treatment is the key to prevent complications. However, results of treatment may vary depending on the condition of unerupted tooth. Here we report two clinical cases of unerupted primary mandibular second molars with physical barriers such as compound odontoma and calcific deposit focusing on diagnostic means and the importance of early treatment of these lesions.

Activation of canonical Wnt/ß-catenin signaling inhibits H2O2-induced decreases in proliferation and differentiation of human periodontal ligament fibroblasts.

Human periodontal ligament fibroblasts (hPLFs) are exposed to oxidative stress during periodontal inflammation and dental treatments. It is hypothesized that hydrogen peroxide (H2O2)-mediated oxidative stress decreases survival and osteogenic differentiation of hPLFs, whereas these decreases are prevented by activation of the Wnt pathway. However, there has been a lack of reports that define the exact roles of canonical Wnt/ß-catenin signaling in H2O2-exposed hPLFs. Treatment with H2O2 reduced viability and proliferation in hPLFs in a dose- and time-dependent manner and led to mitochondria-mediated apoptosis. Pretreatment with lithium chloride (LiCl) or Wnt1 inhibited the oxidative damage that occurred in H2O2-exposed hPLFs. However, knockout of ß-catenin or treatment with DKK1 facilitated the H2O2-induced decreases in viability, mitochondrial membrane potential, and Bcl-2 induction. Osteoblastic differentiation of hPLFs was also inhibited by combined treatment with 100 µM H2O2, as evidenced by the decreases in alkaline phosphatase (ALP) activity and mineralization. H2O2-mediated inhibition of osteoblast differentiation in hPLFs was significantly attenuated in the presence of 500 ng/ml Wnt1 or 20 mM LiCl. In particular, H2O2 stimulated the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) at protein and mRNA levels in hPLFs, whereas the induction was almost completely suppressed in the presence of Wnt1 or LiCl. Furthermore, siRNA-mediated silencing of Nrf2 blocked H2O2-induced decreases in ALP activity and mineralization of hPLFs with the concomitant restoration of runt-related transcription factor 2 and osteocalcin mRNA expression and ALP activity. Collectively, these results suggest that activation of the Wnt/ß-catenin pathway improves proliferation and mineralization in H2O2-exposed hPLFs by downregulating Nrf2.

The antibacterial activity of chlorhexidine digluconate against Streptococcus mutans biofilms follows sigmoidal patterns.

The aim of this study was to determine the pattern of the antibacterial activity of chlorhexidine digluconate (CHX) against mature Streptococcus mutans biofilms. Streptococcus mutans biofilms were formed on saliva-coated hydroxyapatite discs and then treated with 0-20% CHX, once, three times, or five times (1 min per treatment) during the period of mature biofilm formation (beyond 46 h). After the treatments, the colony-forming unit (CFU) counts of the treated biofilms were determined. The pH values of the spent culture medium were also determined to investigate the change in pH resulting from the antibacterial activity of CHX. The relationships between the concentration of CHX and the CFU counts and the concentration of CHX and culture medium pH, relative to the number of treatments performed, were evaluated using a sigmoidal curve-fitting procedure. The changes in CFU counts and culture medium pH followed sigmoidal curves and were dependent on the concentration of CHX (R2 = 0.99). The sigmoidal curves were left-shifted with increasing number of treatments. Furthermore, the culture-medium pH of the treated biofilms increased as their CFU counts decreased. The lowest CHX concentration to increase culture-medium pH above the critical pH also decreased as the number of treatments increased. These results may provide fundamental information for selecting the appropriate CHX concentrations to treat S. mutans biofilms.

Recovery of Acid Production in Streptococcus mutans Biofilms after Short-Term Fluoride Treatment.

Fluoride is commonly used as an ingredient of topical oral hygiene measures. Despite the anti-acidogenic activities of fluoride against cariogenic biofilms, the recovery of the biofilms from fluoride damage is unclear. Herein, we investigated the recovery of acid production in Streptococcus mutans biofilms after short-term or during periodic 1-min fluoride treatments. For this study, 46-hour-old S. mutans biofilms were treated with fluoride (0-2,000 ppm F-) for 1-8 min and then incubated in saliva for 0-100 min. The 74-hour-old biofilms were also periodically treated with the fluoride concentration during biofilm formation (1 min/treatment). Changes in acidogenicity and viability were determined via pH drop and colony-forming unit assays, respectively. In this study, acid production after a 1-min fluoride treatment was recovered as saliva incubation time increased, which followed a linear pattern of concentration dependence (R = 0.99, R2 = 0.98). The recovery pattern was in a biphasic pattern, with an initial rapid rate followed by a second slow recovery. Furthermore, recovery from fluoride damage was retarded in a concentration-dependent manner as treatment time increased. In periodic 1-min fluoride treatments, acid production in the biofilms was not diminished during the non-fluoride treatment period; however, it was reduced in a concentration-dependent manner during the fluoride treatment period. The viability of the biofilm cells did not change, even at high fluoride concentrations. Collectively, our results suggest that brief fluoride treatment does not sustain anti-acidogenic activity against S. mutans in biofilms since the damage is recoverable with time.

Irradiation inhibits the maturation and mineralization of osteoblasts via the activation of Nrf2/HO-1 pathway.

Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) regulates the induction of antioxidant gene expression and protects cells against oxidative injury. However, there are controversial findings regarding the roles of Nrf2 on bone metabolism under oxidative stress. The role of Nrf2 on the differentiation of radiation-exposed osteoblasts is also unclear. We investigated whether Nrf2 negatively or positively affects osteoblast differentiation in response to irradiation. Irradiation inhibited osteoblast differentiation of MC3T3-E1 cells in a dose-dependent manner. This inhibition was evidenced by the irradiation-mediated decreases in bone-like nodule formation, alkaline phosphatase (ALP) activity, calcium accumulation, and expression of osteoblast markers, such as ALP, osteocalcin, osteopontin, bone sialoprotein, osterix, and Runx2. These reductions were accompanied by increased induction of Nrf2 and heme oxygenase-1 (HO-1), accumulation of cellular oxidants, and depletion of antioxidant defense enzymes. siRNA-mediated silencing of Nrf2 markedly reversed the negative effect of irradiation on osteoblast differentiation of the cells, leading to a decrease in HO-1 and an increase in Runx2 levels. Irradiation-mediated decreases in the levels of Runx2 and osteocalcin mRNA, but not of Nrf2 protein, were also significantly inhibited by HO-1 inhibitor, zinc protoporphyrin IX. Furthermore, N-acetyl cysteine restored all of the changes induced by irradiation to near-normal levels in the cells. These results demonstrate that irradiation inhibits osteoblast differentiation and mineralization of MC3T3-E1 cells through the oxidative stress-mediated activation of Nrf2/HO-1 pathway.

The neuroprotective effect of human uncoupling protein 2 (hUCP2) requires cAMP-dependent protein kinase in a toxin model of Parkinson's disease.

Parkinson's disease (PD), caused by selective loss of dopaminergic (DA) neurons in the substantia nigra, is the most common movement disorder with no cure or effective treatment. Exposure to the mitochondrial complex I inhibitor rotenone recapitulates pathological hallmarks of PD in rodents and selective loss of DA neurons in Drosophila. However, mechanisms underlying rotenone toxicity are not completely resolved. We previously reported a neuroprotective effect of human uncoupling protein 2 (hUCP2) against rotenone toxicity in adult fly DA neurons. In the current study, we show that increased mitochondrial fusion is protective from rotenone toxicity whereas increased fission sensitizes the neurons to rotenone-induced cell loss in vivo. In primary DA neurons, rotenone-induced mitochondrial fragmentation and lethality is attenuated as the result of hucp2 expression. To test the idea that the neuroprotective mechanism of hUCP2 involves modulation of mitochondrial dynamics, we detect preserved mitochondrial network, mobility and fusion events in hucp2 expressing DA neurons exposed to rotenone. hucp2 expression also increases intracellular cAMP levels. Thus, we hypothesize that cAMP-dependent protein kinase (PKA) might be an effector that mediates hUCP2-associated neuroprotection against rotenone. Indeed, PKA inhibitors block preserved mitochondrial integrity, movement and cell survival in hucp2 expressing DA neurons exposed to rotenone. Taken together, we present strong evidence identifying a hUCP2-PKA axis that controls mitochondrial dynamics and survival in DA neurons exposed to rotenone implicating a novel therapeutic strategy in modifying the progression of PD pathogenesis.

Activation of cyclic AMP signaling pathway in dopaminergic neurons rescues locomotion defects in a Drosophila larval model of Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disease showing uncontrollable motor symptoms that are primarily caused by the progressive loss of dopaminergic neurons in the brain. Currently no treatment exists to prevent PD progression. Therefore, discovery of new neuroprotective strategies still has great potential to benefit PD patients. A handful of studies show that activation of cAMP pathways is neuroprotective against PD progression. However, the neuroprotective role of this signaling cascade specifically in DA neurons has not been explored. In this study, fruit fly Drosophila melanogaster was used because of its sophisticated and powerful genetic approaches, especially with related to cAMP signaling pathway. We have investigated molecular mechanisms of neuroprotection in a fly larval model of PD by administering an environmental PD toxin rotenone. Increased cAMP signaling in the dunce mutant fly carrying defects in phosphodiesterase (PDE) gene, is neuroprotective against rotenone-induced locomotion deficits. Furthermore, the neuroprotective role of cAMP signaling specifically in DA neurons has been studied as it has not been explored. By using transgenic flies expressing designer receptors exclusively activated by designer drugs (DREADDs), we have shown that an increase of cAMP levels in DA neurons rescues rotenone-induced locomotion deficits. We also showed that this neuroprotection is mediated by activation of Gαs and PKA-C1 subunits. The results provide novel findings that expand our knowledge of neuroprotective mechanisms in DA neurons affecting PD progression, which could contribute to the development of new therapeutic treatments against PD. An important future study will explore downstream targets of cAMP-PKA signaling.

Single dopaminergic neuron DAN-c1 in Drosophila larval brain mediates aversive olfactory learning through D2-like receptors.

The intricate relationship between the dopaminergic system and olfactory associative learning in Drosophila has been an intense scientific inquiry. Leveraging the formidable genetic tools, we conducted a screening of 57 dopaminergic drivers, leading to the discovery of DAN-c1 driver, uniquely targeting the single dopaminergic neuron (DAN) in each brain hemisphere. While the involvement of excitatory D1-like receptors is well-established, the role of D2-like receptors (D2Rs) remains underexplored. Our investigation reveals the expression of D2Rs in both DANs and the mushroom body (MB) of third instar larval brains. Silencing D2Rs in DAN-c1 via microRNA disrupts aversive learning, further supported by optogenetic activation of DAN-c1 during training, affirming the inhibitory role of D2R autoreceptor. Intriguingly, D2R knockdown in the MB impairs both appetitive and aversive learning. These findings elucidate the distinct contributions of D2Rs in diverse brain structures, providing novel insights into the molecular mechanisms governing associative learning in Drosophila larvae.

Diagnosing oral and maxillofacial diseases using deep learning.

The classification and localization of odontogenic lesions from panoramic radiographs is a challenging task due to the positional biases and class imbalances of the lesions. To address these challenges, a novel neural network, DOLNet, is proposed that uses mutually influencing hierarchical attention across different image scales to jointly learn the global representation of the entire jaw and the local discrepancy between normal tissue and lesions. The proposed approach uses local attention to learn representations within a patch. From the patch-level representations, we generate inter-patch, i.e., global, attention maps to represent the positional prior of lesions in the whole image. Global attention enables the reciprocal calibration of path-level representations by considering non-local information from other patches, thereby improving the generation of whole-image-level representation. To address class imbalances, we propose an effective data augmentation technique that involves merging lesion crops with normal images, thereby synthesizing new abnormal cases for effective model training. Our approach outperforms recent studies, enhancing the classification performance by up to 42.4% and 44.2% in recall and F1 scores, respectively, and ensuring robust lesion localization with respect to lesion size variations and positional biases. Our approach further outperforms human expert clinicians in classification by 10.7 % and 10.8 % in recall and F1 score, respectively.

Endogenous tau released from human ReNCell VM cultures by neuronal activity is phosphorylated at multiple sites.

Tau is an intracellular protein but also known to be released into the extracellular fluid. Tau release mechanisms have drawn intense attention as these are known to play a key role in Alzheimer's disease (AD) pathology. However, tau can also be released under physiological conditions although its physiological function and release mechanisms have been poorly characterized, especially in human neuronal cells. We investigated endogenous tau release in ReNCell VM, a human neuroprogenitor cell line, under physiological conditions and found that tau is spontaneously released from cells. To study activity-dependent release of endogenous tau, human ReNCell VM culture was stimulated by 100µM AMPA or 50mM KCl for one-hour, tau was actively released to the culture medium. The released tau was highly phosphorylated at nine phosphorylation sites (pSites) detected by phospho-specific tau antibodies including AT270 (T175/T181), AT8 (S202/T205), AT100 (T212/S214), AT180 (T231), and PHF-1 (S396/S404), showing that these pSites are important for activity-dependent tau release from human ReNCell VM. Intracellular tau showed various phosphorylation status across these sites, with AT270 and PHF-1 highly phosphorylated while AT8 and AT180 were minimally phosphorylated, suggesting that AT8 and AT180 pSites exhibit a propensity for secretion rather than being retained intracellularly. This activity-dependent tau release was significantly decreased by inhibition of GSK-3ß, demonstrating that GSK3ß-dependent phosphorylation of tau plays an important role in its release by neuronal activity. In this study, we showed that ReNCell VM serves as a valuable model for studying endogenous physiological tau release. Further, ReNCell model can be also used to study pathological release of human tau that will contribute to our understanding of the progression of AD and related dementias.