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Background: The pathology of Alzheimer’s Disease (AD) is characterized by aggregates of amyloid beta (Aβ) peptides and neurofibrillary tau tangles. Increased blood-brain barrier (BBB) permeability and reduced Aβ clearance, which signal neurovascular dysfunction, have also been proposed as early markers of AD. Despite intense scrutiny, the mechanisms of AD remain elusive and novel treatments that address core symptoms of dementia are limited. New alternative methods (NAMs) aim to develop in-vitro translational models that recapitulate human pathology more accurately than previous models and could contribute to the development of new therapies. Methods: Here, we developed a NAM model of the cortical neurovascular unit (NVU) using brain cells derived from human induced pluripotent stem cells (hiPSCs) from a patient with AD and a healthy individual. Differentiated neurons, astrocytes, pericytes, microglia, and brain-like microvascular endothelial cells were cultured in a microphysiological system to create a brain-chip model to evaluate NVU-related endpoints. Results: Compared to control, AD brain-chips had reduced claudin-5 and ZO-1 expression and increased paracellular permeability. AD brain-chips also had decreased activity of the efflux transporter P-glycoprotein (P-gp), but its expression was unchanged. In AD brain-chips, levels of Aβ42, total tau, and p-tau 181 were decreased in protein lysates from the brain channel, while levels of total tau and p-tau 181 were increased in protein lysates from the vascular channel. Finally, AD brain-chips had increased levels of the proinflammatory markers IL-6 and MCP-1 in effluent from both brain and vascular channels. Conclusion: In this brain-chip model, we showed Aβ-independent NVU dysfunction that was related to neuroinflammation and vascular tau accumulation. This study demonstrates the utility of the brain-chip model to evaluate changes in NVU functions induced by AD-like pathology and highlights donor-specific responses associated with the use of hiPSC-derived models.

Embryonic stem cells (ESC) are pluripotent, with the potential to differentiate into multiple cell types, making them a valuable tool for regenerative medicine and disease therapy. However, common culture methods face challenges, including strict operating procedures and high costs. Currently, Leukemia inhibitory factor (LIF), an indispensable bioactive protein for ESC culture, is typically applied to maintain self-renewal and pluripotency, but its instability and high cost limit its effectiveness in stable culture conditions. Hence, we have developed an innovative strategy using a soluble nanomaterial, metal-organic polyhedra (MOPs), to effectively maintain the self-renewal and pluripotency of ESC. The selected amino-modified vanadium-based MOP not only exhibits excellent biocompatibility and high stability but also possesses similar or even superior biological functions compared to commercial LIF. Due to the precise structure of MOPs, the active site responsible for maintaining ESC pluripotency has been identified and regulated at the molecular level. The new ESC culture method significantly reduces costs, simplifies preparation, and enhances the practicality of biopharmaceutical preparation and storage. This represents the first case of using MOPs to maintain self-renewal of ECS, opening an avenue for introducing advanced materials into the development of innovative ESC culture methods. Subject terms: Biomaterials - cells, Chemical biology

Alzheimer's disease (AD) is characterized by tau pathology, leading to neurodegeneration. Astrocytes regulate central nervous system homeostasis and influence AD progression. The APOE3‐Christchurch (APOE3‐Ch) variant is linked to AD resilience, but its protective mechanisms remain unclear. Human induced pluripotent stem cell–derived astrocytes (APOE3‐Ch and wild type) were used to assess tau uptake, clearance, lipid metabolism, and transcriptomic adaptations. Fluorescently labeled 2N4R‐P301L tau oligomers were tracked, and pathway‐specific inhibitors dissected tau clearance mechanisms. Lipidomic and transcriptomic analyses were performed to identify genotype‐specific adaptations. APOE3‐Ch astrocytes exhibited enhanced tau uptake via heparan sulfate proteoglycan‐ and lipoprotein receptor‐related protein 1‐mediated pathways and superior clearance through lysosomal and proteasomal degradation. They exported less tau, limiting propagation. Transcriptomic analyses revealed upregulation of genes involved in cell projection assembly and endocytosis. Lipidomic profiling showed reduced ceramides and gamma‐linolenic acid, linked to decreased neuroinflammation and ferroptosis. APOE3‐Ch astrocytes promote tau clearance and metabolic adaptations, providing insights into genetic resilience in AD and potential therapeutic targets. APOE3‐Christchurch (APOE3‐Ch) astrocytes exhibit significantly increased tau internalization compared to wild‐type astrocytes, facilitated by upregulated heparan sulfate proteoglycan and low‐density lipoprotein receptor‐related protein 1 pathways. APOE3‐Ch astrocytes demonstrate more efficient tau degradation via both lysosomal and proteasomal pathways, while exporting significantly less tau, potentially reducing tau propagation in the central nervous system. APOE3‐Ch astrocytes show upregulation of genes involved in cell projection assembly and endocytosis, suggesting structural and functional modifications that enhance tau processing. Lipidomic profiling reveals reduced ceramide levels and gamma‐linolenic acid downregulation in APOE3‐Ch astrocytes, alterations linked to reduced neuroinflammatory and ferroptotic activity, contributing to the protective phenotype.