Extracellular vesicles (EVs) derived from human bone marrow mesenchymal stem cells (hMSCs) have great promise as biologics to treat neurological and neurodegenerative conditions due to their robust antiinflammatory and neuroprotective properties. Besides, intranasal (IN) administration of EVs has caught much attention because the procedure is noninvasive, amenable for repetitive dispensation, and leads to a quick penetration of EVs into multiple regions of the forebrain. Nonetheless, it is unknown whether brain injury-induced signals are essential for the entry of IN-administered EVs into different brain regions. Therefore, in this study, we investigated the distribution of IN-administered hMSC-derived EVs into neurons and microglia in the intact and status epilepticus (SE) injured rat forebrain. Ten billion EVs labeled with PKH26 were dispensed unilaterally into the left nostril of naïve rats, and rats that experienced two hours of kainate-induced SE. Six hours later, PKH26 + EVs were quantified from multiple forebrain regions using serial brain sections processed for different neural cell markers and confocal microscopy. Remarkably, EVs were seen bilaterally in virtually all regions of intact and SE-injured forebrain. The percentage of neurons incorporating EVs were comparable for most forebrain regions. However, in animals that underwent SE, a higher percentage of neurons incorporated EVs in the hippocampal CA1 subfield and the entorhinal cortex, the regions that typically display neurodegeneration after SE. In contrast, the incorporation of EVs by microglia was highly comparable in every region of the forebrain measured. Thus, unilateral IN administration of EVs is efficient for delivering EVs bilaterally into neurons and microglia in multiple regions in the intact or injured forebrain. Furthermore, incorporation of EVs by neurons is higher in areas of brain injury, implying that injury-related signals likely play a role in targeting of EVs into neurons, which may be beneficial for EV therapy in various neurodegenerative conditions including traumatic brain injury, stroke, multiple sclerosis, and Alzheimer’s disease.

Microglia, as the immune guardians of the central nervous system (CNS), have the ability to maintain neural homeostasis, respond to environmental changes, and remodel the synaptic landscape. However, persistent microglial activation can lead to chronic neuroinflammation, which can alter neuronal signaling pathways, resulting in accelerated cognitive decline. Phosphoinositol 3-kinase (PI3K) has emerged as a critical driver, connecting inflammation to neurodegeneration, serving as the nexus of numerous intracellular processes that govern microglial activation. This review focuses on the relationship between PI3K signaling and microglial activation, which might lead to cognitive impairment, inflammation, or even neurodegeneration. The review delves into the components of the PI3K signaling cascade, isoforms, and receptors of PI3K, as well as the downstream effects of PI3K signaling, including its effectors such as protein kinase B (Akt) and mammalian target of rapamycin (mTOR) and the negative regulator phosphatase and tensin homolog (PTEN). Experiments have shown that the overproduction of certain cytokines, coupled with abnormal oxidative stress, is a consequence of poor PI3K regulation, resulting in excessive synapse pruning and, consequently, impacting learning and memory functions. The review also highlights the implications of autonomously activated microglia exhibiting M1/M2 polarization driven by PI3K on hippocampal, cortical, and subcortical circuits. Conclusions from behavioral studies, electrophysiology, and neuroimaging linking cognitive performance and PI3K activity were evaluated, along with new approaches to therapy using selective inhibitors or gene editing. The review concludes by highlighting important knowledge gaps, including the specific effects of different isoforms, the risks associated with long-term pathway modulation, and the limitations of translational potential, underscoring the crucial role of PI3K in mitigating cognitive impairment driven by neuroinflammation.

Extracellular vesicles (EVs) released by human induced pluripotent stem cell-derived neural stem cells (hiPSC-NSCs) are enriched with miRNAs and proteins capable of mediating robust antiinflammatory activity. The lack of tumorigenic and immunogenic properties and ability to permeate the entire brain to incorporate into microglia following intranasal (IN) administrations makes them an attractive biologic for curtailing chronic neuroinflammation in neurodegenerative disorders. We tested the hypothesis that IN administrations of hiPSC-NSC-EVs can alleviate chronic neuroinflammation and cognitive impairments induced by the peripheral lipopolysaccharide (LPS) challenge. Adult male, C57BL/6J mice received intraperitoneal injections of LPS (0.75 mg/kg) for seven consecutive days. Then, the mice received either vehicle (VEH) or hiPSC-NSC-EVs (~ 10 × 10⁹ EVs/administration, thrice over 6 days). A month later, mice in all groups were investigated for cognitive function with behavioral tests and euthanized for histological and biochemical studies. Mice receiving VEH after LPS displayed deficits in associative recognition memory, temporal pattern processing, and pattern separation. Such impairments were associated with an increased incidence of activated microglia presenting NOD-, LRR-, and pyrin domain containing 3 (NLRP3) inflammasomes, elevated levels of NLRP3 inflammasome mediators and end products, and decreased neurogenesis in the hippocampus. In contrast, the various cognitive measures in mice receiving hiPSC-NSC-EVs after LPS were closer to naive mice. Significantly, these mice displayed diminished microglial activation, NLRP3 inflammasomes, proinflammatory cytokines, and a level of neurogenesis matching age-matched naïve controls. Thus, IN administrations of hiPSC-NSC-EVs are an efficacious approach to reducing chronic neuroinflammation-induced cognitive impairments.

Intranasal (IN) administrations of extracellular vesicles (EVs) derived from human‐induced pluripotent stem cell (hiPSC)‐derived neural stem cells (hNSCs) have shown promise in reducing chronic neuroinflammation mediated by microglia and astrocytes in 5x familial Alzheimer's disease (5xFAD) mice, a model for early‐onset Alzheimer's disease (AD). The current study rigorously investigated whether treatment with hiPSC‐NSC‐EVs could also alleviate several other neuropathological changes contributing to progressive cognitive decline. Three‐month‐old male and female 5xFAD mice received IN administrations of either hiPSC‐NSC‐EVs (~30 × 10 ⁹ /week for 2 weeks) or vehicle. Two months later, the hippocampus of both male and female 5xFAD mice treated with the vehicle showed increased levels of markers of oxidative stress and mechanistic target of rapamycin (mTOR) signaling, altered expression of genes and/or proteins linked to mitochondria and autophagy, and diminished neurogenesis. In contrast, treatment with hiPSC‐NSC‐EVs restored levels of oxidative stress markers and the expression of genes and/or proteins linked to various mitochondrial complexes, mitochondrial biogenesis, fission, fusion, and mitophagy closer to naïve control levels, indicating alleviation of mitochondrial impairments. These improvements were accompanied by reduced phosphorylated mTOR levels and multiple autophagy markers matching those in naïve controls, suggesting a dampening of mTOR signaling and an enhancement of autophagy. Furthermore, mice treated with hiPSC‐NSC‐EVs showed increased hippocampal neurogenesis, associated with enhanced brain‐derived neurotrophic factor signaling. Overall, the results highlight that IN administrations of hiPSC‐NSC‐EVs in the early stages of AD can help slow the progression of multiple neuropathological changes associated with cognitive decline in 5xFAD mice and potentially AD.

Background: Atrial Fibrillation (AF) poses a significant burden on the resources of the American Healthcare system. Heart failure and AF commonly coexist in patients. Elevated left ventricular and atrial pressures result in progressive left atrial dilation and remodeling which in turn predisposes to the generation of AF. Many of these patients develop pulmonary hypertension (PHT) due to the remodeling and elevated left-sided pressures. Since many who have AF could have PHT, we aimed to assess outcomes in this population. Methods: We utilized the National Inpatient Sample from 2016-2019 to identify roughly 16,500,000 hospitalized adults who had AF. These hospitalizations were further stratified based on the presence of PHT. A multivariate regression model was used to adjust for confounders and analyze the variables. Results: Of those with AF, 1,855,020 (11.2%) had PHT. In-hospital mortality was higher in those with PHT (5.6% vs 4.9%; p<0.001). Figure 1 shows the Forrest plot for multivariate analysis of in-hospital outcomes when adjusted for patient demographics, comorbidities, and hospital characteristics. When adjusted similarly, patients with AF and PHT had longer length of stay (LOS) by 0.92 days (p<0.001) and had additional hospital costs (HC) of $9,463 (p<0.001). Conclusion: In this study, patients admitted with AF with co-existing PHT had significantly worse outcomes in terms of in-hospital mortality, LOS, HC, cardiac arrest, pulmonary embolism, atrial flutter, AKI, blood transfusions, pneumonia, and endotracheal intubation. One major limitation of our study is the lack of outpatient follow up. Given that overall outcomes are worse in the setting of PHT, potential strategies for early rhythm control for AF should be pursued to avoid negative cardiac remodeling that would predispose to the development of PHT. AF patients with co-existing PHT should be aggressively monitored during hospitalizations as they have the potential to have worse outcomes.