Endogenous Extracellular Vesicles Participate in Brain Remodeling after Ischemic Stroke.

Brain remodeling after an ischemic stroke represents a promising avenue for exploring the cellular mechanisms of endogenous brain repair. A deeper understanding of these mechanisms is crucial for optimizing the safety and efficacy of neuroprotective treatments for stroke patients. Here, we interrogated the role of extracellular vesicles, particularly exosomes, as potential mediators of endogenous repair within the neurovascular unit (NVU). We hypothesized that these extracellular vesicles may play a role in achieving transient stroke neuroprotection. Using the established ischemic stroke model of middle cerebral artery occlusion in adult rats, we detected a surged in the extracellular vesicle marker CD63 in the peri-infarct area that either juxtaposed or co-localized with GFAP-positive glial cells, MAP2-labeled young neurons, and VEGF-marked angiogenic cells. This novel observation that CD63 exosomes spatially and temporally approximated glial activation, neurogenesis, and angiogenesis suggests that extracellular vesicles, especially exosomes, contribute to the endogenous repair of the NVU, warranting exploration of extracellular vesicle-based stroke therapeutics.

Inflammatory gut as a pathologic and therapeutic target in Parkinson's disease.

Parkinson's disease (PD) remains a significant unmet clinical need. Gut dysbiosis stands as a PD pathologic source and therapeutic target. Here, we assessed the role of the gut-brain axis in PD pathology and treatment. Adult transgenic (Tg) α-synuclein-overexpressing mice served as subjects and were randomly assigned to either transplantation of vehicle or human umbilical cord blood-derived stem cells and plasma. Behavioral and immunohistochemical assays evaluated the functional outcomes following transplantation. Tg mice displayed typical motor and gut motility deficits, elevated α-synuclein levels, and dopaminergic depletion, accompanied by gut dysbiosis characterized by upregulation of microbiota and cytokines associated with inflammation in the gut and the brain. In contrast, transplanted Tg mice displayed amelioration of motor deficits, improved sparing of nigral dopaminergic neurons, and downregulation of α-synuclein and inflammatory-relevant microbiota and cytokines in both gut and brain. Parallel in vitro studies revealed that cultured dopaminergic SH-SY5Y cells exposed to homogenates of Tg mouse-derived dysbiotic gut exhibited significantly reduced cell viability and elevated inflammatory signals compared to wild-type mouse-derived gut homogenates. Moreover, treatment with human umbilical cord blood-derived stem cells and plasma improved cell viability and decreased inflammation in dysbiotic gut-exposed SH-SY5Y cells. Intravenous transplantation of human umbilical cord blood-derived stem/progenitor cells and plasma reduced inflammatory microbiota and cytokine, and dampened α-synuclein overload in the gut and the brain of adult α-synuclein-overexpressing Tg mice. Our findings advance the gut-brain axis as a key pathological origin, as well as a robust therapeutic target for PD.

Gut-Brain Axis as a Pathological and Therapeutic Target for Neurodegenerative Disorders.

Human lifestyle and dietary behaviors contribute to disease onset and progression. Neurodegenerative diseases (NDDs), considered multifactorial disorders, have been associated with changes in the gut microbiome. NDDs display pathologies that alter brain functions with a tendency to worsen over time. NDDs are a worldwide health problem; in the US alone, 12 million Americans will suffer from NDDs by 2030. While etiology may vary, the gut microbiome serves as a key element underlying NDD development and prognosis. In particular, an inflammation-associated microbiome plagues NDDs. Conversely, sequestration of this inflammatory microbiome by a correction in the dysbiotic state of the gut may render therapeutic effects on NDDs. To this end, treatment with short-chain fatty acid-producing bacteria, the main metabolites responsible for maintaining gut homeostasis, ameliorates the inflammatory microbiome. This intimate pathological link between the gut and NDDs suggests that the gut-brain axis (GBA) acts as an underexplored area for developing therapies for NDDs. Traditionally, the classification of NDDs depends on their clinical presentation, mostly manifesting as extrapyramidal and pyramidal movement disorders, with neuropathological evaluation at autopsy as the gold standard for diagnosis. In this review, we highlight the evolving notion that GBA stands as an equally sensitive pathological marker of NDDs, particularly in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and chronic stroke. Additionally, GBA represents a potent therapeutic target for treating NDDs.

Treating Metastatic Brain Cancers With Stem Cells.

Stem cell therapy may present an effective treatment for metastatic brain cancer and glioblastoma. Here we posit the critical role of a leaky blood-brain barrier (BBB) as a key element for the development of brain metastases, specifically melanoma. By reviewing the immunological and inflammatory responses associated with BBB damage secondary to tumoral activity, we identify the involvement of this pathological process in the growth and formation of metastatic brain cancers. Likewise, we evaluate the hypothesis of regenerating impaired endothelial cells of the BBB and alleviating the damaged neurovascular unit to attenuate brain metastasis, using the endothelial progenitor cell (EPC) phenotype of bone marrow-derived mesenchymal stem cells. Specifically, there is a need to evaluate the efficacy for stem cell therapy to repair disruptions in the BBB and reduce inflammation in the brain, thereby causing attenuation of metastatic brain cancers. To establish the viability of stem cell therapy for the prevention and treatment of metastatic brain tumors, it is crucial to demonstrate BBB repair through augmentation of vasculogenesis and angiogenesis. BBB disruption is strongly linked to metastatic melanoma, worsens neuroinflammation during metastasis, and negatively influences the prognosis of metastatic brain cancer. Using stem cell therapy to interrupt inflammation secondary to this leaky BBB represents a paradigm-shifting approach for brain cancer treatment. In this review article, we critically assess the advantages and disadvantages of using stem cell therapy for brain metastases and glioblastoma.

Combination of Stem Cells and Rehabilitation Therapies for Ischemic Stroke.

Stem cell transplantation with rehabilitation therapy presents an effective stroke treatment. Here, we discuss current breakthroughs in stem cell research along with rehabilitation strategies that may have a synergistic outcome when combined together after stroke. Indeed, stem cell transplantation offers a promising new approach and may add to current rehabilitation therapies. By reviewing the pathophysiology of stroke and the mechanisms by which stem cells and rehabilitation attenuate this inflammatory process, we hypothesize that a combined therapy will provide better functional outcomes for patients. Using current preclinical data, we explore the prominent types of stem cells, the existing theories for stem cell repair, rehabilitation treatments inside the brain, rehabilitation modalities outside the brain, and evidence pertaining to the benefits of combined therapy. In this review article, we assess the advantages and disadvantages of using stem cell transplantation with rehabilitation to mitigate the devastating effects of stroke.

IL-2/IL-2R Antibody Complex Enhances Treg-Induced Neuroprotection by Dampening TNF-α Inflammation in an In Vitro Stroke Model.

The present in vitro study showed that IL-2/IL-2R antibody complex facilitates Treg-induced neuroprotection in the oxygen glucose deprivation/reoxygenation (OGD/R) model of stroke. First, we examined the role of IL-2/IL-2R-treated Tregs in OGD/R-exposed rat primary cortical cells (PCCs), which represent the cell type of the ischemic gray matter in the stroke brain. Here, OGD/R induced cell death, which was attenuated by Tregs and more robustly by IL-2/IL-2R-treated Tregs, but not by IL-2/IL-2R treatment alone. Second, we next assessed IL-2/IL-2R effects in OGD/R-exposed human oligodendrocyte progenitor cells (OPCs), which correspond to the white matter injury after stroke. Results revealed that a similar pattern neuroprotection as seen in the gray matter, in that OGD/R triggered cell death, which was ameliorated by Tregs and more effectively by IL-2/IL-2R-treated Tregs, but IL-2/IL-2R treatment alone was not therapeutic. Third, as we begin to understand the mechanism underlying IL-2/IL-2R engagement of Tregs, we investigated the inflammatory response in OGD/R-exposed human neural progenitor cells (NPCs), which recapitulate both ischemic gray and white matter damage in stroke. Similar to PCCs and OPCs, OGD/R produced cell death and was blocked by Tregs and more efficiently by IL-2/IL-2R-treated Tregs, whereas IL-2/IL-2R treatment alone did not alter the ischemic insult. Moreover, the inflammatory marker, TNF-α, was upregulated after OGD/R, dampened by both Tregs and more efficiently by IL-2/IL-2R-treated Tregs but more pronounced in the latter, and not affected by IL-2/IL-2R treatment alone, suggesting IL-2/IL-2R-Treg-mediated modulation of inflammatory response in stroke. Altogether, these observations support the use of IL-2/IL-2R treatment in enhancing the anti-inflammatory effects of Tregs in stroke.