Enhancing Hematopoietic Stem Cell Transplantation Efficacy by Mitigating Oxygen Shock.

Hematopoietic stem cells (HSCs) reside in hypoxic niches within bone marrow and cord blood. Yet, essentially all HSC studies have been performed with cells isolated and processed in non-physiologic ambient air. By collecting and manipulating bone marrow and cord blood in native conditions of hypoxia, we demonstrate that brief exposure to ambient oxygen decreases recovery of long-term repopulating HSCs and increases progenitor cells, a phenomenon we term extraphysiologic oxygen shock/stress (EPHOSS). Thus, true numbers of HSCs in the bone marrow and cord blood are routinely underestimated. We linked ROS production and induction of the mitochondrial permeability transition pore (MPTP) via cyclophilin D and p53 as mechanisms of EPHOSS. The MPTP inhibitor cyclosporin A protects mouse bone marrow and human cord blood HSCs from EPHOSS during collection in air, resulting in increased recovery of transplantable HSCs. Mitigating EPHOSS during cell collection and processing by pharmacological means may be clinically advantageous for transplantation.

Relationship between Brain Metabolic Disorders and Cognitive Impairment: LDL Receptor Defect.

The low-density-lipoprotein receptor (LDLr) removes low-density lipoprotein (LDL), an endovascular transporter that carries cholesterol from the bloodstream to peripheral tissues. The maintenance of cholesterol content in the brain, which is important to protect brain function, is affected by LDLr. LDLr co-localizes with the insulin receptor and complements the internalization of LDL. In LDLr deficiency, LDL blood levels and insulin resistance increase, leading to abnormal cholesterol control and cognitive deficits in atherosclerosis. Defects in brain cholesterol metabolism lead to neuroinflammation and blood-brain-barrier (BBB) degradation. Moreover, interactions between endoplasmic reticulum stress (ER stress) and mitochondria are induced by ox-LDL accumulation, apolipoprotein E (ApoE) regulates the levels of amyloid beta (Aß) in the brain, and hypoxia is induced by apoptosis induced by the LDLr defect. This review summarizes the association between neurodegenerative brain disease and typical cognitive deficits.

Utility of Exosomes in Ischemic and Hemorrhagic Stroke Diagnosis and Treatment.

Stroke is the leading cause of death and neurological disorders worldwide. However, diagnostic techniques and treatments for stroke patients are still limited for certain types of stroke. Intensive research has been conducted so far to find suitable diagnostic techniques and treatments, but so far there has been no success. In recent years, various studies have drawn much attention to the clinical value of utilizing the mechanism of exosomes, low toxicity, biodegradability, and the ability to cross the blood-brain barrier. Recent studies have been reported on the use of biomarkers and protective and recovery effects of exosomes derived from stem cells or various cells in the diagnostic stage after stroke. This review focuses on publications describing changes in diagnostic biomarkers of exosomes following various strokes and processes for various potential applications as therapeutics.

Incidence, mortality, and cardiovascular diseases in pituitary adenoma in Korea: a nationwide population-based study.

PURPOSE: Few nationally representative studies have evaluated the epidemiology of PA (pituitary adenoma). This South Korean study evaluated the incidence of different PA subtypes, cardiovascular disease (CVD), and related mortality. METHODS: This population-based study evaluated 31,898 patients with PA during 2005-2015. The incidence of PA, mortality, and CVD occurrence in PA cases were evaluated during a median follow-up of 5.3 years (range: 0-10 years). Cox regression analysis was used to evaluate the associations between CVD and mortality. RESULTS: The annual incidences (per 100,000 population) were 3.5 for non-functioning pituitary adenoma (NFPA), 1.6 for prolactinoma (PRL), 0.5 for growth hormone-secreting pituitary adenoma (GH), and 0.2 for adrenocorticotropic or thyroid-stimulating hormone-secreting pituitary adenoma (ACTH + TSH). The standardized mortality ratios were 1.9 for ACTH + TSH, 1.7 for NFPA with hypopituitarism, 1.4 for NFPA without hypopituitarism, 1.3 for GH, and 1.1 for PRL. During 2005-2015, the overall incidence of CVD among PA patients was 6.6% (2106 cases), and the standardized incidence ratios were 4.1 for hemorrhagic stroke, 3.0 for ischemic stroke, and 1.7 for acute myocardial infarction. The standardized incidence ratios for stroke were significantly higher in the ACTH + TSH and NFPA groups, which also had higher risks of CVD-related mortality, relative to the PRL and GH groups. CONCLUSION: South Korea had a relatively high incidence of NFPA. The incidence of stroke was highest for ACTH + TSH and NFPA, which was directly related to mortality during long-term follow-up. Patients with these types of PA should receive stroke prevention measures to reduce their risk of mortality.

Short and Long-term Outcomes of Subarachnoid Hemorrhage Treatment according to Hospital Volume in Korea: a Nationwide Multicenter Registry.

BACKGROUND: Subarachnoid hemorrhage is a potentially devastating cerebrovascular attack with a high proportion of poor outcomes and mortality. Recent studies have reported decreased mortality with the improvement in devices and techniques for treating ruptured aneurysms and neurocritical care. This study investigated the relationship between hospital volume and short- and long-term mortality in patients treated with subarachnoid hemorrhage. METHODS: We selected subarachnoid hemorrhage patients treated with clipping and coiling from March-May 2013 to June-August 2014 using data from Acute Stroke Registry, and the selected subarachnoid hemorrhage (SAH) patients were tracked in connection with data of Health Insurance Review and Assessment Service to evaluate the short-term and long-term mortality. RESULTS: A total of 625 subarachnoid hemorrhage patients were admitted to high-volume hospitals (n = 355, 57%) and low-volume hospitals (n = 270, 43%) for six months. The mortality of SAH patients treated with clipping and coiling was 12.3%, 20.2%, 21.4%, and 24.3% at 14 days, three months, one year, and five years, respectively. The short-term and long-term mortality in high-volume hospitals was significantly lower than that in low-volume hospitals. On Cox regression analysis of death in patients with severe clinical status, low-volume hospitals had significantly higher mortality than high-volume hospitals during short-term follow-up. On Cox regression analysis in the mild clinical status group, there was no statistical difference between high-volume hospitals and low-volume hospitals. CONCLUSION: In subarachnoid hemorrhage patients treated with clipping and coiling, low-volume hospitals had higher short-term mortality than high-volume hospitals. These results from a nationwide database imply that acute SAH should be treated by a skilled neurosurgeon with adequate facilities in a high-volume hospital.

Single-Cell Transcriptome Analysis as a Promising Tool to Study Pluripotent Stem Cell Reprogramming.

Cells are the basic units of all organisms and are involved in all vital activities, such as proliferation, differentiation, senescence, and apoptosis. A human body consists of more than 30 trillion cells generated through repeated division and differentiation from a single-cell fertilized egg in a highly organized programmatic fashion. Since the recent formation of the Human Cell Atlas consortium, establishing the Human Cell Atlas at the single-cell level has been an ongoing activity with the goal of understanding the mechanisms underlying diseases and vital cellular activities at the level of the single cell. In particular, transcriptome analysis of embryonic stem cells at the single-cell level is of great importance, as these cells are responsible for determining cell fate. Here, we review single-cell analysis techniques that have been actively used in recent years, introduce the single-cell analysis studies currently in progress in pluripotent stem cells and reprogramming, and forecast future studies.

Generating autologous hematopoietic cells from human-induced pluripotent stem cells through ectopic expression of transcription factors.

PURPOSE OF REVIEW: Hematopoietic cell transplantation (HCT) is a successful treatment modality for patients with malignant and nonmalignant disorders, usually when no other treatment option is available. The cells supporting long-term reconstitution after HCT are the hematopoietic stem cells (HSCs), which can be limited in numbers. Moreover, finding an appropriate human leukocyte antigen-matched donor can be problematic. If HSCs can be stably produced in large numbers from autologous or allogeneic cell sources, it would benefit HCT. Induced pluripotent stem cells (iPSCs) established from patients' own somatic cells can be differentiated into hematopoietic cells in vitro. This review will highlight recent methods for regulating human (h) iPSC production of HSCs and more mature blood cells. RECENT FINDINGS: Advancements in transcription factor-mediated regulation of the developmental stages of in-vivo hematopoietic lineage commitment have begun to provide an understanding of the molecular mechanism of hematopoiesis. Such studies involve not only directed differentiation in which transcription factors, specifically expressed in hematopoietic lineage-specific cells, are overexpressed in iPSCs, but also direct conversion in which transcription factors are introduced into patient-derived somatic cells which are dedifferentiated to hematopoietic cells. As iPSCs derived from patients suffering from genetically mutated diseases would express the same mutated genetic information, CRISPR-Cas9 gene editing has been utilized to differentiate genetically corrected iPSCs into normal hematopoietic cells. SUMMARY: IPSCs provide a model for molecular understanding of disease, and also may function as a cell population for therapy. Efficient differentiation of patient-specific iPSCs into HSCs and progenitor cells is a potential means to overcome limitations of such cells for HCT, as well as for providing in-vitro drug screening templates as tissue-on-a-chip models.

Regulation of c-Myc Expression by Ahnak Promotes Induced Pluripotent Stem Cell Generation.

We have previously reported that Ahnak-mediated TGFß signaling leads to down-regulation of c-Myc expression. Here, we show that inhibition of Ahnak can promote generation of induced pluripotent stem cells (iPSC) via up-regulation of endogenous c-Myc. Consistent with the c-Myc inhibitory role of Ahnak, mouse embryonic fibroblasts from Ahnak-deficient mouse (Ahnak(-/-) MEF) show an increased level of c-Myc expression compared with wild type MEF. Generation of iPSC with just three of the four Yamanaka factors, Oct4, Sox2, and Klf4 (hereafter 3F), was significantly enhanced in Ahnak(-/-) MEF. Similar results were obtained when Ahnak-specific shRNA was applied to wild type MEF. Of note, expressionof Ahnak was significantly induced during the formation of embryoid bodies from embryonic stem cells, suggesting that Ahnak-mediated c-Myc inhibition is involved in embryoid body formation and the initial differentiation of pluripotent stem cells. The iPSC from 3F-infected Ahnak(-/-) MEF cells (Ahnak(-/-)-iPSC-3F) showed expression of all stem cell markers examined and the capability to form three primary germ layers. Moreover, injection of Ahnak(-/-)-iPSC-3F into athymic nude mice led to development of teratoma containing tissues from all three primary germ layers, indicating that iPSC from Ahnak(-/-) MEF are bona fide pluripotent stem cells. Taken together, these data provide evidence for a new role for Ahnak in cell fate determination during development and suggest that manipulation of Ahnak and the associated signaling pathway may provide a means to regulate iPSC generation.

SIRT1 positively regulates autophagy and mitochondria function in embryonic stem cells under oxidative stress.

SIRT1, an NAD-dependent deacetylase, plays a role in regulation of autophagy. SIRT1 increases mitochondrial function and reduces oxidative stress, and has been linked to age-related reactive oxygen species (ROS) generation, which is highly dependent on mitochondrial metabolism. H2O2 induces oxidative stress and autophagic cell death through interference with Beclin 1 and the mTOR signaling pathways. We evaluated connections between SIRT1 activity and induction of autophagy in murine (m) and human (h) embryonic stem cells (ESCs) upon ROS challenge. Exogenous H2 O2 (1 mM) induced apoptosis and autophagy in wild-type (WT) and Sirt1-/- mESCs. High concentrations of H2O2 (1 mM) induced more apoptosis in Sirt1-/-, than in WT mESCs. However, addition of 3-methyladenine, a widely used autophagy inhibitor, in combination with H2O2 induced more cell death in WT than in Sirt1-/- mESCs. Decreased induction of autophagy in Sirt1-/- mESCs was demonstrated by decreased conversion of LC3-I to LC3-II, lowered expression of Beclin-1, and decreased LC3 punctae and LysoTracker staining. H2O2 induced autophagy with loss of mitochondrial membrane potential and disruption of mitochondrial dynamics in Sirt1-/- mESCs. Increased phosphorylation of P70/85-S6 kinase and ribosomal S6 was noted in Sirt1-/- mESCs, suggesting that SIRT1 regulates the mTOR pathway. Consistent with effects in mESCs, inhibition of SIRT1 using Lentivirus-mediated SIRT1 shRNA in hESCs demonstrated that knockdown of SIRT1 decreased H2O2-induced autophagy. This suggests a role for SIRT1 in regulating autophagy and mitochondria function in ESCs upon oxidative stress, effects mediated at least in part by the class III PI3K/Beclin 1 and mTOR pathways.

Epigenetic regulation of NANOG by miR-302 cluster-MBD2 completes induced pluripotent stem cell reprogramming.

While most somatic cells undergoing induced pluripotent stem (iPS) cell reprogramming with Yamanaka factors accumulate at stable partially reprogrammed stages, the molecular mechanisms required to achieve full reprogramming are unknown. MicroRNAs (miRNAs) fine-tune mRNA translation and are implicated in reprogramming, but miRNA functional targets critical for complete iPS cell reprogramming remain elusive. We identified methyl-DNA binding domain protein 2 (MBD2) as an epigenetic suppressor, blocking full reprogramming of somatic to iPS cells through direct binding to NANOG promoter elements preventing transcriptional activation. When we overexpressed miR-302 cluster we observed a significant increase in conversion of partial to fully reprogrammed iPS cells by suppressing MBD2 expression, thereby increasing NANOG expression. Thus, expression of exogenous miR-302 cluster (without miR-367) is efficient in attaining a fully reprogrammed iPS state in partially reprogrammed cells by relieving MBD2-mediated inhibition of NANOG expression. Our studies provide a direct molecular mechanism involved in generating complete human iPS cell reprogramming to study disease pathogenesis, drug screening, and for potential cell-based therapies.

Neuronal Cell Differentiation of iPSCs for the Clinical Treatment of Neurological Diseases.

Current chemical treatments for cerebrovascular disease and neurological disorders have limited efficacy in tissue repair and functional restoration. Induced pluripotent stem cells (iPSCs) present a promising avenue in regenerative medicine for addressing neurological conditions. iPSCs, which are capable of reprogramming adult cells to regain pluripotency, offer the potential for patient-specific, personalized therapies. The modulation of molecular mechanisms through specific growth factor inhibition and signaling pathways can direct iPSCs' differentiation into neural stem cells (NSCs). These include employing bone morphogenetic protein-4 (BMP-4), transforming growth factor-beta (TGFß), and Sma-and Mad-related protein (SMAD) signaling. iPSC-derived NSCs can subsequently differentiate into various neuron types, each performing distinct functions. Cell transplantation underscores the potential of iPSC-derived NSCs to treat neurodegenerative diseases such as Parkinson's disease and points to future research directions for optimizing differentiation protocols and enhancing clinical applications.

Energy Metabolism in Human Pluripotent Stem and Differentiated Cells Compared Using a Seahorse XF96 Extracellular Flux Analyzer.

Evaluating cell metabolism is crucial during pluripotent stem cell (PSC) differentiation and somatic cell reprogramming as it affects cell fate. As cultured stem cells are heterogeneous, a comparative analysis of relative metabolism using existing metabolic analysis methods is difficult, resulting in inaccuracies. In this study, we measured human PSC basal metabolic levels using a Seahorse analyzer. We used fibroblasts, human induced PSCs, and human embryonic stem cells to monitor changes in basal metabolic levels according to cell number and determine the number of cells suitable for analysis. We evaluated normalization methods using glucose and selected the most suitable for the metabolic analysis of heterogeneous PSCs during the reprogramming stage. The response of fibroblasts to glucose increased with starvation time, with oxygen consumption rate and extracellular acidification rate responding most effectively to glucose 4 hours after starvation and declining after 5 hours of starvation. Fibroblasts and PSCs achieved appropriate responses to glucose without damaging their metabolism 2∼4 and 2∼3 hours after starvation, respectively. We developed a novel method for comparing basal metabolic rates of fibroblasts and PSCs, focusing on quantitative analysis of glycolysis and oxidative phosphorylation using glucose without enzyme inhibitors. This protocol enables efficient comparison of energy metabolism among cell types, including undifferentiated PSCs, differentiated cells, and cells undergoing cellular reprogramming, and addresses critical issues, such as differences in basal metabolic levels and sensitivity to normalization, providing valuable insights into cellular energetics.

Hematopoietic stem/progenitor cells, generation of induced pluripotent stem cells, and isolation of endothelial progenitors from 21- to 23.5-year cryopreserved cord blood.

Cryopreservation of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) is crucial for cord blood (CB) banking and transplantation. We evaluated recovery of functional HPC cryopreserved as mononuclear or unseparated cells for up to 23.5 years compared with prefreeze values of the same CB units. Highly efficient recovery (80%-100%) was apparent for granulocyte-macrophage and multipotential hematopoietic progenitors, although some collections had reproducible low recovery. Proliferative potential, response to multiple cytokines, and replating of HPC colonies was extensive. CD34(+) cells isolated from CB cryopreserved for up to 21 years had long-term (≥ 6 month) engrafting capability in primary and secondary immunodeficient mice reflecting recovery of long-term repopulating, self-renewing HSCs. We recovered functionally responsive CD4(+) and CD8(+) T lymphocytes, generated induced pluripotent stem (iPS) cells with differentiation representing all 3 germ cell lineages in vitro and in vivo, and detected high proliferative endothelial colony forming cells, results of relevance to CB biology and banking.

5-Aminoimidazole-4-carboxyamide ribonucleoside induces G(1)/S arrest and Nanog downregulation via p53 and enhances erythroid differentiation.

Molecular mechanisms of how energy metabolism affects embryonic stem cell (ESC) pluripotency remain unclear. AMP-activated protein kinase (AMPK), a key regulator for controlling energy metabolism, is activated in response to ATP-exhausting stress. We investigated whether cellular energy homeostasis is associated with maintenance of self-renewal and pluripotency in mouse ESCs (mESCs) by using 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR) as an activator of AMPK. We demonstrate that AICAR treatment activates the p53/p21 pathway and markedly inhibits proliferation of R1 mESCs by inducing G(1) /S-phase cell cycle arrest, without influencing apoptosis. Treatment with AICAR also significantly reduces pluripotent stem cell markers, Nanog and stage-specific embryonic antigen-1, in the presence of leukemia inhibitory factor, without affecting expression of Oct4. H9 human ESCs also responded to AICAR with induction of p53 activation and repression of Nanog expression. AICAR reduced Nanog mRNA levels in mESCs transiently, an effect not due to expression of miR-134 which can suppress Nanog expression. AICAR induced Nanog degradation, an effect inhibited by MG132, a proteasome inhibitor. Although AICAR reduced embryoid body formation from mESCs, it increased expression levels of erythroid cell lineage markers (Ter119, GATA1, Klf1, Hbb-b, and Hbb-bh1). Although erythroid differentiation was enhanced by AICAR, endothelial lineage populations were remarkably reduced in AICAR-treated cells. Our results suggest that energy metabolism regulated by AMPK activity may control the balance of self-renewal and differentiation of ESCs.

Albumin-binding photosensitizer capable of targeting glioma via the SPARC pathway.

BACKGROUND: Malignant glioma is among the most lethal and frequently occurring brain tumors, and the average survival period is 15 months. Existing chemotherapy has low tolerance and low blood-brain barrier (BBB) permeability; therefore, the required drug dose cannot be accurately delivered to the tumor site, resulting in an insufficient drug effect. METHODS: Herein, we demonstrate a precision photodynamic tumor therapy using a photosensitizer (ZnPcS) capable of binding to albumin in situ, which can increase the permeability of the BBB and accurately target glioma. Albumin-binding ZnPcS was designed to pass through the BBB and bind to secreted protein acidic and rich in cysteine (SPARC), which is abundant in the glioma plasma membrane. RESULTS: When the upper part of a mouse brain was irradiated using a laser (0.2 W cm- 2) after transplantation of glioma and injection of ZnPcS, tumor growth was inhibited by approximately 83.6%, and the 50% survival rate of the treatment group increased by 14 days compared to the control group. In glioma with knockout SPARC, the amount of ZnPcS entering the glioma was reduced by 63.1%, indicating that it can target glioma through the SPARC pathway. CONCLUSION: This study showed that the use of albumin-binding photosensitizers is promising for the treatment of malignant gliomas.

Cyclic Stretch Promotes Cellular Reprogramming Process through Cytoskeletal-Nuclear Mechano-Coupling and Epigenetic Modification.

Advancing the technologies for cellular reprogramming with high efficiency has significant impact on regenerative therapy, disease modeling, and drug discovery. Biophysical cues can tune the cell fate, yet the precise role of external physical forces during reprogramming remains elusive. Here the authors show that temporal cyclic-stretching of fibroblasts significantly enhances the efficiency of induced pluripotent stem cell (iPSC) production. Generated iPSCs are proven to express pluripotency markers and exhibit in vivo functionality. Bulk RNA-sequencing reveales that cyclic-stretching enhances biological characteristics required for pluripotency acquisition, including increased cell division and mesenchymal-epithelial transition. Of note, cyclic-stretching activates key mechanosensitive molecules (integrins, perinuclear actins, nesprin-2, and YAP), across the cytoskeletal-to-nuclear space. Furthermore, stretch-mediated cytoskeletal-nuclear mechano-coupling leads to altered epigenetic modifications, mainly downregulation in H3K9 methylation, and its global gene occupancy change, as revealed by genome-wide ChIP-sequencing and pharmacological inhibition tests. Single cell RNA-sequencing further identifies subcluster of mechano-responsive iPSCs and key epigenetic modifier in stretched cells. Collectively, cyclic-stretching activates iPSC reprogramming through mechanotransduction process and epigenetic changes accompanied by altered occupancy of mechanosensitive genes. This study highlights the strong link between external physical forces with subsequent mechanotransduction process and the epigenetic changes with expression of related genes in cellular reprogramming, holding substantial implications in the field of cell biology, tissue engineering, and regenerative medicine.

Neuroinflammation in Post-Traumatic Stress Disorder.

Post-traumatic stress disorder (PTSD) is a well-known mental illness, which is caused by various stressors, including memories of past physical assaults and psychological pressure. It is diagnosed as a mental and behavioral disorder, but increasing evidence is linking it to the immune system and inflammatory response. Studies on the relationship between inflammation and PTSD revealed that patients with PTSD had increased levels of inflammatory cytokine biomarkers, such as interleukin-1, interleukin-6, tumor necrosis factor-α, nuclear factor-κB, and C-reactive protein, compared with healthy controls. In addition, animal model experiments imitating PTSD patients suggested the role of inflammation in the pathogenesis and pathophysiology of PTSD. In this review, we summarize the definition of PTSD and its association with increased inflammation, its mechanisms, and future predictable diseases and treatment possibilities. We also discuss anti-inflammatory treatments to address inflammation in PTSD.

Phosphodiesterase-5 Inhibitor Attenuates Anxious Phenotypes and Movement Disorder Induced by Mild Ischemic Stroke in Rats.

OBJECTIVE: Patients with mild ischemic stroke experience various sequela and residual symptoms, such as anxious behavior and deficits in movement. Few approaches have been proved to be effective and safe therapeutic approaches for patients with mild ischemic stroke by acute stroke. Sildenafil (SIL), a phosphodiesterase-5 inhibitor (PDE5i), is a known remedy for neurodegenerative disorders and vascular dementia through its angiogenesis and neurogenesis effects. In this study, we investigated the efficacy of PDE5i in the emotional and behavioral abnormalities in rats with mild ischemic stroke. METHODS: We divided the rats into four groups as follows (n=20, respectively) : group 1, naïve; group 2, middle cerebral artery occlusion (MCAo30); group 3, MCAo30+SIL-pre; and group 4, MCAo30+SIL-post. In the case of drug administration groups, single dose of PDE5i (sildenafil citrate, 20 mg/kg) was given at 30-minute before and after reperfusion of MCAo in rats. After surgery, we investigated and confirmed the therapeutic effect of sildenafil on histology, immunofluorescence, behavioral assays and neural oscillations. RESULTS: Sildenafil alleviated a neuronal loss and reduced the infarction volume. And results of behavior task and immunofluorescence shown possibility that anti-inflammation process and improve motor deficits sildenafil treatment after mild ischemic stroke. Furthermore, sildenafil treatment attenuated the alteration of theta-frequency rhythm in the CA1 region of the hippocampus, a known neural oscillatory marker for anxiety disorder in rodents, induced by mild ischemic stroke. CONCLUSION: PDE5i as effective therapeutic agents for anxiety and movement disorders and provide robust preclinical evidence to support the development and use of PDE5i for the treatment of mild ischemic stroke residual disorders.

ROCK and PDE-5 Inhibitors for the Treatment of Dementia: Literature Review and Meta-Analysis.

Dementia is a disease in which memory, thought, and behavior-related disorders progress gradually due to brain damage caused by injury or disease. It is mainly caused by Alzheimer's disease or vascular dementia and several other risk factors, including genetic factors. It is difficult to treat as its incidence continues to increase worldwide. Many studies have been performed concerning the treatment of this condition. Rho-associated kinase (ROCK) and phosphodiesterase-5 (PDE-5) are attracting attention as pharmacological treatments to improve the symptoms. This review discusses how ROCK and PDE-5 affect Alzheimer's disease, vascular restructuring, and exacerbation of neuroinflammation, and how their inhibition helps improve cognitive function. In addition, the results of the animal behavior analysis experiments utilizing the Morris water maze were compared through meta-analysis to analyze the effects of ROCK inhibitors and PDE-5 inhibitors on cognitive function. According to the selection criteria, 997 publications on ROCK and 1772 publications on PDE-5 were screened, and conclusions were drawn through meta-analysis. Both inhibitors showed good improvement in cognitive function tests, and what is expected of the synergy effect of the two drugs was confirmed in this review.

Inflammation and Rho-Associated Protein Kinase-Induced Brain Changes in Vascular Dementia.

Patients with vascular dementia, caused by cerebral ischemia, experience long-term cognitive impairment due to the lack of effective treatment. The mechanisms of and treatments for vascular dementia have been investigated in various animal models; however, the insufficient information on gene expression changes that define pathological conditions hampers progress. To investigate the underlying mechanism of and facilitate treatment development for vascular dementia, we established a mouse model of chronic cerebral hypoperfusion, including bilateral carotid artery stenosis, by using microcoils, and elucidated the molecular pathway underlying vascular dementia development. Rho-associated protein kinase (ROCK) 1/2, which regulates cellular structure, and inflammatory cytokines (IL-1 and IL-6) were upregulated in the vascular dementia model. However, expression of claudin-5, which maintains the blood-brain barrier, and MAP2 as a nerve cell-specific factor, was decreased in the hippocampal region of the vascular dementia model. Thus, we revealed that ROCK pathway activation loosens the tight junction of the blood-brain barrier and increases the influx of inflammatory cytokines into the hippocampal region, leading to neuronal death and causing cognitive and emotional dysfunction. Our vascular dementia model allows effective study of the vascular dementia mechanism. Moreover, the ROCK pathway may be a target for vascular dementia treatment development in the future.