Advances in the differentiation of pluripotent stem cells into vascular cells.

Blood vessels constitute a closed pipe system distributed throughout the body, transporting blood from the heart to other organs and delivering metabolic waste products back to the lungs and kidneys. Changes in blood vessels are related to many disorders like stroke, myocardial infarction, aneurysm, and diabetes, which are important causes of death worldwide. Translational research for new approaches to disease modeling and effective treatment is needed due to the huge socio-economic burden on healthcare systems. Although mice or rats have been widely used, applying data from animal studies to human-specific vascular physiology and pathology is difficult. The rise of induced pluripotent stem cells (iPSCs) provides a reliable in vitro resource for disease modeling, regenerative medicine, and drug discovery because they carry all human genetic information and have the ability to directionally differentiate into any type of human cells. This review summarizes the latest progress from the establishment of iPSCs, the strategies for differentiating iPSCs into vascular cells, and the in vivo transplantation of these vascular derivatives. It also introduces the application of these technologies in disease modeling, drug screening, and regenerative medicine. Additionally, the application of high-tech tools, such as omics analysis and high-throughput sequencing, in this field is reviewed.

Loss of function of CMPK2 causes mitochondria deficiency and brain calcification.

Brain calcification is a critical aging-associated pathology and can cause multifaceted neurological symptoms. Cerebral phosphate homeostasis dysregulation, blood-brain barrier defects, and immune dysregulation have been implicated as major pathological processes in familial brain calcification (FBC). Here, we analyzed two brain calcification families and identified calcification co-segregated biallelic variants in the CMPK2 gene that disrupt mitochondrial functions. Transcriptome analysis of peripheral blood mononuclear cells (PBMCs) isolated from these patients showed impaired mitochondria-associated metabolism pathways. In situ hybridization and single-cell RNA sequencing revealed robust Cmpk2 expression in neurons and vascular endothelial cells (vECs), two cell types with high energy expenditure in the brain. The neurons in Cmpk2-knockout (KO) mice have fewer mitochondrial DNA copies, down-regulated mitochondrial proteins, reduced ATP production, and elevated intracellular inorganic phosphate (Pi) level, recapitulating the mitochondrial dysfunction observed in the PBMCs isolated from the FBC patients. Morphologically, the cristae architecture of the Cmpk2-KO murine neurons was also impaired. Notably, calcification developed in a progressive manner in the homozygous Cmpk2-KO mice thalamus region as well as in the Cmpk2-knock-in mice bearing the patient mutation, thus phenocopying the calcification pathology observed in the patients. Together, our study identifies biallelic variants of CMPK2 as novel genetic factors for FBC; and demonstrates how CMPK2 deficiency alters mitochondrial structures and functions, thereby highlighting the mitochondria dysregulation as a critical pathogenic mechanism underlying brain calcification.

Optimization of the cut-offs in acetylcholine receptor antibodies and diagnostic performance in myasthenia gravis patients.

OBJECTIVE: This study aims to establish an optimization procedure to define the cut-offs of quantitative assays for acetylcholine receptor antibody (AChRAb), evaluate their diagnostic performance in myasthenia gravis (MG), and explore the association with clinical features. METHODS: Samples from a representative cohort of 77 MG patients, 80 healthy controls (HC) and 80 other autoimmune diseases (OAD) patients were tested using competitive inhibition ELISA and RIA. Raw values (OD and cpm) and processed values (inhibition rate, binding rate and concentration) were used to define the cut-offs with statistical methods, a rough method, and receiver operating characteristic (ROC) curve. Optimal cut-offs were selected by comparing false positive rates in HC and OAD individuals. The diagnostic performance was evaluated in whole MG cohort and subgroups. Agreement between ELISA and RIA for AChRAb positivity were examined with Kappa test and McNemar test. Clinical association with AChRAb was explored by comparison among subgroups and with Spearman rank correlation. RESULTS: The optimal cut-offs for AChRAb positivity were determined as OD ≤ 1.79 for ELISA and cpm ≥ 1234.12 for RIA, which derived from statistical method and performed better than those derived from ROC curves. The sensitivity and specificity were 74.03%, 100% for ELISA, and 74.03%, 99.37% for RIA. There was good agreement between ELISA and RIA for AChRAb positivity in whole cohort and subgroups (weighted к ≥ 0.71, p < 0.01; McNemar test, p > 0.05). Levels of AChRAb were different in MG subgroups (p < 0.01). Correlation between Quantitative Myasthenia Gravis scores and AChRAb levels was moderate for ELISA and RIA (rs = -0.60 and 0.57, p < 0.01). CONCLUSION: The raw testing values of ELISA and RIA were found as optimal quantitative measures of AChRAb levels. There are good agreements on diagnostic performance between two assays. Quantitative values are more informative than positivity in association with clinical features.

Clinical, genetic, and pathological characterization of GNE myopathy in China.

BACKGROUND: GNE myopathy is the most common distal myopathy in China. We summarized the clinical, genetic, and pathological characteristics of 125 Chinese patients with GNE myopathy. METHODS: We collected clinical data of 21 patients diagnosed at our hospital and 104 patients from previous reports. Clinical, genetic, and pathological characteristics were summarized. According to the location of mutations, patients were classified into groups to analyze genotype-phenotype correlation. We reviewed the pathological features and studied the expressions of neural cell adhesion molecule. RESULTS: The severity of involvement of lower limb muscles was in the following order: tibialis anterior > biceps femoris > gastrocnemius > iliopsoas > quadriceps femoris. Mutation p.D207V was the most common variant in China. Patients carrying p.D207V tended to show later disease onset. In the epimerase/epimerase group, men had earlier disease onset than women (p < 0.05). In other groups, age at disease onset in females was earlier than that in males. Protein analysis showed decreased sialylation of NCAM and upregulation of LC3 in patients with different mutations. CONCLUSIONS: Mutation p.D207V is the most common GNE variant in China. Involvement of flexor muscles in lower limbs was more obvious than extensor muscles. NCAM expression in patients with various mutations may be a useful diagnostic biomarker in GNE myopathy.

A heterozygous deletion of PDGFB gene causes paroxysmal kinesigenic dyskinesia with primary familial brain calcification.

BACKGROUND: Primary familial brain calcification (PFBC) is a neurodegenerative disease characterized with calcium deposition in multiple brain regions. Mutations in PDGFB have been discovered in sporadic and familial PFBC cases. While several known variants displayed loss-of function, no complete deletion of platelet-derived growth factor B (PDGFB) has been reported. METHODS: For the diagnostic purpose, brain computerized tomography or magnetic resonance imaging scanning and whole-genome sequencing were performed on the proband and family members in the pedigree. RESULTS: We identified a heterozygous PDGFB complete deletion in a Chinese pedigree. The proband presented with paroxysmal kinesigenic dyskinesia (PKD), a rare symptom in PFBC. The proband's mother carrying the same mutation was asymptomatic. CONCLUSIONS: For the first time, we reported a PFBC with a heterozygous deletion of PDGFB, and provided evidence of haploinsufficiency in the pathogenesis of PFBC.

Smek1 deficiency exacerbates experimental autoimmune encephalomyelitis by activating proinflammatory microglia and suppressing the IDO1-AhR pathway.

BACKGROUND: Experimental autoimmune encephalomyelitis (EAE) is an animal disease model of multiple sclerosis (MS) that involves the immune system and central nervous system (CNS). However, it is unclear how genetic predispositions promote neuroinflammation in MS and EAE. Here, we investigated how partial loss-of-function of suppressor of MEK1 (SMEK1), a regulatory subunit of protein phosphatase 4, facilitates the onset of MS and EAE. METHODS: C57BL/6 mice were immunized with myelin oligodendrocyte glycoprotein 35-55 (MOG35-55) to establish the EAE model. Clinical signs were recorded and pathogenesis was investigated after immunization. CNS tissues were analyzed by immunostaining, quantitative polymerase chain reaction (qPCR), western blot analysis, and enzyme-linked immunosorbent assay (ELISA). Single-cell analysis was carried out in the cortices and hippocampus. Splenic and lymph node cells were evaluated with flow cytometry, qPCR, and western blot analysis. RESULTS: Here, we showed that partial Smek1 deficiency caused more severe symptoms in the EAE model than in controls by activating myeloid cells and that Smek1 was required for maintaining immunosuppressive function by modulating the indoleamine 2,3-dioxygenase (IDO1)-aryl hydrocarbon receptor (AhR) pathway. Single-cell sequencing and an in vitro study showed that Smek1-deficient microglia and macrophages were preactivated at steady state. After MOG35-55 immunization, microglia and macrophages underwent hyperactivation and produced increased IL-1ß in Smek1-/+ mice at the peak stage. Moreover, dysfunction of the IDO1-AhR pathway resulted from the reduction of interferon γ (IFN-γ), enhanced antigen presentation ability, and inhibition of anti-inflammatory processes in Smek1-/+ EAE mice. CONCLUSIONS: The present study suggests a protective role of Smek1 in autoimmune demyelination pathogenesis via immune suppression and inflammation regulation in both the immune system and the central nervous system. Our findings provide an instructive basis for the roles of Smek1 in EAE and broaden the understanding of the genetic factors involved in the pathogenesis of autoimmune demyelination.

Motor Symptom Lateralization Influences Cortico-Striatal Functional Connectivity in Parkinson's Disease.

Objective: The striatum is unevenly impaired bilaterally in Parkinson's disease (PD). Because the striatum plays a key role in cortico-striatal circuits, we assume that lateralization affects cortico-striatal functional connectivity in PD. The present study sought to evaluate the effect of lateralization on various cortico-striatal circuits through resting-state functional magnetic resonance imaging (fMRI). Methods: Thirty left-onset Parkinson's disease (LPD) patients, 27 right-onset Parkinson's disease (RPD) patients, and 32 normal controls with satisfactory data were recruited. Their demographic, clinical, and neuropsychological information was collected. Resting-state fMRI was performed, and functional connectivity changes of seven subdivisions of the striatum were explored in the two PD groups. In addition, the associations between altered functional connectivity and various clinical and neuropsychological characteristics were analyzed by Pearson's or Spearman's correlation. Results: Directly comparing the LPD and RPD patients demonstrated that the LPD patients had lower FC between the left dorsal rostral putamen and the left orbitofrontal cortex than the RPD patients. In addition, the LPD patients showed aberrant functional connectivity involving several striatal subdivisions in the right hemisphere. The right dorsal caudate, ventral rostral putamen, and superior ventral striatum had decreased functional connectivity with the cerebellum and parietal and occipital lobes relative to the normal control group. The comparison between RPD patients and the controls did not obtain significant difference in functional connectivity. The functional connectivity between the left dorsal rostral putamen and the left orbitofrontal cortex was associated with contralateral motor symptom severity in PD patients. Conclusions: Our findings provide new insights into the distinct characteristics of cortico-striatal circuits in LPD and RPD patients. Lateralization of motor symptoms is associated with lateralized striatal functional connectivity.

Abnormal Spontaneous Brain Activity in Left-Onset Parkinson Disease: A Resting-State Functional MRI Study.

Objective: Motor asymmetry is characteristic in Parkinson disease (PD). This phenomenon is originated from uneven degeneration of bilateral substantia nigra. However, this asymmetry may not restrict to substantia nigra or striatum. We aimed to determine the effect of asymmetry on spontaneous brain activity across the whole brain. Methods: We consecutively recruited 71 patients with PD, as well as 35 healthy controls, and collected relevant demographic, clinical, and neuropsychological information. The PD patients were divided into two groups according to the side of motor symptom onset. All the participants underwent resting-state functional magnetic resonance imaging, and spontaneous brain activity was assessed using amplitude of low-frequency fluctuation (ALFF). The associations between areas showing significant group differences and various clinical and neuropsychological measures were analyzed. Results: Finally, the data of 30 PD patients with left-onset (LPD), 27 PD patients with right-onset (RPD), and 32 healthy controls were obtained. The three groups had similar age and gender ratios. Our results demonstrated that LPD patients had increased ALFF in the left inferior temporal gyrus and decreased ALFF in bilateral thalamus and cerebellum anterior lobes than the control group. The value of ALFF of the left inferior temporal gyrus was correlated with motor function, and ALFF value of the thalamus was associated with cognition. Comparisons between LPD and RPD patients and between RPD patients and the controls did not yield significant difference. Conclusions: The present study provides new insights into the distinct characteristics of spontaneous brain activity in LPD, which may be associated with motor and cognitive function.

Cervical Spinal Involvement in a Chinese Pedigree With Pontine Autosomal Dominant Microangiopathy and Leukoencephalopathy Caused by a 3' Untranslated Region Mutation of COL4A1 Gene.

Background and Purpose- Pontine autosomal dominant microangiopathy and leukoencephalopathy, a recently defined subtype of cerebral small vessel disease, is associated with mutations in COL4A1 (collagen type IV alpha 1 chain) 3' untranslated region. We here describe a pontine autosomal dominant microangiopathy and leukoencephalopathy pedigree with COL4A1 mutation presenting both pontine and cervical spinal cord involvement. Methods- For the diagnostic purpose, brain and spinal magnetic resonance imaging scanning, skin biopsy, and whole-exome sequencing were performed on the patients in the pedigree. Suspected pathogenic variants were further confirmed by cosegregation analysis using Sanger sequencing in the family members. Results- We identified a mutation located at the binding site of miR-29 (microRNA-29) in 3' untranslated region of COL4A1(c.*32G>A). The pontine autosomal dominant microangiopathy and leukoencephalopathy patients in this pedigree carried this variant, whereas other healthy family members but one did not. Magnetic resonance imaging showed lesions in the pons, white matter, and cervical spinal cord. Skin biopsy revealed thickened basal lamina in vessels. Conclusions- For the first time, we reported cervical spinal involvement in pontine autosomal dominant microangiopathy and leukoencephalopathy and expanded the clinical spectrum of this disease.

Activated mTOR signaling pathway in myofibers with inherited metabolic defect might be an evidence for mTOR inhibition therapies.

BACKGROUND: Abnormally activated mechanistic target of rapamycin (mTOR) pathway has been reported in several model animals with inherited metabolic myopathies (IMMs). However, the profiles of mTOR pathway in skeletal muscles from patients are still unknown. This study aimed to analyze the activity of mTOR pathway in IMMs muscles. METHODS: We collected muscle samples from 25 patients with mitochondrial myopathy (MM), lipid storage disease (LSD) or Pompe disease (PD). To evaluate the activity of mTOR pathway in muscle specimens, phosphorylation of S6 ribosomal protein (p-S6) and p70S6 kinase (p-p70S6K) were analyzed by Western blotting and immunohistochemistry. RESULTS: Western blotting results showed that p-p70S6K/p70S6K in muscles from LSD and MM was up-regulated when compared with normal controls (NC) (NC vs. LSD, U = 2.000, P = 0.024; NC vs. MM: U = 6.000, P = 0.043). Likewise, p-S6/S6 was also up-regulated in muscles from all three subgroups of IMMs (NC vs. LSD, U = 0.000, P = 0.006; NC vs. PD, U = 0.000, P = 0.006; NC vs. MM, U = 1.000, P = 0.007). Immunohistochemical study revealed that p-S6 was mainly expressed in fibers with metabolic defect. In MM muscles, most p-S6 positive fibers showed cytochrome C oxidase (COX) deficiency (U = 5.000, P = 0.001). In LSD and PD muscles, p-S6 was mainly overexpressed in fibers with intramuscular vacuoles containing lipid droplets (U = 0.000, P = 0.002) or basophilic materials (U = 0.000, P = 0.002). CONCLUSION: The mTOR pathway might be activated in myofibers with various metabolic defects, which might provide evidence for mTOR inhibition therapy in human IMMs.

Clinical feature and outcome of late-onset cobalamin C disease patients with neuropsychiatric presentations: a Chinese case series.

OBJECTIVE: The Cobalamin C (cblC) disease is an inborn error of cobalamin metabolism. Late-onset cblC disease was diagnosed in patients having overt symptoms after 4 years of age. The late-onset cblC disease patients were rare and easily misdiagnosed. This study analyzed the clinical presentations, gene mutations, and treatments of Chinese patients with late-onset cblC disease. METHODS: The clinical data of 26 Han Chinese patients diagnosed with late-onset cblC disease were retrospectively analyzed. All patients underwent serum homocysteine level exam, urine concentrations of organic acids measurement, neuroimaging scans, gene analysis, and treatments evaluations. RESULTS: The mean age at disease onset and diagnosis was 17.8±7.0 years. The most frequent neuropsychiatric disturbances were lower limb weakness (50%), psychiatric disturbances (46.2%), and gait instability (42.3%). The mean methylmalonic acid level in urine was 107.4±56.6 µmol/L, and mean serum total homocysteine was 105.4±41.0 µmol/L. The most common abnormal radioimaging changes were observed in the spinal cord (88%) and brain (32%). Scoliosis was detected in 85.7% of patients. The methylmalonic aciduria and homocystinuria type C protein gene analysis showed that c.482G>A (57.7%) and c.609G>A (34.6%) mutations were the most frequent genotypes. After treatments with hydroxycobalamin, betaine, folic acid, L-carnitine, and compound vitamin B, the clinical features and biochemical parameters of patients with late-onset cblC disease were found to be alleviated. CONCLUSION: In our late-onset cblC disease cases, lower limb weakness, psychiatric disturbances, and gait instability were the most frequent manifestations. Patients responded well to the drug treatments with hydrocobalamin and betaine. When juvenile or adult patients with hyperhomocysteinemia present with neurological symptoms, cblC disease needs to be considered.

Clinical, Neuroimaging, and Pathological Analyses of 13 Chinese Leigh Syndrome Patients with Mitochondrial DNA Mutations.

BACKGROUND: Leigh syndrome (LS) is a rare disease caused by mitochondrial defects and has high phenotypic and genotypic heterogeneity. We analyzed the clinical symptoms, neuroimaging, muscular histopathology, and genotypes of 13 Chinese LS patients with mitochondrial DNA (mtDNA) mutations. METHODS: Mutations in mtDNA were identified by targeted sequencing. The brain imaging features on magnetic resonance imaging (MRI) were analyzed. The levels of lactate in fasting blood and cerebrospinal fluid (CSF) were routinely tested. The levels of urinary organic acids, plasma amino acids, and acylcarnitines were examined with gas chromatography-mass spectrometry and tandem mass spectrometry. The histopathological traits of skeletal muscles were analyzed under microscope. RESULTS: Among 13 patients, mutations of MT-NDs (n = 8) and MT-ATP6 (n = 4) genes were most common. Strabismus (8/13), muscle weakness (8/13), and ataxia (5/13) were also common, especially for the patients with late-onset age after 2 years old. However, respiratory distress was common in patients with early-onset age before 2 years old. The most frequently affected brain area in these patients was the brain stem (12/13), particularly the dorsal part of midbrain, followed by basal ganglia (6/13), thalamus (6/13), cerebellum (5/13), and supratentorial white matter (2/13). Besides, the elevated lactate levels in CSF (6/6) were more common than those in serum (7/13). However, the analysis of abnormal plasma amino acid and urinary organic acid showed limited results (0/3 and 1/4, respectively). Muscular histopathology showed mitochondrial myopathy in the three late-onset patients but not in the early-onset ones. CONCLUSIONS: Noninvasive genetic screening is recommended for mtDNA mutations in MT-NDs and MT-ATP6 genes in patients with ophthalmoplegia, muscle weakness, ataxia, and respiratory disorder. Furthermore, the lactate detection in CSF and the brain MRI scanning are suggested as the diagnosis methods for LS patients with mtDNA mutations.

Late-onset cobalamin C deficiency Chinese sibling patients with neuropsychiatric presentations.

The Cobalamin C deficiency (cblC), characterized with elevated methylmalonic acidemia and homocystinuria in plasma, is an inborn error of cobalamin metabolism. The late-onset cblC siblings patients were rarely reported. In this study, we analyzed the clinical presentations and treatment outcomes of late-onset cblC in Chinese sibling patients with neuropsychiatric presentations. The clinical data of four pairs of Chinese patients were retrospectively analyzed. Serum homocysteine, urine organic acids measurements, neuroimaging exams and gene analysis were carried out in all patents. Patients were reevaluated after treatments with cobalamin, folate, betaine, L-carnitine and compound vitamin B. The mean age at disease onset was 13.7 (range 2-19) years. The neuropsychiatric disturbances including cognitive decline (3/8), psychiatric disturbances (4/8), gait instability (2/8), lower extremity weakness and numbness (3/8) and thromboembolic events (1/8). Two patients suffered nephropathy. The mean serum homocysteine when patients were diagnosed was 109.4 (range 69.5-138) µM/L. The abnormal radioimaging included scoliosis by X-ray (5/6), cerebral atrophy (4/6) and spinal cord atrophy (3/6) by MRI scan. Three pairs of siblings showed heterozygous mutations of MMACHC gene including c.482G > A (4/6), c.354G > C (2/6), c.570insT (2/6), c.445_446del (2/6) and c.656_4658del (2/6). The other two siblings showed homozygous mutation with c.452A > G in MMACHC gene. After treatments, the psychiatric symptoms were obviously relieved in all the patients. In Chinese siblings with late-onset cblC, the main clinic manifestation and abnormal radioimaging were cognitive decline and cerebral atrophy respectively. The most common gene mutation was c.482G > A of MMACHC gene. The patients responded well to the treatments.

Upregulation of Interleukin 21 and Interleukin 21 Receptor in Patients with Dermatomyositis and Polymyositis.

BACKGROUND: The immunopathologic mechanism underlying dermatomyositis (DM) and polymyositis (PM) remains poorly understood. Many cytokines play a pathogenic role in DM and PM. Interleukin 21 (IL-21) has a pleiotropic effect on inflammation regulation. This study aimed to detect the serum IL-21 level and investigate the expression of IL-21 and IL-21 receptor (IL-21R) in muscle tissues of patients with DM and PM. METHODS: Biopsied muscle samples were obtained from 11 patients with DM, 12 with PM, and six controls; mRNA levels of IL-21 and IL-21R were analyzed by real-time quantitative reverse transcription-polymerase chain reaction; and immunohistochemical staining was used to evaluate the protein expression of IL-21 and IL-21R. Serum samples were obtained from 36 patients with DM, 19 with PM, and 20 healthy controls. The serum IL-21 level was detected by enzyme-linked immunosorbent assay. RESULTS: The expression of IL-21 was upregulated in patients with DM and PM. The IL-21 mRNA level was significantly increased in muscle tissues of patients with DM and PM (DM vs. control, P= 0.001; PM vs. control, P= 0.001), whereas IL-21R mRNA level in patients with DM/PM was not statistically different from that of healthy controls. Immunohistochemical staining showed both IL-21 and IL-21R were significantly expressed in the inflammatory cells in muscle tissues of patients with DM and PM. The serum IL-21 level was also significantly higher in patients with DM/PM than in controls (DM vs. control, 49.12 [45.28, 60.07] pg/ml vs. 42.54 [38.69, 48.85] pg/ml, P= 0.001; PM vs. control, 50.77 [44.19, 60.62] pg/ml vs. 42.54 [38.69, 48.85] pg/ml, P= 0.005). CONCLUSIONS: IL-21 expression is upregulated in patients with DM and PM in both muscle tissue and serum. In addition, IL-21R protein is highly expressed in affected muscle tissues of patients with DM and PM. IL-21 may play a pathogenic role through IL-21R in patients with DM and PM.

Cylindrical Spirals in Skeletal Muscles Originate From the Longitudinal Sarcoplasmic Reticulum.

Cylindrical spirals (CSs) are rare but distinct subsarcolemmal accumulations in skeletal muscle fibers. To date, CSs have been reported in only 16 patients with a variety of neuromuscular conditions. The origin and composition of CSs are unknown, although there are some morphologic similarities between CSs and tubular aggregates (TAs). To clarify the nature of CSs, we characterized the sarcoplasmic reticulum (SR) and other intracellular membrane system proteins in CSs of muscle biopsies from 2 adult Chinese siblings. Immunohistochemical studies revealed subsarcolemmal immunoreactivity for sarco/endoplasmic reticulum Ca2þ-ATPase 1 (SERCA 1) in the longitudinal SR, but no immunoreactivity for calsequestrin in the terminal cisternae or type 1 ryanodine receptor (RYR1) in the junctional SR. Muscles biopsied from 2 patients with TAs showed immunoreactivity not only for SERCA1 but also for other SR proteins, including calsequestrin and RYR1. CSs exhibited no immunoreactivity for the Golgi apparatus marker GM130, the nuclear membrane emerin, desmin, the autophagosome marker LC3, the lysosomal membrane marker LAMP2, dystrophin, or myosin. Our results suggest CSs may originate only from the longitudinal SR, whereas TAs are composed of both the junctional and longitudinal SR. Immunochemical staining with antibodies against calsequestrin and RYR1 help to distinguish these 2 pathological alterations.