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 appro-aches 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 trans-plantation 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.

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 mitochondrial disease in a patient with MELAS and mitochondrial DNA T14487C mutation

To the Editor: Mitochondrial encephalomyopathy with lactate acidosis and stroke-like episodes (MELAS) is one of the most common multisystem mitochondrial disorders with broad clinical manifestations.[1] It is usually caused by point mutations in the mitochondrial MT-TL1 gene, which accounts for approximately 80% of mutations in individuals with MELAS syndrome.[2] Pathogenic mitochondrial DNA (mtDNA) mutations were first described in 1980[3] and m.l4487T>C is a known pathogenic mtDNA mutation,[4] which has been reported in patients with Leigh syndrome, optic neuropathy, ptosis, dystonia, and encephalomyopathy. We herein report a patient with late-onset MELAS syndrome with the m.l4487T>C mutation for the first time.

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.lnterleukin 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-21 R） 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-21 R 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 I L-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 =0.00l;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.

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 upregulated in muscles from all three subgroups of IMMs(NC vs.LSD,U=0.000,P=0.006;NC vs.PD,[7=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(17=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.

Myotonic Dystrophy Type I with Syringomyelia in a Young Patient

Myotonic dystrophy type 1 （DM1） is the most common disease causing muscle weakness and atrophy in adults. The prevalence of DM1 in China is not clear. DM1 is an autosomal dominant genetic disorder associated with the cytosine-thynline-guanine （CTG） repeat expansion in 3＇untranslated region in dystrophia myotonica-protein kinase （DMPK） gene on chromosome 19q 13.3. In DM 1, CTG pathological repeat numbers are more than 50. The size of CTG repeat expansion is associated with the time of clinical phenotypes onset and severity The coexistence of DMI and syrlngomyelia is rare. Here, we report DM1 coexisting with syringonlyelia in a Chinese male patient.