The spontaneous differentiation and chromosome loss in iPSCs of human trisomy 18 syndrome

The importance of the trisomy 21 local cutoff value evaluation for prenatal screening in the second trimester of pregnancy

OBJECTIVE

The aim of this work was to compare different local cutoff values (LCV) and inline cutoff values (ICV) in pregnant women in the second trimester at high risk for carrying fetuses with trisomy 21.

METHODS

This retrospective cohort study analyzed prenatal screening outcomes in pregnant women (n = 311,561). The receiver operating characteristic curve was used to evaluate the diagnostic significance of the trisomy 21 risk value, alpha-fetoprotein, and free beta human chorionic gonadotropin multiple of the median for predicting trisomy 21 risk. The cutoff value corresponding to the maximal Youden index was taken as the LCV. The screening efficiency of both cutoff values was compared.

RESULTS

The LCV cutoff value was lower than the ICV cutoff value (1/643 vs 1/270). The sensitivity increased by 19.80%, the positive predictive value decreased by 0.20%, and the false-positive rate increased by 6.50%.

CONCLUSION

The LCV should be used to determine trisomy 21 risk, which can increase the detection rate of trisomy 21 in the second trimester.

Dual human iPSC-derived cardiac lineage cell-seeding extracellular matrix patches promote regeneration and long-term repair of infarcted hearts

Human pluripotent stem cell-derived cardiovascular progenitor cells (hCVPCs) and cardiomyocytes (hCMs) possess therapeutic potential for infarcted hearts; however, their efficacy needs to be enhanced. Here we tested the hypotheses that the combination of decellularized porcine small intestinal submucosal extracellular matrix (SIS-ECM) with hCVPCs, hCMs, or dual of them (Mix, 1:1) could provide better therapeutic effects than the SIS alone, and dual hCVPCs with hCMs would exert synergic effects in cardiac repair. The data showed that the SIS patch well supported the growth of hCVPCs and hCMs. Epicardially implanted SIS-hCVPC, SIS-hCM, or SIS-Mix patches at 7-day post-myocardial infarction significantly ameliorated functional worsening, ventricular dilation and scar formation at 28- and 90-day post-implantation in C57/B6 mice, whereas the SIS only mildly improved function at 90-day post-implantation. Moreover, the SIS and SIS-cell patches improved vascularization and suppressed MI-induced cardiomyocyte hypertrophy and expression of Col1 and Col3, but only the SIS-hCM and the SIS-Mix patches increased the ratio of collagen III/I fibers in the infarcted hearts. Further, the SIS-cell patches stimulated cardiomyocyte proliferation via paracrine action. Notably, the SIS-Mix had better improvements in cardiac function and structure, engraftments, and cardiomyocyte proliferation. Proteomic analysis showed distinct biological functions of exclusive proteins secreted from hCVPCs and hCMs, and more exclusive proteins secreted from co-cultivated hCVPCs and hCMs than mono-cells involving in various functional processes essential for infarct repair. These findings are the first to demonstrate the efficacy and mechanisms of mono- and dual-hCVPC- and hCM-seeding SIS-ECM for repair of infarcted hearts based on the side-by-side comparison.

Integrative epigenome profiling of 47XXY provides insights into whole genomic DNA hypermethylation and active chromatin accessibility

Klinefelter syndrome (KS, 47XXY) is a disorder characterized by sex chromosomal aneuploidy, which may lead to changes in epigenetic regulations of gene expression. To define epigenetic architectures in 47XXY, we annotated DNA methylation in euploid males (46XY) and females (46XX), and 47XXY individuals using whole genome bisulfite sequencing (WGBS) and integrated chromatin accessbilty, and detected abnormal hypermethylation in 47XXY. Furthermore, we detected altered chromatin accessibility in 47XXY, in particular in chromosome X, using Assay for Transposase-Accessible Chromatin sequencing (ATAC-seq) in cultured amniotic cells. Our results construct the whole genome-wide DNA methylation map in 47XXY, and provide new insights into the early epigenomic dysregulation resulting from an extra chromosome X in 47XXY.

Single-Cell Transcriptomics of Cultured Amniotic Fluid Cells Reveals Complex Gene Expression Alterations in Human Fetuses With Trisomy 18

Trisomy 18, commonly known as Edwards syndrome, is the second most common autosomal trisomy among live born neonates. Multiple tissues including cardiac, abdominal, and nervous systems are affected by an extra chromosome 18. To delineate the complexity of anomalies of trisomy 18, we analyzed cultured amniotic fluid cells from two euploid and three trisomy 18 samples using single-cell transcriptomics. We identified 6 cell groups, which function in development of major tissues such as kidney, vasculature and smooth muscle, and display significant alterations in gene expression as detected by single-cell RNA-sequencing. Moreover, we demonstrated significant gene expression changes in previously proposed trisomy 18 critical regions, and identified three new regions such as 18p11.32, 18q11 and 18q21.32, which are likely associated with trisomy 18 phenotypes. Our results indicate complexity of trisomy 18 at the gene expression level and reveal genetic reasoning of diverse phenotypes in trisomy 18 patients.

Two-step induction of trabecular meshwork cells from induced pluripotent stem cells for glaucoma

Glaucoma is a leading cause of irreversible blindness worldwide. Reducing intraocular pressure is currently the only effective treatment. Elevated intraocular pressure is associated with increased resistance of the outflow pathway, mainly the trabecular meshwork (TM). Despite great progress in the field, the development of novel and effective treatment for glaucoma is still challenging. In this study, we reported that human induced pluripotent stem cells (iPSCs) can be cultured as colonies and monolayer cells expressing OCT4, alkaline phosphatase, SSEA4 and SSEA1. After induction to neural crest cells (NCCs) positive to NGFR and HNK1, the iPSCs can differentiate into TM cells. The induced iPSC-TM cells expressed TM cell marker CHI3L1, were responsive to dexamethasone treatment with increased expression of myocilin, ANGPTL7, and formed CLANs, comparable to primary TM cells. To the best of our knowledge, this is the first study that induces iPSCs to TM cells through a middle neural crest stage, which ensures a stable NCC pool and ensures the high output of the same TM cells. This system can be used to develop personalized treatments using patient-derived iPSCs, explore high throughput screening of new drugs focusing on TM response for controlling intraocular pressure, and investigate stem cell-based therapy for TM regeneration.

Chromosome Transplantation: A Possible Approach to Treat Human X-linked Disorders

Many human genetic diseases are associated with gross mutations such as aneuploidies, deletions, duplications, or inversions. For these “structural” disorders, conventional gene therapy, based on viral vectors and/or on programmable nuclease-mediated homologous recombination, is still unsatisfactory. To correct such disorders, chromosome transplantation (CT), defined as the perfect substitution of an endogenous defective chromosome with an exogenous normal one, could be applied. CT re-establishes a normal diploid cell, leaving no marker of the procedure, as we have recently shown in mouse pluripotent stem cells. To prove the feasibility of the CT approach in human cells, we used human induced pluripotent stem cells (hiPSCs) reprogrammed from Lesch-Nyhan (LN) disease patients, taking advantage of their mutation in the X-linked HPRT gene, making the LN cells selectable and distinguishable from the resistant corrected normal cells. In this study, we demonstrate, for the first time, that CT is feasible in hiPSCs: the normal exogenous X chromosome was first transferred using an improved chromosome transfer system, and the extra sex chromosome was spontaneously lost. These CT cells were functionally corrected and maintained their pluripotency and differentiation capability. By inactivation of the autologous HPRT gene, CT paves the way to the correction of hiPSCs from several X-linked disorders.

The Genomic Health of Human Pluripotent Stem Cells: Genomic Instability and the Consequences on Nuclear Organization

Human pluripotent stem cells (hPSCs) are increasingly used for cell-based regenerative therapies worldwide, with embryonic and induced pluripotent stem cells as potential treatments for debilitating and chronic conditions, such as age-related macular degeneration, Parkinson's disease, spinal cord injuries, and type 1 diabetes. However, with the level of genomic anomalies stem cells generate in culture, their safety may be in question. Specifically, hPSCs frequently acquire chromosomal abnormalities, often with gains or losses of whole chromosomes. This review discusses how important it is to efficiently and sensitively detect hPSC aneuploidies, to understand how these aneuploidies arise, consider the consequences for the cell, and indeed the individual to whom aneuploid cells may be administered.

Establishment of a human trisomy 18 induced pluripotent stem cell line from amniotic fluid cells

Trisomy 18 (18T) is the second most common autosomal trisomy syndrome in humans, but the detailed mechanism of its pathology remains unclear due to the lack of appropriate models of this disease. To resolve this problem, the current study reprogrammed human 18T amniotic fluid cells (AFCs) into an induced pluripotent stem cell (iPSC) line by introducing integration-free episomal vectors carrying pCXLE-hOCT3/4-shp53-F, pCXLE-hSK, pCXLE-hUL, and pCXWB-EBNA1. The pluripotency of 18T-iPSCs was subsequently validated by alkaline phosphatase staining, detection of iPSC biomarkers using real-time PCR and flow cytometry, detection of embryoid body (EB) formation, and detection of in vivo teratoma formation. Moreover, this study also investigated the transcriptomic profiles of 18T-iPSCs using RNA sequencing, and several gene clusters associated with the clinical manifestations of 18T were identified. In summary, the generated induced pluripotent stem cells line has typical pluripotency characteristics and can provide a useful tool with which to understand the development of 18T.