Chromosome microduplication in somatic cells decreases the genetic stability of human reprogrammed somatic cells and results in pluripotent stem cells

Molecular signature and colony morphology affect in vitro pluripotency of porcine induced pluripotent stem cells

Overall efficiency of cell reprogramming for porcine fibroblasts into induced pluripotent stem cells (iPSCs) is currently poor, and few cell lines have been established. This study examined gene expression during early phase of cellular reprogramming in the relationship to the iPSC colony morphology and in vitro pluripotent characteristics. Fibroblasts were reprogrammed with OCT4, SOX2, KLF4 and c-MYC. Two different colony morphologies referred to either compact (n = 10) or loose (n = 10) colonies were further examined for proliferative activity, gene expression and in vitro pluripotency. A total of 1,697 iPSC-like colonies (2.34%) were observed after gene transduction. The compact colonies contained with tightly packed cells with a distinct-clear border between the colony and feeder cells, while loose colonies demonstrated irregular colony boundary. For quantitative expression of genes responsible for early phase cell reprogramming, the Dppa2 and EpCAM were significantly upregulated while NR0B1 was downregulated in compact colonies compared with loose phenotype (p < .05). Higher proportion of compact iPSC phenotype (5 of 10, 50%) could be maintained in undifferentiated state for more than 50 passages compared unfavourably with loose morphology (3 of 10, 30%). All iPS cell lines obtained from these two types of colony morphologies expressed pluripotent genes and proteins (OCT4, NANOG and E-cadherin). In addition, they could aggregate and form three-dimensional structure of embryoid bodies. However, only compact iPSC colonies differentiated into three germ layers. Molecular signature of early phase of cell reprogramming coupled with primary colony morphology reflected the in vitro pluripotency of porcine iPSCs. These findings can be simply applied for pre-screening selection of the porcine iPSC cell line.

Strategies for Cancer Immunotherapy Using Induced Pluripotency Stem Cells-Based Vaccines

Despite improvements in cancer therapy, metastatic solid tumors remain largely incurable. Immunotherapy has emerged as a pioneering and promising approach for cancer therapy and management, and in particular intended for advanced tumors unresponsive to current therapeutics. In cancer immunotherapy, components of the immune system are exploited to eliminate cancer cells and treat patients. The recent clinical successes of immune checkpoint blockade and chimeric antigen receptor T cell therapies represent a turning point in cancer treatment. Despite their potential success, current approaches depend on efficient tumor antigen presentation which are often inaccessible, and most tumors turn refractory to current immunotherapy. Patient-derived induced pluripotent stem cells (iPSCs) have been shown to share several characteristics with cancer (stem) cells (CSCs), eliciting a specific anti-tumoral response when injected in rodent cancer models. Indeed, artificial cellular reprogramming has been widely compared to the biogenesis of CSCs. Here, we will discuss the state-of-the-art on the potential implication of cellular reprogramming and iPSCs for the design of patient-specific immunotherapeutic strategies, debating the similarities between iPSCs and cancer cells and introducing potential strategies that could enhance the efficiency and therapeutic potential of iPSCs-based cancer vaccines.

Clinical experience with multiplex ligation-dependent probe amplification for microdeletion syndromes in prenatal diagnosis: 7522 pregnant Korean women

Background

Conventional cytogenetic analysis using G-band karyotyping has been the method of choice for prenatal diagnosis, accurately detecting chromosomal abnormalities larger than 5 Mb. However, the method is inefficient for detecting the submicroscopic deletions and duplications that are associated with malformations and mental retardation. This study evaluated the results of the multiplex ligation-dependent probe amplification (MLPA) P245 assay used for prenatal diagnosis in cases with unusual ultrasonographic findings or specifically where parents wanted to be tested. The objective was to compare the results from MLPA with those from conventional cytogenetic testing in order to determine their concordance and the additional diagnostic yield of MLPA over G-band karyotyping.

Results

Of the 7522 prenatal cases analyzed, 124 were found to have genomic imbalances (1.6%). Of those 124 cases, 41 had gene loss (33.6%), and 83 had gene gain (66.4%). Most of the cases with genomic imbalances (64.5%) showed no abnormal karyotype. In particular, all cases with a 4p16.3 deletion (Wolf-Hirschhorn syndrome) showed an abnormal karyotype, whereas all of those with a 22q11–13 deletion showed a normal karyotype. In most of the cases with pathogenic deletions, the indication for invasive prenatal testing was an increase in the nuchal translucency (NT) alone (51.2%). Other indications observed in the remaining cases were abnormal serum screening markers (14.6%), other ultrasonographic findings (9.8%), pregnancy through in vitro fertilization and fertility assistance (9.8%), and advanced maternal age(2.4%).

Conclusions

These results show that for fetuses with an enlarged NT or abnormal ultrasonographic findings and normal conventional karyotype, additional genetic investigation like molecular testing would be for identifying the microscopic genomic aberrations (microdeletions, microduplications) responsible for syndromic associations including structural anomalies and mental retardation.

Single-Cell Transcriptomics of Human Oocytes: Environment-Driven Metabolic Competition and Compensatory Mechanisms During Oocyte Maturation

AIMS

The mechanisms coordinating maturation with an environment-driven metabolic shift, a critical step in determining the developmental potential of human in vitro maturation (IVM) oocytes, remain to be elucidated. Here we explored the key genes regulating human oocyte maturation using single-cell RNA sequencing and illuminated the compensatory mechanism from a metabolic perspective by analyzing gene expression.

RESULTS

Three key genes that encode CoA-related enzymes were screened from the RNA sequencing data. Two of them, ACAT1 and HADHA, were closely related to the regulation of substrate production in the Krebs cycle. Dysfunction of the Krebs cycle was induced by decreases in the activity of specific enzymes. Furthermore, the activator of these enzymes, the calcium concentration, was also decreased because of the failure of influx of exogenous calcium. Although release of endogenous calcium from the endoplasmic reticulum and mitochondria met the requirement for maturation, excessive release resulted in aneuploidy and developmental incompetence. High nicotinamide nucleotide transhydrogenase expression induced NADPH dehydrogenation to compensate for the NADH shortage resulting from the dysfunction of the Krebs cycle. Importantly, high NADP⁺ levels activated DPYD to enhance the repair of DNA double-strand breaks to maintain euploidy.

INNOVATION

The present study shows for the first time that exposure to the in vitro environment can lead to the decline of energy metabolism in human oocytes during maturation but that a compensatory action maintains their developmental competence.

CONCLUSION

In vitro maturation of human oocytes is mediated through a cascade of competing and compensatory actions driven by genes encoding enzymes.

Concise Review: Molecular Cytogenetics and Quality Control: Clinical Guardians for Pluripotent Stem Cells

Now that induced pluripotent stem cell (iPSC)‐based transplants have been performed in humans and organizations have begun producing clinical‐grade iPSCs, it is imperative that strict quality control standards are agreed upon. This is essential as both ESCs and iPSCs have been shown to accumulate genomic aberrations during long‐term culturing. These aberrations can include copy number variations, trisomy, amplifications of chromosomal regions, deletions of chromosomal regions, loss of heterozygosity, and epigenetic abnormalities. Moreover, although the differences between iPSCs and ESCs appear largely negligible when a high enough n number is used for comparison, the reprogramming process can generate further aberrations in iPSCs, including copy number variations and deletions in tumor‐suppressor genes. If mutations or epigenetic signatures are present in parental cells, these can also be carried over into iPSCs. To maximize patient safety, we recommend a set of standards to be utilized when preparing iPSCs for clinical use. Reprogramming methods that do not involve genomic integration should be used. Cultured cells should be grown using feeder‐free and serum‐free systems to avoid animal contamination. Karyotyping, whole‐genome sequencing, gene expression analyses, and standard sterility tests should all become routine quality control tests. Analysis of mitochondrial DNA integrity, whole‐epigenome analyses, as well as single‐cell genome sequencing of large cell populations may also prove beneficial. Furthermore, clinical‐grade stem cells need to be produced under accepted regulatory good manufacturing process standards. The creation of haplobanks that provide major histocompatibility complex matching is also recommended to improve allogeneic stem cell engraftment. Stem Cells Translational Medicine2018;7:867–875

Induced Pluripotent Stem Cells and Outer Retinal Disease

The retina, which is composed of multiple layers of differing cell types, has been considered the first choice for gene therapy, disease modeling, and stem cell-derived retinal cell transplant therapy. Because of its special characteristics, the retina, located in the posterior part of the eye, can be well observed directly after gene therapy or transplantation. The blood-retinal barrier is part of a specialized ocular microenvironment that is immune privileged. This protects transplanted cells and tissue. Having two eyes makes perfect natural control possible after a single eye receives gene or stem cell therapy. For this reason, research about exploring retinal diseases' underlying molecular mechanisms and potential therapeutic approach using stem cell technique has been developing rapidly. This review is to present an up-to-date summary of the iPSC's sources, variations, differentiation methods, and the wide-ranging application of iPSCs-RPCS or iPSCs-RPE on retinal disease modeling, diagnostics, and therapeutics.

Concise Review: Pluripotent Stem Cell-Derived Cardiac Cells, A Promising Cell Source for Therapy of Heart Failure: Where Do We Stand?

Heart failure is still a major cause of hospitalization and mortality in developed countries. Many clinical trials have tested the use of multipotent stem cells as a cardiac regenerative medicine. The benefit for the patients of this therapeutic intervention has remained limited. Herein, we review the pluripotent stem cells as a cell source for cardiac regeneration. We more specifically address the various challenges of this cell therapy approach. We question the cell delivery systems, the immune tolerance of allogenic cells, the potential proarrhythmic effects, various drug mediated interventions to facilitate cell grafting and, finally, we describe the pathological conditions that may benefit from such an innovative approach. As members of a transatlantic consortium of excellence of basic science researchers and clinicians, we propose some guidelines to be applied to cell types and modes of delivery in order to translate pluripotent stem cell cardiac derivatives into safe and effective clinical trials.