Isolation of cardiac cells from E8.5 yolk sac by ALCAM (CD166) expression

Human Wharton's Jelly-Derived Mesenchymal Stem Cells Minimally Improve the Growth Kinetics and Cardiomyocyte Differentiation of Aged Murine Cardiac c-kit Cells in In Vitro without Rejuvenating Effect

Cardiac c-kit cells show promise in regenerating an injured heart. While heart disease commonly affects elderly patients, it is unclear if autologous cardiac c-kit cells are functionally competent and applicable to these patients. This study characterised cardiac c-kit cells (CCs) from aged mice and studied the effects of human Wharton’s Jelly-derived mesenchymal stem cells (MSCs) on the growth kinetics and cardiac differentiation of aged CCs in vitro. CCs were isolated from 4-week- and 18-month-old C57/BL6N mice and were directly co-cultured with MSCs or separated by transwell insert. Clonogenically expanded aged CCs showed comparable telomere length to young CCs. However, these cells showed lower Gata4, Nkx2.5, and Sox2 gene expressions, with changes of 2.4, 3767.0, and 4.9 folds, respectively. Direct co-culture of both cells increased aged CC migration, which repopulated 54.6 ± 4.4% of the gap area as compared to aged CCs with MSCs in transwell (42.9 ± 2.6%) and CCs without MSCs (44.7 ± 2.5%). Both direct and transwell co-culture improved proliferation in aged CCs by 15.0% and 16.4%, respectively, as traced using carboxyfluorescein succinimidyl ester (CFSE) for three days. These data suggest that MSCs can improve the growth kinetics of aged CCs. CCs retaining intact telomere are present in old hearts and could be obtained based on their self-renewing capability. Although these aged CCs with reduced growth kinetics are improved by MSCs via cell–cell contact, the effect is minimal.

Induction of cardiomyocyte‑like cells from hair follicle cells in mice

Hair follicles (HFs) are a well‑characterized niche for adult stem cells (SCs), and include epithelial and melanocytic SCs. HF cells are an accessible source of multipotent adult SCs for the generation of the interfollicular epidermis, HF structures and sebaceous glands in addition to the reconstitution of novel HFs in vivo. In the present study, it was demonstrated that HF cells are able to be induced to differentiate into cardiomyocyte‑like cells in vitro under specific conditions. It was determined that HF cells cultured on OP9 feeder cells in KnockOut‑Dulbecco's modified Eagle's medium/B27 in the presence of vascular endothelial growth factors differentiated into cardiomyocyte‑like cells that express markers specific to cardiac lineage, but do not express non‑cardiac lineage markers including neural stem/progenitor cell, HF bulge cells or undifferentiated spermatogonia markers. These cardiomyocyte‑like cells exhibited a spindle‑ and filament‑shaped morphology similar to that presented by cardiac muscles and exhibited spontaneous beating that persisted for over 3 months. These results demonstrate that SC reprogramming and differentiation may be induced without resulting in any genetic modification, which is important for the clinical applications of SCs including tissue and organ regeneration.

Induced Pluripotent Stem Cell-Derived Mesenchymal Stromal Cells Are Functionally and Genetically Different From Bone Marrow-Derived Mesenchymal Stromal Cells

There has been considerable interest in the generation of functional mesenchymal stromal cell (MSC) preparations from induced pluripotent stem cells (iPSCs) and this is now regarded as a potential source of unlimited, standardized, high‐quality cells for therapeutic applications in regenerative medicine. Although iMSCs meet minimal criteria for defining MSCs in terms of marker expression, there are substantial differences in terms of trilineage potential, specifically a marked reduction in chondrogenic and adipogenic propensity in iMSCs compared with bone marrow‐derived (BM) MSCs. To reveal the cellular basis underlying these differences, we conducted phenotypic, functional, and genetic comparisons between iMSCs and BM‐MSCs. We found that iMSCs express very high levels of both KDR and MSX2 compared with BM‐MSCs. In addition, BM‐MSCs had significantly higher levels of PDGFRα. These distinct gene expression profiles were maintained during culture expansion, suggesting that prepared iMSCs are more closely related to vascular progenitor cells (VPCs). Although VPCs can differentiate along the chondrogenic, osteogenic, and adipogenic pathways, they require different inductive conditions compared with BM‐MSCs. These observations suggest to us that iMSCs, based on current widely used preparation protocols, do not represent a true alternative to primary MSCs isolated from BM. Furthermore, this study highlights the fact that high levels of expression of typical MSC markers such as CD73, CD90, and CD105 are insufficient to distinguish MSCs from other mesodermal progenitors in differentiated induced pluripotent stem cell cultures. stem cells2019;37:754–765

A Bmp Reporter Transgene Mouse Embryonic Stem Cell Model as a Tool to Identify and Characterize Chemical Teratogens

Embryonic stem cells (ESCs) were first isolated from mouse embryos more than 30 years ago. They have proven invaluable not only in generating genetically modified mice that allow for analysis of gene function in tissue development and homeostasis but also as models for genetic disease. In addition, ESCs in vitro are finding inroads in pharmaceutical and toxicological testing, including the identification of teratogenic compounds. Here, we describe the use of a bone morphogenetic protein (Bmp)-reporter ESC line, isolated from a well-characterized transgenic mouse line, as a new tool for the identification of chemical teratogens. The Bmp-mediated expression of the green fluorescent protein enabled the quantification of dose- and time-dependent effects of valproic acid as well as retinoic acid. Significant effects were detectable at concentrations that were comparable to the ones observed in the classical embryonic stem cell test, despite the fact that the reporter gene is expressed in distinct cell types, including endothelial and endodermal cells. Thus these cells provide a valuable new tool for the identification and characterization of relevant mechanisms of embryonic toxicity.

Deconvoluting the ontogeny of hematopoietic stem cells

Two different models describe the development of definitive hematopoiesis and hematopoietic stem cells (HSCs). In one of these, the visceral yolk sac serves as a starting point of relatively lengthy developmental process culminating in the fetal liver hematopoiesis. In another, the origin of adult hematopoiesis is split between the yolk sac and the dorsal aorta, which has a peculiar capacity to generate definitive HSCs. Despite a large amount of experimental data consistent with the latter view, it becomes increasingly unsustainable in the light of recent cell tracing studies. Moreover, analysis of the published studies supporting the aorta-centered version uncovers significant caveats in standard experimental approach and argumentation. As a result, the theory cannot offer feasible cellular mechanisms of the HSC emergence. This review summarizes key efforts to discern the developmental pathway of the adult-type HSCs and attempts to put forward a hypothesis on the inflammatory mechanisms of hematopoietic ontogenesis.

CD166 and regulation of hematopoiesis

PURPOSE OF REVIEW

Many surface antigens have been previously used to identify hematopoietic stem cells or cellular elements of the hematopoietic niche. However, to date, not a single surface marker has been identified as a common marker expressed on murine and human hematopoietic stem cells and on cells of the hematopoietic niche. Recently, a few laboratories, including ours, recognized the importance of CD166 as a functional marker on both stem cells and osteoblasts and have begun to characterize the role of CD166 in hematopoiesis.

RECENT FINDINGS

Expression of CD166 on hematopoietic cells and cells in the marrow microenvironment was first reported more than a decade ago. Lately, however, a more prominent role for CD166 in normal hematopoiesis and in cancer biology including metastasis began to emerge. This review will cover the significance of CD166 in identifying normal hematopoietic stem cells and cells of the hematopoietic niche and highlight how CD166-mediated homophilic interactions between both cell types may be critical for stem cell function.

SUMMARY

The conserved homology between murine and human CD166 and its involvement in metastasis provides an excellent bridge for translational investigations aimed at enhancing stem cell engraftment and clinical utility of stem cells and at using CD166 as a therapeutic target in cancer.

Embryonic stem cell-derived CD166+ precursors develop into fully functional sinoatrial-like cells

RATIONALE

A cell-based biological pacemaker is based on the differentiation of stem cells and the selection of a population displaying the molecular and functional properties of native sinoatrial node (SAN) cardiomyocytes. So far, such selection has been hampered by the lack of proper markers. CD166 is specifically but transiently expressed in the mouse heart tube and sinus venosus, the prospective SAN.

OBJECTIVE

We have explored the possibility of using CD166 expression for isolating SAN progenitors from differentiating embryonic stem cells.

METHODS AND RESULTS

We found that in embryonic day 10.5 mouse hearts, CD166 and HCN4, markers of the pacemaker tissue, are coexpressed. Sorting embryonic stem cells for CD166 expression at differentiation day 8 selects a population of pacemaker precursors. CD166+ cells express high levels of genes involved in SAN development (Tbx18, Tbx3, Isl-1, Shox2) and function (Cx30.2, HCN4, HCN1, CaV1.3) and low levels of ventricular genes (Cx43, Kv4.2, HCN2, Nkx2.5). In culture, CD166+ cells form an autorhythmic syncytium composed of cells morphologically similar to and with the electrophysiological properties of murine SAN myocytes. Isoproterenol increases (+57%) and acetylcholine decreases (-23%) the beating rate of CD166-selected cells, which express the β-adrenergic and muscarinic receptors. In cocultures, CD166-selected cells are able to pace neonatal ventricular myocytes at a rate faster than their own. Furthermore, CD166+ cells have lost pluripotency genes and do not form teratomas in vivo.

CONCLUSIONS

We demonstrated for the first time the isolation of a nonteratogenic population of cardiac precursors able to mature and form a fully functional SAN-like tissue.

Intrauterine calorie restriction affects placental DNA methylation and gene expression

Maternal nutrient restriction causes the development of adult onset chronic diseases in the intrauterine growth restricted (IUGR) fetus. Investigations in mice have shown that either protein or calorie restriction during pregnancy leads to glucose intolerance, increased fat mass, and hypercholesterolemia in adult male offspring. Some of these phenotypes are shown to persist in successive generations. The molecular mechanisms underlying IUGR remain unclear. The placenta is a critical organ for mediating changes in the environment and the development of embryos. To shed light on molecular mechanisms that might affect placental responses to differing environments we examined placentas from mice that had been exposed to different diets. We measured gene expression and whole genome DNA methylation in both male and female placentas of mice exposed to either caloric restriction or ad libitum diets. We observed several differentially expressed pathways associated with IUGR phenotypes and, most importantly, a significant decrease in the overall methylation between these groups as well as sex-specific effects that are more pronounced in males. In addition, a set of significantly differentially methylated genes that are enriched for known imprinted genes were identified, suggesting that imprinted loci may be particularly susceptible to diet effects. Lastly, we identified several differentially methylated microRNAs that target genes associated with immunological, metabolic, gastrointestinal, cardiovascular, and neurological chronic diseases, as well as genes responsible for transplacental nutrient transfer and fetal development.

High-purity enrichment of functional cardiovascular cells from human iPS cells

AIMS

A variety of human inherited heart diseases affect the normal functions of cardiomyocytes (CMs), endothelial cells (ECs), or smooth muscle cells (SMCs). To study human heart disease and generate cardiac cells for basic and translational research, an efficient strategy is needed for production of cardiac lineages from human stem cells. In the present study, a highly reproducible method was developed that can simultaneously enrich a large number of CMs and cardiac SMCs and ECs from human induced pluripotent stem (iPS) cells with high purity.

METHODS AND RESULTS

Human multipotent cardiovascular progenitor cells were generated from human iPS cells, followed by selective differentiation of the multipotent cardiovascular progenitor cells into CMs, ECs, and SMCs. With further fluorescence-activated cell sorting, each of the three cardiovascular cell types could be enriched with high purity (>90%). These enriched cardiovascular cells exhibited specific gene expression signatures and normal functions when assayed both in vitro and in vivo. Moreover, CMs purified from iPS cells derived from a patient with LEOPARD syndrome, a disease characterized by cardiac hypertrophy, showed the expected up-regulated expression of genes associated with cardiac hypertrophy.

CONCLUSIONS

Overall, our technical advance provides the means for generating a renewable resource of pure human cardiovascular cells that can be used to dissect the mechanisms of human inherited heart disease and for the future development of drug and cell therapeutics for heart disease.

Glycine decarboxylase activity drives non-small cell lung cancer tumor-initiating cells and tumorigenesis

Identification of the factors critical to the tumor-initiating cell (TIC) state may open new avenues in cancer therapy. Here we show that the metabolic enzyme glycine decarboxylase (GLDC) is critical for TICs in non-small cell lung cancer (NSCLC). TICs from primary NSCLC tumors express high levels of the oncogenic stem cell factor LIN28B and GLDC, which are both required for TIC growth and tumorigenesis. Overexpression of GLDC and other glycine/serine enzymes, but not catalytically inactive GLDC, promotes cellular transformation and tumorigenesis. We found that GLDC induces dramatic changes in glycolysis and glycine/serine metabolism, leading to changes in pyrimidine metabolism to regulate cancer cell proliferation. In the clinic, aberrant activation of GLDC correlates with poorer survival in lung cancer patients, and aberrant GLDC expression is observed in multiple cancer types. This link between glycine metabolism and tumorigenesis may provide novel targets for advancing anticancer therapy.

Efficient and scalable purification of cardiomyocytes from human embryonic and induced pluripotent stem cells by VCAM1 surface expression

Rationale

Human embryonic and induced pluripotent stem cells (hESCs/hiPSCs) are promising cell sources for cardiac regenerative medicine. To realize hESC/hiPSC-based cardiac cell therapy, efficient induction, purification, and transplantation methods for cardiomyocytes are required. Though marker gene transduction or fluorescent-based purification methods have been reported, fast, efficient and scalable purification methods with no genetic modification are essential for clinical purpose but have not yet been established. In this study, we attempted to identify cell surface markers for cardiomyocytes derived from hESC/hiPSCs.

Method and Result

We adopted a previously reported differentiation protocol for hESCs based on high density monolayer culture to hiPSCs with some modification. Cardiac troponin-T (TNNT2)-positive cardiomyocytes appeared robustly with 30–70% efficiency. Using this differentiation method, we screened 242 antibodies for human cell surface molecules to isolate cardiomyocytes derived from hiPSCs and identified anti-VCAM1 (Vascular cell adhesion molecule 1) antibody specifically marked cardiomyocytes. TNNT2-positive cells were detected at day 7–8 after induction and 80% of them became VCAM1-positive by day 11. Approximately 95–98% of VCAM1-positive cells at day 11 were positive for TNNT2. VCAM1 was exclusive with CD144 (endothelium), CD140b (pericytes) and TRA-1-60 (undifferentiated hESCs/hiPSCs). 95% of MACS-purified cells were positive for TNNT2. MACS purification yielded 5−10×10⁵ VCAM1-positive cells from a single well of a six-well culture plate. Purified VCAM1-positive cells displayed molecular and functional features of cardiomyocytes. VCAM1 also specifically marked cardiomyocytes derived from other hESC or hiPSC lines.

Conclusion

We succeeded in efficiently inducing cardiomyocytes from hESCs/hiPSCs and identifying VCAM1 as a potent cell surface marker for robust, efficient and scalable purification of cardiomyocytes from hESC/hiPSCs. These findings would offer a valuable technological basis for hESC/hiPSC-based cell therapy.