An embryonic origin for medulloblastoma

Medulloblastoma is a common brain tumor of children. Three differentiated cell types are found in medulloblastomas: neurons, glia, and muscle cells. Because of the presence of multiple differentiated cell types these tumors were named after a postulated cerebellar stem cell, the medulloblast, that would give rise to the differentiated cells found in the tumors. We describe a cell line with the properties expected of the postulated medulloblast. The rat cerebellar cell line ST15A expresses an intermediate filament, nestin, that is characteristic of neuroepithelial stem cells. ST15A cells can differentiate, gaining either neuronal or glial properties. In this paper we show that the same clonal cell can also differentiate into muscle cells. This result suggests that a single neuroectodermal cell can give rise to the different cell types found in medulloblastoma. We also show expression of nestin in human medulloblastoma tissue and in a medulloblastoma-derived cell line. Both the properties of the ST15A cell line and the expression of nestin in medulloblastoma support a neuroectodermal stem cell origin for this childhood tumor.     

Murine embryonic stem cells as a model for human embryonic stem-cell research

Over the last several decades, murine embryonic stem cells (mESCs) have been used as a model for human embryonic stem cell (hESC) research. The relevance of this approach has not yet been proven. There is a great deal of evidence that is indicative of substantial differences between these two cell types. An analysis of the literature shows that the differences concern ESC proliferation, self-renewal, and differentiation. Consequently, mESC may be considered as a model object for hESC studies only for some aspects of their biology. The alternative model objects, such as primate ESC, are also discussed briefly in this review.     

Requirements for human embryonic stem cells

‘Requirements for Human Embryonic Stem Cells’ is the first set of guidelines on human embryonic stem cells in China, jointly drafted and agreed upon by experts from the Chinese Society for Stem Cell Research. This standard specifies the technical requirements, test methods, test regulations, instructions for use, labelling requirements, packaging requirements, storage requirements and transportation requirements for human embryonic stem cells, which is applicable to the quality control for human embryonic stem cells. It was originally released by the China Society for Cell Biology on 26 February 2019 and was further revised on 30 April 2020. We hope that publication of these guidelines will promote institutional establishment, acceptance and execution of proper protocols, and accelerate the international standardization of human embryonic stem cells for applications.     

Anin vitro model for chick embryonic notochords

A two step method to obtain mesenchymal free 3.5 day old chick embryonic notochordsin vitro is presented. 1.) Notochords are isolated by mechanical microdissection from the embryos below the head and above the leg-buds. 2.) The dissected notochords are trypsinized to eliminate contaminating mesenchymal cells, while the perinotochordal sheath (PNS) is retained. After isolation and trypsinization, notochords are cut in standard 8mm lengths, explantedin vitro and incubated at 37°C. Immediately before incubation and after 3 and 6 daysin vitro, notochords are fixed and stained to follow the morphological changes. The total DNA content of notochords is measured before and during maintenancein vitro to evaluate their metabolic activities. Results show that during thein vitro period, the isolated mesenchymal free notochordal fragments can conserve their characteristic architecture. The total DNA content measurements indicate proliferative activity and a high viability of the notochords in ourin vitro system. In the present study, an isolation andin vitro method is offered which might be an effective tool to study the metabolic activities of chick embryonic notochordsin vitro in comparison toin vivo behaviour, in order to study the underlying mechanism of notochord regression.     

Morphology of the embryonic and hatchling american alligator ductus arteriosi and implications for embryonic cardiovascular shunting

The ductus arteriosi (DA) are embryonic blood vessels found in amniotic vertebrates that shunt blood away from the pulmonary artery and lungs and toward the aorta. Here, we examine changes in morphology of the right and left DA (LDA), and right and left aorta (LAo) from embryonic and hatchling alligators. The developing alligator has two‐patent DA that join the right and LAo. Both DA exhibit a muscular phenotype composed of an internal smooth muscle layer (2–4 cells thick). At hatching, the lumen diameter of both DA decreases as the vessels begin to close within the first 12 h of posthatch life. Between day 1 and day 12 posthatching, the vessel becomes fully occluded with endothelial and smooth muscle cells filling the lumen. A number of DA from hatchlings contained blood clots along their length. The lumen of the full term alligator DA is reduced in comparison with the full term chicken DA. The developing alligator embryo has an additional right‐to‐left shunt pathway in the LAo arising from the right ventricle. The embryonic LAo diameter is twice the diameter of either the right DA or LDA, providing a lower resistance pathway for blood leaving the right ventricle. On the basis of these findings, we propose that the paired DA of the embryonic alligator have a reduced role in the embryonic right‐to‐left shunt of blood from the right ventricle when compared with the avian DA. J. Morphol. 2011. © 2011 Wiley Periodicals, Inc.     

Xenopus Dab2 is required for embryonic angiogenesis

Background  

The molecular mechanisms governing the formation of the embryonic vascular system remain poorly understood. Here, we show that Disabled-2 (Dab2), a cytosolic adaptor protein, has a pivotal role in the blood vessel formation in Xenopus early embryogenesis.     

FGF-16 is required for embryonic heart development

Fibroblast growth factor 16 (FGF-16) expression has previously been detected in mouse heart at mid-gestation in the endocardium and epicardium, suggesting a role in embryonic heart development. More specifically, exogenously applied FGF-16 has been shown to stimulate growth of embryonic myocardial cells in tissue explants. We have generated mice lacking FGF-16 by targeting the Fgf16 locus on the X chromosome. Elimination of Fgf16 expression resulted in embryonic death as early as day 11.5 (E11.5). External abnormalities, including hemorrhage in the heart and ventral body region as well as facial defects, began to appear in null embryos from E11.5. Morphological analysis of FGF-16 null hearts revealed cardiac defects including chamber dilation, thinning of the atrial and ventricular walls, and poor trabeculation, which were visible at E10.5 and more pronounced at E11.5. These findings indicate FGF-16 is required for embryonic heart development in mid-gestation through its positive effect on myocardial growth.     

Protocols for cardiac differentiation of embryonic stem cells

Both mouse and human embryonic stem (ES) cells provide a powerful model of early cardiogenesis. Furthermore engineering of cardiac progenitors or cardiomyocytes from ES cells offers a tool for drug screening in toxicology or to search for molecules to improve and scale up the process of cardiac differentiation using high throughput screening technology. Spontaneous differentiation of ES cells into cardiomyocytes is however limited. Herein, I described simple protocols to commit both mouse and human ES cells toward a cardiac lineage and in turn to improve the process of in vitro differentiation.     

The chicken as a model for embryonic development

The traditional strength of chicken embryos for studying development is that they are readily manipulated. This has led to some major discoveries in developmental biology such as the demonstration that the neural crest gives rise to almost the entire peripheral nervous system and the identification of signalling centres that specify the pattern of structures in the central nervous system and limb. More recently with the burgeoning discovery of developmentally important genes, chicken embryos have provided useful models for testing function. Uncovering the molecular basis of development provides direct links with clinical genetics. In addition, since many genes that have crucial roles in development are also expressed in tumours, basic research on chickens has implications for understanding human health and disease. Now that the chicken genome has been sequenced and genomic resources for chicken are becoming increasingly available, this opens up opportunities for combining these new technologies with the manipulability of chicken embryos and also exploiting comparative genomics.     

Human embryonic stem cell and embryonic germ cell lines

Undifferentiated human embryonic stem (ES) cells and embryonic germ (EG) cells can be cultured indefinitely and yet maintain the potential to form many or all of the differentiated cells in the body. Human ES and EG cells provide an exciting new model for understanding the differentiation and function of human tissue, offer new strategies for drug discovery and testing, and promise new therapies based on the transplantation of ES and EG cell-derived tissues.