Neural Differentiation of Human and Nonhuman Primate ES Cells

Neural differentiation potential was readily observed when primate ES, or ES-like cells were first established in both monkey and hES cells, as well as in human EG cells and monkey parthenogenetic stem cells. However, the derivation of purified populations of neural progeny from hES cells required more systematic studies. A highly efficient protocol for the neural differentiation of hES cells was based on a modified multistep EB approach. ES cells are aggregated short-time ( 4 days) and...

Ducts

It is widely believed that adult pancreatic stem progenitor cells are located in the duct epithelium. Indeed, cells expressing b-cell markers (insulin, glut-2, pax6, isll, and HNF3b) can often be found embedded in or adjacent to adult ducts following an insult to the pancreas. Moreover, duct cell replication (as assessed by BrdU incorporation) is increased after such insults. In addition, adult duct preparations are claimed to be capable of endocrine differentiation in vitro (see later sections...

Adult Liver Stem Cells

Organization and Functions of Adult Mammalian Liver The liver consists of several separate lobes and represents about 2 of human and 5 of murine body weight. It is the only organ with two separate afferent blood supplies. The portal vein brings in venous blood rich in nutrients and hormones from the splanchnic bed (intestines and pancreas), and the hepatic artery provides oxygenated blood. Venous drainage is into the vena cava. The bile secreted by hepato-cytes is collected in a branched...

Recruiting Circulating Stem Cell Reserves

The relative scarcity of progenitor cells residing in the adult myocardium has prompted a search for a renewable source of circulating somatic progenitor cells that might home to the heart in response to damage. The presence of such cell populations has gained credibility from observations of sex-mismatched cardiac human transplants in which a female heart is transplanted into a male host. In these patients, the presence of the Y-chromosome marks host-derived cells in the transplanted heart....

Derivation Of Esderived Neurons

Spontaneous differentiation into neurons occurs rapidly upon neural induction of mouse ES cells. Neuronal subtype specification can be influenced by the mode of neuronal induction. This is particularly the case for RA induction protocols. The basic strategy for achieving neuronal subtype specification is based on mimicking patterning events that define AP and DV patterning events in vivo. Midbrain Dopaminergic Neurons Derivation of midbrain dopamine neurons from ES cells has been of particular...

Skeletal Muscle Stem Cells

In recent years, study of the muscle stem cell (MuSC) has been revitalized because of several provocative reports of potential plasticity of function within the heterogeneous MuSC population that can participate in processes ranging widely from hematopoiesis to osteogenesis, adipogenesis, and myogenesis. There are also reports suggesting that cells from the circulation and from the vasculature give rise to MuSCs and ultimately to skeletal muscle fibers. Here we discuss the identification and...

Insulinlike Growth Factor

Neurogenic effects of insulin-like growth factor (IGF) have been identified in cultures of embryonic neural stem cells as well as in vivo using transgenic models overexpressing or lacking specific IGF encoding genes. In proliferative cultures of embryonic precursors, insulin and IGFs promote the proliferation of neural stem cells and the acquisition of a neuronal phenotype. In mice and humans, disruption of the IGF-I gene is associated with profound retardation of brain growth. In contrast,...

Abnormal Dna Methylation Patterns In Clones

Considering the fundamental role of DNA methylation in development, it seems likely that any cloned embryo will need to recapitulate a functional pattern of epigenetic modifications to proceed through normal embryogenesis. Several research groups have investigated DNA methylation patterns in cloned embryos and reported finding abnormalities in DNA methy-lation. In cloned bovine embryos, satellite sequence methy-lation levels are closer to the donor cells than to control embryos. However,...

Bone Marrow To Other Cell Types

Some cell-type conversions using bone marrow-derived stem cells have been shown to occur across what was previously considered to be germ-line boundaries (i.e., mesoderm to endoderm). In this situation, it is not evident whether the cell must first become a different stem cell and then differentiate along a different pathway or if it directly transdifferentiates to another phenotype. However, some doubt has been cast on these observations, and it has been suggested that the result is caused by...

Dna Methylation During Normal Development

DNA methylation provides heritable information to the DNA that is not encoded in the nucleotide sequence. In higher eukaryotes, DNA methylation is the only covalent modification of the DNA. It occurs at position 5 of the pyrimidine ring of cytosines and is almost exclusively restricted to CpG din-ucleotides in somatic cells. In contrast, embryonic stem (ES) cells and early embryos seem to contain significant amounts of non-CpG methylation (mostly CpA). Currently, the functional role of this...

The Elusive Cardiac Stem Cell

The adult mammalian heart has long been considered a post-mitotic organ without an endogenous population of stem cells, which instead contain a relatively constant number of myocytes that cease to divide shortly after birth and remain constant into senescence. A long-standing view is that the inability of differentiated cardiac myocytes to reenter the cell cycle may present the ultimate impediment to the heart's regenerative capacity and may be responsible for the drastic effects of acute and...

Stem Cells in the Gastrointestinal Tract

Direkze, Nicholas A. Wright, and Mairi Brittan Turnover of the epithelial cell lineages within the gastrointestinal tract is a constant process, occurring every two to seven days under normal homeostasis and increasing after damage. This process is regulated by multipotent stem cells, which generate all gastrointestinal epithelial cell lineages and can regenerate whole intestinal crypts and gastric glands. The stem cells of the gastrointestinal tract are as yet...

Pancreatic Stem Cells

Pancreas Duct Cell Marker

From a clinical perspective, the pancreas is an important focus of stem cell research because it is an attractive target for cell replacement therapy. In type I diabetes, the insulin-producing b-cells that reside in the pancreatic islets of Langerhans are destroyed by autoimmune attack, and it is thought that self-renewing stem cells could provide an unlimited source of b-cells for transplantation. Such therapeutic efforts require the prospective isolation of stem cells, with the potential to...

Polycomb And Trithorax Groups

Polycomb Group (Pc-G) Silencing Genetic screens in Drosophila have identified many Poly-comb group (Pc-G) genes required for the proper expression of homeotic genes (Simon and Tamkun, 2002). Whereas gap and pair-rule gene products are required to establish homeotic gene expression, Pc-G factors are required for maintenance. Not unexpectedly, these distinct classes of regulatory factors act in concert. Gap and pair-rule genes encode DNA binding factors that bind to enhancers and promoters of...

Barretts Metaplasia

Barrett's metaplasia (or Barrett's esophagus, as it is sometimes called) is the clinical situation in which intestinal cells are found in the tissue of the lower end of the esophagus. In the strictest terms, it is the conversion of stratified squamous epithelium to columnar epithelium and is characterized by the presence in biopsy material of acid mucin-containing goblet cells. The importance of Barrett's metaplasia stems from the rise in apparent incidence of the disease and its risk associ...

Evolving Concepts of Regeneration

Stem Cells For Acne Scars

The limited restorative capacity of the adult mammalian heart has been attributed to the loss of cardiomyocyte versatility soon after birth. Emerging concepts of regeneration as an evolutionary variable are dramatically illustrated by the relatively robust proliferative capacity of the injured heart in other vertebrate species. The dramatic regeneration of urodele amphibian limb and lens extends to their robust repair of injured myocardium. Unlike their mammalian counterparts, adult newt...

Fgf2 And Knockout Serum Replacer

Amit et al. 2000 examined the use of different media to increase the cloning efficiency of HESC. This study describes conditions allowing the use of a serum-free medium for the propagation of HESC. Basal medium 80 DMEM no pyruvate, high glucose formulation , 1 mM glutamine, 0.1 mM b-mercaptoethanol, and 1 nonessential amino acids was supplemented with either 20 fetal calf serum or 20 Knockout Serum Replacer, with or without 4ng ml FGF-2. Knockout Serum Replacer is a proprietary serum...

B

Differentiating keratinocytes basal kpratinorytes Figure 5-3. A Schematic of the components of a hair follicle modifiec from Watt, 2001 . The follicular bulge asterisk has been proposed to act as a stem cell niche, which houses cells that can contribute to all the differentiated cell types involved in the formation of the hair follicle, including the outer root sheath, inner root sheath, and hair shaft. Stem cells within the bulge can also generate sebocytes and the cells that maintain the...

The Human Embryo

Trophoblast Stem Cells Pseudostratified

Human development during implantation and gastrulation is significantly different from that of the mouse. Briefly, the Figure 12-6. Tissue formation and movements during the gastrulation of the mouse embryo E6.5-E7.5 . Gastrulation begins with the formation of the primitive streak ps in the posterior side of the E6.5 embryo at the junction of the extraembryonic ectoderm ex and epiblast e A . As more cells ingress through the streak, it elongates toward the distal tip of the embryo, between...

Atpase Chromatinremodeling Complexes

In addition to enzymes that covalently modify histones, there is a second evolutionarily conserved mechanism that modulates chromatin structure, which is carried out by SWI SNF and a variety of other ATPase chromatin-remodeling complexes Narlikar et al., 2002 . SWI SNF does not possess significant DNA binding ability of its own but is recruited to promoters by sequence-specific transcription factors. The energy derived from ATP hydrolysis allows the complex to alter the conformation and...

How Cells Change Their Phenotype

Until recently, it was thought that once a cell had acquired a stable differentiated state, it could not change its phenotype. We now know this is not the case, and over the past few years a plethora of well-documented examples have been presented whereby already differentiated cells or tissue-specific stem cells have been shown to alter their phenotype to express functional characteristics of a different tissue. In this chapter, we examine evidence for these examples, comment on the underlying...

Germline Stem Cell Niche In The Drosophila Ovary

Drosophila Germarium

The adult Drosophila ovary consists of approximately 15 ovarioles, each with a specialized structure, the germarium, at the most anterior tip Figure 5-1A . Two to three GSCs lie at the anterior tip of the germarium, close to several groups of differentiated somatic cell types, including the terminal filament, cap cells, and inner germarial sheath cells Figure 5-1A, Figure 5-1B . When a female GSC divides, the daughter cell that lies closer to the terminal filament and cap cells retains stem...