Showing papers on "Neurosphere published in 1988"

Cell lineage analysis reveals multipotency of some avian neural crest cells.

Abstract: A major question in developmental biology is how precursor cells give rise to diverse sets of differentiated cell types. In most systems, it remains unclear whether the precursors can form many or all cell types (multipotent or totipotent), or only a single cell type (predetermined). The question of cell lineage is central to the neural crest because it gives rise to numerous and diverse derivatives including peripheral neurons, glial and Schwann cells, pigment cells, and cartilage. Although the sets of derivatives arising from different populations of neural crest cells have been well-documented, relatively little is known about the developmental potentials of individual neural crest cells. We have iontophoretically microinjected the vital dye, lysinated rhodamine dextran (LRD) into individual dorsal neural tube cells to mark unambiguously their descendants. Many of the resulting labelled clones consisted of multiple cell types, as judged by both their location and morphology. Cells as diverse as sensory neurons, presumptive pigment cells, ganglionic supportive cells, adrenomedullary cells and neural tube cells were found within individual clones. Our results indicate that at least some neural crest cells are multipotent before their departure from the neural tube.

Epithelial stem cells in vivo.

Abstract: Summary Cellular topography within the highly polarized surface epithelia can be used to identify the location of the stem cells. In some instances, this can be quite precise and allows the characteristics of stem cells to be studied. Our current knowledge of the stem cell population in murine epidermis and small intestinal crypts is reviewed. In the epidermis, the stem cells would appear to make up about 10 % of the basal layer and are distributed towards the centre of the basal layer component of the epidermal proliferative unit. These cells have a long cell cycle and are probably the same cells that retain both tritiated thymidine and radioactively labelled carcinogens for long periods of time. This label retention permits the labelling of the putative stem cell compartment. Over recent years, there has been an accumulation of information indicating various types of heterogeneity within the basal layer, much of which can be interpreted in relation to cellular hierarchies. In the small intestine, cell positions can be fairly precisely identified and the stem cell zone identified. Complex modelling of a wide range of cell kinetic experiments suggests that each crypt contains between 4 and 16 steady state functional stem cells. Radiobiological experiments suggest that up to 32 cells may be capable of clonal regeneration. The repopulation of the clonogenic cell compartment has been determined and the doubling time measured to be 19.7 h. Such studies should throw further light on the behaviour of stem cells and identify the timing of periods of increased and decreased cell proliferation (activation and suppression of controls).

Specific effects of nerve growth factor on the differentiation pattern of mouse embryonic stem cells in vitro.

Abstract: The effect of nerve growth factor (NGF) on the differentiation pattern of pluripotent undifferentiated mouse embryonic stem cells (ESC) was studied. Morphological analysis of differentiating stem cells and histochemical silver-staining analysis of embryonic carcinoma (P19S1801A1) and embryonic stem cells (ESC-BLC 6) permitted the demonstration of nerve cell differentiation. NGF treatment resulted in an accelerated appearance of neuron-like cells in differentiating embryoid bodies of ESC line BLC 6. By use of the silver-staining test NGF dependent induction of nerve cell lineage was demonstrated. The presented embryonic stem cell model allows to study the time course of differentiation and induction of a special cell lineage of undifferentiated embryonic stem cells by growth factors.

Enriched mouse hematopoietic stem cells and progenitor cells in response to defined growth factors

Abstract: Three distinct hematopoietic populations derived from normal bone marrow were analyzed for their response to defined growth factors. The Thy-1loT- B- G- M-population, composing 0.2% of bone marrow, is 370- fold enriched for pluripotent hematopoietic stem cells. The two other populations, the Thy-1- T- B- G- M- and the predominantly mature Thy-1+ T+ B+ G+ M+ cells, lack stem cells. Thy-1loT- B- G- M- cells respond with a frequency of one in seven cells to IL-3 in an in vitro CFU-C assay, and give rise to many mixed colonies as expected from an early multipotent or pluripotent progenitor. The Thy-1- T- B- G- M- population also contains progenitor cells which responded to IL-3. However, colonies derived from Thy-1- T- B- G- M- cells are almost exclusively restricted to the macrophage/granulocyte lineages. This indicates that IL-3 can stimulate at least two distinct clonogenic early progenitor cells in normal bone marrow: multipotent Thy-1loT- B- G- M- cells and restricted Thy-1- T- B- G- M- cells. Thy-1loT- B- G- M- cells could not be stimulated by macrophage colony-stimulating factor (M-CSF), granulocyte CSF (G-CSF) or IL-5 (Eosinophil-CSF). The hematopoietic precursors that react to these factors are enriched in the Thy-1- T- G- B- M- population. Thus, multipotent and restricted progenitors can be separated on the basis of the expression of the cell surface antigen Thy-1.