Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Stemness”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed2003

An in-vitro investigation of the CPS-Plus femoral stem: influence of the proximal centraliser on cement pressurisation during stem insertion.

The CPS-Plus stem is designed for use with a proximal and distal stem centraliser. This in-vitro study examined the cement pressurisation achieved during insertion of the CPS-Plus femoral stem into a model femur. Cement pressures were measured at proximal, mid and distal stem levels. Pressures were recorded during insertion of the CPS-Plus stem with both proximal and distal centralisers and compared with those achieved when only a distal centraliser was used with digital occlusion of the proximal femur. The CPS-Plus with a proximal centraliser generated significantly greater cement pressures than the CPS-Plus without a proximal centraliser at proximal and mid-stem regions. The use of a proximal stem centraliser may improve the cement-bone interdigitation and shear strength at the cement-bone interface, particularly in the region of the proximal femur.

Biomechanical Phenomena↗
PubMed1997

The Sesbania Root Symbionts Sinorhizobium saheli and S. teranga bv. sesbaniae Can Form Stem Nodules on Sesbania rostrata, although They Are Less Adapted to Stem Nodulation than Azorhizobium caulinodans.

Sesbania species can establish symbiotic interactions with rhizobia from two taxonomically distant genera, including the Sesbania rostrata stem-nodulating Azorhizobium sp. and Azorhizobium caulinodans and the newly described Sinorhizobium saheli and Sinorhizobium teranga bv. sesbaniae, isolated from the roots of various Sesbania species. A collection of strains from both groups were analyzed for their symbiotic properties with different Sesbania species. S. saheli and S. teranga bv. sesbaniae strains were found to effectively stem nodulate Sesbania rostrata, showing that stem nodulation is not restricted to Azorhizobium. Sinorhizobia and azorhizobia, however, exhibited clear differences in other aspects of symbiosis. Unlike Azorhizobium, S. teranga bv. sesbaniae and S. saheli did not induce effective stem nodules on plants previously inoculated on the roots, although stem nodulation was arrested at different stages. For Sesbania rostrata root nodulation, Sinorhizobium appeared more sensitive than Azorhizobium to the presence of combined nitrogen. S. saheli and S. teranga bv. sesbaniae were effective symbionts with all Sesbania species tested, while Azorhizobium strains fixed nitrogen only in symbiosis with Sesbania rostrata. In a simple screening test, S. saheli and S. teranga bv. sesbaniae were incapable of asymbiotic nitrogenase activity. Thus, Azorhizobium can easily be distinguished from Sinorhizobium among Sesbania symbionts on the basis of symbiotic and free-living nitrogen fixation. The ability of Azorhizobium to overcome the systemic plant control appears to be a stem adaptation function. This last property, together with its host-specific symbiotic nitrogen fixation, makes Azorhizobium highly specialized for stem nodulation of the aquatic legume Sesbania rostrata.

Journal Article↗
PubMed2002

RNA destabilization by the granulocyte colony-stimulating factor stem-loop destabilizing element involves a single stem-loop that promotes deadenylation.

Granulocyte colony-stimulating factor (G-CSF) mRNA contains two distinct types of cis-acting mRNA destabilizing elements in the 3'-untranslated region. In addition to several copies of the AU-rich element the G-CSF mRNA also contains a destabilizing region that includes several predicted stem-loop structures. We report here that the destabilizing activity resides in a single stem-loop structure within this region. A consensus sequence for the active structure has been derived by site-directed mutagenesis, revealing that a three-base loop of sequence YAU and unpaired bases either side of the stem contribute to the activity. The helical nature of the stem is essential and the stem must be less than 11 bp in length, but the destabilizing activity is relatively insensitive to the sequence within the helix. The stem-loop increases the rate of mRNA deadenylation, most likely by enhancing the processivity of the deadenylation reaction. A protein that binds the stem-loop, but not an inactive mutant form, has been detected in cytoplasmic lysates.

3' Untranslated Regions↗
PubMed2001

Distortion of teatree stems by twine as a means to determine the number of years that the stems have been used to support cannabis plants.

In New Zealand, stems of teatree (Kunzea/Leptospermum) growing around illicit cannabis plots have been used to anchor lengths of twine running through the plots to hold cannabis plants upright. Forensic examinations of distortions of teatree stems caused by the twine have been carried out to determine when the twine had been first tied around the stems, in order to estimate the number of years that plots have been in operation. In this experiment, baling twine was tied around stems of a teatree (Kunzea ericoides) and the effect monitored for a period of three years. Varying degrees of stem distortion occurred during the first year, caused initially by expansion of callus (a wound tissue) rather than constriction of the growth (annual) rings of the xylem. Although this callus has a type of growth ring, these are not annual, therefore cannot be used to determine the number of years that stems have had twine attached. Xylem growth rings of the teatree in this experiment were not restricted until the third year. Distortion of teatree stems allows the determination of a minimum (not absolute) number of years that twine has been attached.

Journal Article↗
PubMed2004

Clonogenic analysis reveals reserve stem cells in postnatal mammals. II. Pluripotent epiblastic-like stem cells.

Undifferentiated cells have been identified in the prenatal blastocyst, inner cell mass, and gonadal ridges of rodents and primates, including humans. After isolation these cells express molecular and immunological markers for embryonic cells, capabilities for extended self-renewal, and telomerase activity. When allowed to differentiate, embryonic stem cells express phenotypic markers for tissues of ectodermal, mesodermal, and endodermal origin. When implanted in vivo, undifferentiated noninduced embryonic stem cells formed teratomas. In this report we describe a cell clone isolated from postnatal rat skeletal muscle and derived by repetitive single-cell clonogenic analysis. In the undifferentiated state it consists of very small cells having a high ratio of nucleus to cytoplasm. The clone expresses molecular and immunological markers for embryonic stem cells. It exhibits telomerase activity, which is consistent with its extended capability for self-renewal. When induced to differentiate, it expressed phenotypic markers for tissues of ectodermal, mesodermal, and endodermal origin. The clone was designated as a postnatal pluripotent epiblastic-like stem cell (PPELSC). The undifferentiated clone was transfected with a genomic marker and assayed for alterations in stem cell characteristics. No alterations were noted. The labeled clone, when implanted into heart after injury, incorporated into myocardial tissues undergoing repair. The labeled clone was subjected to directed lineage induction in vitro, resulting in the formation of islet-like structures (ILSs) that secreted insulin in response to a glucose challenge. This study suggests that embryonic-like stem cells are retained within postnatal mammals and have the potential for use in gene therapy and tissue engineering.

Animals↗
PubMed2025

A Protocol for Detecting DNA Methylation Changes at CpG Sites of Stemness-Related Genes in Aging Stem Cells.

Aging adversely affects the self-renewal and differentiation capabilities of stem cells, which impairs tissue regeneration as well as the homeostasis. Epigenetic mechanisms, specifically DNA methylation, play a key role in the maintenance of pluripotency in stem cells and regulation of pluripotency-related gene expression. Age-related modifications in methylation patterns could influence the expression of genes critical for stem cell potency maintenance, including transcription factors Nanog and Sox2. The following chapter describes a step-by-step bisulfite sequencing protocol for detection of methylation changes in the aging stem cells and provides valuable insights into the stem cells epigenetic profile. Further, the methodology describes the steps of genomic DNA extraction, bisulfite conversion, real-time PCR amplification, and sequencing for an in-depth view of the epigenetic profile derived from aging stem cells.

DNA Methylation↗
PubMed2006

Bone marrow derived mesenchymal stem cells from chronic myeloid leukemia t(9;22) patients are devoid of Philadelphia chromosome and support cord blood stem cell expansion.

Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder of hematopoietic stem cells. It is characterized at cytogenetic level by the Philadelphia (Ph) chromosome and at the molecular level by the BCR/ABL gene rearrangement. Bone marrow derived mesenchymal stem cells (MSCs) are also pluripotent stem cells that can differentiate into several mesenchymal tissues. To date, no study has been performed to characterize whether MSCs from CML harbor the abnormal Ph chromosome similar to CML bone marrow cells. We isolated and characterized MSCs from diagnostic marrow samples (n=11) and showed that MSCs can be readily isolated from CML marrow and exhibit major expansion potential as well as intact osteogenic differentiation ability. Moreover, they do not harbor the Ph chromosome confirmed by fluorescence in situ hybridization (FISH) and reverse transcriptase polymerase chain reaction (RT-PCR). Thus, we demonstrated that CML marrow is an abundant source of MSCs appearing through both FISH and RT-PCR not to be involved by the malignant process of CML. Furthermore, these MSCs from a CML patient could support in vitro cord blood expansion as those MSCs from a normal donor. Since MSCs are able to support engraftment of hematopoietic stem cells in stem cell transplantation (SCT) as well as suppress alloreactive T cells causing graft-versus-host disease, this current report thus provides evidence that in a SCT setting of CML patients, autologous MSCs could be a source of stem cell support in future cell therapy applications.

Adolescent↗
PubMed2004

Murine marrow cellularity and the concept of stem cell competition: geographic and quantitative determinants in stem cell biology.

In unperturbed mice, the marrow cell numbers correlate with the stem cell numbers. High levels of long-term marrow engraftment are obtained with infusion of high levels of marrow cells in untreated mice. To address the issue of stem cell competition vs 'opening space', knowledge of total murine marrow cellularity and distribution of stem and progenitor cells are necessary. We determined these parameters in different mouse strains. Total cellularity in BALB/c mice was 530+/-20 million cells; stable from 8 weeks to 1 year of age. C57BL/6J mice had 466+/-48 million marrow cells. Using these data, theoretical models of infused marrow (40 million cells) replacing or adding to host marrow give chimerism values of 7.5 and 7.0%, respectively; the observed 8-week engraftment of 40 million male BALB/c marrow cells into female hosts (72 mice) gave a value of 6.91+/-0.4%. This indicates that syngeneic engraftment is determined by stem cell competition. Our studies demonstrate that most marrow cells, progenitors and engraftable stem cells are in the spine. There was increased concentration of progenitors in the spine. Total marrow harvest for stem cell purification and other experimental purposes was both mouse and cost efficient with over a four-fold decrease in animal use and a financial saving.

Animals↗
PubMed2005

Embryonic stem cell-derived hematopoietic stem cells.

Despite two decades of studies documenting the in vitro blood-forming potential of murine embryonic stem cells (ESCs), achieving stable long-term blood engraftment of ESC-derived hematopoietic stem cells in irradiated mice has proven difficult. We have exploited the Cdx-Hox pathway, a genetic program important for blood development, to enhance the differentiation of ESCs along the hematopoietic lineage. Using an embryonic stem cell line engineered with tetracycline-inducible Cdx4, we demonstrate that ectopic Cdx4 expression promotes hematopoietic mesoderm specification, increases hematopoietic progenitor formation, and, together with HoxB4, enhances multilineage hematopoietic engraftment of lethally irradiated adult mice. Clonal analysis of retroviral integration sites confirms a common stem cell origin of lymphoid and myeloid populations in engrafted primary and secondary mice. These data document the cardinal stem cell features of self-renewal and multilineage differentiation of ESC-derived hematopoietic stem cells.

Animals↗
PubMed2002

The changes of serum leptin and soluble leptin receptor levels in patients undergoing mobilization of peripheral blood stem cells before autologous stem cells transplantation.

BACKGROUND AND OBJECTIVES: Leptin was demonstrated to stimulate the proliferation of hematopoietic stem cells in vitro, but there is scarce information concerning serum leptin levels in patients with hematological diseases. The aim of our study was to measure serum leptin levels in patients undergoing mobilization of peripheral blood stem cells (PBSC) before autologous stem cell transplantation (ASCT). DESIGN AND METHODS: Eighteen patients indicated for ASCT were included in the study. The blood samples were obtained before the initiation of mobilization chemotherapy, at the phase of maximal leukopenia and on the second day of stem cell harvest. Serum leptin levels, soluble leptin receptor, cortisol, insulin, tumor necrosis factor alpha (TNFalpha), and interleukin-1 receptor antagonist (IL-1ra) levels were measured in the withdrawn samples. RESULTS: The basal values of parameters measured except for higher levels of IL-1ra in mobilized group did not differ significantly from those of a control group of healthy subjects. Serum leptin levels decreased significantly at the leukopenia phase and remained suppressed in the stem cell harvest phase (means +/- standard error means (SEM): 12.2 +/- 2.4 vs. 7.7 +/- 1.5 vs. 9.3 +/- 1.9 ng mL(-1)). No significant changes were found in soluble leptin receptor, insulin, cortisol, and TNFalpha levels throughout three measurements, while IL-1ra levels increased significantly in the SC harvest phase compared to the previous two measurements. INTERPRETATION AND CONCLUSIONS: As no metabolic variations explaining suppressed leptin levels were found, this suppression could be the result either of G-CSF administration or increased leptin consumption by activated stem cells.

Adult↗
PubMed2005

Clonal amniotic fluid-derived stem cells express characteristics of both mesenchymal and neural stem cells.

Recent evidence has shown that amniotic fluid may be a novel source of fetal stem cells for therapeutic transplantation. We previously developed a two-stage culture protocol to isolate a population of amniotic fluid-derived mesenchymal stem cells (AFMSCs) from second-trimester amniocentesis. AFMSCs maintain the capacity to differentiate into multiple mesenchymal lineages and neuron-like cells. It is unclear whether amniotic fluid contains heterogeneous populations of stem cells or a subpopulation of primitive stem cells that are similar to marrow stromal cells showing the behavior of neural progenitors. In this study, we showed a subpopulation of amniotic fluid-derived stem cells (AF-SCs) at the single-cell level by limiting dilution. We found that NANOG- and POU5F1 (also known as OCT4)-expressing cells still existed in the expanded single cell-derived AF-SCs. Aside from the common mesenchymal characteristics, these clonal AF-SCs also exhibit multiple phenotypes of neural-derived cells such as NES, TUBB3, NEFH, NEUNA60, GALC, and GFAP expressions both before and after neural induction. Most importantly, HPLC analysis showed the evidence of dopamine release in the extract of dopaminergic-induced clonal AF-SCs. The results of this study suggest that besides being an easily accessible and expandable source of fetal stem cells, amniotic fluid will provide a promising source of neural progenitor cells that may be used in future cellular therapies for neurodegenerative diseases and nervous system injuries.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1995

The auditory brain stem response in patients with brain stem or cochlear pathology.

OBJECTIVE: The purpose of this study was to determine the value, based on true-positive and false-positive rates, of various auditory brain stem response (ABR) indices in discriminating patients with brain stem lesions from patients with cochlear lesions. DESIGN: A factorial design was used in this retrospective study. Receiver operating characteristics (ROC) curves were constructed to analyze the performance of 32 patients with brain stem lesions and 33 patients with cochlear involvement for the absolute latency of wave V; the I-III, III-V, and I-V interwave intervals; the interaural latency difference and the V/I amplitude ratio. Analyzed in the same manner were four combinations of ABR indices. RESULTS: Based on the ROC curves, the clinically most valuable index was the I-V interval, but overall the individual indices showed only moderate sensitivity to brain stem pathology. By combining several indices, the sensitivity to brain stem involvement was improved. However, as expected, the overall false-positive rate also increased. CONCLUSIONS: There is a diagnostic advantage to using more than one ABR index in evaluating patients suspected of having brain stem involvement.

Adolescent↗
PubMed2003

Stem cell plasticity: a new image of the bone marrow stem cell.

The central tenet of stem cell biology is that within tissues there reside stem cells with the capacity for both self-renewal and terminal differentiation to the multiple lineages of that tissue. Over the last few years, numerous studies have challenged this paradigm by showing that tissue stem cells can differentiate to unexpected cell lineages, suggesting an enormous plasticity of differentiation. The hematopoietic stem cell, which resides within bone marrow and gives rise to all blood cells, has been the focal point of these efforts. However, recent studies have disputed the notion of hematopoietic stem cell plasticity. In truth, stem cell plasticity, strictly defined, has yet to be rigorously proven. Both animal models to carefully address outstanding issues and pilot clinical trials to explore the therapeutic potential will be key elements to advance science for the benefit of patients.

Cell Differentiation↗
PubMed2000

Role of mesenchymal stem cells in hematopoietic stem cell transplantation.

Within the bone marrow stroma are multipotential cells which are capable of differentiation into a number of mesenchymal cell lineages. These cells, termed mesenchymal stem cells, have recently been identified and characterized in humans. Many studies indicate that the bone marrow stroma is damaged following bone marrow transplantation. Since the marrow stroma is critical for the maintenance of hematopoiesis, its ability to support hematopoiesis following stem cell transplantation may be impaired. Animal models suggest that the transplantation of healthy stromal elements, including mesenchymal stem cells, may enhance the ability of the bone marrow microenvironment to support hematopoiesis after stem cell transplantation. Here the authors review recent data that suggest that mesenchymal stem cells may possess therapeutic value not only for the repair of damaged mesenchymal tissues following hematopoietic stem cell transplantation, but also as potential vectors for the delivery of corrective genes.

Animals↗
PubMed2002

"Stemness": transcriptional profiling of embryonic and adult stem cells.

The transcriptional profiles of mouse embryonic, neural, and hematopoietic stem cells were compared to define a genetic program for stem cells. A total of 216 genes are enriched in all three types of stem cells, and several of these genes are clustered in the genome. When compared to differentiated cell types, stem cells express a significantly higher number of genes (represented by expressed sequence tags) whose functions are unknown. Embryonic and neural stem cells have many similarities at the transcriptional level. These results provide a foundation for a more detailed understanding of stem cell biology.

ATP-Binding Cassette Transporters↗
PubMed2004

Hematopoietic stem cell dose correlates with the speed of immune reconstitution after stem cell transplantation.

In the current study, we tested whether higher numbers of hematopoietic stem cells correlate with the speed of immune reconstitution in a congenic transplantation model (C57BL/Ka, CD45.1, Thy1.1-->C57BL/6, CD45.2, Thy1.2) using purified hematopoietic stem cells (c-Kit(+)Thy1.1(low)Lin(-/low)Sca-1(+)). There were 3 different doses of stem cells used (400, 1000, and 5000). Phenotypic analyses in peripheral blood and spleen demonstrated that higher numbers of infused stem cells are associated with more rapid regeneration of T cells (CD4(+), CD8(+), naive CD4(+), naive CD8(+)) and B cells at early time points. The numbers of T and B cells eventually became equivalent between different dose groups at late time points. Production of interleukin-2 and inter-feron-gamma per T cell was similar regardless of stem cell dose even when tested at the time when there were significant differences in peripheral T-cell counts. The improved immune recovery was attributed to a more rapid regeneration of donor-type immune cells. Higher numbers of total thymocytes and signal joint T-cell receptor excision circles were observed in the higher dose stem cell recipients, suggesting that accelerated regeneration of T cells was due to enhanced thymopoiesis.

Animals↗
PubMed2000

[A stem cell ... is stem cell?].

We are used to associate stem cells with renewable tissues such as blood, gut and skin. But some cells in the adult central nervous system have the capacity to generate new neurons and glial cells as well and as such, they are considered to be neural stem cell. Yet their ability to generate neurons and glia, and their presence in the central nervous system throughout life, suggests new, intriguing possibilities for recovery and repair after damage to the central nervous system--and unexpectedly, the regeneration of blood tissues. After transplantation into irradiated hosts, neural stem cells were found to produce a variety of blood cell types including myeloid and lymphoid cells as well as early hematopoietic cells. Therefore, the developmental potential of stem cells is not restricted to the differentiated elements of the tissue in which they reside. Multipotential stem cells can persist in an undifferentiated state, and depending on specific environmental conditions function as a stem cell for many different tissues.

Hematopoietic Stem Cells↗
PubMed1995

Long-term repopulation of irradiated mice with limiting numbers of purified hematopoietic stem cells: in vivo expansion of stem cell phenotype but not function.

Hematopoietic stem cells were isolated from normal adult mouse bone marrow based on surface antigen expression (Thy-1.1(low)Lin(neg)Ly-6A/E+) and further selected for low retention of rhodamine 123. This population of cells (Rh-123low) could mediate radioprotection and long-term (greater than 12 months) repopulation after transplantation of as few as 25 cells. Transfer of five genetically marked Rh-123low cells in the presence of 10(5) normal bone marrow cells resulted in reconstitution of peripheral blood by greater than 10% donor cells in 64% (30 of 47) of recipient mice. Of 46 animals surviving after 24 weeks, 10 had over 50% donor-derived cells in peripheral blood. Two general patterns of long-term reconstitution were observed: one in which many donor-derived cells were observed 5 to 6 weeks after reconstitution and another in which donor-derived cells were rare initially but expanded with time. This result suggests that two classes of long-term repopulating hematopoietic stem cells exist, differing in their ability to function early in the course of transplantation. Alternatively, distinct anatomic sites of engraftment may dictate these two outcomes from a single type of cell. As an approach to measure the extent of self-renewal by the injected cells, recipients of five or 200 stem cells were killed 8 to 13 months after the transplants, and Thy-1.1(low)Lin(neg)Ly-6A/E+ progeny of the original injected cells were isolated for a second transplant. While a numerical expansion of cells expressing the cell surface phenotype of stem cells was observed, along with activity in the colony-forming unit-spleen assay, the expanded cells were vastly inferior in radioprotection and long-term reconstitution assays when compared with cells freshly isolated from normal animals. This result demonstrates that in stem cell expansion experiments, cell surface antigen expression is not an appropriate indicator of stem cell function.

Animals↗