Journal of Stem Cells最新文献

Adult tissues contain quiescent reservoirs of multipotent somatic stem cells and pluripotent embryonic-like stem cells (ELSCs). Credited with regenerative properties gold is used across both -contemporary and -ancient medicines. Here, we show that gold exerted these effects by enhancing the pool of pluripotent ELSC while improving their stemness. We used hESCs as an in-vitro model to understand if gold could enhance self-renewal and pluripotency. Swarna-bhasma (SB), an ancient Indian gold microparticulate (41.1 nm), preparation, reduced spontaneous-differentiation, improved self-renewal, pluripotency and proliferation of hESCs. Colloidal gold-nanoparticles (GNP) (15.59 nm) were tested to confirm that the observations were attributable to nanoparticulate-gold. SB and GNP exposure: maintained -stemness, -karyotypic stability, enhanced pluripotency till day-12, increased average colony-sizes, and reduced the number of autonomously-derived differentiated FGFR1 positive fibroblast-niche-cells/colony. Particulate-gold induced upregulation of FGFR1 and IGF2 expression, and decrease in IGF1 secretion indicates IGF1/2 mediated support for enhanced pluripotency and self-renewal in hESCs.

Lung cancer is the number one killer among all cancers and is estimated to kill over 170,000 individual in 2010 in the United States. However, little is understood about the role of tumor initiating cells in the lung cancer and whether these cells play a major role in initiation, drug resistance, and metastases of this disease. We have isolated lungospheres from tumors grown in mice and have critically examined proposed biomarkers of lung cancer stem cells such as ALDH, EpCAM, CD133/1, CD133/2, CD24, and CD38, using global gene expression, flow cytometric analysis, and quantitative real time PCR. We present evidences that the pattern of overexpression of ALDH and EpCAM, two widely discussed biomarkers of cancer stem cells, in the tumor generated by lung cancer stem cells in mice are different that could be an indicative of tumor aggressiveness. We propose, for the first time, that CD38 in combination with CD24 is a biomarkers for H460 derived lung cancer stem cells and could be used to elucidate the characteristics of these sub-population of cells. Our results demonstrate that the combination of CD24(Low/-)/CD38+ and overexpression of ALDH1 and EpCAM is the signature of enriched tumor initiating cells in H460 non-small cell lung cancer cell line. Our results propose H460-derived cancer stem cells as a well defined cell for future comprehensive analysis of putative lung cancer stem cells-like cells.

While human embryonic stem (hES) and induced pluripotent stem (hiPS) cells offer exciting prospects in the fields of regenerative medicine and developmental biology, efficient directed differentiation of these cells is still difficult. Neural induction protocols often include suspension culture or co-culture with other cell types, introducing heterogeneity and complicating analysis. In addition, expensive recombinant factors are often used over processes that take weeks to complete, making such experiments financially difficult. We have developed a fully adherent and feeder free neural differentiation protocol using small molecules such as dorsomorphin and common medium supplements. Using this protocol, we obtain >90% of cells developing into neural precursors, as measured by nestin staining. Neurons derived from these precursors are electrophysiologically active. After three weeks of terminal differentiation, we obtain functional neurons which fire high-amplitude action potentials upon depolarization. A subset of neurons also fires repetitive trains. This protocol offers a simpler and less expensive method for investigations involving the differentiation of neural precursors and neurons in culture.

Using mouse pluripotent teratocarcinoma PCC4azal cells and proliferating spleen lymphocytes we obtained a new type of hybrids, in which marker lymphocyte genes were suppressed, but expression the Oct-4 gene was not effected; the hybrid cells were able to differentiate to cardiomyocytes. In order to specify the environmental factors which may affect the genetic stability and other hybrid properties, we analyzed the total chromosome number and differentiation potencies of hybrids respectively to conditions of their cultivation. Particular attention was paid to the number and transcription activity of chromosomal nucleolus organizing regions (NORs), which harbor the most actively transcribed - ribosomal - genes. The results showed that the hybrids obtained are characterized by a relatively stable chromosome number which diminished less than in 5% during 27 passages. However, a long-term cultivation of hybrid cells in non-selective conditions resulted in preferential elimination of some NO- chromosomes, whereas the number of active NORs per cell was increased due to activation of latent NORs. On the contrary, in selective conditions, i.e. in the presence of hypoxantine, aminopterin and thymidine, the total number of NOR-bearing chromosomes was not changed, but a partial inactivation of remaining NORs was observed. The higher number of active NORs directly correlated with the capability of hybrid cells for differentiation to cardiomyocytes.

The idea of growing human cells in vitro to yield a renewable source of cells for transplantation has captured the imagination of scientists for many years. The derivation of human embryonic stem cells (hESC) represented a major milestone in achieving this goal. hESC are pluripotent and can proliferate in vitro indefinitely, rendering them an ideal source for cell replacement therapy. Moreover, recent advances in reprogramming somatic cells into induced pluripotent stem cells (iPS cells) have enabled us to unravel some of the key master regulators of stem cell pluripotency. By integrating recent findings of molecular mechanism involved in maintenance of these different pluripotent stem cell types, we aim to present a global picture of how extracellular signals, intracellular signal transduction pathways and transcriptional networks cooperate together to determine the cell fate of pluripotent stem cells. Unraveling the signaling networks that control stem cell pluripotency will be helpful in deriving novel methods to maintain these pluripotent stem cells in vitro.

Pluripotent cells of the early embryo originate all types of somatic cells and germ cells of adult organism. Pluripotent stem cell lines were derived from mammalian embryos and adult tissues using different techniques and from different sources--inner cell mass of the blastocyst, primordial germ cells, parthenogenetic oocytes, and mature spermatogonia--as well as by transgenic modification of various adult somatic cells. Despite different origin, all pluripotent stem cell lines demonstrate considerable similarity of the major biological properties: unlimited self-renewal and differentiation into various somatic and germ cells in vitro and in vivo, similar gene expression profiles, and similar cell cycle structure. Their malignant counterpart embryonal teratocarcinoma stem cell lines have restricted developmental potentials caused by genetic disturbances that result in deregulation of proliferation and differentiation balance. Numerous studies on the stability of different pluripotent stem cell lines demonstrated that, irrespective of their origin, long-term in vitro cultivation leads to the accumulation of chromosomal and gene mutations as well as epigenetic changes that can cause oncogenic transformation of cells. Our research of signaling pathways and pattern of specific gene expression in pluripotent stem cells and teratocarcinoma cells is focused on discovery of fundamental mechanisms that regulate normal development of pluripotent cells into different lineages and are disrupted in cancer initiating cells. Analysis gene expression profiles, differentiation potentials and cell cycle of normal and mutant pluripotent stem cells provide new data to search molecular targets to eliminate malignant cells in tumors.

The recent scientific development using stem or other differentiated cells has generated great hopes for treatment of various diseases. Major thrust has been given to formulate country specific laws and regulations considering international guidelines to conduct research and clinical applications of "Cell Based Therapy" (CBT) all over the world. Attempts have made in this review to discuss the current policies that are practiced by various countries in the areas related to CBT with special emphasis on CBT related research and development in India. The two major funding agencies of Government of India e.g. Department of Biotechnology (DBT) and Indian Council of Medical Research (ICMR), have jointly formulated the "Guidelines for Stem Cell Research and Therapy" in 2007 which requires update and revision. Based on the review of the current world scenario of CBT research and development, suggestions have been made for the development of a new CBT policy that will help in progress of research and patient treatment in India.

Proviral expression of early development genes Oct4 and Sox2, in concert with cMyc and Klf4 or Nanog and Lin28, can induce differentiated cells to adopt morphological and functional characteristics of pluripotency indistinguishable from embryonic stem cells. Termed induced pluripotent stem (iPS) cells, in mice the pluripotency of these cells was confirmed by altered gene/surface antigen expression, remodeling of the epigenome, ability to contribute to embryonic lineages following blastocyst injection and commitment to all three germ layers in teratomas and liveborn chimeras. Importantly, in vitro directed differentiation of iPS cells yield cells capable of treating mouse models of humanized disease. Despite these impressive results, iPS cell conversion is frustratingly inefficient. Also, the unpredictable and random mutagenesis imposed on the host cell genome, inherent with integrative viral methodologies, continues to hamper use of these cells in a therapeutic setting. This has initiated exploration of non-integrating strategies for generating iPS cells. Here, we review mechanisms that drive conversion of somatic cells to iPS cells and the strategies adopted to circumvent integrative viral strategies. Finally, we discuss practical, ethical and legal considerations that require addressing before iPS cells can realize their potential as patient-specific cells for treatment of degenerative disease.

Tendons and ligaments are frequently injured. Due to their relatively avascular nature, repair is slow and often incomplete. Stem cells offer a new approach to augment healing of native tissues, as well as providing materials to surgically replace injured structures that are beyond repair. Here we discuss the various roles of stem cells in natural repair processes compared to engineered tissues to assist healing or replace tissues.

Apoptosis, proliferation and differentiation are balanced molecular processes which may alter their pattern during environmental insults. Arsenic is an environmental pollutant, ranks 20(th) in abundance in the earth crust, 14(th) in sea water and 12(th) in the human body. Millions of people worldwide are chronically exposed to arsenic often due to naturally occurring arsenic in ground water. Hematopoietic stem cells within the bone marrow are the source of all haematopoietic cell lineages and are essential for tissue development throughout the life. In this experimental study, we have evaluated the impact of arsenic, on blood and blood forming cells by the changes in their cellular morphology, immune functional capacity, alteration of bone marrow CD34 positive stem/progenitors and changes in the phenotype of Sca-1, c-Kit dual positive primitive stem cell population. The study revealed that arsenic has a significant effect on bone marrow and hematopoietic stem cells, their immune capacity and upregulation of death process, all indicative of impairment in differentiation suggesting presence of deregulation in their precursors by arsenic toxicity.