Towards an optimized culture medium for the generation of mouse induced pluripotent stem cells

Generation of induced pluripotent stem cells from somatic cells using defined factors has potential relevant applications in regenerative medicine and biology. However, this promising technology remains inefficient and time consuming. We have devised a serum free culture medium termed iSF1 that facilitates the generation of mouse induced pluripotent stem cells. This optimization of the culture medium is sensitive to the presence of Myc in the reprogramming factors. Moreover, we could reprogram meningeal cells using only two factors Oct4/Klf4. Therefore, iSF1 represents a basal medium that may be used for mechanistic studies and testing new reprogramming approaches.

A mesenchymal-to-epithelial transition initiates and is required for the nuclear reprogramming of mouse fibroblasts

Epithelial-to-mesenchymal transition (EMT) is a developmental process important for cell fate determination. Fibroblasts, a product of EMT, can be reset into induced pluripotent stem cells (iPSCs) via exogenous transcription factors but the underlying mechanism is unclear. Here we show that the generation of iPSCs from mouse fibroblasts requires a mesenchymal-to-epithelial transition (MET) orchestrated by suppressing pro-EMT signals from the culture medium and activating an epithelial program inside the cells. At the transcriptional level, Sox2/Oct4 suppress the EMT mediator Snail, c-Myc downregulates TGF-beta1 and TGF-beta receptor 2, and Klf4 induces epithelial genes including E-cadherin. Blocking MET impairs the reprogramming of fibroblasts whereas preventing EMT in epithelial cells cultured with serum can produce iPSCs without Klf4 and c-Myc. Our work not only establishes MET as a key cellular mechanism toward induced pluripotency, but also demonstrates iPSC generation as a cooperative process between the defined factors and the extracellular milieu. PAPERCLIP:

Hyperglycaemia confers resistance to chemotherapy on breast cancer cells: the role of fatty acid synthase

The prognosis for women with breast cancer is adversely affected by the comorbidities of obesity and diabetes mellitus (DM), which are conditions associated with elevated levels of circulating fatty acids, hyperglycaemia and hyperinsulinaemia. We investigated the effects of exposure of non-malignant and malignant human breast epithelial cells to elevated levels of fatty acids and glucose on their growth, survival and response to chemotherapeutic agents. We found that palmitate induced cell death in the non-malignant cells but not in the malignant cells, which was abrogated through the inhibition of ceramide production and by oleate but not by IGF1. Fatty acid synthase (FAS) is responsible for the de novo synthesis of fatty acids from sugars, and is over-expressed in many epithelial cancers. Abundance of FAS was higher in malignant cells than in non-malignant cells, and was up-regulated by IGF1 in both cell types. IGF-induced growth of non-malignant cells was unaffected by suppression of FAS expression, whereas that of malignant cells was blocked as was their resistance to palmitate-induced cell death. Palmitate did not affect cell proliferation, whereas oleate promoted the growth of non-malignant cells but had the opposite effect, that is, inhibition of IGF1-induced growth of malignant cells. However, when the phosphatidylinositol 3-kinase pathway was inhibited, oleate enhanced IGF1-induced growth in both cell types. Hyperglycaemia conferred resistance on malignant cells, but not on non-malignant cells, to chemotherapy-induced cell death. This resistance was overcome by inhibiting FAS or ceramide production. Understanding the mechanisms involved in the associations between obesity, DM and breast cancer may lead to more effective treatment regimens and new therapeutic targets.

Aptamer-nanoparticle strip biosensor for sensitive detection of cancer cells

We report an aptamer-nanoparticle strip biosensor (ANSB) for the rapid, specific, sensitive, and low-cost detection of circulating cancer cells. Known for their high specificity and affinity, aptamers were first selected from live cells by the cell-SELEX (systematic evolution of ligands by exponential enrichment) process. When next combined with the unique optical properties of gold nanoparticles (Au-NPs), ANSBs were prepared on a lateral flow device. Ramos cells were used as a model target cell to demonstrate proof of principle. Under optimal conditions, the ANSB was capable of detecting a minimum of 4000 Ramos cells without instrumentation (visual judgment) and 800 Ramos cells with a portable strip reader within 15 min. Importantly, ANSB has successfully detected Ramos cells in human blood, thus providing a rapid, sensitive, and low-cost quantitative tool for the detection of circulating cancer cells. ANSB therefore shows great promise for in-field and point-of-care cancer diagnosis and therapy.

Generation of human induced pluripotent stem cells from umbilical cord matrix and amniotic membrane mesenchymal cells

The umbilical cord and placenta are extra-embryonic tissues of particular interest for regenerative medicine. They share an early developmental origin and are a source of vast amounts of cells with multilineage differentiation potential that are poorly immunogenic and without controversy. Moreover, these cells are likely exempt from incorporated mutations when compared with juvenile or adult donor cells such as skin fibroblasts or keratinocytes. Here we report the efficient generation of induced pluripotent stem cells (iPSCs) from mesenchymal cells of the umbilical cord matrix (up to 0.4% of the cells became reprogrammed) and the placental amniotic membrane (up to 0.1%) using exogenous factors and a chemical mixture. iPSCs from these 2 tissues homogeneously showed human embryonic stem cell (hESC)-like characteristics including morphology, positive staining for alkaline phosphatase, normal karyotype, and expression of hESC-like markers including Nanog, Rex1, Oct4, TRA-1-60, TRA-1-80, SSEA-3, and SSEA-4. Selected clones also formed embryonic bodies and teratomas containing derivatives of the 3 germ layers, and could as well be readily differentiated into functional motor neurons. Among other things, our cell lines may prove useful for comparisons between iPSCs derived from multiple tissues regarding the extent of the epigenetic reprogramming, differentiation ability, stability of the resulting lineages, and the risk of associated abnormalities.

Invasion of human coronary artery endothelial cells by Streptococcus mutans OMZ175

INTRODUCTION

Dissemination of oral bacteria into the bloodstream has been associated with eating, oral hygiene, and dental procedures; including tooth extraction, endodontic treatment, and periodontal surgery. Recently, studies identified Streptococcus mutans, the primary etiological agent of dental caries, as the most prevalent bacterial species found in clinical samples from patients who underwent heart valve and atheromatous plaque surgery.

METHODS

By using antibiotic protection assays, we tested the capacity of 14 strains of S. mutans to invade primary human coronary artery endothelial cells (HCAEC).

RESULTS

Serotype e strain B14 and serotype f strain OMZ175 of S. mutans were able to efficiently invade HCAEC. Among the tested strains, serotype f S. mutans OMZ175 was the most invasive, whereas strains of serotype c S. mutans, the most prevalent serotype in dental plaque, were not invasive. Based on its high invasion rate, we further investigated the invasive properties of serotype f OMZ175. Using transmission electron microscopy and antibiotic protection assays we demonstrate that S. mutans OMZ175 is capable of attaching to the HCAEC surface, entering the cells and surviving in HCAEC for at least 29 h.

DISCUSSION

Our findings highlight a potential role for S. mutans in the pathogenesis of certain cardiovascular diseases.

Molecular beacon-functionalized gold nanoparticles as probes in dry-reagent strip biosensor for DNA analysis

The highly specific molecule recognition properties of molecular beacons (MB) are combined with the unique optical properties of gold nanoparticles (Au-NPs) for the development of a dry-reagent strip-type nucleic acid biosensor (DSNAB) that enables sensitive and low-cost detection of nucleic acid samples within 15 min.

Amygdala protein kinase C epsilon controls alcohol consumption

Alcoholism is a progressive disorder that involves the amygdala. Mice lacking protein kinase C epsilon (PKCepsilon) show reduced ethanol consumption, sensitivity and reward. We therefore investigated whether PKCepsilon signaling in the amygdala is involved in ethanol consumption. Local knockdown of PKCepsilon in the amygdala reduced ethanol consumption and preference in a limited-access paradigm. Further, mice that are heterozygous for the PKCepsilon allele consume less ethanol compared with wild-type mice in this paradigm. These mice have a >50% reduction in the abundance of PKCepsilon in the amygdala compared with wild-type mice. We conclude that amygdala PKCepsilon is important for ethanol consumption in mice.

Mouse meningiocytes express Sox2 and yield high efficiency of chimeras after nuclear reprogramming with exogenous factors

Induced pluripotent stem cell technology, also termed iPS, is an emerging approach to reprogram cells into an embryonic stem cell-like state by viral transduction with defined combinations of factors. iPS cells share most characteristics of embryonic stem cells, counting pluripotency and self-renewal, and have so far been obtained from mouse and humans, including patients with genetic diseases. Remarkably, autologous transplantation of cell lineages derived from iPS cells will eliminate the possibility of immunological rejection, as well as current ethical issues surrounding human embryonic stem cell research. However, before iPS can be used for clinical purposes, technical problems must be overcome. Among other considerations, full and homogeneous iPS reprogramming is an important prerequisite. However, despite the fact that cells from several mouse tissues can be successfully induced to iPS, the overall efficiency of chimera formation of these clones remains low even if selection for Oct4 or Nanog expression is applied. In this report, we demonstrate that cells from the mouse meningeal membranes express elevated levels of the embryonic master regulator Sox2 and are highly amenable to iPS. Meningeal iPS clones, generated without selection, are fully and homogeneously reprogrammed based on DNA methylation analysis and 100% chimera competent. Our results define a population of somatic cells that are ready to undergo iPS, thus highlighting a very attractive cell type for iPS research and application.

Expression and hormonal regulation of IL-11Ralpha in canine uterus during early pregnancy

Embryo implantation is critical for the successful establishment of pregnancy. Interleukin-11 (IL-11) is essential for adequate decidualization in the mouse and human via binding to the specific IL-11 receptor alpha (IL-11Ralpha). But the expression and regulation of IL-11 and IL-11Ralpha in the canine endometrium remain unknown. The aim of this study was to investigate the differential expression of IL-11Ralpha in canine uterus during early pregnancy and its regulation under different conditions by in situ hybridization. Interleukin-11Ralpha mRNA was mainly localized in glandular epithelium in canine uterus. There was a low level of IL-11Ralpha expression in the glandular epithelium on days 6, 12 and 17 of pregnancy. On day 20 of pregnancy when embryo implanted, IL-11Ralpha mRNA was highly expressed in the glandular epithelium surrounding the embryo, but not in the luminal epithelium and stroma. On day 23 of pregnancy, the expression of IL-11Ralpha mRNA maintained a constant level compared with the expression of day 20 and increased on day 28 of pregnancy. During the oestrous cycle, a high level of IL-11Ralpha mRNA expression was seen in the oestrous uterus. Progesterone slightly induced the expression of IL-11Ralpha mRNA in the ovariectomized canine uterus. These results suggest that IL-11Ralpha expression is closely related to canine implantation and up-regulated by progesterone.