P1-04-02: In Vitro Qualification and Quantification of Murine Mammary Stem/Progenitor Cells

Increasing evidence suggest that tumors with a cell origin of more basal or stem-like sources are often highly metastatic and associated with poor prognosis. Identification of the cell of origin thus has important implications for development of new preventive and therapeutic approaches. To identifying the cells of origin of various breast cancers, understanding the normal cellular hierarchy within the breast tissue is an important prerequisite. However, current understanding of normal mammary stem/progenitor cell is limited due to the lack of a robust in vitro assay. The newly developed cell surface markers (CD24+CD49fhi) can only be used for low percent of enrichment. The only gold standard assay for functional evaluation of stem cell property is the in vivo transplantation of cleared mammary fat pad assay, yet this assay is expensive, time consuming, and requires highly trained skills, and thus cannot be used routinely for experiments. The goal of our study is thus to develop a robust in vitro assay to qualify and quantify murine mammary stem/progenitor cells. Our rationale lies on our recent findings of in vitro study of different fractions of murine stem/progenitor cells. When we use isolated primary epithelial cells for in vitro mammosphere formation, we found that stem cell enriched fraction and progenitor cell enriched fraction both formed very small mammospheres (≤ 50 μm) and these spheres appear to be of clonal origin (one cell gives rise to one sphere). When we plated these small spheres into 3D extracellular matrix for colony formation, however, they gave rise to two distinct structures: stem-enriched fraction generated predominately solid structure while progenitor-enriched fraction is dominated by hollow structures. Previous studies have linked the solid structure to the basal/myoepithelial lineage and the hollow structure to the luminal lineage. We thus suspected that the small mammospheres derived from the stem or progenitor enriched fractions could be originated from single stem or progenitor cell, and the number of spheres could indicate the number of original stem/progenitor cells within these enriched fractions. Subsequent in vivo transplantation with single sphere or single solid structure cultured in 3D extracellular matrix derived from green fluorescent protein transgenic mice proved that single sphere or 3D solid structure can repopulate the gland-free mammary fat pad. To conclude, the in vitro mammosphere formation in combination with subsequent differentiation in 3D extracellular matrix can be used as a robust in vitro assay for qualification and quantification of murine mammary stem/progenitor cells. This in vitro assay will greatly facilitate our understanding of genes regulate stem cell self-renewal, proliferation, differentiation as well as mechanisms keeping them at quiescent state within the niche.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-04-02.

Cytotoxic effects of MgO nanoparticles on human umbilical vein endothelial cells in vitro

The MgO nanoparticles are widely used in many fields. However, the toxicity of these nanoparticles to cells and organs remains fairly undiscovered. In this study, the cytotoxicity of MgO nanoparticles on human umbilical vein endothelial cells (HUVECs) in vitro was examined. The morphology and size of MgO nanoparticles were analysed by the transmission electron microscope (TEM) and nanoparticle size analyser. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2 h-tetrazolium bromide) assay, 4',6-diamidino-2-phenylindole (DAPI) staining analysis, NO release and total antioxidation competence (T-AOC) assay were used to evaluate the cytotoxicity of MgO nanoparticles. The results showed that most MgO nanoparticles were spherical with agglomerated state and the diameter of single particle was about 100 nm. Meanwhile, low concentration (below 200 [micro sign]g/ml) of MgO nanoparticles suspension showed no cytotoxicity by MTT assay. However, once the concentration of MgO nanoparticles was higher than 500 [micro sign]g/ml, the relative growth rate was lower than the control. The DAPI staining analysis results showed no significant difference of the cells morphology between the groups with or without MgO nanoparticles. In addition, the MgO nanoparticles significantly enhanced the NO release and T-AOC content of the HUVECs. The testing results indicated that low concentration of MgO nanoparticles exhibited non-cytotoxicity.

Extended-release niacin/laropiprant lipid-altering consistency across patient subgroups

BACKGROUND

In patients with primary hypercholesterolemia or mixed dyslipidemia, extended-release niacin/laropiprant (ERN/LRPT) improves key lipid parameters associated with increased atherosclerotic coronary heart disease (CHD) risk.

AIM

This analysis examined data from four Phase III, randomised, double-blind trials to determine the consistency of ERN/LRPT's lipid-altering efficacy among subgroups of patients.

METHODS

Data from four Phase III, randomised, double-blind trials of ERN/LRPT were analysed to determine the consistency of ERN/LRPT's lipid-altering efficacy among subgroups of gender, race (white, non-white), region (US, ex-US), baseline age (<65, ≥65 years), use of statin therapy, CHD risk status (low, multiple, high) and type of hyperlipidemia (primary hypercholesterolemia, mixed dyslipidemia), as well as across baseline low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglyceride (TG) levels. End-points included the per cent change from baseline in LDL-C, HDL-C and TG levels. Consistency of the treatment effects on LDL-C, HDL-C and TG across subgroups was evaluated by examining treatment difference estimates with 95% confidence intervals.

RESULTS

  Treatment with ERN/LRPT significantly improved LDL-C, HDL-C and TG levels compared with placebo/active comparator in each study cohort. These effects were generally consistent across all examined subgroups.

CONCLUSION

Extended-release niacin/laropiprant represents an effective therapeutic option for the treatment of dyslipidemia across a range of patient types.

Bisphosphonates induce senescence in normal human oral keratinocytes

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) commonly occurs in individuals receiving bisphosphonates (BPs) with clinical manifestations of the exposed necrotic bone. Although defective wound healing of soft tissue is frequently, if not always, observed in BRONJ, the effects of BPs on oral soft tissue or cells remain unknown. To investigate the effects of BPs on cells of oral mucosal tissue, we studied the effect of pamidronate (PAM), one of the BPs most commonly administered to cancer patients, on the phenotypes of normal human oral keratinocytes (NHOK) and fibroblasts (NHOF). When exposed to PAM at 10 µM, NHOK, not NHOF, underwent senescence: NHOK overexpressed senescence-associated β-galactosidase (SA-β-Gal), p16INK4A, IL-6, and IL-8. When exposed to a higher level (50 µM) of PAM, NHOK maintained senescent phenotypes, but NHOF underwent apoptosis. PAM-induced senescence in NHOK is mediated, in part, via geranylgeranylation of the mevalonate pathway. Our in vitro 3D oral mucosal tissue construction studies further demonstrated that PAM induced senescence and impaired re-epithelialization of oral mucosa. Analysis of these data indicates that premature senescence of oral mucosal cells and subsequent defective soft-tissue wound healing might be partly responsible for the development of BRONJ in individuals receiving PAM or other BPs.

Optimization of handling and refrigerated storage of guppy Poecilia reticulata sperm

Sperm collection methods and the effect of osmolality, ions, sugar, temperature, pH and dilution ratio on sperm motility were investigated in guppies Poecilia reticulata. The present study revealed that the sperm was motile in a wide range of osmolalities (200-470 mOsm kg(-1)) either in Hanks balanced-salt solution (HBSS) or in non-electrolyte solutions such as glucose or sucrose. Sperm collected from crushing testes yielded lower motility and shorter motility duration than samples collected without crushing but gentle disruption. Dilution ratios within the range of 1:50 to 1:500 of sperm to HBSS had minimal effect on sperm motility during extended refrigerated storage. Examination of storage temperature showed that refrigerated storage at 4 degrees C was superior to room temperature (25 degrees C). Sperm was found to tolerate a wide range of pH from 5.6 to 7.8, but motility was affected negatively by pH values >7.8.

Investigation of porcine endogenous retrovirus in the conservation population of Ningxiang pig

Porcine endogenous retrovirus (PERV) varies between pig breeds. Screening and analysis of PERV in putative pig breeds may provide basic parameters to evaluate the biological safety of xenotransplantation from pigs to humans. In this study, PERV was investigated among the conservation population of the Ningxiang pig. The result revealed that the genotype of PERV distribution was subtype A, 100%; subtype B, 100%; and subtype C, 100%. The env sequences of PERV-A and -B showed 11 clones detected by KpnI and MboI digestion, indicating that there existed multiple variants of PERV-A and -B in the Ningxiang pig. Reverse transcriptase polymerase chain reaction results showed that PERV had transcriptional activity in these individuals. In addition, PERV A/C recombinant was detected in most individuals of Ningxiang pig. Because PERV A/C recombinants increase the potential infectious risk, the breed may not be a proper donor for xenotransplantation.

Oxidative Stress and Apoptosis of Human Brain Microvascular Endothelial Cells Induced by Free Fatty Acids

Damage to endothelial cells is a key event in the pathogenesis of atherosclerosis and vascular disease. This study aimed to determine whether free fatty acids (FFAs) induced oxidative stress and apoptosis in human brain microvascular endothelial cells (HBMVECs) in vitro and, if so, which signalling pathway mediated these effects. After culture in different concentrations of FFAs for 24-72 h, cell viability/proliferation was determined using a cell counting kit, apoptosis was detected by measuring caspase-3 activity and by using annexin V-conjugated fluorescein isothiocyanate/propidium iodide staining, and oxidative stress was evaluated by measuring the levels of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP). The HBMVECs exposed to FFAs showed significantly decreased cell proliferation, increased apoptosis and ROS levels, and decreased MMP. In conclusion, the results showed that high levels of FFAs induced oxidative stress, which damaged HBMVECs and resulted in apoptosis.