Unlike humans, mouse bone marrow-derived mesenchymal stem cells (MSCs) cannot be easily harvested by adherence to plastic owing to the contamination of cultures by hematopoietic cells. The design of the protocol described here is based on the phenomenon that compact bones abound in MSCs and hematopoietic cells exist in the marrow cavities and the inner interfaces of the bones. The procedure includes flushing bone marrow out of the long bones, digesting the bone chips with collagenase type II, deprivation of the released cells and culturing the digested bone fragments, out of which fibroblast-like cells migrate and grow in the defined medium. The entire technique requires 5 d before the adherent cells are readily passaged. Further identification assays confirm that these cells are MSCs. We provide an easy and reproducible method to harvest mouse MSCs that does not require depletion of hematopoietic cells by sorting or immunomagnetic techniques.

Erythrocyte formation occurs throughout life in response to cytokine signaling. We show that microRNA-451 (miR-451) regulates erythropoiesis in vivo. Mice lacking miR-451 display a reduction in hematrocrit, an erythroid differentiation defect, and ineffective erythropoiesis in response to oxidative stress. 14-3-3ζ, an intracellular regulator of cytokine signaling that is repressed by miR-451, is up-regulated in miR-451−/− erythroblasts, and inhibition of 14-3-3ζ rescues their differentiation defect. These findings reveal an essential role of 14-3-3ζ as a mediator of the proerythroid differentiation actions of miR-451, and highlight the therapeutic potential of miR-451 inhibitors.

No abstract

First discovered in rural areas of middle-eastern China in 2009, severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne zoonosis affecting hundreds of cases reported in China each year. Using the national surveillance data from 2010 to 2013, we conducted this retrospective epidemiological study and risk assessment of SFTS in China. We found that the incidence of SFTS and its epidemic areas are continuing to grow, but the case fatality rate (CFR) has steadily decreased. SFTS most commonly affected elderly farmers who acquired infection between May and July in middle-eastern China. However, other epidemiological characteristics such as incidence, sex ratio, CFR, and seasonality differ substantially across the affected provinces, which seem to be consistent with local agricultural activities and the seasonal abundance of ticks. Spatial scan statistics detected three hot spots of SFTS that accounted for 69.1% of SFTS cases in China. There was a strong association of SFTS incidence with temporal changes in the climate within the clusters. Multivariate modeling identified climate conditions, elevation, forest coverage, cattle density, and the presence of Haemaphysalis longicornis ticks as independent risk factors in the distribution of SFTS, based on which a predicted risk map of the disease was derived.

The outbreak of human infections with an emerging avian influenza A (H7N9) virus occurred in China in early 2013. It remains unknown what and how the underlying risk factors were involved in the bird-to-human cross-species transmission. To illustrate the dynamics of viral spread, we created a thematic map displaying the distribution of affected counties and plotted epidemic curves for the three most affected provinces and the whole country. We then collected data of agro-ecological, environmental and meteorological factors at the county level, and used boosted regression tree (BRT) models to examine the relative contribution of each factor and map the probability of occurrence of human H7N9 infection. We found that live poultry markets, human population density, irrigated croplands, built-up land, relative humidity and temperature significantly contributed to the occurrence of human infection with H7N9 virus. The discriminatory ability of the model was up to 97.4%. A map showing the areas with high risk for human H7N9 infection was created based on the model. These findings could be used to inform targeted surveillance and control efforts in both human and animal populations to reduce the risk of future human infections.

New blood vessels are formed through the assembly or sprouting of endothelial cells (ECs) and become stabilized by the formation of perivascular matrix and the association with supporting mural cells. To investigate the role of endothelial Smad4 in vascular development, we deleted the Smad4 gene specifically in ECs using the Cre-LoxP system. EC-specific Smad4 mutant mice died at embryonic day 10.5 due to cardiovascular defects, including attenuated vessels sprouting and remodeling, collapsed dorsal aortas, enlarged hearts with reduced trabeculae, and failed endocardial cushion formation. Noticeably, Smad4-deficient ECs demonstrated an intrinsic defect in tube formation in vitro. Furthermore, the mutant vascular ECs dissociated away from the surrounding cells and suffered from impaired development of vascular smooth muscle cells. The disturbed vascular integrity and maturation was associated with aberrant expression of angiopoietins and a gap junction component, connexin43. Collectively, we have provided direct functional evidence that Smad4 activity in the developing ECs is essential for blood vessel remodeling, maturation, and integrity.

Resistance to platinum drugs has emerged as a major obstacle in the treatment of ovarian cancers. Through proteomic analysis, we have found that the expression of annexin A3, a member of the Ca 2+ and phospholipidbinding annexin family, is significantly increased in platinum-resistant ovarian cell lines. Anti-annexin A3 immunostaining indicated that cancers from platinum-resistant patients also possess higher levels of annexin A3 than those from platinum-sensitive patients. Although expression of annexin A3 made susceptible ovarian cancer cells more resistant to platinum, expression of antisense annexin A3 downregulated its expression and rendered the resistant cells more sensitive to platinum. In athymic mice, the growth of tumors from inoculated SKOV3 cells was inhibited by the administration of platinum, whereas tumors from annexin A3-expressing SKOV3/Ann were resistant to platinum treatment. Interestingly, the intracellular platinum concentration and platinum-DNA binding are significantly lower in annexin A3-overexpressing cells than those in parental cells. The lower cisplatin concentration was also accompanied by reduced induction of p53, which could be restored by downregulation of annexin A3. These results indicate that increased expression of annexin A3 is a mechanism of platinum resistance in ovarian cancer. It seems to act by preventing uptake or accumulation of platinum in cells. Therefore, it is conceivable that annexin A3 could be a target for therapeutic intervention and may also serve as a biomarker for drug resistance in ovarian cancer patients. Cancer Res; 70(4); 1616-24. ©2010 AACR.

Mesenchymal stem cells (MSCs IntroductionMesenchymal stem cells (MSCs) are defined as a group of multipotent stem cells that can functionally differentiate into at least bone, fat, and cartilage in vitro and in vivo. [1][2][3][4][5][6][7][8] Under appropriate culture conditions, MSCs are readily amplified in vitro for several passages without signs of senescence and differentiation. The 2 properties render them as an intriguing source in cell therapy and tissue engineering. MSCs were first documented by Friedenstein et al at an extremely low frequency within the bone marrow (BM), a canonical reservoir for a variety of stem cells. 1 Functionally, the self-renewal and differentiation of hematopoietic stem cells (HSCs) are tightly and precisely regulated by the marrow stromal milieu, a complex cellular network composed of the descendents of MSCs. For example, osteoblasts lining the bone surface can modulate the HSC expansion via Notch signaling pathway or N-cadherin/␤-catenin adherens complex in vitro and in vivo. 9,10 The MSC, itself, can also modulate hematopoiesis in vitro through secreting a set of hematopoietic cytokines and intercellular contact. 11,12 Systemic administration of adult or fetal tissue-derived MSCs promotes the homing and engraftment of HSCs in vivo by unknown mechanisms. [13][14][15][16] Despite of our increasing understanding of MSCs in adult hematopoiesis, little is known about their developmental origin and correlation with strikingly changing blood-forming sites during embryogenesis, particularly in the human being. 17 The first wave of hematopoiesis in humans is initiated during the third week in the extraembryonic yolk sac (YS), characterized by the production of nucleated erythrocytes in situ. 18,19 As is the case in other higher vertebrates, the second wave is characterized by de novo generation of HSCs in the intraembryonic P-Sp/AGM, followed by migration and colonizing downstream fetal liver for further maturation and amplification. [20][21][22][23] Campagnoli et al claim that human MSCs appear first in fetal blood at the seventh week, and later in the fetal liver and bone marrow from the 10th week. 24 Recently, Mendes et al reported that the mesenchymal progenitors are exclusively allocated in the mouse AGM. 25 However, the ontogeny of human MSCs in the embryonic hematopoietic tissues remains unknown.Herein, we found that human AGM region served as a potent niche for embryonic MSCs that were roughly identical to the bone marrow regarding general morphology, immunophenotype, triple differentiation capacity, and immunobiologic feature. The expression of pluripotential-related markers (Oct-4 and Nanog) and the hematopoietic supportive activity in AGM-derived MSCs corroborated their development stage and anatomic location. Methods Human samplesEighteen human embryos at 25 to 40 days of development were obtained immediately after voluntary terminations of pregnancy induced with the RU 486 antiprogestative compound. Human tissue collection for research purpose was approved by Research Eth...