[Non-carcinogenic health risk assessment of nickel in agricultural products and drinking water in an e-waste dismantling area of Qingyuan City, Guangdong Province].

Vegetables, rice, eggs and drinking water samples were collected from e-waste dismantling area of Qingyuan City, Guangdong Province. Nickel (Ni) was analyzed in each sample, and the non-carcinogenic health [the daily intake (DI) and hazard quotient (HQ)] of each sample was evaluated. In this e-waste dismantling area, the contents of Ni in rice and eggs were (0.46±0.24) and (0.16±0.13) µg/g, which were higher than those in the control area [the contents of Ni in rice and eggs were (0.17±0.03) and (0.02±0.02) µg/g, respectively] (both P values<0.05). The DI values of rice, vegetable, eggs, and drinking water were (3.61-5.86), (1.75-2.99), (0.11-0.24), and (0.08-0.12) µg·kg(-1)·day(-1), respectively. The HQ values were 0.180-0.290, 0.090-0.150, 0.005-0.010, 0.005-0.006, respectively. Although the HQ values of rice, vegetable, eggs, and drinking water were all lower than 1, which was an acceptable level. However, considering the possibility of combined exposure of heavy metals, the non-carcinogenic health risks of Ni in the e-waste dismantling area should still be concerned.

In vitro initial expansion of mesenchymal stem cells is influenced by the culture parameters used in the isolation process.

In the last years, there were many studies based on the use of human bone marrow mesenchymal stem cells (hMSCs) in cell therapy and tissue engineering. Although hMSCs can be easily obtained and expanded in culture, a large number of cells are often needed. The expansion of hMSCs depends on the culture conditions, such as media, cell density or culture flasks. Moreover, growth factors are often added to improve cell proliferation. In this study, we compared the effect of two culture media (DMEM and alpha-MEM), two culture flasks (75 or 25 cm2) and two different mononuclear cell seeding densities (1 x 10(4) or 5 x 10(4) MNC/cm2) on the isolation of hMSCs from bone marrow samples and analyzed if the isolation conditions affected the expansion of these cells in the first two passages. Experiments were performed without the addition of exogenous growth factors. Our results showed that alpha-MEM is the optimal culture medium for both, isolation and expansion of mesenchymal stem cells. Moreover, the cell seeding density of 50,000 MNC/cm2 in 25 cm2 culture flasks seems to be the best condition for the isolation step.