Effects of Nitrobenzenes on DNA Damage in Germ Cells of Rats

The single cell gel electrophoresis （SCGE） technique was used to detect DNA damage in germ cells of rats, which was induced by five tested nitroaromatic compounds. Mixed cultures of Sertoli and germ cells were prepared from the rats testis and their responses to rn-dinitrobenzene （ m-DNB）, 2,4-dinitrotoluene （ 2,4-DNT）, 2,6-dinitroto-luene（2,6-DNT）, 4-nitrotoluene（4-NT） and 2,4-dinitroaniline（2,4-DNAn） were studied. The results show that all the five chemicals have a reproductive toxicity. Each dose group and the control group were significantly different （ P 〈 0. 01 ）. All of them can lead to the damage to DNA in the germ cells of Kunming male rats in the definite range of concentration（m-DNB ： 0. 04-25μmol/L; 2,4-DNT, 2,6-DNT and 4-NT： 0. 032-500μmol/L; 2,4-DNAn ：0. 8-20μmol/L）. When the concentration increases, the damage rate will become higher, which shows an evident logarithm dose-effect relationship.

DNA damage of germ cell of rat induced by nitrotoluene chemicals

dinitrotoluene(2,4 DNT), 2,6 dinitrotoluene(2,6 DNT) and 4 nitrotoluene(4 NT) are typical pollutants in the Songhua River of Northeast China. Sertoli/germ cell cocultures and single cell gel electrophoresis(SCGE) are applied to investigate whether they have genotoxicity on DNA damage of germ cell of Kunming male rat. The results showed that all three nitrotoluene compounds tested could induce DNA single strand breaks of the germ cell. A significant relationship is found between logarithm dose and the degree of DNA damage, which implies that 2,4 DNT, 2,6 DNT and 4 NT have genotoxicity and can induce the germ cell DNA strand to break in vitro.

Osteoblast/fibroblast coculture derived bioactive ECM with unique matrisome profile facilitates bone regeneration

Extracellular matrix(ECM)with mimetic tissue niches was attractive to facilitate tissue regeneration in situ via recruitment of endogenous cells and stimulation of self-healing process.However,how to engineer the complicate tissue specific ECM with unique matrisome in vitro was a challenge of ECM-based biomaterials in tissue engineering and regenerative medicine.Here,we introduced coculture system to engineer bone mimetic ECM niche guided by cell-cell communication.In the cocultures,fibroblasts promoted osteogenic differentiation of osteoblasts via extracellular vesicles.The generated ECM(MN-ECM)displayed a unique appearance of morphology and biological components.The advantages of MN-ECM were demonstrated with promotion of multiple cellular behaviors(proliferation,adhesion and osteogenic mineralization)in vitro and bone regeneration in vivo.Moreover,proteomic analysis was used to clarify the molecular mechanism of MN-ECM,which revealed a specific matrisome signature.The present study provides a novel strategy to generate ECM with tissue mimetic niches via cell-cell communication in a coculture system,which forwards the development of tissue-bioactive ECM engineering along with deepening the understanding of ECM niches regulated by cells for bone tissue engineering.

Lanthanum chloride or citrate is absorbed mainly via M cells in gastrointestinal tracts with lanthanum phosphates as the transformed species

In the present study, we investigated the transformed species and the absorptive mechanism of rare earth elements（REEs） in gastrointestinal（GI） tract, using La Cl3 and La Cit as representative compounds. Artificial gastric and intestinal fluids were used to simulate the environment of the digestive tract in vivo. The inductively coupled plasma mass spectrometry（ICP-MS） result showed that more than 99.9% of La Cl3 and La Cit formed precipitation in artificial intestinal fluid, with the average size distribution of 200 nm（2-h incubation） increasing to 600 nm（24-h incubation） determined by dynamic light scattering（DLS）, indicating the aggregation of the particles. The Fourier transform infrared spectroscopy（FTIR） analysis demonstrated that the constituents of these particles were mainly in the form of lanthanum phosphates. To explore the transport mechanism of REEs in GI tract, the mice Peyer＇s patches（PPs） and intestinal epithelium were separated to evaluate the content of lanthanum by ICP-MS following oral administration with 2 or 100 mg/kg/day of La Cit for 7 d. The results showed that the amount of lanthanum phosphate particles absorbed by PPs was significantly greater than that of intestinal epithelium, indicating that lanthanum particles might be phagocytosed mainly by M cells located in the follicle-associated epithelium（FAE） overlying PPs. Furthermore, Caco-2 cell monoculture and Caco-2/Raji B cell coculture models were established to simulate intestinal epithelial cells and FAE, respectively. The result showed that the transport of lanthanum in Caco-2/Raji B coculture model was significantly higher than that in Caco-2 monoculture model（about 60 times higher）, and the level of lanthanum in the basal compartment of Caco-2 monoculture model was very low, supporting that M cells were the main route for lanthanum phosphate particles to be transported and absorbed. Taken together, these data suggested that La Cl3 and La Cit in GI tract were absorbed mainly via M cells with lanthanum phosphates as transformed species. The obtained results would provide the theoretical basis for the rational application of REEs in agriculture and medicine.