BACKGROUND:Stem celltumorigenicity is a practical issue concerning stability in the clinical application of stem cells. Therefore, it is particularly important to clear whether stem cells have tumorigenic ability or not. Nude mice occupy an increasingly important position in oncology, immunology, and safety evaluation of drugs and biological products.
OBJECTIVE:To observe the tumorigenicity of neural stem cells and mesenchymal stem cells in Balb/c nude immunodeficient mice.
METHODS:Balb/c nude mice were randomly divided into control group, negative group, positive group, neural stem cellgroup and mesenchymal stem cellgroup. HepG-2 cells, RPE cells, passage 4 neural stem cells and mesenchymal stem cells were injected subcutaneously into nude mice from different groups, respectively. After 12 weeks of injection, anatomical observation was performed to detect the tumor formation in the transplantation site. Meanwhile, soft agar colony formation assay was applied to investigate neural stem celland mesenchymal stem cellclone in vitro.
RESULTS AND CONCLUSION:After 12 weeks of injection, the tumorigenicity study results showed that no tumor developed in the transplantation site in the control group, negative group, neural stem cellgroup and mesenchymal stem cellgroup. Histopathologic examinations also showed no abnormality in these groups. Soft agar colony formation assay showed in soft agar resistance medium, neural stem cells and mesenchymal stem cells did not exhibit clone ability. These findings indicate that neural stem cells and mesenchymal stem cells undergoing short-term passages have no tumorigenic growth.

BACKGROUND:Stem cells expansion technology in vitro is affected by the microenvironment of the culture system. So, to find an effective method is particularly important to promote celladherent and growth. OBJECTIVE:To compare the effects of different culture media on cellexpansion. METHODS:Human umbilical cord mesenchymal stem cells at a density of 5.0×104 cells/cm2 were inoculated into Corning? polystyrene culture dishes coated with or without poly-L-ornithine and Corning? cellBIND culture dishes. celladhesion and proliferation were observed, and expressions of celladhesion proteins and cellmarkers were detected. RESULTS AND CONCLUSION:celladhesion was promoted when cells were cultured in Corning? cellBIND? Surface medium coated with poly-L-ornithine for 24 hours, and the cultured cells grew at the logarithmic phase. The cellproliferation was also enhanced, and the cells expressed celladhesion protein but not the cellmarkers of CD73, CD90, CD105. Corning? cellBIND? Surface medium was superior to Corning? polystyrene culture medium in the improvement of celladhesion and proliferation. Additional y, both of these two media showed no influence on cellphenotype. These findings indicate that Corning? cellBIND? Surface medium can promote celladhesion and proliferation, but shows no effects on cyclin and cellphenotype. This medium coated with poly-L-ornithine can further accelerate celladhesion and proliferation, and stably express cellphenotype of human umbilical cord mesenchymal stem cells.

Bifendate, a synthetic anti-hepatitis drug, exhibits polycrystalline mode phenomena with 2 polymorphs reported (forms A and B). Single crystals of the known crystalline form B and 3 new crystallosolvates involving bifendate solvated with tetrahydrofuran (C), dioxane (D), and pyridine (E) in a stoichiometric ratio of 1:1 were obtained and characterized by X-ray crystallography, thermal analysis, and Fourier transform infrared (FT-IR) spectroscopy. The differences in molecular conformation, intermolecular interaction and crystal packing arrangement for the four polymorphs were determined and the basis for the polymorphisms was investigated. The rotation of single bonds resulted in different orientations for the biphenyl, methyl ester and methoxyl groups. All guest solvent molecules interacted with the host molecule via an interesting intercalative mode along the [1 0 0] direction in the channel formed by the host molecules through weak aromatic stacking interactions or non-classical hydrogen bonds, of which the volume and planarity played an important role in the intercalation of the host with the guest. The incorporation of solvent-augmented rotation of the C-C bond of the biphenyl group had a striking effect on the host molecular conformation and contributed to the formation of bifendate polymorphs. Moreover, the simulated powder X-ray diffraction (PXRD) patterns for each form were calculated on the basis of the single-crystal data and proved to be unique. The single-crystal structures of the four crystalline forms are reported in this paper.