[Factors Affecting the Labeling of NIH 3T3 Cells with Magnetic Nanoparticles].

The factors that affect the labeling of NIH 3T3 murine fibroblasts with Fe3O4-based magnetic nanoparticles (MNPs) were studied using MNPs produced by the gas condensation and solution precipitation methods and MNPs surface-modified with 3-aminopropylsilane or L-lysine. The production method, surface modifications, the particle concentration and size, the state of the cell population, and the method of MNP introduction were found to substantially affect the efficiency of MNP binding by cells. In particular, large MNP clusters may occur in MNP suspensions in DMSO, and their disruption by sonication increased the percent yield of magnetically labeled cells. Static incubation of a cell suspension led to a more efficient labeling as compared with continuous agitation. Cells attached to a plastic support could be labeled to a higher degree than cells in suspension, but required substantially longer incubations with MNPs. MNP centrifugation on cell layers (magnetic spinoculation) significantly increased the rate and efficiency of labeling. The stability of magnetic labeling was shown to depend on the MNP dose during labeling. Electron microscopy studies demonstrated that MNPs were associated with the cell surface after 20-min incubation with cells and were mostly in the cell interior after 4-h incubation. The results of the study may be useful for preparation and application of magnetized cell samples.

[Murine and human hematopoietic progenitor cultures grown on stromal layers expressing Notch ligands].

The ex vivo maintenance and expansion of hematopoietic stem cells and early progenitors is necessary for the successful treatment of hematopoietic and immune diseases. Multiple attempts to improve the expansion of hematopoietic stem cells (HSCs) by their cultivation in the presence of growth factor cocktails have so far failed. Novel approaches aimed at conserving the earliest precursors in their undifferentiated state are needed. These approaches should take into account local regulatory factors that are present in the HSC microenvironment and the three-dimensional architecture of their niche. In the present study, we compared the effects of two Notch ligands, i.e., Jagged1 and DLL1, on murine and human hematopoiesis in vitro. Our observations indicate that the stromal expression of Notch ligands increases the production of both the total and phenotypically early murine and human hematopoietic cells in the co-culture. On one hand, this study demonstrates the similarity of effects of stromal expression of Notch ligands on murine and human hematopoiesis in vitro. On the other hand, our study revealed a number of cell type and ligand-specific variations that are systematically described below. It seems that the effects of SCF cytokine addition on murine hematopoiesis in vitro depend on the stromal context and are oppositely directed for Jagged1 and DLL1.

[The synthesis of RGD peptide derivatives containing glutaric and adipic residues].

A method of the synthesis of RGD peptide derivatives containing glutaric or adipic residues linked with α-amino group of L-arginine and allowing carrying out their coupling with other biomolecules and nanoparticles.