Zhu Zeng

Biophysical studies on the differentiation of human CD14+ monocytes into dendritic cells.

Dendritic cells (DCs), which are the most efficient antigen-presenting cells (APCs) currently known, can be derived from CD14+ monocytes (DC predecessor cells) in vitro. Immature DCs actively take up antigens and pathogens, generate major histocompatability complex-peptide complexes, and migrate from the sites of antigen acquisition to secondary lymphoid organs to become mature dendritic cells that interact with and stimulate T-lymphocytes. During this process, the cells must undergo deformation to translocate through several barriers, including the basement membrane and interstitial connective tissue in the blood vessel wall. To further understand the mechanisms of the activation of immunological responses and the migration from peripheral tissue to secondary lymphoid organs, we have applied biophysical and microrheological methods to study the development processes of DCs in vitro. The results showed that membrane fluidity, osmotic fragility, membrane viscoelastic properties, infrared spectroscopy, and cytoskeleton organization of DCs exhibit significant differences in different developmental stages.

Transforming growth factor-β1 deteriorates microrheological characteristics and motility of mature dendritic cells in concentration-dependent fashion

Dendritic cells (DCs) are potent and specialized antigen-presenting cells that play a crucial role in initiating and amplifying both the innate and adaptive immune responses. Tumor cells can escape from immune attack by secreting suppressive cytokines which solely or cooperatively impair the immune function and microrheological properties of DCs. However, the underlying mechanisms are not fully defined. Transforming growth factor-β1 (TGF-β1) has been identified as a major cytokine in the tumor microenvironment. To determine the effects of TGF-β1 on mature DCs (mDCs) from microrheological viewpoint, cells were treated with different concentrations of TGF-β1. The results showed that the impaired microrheological parameters, including osmotic fragility, electrophoretic mobility, deformability, membrane fluidity, F-actin organization and so on, as well as motilities of mDCs relied heavily on TGF-β1 concentration. Moreover, these changes were correlated with the expression levels of fascin1, cofilin1, phosphorylated cofilin1 and profilin, this could be one of the crucial aspects of immune escape mechanisms of tumors, hinting that the signal pathway of TGF-β1 should be blocked in appropriate way before performing DCs-based immunotherapy against cancer. It is clinically important to understand the biological behavior of DCs and immune escape mechanism of tumor as well as how to improve efficiency of the anti-tumor therapy based on DCs.

Exogenous Wild-Type p53 Gene Improved Survival of Nude Mice Injected with Murine Erythroleukemia Cell Line Through Amelioration of Hemorheological Changes

Objectives: Previous investigations have shown that human wild‐type p53 gene (WTp53) inhibits the growth of leukemia and tumor cells in vitro. In the present study, the authors used nude mice and examined the therapeutic role of p53 gene for erythroleukemia in vivo in the absence of MHC effects.

Effects of TFAR19 gene on the growth and biorheological properties of mouse erythroleukemia cell line MEL.

Using the method of gene transfection with liposome, we obtained the mouse erythroleukemia cell line MEL-TF19, which stably carries TFAR19, a novel apoptosis-related gene. The expression of TFAR19 was detected by Western blot. Growth curve and flow cytometry analysis showed that after being transfected with TFAR19 gene, the growth of MEL-TF19 is suppressed and its apoptosis is accelerated because of the serum deprivation. Our biorheological study indicated that in the apoptotic process, compared with MEL cells, MEL-TF19 cells exhibit larger osmotic fragility, lower cell surface charge density, increased elastic modulus K1 which is inversely proportional to cells’ maximal deformation ability, obviously diminished surface viscosity μ, with elastic modulus K2having no distinct changes. The above results provided some bases for recognizing the function of TFAR19 completely from the viewpoint of biorheology.

Biophysical and biorheological studies on the precursor cells at different stages

Splenic erythroblasts were obtained from mice during the acute disease caused by anemiainducing virus (FVA). They were cultured in a medium containing EPO, BSA and so on. We studied their biomechanical and hemorheological behavior after 12 h, 24 h and 48 h. The results showed obvious changes in their electrophoretic mobility, osmotic fragility, membrane fluidity and membrane viscoelastic properties with the development of erythroblast. The changes were associated with the interactions of the protein and lipid and the elements of the membrane.