Sparse plating increases the heterogeneity of proliferative potential of fibroblasts

Mechanisms of Phototoxic Effects of Cationic Porphyrins on Human Cells In Vitro

The toxic effects of four cationic porphyrins on various human cells were studied in vitro. It was found that, under dark conditions, porphyrins are almost nontoxic, while, under the action of light, the toxic effect was observed starting from nanomolar concentrations. At a concentration of 100 nM, porphyrins caused inhibition of metabolism in the MTT test in normal and cancer cells. Furthermore, low concentrations of porphyrins inhibited colony formation. The toxic effect was nonlinear; with increasing concentrations of various porphyrins, up to about 1 μM, the effect reached a plateau. In addition to the MTT test, this was repeated in experiments examining cell permeability to trypan blue, as well as survival after 24 h. The first visible manifestation of the toxic action of porphyrins is blebbing and swelling of cells. Against the background of this process, permeability to porphyrins and trypan blue appears. Subsequently, most cells (even mitotic cells) freeze in this swollen state for a long time (24 and even 48 h), remaining attached. Cellular morphology is mostly preserved. Thus, it is clear that the cells undergo mainly necrotic death. The hypothesis proposed is that the concentration dependence of membrane damage indicates a limited number of porphyrin targets on the membrane. These targets may be any ion channels, which should be considered in photodynamic therapy.

Modification of human fibroblast properties in microtransplant

We studied the properties of human skin fibroblast in filamentous polyglycolic microtransplant. Fibroblast adhesion to the microtransplant filaments is followed by the formation of a network cross-linked with fibroblasts. The cells rapidly proliferate during the first few days; after transfer of the microtransplant to the standard culture flask, the cells migrate to the plastic and continue proliferation. The cells are uniform and exhibit high colony-formation capacity. The bundles of microtransplant filaments persist in the culture for several days and through the cells completely leave them, the area around these filaments remains the most populated for 40 days. Mitotic cells are seen in the immediate proximity to the degrading filaments of the transplant. The effect of cell "rejuvenation" in the microtransplant can be explained by selection of cells by their adhesion to relatively thin (about 15 μ) filaments, which excludes large old cells.

Isolation and culture of larval cells from C. elegans

Cell culture is an essential tool to study cell function. In C. elegans the ability to isolate and culture cells has been limited to embryonically derived cells. However, cells or blastomeres isolated from mixed stage embryos terminally differentiate within 24 hours of culture, thus precluding post-embryonic stage cell culture. We have developed an efficient and technically simple method for large-scale isolation and primary culture of larval-stage cells. We have optimized the treatment to maximize cell number and minimize cell death for each of the four larval stages. We obtained up to 7.8×10(4) cells per microliter of packed larvae, and up to 97% of adherent cells isolated by this method were viable for at least 16 hours. Cultured larval cells showed stage-specific increases in both cell size and multinuclearity and expressed lineage- and cell type-specific reporters. The majority (81%) of larval cells isolated by our method were muscle cells that exhibited stage-specific phenotypes. L1 muscle cells developed 1 to 2 wide cytoplasmic processes, while L4 muscle cells developed 4 to 14 processes of various thicknesses. L4 muscle cells developed bands of myosin heavy chain A thick filaments at the cell center and spontaneously contracted ex vivo. Neurons constituted less than 10% of the isolated cells and the majority of neurons developed one or more long, microtubule-rich protrusions that terminated in actin-rich growth cones. In addition to cells such as muscle and neuron that are high abundance in vivo, we were also able to isolate M-lineage cells that constitute less than 0.2% of cells in vivo. Our novel method of cell isolation extends C. elegans cell culture to larval developmental stages, and allows use of the wealth of cell culture tools, such as cell sorting, electrophysiology, co-culture, and high-resolution imaging of subcellular dynamics, in investigation of post-embryonic development and physiology.

Biogerontology in Russia: from past to future

The paper presents major steps of gerontology development in Russia. The issues of training in gerontology and geriatrics, institutional infrastructure within the Gerontological Society of the Russian Academy of Sciences and its activities have been considered therein. Some results of Russian researchers obtained during 2005-2010 have been summarized as well. Special attention is given to the prospects of gerontology in Russia.