Changes in negative surface charge of human diploid fibroblasts, TIG-1, during in vitro aging

Preparative enrichment of human tissue cells capable to change a site of growth in vitro or in vivo - Recent developments

Human cells are heterogeneous in regard to their biochemical features and functions. Detailed knowledge about each single cell type is important to understand the whole organism. In order to get a deeper insight in the concert of life, it has to be considered that cell populations such as thyroid cells, epithelial breast cells, endothelial cells, or chondrocytes are heterogeneous in regard to function, RNA expression patterns and protein content. This is true for normal cells and even more relevant for cancer cells. A number of sophisticated methods were developed to enrich cohorts of cells generally belonging to a defined type but outstanding by distinct characteristics, which can be detected by microscopic, proteomic or genomic methods. There is a great interest to investigate human cells, which are able to change their site of growth within the human body leaving an original site, migrating through vessels and reentering another site. In this review experiments are summarized showing that the application of microgravity-exposure of human cells and cell electrophoresis enable a characterization of cells, which leave a site of growth to enter another one. Biochemical features of separated subpopulations are described and their usefulness for deeper investigation is highlighted.

Mussel-Inspired Polymer Carpets: Direct Photografting of Polymer Brushes on Polydopamine Nanosheets for Controlled Cell Adhesion

2D mussel-inspired polydopamine (PDA) nanosheets are prepared and exploited as a functional surface for grafting various polymer brushes. The PDA nanosheet and its polymer-brush derivatives show lateral integrity and are robust; therefore, they can be detached from their substrates. Cell-adhesion tests show that the PDA nanosheet promotes cell growth and attachment, while a PDA-based poly(3-sulfopropyl methacrylate) carpet exhibits nonfouling behavior.

Locust bean gum as an alternative polymeric coating for embryonic stem cell culture

Pluripotent embryonic stem cells (ESCs) have self-renewal capacity and the potential to differentiate into any cellular type depending on specific cues (pluripotency) and, therefore, have become a vibrant research area in the biomedical field. ESCs are usually cultured in gelatin or on top of a monolayer of feeder cells such as mitotically inactivated mouse embryonic fibroblasts (MEFsi). The latter is the gold standard support to maintain the ESCs in the pluripotent state. Examples of versatile, non-animal derived and inexpensive materials that are able to support pluripotent ESCs are limited. Therefore, our aim was to find a biomaterial able to support ESC growth in a pluripotent state avoiding laborious and time consuming parallel culture of MEFsi and as simple to handle as gelatin. Many of the new biomaterials used to develop stem cell microenvironments are using natural polymers adsorbed or covalently attached to the surface to improve the biocompatibility of synthetic polymers. Locust beam gum (LBG) is a natural, edible polymer, which has a wide range of potential applications in different fields, such as food and pharmaceutical industry, due to its biocompatibility, adhesiveness and thickening properties. The present work brings a natural system based on the use of LBG as a coating for ESC culture. Undifferentiated mouse ESCs were cultured on commercially available LBG to evaluate its potential in maintaining pluripotent ESCs. In terms of morphology, ESC colonies in LBG presented the regular dome shape with bright borders, similar to the colonies obtained in co-cultures with MEFsi and characteristic of pluripotent ESC colonies. In short-term cultures, ESC proliferation in LBG coating was similar to ESC cultured in gelatin and the cells maintained their viability. The activity of alkaline phosphatase and Nanog, Sox2 and Oct4 expression of mouse ESCs cultured in LBG were comparable or in some cases higher than in ESCs cultured in gelatin. An in vitro differentiation assay revealed that mouse ESCs cultured in LBG preserve their tri-lineage differentiation capacity. In conclusion, our data indicate that LBG coating promotes mouse ESC growth in an undifferentiated state demonstrating to be a viable, non-animal derived alternative to gelatin to support pluripotent mouse ESCs in culture.

Extracellular matrix production and calcium carbonate precipitation by coral cells in vitro

The evolution of multicellularity in animals required the production of extracellular matrices that serve to spatially organize cells according to function. In corals, three matrices are involved in spatial organization: (i) an organic ECM, which facilitates cell-cell and cell-substrate adhesion; (ii) a skeletal organic matrix (SOM), which facilitates controlled deposition of a calcium carbonate skeleton; and (iii) the calcium carbonate skeleton itself, which provides the structural support for the 3D organization of coral colonies. In this report, we examine the production of these three matrices by using an in vitro culturing system for coral cells. In this system, which significantly facilitates studies of coral cell physiology, we demonstrate in vitro excretion of ECM by primary (nondividing) tissue cultures of both soft (Xenia elongata) and hard (Montipora digitata) corals. There are structural differences between the ECM produced by X. elongata cell cultures and that of M. digitata, and ascorbic acid, a critical cofactor for proline hydroxylation, significantly increased the production of collagen in the ECM of the latter species. We further demonstrate in vitro production of SOM and extracellular mineralized particles in cell cultures of M. digitata. Inductively coupled plasma mass spectrometry analysis of Sr/Ca ratios revealed the particles to be aragonite. De novo calcification was confirmed by following the incorporation of (45)Ca into acid labile macromolecules. Our results demonstrate the ability of isolated, differentiated coral cells to undergo fundamental processes required for multicellular organization.

Preferential reduction of the α-2-6-sialylation from cell surface N-glycans of human diploid fibroblastic cells by in vitro aging

Human diploid fibroblastic cell line, TIG-3, has a finite life span of about 80 population doubling levels (PDL), and is used for in vitro aging studies. Young cells (PDL 23) grew to higher cell densities at a higher growth rate than aged cells (PDL 77). When the electrophoretic mobility of cells was determined, the negative surface charge of the aged cells decreased significantly when compared to that of young cells. Lectin blot analysis of membrane glycoproteins showed that the alpha-2-6-sialylation but not the alpha-2-3-sialylation of N-glycans decreases markedly in the aged cells when compared to the young cells. In support of this observation, the cDNA microarray assay and reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that the gene expression of the alpha-2,6-sialyltransferase I (ST6Gal I), which transfers sialic acid to galactose residues of N-glycans, decreases in the aged cells. These results indicate that the concordant decrease of the alpha-2,6-sialylation of N-glycans with the ST6Gal I gene expression is induced in TIG-3 cells by in vitro aging.

Influence of Titanium Surface Charge on Fibroblast Adhesion

BACKGROUND

Although dental implants have a high success rate, failure owing to the absence of adhesion between the gingival connective tissue and the implant surface is still being reported.

PURPOSE

This study was designed to evaluate the effect of a titanium surface charge on fibroblast adhesion.

MATERIAL AND METHODS

An electrical chamber was custom-made to generate negative and positive surface charges on commercially pure titanium cylinders with a potential difference of 4.5 V. Twenty-seven titanium cylinders were divided into three experimental groups. In each group, cell attachment to a positively charged titanium cylinder, a negatively charged titanium cylinder, and a titanium cylinder (control) was studied at three time intervals of 15, 30, and 60 minutes. NCTC clone 929 fibroblasts were used in these experiments. The effect of the potential difference in the pH of Dulbecco's Modified Eagle Medium (DMEM) was also evaluated using two new specimens at time intervals of 15, 30, 60, and 80 minutes.

RESULTS

The fibroblast cell attachment was more statistically significant to the positively charged titanium cylinder than the negatively charged titanium cylinder (p =.002) and the control (p=.000), whereas the cell adhesion difference between the control and the negatively charged titanium cylinder was not statistically significant (p=.808). The range of pH difference of the DMEM in the negative and positive parts of the electrical chamber was 0.46 and 0.30, respectively.

CONCLUSION

Within the limitations of this in vitro study, the positive surface charge of the titanium cylinder results in significantly favorable cell adhesion.

Changes in biological characteristics during the cellular aging of ligament fibroblasts derived from patients with prolapsus uteri

Prolapsus uteri in pelvic support disorders are common in elderly women. The etiology is unclear and more likely to be multifactorial. We examined changes in biological characteristics and responsiveness to growth factors during the in vitro cellular aging of cardinal ligamental fibroblasts derived from patients with prolapsus uteri (HPLiF), and compared them with those of cells from age-matched control subjects (HCLiF). HPLiF and HCLiF had almost the same in vitro life span and the age-related patterns of biological parameters were essentially the same. However, the saturation density was significantly higher in HPLiF than in HCLiF. Furthermore, the high proliferative activity of HPLiF to serum mitogens, especially to platelet-derived growth factor, was retained throughout the in vitro life span. p53 protein levels in HPLiF increased at late passages, but were significantly less than in aged HCLiF. These results indicate that the higher proliferative activity in prolapsus fibroblasts may result from the decreased expression of p53 protein and may lead to a decrease in the synthesis and deposition of extracellular matrix components. These results support the hypothesis that functional alterations in ligament fibroblasts are involved in the mechanism of the development of prolapsus uteri.

Cellular electrophoretic mobility data: a first approach to a database

Cellular electrophoretic mobility values of 288 types of eucaryotic cells were collected from literature published worldwide by a series of authors during the past forty years and arranged in a list. This list contains well-known recent electrophoretic results and also data that cannot be found anymore with modern literature retrieval systems. It will be a valuable help for scientists trying to purify cell populations. In addition, it confirms the observation that most eucaryotic cells have very similar electrophoretic mobilities, ranging from 40% above to 50% below the electrophoretic mobility of human erythrocytes, and thus reinforces the suggestion that electrophoretic mobilities of eucaryotic cells are subjected to strong biological controls.

Age-related changes in collagen gel contraction by cultured human lung fibroblasts resulting in cross-over of contraction curves between young and aged cells

We examined the effects of population doubling levels on collagen gel contraction by human lung fibroblasts (TIG-1). The sizes of gels at day 4 of culture, when the number of cells was the same as the initial number, were smaller with young cells than with aged cells. Therefore, retractive force had decreased with in vitro cellular aging. On the other hand, the lag time until gel contraction began became shorter with aging, resulting in the cross-over of contraction curves of young and aged cells. Morphological changes, such as pseudopodia protrusion, were suppressed in collagen gel. The surrounding collagen fibrils prevented young cells from moving more than aged cells. The weakened omnidirectional interaction with collagen fibrils on the entire surface of aged cells might result in an earlier occurrence of morphological change and, thereby, gel contraction.

Changes in the cell surface of human diploid fibroblasts during cellular aging

The electrophoretic mobility of 13 human diploid cell strains, TIG-1, TIG-2, TIG-3, TIG-7, WI-38, IMR-90, MRC-5, MRC-9, TIG-1H, TIG-1L, TIG-2M, TIG-2B, and TIG-3S, which were established from different tissues of human embryos, was studied at different passages. The net negative surface charge of the cells was characteristic for each cell strain and decreased significantly during the in vitro aging of the cells. The decrease in the net negative charge of the cells correlated well with the decrease in cell density throughout the life span of the cells. A strict linear correlation between the electrophoretic mobility and the number of cells harvested at each passage was obtained for all the human diploid cell strains. Moreover, almost the same linear regression coefficient of the cells was obtained among these cell strains. Therefore, the net negative surface charge of human diploid cell strains could serve as a cell surface marker for in vitro cellular aging.

A new human male diploid cell strain, TIG-7: its age-related changes and comparison with a matched female TIG-1 cell strain

A new human diploid cell strain, TIG-7, which has the male karyotype, was established and characterized. Isozyme and histocompatibility typing of the cell strain was performed. The average in vitro life span of the cells is 73 population doublings. Changes in cell volume, doubling time, saturation density, the efficiency of cell attachment, plating efficiency, and relative DNA content were examined during in vitro cellular aging. Hydrocortisone slightly prolongs the life span of the cell strain when the hormone is administered to the cultures during middle passages. The age-related changes in the parameters of TIG-7 are not appreciably different from those of the previously established TIG-1 cell strain. These results show that this cell strain is useful for research on cellular aging; further profit is anticipated from research using a combination of these two sexually different cell strains.

Appearance of the terminal senescent cell population in human diploid fibroblasts analyzed by flow cytometry

We studied changes in the distribution pattern of relative RNA content during the in vitro aging of TIG-3 cells by flow cytometry (FACS III). Propidium iodide (PI) does not stain total cellular RNA, but it intercalates specifically into double-helical regions of both DNA and RNA. In applying this principle to RNA, we stained double-stranded RNA (dsRNA) in whole cells with PI after DNA digestion with DNase. The results showed that dsRNA distribution patterns were relatively constant at 7-75 population doublings (PD) but were significantly altered after 77 PD. The distribution patterns were similar as those for cell volume measured with a Coulter Counter. The total cellular dsRNA contents increased linearly at the senescent phase of their in vitro life span. In contrast, the mean dsRNA contents (50% dsRNA contents) rapidly increased to 77-79 PD, but decreased somewhat at 81-83 PD. Two-dimensional histograms of the dsRNA contents versus cell size were little altered from 25 PD to 75 PD. However, a population with relatively larger cell volume and weaker fluorescence intensity appeared and increased after 79 PD. This cell population group may be categorized as "terminal senescent cells" that no more divide in respect that the dsRNA content decreases in spite of the increase of total RNA content.