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Biomedical subjects

J-F Stoltz

Publications and source records attributed to J-F Stoltz.

9 recordsLinked to original sources
PubMed2006

Initial adhesion of endothelial cells on polyelectrolyte multilayer films.

Polyelectrolyte multilayer films were recently investigated to favour attachment of Human Vein Umbilical Endothelial Cells (HUVECs) on non-adhesive surfaces. In this study, we evaluated the initial adhesion of HUVECs after 3 h of seeding on two polyelectrolyte multilayer films ending by poly(D-lysine) (PDL) or poly(allylamine hydrochloride) (PAH). In order to obtain information about initial adhesion of HUVECs, cell morphology as well as the expression of beta1 integrins, specific receptors of adhesion, were evaluated after 3 h of seeding on polyelectrolyte multilayer films. The data were also compared to PDL or PAH monolayers (polyelectrolytes terminating the multilayer architecture). The expression of beta1 integrins was not different, whatever are the studied surfaces. However, HUVECs spreading on polyelectrolyte multilayer films, in particular on PAH ending film, was more important as compared to polyelectrolyte monolayers or glass. In conclusion, the best initial adhesion conditions of HUVECs on polyelectrolyte films could not be elucidated, moreover the results suggested also that beta1 integrins could only play a limited role.

Actins↗
PubMed2006

Decellularized umbilical artery treated with thin polyelectrolyte multilayer films: potential use in vascular engineering.

Decellularized allograft tissues have been identified as a potential extracellular matrix scaffold for tissue-engineered vascular substitutes. In order to improve the thromboresistance, it is necessary to pre-coat the intra-luminal vessel surface. Recently a new surface modification technique appeared, based on the alternate adsorption of positive and negative charged polyelectrolytes. Our objective was to develop an alternative vascular scaffold made of decellularized human umbilical arteries treated with a PAH/PSS polyelectrolyte multilayered film. The vessels luminal surfaces covered with the multilayer film were observed by electronic scanning microscopy. Our observations showed that the luminal surface is completely devoid of ECs following treatment with trypsin. A top view of the coated artery indicated that the multilayer uniformly covered internal surface of the vessels. The successful of the multilayer correct deposition and retention on the arterial wall were controlled by confocal microscopy using a fluorescent polyelectrolyte (rhodamine-PAH). The data suggest that decellularized cryopreserved arteries represent a potential scaffold for further vascular tissue engineering efforts. Moreover, the multilayer films can be used to coat biological surfaces and following the terminated layer (PAH or PSS), favour the cell adhesion or cell resistance.

Arteries↗
PubMed2005

Kinetics of the endocytotic pathway of Low Density Lipoprotein (LDL) in human endothelial cells line under shear stress: an in vitro confocal microscopy study.

We studied the effect of mechanical forces (shear stress) on the kinetics of internalization of native LDL and ox-LDL in endothelial cell line ECV304. This study was performed by using Confocal microscopy and FRET with two carbocyanine dyes, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiO) as the donor and 3,3'-dioctadecyloxacarbocyanine perchlorate (DiI) as the receptor. The cells were incubated with a culture medium containing either 10 microg/ml DiI-LDL or DiO-LDL in static conditions or subjected to a laminar flow under a Confocal Laser Scanning Microscope (SP2 Leica, Germany). The results showed: (1) the possibility to evaluate the kinetics of LDL endocytosis in living cells, (2) shear stress in comparison with control group more effectively enhanced LDL uptake, (3) ox-LDL (>50 microg/ml) >4 hours incubation was found to affect the cells as reflected by their detachment at low shear stress.

Cell Line↗
PubMed2005

New tool to monitor membrane potential by FRET Voltage Sensitive Dye (FRET-VSD) using Spectral and Fluorescence Lifetime Imaging Microscopy (FLIM). Interest in cell engineering.

In this work, we investigated a voltage-sensitive fluorescent system to monitor membrane potential by spectral and lifetime fluorescence microscopy. A two-component FRET sensor has been designed that utilizes fluorescent phospholipids acceptor (DHPE-TRITC) bound on one side of the membrane and donor molecules (oxonol) which are sensitive to membrane potential. We used multiphoton excitation and FLIM to deliver contrast lifetimes of different line cancerous cells. These results provide new information concerning the differential response to depolarized cancerous cells from resting cells when compared to fibroblast normal cells. Given the sensitivity and the fast time response, this FRET system may be particularly useful for applications involving compression of tissues by mechanical forces.

Animals↗
PubMed2004

From hemorheology to vascular mechanobiology: An overview.

Almost all of the cells of the human body are subjected to mechanical stresses. In endothelial cells, mechanical stresses can vary from some milli-Pascal (shear stress) to one ore more Pascal (hydrostatic pressure). Now it is know that mechanical stresses have a decisive part cellular physiology. However, if the main biological effects of mechanical stress are well related, the mechanisms allowed the relation between mechanical stress to physiological phenomenon remain nearly unknown (mechanotransduction phenomenon). In this work, through personal results and published works, the authors considers all the effects of mechanical stresses and the possible hypothesis.

Blood Vessels↗
PubMed2003

Modeling of the detachment of a molecule from a surface: illustration of the "Bell-Evans effect".

This article deals with the modeling of the detachment of a molecule initially adsorbed on a surface and submitted to an external force whose strength increases with time. By means of an atomic force microscope (AFM), it is possible to measure the force when the molecule separates from the substrate. However, it is known that this force depends to a large extend on the rate at which the pulling force is applied ("Bell-Evans effect"). Two models are described to illustrate this behavior. First, a random walk approach is suggested to reveal the fundamental principle of the escape over a time-dependent energy barrier. Second, a multi bead-and-spring model is proposed to mimic the AFM experiment and numerical simulations, based on Brownian dynamics, are performed.

Binding Sites↗
PubMed2002

From biomechanics to mechanobiology.

Biomechanics can be defined as the application of mechanical concepts to the living world, and various fields of research have been developed such as the mechanics of movement, ergonomics, the mechanical properties of cells and tissues, and the relationship between physiology and applied forces. In this paper, the authors give, through several examples, an outline of these approaches and their potential biomedical applications, as in tissue remodelling, cell and tissue engineering and the development of biotissues.

Biomechanical Phenomena↗
PubMedDate not supplied

Cell interactions with polyelectrolyte multilayer films.

The short-term interactions of chondrosarcoma cells with polyelectrolyte multilayer films built up by the alternate adsorption of poly(L-lysine) (PLL) and poly(L-glutamic acid) (PGA) was studied in the presence and in the absence of serum. The films and their interaction with serum proteins were first characterized by means of optical waveguide lightmode spectroscopy, quartz crystal microbalance, and zeta potential measurements. In a serum-containing medium, the detachment forces measured by the micropipet technique were about eight times smaller on PGA-ending than on PLL-ending films. For these latter ones, the adhesion force decreased when the film thickness increased. In a serum-free medium, the differences between the negative- and positive-ending films were enhanced: adhesion forces on PLL-ending films were 40-100% higher, whereas no cellular adherence was found on PGA-terminating films. PGA-ending films were found to prevent the adsorption of serum proteins, whereas important protein adsorption was always observed on PLL-ending films. These results show how cell interactions with polyelectrolyte films can be tuned by the type of the outermost layer, the presence of proteins, and the number of layers in the film.

Blood Proteins↗