One Health operations: a critical component in the International Health Regulations Monitoring and Evaluation Framework.

Under the International Health Regulations (IHR, 2005), a legally binding document adopted by 196 States Parties, countries are required to develop their capacity to rapidly detect, assess, notify and respond to unusual health events of potential international concern. To support countries in monitoring and enhancing their capacities and complying with the IHR (2005), the World Health Organization (WHO) developed the IHR Monitoring and Evaluation Framework (IHR MEF). This framework comprises four complementary components: the State Party Annual Report, the Joint External Evaluation, after-action reviews and simulation exercises. The first two are used to review capacities and the second two to help to explore their functionality. The contribution of different disciplines, sectors, and areas of work, joining forces through a One Health approach, is essential for the implementation of the IHR (2005). Therefore, WHO, in partnership with the Food and Agriculture Organization of the United Nations (FAO), the World Organisation for Animal Health (OIE), and other international and national partners, has actively worked on facilitating the inclusion of the relevant sectors, in particular the animal health sector, in each of the four components of the IHR MEF. Other tools complement the IHR MEF, such as the WHO/OIE IHR-PVS [Performance of Veterinary Services] National Bridging Workshops, which facilitate the optimal use of the results of the IHR MEF and the OIE Performance of Veterinary Services Pathway and create an opportunity for stakeholders from animal health and human health services to work on the coordination of their efforts. The results of these various tools are used in countries' planning processes and are incorporated in their National Action Plan for Health Security to accelerate the implementation of IHR core capacities. The present article describes how One Health is incorporated in all components of the IHR MEF.

En vertu du Règlement sanitaire international (RSI, 2005), instrument juridique ayant force obligatoire pour les 196 États Parties dans le monde, les pays s'engagent à renforcer leurs capacités de détection, d'évaluation, de notification et de réaction en cas d'événements sanitaires inhabituels ou présentant une dimension internationale inquiétante. Le Cadre de suivi et d'évaluation du RSI (2005) a été élaboré par l'Organisation mondiale de la santé (OMS) afin de soutenir les pays souhaitant évaluer et améliorer leurs capacités et leur niveau de conformité avec le RSI (2005). Ce cadre comprend quatre composantes complémentaires : le rapport annuel de l'État Partie, l'Évaluation extérieure conjointe, les examens « après action¼ et les exercices de simulation. Les deux premières composantes permettent de faire le point sur les capacités tandis que les deux dernières visent une connaissance détaillée de leur fonctionnement. La mise en oeuvre du RSI (2005) demande aux différentes disciplines, secteurs et domaines d'activités de fédérer leurs forces dans une approche Une seule santé. Par conséquent, en partenariat avec l'Organisation des Nations Unies pour l'alimentation et l'agriculture (FAO), avec l'Organisation mondiale de la santé animale (OIE) et avec d'autres partenaires internationaux et nationaux, l'OMS a fait en sorte de faciliter l'intégration de tous les secteurs concernés, en particulier celui de la santé animale, dans les diverses composantes du Cadre d'évaluation du RSI. D'autres outils complètent celui-ci, en particulier les ateliers de liaison nationaux OMS/OIE sur le RSI et le Processus d'évaluation des performances des Services vétérinaires (PVS), dont le but est de faciliter l'utilisation optimale des résultats du Cadre d'évaluation du RSI et du Processus PVS de l'OIE et de fournir aux acteurs des services de santé animale et de santé publique la possibilité de se concerter sur les modalités d'une synergie de leur action. Les résultats de ces outils sont ensuite pris en compte par les pays lors des procédures de planification et intégrés dans les Plans d'action nationaux pour la sécurité sanitaire afin d'accélérer la mise en oeuvre des capacités fondamentales décrites dans le RSI. Les auteurs décrivent l'intégration du concept Une seule santé dans chacune des composantes du Cadre d'évaluation du RSI.

Según lo dispuesto en el Reglamento Sanitario Internacional (RSI, 2005), documento jurídicamente vinculante suscrito por 196 Estados Partes, los países están obligados a dotarse de la capacidad necesaria para detectar, evaluar, notificar y afrontar con rapidez todo evento sanitario inusual que pueda revestir importancia internacional. Para ayudar a los países a dotarse de mejores capacidades, a seguir de cerca su evolución al respecto y a dar cumplimiento al RSI (2005), la Organización Mundial de la Salud (OMS) elaboró el marco de seguimiento y evaluación del RSI, que consta de cuatro elementos complementarios: el informe anual que debe presentar cada Estado Parte; la evaluación externa conjunta; exámenes posteriores a las intervenciones; y ejercicios de simulación. Los dos primeros sirven para examinar las capacidades, y los dos segundos para ayudar a estudiar su funcionalidad. Para la aplicación del RSI (2005) es fundamental la contribución de diferentes disciplinas, sectores y ámbitos de trabajo, que aúnen esfuerzos actuando desde los postulados de Una sola salud. Por ello la OMS, en colaboración con la Organización de las Naciones Unidas para la Alimentación y la Agricultura (FAO), la Organización Mundial de Sanidad Animal (OIE) y otros asociados internacionales y nacionales, ha trabajado activamente para facilitar la integración de los sectores pertinentes, en particular el de la sanidad animal, en cada uno de los cuatro componentes del marco de seguimiento y evaluación del RSI. Hay otros dispositivos que vienen a complementar este marco, por ejemplo los talleres nacionales dedicados a la creación de nexos entre el RSI y el proceso PVS (Prestaciones de los Servicios Veterinarios) de la OIE, organizados conjuntamente por la OMS y la OIE, que facilitan un uso idóneo de los resultados del marco de seguimiento y evaluación del RSI y del proceso PVS y brindan a las partes interesadas de los servicios sanitarios y zoosanitarios la oportunidad de trabajar sobre la coordinación de sus respectivas actividades. Los resultados de estas diversas herramientas alimentan después los procesos de planificación de los países y son incorporados a su Plan de acción nacional de seguridad sanitaria para acelerar la implantación de las capacidades básicas prescritas en el RSI. Los autores explican cómo se incorpora la filosofía de Una sola salud a todos los componentes del marco de seguimiento y evaluación del RSI.

Establishment of public health security in Saudi Arabia for the 2009 Hajj in response to pandemic influenza A H1N1.

Mass gatherings of people challenge public health capacities at host locations and the visitors' places of origin. Hajj--the yearly pilgrimage by Muslims to Saudi Arabia--is one of the largest, most culturally and geographically diverse mass gatherings in the world. With the 2009 pandemic influenza A H1N1 and upcoming Hajj, the Saudi Arabian Ministry of Health (MoH) convened a preparedness consultation in June, 2009. Consultants from global public health agencies met in their official capacities with their Saudi Arabian counterparts. The MoH aimed to pool and share public health knowledge about mass gatherings, and review the country's preparedness plans, focusing on the prevention and control of pandemic influenza. This process resulted in several practical recommendations, many to be put into practice before the start of Hajj and the rest during Hajj. These preparedness plans should ensure the optimum provision of health services for pilgrims to Saudi Arabia, and minimum disease transmission on their return home. Review of the implementation of these recommendations and their effect will not only inform future mass gatherings in Saudi Arabia, but will also strengthen preparedness efforts in other settings.

In vitro inhibition of IL-1beta catabolic effects on cartilage: a mechanism involved on diacerein anti-OA properties.

Osteoarthritis (OA) is a progressive joint disease which represents a combination of several disorders leading to cartilage degradation. The main characteristic of OA is an imbalance between chondrocyte anabolic and catabolic activities. Cytokines produced by the synovium and chondrocytes, especially interleukin 1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha), play a significant role in the degradation of cartilage. They stimulate the production of nitric oxide (NO), which is involved in cartilage catabolism and also may induce the apoptosis of chondrocytes. The IL-1beta produced in activated chondrocytes or synovium may modulate disease progression in OA and should therefore be considered a potential target for therapeutic interventions. Drug and non-drug treatments are used to relieve pain and/or swelling in OA. Diacerein is a slow-acting drug that may slow down the breakdown of cartilage and relieve pain and swelling. It is not clear whether diacerein works but it has been proposed that diacerein acts as a symptom-modifying and perhaps disease-structure modifying drug.

Interest of second harmonic generation imaging for diagnosis in thick and opaque tissue.

In articular hyaline cartilage, chondrocytes are surrounded by an extracellular matrix which is mainly composed by collagen and proteoglycanes. Pathological specimens show a partial or complete degradation of this matrix. Therefore, it could be interesting to know how mechanical or biochemical constraints applied to cartilage specimens induce modifications of the cartilage network. Multiphoton technology combined to Second Harmonic Generation (SHG) enables to image cartilage specimens in a non-invasive mode with high resolution at deep penetration. By placing a band pass filter in front of the transmitted light detector, SHG signal with frequency doubled can be isolated for a new contrast imaging. SHG (second harmonic generation) is a diffusion process generated from organized structures and does not need any fluorescent staining. Due to their non-centrosymetric structure, collagen fibrilles present a high second-order non-linear susceptibility and thus give rise to a strong SHG signal when exposed to high enough electric fields produced by a focal point of a femtosecond pulsed laser (multiphoton microscopy). As the extracellular matrix of cartilage is in part constituted by collagen fibers, it can be imaged with this contrast tool. The intensity of SHG signals strongly depends on the organization of collagen fibers. Thus a modification of the extracellular matrix in terms of 3D-organization of collagen induced by mechanical stress can be shown with this contrast tool.

Influences of construct properties on the proliferation and matrix synthesis of dedifferentiated chondrocytes cultured in alginate gel.

To investigate whether the chondrocytes-alginate construct properties, such as cell seeding density and alginate concentration might affect the redifferentiation, dedifferentiated rat articular chondrocytes were encapsulated at low density (LD: 3 x 10(6) cells/ml) or high density (HD: 10 x 10(6) cells/ml) in two different concentrations of alginate gel (1.2% or 2%, w/v) to induce redifferentiation. Cell viability and cell proliferation of LD culture was higher than those of HD culture. The increase in alginate gel concentration did not make an obvious difference in cell viability, but reduced cell proliferation rate accompanied with the decrease of cell population in S phase and G2/M phase. Scan electron microscopy observation revealed that chondrocytes maintained round in shape and several direct cell-cell contacts were noted in HD culture. In addition, more extracellular matrix was observed in the pericellular region of chondrocytes in 2% alginate culture than those in 1.2% alginate culture. The same tendency was found for the synthesis of collagen type II. No noticeable expression of collagen type I was detected in all constructs at the end of 28-day cultures. These results suggested that construct properties play an important role in the process of chondrocytes' redifferentiation and should be considered for creating of an appropriate engineered articular cartilage.

Polyelectrolyte multilayer films: effect of the initial anchoring layer on the cell growth.

In tissue engineering, surface characteristics of a biomaterial are one of most important factors determining the compatibility with the environment. They influence attachment and growth of cells onto the material. In many cases, the surface should to be modified and engineered in the desired direction. The modification of non-adhesive surfaces with polyelectrolyte multilayer films (PMF) was recently depicted as a powerful technique to promote the growth of different cell lines. In this study, we evaluated the possible use of two different PMF as surface modification for the culture of mesenchymal stem cells (MSC). We used two types of PMF which differed by the nature of the initial anchoring layer which was poly(ethylenimine) (PEI) or poly(allylamine hydrochloride) (PAH). This initial polyelectrolytes adsorption was followed by the alternated deposition of poly(sodium 4-styrenesulfonate) (PSS) and (PAH) in order to obtain a PEI-(PSS-PAH)(3) film or a PAH-(PSS-PAH)(3) film. In order to control the behaviour of MSC, the cell viability was evaluated by Alamar Blue assay and the actin cytoskeleton was labelled and visualised in a confocal microscope. The behaviour of cells on the two PMF was compared to cells cultivated on surfaces treated with fibronectin. The results showed that PAH-(PSS-PAH)(3) PMF improve the growth of cells, inducing a higher cell viability compared to PEI-(PSS-PAH)(3) PMF and fibronectin at 2, 3 and 7 days of culture. Moreover, those cells showed a well-organized actin cytoskeleton. In conclusion, PAH-(PSS-PAH)(3) polyelectrolyte multilayer film seems to constitute an excellent material for MSC seeding.

In vitro effects of diacerein on NO production by chondrocytes in response to proinflammatory mediators.

Osteoarthritis (OA) is a progressive joint disease which represents a combination of several disorders leading to cartilage degradation. The production of nitric oxide (NO) by iNOS, which is stimulated by proinflammatory mediators, is involved in cartilage catabolism and should therefore be considered a potential target for therapeutic interventions. Diacerein is a slow-acting drug that may slow down the breakdown of cartilage and relieve pain and swelling. Diacerhein, in contrast to an NSAID, is a potent inhibitor of IL-1beta induced NO production by chondrocytes and cartilage. This effect appeared to result from iNOS transcriptional and/or post-transcriptional events, maybe by the inhibition of the NF-kappaB transcription factor. This paper presents results on the influence of Diacerein on NO production.

Potential relation between cytoskeleton reorganization and e-NOS activity in sheared endothelial cells (Effect of rate and time of exposure).

Endothelial cells (ECs) which participate the interface between the blood and the vessel wall undergo morphologic changes in response to shear stress induced by blood flow, liable for the important regulation on physiologic and pathophysiologic function of blood vessels. Shear stress induced changes in cell morphology, begin with elongation in the direction of shearing and end by a reorientation and assembly of F-actin stress fibers. Shear stress is also implicated in many important ECs functions such as: decrease of platelet aggregation, anti-thrombogenic and anti-adhesive effects, inhibition of vascular smooth muscle cell (SMC) proliferation and regulation of their contraction and arterial tonicity, via a regulation of vasodilator and vasoconstrictor secretion molecules such as nitric oxide (NO), endothelin I, prostacyclin and angiotensin II. Besides, many of human diseases such as hypercholesterolemia, diabetes and hypertension, are strongly linked to a disturbance of the production of several vasodilator or vasoconstrictor molecules. The aim of this in-vitro study was to evaluate the potential balance between time and rate effects of shearing in cell shape changes and e-NOS activity. Two unidirectional steady laminar flow rates (1.2 Pa and 2.0 Pa) were applied on EC monolayers, each one for a short and a long period, (6 h and 24 h). Cytoskeleton reorganization was evaluated by actin filaments labelling and observed by confocal microscopy. NO production was evaluated by a colorimetric method using the Griess reagent kit for nitrite determination. Results showed that laminar flow affected cell rearrangement by inducing cytoskeleton reorientation and increased production of NO. Laminar shear rate at 2.0 Pa for 24 h did not upregulate NO release. Whereas at 1.2 Pa for 24 h, NO release increased by 33% compared with the static conditions. Both 1.2 Pa and 2.0 Pa for 6 h increased NO release by 17% and 24% respectively as compared with the static conditions. These observations suggested that stress fiber assembly, which controls EC reorientation and NO production, are dependent on rate and time of shearing. In addition, there appear to be a relation between the cytoskeleton reorganization stage and NO production. These results could promote the parameters to evaluate the more appropriate pattern of shearing, to evaluate a potential pharmacological effect on hypertension disorder decrease.

Organ reconstruction: Dream or reality for the future.

The relevance of research on reconstructed organs is justified by the lack of organs available for transplant and the growing needs for the ageing population. The development of a reconstructed organ involves two parallel complementary steps: de-cellularization of the organ with the need to maintain the structural integrity of the extracellular matrix and vascular network and re-cellularization of the scaffold with stem cells or resident cells.Whole organ engineering for liver, heart, lung or kidneys, is particularly difficult because of the structural complexity of organs and heterogeneity of cells. Rodent, porcine and rhesus monkey organs have been de-cellularized to obtain a scaffold with preserved extracellular matrix and vascular network. As concern the cells for re-cellularization, embryonic, foetal, adult, progenitor stem cells and also iPS have been proposed.Heart construction could be an alternative option for the treatment of cardiac insufficiency. It is based on the use of an extra-cellular matrix coming from an animal's heart and seeded with cells likely to reconstruct a normal cardiac function. Though de-cellularization techniques now seem controlled, the issues posed by the selection of cells capable of generating the various components of cardiac tissue are not settled yet. In addition, the recolonisation of the matrix does not only depend on the phenotype of cells that are used, but it is also impacted by the nature of biochemical signals emitted.Recent researches have shown that it is possible to use decellularized whole liver treated by detergents as scaffold, which keeps the entire network of blood vessels and the integrated extracellular matrix (ECM). Beside of decellularized whole organ scaffold seeding cells selected to repopulate a decellularized liver scaffold are critical for the function of the bioengineered liver. At present, potential cell sources are hepatocyte, and mesenchymal stem cells.Pulmonary regeneration using engineering approaches is complex. In fact, several types of local progenitor cells that contribute to cell repair have been described at different levels of the respiratory tract. Moving towards the alveoles, one finds bronchioalveolar stem cells as well as epithelial cells and pneumocytes. A promising option to increase the donor organ pool is to use allogeneic or xenogeneic decellularized lungs as a scaffold to engineer functional lung tissue ex vivo.The kidney is certainly one of the most difficult organs to reconstruct due to its complex nature and the heterogeneous nature of the cells. There is relatively little research on auto-construction, and experiments have been performed on rats, pigs and monkeys.Nevertheless, before these therapeutic approaches can be applied in clinical practice, many researches are necessary to understand and in particular the behaviour of cells on the decellularized organs as well as the mechanisms of their interaction with the microenvironment. Current knowledges allow optimism for the future but definitive answers can only be given after long term animal studies and controlled clinical studies.

Mechanobiology of mesenchymal stem cells: Which interest for cell-based treatment?

Thanks to their immune properties, the mesenchymal stem cells (MSC) are a promising source for cell therapy. Current clinical trials show that MSC administrated to patients can treat different diseases (graft-versus-host disease (GVHD), liver cirrhosis, systemic lupus, erythematosus, rheumatoid arthritis, type I diabetes…). In this case, the most common mode of cell administration is the intravenous injection, and the hemodynamic environment of cells induced by blood circulation could interfere on their behavior during the migration and homing towards the injured site. After a brief review of the mechanobiology concept, this paper will help in understanding how the mechanical environment could interact with MSC behavior once they are injected to patient in cell-based treatment.

Aging of bone marrow mesenchymal stromal/stem cells: Implications on autologous regenerative medicine.

With their proliferation, differentiation into specific cell types, and secretion properties, mesenchymal stromal/stem cells (MSC) are very interesting tools to be used in regenerative medicine. Bone marrow (BM) was the first MSC source characterized. In the frame of autologous MSC therapy, it is important to detect donor's parameters affecting MSC potency. Age of the donors appears as one parameter that could greatly affect MSC properties. Moreover, in vitro cell expansion is needed to obtain the number of cells necessary for clinical developments. It will lead to in vitro cell aging that could modify cell properties. This review recapitulates several studies evaluating the effect of in vitro and in vivo MSC aging on cell properties.

Influence of mechanical stress on cell viability.

The cartilage is a hydrated connective tissue in joints that withstands and distributes mechanical forces. The chondrocytes utilize mechanical signals to regulate their metabolic activity through complex biological and biophysical interactions with the extracellular matrix (ECM). The aim of this work was to study the influence of mechanical stress on cells behavior cultured in 3D biosystems (alginate and alginate supplemented with hyaluronate). After mechanical stimulation, cell viability and cell death process were the main studied parameters. Our results indicated that viability and cell cycle progression were inhibited under mechanical stimulation, as far as the extracellular matrix was not yet synthesized. In contrast, on day 21, the mechanical stimulation had positive effect on these parameters.

IL-1beta synthesis by chondrocyte analyzed by 3D microscopy and flow cytometry: effect of Rhein.

Several factors are known to be involved in the destruction of the articular cartilage. Interleukin-1 (IL-1) plays an important role in the pathogenesis of osteoarthritis (OA) either directly or through the stimulation of catabolic factors. The action of IL-1 on articular cartilage is multifaceted and it most likely plays an important role in the mechanism of cartilage destruction. IL-1 suppresses the synthesis of the cartilage matrix components and promotes the degradation of cartilage matrix macromolecules. Diacerein is an anthraquinone molecule that has been shown to reduce the severity of OA, both in man and in animal models. The present study was designed to evaluate in vitro effects of diacerein on IL-1beta expression in LPS or IL-1alpha stimulated chondrocytes. Intracellular IL-1beta production was analysed in articular chondrocytes cultured in monolayer or in alginate 3D-biosystems in the presence of lipopolysaccharide (LPS) or IL-1alpha, with or without diacerein. The results show that LPS and IL-1alpha increase intracellular IL-1beta and Diacerein inhibited LPS-induced and IL-1alpha induced IL-1beta production by articular chondrocytes. Moreover, the effect of mechanical stimulation was analysed. An inhibitory effect of DAR at therapeutic concentrations on IL-1beta production in articular chondrocytes is suggested.

Stem cells and vascular regenerative medicine: A mini review.

Most human tissues do not regenerate spontaneously, which is why "cell therapy" are promising alternative treatments. The Principe is simple: patients' or donors' cells are collected and introduced into the injured tissues or organs directly or in a porous 3D material, with or without modification of their properties. This concept of regenerative medicine is an emerging field which can be defined as "the way to improve health and quality of life by restoring, maintaining, or enhancing tissue and organ functions".There is an extraordinarily wide range of opportunities for clinical applications: artheropathies, diabetes, cartilage defects, bone repair, burns, livers or bladder regeneration, organs reconstruction (lung, heart, liver ...) neurodegenerative disorders, sepsis ...  Different stem cells (SC) with different potential can be used and characterised (totipotent, mesenchymal of different origins, especially those present in tissues...). Today it is undeniable that cells like bone marrow, adipose tissue or Wharton Jelly stem cells, are of potential interest for clinical applications because they are easily separated and prepared and no ethical problems are involved in their use.In this paper some potential clinical applications in the vascular field are considered: peripheral arteriopathy in diabetic patients, cardiac insufficiency, traitment of erectile dysfunction, or organ regeneration with liver as example. But the regeneration of tissue or organ is and will remain a challenge for the future development of cell therapy. Many problems remain to be solved that could lead to the development of innovative strategies to facilitate cell differentiation, increase the yield of cells and ensure a standardised product, overcome the risks of teratogenic effects and/or immune reactions, enable grafting via direct cell or biotissue transplantation and avoid legal issues involved in national regulations.

Signalling pathways involved in the process of mesenchymal stem cells differentiating into hepatocytes.

End-stage liver disease can be the termination of acute or chronic liver diseases, with manifestations of liver failure; transplantation is currently an effective treatment for these. However, transplantation is severely limited due to the serious lack of donors, expense, graft rejection and requirement of long-term immunosuppression. Mesenchymal stem cells (MSCs) have attracted considerable attention as therapeutic tools as they can be obtained with relative ease and expanded in culture, along with features of self-renewal and multidirectional differentiation. Many scientific groups have sought to use MSCs differentiating into functional hepatocytes to be used in cell transplantation with liver tissue engineering to repair diseased organs. In most of the literature, hepatocyte differentiation refers to use of various additional growth factors and cytokines, such as hepatocyte growth factor (HGF), fibroblast growth factor (FGF), epidermal growth factor (EGF), oncostatin M (OSM) and more, and most are involved in signalling pathway regulation and cell-cell/cell-matrix interactions. Signalling pathways have been shown to play critical roles in embryonic development, tumourigenesis, tumour progression, apoptosis and cell-fate determination. However, mechanisms of MSCs differentiating into hepatocytes, particularly signalling pathways involved, have not as yet been completely illustrated. In this review, we have focused on progress of signalling pathways associated with mesenchymal stem cells differentiating into hepatocytes along with the stepwise differentiation procedure.

Stem Cells and Regenerative Medicine: Myth or Reality of the 21th Century.

Since the 1960s and the therapeutic use of hematopoietic stem cells of bone marrow origin, there has been an increasing interest in the study of undifferentiated progenitors that have the ability to proliferate and differentiate into various tissues. Stem cells (SC) with different potency can be isolated and characterised. Despite the promise of embryonic stem cells, in many cases, adult or even fetal stem cells provide a more interesting approach for clinical applications. It is undeniable that mesenchymal stem cells (MSC) from bone marrow, adipose tissue, or Wharton's Jelly are of potential interest for clinical applications in regenerative medicine because they are easily available without ethical problems for their uses. During the last 10 years, these multipotent cells have generated considerable interest and have particularly been shown to escape to allogeneic immune response and be capable of immunomodulatory activity. These properties may be of a great interest for regenerative medicine. Different clinical applications are under study (cardiac insufficiency, atherosclerosis, stroke, bone and cartilage deterioration, diabetes, urology, liver, ophthalmology, and organ's reconstruction). This review focuses mainly on tissue and organ regeneration using SC and in particular MSC.

Stem cells and applications: a survey.

Since the 1960s and the therapeutic use of hematopoietic stem cells of bone marrow origin, there has been increasing interest in the study of undifferentiated progenitors that have ability to proliferate and differentiate in different tissues. Different stem cells (SC) with different potential can be isolated and characterised. Despite the promise of embryonic stem cells, in many cases, adult stem cells provide a more interesting approach to clinical applications. It is undeniable that mesenchymal stem cells (MSC) from bone marrow, adipose tissue or MSC of Wharton Jelly, which have limited potential, are of interest for clinical applications in regenerative medicine because they are easily separated and prepared and no ethical problems are involved in their use.During the last 10 years, these multipotent cells have generated considerable interest and in particular have been shown to escape allogeneic immune response and be capable of immunomodulatory activity. These properties may be of a great interest for regenerative medicine. Different clinical applications are under study (cardiac insufficiency, atherosclerosis, stroke, bone, cartilage, diabetes, ophthalmology, urology, liver, organ's reconstruction…).

Characterization of monoclonal antibodies against human red blood group cells antigens by laser backscattering.

A problem in immunohematology is to define the antibody quality which is related to its affinity expressed by the equilibrium constant. The activity of an antibody can be measured by the strength of its interaction, related to the adhesive energy exchanged during RBC agglutination which depends on the antigen-antibody liaison strength. To estimate this adhesive energy, two methods are used in this paper. Firstly, the dissociation behaviour of suspended RBC agglutinates was analysed by laser backscattering intensity (r) in a Couette flow. Backscattered intensity issued from shear-induced mechanical dissociation is recorded and submitted to a numerical process to obtain the energy parameter (ED). Secondly, a modification of this technique is proposed for measuring specific binding energy. Samples were exposed to increasing shear stress, and backscattered intensity was recorded. A constant increase of this intensity with raising shear stress was observed, pointed to a progressive dissociation of RBC agglutinates into smaller ones. Considering that complete dissociation of agglutinates is only approached asymptotically it is assumed that the final break-up of doublets (two-cell agglutinates) is produced at a critical shear stress (tauC) reflecting the work done to breaking-up the molecular bridges between both adjacent cells. This shear stress is defined by the extrapolation of the linear part of the curves [r-log tau] to the backscattered signal (r0) corresponding to the complete dispersion of RBCs. These approaches permit to define the specific surface adhesive energy (Gamma) by using the Derjaguin relation and to assess the functional characterization of specific immunoglobulins. In conclusion, two parameters characterizing monoclonal antibody agglutination properties, ED and Gamma, were estimated by laser backscattering methods, which could be very useful for antibodies quality control.

Spectral and lifetime fluorescence imaging microscopies: new modalities of multiphoton microscopy applied to tissue or cell engineering.

Spectral and multiphoton imaging is the preferred approach for non-invasive study allowing deeper penetration to image molecular processes in living cells. But currently available fluorescence microscopic techniques based on fluorescence intensity, such as confocal or multiphoton excitation, cannot provide detailed quantitative information about the dynamic of complex cellular structure (molecular interaction). Due to the variation of the probe concentration, photostability, cross-talking, its effects cannot be distinguished in simple intensity images. Therefore, Time Resolved fluorescence image is required to investigate molecular interactions in biological systems. Fluorescence lifetimes are generally absolute, sensitive to environment, independent of the concentration of the probe and allow the use of probes with overlapping spectra but that not have the same fluorescence lifetime. In this work, we present the possibilities that are opened up by Fluorescence Lifetime Imaging Microscopy, firstly to collect images based on fluorescence lifetime contrast of GFP variants used as a reporter of gene expression in chondrocytes and secondly, to measure molecular proximity in erythrocyte (glycophorin/membrane) by Fluorescence Resonance Energy Transfer (FLIM-FRET).

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.