Functionalization of Titanium surface with Chitosan via silanation: 3D CLSM imaging of cell biocompatibility behaviour

Introduction Biocompatibility ranks as one of the most important properties of dental materials. One of the criteria for biocompatibility is the absence of material toxicity to cells, according to the ISO 7405 and 10993 recommendations. Among numerous available methods for toxicity assessment; 3-dimensional Confocal Laser Scanning Microscopy (3D CLSM) imaging was chosen because it provides an accurate and sensitive index of living cell behavior in contact with chitosan coated tested implants. Objectives: The purpose of this study was to investigate the in vitro biocompatibility of functionalized titanium with chitosan via a silanation using sensitive and innovative 3D CLSM imaging as an investigation method for cytotoxicity assessment. Methods The biocompatibility of four samples (controls cells, TA6V, TA6V-TESBA and TA6V-TESBAChitosan) was compared in vitro after 24h of exposure. Confocal imaging was performed on cultured human gingival fibroblast (HGF1) like cells using Live/Dead® staining. Image series were obtained with a FV10i confocal biological inverted system and analyzed with FV10-ASW 3.1 Software (Olympus France). Results Image analysis showed no cytotoxicity in the presence of the three tested substrates after 24 h of contact. A slight decrease of cell viability was found in contact with TA6V-TESBA with and without chitosan compared to negative control cells. Conclusion Our findings highlighted the use of 3D CLSM confocal imaging as a sensitive method to evaluate qualitatively and quantitatively the biocompatibility behavior of functionalized titanium with chitosan via a silanation. The biocompatibility of the new functionalized coating to HGF1 cells is as good as the reference in biomedical device implantation TA6V

Primary rat sertoli and interstitial cells exhibit a differential response to cadmium

Two cell types central to the support of spermatogenesis, the Sertoli cell and the interstitial (Leydig) cell, were isolated from the same cohort of young male rats and challenged with cadmium chloride to compare their susceptibility to the metal. Both cell types were cultured under similar conditions, and similar biochemical endpoints were chosen to minimize experimental variability. These endpoints include the uptake of 109 Cd, reduction of the vital tetrazolium dye MTT, incorporation of 3 H-leucine, change in heat-stable cadmium binding capacity, and production of lactate. Using these parameters, it was observed that the Sertoli cell cultures were adversely affected in a dose-and time-dependent manner, while the interstitial cell cultures, treated with identical concentrations of CdCl 2 , were less affected. The 72-hr LC 50 's for Sertoli cells and interstitial cells were 4.1 and 19.6 μM CdCl 2 , respectively. Thus, different cell populations within the same tissue may differ markedly in susceptibility to a toxicant. These in vitro data suggest that the Sertoli cell, in relation to the interstitium, is particularly sensitive to cadmium. Because the Sertoli cell provides functional support for the seminiferous epithelium, the differential sensitivity of this cell type may, in part, explain cadmium-induced testicular dysfunction, particularly at doses that leave the vascular epithelium intact.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42554/1/10565_2004_Article_BF00135027.pd

Localization of the Ca(2+)-binding alpha-parvalbumin and its mRNA in epiphyseal plate cartilage and bone of growing rats.

International audienceThis study describes the localization of alpha-parvalbumin, in undecalcified tibial epiphyseal cartilage and bone of growing rats by immunocytochemistry in the light microscope, and of parvalbumin mRNA by in situ hybridization. They were compared to the distribution of the calbindin-D9K and its mRNA in rat epiphyseal cartilage. All the chondrocytes of the epiphyseal cartilage were parvalbumin-immunopositive, but there was no parvalbumin immunoreactivity in the uncalcified or calcified extracellular cartilage matrix. The intensity of the immunostaining increased from the resting and proliferative to the mature and hypertrophic chondrocytes, with the greatest intensity in the terminal hypertrophic chondrocytes in the calcifying zone. The parvalbumin immunostaining was located in the cytoplasm, but no immunoreactivity was detected in any chondrocyte processes. The parvalbumin mRNA distribution and levels, as revealed by in situ hybridization, exactly mirrored those of the parvalbumin protein. In contrast to parvalbumin, calbindin-D9K and its mRNA appeared in mature chondrocytes and decreased in hypertrophic up to calcifying chondrocytes. Calbindin-D9K was located in the cytoplasm and all along the cell processes. In bone, the osteoblasts and the osteocytes of trabecular and compact cortical bones were immunoreactive for parvalbumin and contained parvalbumin mRNA. Parvalbumin lay in their cytoplasm, but there was no parvalbumin immunostaining in the extracellular uncalcified or mineralized bone matrix. The long processes of osteocytes, in compact bone only, were parvalbumin immunoreactive. Osteoclasts contained cytoplasmic parvalbumin immunoreactivity. Thus, the pattern of immunoreactive parvalbumin distribution indicates that the protein is not involved in the extracellular mineralization of cartilage and bone matrix. It appears to be associated with specific calcium-related intracellular functions in chondrocytes and in osteoblasts, osteocytes, and osteoclasts. As the highest cytoplasmic concentration of parvalbumin is in the terminal hypertrophic chondrocytes, parvalbumin could act as a calcium buffer to delay the death of chondrocytes. In compact bone, parvalbumin could also have a role throughout the osteocyte processes in regulating the fluxes of calcium ions for mineral homeostatis.This study describes the localization of alpha-parvalbumin, in undecalcified tibial epiphyseal cartilage and bone of growing rats by immunocytochemistry in the light microscope, and of parvalbumin mRNA by in situ hybridization. They were compared to the distribution of the calbindin-D9K and its mRNA in rat epiphyseal cartilage. All the chondrocytes of the epiphyseal cartilage were parvalbumin-immunopositive, but there was no parvalbumin immunoreactivity in the uncalcified or calcified extracellular cartilage matrix. The intensity of the immunostaining increased from the resting and proliferative to the mature and hypertrophic chondrocytes, with the greatest intensity in the terminal hypertrophic chondrocytes in the calcifying zone. The parvalbumin immunostaining was located in the cytoplasm, but no immunoreactivity was detected in any chondrocyte processes. The parvalbumin mRNA distribution and levels, as revealed by in situ hybridization, exactly mirrored those of the parvalbumin protein. In contrast to parvalbumin, calbindin-D9K and its mRNA appeared in mature chondrocytes and decreased in hypertrophic up to calcifying chondrocytes. Calbindin-D9K was located in the cytoplasm and all along the cell processes. In bone, the osteoblasts and the osteocytes of trabecular and compact cortical bones were immunoreactive for parvalbumin and contained parvalbumin mRNA. Parvalbumin lay in their cytoplasm, but there was no parvalbumin immunostaining in the extracellular uncalcified or mineralized bone matrix. The long processes of osteocytes, in compact bone only, were parvalbumin immunoreactive. Osteoclasts contained cytoplasmic parvalbumin immunoreactivity. Thus, the pattern of immunoreactive parvalbumin distribution indicates that the protein is not involved in the extracellular mineralization of cartilage and bone matrix. It appears to be associated with specific calcium-related intracellular functions in chondrocytes and in osteoblasts, osteocytes, and osteoclasts. As the highest cytoplasmic concentration of parvalbumin is in the terminal hypertrophic chondrocytes, parvalbumin could act as a calcium buffer to delay the death of chondrocytes. In compact bone, parvalbumin could also have a role throughout the osteocyte processes in regulating the fluxes of calcium ions for mineral homeostatis

Nanoplasmonics tuned “click chemistry”

Nanoplasmonics is a growing field of optical condensed matter science dedicated to optical phenomena at the nanoscale level in metal systems. Extensive research on noble metallic nanoparticles (NPs) has emerged within the last two decades due to their ability to keep the optical energy concentrated in the vicinity of NPs, in particular, the ability to create optical near-field enhancement followed by heat generation. We have exploited these properties in order to induce a localised “click” reaction in the vicinity of gold nanostructures under unfavourable experimental conditions. We demonstrate that this reaction can be controlled by the plasmonic properties of the nanostructures and we propose two physical mechanisms to interpret the observed plasmonic tuning of the “click” chemistry