Comparative adsorption profiles of basal lamina proteome and gingival cells onto dental and titanium surfaces.

Titanium (Ti) dental implants are susceptible to bacterial infections and failure due to lack of proper epithelial seal. Epithelial cells establish a strong epithelial seal around natural teeth by the deposition of basal lamina (BL) proteins that adsorb on the tooth surface. This seal can even be re-established onto cementum or dentin following injury or periodontal therapy. However, it is unclear how tooth surfaces promote this cell attachment and protein adsorption. Understanding the interactions between BL proteins and epithelial cells with dentin and Ti will facilitate the development of implant surfaces that promote the formation of an epithelial seal and improve the success of periodontal therapy and wound healing on natural teeth. To study these interactions, we used a surface proteomic approach to decipher the adsorption profile of BL proteins onto Ti and dentin, and correlated these adsorption profiles with in vitro interactions of human gingival fibroblasts and epithelial cells. Results showed that dentin adsorbed higher amounts of key BL proteins, particularly laminin and nidogen-1, and promoted more favorable interactions with epithelial cells than Ti. Next, dentin specimens were deproteinized or partially demineralized to determine if its mineral or protein component was responsible for BL adsorption and cell attachment. Deproteinized (mineral-rich) and partially demineralized (protein-rich) dentin specimens revealed BL proteins (i.e. laminin and nidogen-1) and epithelial cells interact preferentially with dentinal proteins rather than dentin mineral. These findings suggest that, unlike Ti, dentin and, in particular, dentinal proteins have a selective affinity to BL proteins that enhance epithelial cell attachment. STATEMENT OF SIGNIFICANCE: It is remains unclear why natural teeth, unlike titanium dental implants, promote the formation of an epithelial seal that protects them against the external environment. This study used a surface screening approach to analyze the adsorption of proteins produced by epithelial tissues onto tooth-dentin and titanium surfaces, and correlate it with the behaviour of cells. This study shows that tooth-dentin, in particular its proteins, has a higher selective affinity to certain adhesion proteins, and subsequently allows more favourable interactions with epithelial cells than titanium. This knowledge could help in developing new approaches for re-establishing and maintaining the epithelial seal around teeth, and could pave the way for developing implants with surfaces that allow the formation of a true epithelial seal.

Biomaterial surface proteomic signature determines interaction with epithelial cells.

Cells interact with biomaterials indirectly through extracellular matrix (ECM) proteins adsorbed onto their surface. Accordingly, it could be hypothesized that the surface proteomic signature of a biomaterial might determine its interaction with cells. Here, we present a surface proteomic approach to test this hypothesis in the specific case of biomaterial-epithelial cell interactions. In particular, we determined the surface proteomic signature of different biomaterials exposed to the ECM of epithelial cells (basal lamina). We revealed that the biomaterial surface chemistry determines the surface proteomic profile, and subsequently the interaction with epithelial cells. In addition, we found that biomaterials with surface chemistries closer to that of percutaneous tissues, such as aminated PMMA and aminated PDLLA, promoted higher selective adsorption of key basal lamina proteins (laminins, nidogen-1) and subsequently improved their interactions with epithelial cells. These findings suggest that mimicking the surface chemistry of natural percutaneous tissues can improve biomaterial-epithelial integration, and thus provide a rationale for the design of improved biomaterial surfaces for skin regeneration and percutaneous medical devices. STATEMENT OF SIGNIFICANCE: Failure of most biomaterials originates from the inability to predict and control the influence of their surface properties on biological phenomena, particularly protein adsorption, and cellular behaviour, which subsequently results in unfavourable host response. Here, we introduce a surface-proteomic screening approach using a label-free mass spectrometry technique to decipher the adsorption profile of extracellular matrix (ECM) proteins on different biomaterials, and correlate it with cellular behaviour. We demonstrated that the way a biomaterial selectively interacts with specific ECM proteins of a given tissue seems to determine the interactions between the cells of that tissue and biomaterials. Accordingly, this approach can potentially revolutionize the screening methods for investigating the protein-cell-biomaterial interactions and pave the way for deeper understanding of these interactions.

A Molecular Necklace: Threading ß-Cyclodextrins onto Polymers Derived from Bile Acids.

A molecular necklace of polypseudorotaxanes was prepared by threading ß-cyclodextrins (ß-CD) onto biodegradable and thermoresponsive polyurethanes derived from bile acids. These polyurethanes were synthesized via a simple step condensation of bile acid-based dicarbonate with poly(ethylene glycol)-diamine. The ß-CD rings slide onto the poly(ethylene glycol) segments and selectively recognize the bile acid units of the polyurethane chains, whereas the poly(ethylene glycol) segments remain crystalline with a lower crystallinity. This bio-compound-derived molecular necklace can be visualized by scanning tunneling microscopy. The polypseudorotaxanes show thermosensitivity in water and the phase transition temperature may be fine-tuned by varying the molar ratios of ß-CD to the bile acid units. Such an interesting necklace model of polypseudorotaxane constructed from natural compounds may lead to the further exploration of their applications, such as as an enzyme model, due to their biological nature.

Assessing multidrug resistance protein 1-mediated function in cancer cell multidrug resistance by scanning electrochemical microscopy and flow cytometry.

Cancer cell multidrug resistance is a molecular signature that highly influences the outcome of chemotherapy treatment and for which there is currently no robust method to monitor in vitro its activity. Herein, we demonstrate that ferrocenemethanol (FcCH(2)OH) and its oxidized form ([FcCH(2)OH](+)) affect the redox state of cancer cells. Specifically, the interaction of FcCH(2)OH with the glutathione couple (GSH/GSSG) is shown in human adenocarcinoma cervical cancer cells HeLa and a multidrug resistant variant overexpressing the multidrug resistant associated protein 1 (MRP1) using bioanalytical techniques, such as flow cytometry and fluorescence microscopy. It is further demonstrated that the differential response to FcCH(2)OH in multidrug-resistant cells is in part due to MRP1's unspecific efflux. Scanning electrochemical microscopy confirmed the interaction between FcCH(2)OH and the cells, and the differential response was observed to depend on MRP1 expression. This newly established relation between FcCH(2)OH/[FcCH(2)OH](+), GSH/GSSG and multidrug resistance in human cancer cells enables than the acquisition of scanning electrochemical microscopy images.