An innovative synthesis of carbon-coated TiO2 nanoparticles as a host for Na+ intercalation in sodium-ion batteries.

In this work, an innovative route to synthesize an anatase TiO2@C composite is presented. The synthesis was conducted using a soft chemistry microwave-assisted method using titanium(IV) butoxide as a titanium precursor. The residual (un)converted titanium precursor remaining after TiO2 synthesis was used as a carbon precursor and thermally treated under H2 to obtain nanoparticles of the TiO2@C composite. A superior reversible specific capacity was obtained with TiO2@C (120 mA h g-1 at a C/20 rate, 3rd cycle) compared to that with pristine TiO2 (66.5 mA h g-1 at a C/20 rate, 3rd cycle), in agreement with the importance of carbon coating addition to TiO2 nanoparticles as negative electrode materials for sodium-ion batteries.

Insights into Solid-To-Solid Transformation of MOF Amorphous Phases.

Metal-organic frameworks (MOFs) have been recently explored as crystalline solids for conversion into amorphous phases demonstrating non-specific mechanical, catalytic, and optical properties. The real-time control of such structural transformations and their outcomes still remain a challenge. Here, we use in situ high-resolution transmission electron microscopy with 0.01 s time resolution to explore non-thermal (electron induced) amorphization of a MOF single crystal, followed by transformation into an amorphous nanomaterial. By comparing a series of M-BTC (M: Fe3+, Co3+, Co2+, Ni2+, and Cu2+; BTC: 1,3,5-benzentricarboxylic acid), we demonstrate that the topology of a metal cluster of the parent MOFs determines the rate of formation and the chemistry of the resulting phases containing an intact ligand and metal or metal oxide nanoparticles. Confocal Raman and photoluminescence spectroscopies further confirm the integrity of the BTC ligand and coordination bond breaking, while high-resolution imaging with chemical and structural analysis over time allows for tracking the dynamics of solid-to-solid transformations. The revealed relationship between the initial and resulting structures and the stability of the obtained phase and its photoluminescence over time contribute to the design of new amorphous MOF-based optical nanomaterials.

Pro-apoptotic effect of Δ2-TGZ in "claudin-1-low" triple-negative breast cancer cells: involvement of claudin-1.

PURPOSE: 40% of triple-negative breast cancer (TNBC) do not express claudin-1, a major constituent of tight junction. Patients with these "claudin-1-low" tumors present a higher relapse incidence. A major challenge in oncology is the development of innovative therapies for such poor prognosis tumors. In this context, we study the anticancer effects of ∆2-TGZ, a compound derived from troglitazone (TGZ), on cell models of these tumors. METHODS AND RESULTS: In MDA-MB-231 and Hs578T "claudin-1-low" TNBC cells, Δ2-TGZ treatment induced claudin-1 protein expression and triggered apoptosis as measured by FACS analysis (annexin V/PI co-staining). Interestingly, in the non-tumorigenic human breast epithelial cell line MCF-10A, the basal level of claudin-1 was not modified following Δ2-TGZ treatment, which did not induce apoptosis. Furthermore, claudin-1-transfected MDA-MB-231 and Hs578T cells displayed a significant increase of cleaved PARP-1 and caspase 7, caspase 3/7 activities, and TUNEL staining. RNA interference was performed in order to inhibit Δ2-TGZ-induced claudin-1 expression in both the cells. In absence of claudin-1, a decrease of cleaved PARP-1 and caspase 7 and caspase 3/7 activities were observed in MDA-MB-231 but not in Hs578T cells. CONCLUSION: Claudin-1 overexpression and Δ2-TGZ treatment are associated to apoptosis in MDA-MB-231 and Hs578T "claudin-1-low" TNBC. Moreover, in MDA-MB-231 cells, claudin-1 is involved in the pro-apoptotic effect of Δ2-TGZ. Our results suggest that claudin-1 re-expression could be an interesting therapeutic strategy for "claudin-1-low" TNBC.

Umbilical cord-derived mesenchymal stromal cells: predictive obstetric factors for cell proliferation and chondrogenic differentiation.

BACKGROUND: The umbilical cord is becoming a notable alternative to bone marrow (BM) as a source of mesenchymal stromal cells (MSC). Although age-dependent variations in BM-MSC are well described, less data are available for MSC isolated from Wharton's jelly (WJ-MSC). We initiated a study to identify whether obstetric factors influenced MSC properties. We aimed to evaluate the correlation between a large number of obstetric factors collected during pregnancy and until peripartum (related to the mother, the labor and delivery, and the newborn) with WJ-MSC proliferation and chondrogenic differentiation parameters. METHODS: Correlations were made between 27 obstetric factors and 8 biological indicators including doubling time at passage (P)1 and P2, the percentage of proteoglycans and collagens, and the relative transcriptional expression of Sox-9, aggrecans, and total type 2 collagen (Coll2T). RESULTS: Amongst the obstetric factors considered, birth weight, the number of amenorrhea weeks, placental weight, normal pregnancy, and the absence of preeclampsia were identified as relevant factors for cell expansion, using multivariate linear regression analysis. Since all the above parameters are related to term, we concluded that WJ-MSC from healthy, full-term infants exhibit greater proliferation capacity. As for chondrogenesis, we also observed that obstetric factors influencing proliferation seemed beneficial, with no negative impact on MSC differentiation. CONCLUSIONS: Awareness of obstetric factors influencing the proliferation and/or differentiation of WJ-MSC will make it possible to define criteria for collecting optimal umbilical cords with the aim of decreasing the variability of WJ-MSC batches produced for clinical use in cell and tissue engineering.

Effect of nicotine on the proliferation and chondrogenic differentiation of the human Wharton's jelly mesenchymal stem cells.

BACKGROUND: Osteoarthritis (OA) is a chronic joint disease characterized by a progressive and irreversible degeneration of articular cartilage. Among the environmental risk factors of OA, tobacco consumption features prominently, although, there is a great controversy regarding the role of tobacco smoking in OA development. Among the numerous chemicals present in cigarette smoke, nicotine is one of the most physiologically active molecules. OBJECTIVE: The aim of the study was (i) to measure the impact of nicotine on the proliferation and chondrogenic differentiation of mesenchymal stem cells from the human Wharton's jelly (hWJ-MSCs) into chondrocytes, (ii) to investigate whether the α7 nicotinic acetylcholine receptors (nAChRs) was expressed in hWJ-MSCs and could play a role in the process. The project benefits from the availability of an umbilical cord bank from which hWJ-MSCs were originated. METHODS: The hWJ-MSCs were cultured and used up to passage 5. The proliferation of hWJ-MSCs with 5 µM nicotine was measured by the MTT assay on the 1st, 2nd, 3rd, and 6th day. Flow cytometry analysis was used to detect cell apoptosis/necrosis by Annexin V/PI double-staining. The chondrogenic differentiation grade of hWJ-MSCs induced by TGFß3 was assessed by the Sirius red and Alcian blue staining. The expression of markers genes was followed by quantitative real-time PCR. The expression of nAChRs was followed by RT-PCR. The functional activity of α7 nAChR was evaluated by calcium (Ca2+) influx mediated by nicotine using the Fluo-4 NW Calcium assay. RESULTS: The proliferation of hWJ-MSCs was significantly impaired by nicotine (5 µM) from the 3rd day of treatment, but nicotine did not significantly induce modifications on the viability of hWJ-MSCs. Alcian blue staining indicated that the amount of proteoglycan was more abundant in control group than in the nicotine group, but no difference was observed on the total collagen amount using Sirius red staining. The mRNA expression of Sox9, type II collagen (Col2a1), aggrecan in control group was higher than in the nicotine group. We found that hWJ-MSCs expressed α7 nAChR. The receptor agonist nicotine caused calcium (Ca2+) influx into hWJ-MSCs suggesting that the calcium ion channel α7 homopolymer could mediate this response. CONCLUSIONS: At the concentration used, nicotine had an adverse effect on the proliferation and chondrogenic differentiation of hWJ-MSCs which was probably impaired through a α7 nAChR mediation.

New tools for non-invasive exploration of collagen network in cartilaginous tissue-engineered substitute.

In tissue engineering approaches, the quality of substitutes is a key element to determine its ability to treat cartilage defects. However, in clinical practice, the evaluation of tissue-engineered cartilage substitute quality is not possible due to the invasiveness of the standard procedure, which is to date histology. The aim of this work was to validate a new innovative system performed from two-photon excitation laser adapted to an optical macroscope to evaluate at macroscopic scale the collagen network in cartilage tissue-engineered substitutes in confrontation with gold standard histologic techniques or immunohistochemistry to visualize type II collagen. This system permitted to differentiate the quality of collagen network between ITS and TGF-ß1 treatments. Multiscale large field imaging combined to multimodality approaches (SHG-TCSPC) at macroscopical scale represent an innovative and non-invasive technique to monitor the quality of collagen network in cartilage tissue-engineered substitutes before in vivo implantation.

DDB2 (damaged-DNA binding 2) protein: a new modulator of nanomechanical properties and cell adhesion of breast cancer cells.

DDB2, known for its role in DNA repair, was recently shown to reduce mammary tumor invasiveness by inducing the transcription of IκBα, an inhibitor of NF-κB activity. Since cellular adhesion is a key event during the epithelial to mesenchymal transition (EMT) leading to the invasive capacities of breast tumor cells, the aim of this study was to investigate the role of DDB2 in this process. Thus, using low and high DDB2-expressing MDA-MB231 and MCF7 cells, respectively, in which DDB2 expression was modulated experimentally, we showed that DDB2 overexpression was associated with a decrease of adhesion abilities on glass and plastic areas of breast cancer cells. Then, we investigated cell nanomechanical properties by atomic force microscopy (AFM). Our results revealed significant changes in the Young's Modulus value and the adhesion force in MDA-MB231 and MCF7 cells, whether DDB2 was expressed or not. The cell stiffness decrease observed in MDA-MB231 and MCF7 expressing DDB2 was correlated with a loss of the cortical actin-cytoskeleton staining. To understand how DDB2 regulates these processes, an adhesion-related gene PCR-Array was performed. Several adhesion-related genes were differentially expressed according to DDB2 expression, indicating that important changes are occurring at the molecular level. Thus, this work demonstrates that AFM technology is an important tool to follow cellular changes during tumorigenesis. Moreover, our data revealed that DDB2 is involved in early events occurring during metastatic progression of breast cancer cells and will contribute to define this protein as a new marker of metastatic progression in this type of cancer.

Enhanced SRSF5 Protein Expression Reinforces Lamin A mRNA Production in HeLa Cells and Fibroblasts of Progeria Patients.

The Hutchinson Gilford Progeria Syndrome (HGPS) is a rare genetic disease leading to accelerated aging. Three mutations of the LMNA gene leading to HGPS were identified. The more frequent ones, c.1824C>T and c.1822G>A, enhance the use of the intron 11 progerin 5'splice site (5'SS) instead of the LMNA 5'SS, leading to the production of the truncated dominant negative progerin. The less frequent c.1868C>G mutation creates a novel 5'SS (LAΔ35 5'SS), inducing the production of another truncated LMNA protein (LAΔ35). Our data show that the progerin 5'SS is used at low yield in the absence of HGPS mutation, whereas utilization of the LAΔ35 5'SS is dependent upon the presence of the c.1868C>G mutation. In the perspective to correct HGPS splicing defects, we investigated whether SR proteins can modify the relative yields of utilization of intron 11 5'SSs. By in cellulo and in vitro assays, we identified SRSF5 as a direct key regulator increasing the utilization of the LMNA 5'SS in the presence of the HGPS mutations. Enhanced SRSF5 expression in dermal fibroblasts of HGPS patients as well as PDGF-BB stimulation of these cells decreased the utilization of the progerin 5'SS, and improves nuclear morphology, opening new therapeutic perspectives for premature aging.

Hypoxic culture conditions for Mesenchymal Stromal/Stem Cells from Wharton's jelly: a critical parameter to consider in a therapeutic context.

Mesenchymal Stromal/Stem Cells from human Wharton's jelly (WJ-MSC) are an abundant and interesting source of stem cells for applications in cell and tissue engineering. Their fetal origin confers specific characteristics compared to Mesenchymal Stromal/Stem Cells isolated from human bone marrow (BM-MSC). The aim of this work was to optimize WJ-MSC culture conditions for their subsequent clinical use. We focused on the influence of oxygen concentration during monolayer expansion on several parameters to characterize MSC. Our work distinguished WJ-MSC from BM-MSC in terms of proliferation, telomerase activity and adipogenic differentiation. We also showed that hypoxia had a beneficial effect on proliferation potential, clonogenic capacity and to a lesser extent, on HLA-G expression of WJ-MSC during their expansion. Moreover, we reported for the first time an increase in chondrogenic differentiation when WJ-MSC were expanded under hypoxia. In an allogeneic therapeutic context, production of clinical batches requires generating high numbers of MSC whilst maintaining the cells' properties. Considering our results, hypoxia will be an important parameter to take into account. In addition, the clinical use of WJ-MSC would provide significant numbers of cells with maintenance of their proliferation and differentiation potential, particularly their chondrogenic potential. Due to their chondrogenic differentiation potential, WJ-MSC promise to be an interesting source of MSC for cell therapy or tissue engineering for cartilage repair and/or regeneration.

Photodynamic therapy with conventional and PEGylated liposomal formulations of mTHPC (temoporfin): comparison of treatment efficacy and distribution characteristics in vivo.

A major challenge in the application of a nanoparticle-based drug delivery system for anticancer agents is the knowledge of the critical properties that influence their in vivo behavior and the therapeutic performance of the drug. The effect of a liposomal formulation, as an example of a widely-used delivery system, on all aspects of the drug delivery process, including the drug's behavior in blood and in the tumor, has to be considered when optimizing treatment with liposomal drugs, but that is rarely done. This article presents a comparison of conventional (Foslip®) and polyethylene glycosylated (Fospeg®) liposomal formulations of temoporfin (meta-tetra[hydroxyphenyl]chlorin) in tumor-grafted mice, with a set of comparison parameters not reported before in one model. Foslip® and Fospeg® pharmacokinetics, drug release, liposome stability, tumor uptake, and intratumoral distribution are evaluated, and their influence on the efficacy of the photodynamic treatment at different light-drug intervals is discussed. The use of whole-tumor multiphoton fluorescence macroscopy imaging is reported for visualization of the in vivo intratumoral distribution of the photosensitizer. The combination of enhanced permeability and retention-based tumor accumulation, stability in the circulation, and release properties leads to a higher efficacy of the treatment with Fospeg® compared to Foslip®. A significant advantage of Fospeg® lies in a major decrease in the light-drug interval, while preserving treatment efficacy.

Osteogenic differentiation of human bone marrow mesenchymal stem cells in hydrogel containing nacre powder.

Nacre (or mother of pearl) can facilitate bone cell differentiation and can speed up their mineralization. Here we report on the capability of nacre to induce differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs) and the production of extracellular matrix. hBM-MSCs were encapsulated in an alginate hydrogel containing different concentrations of powdered nacre and cultured in the same environment until Day 28. Analysis of osteogenic gene expression, histochemistry, second harmonic generation (SHG) microscopy, and Raman scattering spectroscopy were used to characterize the synthesis of the extracellular matrix. In the presence of nacre powder, a significant increase in matrix synthesis from D21 in comparison with pure alginate was observed. Histochemistry revealed the formation of a new tissue composed of collagen fibers in the presence of nacre (immunostaining and SHG), and hydroxyapatite crystals (Raman) in the alginate beads. These results suggest that nacre is efficient in hBM-MSCs differentiation, extracellular matrix production and mineralization in alginate 3D biomaterials.