Combining xanthan and chitosan membranes to multipotent mesenchymal stromal cells as bioactive dressings for dermo-epidermal wounds

The association between tridimensional scaffolds to cells of interest has provided excellent perspectives for obtaining viable complex tissues in vitro, such as skin, resulting in impressive advances in the field of tissue engineering applied to regenerative therapies. The use of multipotent mesenchymal stromal cells in the treatment of dermo-epidermal wounds is particularly promising due to several relevant properties of these cells, such as high capacity of proliferation in culture, potential of differentiation in multiple skin cell types, important paracrine and immunomodulatory effects, among others. Membranes of chitosan complexed with xanthan may be potentially useful as scaffolds for multipotent mesenchymal stromal cells, given that they present suitable physico-chemical characteristics and have adequate tridimensional structure for the adhesion, growth, and maintenance of cell function. Therefore, the purpose of this work was to assess the applicability of bioactive dressings associating dense and porous chitosan-xanthan membranes to multipotent mesenchymal stromal cells for the treatment of skin wounds. The membranes showed to be non-mutagenic and allowed efficient adhesion and proliferation of the mesenchymal stromal cells in vitro. In vivo assays performed with mesenchymal stromal cells grown on the surface of the dense membranes showed acceleration of wound healing in Wistar rats, thus indicating that the use of this cell-scaffold association for tissue engineering purposes is feasible and attractive.

Chitosan-alginate membranes accelerate wound healing

The purpose of this study was to evaluate the efficacy of chitosan-alginate membrane to accelerate wound healing in experimental cutaneous wounds. Two wounds were performed in Wistar rats by punching (1.5 cm diameter), treated with membranes moistened with saline solution (CAM group) or with saline only (SL group). After 2, 7, 14, and 21 days of surgery, five rats of each group were euthanized and reepithelialization was evaluated. The wounds/scars were harvested for histological, flow cytometry, neutrophil infiltrate, and hydroxyproline analysis. CAM group presented higher inflammatory cells recruitment as compared to SL group on 2nd day. On the 7th day, CAM group showed higher CD11b+ level and lower of neutrophils than SL group. The CAM group presented higher CD4+ cells influx than SL group on 2nd day, but it decreased during the follow up and became lower on 14th and 21st days. Higher fibroplasia was noticed on days 7 and 14 as well as higher collagenesis on 21st in the CAM group in comparison to SL group. CAM group showed faster reepithelialization on 7th day than SL group, although similar in other days. In conclusion, chitosan-alginate membrane modulated the inflammatory phase, stimulated fibroplasia and collagenesis, accelerating wound healing process in rats.

Removal of glyphosate herbicide from water using biopolymer membranes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Antibacterial activity of alkyl gallates is a combination of direct targeting of FtsZ and permeabilization of bacterial membranes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Combining xanthan and chitosan membranes to multipotent mesenchymal stromal cells as bioactive dressings for dermo-epidermal wounds

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Transparent organic-inorganic nanocomposites membranes based on carboxymethylcellulose and synthetic clay

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chitosan-alginate membranes accelerate wound healing

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Thermal degradation of both latex and latex cast films forming membranes: combined TG/FTIR investigation

Latex collected from natural rubber trees forming membranes can be used as biomaterials in several fields being the temperature a key parameter. Thermogravimetry (TG) coupled to Fourier transform infrared spectroscopy (FTIR) is a useful technique to investigate the thermal degradation of both latex and cast films (membranes), wich were obtained from Hevea brasiliensis (RRIM 600 clone) and used without stabilization. The membranes were prepared by casting the latex onto a glass substrate at 65 degrees C for 6 h. The thermal degradation was followed by FTIR spectra acquisition along the process, allowing the identification of the gaseous components evolved upon the thermal treatment. According to TG measurements, the main processes of thermal degradation of the latex and membranes occur at three temperature intervals for both.

Cellulose acetate membranes for osmosedimentation: Performance and morphological dependence on preparation conditions

Osmosedimentation is a new membrane-assisted separation technique, based on the rapid approach to sedimentation equilibrium when macromolecular solutions are contained within dialysis cells, in contact with solvent via a permselective membrane. Cellulose acetate membranes, cast from ternary solvent (acetone, acetic acid, water) solutions are suitable for osmosedimentation of proteins at low (2000 rpm) centrifugation speeds. Solute retention is improved when acetone-rich casting solutions are used. These membranes were examined by electron and optical microscopy, showing considerable morphological changes in the membrane support layer as the casting solution composition is changed. © 1986.

Aging of intrauterine tissues in spontaneous preterm birth and preterm premature rupture of the membranes: a systematic review of the literature

Many adverse pregnancy outcomes (APOs), including spontaneous preterm birth (PTB), are associated with placental dysfunction. Recent clinical and experimental evidences suggest that premature aging of the placenta may be involved in these events. Although placental aging is a well-known concept, the mechanisms of aging during normal pregnancy and premature aging in APOs are still unclear. This review was conducted to assess the knowledge on placental aging related biochemical changes leading to placental dysfunction in PTB and/or preterm premature rupture of membranes (pPROM). We performed a systematic review of studies published over the last 50 years in two electronic databases (Pubmed and Embase) on placental aging and PTB or pPROM. The search yielded 554 citations, 30 relevant studies were selected for full-text review and three were included in the review. Only one study reported oxidative stress-related aging and degenerative changes in human placental membranes and telomere length reduction in fetal cells as part of PTB and/or pPROM mechanisms. Similarly, two animal studies reported findings of decidual senescence and referred to PTB mechanisms. Placental and fetal membrane oxidative damage and telomere reduction are linked to premature aging in PTB and pPROM but the risk factors and biomolecular pathways causing this phenomenon are not established in the literature. However, no biomarkers or clinical indicators of premature aging as a pathology of PTB and pPROM have been reported. We document major knowledge gaps and propose several areas for future research to improve our understanding of premature aging linked to placental dysfunction.

Imprinted gene expression in in vivo- And in vi/ro-produced bovine embryos and chorio-allantoic membranes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Bone defect repair on the alveolar wall of the maxillary sinus using collagen membranes and temporal fascia: an experimental study in monkeys

Few studies has been done using guided bone regeneration in maxillary sinus defects. AIM: To assess the bone repair process in surgical defects on the alveolar wall of the monkey maxillary sinus, which communicates with the sinus cavity, by using collagen membranes: Gen-derm - Genius Baumer, Pro-tape - Proline and autologous temporal fascia. MATERIALS AND METHODS: In this prospective and experimental study, orosinusal communications were performed in four tufted capuchin monkeys (Cebus apella) and histologic analysis was carried out 180 days after. RESULTS: In the defects without a cover (control), bone proliferation predominated in two animals and fibrous connective tissue predominated in the other two. In defects repaired with a temporal fascia flap, fibrous connective tissue predominated in three animals and bone proliferation predominated in one. In the defects repaired with Gen-derm or Pro-tape collagen membranes there was complete bone proliferation in three animals and fibrous connective tissue in one. CONCLUSIONS: Surgical defect can be repaired with both bone tissue and fibrous connective tissue in all study groups; collagen membranes was more beneficial in the bone repair process than temporal fascia or absence of a barrier.

Combining xanthan and chitosan membranes to multipotent mesenchymal stromal cells as bioactive dressings for dermo-epidermal wounds

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Poly(2,5-bibenzimidazole) Membranes: Physico-Chemical Characterization Focused on Fuel Cell Applications

Membranes of Poly(2,5-benzimidazole) (ABPBI), prepared by polycondensation in polyphosphoric acid, were characterized from the fuel cell application point of view: mechanical properties of the membranes for different acid doping levels, thermal stability, permeability for the different gases/vapors susceptible of use in the cell (hydrogen, oxygen, methanol and ethanol), electro-osmotic water drag coefficient, oxidation stability to hydroxyl radicals, phosphoric acid leaching rate and, finally, in-plane membrane conductivity. ABPBI membranes presented an excellent thermal stability, above 500 degrees C in oxygen, suitable mechanical properties for high phosphoric acid doping levels, a low methanol and ethanol limiting permeation currents, and oxygen permeability compared to Nafion membranes, and a low phosphoric acid leaching rate when exposed to water vapor. On the contrary, hydrogen permeation current was higher than that of Nafion, and the chemical stability was very limited. Membrane conductivity achieved 0.07 S cm(-1) after equilibration with a humid environment. Fuel cell tests showed reasonable good performances, with a maximum power peak of 170 mW cm(-2) for H-2/air at 170 degrees C operating under a humidified hydrogen stream, 39.9 mW cm(-2) for CH3OH/O-2 at 200 degrees C for a methanol/water weight ratio of 1: 2, and 31.5 mW cm(-2) for CH3CH2OH/O-2 at the same conditions than for methanol. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.014207jes] All rights reserved.