Effect of Electrical Stimulation on PC12 Cells Cultured in Different Hydrogels: Basis for the Development of Biomaterials in Peripheral Nerve Tissue Engineering

Extensive damage to peripheral nerves is a health problem with few therapeutic alternatives. In this context, the development of tissue engineering seeks to obtain materials that can help recreate environments conducive to cellular development and functional repair of peripheral nerves. Different hydrogels have been studied and presented as alternatives for future treatments to emulate the morphological characteristics of nerves. Along with this, other research proposes the need to incorporate electrical stimuli into treatments as agents that promote cell growth and differentiation; however, no precedent correlates the simultaneous effects of the types of hydrogel and electrical stimuli. This research evaluates the neural differentiation of PC12 cells, relating the effect of collagen, alginate, GelMA, and PEGDA hydrogels with electrical stimulation modulated in four different ways. Our results show significant correlations for different cultivation conditions. Electrical stimuli significantly increase neural differentiation for specific experimental conditions dependent on electrical frequency, not voltage. These backgrounds allow new material treatment schemes to be formulated through electrical stimulation in peripheral nerve tissue engineering.

Osteoconductive Effect of a Nanocomposite Membrane Treated with UV Radiation

Modulation of the bio-regenerative characteristics of materials is an indispensable requirement in tissue engineering. Particularly, in bone tissue engineering, the promotion of the osteoconductive phenomenon determines the elemental property of a material be used therapeutically. In addition to the chemical qualities of the constituent materials, the three-dimensional surface structure plays a fundamental role that various methods are expected to modulate in a number of ways, one most promising of which is the use of different types of radiation. In the present manuscript, we demonstrate in a calvarial defect model, that treatment with ultraviolet irradiation allows modification of the osteoconductive characteristics in a biomaterial formed by gelatin and chitosan, together with the inclusion of hydroxyapatite and titanium oxide nanoparticles.

Anatase Incorporation to Bioactive Scaffolds Based on Salmon Gelatin and Its Effects on Muscle Cell Growth

The development of new polymer scaffolds is essential for tissue engineering and for culturing cells. The use of non-mammalian bioactive components to formulate these materials is an emerging field. In our previous work, a scaffold based on salmon gelatin was developed and tested in animal models to regenerate tissues effectively and safely. Here, the incorporation of anatase nanoparticles into this scaffold was formulated, studying the new composite structure by scanning electron microscopy, differential scanning calorimetry and dynamic mechanical analysis. The incorporation of anatase nanoparticles modified the scaffold microstructure by increasing the pore size from 208 to 239 µm and significantly changing the pore shape. The glass transition temperature changed from 46.9 to 55.8 °C, and an increase in the elastic modulus from 79.5 to 537.8 kPa was observed. The biocompatibility of the scaffolds was tested using C2C12 myoblasts, modulating their attachment and growth. The anatase nanoparticles modified the stiffness of the material, making it possible to increase the growth of myoblasts cultured onto scaffolds, which envisions their use in muscle tissue engineering.

Rheological and Structural Study of Salmon Gelatin with Controlled Molecular Weight

This study explores the molecular structuring of salmon gelatin (SG) with controlled molecular weight produced from salmon skin, and its relationship with its thermal and rheological properties. SG was produced under different pH conditions to produce samples with well-defined high (SGH), medium (SGM), and low (SGL) molecular weight. These samples were characterized in terms of their molecular weight (MW, capillary viscometry), molecular weight distribution (electrophoresis), amino acid profile, and Raman spectroscopy. These results were correlated with thermal (gelation energy) and rheological properties. SGH presented the higher MW (173 kDa) whereas SGL showed shorter gelatin polymer chains (MW < 65 kDa). Raman spectra and gelation energy suggest that amount of helical structures in gelatin is dependent on the molecular weight, which was well reflected by the higher viscosity and G' values for SGH. Interestingly, for all the molecular weight and molecular configuration tested, SG behaved as a strong gel (tan δ < 1), despite its low viscosity and low gelation temperature (3-10 °C). Hence, the molecular structuring of SG reflected directly on the thermal and viscosity properties, but not in terms of the viscoelastic strength of gelatin produced. These results give new insights about the relationship among structural features and macromolecular properties (thermal and rheological), which is relevant to design a low viscosity biomaterial with tailored properties for specific applications.

Re-Epithelialization Appraisal of Skin Wound in a Porcine Model Using a Salmon-Gelatin Based Biomaterial as Wound Dressing

The design of new functional materials for skin tissue engineering is an area of constant research. In this work, a novel wound-dressing biomaterial with a porous structure, previously formulated using salmon-gelatin as main component (called salmon-gelatin biomaterial (SGB)), was tested in vivo using pigs as skin wound models. Four weeks after cutaneous excision and implantation in the animals, the healing process did not show apparent symptoms of inflammation or infection. Interestingly, the temporal evolution of wound size from 100% to around 10% would indicate a faster recovery when SGB was compared against a commercial control. Histological analysis established that wounds treated with SGB presented similar healing and epithelialization profiles with respect to the commercial control. Moreover, vascularized granulation tissue and epithelialization stages were clearly identified, indicating a proliferation phase. These results showed that SGB formulation allows cell viability to be maintained. The latter foresees the development of therapeutic alternatives for skin repair based on SGB fabricated using low cost production protocols.

Isolation and identification of compounds from the resinous exudate of Escallonia illinita Presl. and their anti-oomycete activity

The resinous exudates from Escallonia illinita by products was characterized by FT-IR, NMR and HRMS. Six compounds were isolated and identified as follows: 1,5-diphenylpent-1-en-3-one (1), 4-(5-hydroxy-3,7-dimethoxy-4-oxo-4H-chromen-2-yl)phenyl acetate (2), pinocembrin (3), kaempferol 3-O-methylether (4), (3S,5S)-(E)-1,7-diphenylhept-1-ene-3,5-diol (5) and the new diarylheptanoid (3S,5S)-(E)-5-hydroxy-1,7-diphenylhept-1-en-3-yl acetate (6). The anti-oomycete potential of the resinous exudate, as well as the main compounds, was tested in vitro against Saprolegnia parasitica and Saprolegnia australis. The resinous exudate showed a strong anti-oomycete activity. In addition, the compounds 6, 1 and 3 demonstrated significant inhibition of Saprolegnia strains development. These findings strongly suggest that E. illinita is a potential biomass that could be used as a natural anti-oomycete product.

Synthesis and Antiproliferative Activity of New Cyclodiprenyl Phenols against Select Cancer Cell Lines

Six new cyclodiprenyl phenols were synthesized by direct coupling of perillyl alcohol and the appropriate phenol. Their structures were established by IR, HRMS and mainly NMR. Three human cancer cell lines-breast (MCF-7), prostate (PC-3) and colon (HT-29)-were used in antiproliferative assays, with daunorubicin and dunnione as positive controls. Results described in the article suggest that dihydroxylated compounds 2⁻4 and monohydroxylated compound 5 display selectivity against cancer cell lines, cytotoxicity, apoptosis induction, and mitochondrial membrane impairment capacity. Compound 2 was identified as the most effective of the series by displaying against all cancer cell lines a cytotoxicity close to dunnione antineoplastic agent, suggesting that the cyclodiprenyl phenols from perillyl alcohol deserve more extensive investigation of their potential medicinal applications.

Biopesticide Activity from Drimanic Compounds to Control Tomato Pathogens

Tomato crops can be affected by several infectious diseases produced by bacteria, fungi, and oomycetes. Four phytopathogens are of special concern because of the major economic losses they generate worldwide in tomato production; Clavibacter michiganensis subsp. michiganensis and Pseudomonas syringae pv. tomato, causative agents behind two highly destructive diseases, bacterial canker and bacterial speck, respectively; fungus Fusarium oxysporum f. sp. lycopersici that causes Fusarium Wilt, which strongly affects tomato crops; and finally, Phytophthora spp., which affect both potato and tomato crops. Polygodial (1), drimenol (2), isonordrimenone (3), and nordrimenone (4) were studied against these four phytopathogenic microorganisms. Among them, compound 1, obtained from Drimys winteri Forst, and synthetic compound 4 are shown here to have potent activity. Most promisingly, the results showed that compounds 1 and 4 affect Clavibacter michiganensis growth at minimal inhibitory concentrations (MIC) values of 16 and 32 µg/mL, respectively, and high antimycotic activity against Fusarium oxysporum and Phytophthora spp. with MIC of 64 µg/mL. The results of the present study suggest novel treatment alternatives with drimane compounds against bacterial and fungal plant pathogens.

Edible Scaffolds Based on Non-Mammalian Biopolymers for Myoblast Growth

In vitro meat has recently emerged as a new concept in food biotechnology. Methods to produce in vitro meat generally involve the growth of muscle cells that are cultured on scaffolds using bioreactors. Suitable scaffold design and manufacture are critical to downstream culture and meat production. Most current scaffolds are based on mammalian-derived biomaterials, the use of which is counter to the desire to obviate mammal slaughter in artificial meat production. Consequently, most of the knowledge is related to the design and control of scaffold properties based on these mammalian-sourced materials. To address this, four different scaffold materials were formulated using non-mammalian sources, namely, salmon gelatin, alginate, and additives including gelling agents and plasticizers. The scaffolds were produced using a freeze-drying process, and the physical, mechanical, and biological properties of the scaffolds were evaluated. The most promising scaffolds were produced from salmon gelatin, alginate, agarose, and glycerol, which exhibited relatively large pore sizes (~200 μm diameter) and biocompatibility, permitting myoblast cell adhesion (~40%) and growth (~24 h duplication time). The biodegradation profiles of the scaffolds were followed, and were observed to be less than 25% after 4 weeks. The scaffolds enabled suitable myogenic response, with high cell proliferation, viability, and adequate cell distribution throughout. This system composed of non-mammalian edible scaffold material and muscle-cells is promising for the production of in vitro meat.

Hemi-Synthesis and Anti-Oomycete Activity of Analogues of Isocordoin

An efficient synthesis of a series of 4′-oxyalkyl-isocordoin analogues (2–8) is reported for the first time. Their structures were confirmed by ¹H-NMR, ¹³C-NMR, and HRMS. Their anti-oomycete activity was evaluated by mycelium and spores inhibition assay against two selected pathogenic oomycetes strains: Saprolegnia parasitica and Saprolegnia australis. The entire series of isocordoin derivatives (except compound 7) showed high inhibitory activity against these oomycete strains. Among them, compound 2 exhibited strong activity, with minimum inhibitory concentration (MIC) and minimum oomyceticidal concentration (MOC) values of 50 µg/mL and 75 µg/mL, respectively. The results showed that 4′-oxyalkylated analogues of isocordoin could be potential anti-oomycete agents.

The effects of lipids and surfactants on TLR5-proteoliposome functionality for flagellin detection using surface plasmon resonance biosensing

The use of proteoliposomes as affinity elements in conjunction with a surface plasmon resonance sensor is a high-sensitivity alternative for the detection of multiple analytes. However, one of the most important aspects of these conformations is maintaining the functionality of the immobilized protein, which is determined by the choice of lipids and surfactants employed in the reconstitutions. Previously, we demonstrated the functionality of TLR5-proteoliposomes as screening affinity elements of bacterial flagellin. In this new study we change the conditions of immobilization of TLR5 and evaluate how the fluidity of the membrane and the final size of the liposomes affect the functionality of the construct and thus increase their utility as an affinity element for design of new biosensors. In particular, we used reconstructions into preformed liposomes composed of the lipids POPC, POPC-DMPC and POPC-POPE mediated by the use of surfactants OG, Triton X100, and DDM, respectively. The affinity results were evaluated by SPR technology proteoliposomes and were correlated with the anisotropic change in the membrane status; the final sizes of the proteoliposomes were estimated. Our results clearly show the dependence of fluidity and final size of the proteoliposomes with surface plasmon resonance affinity measurements.