Sodium Alginate-Quaternary Polymethacrylate Composites: Characterization of Dispersions and Calcium Ion Cross-Linked Gel Beads.

The objective of this work was to examine the effect of quaternary polymethacrylate (QPM), a water-insoluble polymer with a positive charge, on the characteristics of the sodium alginate (SA) dispersions and the calcium alginate (CA) gel beads containing propranolol HCl (PPN). The SA-QPM composite dispersions presented the formation of flocculates with a negative charge due to the electrostatic interaction of both substances. The QPM addition did not affect the SA dispersions' Newtonian flow, but the composite dispersions' viscosity enhancement was found. The PPN-loaded CA-QPM gel beads had more spherical than the PPN-loaded CA gel beads. The incorporation of QPM caused a bigger particle size, higher drug entrapment efficiency, and greater particle strength of the gel beads. Despite the similar water uptake property, the PPN-loaded CA-QPM gel beads displayed lower burst release and slower drug release rate than the PPN-loaded CA gel beads. However, the drug release from the PPN-loaded CA-QPM gel beads involved drug diffusion and matrix swelling mechanisms. This study demonstrated that adding QPM into the SA dispersions leads to a viscosity synergism. The CA-QPM gel beads display a good potential for use as a bioactive compound delivery system.

Prevention of acute graft-vs.-host disease by targeting glycolysis and mTOR pathways in activated T cells.

Graft-versus-host disease (GvHD) is a common life-threatening complication that can occur following allogeneic hematopoietic stem cell transplantation. This occurs if donor T cells recognize the host as foreign. During acute GvHD (aGVHD), activated T cells utilize glycolysis as the main source of energy generation. Therefore, inhibition of T cell glycolysis is a potential treatment strategy for aGVHD. In the present study, the effects of the combination of the glycolysis inhibitor 3-bromopyruvate (3-BrPA) and the mTOR inhibitor rapamycin (RAPA) on a mode of aGVHD were explored. In vitro mixed lymphocyte culture model was established by using splenocytes from C57BL/6 (H-2b) mice as responder and inactivated splenocytes from BALB/c (H-2d) mice as stimulator. In this model, 3-BrPA treatment (0-100 µmol/l) was found to suppress cell viability, increase cell apoptosis and reduce IFN-γ secretion, in a concentration-dependent manner. 3-BrPA treatment (0-100 µmol/l) was found to suppress cell viability, increase cell apoptosis and reduce IFN-γ secretion, in a concentration-dependent manner. In addition, combined treatment with 3-BrPA (0-100 µmol/l) alongside RAPA (20 µmol/l) exhibited synergistic effects on inhibiting cell viability and IFN-γ production, compared with those following either treatment alone. An aGVHD model was established by injection of bone marrow cells and spleen cells from the donor-C57BL/6(H-2b) mice to the receptor-BALB/c(H-2d) mice which were underwent total body irradiation first. In the aGVHD model, 3-BrPA (10 mg/kg/day), RAPA (2.5 and 5 mg/kg/day) and both in combination (5 and 2.5 mg/kg/day for 3-BrPA and RAPA, respectively) were all found to alleviate the damage caused by aGVHD, in addition to prolonging the survival time of mice with acute GvHD. In particular, the combined 3-BrPA and RAPA treatment resulted in the highest median survival time among all groups tested. In addition, the effects induced by combined 3-BrPA and RAPA treatment were found to be comparable to those in the 5 mg/kg/day RAPA group but superior to the 3-BrPA group with regards to the cumulative survival profile, GvHD score and lung histological score. The 3-BrPA and RAPA combination group also exhibited the lowest IFN-γ levels among all groups. Therefore, the combination of inhibiting both glycolysis and mTOR activity is a promising strategy for acute GvHD prevention.

Electroactive Gellan Gum/Polyaniline Spongy-Like Hydrogels.

The ability of electroactive materials to influence and modulate cell behavior has been revealing great potential, especially in the field of skeletal muscle tissue engineering. Herein, we propose PANi-GG electroactive spongy-like hydrogels as potential materials to modulate myoblast bioresponse. polyaniline (PANi) adds electroconductiviy to gellan gum (GG) spongy-like hydrogels that hold a high resemblance to the extracellular matrix (ECM), that is, water content, mechanical properties, and microarchitecture, and that can be further tuned to meet muscle tissue properties. For this purpose, PANi-GG spongy-like hydrogels were obtained by ionically cross-linking with calcium chloride (CaCl2) and further in situ aniline polymerization through oxidation with ammonium persulfate (APS) in a molar ratio of 1:1.05. The physicochemical characterization, surface morphology, electro-conductivity, and mechanical performance were assessed by FTIR, SEM, four-point probe technique, and compression testing, respectively. The viability and proliferation of L929 was not compromised after direct contact of PANi-GG spongy-like hydrogels with L929 cells, as determined by MTS assay and DNA quantification, respectively. C2C12 myoblasts were entrapped within the electroactive materials and cells adhered and spread. Moreover, cells proliferated along the cell culture period showing myosin expression after 7 days of culture. These results highlight that PANi-GG spongy like hydrogels are attractive candidates to be used in skeleton muscle tissue engineering.

Eumelanin Nanoparticle-Incorporated Polyvinyl Alcohol Nanofibrous Composite as an Electroconductive Scaffold for Skeletal Muscle Tissue Engineering.

Eumelanins are melanocyte-derived natural pigments with inherent electrical cues and outstanding physicochemical properties, which enhance the electroconductivity of the synthetic polymeric scaffold, upon incorporation as nanoparticles. Electrospun nanofibrous meshes generated from such composite polymers are of great interest for muscle tissue engineering applications. In this study, we investigated the feasibility of fabricating nanofibrous scaffolds of polyvinyl alcohol (PVA) incorporated with eumelanin nanoparticles (EUNp) by electrospinning and further assessed their impact on myogenic differentiation of skeletal myoblasts. Morphological and physicochemical analysis of EUNp-PVA nanofibrous mesh showed uniform, bead-free, thermally stable, and randomly oriented nanofibers (450 ± 10 nm) with effective retention of the incorporated EUNp, without any chemical cross-reactivity. Voltammetric measurements of EUNp-PVA mesh exhibits stable electrical conductivity (∼4.0 S cm-1), which was undetectable in plain PVA meshes. In vitrocytocompatibility studies showed a significant increase in viability, proliferation, and metabolic activity of the seeded C2C12 myoblast on EUNp-PVA mesh compared to controls. Interestingly, EUNp-PVA nanofibers supported reorganization of the C2C12 myoblast, with comparatively longer and wider myotube-like structures formed. Our results suggest that an EUNp-PVA composite nanofibrous scaffold with inherent electroconductive properties of incorporated EUNp and topographical cues of PVA nanofibers could be an excellent biomaterial scaffold for skeletal muscle tissue engineering applications.

* Synthesis and Characterization of Electroactive Gellan Gum Spongy-Like Hydrogels for Skeletal Muscle Tissue Engineering Applications.

Advances on materials' research for tissue engineering (TE) applications have shown that animal cells respond directly to the material physical, chemical, mechanical, and electrical stimuli altering a variety of cell signaling cascades, which consequently result in phenotypic and genotypic alterations. Gellan gum (GG) spongy-like hydrogels (SLH) with open microstructure, mechanical properties, and cell performance have shown promising results for soft TE applications. Taking advantage of intrinsic properties of GG-SLH and polypyrrole (PPy) electroactivity, we developed electroactive PPy-GG-SLH envisaging their potential use for skeletal muscle TE. Three different methods of in situ chemical oxidative polymerization were developed based on the availability of pyrrole: freely dissolved in solution (method I and III) or immobilized into GG hydrogels (method II). PPy was homogeneously distributed within (method I and III) and on the surface (method II) of GG-SLH, as also confirmed by Fourier Transform infrared spectra. PPy-GG-SLH showed higher conductivity than GG-SLH (p < 0.05) whereas PPy-GG-SLH (method I and II) showed the best conductivity among the 3 methods (∼1 to 2 × 10-4 S/cm). The microarchitecture of PPy-GG-SLH (method I) was similar to GG-SLH but PPy-GG-SLH (method II and III) presented smaller pore sizes and lower porosity. PPy-GG-SLH (method I and II) compressive modulus (∼450-500 KPa) and recovering capacity (∼75-90%) was higher than GG-SLH, nevertheless the mechanical properties of PPy-GG-SLH (method III) were lower. The water uptake of PPy-GG-SLH was rapidly up to 2500% and were stable along 60 days of degradation being the maximum weight loss 20%. Mechanically stable and electroactive PPy-GG-SLH (method I and II) were analyzed regarding cellular performance. PPy-GG-SLH were not cytotoxic for L929 cells. In addition, L929 and C2C12 myoblast cells were able to adhere and spread within PPy-GG-SLH, showing improved spreading in comparison to GG-SLH performance. Overall, PPy-GG-SLH show promising features as an alternative electroactive platform to analyze the influence of electrical stimulation on skeletal muscle cells.

Redox activity of melanin from the ink sac of Sepia officinalis by means of colorimetric oxidative assay.

The redox properties of natural extract from cuttlefish ink sac (Sepia officinalis) and synthetic melanin used as a biomimetic in melanin structural investigation were determined by comparison of this phenol-based heterogeneous pigment with gallic acid used as a standard in Folin-Ciocalteu colorimetric assay widely employed for characterisation of oxidative properties of biomaterials. Reactivity of sepia melanin reported here is much higher than previously indicated and this protocol should allow the redox characterisation of all melanins irrespective of their origin and composition.

Physico-chemical characteristics of methotrexate-entrapped oleic acid-containing deformable liposomes for in vitro transepidermal delivery targeting psoriasis treatment.

This study aimed to investigate the physico-chemical characteristics and in vitro permeability of methotrexate (MTX)-entrapped deformable liposomes prepared from phosphatidylcholine (PC) and oleic acid (OA), comparing with those of MTX-entrapped conventional liposomes prepared from PC and cholesterol (CH). Two formulations of MTX-entrapped PC2:CH1 and PC9:CH1 liposomes and one formulation of MTX-entrapped PC2.5:OA1 liposomes were prepared. The size, size distribution, zeta potential, thermal properties, entrapment efficiency, stability, and in vitro permeability across a porcine skin of the MTX-entrapped liposomes were evaluated. All liposome formulations showed a narrow size distribution with the size range of 80-140 nm which is appropriate for the skin permeability. The percentage of MTX loading, entrapment efficiency and the stability of MTX-entrapped PC2:CH1 and PC9:CH1 liposomes were slightly higher than those of MTX-entrapped PC2.5:OA1 liposomes. However, the MTX-entrapped PC2.5:OA1 liposomes enhanced the skin permeability characterized by the higher concentration and flux of MTX diffused across or accumulated in the epidermis and dermis layers of porcine skin. The enhanced permeability of MTX-entrapped PC2.5:OA1 liposomes was explained by 2 mechanisms: (1) the deformable and elasticity characteristics of OA-containing liposomes and (2) a property as a skin penetration enhancer of OA. This suggested that the PC2.5:OA1 deformable liposome was one of promising candidates to enhance the permeability of MTX for the treatment of psoriasis.