Electrospun chitosan-graft-poly (ε -caprolactone)/poly (ε-caprolactone) cationic nanofibrous mats as potential scaffolds for skin tissue engineering

This research is aimed to develop cationic nanofibrous mats with improved cellular adhesion profiles and stability of three-dimensional fibrous structure as potential scaffolds for skin tissue engineering. Firstly, amino-remained chitosan-graft-poly (?-caprolactone) (CS-g-PCL) was synthesized with a facile one-step manner by grafting ?-caprolactone oligomers onto the hydroxyl groups of CS via ring-opening polymerization by using methanesulfonic acid as solvent and catalyst. And then, CS-g-PCL/PCL nanofibrous mats were obtained by electrospinning of CS-g-PCL/PCL mixed solution. Scanning electron microscopy (SEM) images showed that the morphologies and diameters of the nanofibers were mainly affected by the weight ratio of CS-g-PCL to PCL. The enrichment of amino groups on the nanofiber surface was confirmed by X-ray photoelectron spectroscopy (XPS). With the increase of CS-g-PCL in CS-g-PCL/PCL nanofiber, the content of amino groups on the nanofiber surface increased, which resulted in the increase of zeta-potential of nanofibers. Studies on cell-scaffold interaction were carried out by culturing mouse fibroblast cells (L929) on CS-g-PCL/PCL nanofibrous mats with various contents of CS-g-PCL by assessing the growth, proliferation and morphologies of cells. The results of MTS assay and SEM observation showed that CS-g-PCL/PCL (2/8) mats with a moderate surface zeta-potential (ζ=3mV) were the best in promoting the cell attachment and proliferation. Toluidine blue staining further confirmed that L929 cells grew well and exhibited a normal morphology on the CS-g-PCL/PCL (2/8) mats. These results suggested the potential utilization of CS-g-PCL/PCL (2/8) nanofibrous mats for skin tissue engineering.     

Physiologically clotted fibrin – Preparation and characterization for tissue engineering and drug delivery applications

Fibrin used for biomedical applications is prepared by mixing concentrated solutions of fibrinogen and thrombin in presence of cross-linking agents such as Factor XIII or glutaraldehyde. The main drawbacks associated with this procedure include cost, complexity and time required for fibrin preparation. Hence, present study deals with the characterization of physiologically clotted fibrin (PF) for bone tissue engineering and drug delivery applications. For this the physico-chemical properties of PF were compared with those of the conventionally prepared fibrin (CF). Further MTT and haemolytic assays were performed for both PF and CF to compare their biocompatibility. The amount of alkaline phosphatase produced and calcium secreted by MG-63 cells in the presence of PF and CF were used to relate the osteogenic potency of PF with that of CF. Gallic acid, an anti-cancer drug was loaded within PF and CF and their role in drug delivery was compared.     

Bioreactors in tissue engineering—principles,applications and commercial constraints

Bioreactor technology is vital for tissue engineering. Usually, bioreactors are used to provide a tissue-specific physiological in vitro environment during tissue maturation. In addition to this most obvious application, bioreactors have the potential to improve the efficiency of the overall tissue-engineering concept. To date, a variety of bioreactor systems for tissue-specific applications have been developed. Of these, some systems are already commercially available. With bioreactor technology, various functional tissues of different types were generated and cultured in vitro. Nevertheless, these efforts and achievements alone have not yet led to many clinically successful tissue-engineered implants. We review possible applications for bioreactor systems within a tissue-engineering process and present basic principles and requirements for bioreactor development. Moreover, the use of bioreactor systems for the expansion of clinically relevant cell types is addressed. In contrast to cell expansion, for the generation of functional three-dimensional tissue equivalents, additional physical cues must be provided. Therefore, bioreactors for musculoskeletal tissue engineering are discussed. Finally, bioreactor technology is reviewed in the context of commercial constraints.     

Physiological implications of SWEETs in plants and their potential applications in improving source–sink relationships for enhanced yield

The sugars will eventually be exported transporters (SWEET) family of transporters in plants is identified as a novel class of sugar carriers capable of transporting sugars, sugar alcohols and hormones. Functioning in intercellular sugar transport, SWEETs influence a wide range of physiologically important processes. SWEETs regulate the development of sink organs by providing nutritional support from source leaves, responses to abiotic stresses by maintaining intracellular sugar concentrations, and host–pathogen interactions through the modulation of apoplastic sugar levels. Many bacterial and fungal pathogens activate the expression of SWEET genes in species such as rice and Arabidopsis to gain access to the nutrients that support virulence. The genetic manipulation of SWEETs has led to the generation of bacterial blight (BB)-resistant rice varieties. Similarly, while the overexpression of the SWEETs involved in sucrose export from leaves and pathogenesis led to growth retardation and yield penalties, plants overexpressing SWEETs show improved disease resistance. Such findings demonstrate the complex functions of SWEETs in growth and stress tolerance. Here, we review the importance of SWEETs in plant–pathogen and source–sink interactions and abiotic stress resistance. We highlight the possible applications of SWEETs in crop improvement programmes aimed at improving sink and source strengths important for enhancing the sustainability of yield. We discuss how the adverse effects of the overexpression of SWEETs on plant growth may be overcome.     

Novel PKCα-mediated phosphorylation site(s) on cofilin and their potential role in terminating histamine release

Using specific inhibitors, kinase-negative mutants, and small interfering RNA against protein kinase Cα (PKCα) or PKCβI, we find that PKCβI positively regulates degranulation in rat basophilic leukemia-2H3 cells, whereas PKCα negatively regulates degranulation. Mass spectrometric and mutagenic analyses reveal that PKCα phosphorylates cofilin at Ser-23 and/or Ser-24 during degranulation. Overexpression of a nonphosphorylatable form (S23,24A), but not that of a mutant-mimicking phosphorylated form (S23,24E), increases degranulation. Furthermore, the S23,24A mutant binds to F-actin and retains its depolymerizing and/or cleavage activity; conversely, the S23,24E mutant is unable to sever actin filaments, resulting in F-actin polymerization. In addition, the S23,24E mutant preferentially binds to the 14-3-3ζ protein. Fluorescence-activated cell sorting analysis with fluorescein isothiocyanate-phalloidin and simultaneous observation of degranulation, PKC translocation, and actin polymerization reveals that during degranulation, actin polymerization is dependent on PKCα activity. These results indicate that a novel PKCα-mediated phosphorylation event regulates cofilin by inhibiting its ability to depolymerize F-actin and bind to 14-3-3ζ, thereby promoting F-actin polymerization, which is necessary for cessation of degranulation.     

Should human chondrocytes fly? The impact of electromagnetic irradiation on chondrocyte viability and implications for their use in tissue engineering

A significant logistic factor as to the successful clinical application of the autologous tissue engineering concept is efficient transportation: the donor cells need to be delivered to tissue processing facilities which in most cases requires air transportation. This study was designed to evaluate how human chondrocytes react to X-ray exposure. Primary cell cultures were established, cultured, incubated and exposed to different doses and time periods of radiation. Subsequently, quantitative cell proliferation assays were done and qualitative evaluation of cellular protein production were performed. Our results show that after irradiation of chondrocytes with different doses, no significant differences in terms of cellular viability occurred compared with the control group. These results were obtained when chondrocytes were exposed to luggage transillumination doses as well as exposure to clinically used radiation doses. Any damage affecting cell growth or quality was not observed in our study. However, information about damage of cellular DNA remains incomplete.     

Comparative analysis of the chemical treatments used in keratin extraction from red sheep’s hair and the cell viability evaluations of this keratin for tissue engineering applications

Hair waste is one of the solid substances rejected by the leather industry. This waste finds its way into the surroundings causing serious environmental pollution. This hair waste may be utilized for effective extraction of keratin, thereby generating value-added products with numerous applications. Thus we focusing on utilizing red sheep’s hair waste for extracting keratin by the application of different chemical treatments such as sodium hydroxide, sodium sulfide, mercaptoethanol, cysteine, sodium metabisulfite with urea (SMB), and SMB with SDS (SMBS). CD spectrum and FTIR results of the keratin samples indicated a predominance of the helical conformation along with β sheets. SDS-PAGE confirmed the molecular weight of the keratin samples to be in the range of 40–60 kDa. DSC and TGA analysis exhibited the extracted keratin to have a higher denaturation temperature (>200 °C) and thermal stability. The keratin samples obtained using varied chemical treatments were compared in terms of yield, protein content, and cost-effectiveness, and the sample obtained using SMBS was preferred for in vitro studies. It is indicated that keratin extracted using SMBS effectively involved for fibroblast cell growth. Thus, we suggest that these keratin could produce biomaterials that can serve as a valuable material for biomedical applications.     

In vitro drug release behavior from a novel thermosensitive composite hydrogel based on Pluronic f127 and poly(ethylene glycol)-poly(ε-caprolactone)-poly(ethylene glycol) copolymer

Background  

Most conventional methods for delivering chemotherapeutic agents fail to achieve therapeutic concentrations of drugs, despite reaching toxic systemic levels. Novel controlled drug delivery systems are designed to deliver drugs at predetermined rates for predefined periods at the target organ and overcome the shortcomings of conventional drug formulations therefore could diminish the side effects and improve the life quality of the patients. Thus, a suitable controlled drug delivery system is extremely important for chemotherapy.     

Supplementation of watermelon peels as an enhancer of lipase and esterase production by Yarrowia lipolytica in solid-state fermentation and their potential use as biocatalysts in poly(ethylene terephthalate) (PET) depolymerization reactions

Abstract

Yarrowia lipolytica is a yeast that presents high biotechnological potential due to its ability to produce many metabolites, among them lipases and esterases, which are important industrial biocatalysts. Since Brazil is an agroindustrial country, it generates an enormous diversity of residues or byproducts that can be used as a platform for biomolecules production. This work aims to evaluate lipase and esterase production by Y. lipolytica via solid-state fermentation using soybean bran and soybean bran supplemented with watermelon peels in different contents, and subsequent use of the enzyme extracts for poly(ethylene terephthalate) (PET) hydrolysis. Supplementation of watermelon peels in the lowest content led to an improvement of lipase activity in almost 31%, reaching 75.22?U g^?1. Esterase productivity was 1.5-fold higher when 20?wt% of watermelon peels were added to the media culture. Timecourse evaluation of enzymes production showed a maximum lipase activity in 14?h and similar esterase activity in 14 and 20?h of fermentation. Proteases production were also intensified in supplemented samples. Enzymes produced with 5?wt% watermelon peels supplementation led to higher terephthalic acid concentration (up to 42.02?µmol L^?1) during PET depolymerization. Results suggest a great potential of enzyme production in low cost fermentative media to act as biocatalysts in PET hydrolysis reactions.