Incorporation of the Tat cell‐penetrating peptide into nanofibers improves the respective antitumor immune response

A major challenge for the development of anticancer vaccines is the induction of a safe and effective immune response, particularly mediated by CD8+ T lymphocytes, in an adjuvant‐free manner. In this respect, we present a simple strategy to improve the specific CD8+ T cell responses using KFE8 nanofibers bearing a Class I (Kb)‐restricted peptide epitope (called E. nanofibers) without the use of adjuvant. We demonstrate that incorporation of Tat, a cell‐penetrating peptide (CPP) of the HIV transactivator protein, into E. nanofibers remarkably enhanced tumor‐specific CD8+ T cell responses. E. nanofibers containing 12.5% Tat peptide (E.Tat_12.5 nanofiber) increased antigen cross‐presentation by bone marrow‐derived dendritic cells as compared with E. nanofibers, or E. nanofibers containing 25 or 50% the Tat peptide. Uptake of KFE8.Tat_12.5 nanofibers by dendritic cells (DCs) was significantly increased compared with KFE8 nanofiber lacking Tat. Peritoneal and lymph node DCs of mice immunized with E.Tat_12.5 nanofibers exhibited increased presentation of the H2kb‐epitope (reminiscent for cross‐presentation) compared with DCs obtained from E. nanofiber vaccinated mice. Tetrameric and intracellular cytokine staining revealed that vaccination with E.Tat_12.5 triggered a robust and specific CD8+ T lymphocyte response, which was more pronounced than in mice vaccinated with E. nanofibers alone. Furthermore, E.Tat_12.5 nanofibers were more potent than E. nanofiber to induce antitumor immune response and tumor‐infiltrating IFN‐γ CD8 T lymphocyte. In terms of cancer vaccine development, we propose that harnessing the nanofiber‐based vaccine platform with incorporated Tat peptide could present a simple and promising strategy to induce highly effective antitumor immune response.     

Production of collagen micro- and nanofibers for potential drug-carrier systems

Abstract

Two different nano- and micro-collagen fiber production methods are introduced and discussed. First one is the electrospinning method, that is very common technique to produce nanofibers from different polymeric solutions and recently collagen solutions are employed to produce nanofibers for different biomedical applications. This technique is extremely versatile method to produce nanofibers in a relatively short time, easy to control the fiber diameter and orientation with small pore sizes and a high surface area. The second method is self-assembly of collagen micro-fibers by co-extrusion method. The collagen fibers are obtained without any cross-linker, by using mainly ionic interactions. We demonstrated that self-assembled collagen fibers have well preserved their native structure (0.90 PP-II fraction), when compared with electrospun collagen fibers (0.38 PP-II fraction). However, it was only possible to produce collagen fibers with nanodimensions by using electrospinning method.     

Immobilization of laccase onto modified PU/RC nanofiber via atom transfer radical polymerization method and application in removal of bisphenol A

In this study, 2‐hydroxyethyl methacrylate (HEMA) was used as the monomers for surface grafting on electrospun PU/RC nanofiber membrane via atom transfer radical polymerization (ATRP) method, and the PU/RC‐poly(HEMA) nanofiber membrane was investigated as a carrier for LAC. Free and immobilized LAC was characterized, and efficiency of bisphenol A (BPA) removal was determined. The results indicated that the PU/RC‐poly(HEMA)‐LAC showed relatively higher pH stability, temperature stability, and storage stability than free and PU/RC‐LAC; moreover, more than 60% of the PU/RC‐poly(HEMA)‐LAC activity was retained after 10 cycles of ABTS treatment. Notably, the BPA removal efficiency of PU/RC‐poly(HEMA)‐LAC membrane generally ranged from 87.3 to 75.4% for the five cycles. Therefore, the PU/RC‐poly(HEMA) nanofiber membrane has great potential as a carrier for the LAC immobilization for various industrial applications and bioremediation.     

Curcumin nanofibers for the purpose of wound healing

Poor wound healing is a highly prevalent clinical problem with, as yet, no entirely satisfactory solution. A new technique, termed electrospinning, may provide a solution to improve wound healing. Due to their large surface area to volume ratio and porosity, the nanofibers created by electrospinning are able to deliver sustained drug release and oxygen to the wound. Using different types of polymers with varying properties helps strengthening nanofiber and exudates absorption. The nanofibers appear to have an ideal structure applicable for wound healing and, in combination with curcumin, can blend the anti-inflammatory and antioxidant properties of curcumin into a highly effective wound dressing. The use of suitable curcumin solvents and the slow release of curcumin from the nanofiber help in overcoming the known limitations of curcumin, specifically its low stability and limited bioavailability. Here, we review the studies which have been done on synthesized nanofibers containing curcumin, produced by the electrospinning technique, for the purpose of wound healing.     

A combination of bioactive and nonbioactive alkyl-peptides form a more stable nanofiber structure for differentiating neural stem cells: a molecular dynamics simulation survey

Self-assembling alkyl-peptides are important molecules due to their ability to construct nano-level structures such as nanofibers to be utilized as tissue engineering scaffolds. The bioactive epitope of FAQRVPP which acts as neural stem cells (NSCs) outgrowth inducing factor is used in nanofiber structures. Based on previous experimental studies the density and distribution pattern of the epitopes on the surface of the nanofibers plays an important role in the differentiation function efficiency. We decided to survey and compare the stability of two pre-constructed fiber structures in the forms of all-functionalized nanofiber (containing only bioactive alkyl-peptides) and distributed functionalized nanofiber (a combination of nonbioactive and bioactive alkyl-peptides with ratio 2:1). Our findings reveal that the all-functionalized fiber shows an unstable structure and is split into intermediate micelle-like structures to reduce compactness and steric hindrance of functional epitopes whereas the distributed functionalized fiber shows an integrated stable nanofiber with a more amount of beta sheets that are well-organized and oriented around the hydrophobic core. The hydrogen bonds and energy profiles of the structures indicate the role of hydrophobic interactions during the alkyl-chain core formation and the important role of electrostatic interactions and hydrogen bond network in the stability of the final structures. Finally, it seems that the possibility of the presence of intermediate structure is increased in the all-functionalized nanofiber environment, and it can reduce functional efficiency of the scaffolds. These findings can help to design more efficient nanofiber structures with different goals in scaffolds for tissue engineering. Abbreviations MD Molecular Dynamics

NSCs Neural Stem Cells

PME Particle mesh Ewald

RDF Radial Distribution Function

RG Radius of gyration

RASA Relative Accessible Surface Area

RMSD Root Mean Square Deviations

SASA Solvent Accessible Surface Area.

Communicated by Ramaswamy H. Sarma     

Nanofibers and their applications in tissue engineering

Developing scaffolds that mimic the architecture of tissue at the nanoscale is one of the major challenges in the field of tissue engineering. The development of nanofibers has greatly enhanced the scope for fabricating scaffolds that can potentially meet this challenge. Currently, there are three techniques available for the synthesis of nanofibers: electrospinning, self-assembly, and phase separation. Of these techniques, electrospinning is the most widely studied technique and has also demonstrated the most promising results in terms of tissue engineering applications. The availability of a wide range of natural and synthetic biomaterials has broadened the scope for development of nanofibrous scaffolds, especially using the electrospinning technique. The three dimensional synthetic biodegradable scaffolds designed using nanofibers serve as an excellent framework for cell adhesion, proliferation, and differentiation. Therefore, nanofibers, irrespective of their method of synthesis, have been used as scaffolds for musculoskeletal tissue engineering (including bone, cartilage, ligament, and skeletal muscle), skin tissue engineering, vascular tissue engineering, neural tissue engineering, and as carriers for the controlled delivery of drugs, proteins, and DNA. This review summarizes the currently available techniques for nanofiber synthesis and discusses the use of nanofibers in tissue engineering and drug delivery applications.     

Fabrication of nanofiber coated with l-arginine via electrospinning technique: a novel nanomatrix to counter oxidative stress under crosstalk of co-cultured fibroblasts and satellite cells

The objective of this study was to synthesize and characterize novel polyurethane (PU)-nanofiber coated with l-arginine by electrospinning technique. This study determined whether l-arginine conjugated with PU-nanofiber could stimulate cell proliferation and prevent H₂O₂-induced cell death in satellite cells co-cultured with fibroblasts isolated from Hanwoo (Korean native cattle). Our results showed that l-arginine conjugated with PU nanofiber could reduce cytotoxicity of co-cultured satellite cells. Protein expression levels of bcl-2 were significantly upregulated whereas those of caspase-3 and caspase-7 were significantly downregulated in co-culture of satellite cells compared to those of monoculture cells after treatment with PU-nanofiber coated with l-arginine and which confirmed by Confocal microscope. These results suggest that co-culture of satellite cells with fibroblasts might be able to counter oxidative stress through translocation/penetration of antioxidant, collagen, and molecules secreted to satellite cells. Therefore, this nanofiber might be useful as a wound dressing in animals to counter oxidative stresses.     

自组装IKVAV多肽纳米纤维支架凝胶及其对嗅鞘细胞的作用

旨在观察自组装IKVAV多肽纳米纤维支架凝胶对鼠嗅鞘细胞(OECs)的作用。通过调整IKVAV溶液pH值并加入培养液触发多肽自组装为支架凝胶, 用原子力显微镜检测IKVAV分子可以自组装成编织状纳米纤维(直径为3~5 nm)。采用原代分离培养方法获得OECs单细胞悬液后, 使用差速贴壁法两次纯化OECs且在第12天通过免疫染色计数OECs纯度为85%。将IKVAV多肽纳米纤维支架凝胶与OECs复合培养, 倒置显微镜下观察OECs生长良好, Calcein-AM/PI活、死细胞染色表明活细胞数达95%。CCK-8法间接细胞计数证实IKVAV多肽可促进OECs的黏附, 对OECs增殖没有影响。由此可见IKVAV多肽可以自组装成纳米纤维支架凝胶且对OECs有良好的生物相容性及黏附作用, 可作为神经组织工程支架材料。