Electrospun Structures Made of a Hydrolyzed Keratin-Based Biomaterial for Development of in vitro Tissue Models

Electrospun Poly-ε-Caprolactone Nanofibers Incorporating Keratin Hydrolysates as Innovative Antioxidant Scaffolds

This manuscript describes the development and characterization of electrospun nanofibers incorporating bioactive hydrolysates obtained from the microbial bioconversion of feathers, a highly available agro-industrial byproduct. The electrospun nanofibers were characterized using different instrumental methods, and their antioxidant properties and toxicological potential were evaluated. Keratin hydrolysates (KHs) produced by Bacillus velezensis P45 were incorporated at 1, 2.5, and 5% (w/w) into poly-ε-caprolactone (PCL; 10 and 15%, w/v solutions) before electrospinning. The obtained nanofibers were between 296 and 363 nm in diameter, showing a string-like morphology and adequate structural continuity. Thermogravimetric analysis showed three weight loss events, with 5% of the mass lost up to 330 °C and 90% from 350 to 450 °C. Infrared spectroscopy showed typical peaks of PCL and amide bands corresponding to keratin peptides. The biological activity was preserved after electrospinning and the hemolytic activity was below 1% as expected for biocompatible materials. In addition, the antioxidant capacity released from the nanofibers was confirmed by DPPH and ABTS radical scavenging activities. The DPPH scavenging activity observed for the nanofibers was greater than 30% after 24 h of incubation, ranging from 845 to 1080 µM TEAC (Trolox equivalent antioxidant capacity). The antioxidant activity for the ABTS radical assay was 44.19, 49.61, and 56.21% (corresponding to 972.0, 1153.3, and 1228.7 µM TEAC) for nanofibers made using 15% PCL with 1, 2.5, and 5% KH, respectively. These nanostructures may represent interesting antioxidant biocompatible materials for various pharmaceutical applications, including wound dressings, topical drug delivery, cosmetics, and packaging.

Keratose Self-Cross-Linked Wound Dressing for Iron Sequestration in Chronic Wounds

Chronic wound diseases affect a large part of the world population, and therefore, novel treatments are becoming fundamental. People with chronic wounds show high iron and protease levels due to genetic disorders or other comorbidities. Since it was demonstrated that iron plays an important role in chronic wounds, being responsible for oxidative processes (ROS generation), while metalloproteinases prevent wound healing by literally "eating" the growing skin, it is crucial to design an appropriate wound dressing. In this paper, a novel bioactive dressing for binding iron in chronic wounds has been produced. Wool-derived keratose wound dressing in the form of films has been prepared by casting an aqueous solution of keratoses. These films are water-soluble; therefore, in order to increase their stability, they have been made insoluble through a thermal cross-link treatment. Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA) analyses clarified the structure and the properties of the keratose wound dressing films. The capability of this new biomaterial in iron sequestration has been investigated by testing the adsorption of Fe3+ by inductively coupled plasma-optical emission spectrometry (ICP-OES). The results suggest that the keratose cross-linked films can adsorb a large amount of iron (about 85% of the average amount usually present in chronic wounds) following pseudo-second-order kinetics and an intraparticle diffusion model, thus opening new perspectives in chronic wound care. Furthermore, the QSAR Toolbox was applied for conducting in silico tests and for predicting the chemical behavior of the C-Ker-film. All of the data suggest that the keratose bioactive dressing can significantly contribute to wound healing by mechanisms such as iron depletion, acting as a radical scavenger, diminishing the proteolytic damage, acting as a substrate in place of skin, and, finally, promoting tissue regeneration.

Recent advances in electrospun protein fibers/nanofibers for the food and biomedical applications

Electrospinning (ES) is one of the most investigated processes for the convenient, adaptive, and scalable manufacturing of nano/micro/macro-fibers. With this technique, virgin and composite fibers may be made in different designs using a wide range of polymers (both natural and synthetic). Electrospun protein fibers (EPF) shave desirable capabilities such as biocompatibility, low toxicity, degradability, and solvolysis. However, issues with the proteins' processibility have limited their widespread utilization. This paper gives an overview of the features of protein-based biomaterials, which are already being employed and has the potential to be exploited for ES. State-of-the-art examples showcasing the usefulness of EPFs in the food and biomedical industries, including tissue engineering, wound dressings, and drug delivery, provided in the applications. The EPFs' future perspective and the challenge they pose are presented at the end. It is believed that protein and biopolymeric nanofibers will soon be manufactured on an industrial scale owing to the limitations of employing synthetic materials, as well as enormous potential of nanofibers in other fields, such as active food packaging, regenerative medicine, drug delivery, cosmetic, and filtration.

Wool Keratin Nanofibers for Bioinspired and Sustainable Use in Biomedical Field

Keratin is a biocompatible and biodegradable protein as the main component of wool and animal hair fibers. Keratin-based materials support fibroblasts and osteoblasts growth. Keratin has been extracted by sulphitolysis, a green method (no harmful chemicals) with a yield of 38-45%. Keratin has been processed into nanofibers from its solutions by electrospinning. Electrospinning is a versatile and easy-to-use technique to generate nanofibers. It is an eco-friendly and economical method for the production of randomly and uniaxially oriented polymeric nanofibers. Thanks to their high specific surface area, nanofibers have great potential in the biomedical field. Keratin nanofibers have received significant attention in biomedical applications, such as tissue engineering and cell growth scaffolds, for their biocompatibility and bio-functionality. Accordingly, we propose an extensive overview of recent studies focused on the optimization of keratinbased nanofibers, emphasizing their peculiar functions for cell interactions and the role of additive phases in blends or composite systems to particularize them as a function of specific applications (i.e., antibacterial).

Cross-Linked Gamma Polyglutamic Acid/Human Hair Keratin Electrospun Nanofibrous Scaffolds with Excellent Biocompatibility and Biodegradability

Recently, human hair keratin has been widely studied and applied in clinical fields due to its good histocompatibility, biocompatibility, and biodegradability. However, the regenerated keratin from human hair cannot be electrospun alone because of its low molecular weight. Herein, gamma polyglutamic acid (γ-PGA) was first selected to fabricate smooth and uniform γ-PGA/keratin composite scaffolds with excellent biocompatibility and biodegradability by electrospinning technology and a chemical cross-linking method in this study. The effect of electrospinning parameters on the structure and morphology, the mechanism of chemical cross-linking, biocompatibility in vitro cell culture experiments, and biodegradability in phosphate-buffered saline buffer solution and trypsin solution of the γ-PGA/keratin electrospun nanofibrous scaffolds (ENS) was studied. The results show that the cross-linked γ-PGA/keratin ENSs had excellent water stability and biodegradability. The γ-PGA/keratin ENSs showed better biocompatibility in promoting cell adhesion and cell growth compared with the γ-PGA ENSs. It is expected that γ-PGA/keratin ENSs will be easily and significantly used in tissue engineering to repair or regenerate materials.

One-Pot Process: Microwave-Assisted Keratin Extraction and Direct Electrospinning to Obtain Keratin-Based Bioplastic

Poultry feathers are among the most abundant and polluting keratin-rich waste biomasses. In this work, we developed a one-pot microwave-assisted process for eco-friendly keratin extraction from poultry feathers followed by a direct electrospinning (ES) of the raw extract, without further purification, to obtain keratin-based bioplastics. This microwave-assisted keratin extraction (MAE) was conducted in acetic acid 70% v/v. The effects of extraction time, solvent/feathers ratio, and heating mode (MAE vs. conventional heating) on the extraction yield were investigated. The highest keratin yield (26 ± 1% w/w with respect to initial feathers) was obtained after 5 h of MAE. Waste-derived keratin were blended with gelatin to fabricate keratin-based biodegradable and biocompatible bioplastics via ES, using 3-(Glycidyloxypropyl)trimethoxysilane (GPTMS) as a cross-linking agent. A full characterization of their thermal, mechanical, and barrier properties was performed by differential scanning calorimetry, thermogravimetric analysis, uniaxial tensile tests, and water permeability measurements. Their morphology and protein structure were investigated using scanning electron microscopy and attenuated total reflection-infrared spectroscopy. All these characterizations highlighted that the properties of the keratin-based bioplastics can be modulated by changing keratin and GPTMS concentrations. These bioplastics could be applied in areas such as bio-packaging and filtration/purification membranes.

Advances in the Development of Biomaterials for Endotoxin Adsorption in Sepsis

Sepsis, a life-threatening and intractable disease without any specific treatment, is activated by endotoxin. Some attempts at removing endotoxin to treat sepsis from the blood circulation using different hemoperfusion cartridges have been proposed recently, but they have failed to reduce the mortality of severe septic patients. This review summarizes the latest advances in the development of endotoxin adsorbents. In particular, we highlight two critical parameters for endotoxin adsorbents when they are applied in blood purification: the dissociation constant and the maximum adsorption capacity. We also discuss potential challenges and research directions for the future development of endotoxin adsorbents.

Physicochemical Characterization of Pectin-Gelatin Biomaterial Formulations for 3D Bioprinting

Developing biomaterial formulations with specific biochemical characteristics and physical properties suitable for bioprinting of 3D scaffolds is a pivotal challenge in tissue engineering. Therefore, the design of novel bioprintable formulations is a continuously evolving research field. In this work, the authors aim at expanding the library of biomaterial inks by blending two natural biopolymers: pectin and gelatin. Cytocompatible formulations are obtained by combining pectin and gelatin at different ratios and using (3-glycidyloxypropyl)trimethoxysilane (GPTMS) as single crosslinking agent. It is shown that the developed formulations are all suitable for extrusion-based 3D bioprinting. Self-supporting scaffolds with a designed macroporosity and micropores in the bioprinted struts are successfully obtained by combining extrusion-based bioprinting and freeze-drying. The presence of gelatin in these formulations allows for the modulation of porosity, of water uptake and of scaffold stiffness in respect to pure pectin scaffolds. Results demonstrate that these new biomaterial formulations, processed with this specific approach, are promising candidates for the fabrication of tissue-like scaffolds for tissue regeneration.

S100A4 Silencing Facilitates Corneal Wound Healing After Alkali Burns by Promoting Autophagy via Blocking the PI3K/Akt/mTOR Signaling Pathway

Purpose

This study investigated the role of S100 calcium binding protein A4 (S100A4) in corneal wound healing and the underlying mechanism of the S100A4-mediated PI3K/Akt/mammalian target of rapamycin (mTOR) pathway.

Methods

The rabbit corneal alkali burn model was established in vivo. S100A4 expression, wound healing, inflammation, and autophagy in rabbit cornea after alkali burn were detected. The NaOH-treated rabbit corneal stromal cells (rCSCs) were transfected with overexpressed S100A4 or silencing S100A4 to examine the effect of S100A4 on corneal wound healing in vitro. The effect of S100A4 on cell viability, proliferation, migration, invasion, fibrosis, and autophagy of rCSCs after alkali burn was analyzed. Then the functional rescue experiments were carried out. The PI3K inhibitor, LY294002, was used to elucidate the PI3K/Akt/mTOR signaling pathway in rCSCs.

Results

S100A4 silencing promoted rabbit corneal wound healing by inhibiting fibrosis and inflammation and promoting autophagy in alkali-burned cornea, corresponding to increased levels of LC3, Beclin 1, and Atg4B but lowered α-smooth muscle actin, TNF-ɑ, and p62 levels. Moreover, silencing S100A4 inhibited proliferation, migration, invasion, and fibrosis of NaOH-treated rCSCs and promoted the differentiation of rCSCs into corneal cells and the autophagy of damaged rCSCs. The inhibitory role of S100A4 in wound healing was achieved via activation of the PI3K/Akt/mTOR pathway.

Conclusions

S100A4 silencing confers a promising effect on wound healing of alkali-burned cornea by blocking the PI3K/Akt/mTOR pathway, supporting the advancement of corneal gene therapies for wound healing.

Long non-coding RNA SNHG3 promotes breast cancer cell proliferation and metastasis by binding to microRNA-154-3p and activating the notch signaling pathway

BACKGROUND

Breast cancer (BC) is a malignant tumor that occurs in the epithelial tissue of the breast gland. Long non-coding RNA (lncRNA) small nucleolar RNA host gene 3 (SNHG3) has been found to promote BC cell proliferation and invasion by regulating the microRNA (miR)-101/zinc-finger enhancer binding axis in BC. Herein, the objective of the present study is to evaluate the effect of lncRNA SNHG3 on BC cell proliferation and metastasis with the Notch signaling pathway.

METHODS

Differentially expressed lncRNA in BC tissues and normal breast tissues was analyzed. SNHG3 si-RNA-1 and SNHG3 si-RNA-2 were constructed to detect the mechanism of SNHG3 interference in BC cell proliferation, viability, migration and invasion. Then, dual-luciferase reporter gene assay was utilized to verify the binding relation between SNHG3 and miR-154-3p as well as miR-154-3p and Notch2. Moreover, xenograft transplantation was applied to confirm the in vitro experiments.

RESULTS

Highly expressed SNHG3 was observed in BC tissues. The growth of BC cells in vivo and in vitro was evidently repressed after silencing SNHG3. BC cell invasion and migration were inhibited by silencing SNHG3 in vitro. SNHG3 could act as a competing endogenous RNA of miR-154-3p and upregulate the Notch signaling pathway to promote BC cell development. Activation of the Notch signaling pathway can partly reverse the inhibition of cell activity induced by silencing SNHG3.

CONCLUSION

Our study demonstrated that interfered lncRNA SNHG3 promoted BC cell proliferation and metastasis by activating the Notch signaling pathway. This investigation may offer new insight for BC treatment.

Keratin - Based materials for biomedical applications

Keratin constitutes the major component of the feather, hair, hooves, horns, and wool represents a group of biological material having high cysteine content (7-13%) as compared to other structural proteins. Keratin -based biomaterials have been investigated extensively over the past few decades due to their intrinsic biological properties and excellent biocompatibility. Unlike other natural polymers such as starch, collagen, chitosan, the complex three-dimensional structure of keratin requires the use of harsh chemical conditions for their dissolution and extraction. The most commonly used methods for keratin extraction are oxidation, reduction, steam explosion, microbial method, microwave irradiation and use of ionic liquids. Keratin -based materials have been used extensively for various biomedical applications such as drug delivery, wound healing, tissue engineering. This review covers the structure, properties, history of keratin research, methods of extraction and some recent advancements related to the use of keratin derived biomaterials in the form of a 3-D scaffold, films, fibers, and hydrogels.

MicroRNA-10a promotes epithelial-to-mesenchymal transition and stemness maintenance of pancreatic cancer stem cells via upregulating the Hippo signaling pathway through WWC2 inhibition

MicroRNAs (miRNAs)-mediated cancer stem cells (CSCs) have drawn wide attention. This study aimed to probe the role of miR-10a in epithelial-mesenchymal transition (EMT) and stemness maintenance of pancreatic CSCs (PCSCs). Differentially expressed miRs and genes in pancreatic cancer (PC) were predicted via an online database, and the miR-10a and WW and C2 domain containing 2 (WWC2) expression were identified via a comparative study in PC and pancreatitis tissues. PCNCs were isolated and identified, and then the functional roles of miR-10a and WWC2 in proliferation, invasion, migration, self-renewal, colony formation abilities, EMT, and stemness maintenance of PCNCs were determined. The effects of miR-10a on tumor growth in vivo were studied by performing a xenograft tumor in nude mice. Consequently, miR-10a was highly expressed while WWC2 was lowly expressed in PC tissues. miR-10a could target WWC2 expression. miR-10a inhibition reduced EMT and stemness maintenance of PCSCs via enhancing WWC2 expression. The in vitro results were reproduced in in vivo studies. miR-10a promoted EMT and stemness maintenance of PCSCs via activating the Hippo signaling pathway. Our study provided evidence that miR-10a inhibition reduced EMT and stemness maintenance of PCSCs via upregulating WWC2 expression and inhibiting the Hippo signaling pathway.