Hyaluronic Acid Hydrogel Containing Resveratrol-Loaded Chitosan Nanoparticles as an Adjuvant in Atopic Dermatitis Treatment.

Atopic dermatitis (AD) is a common disease-causing skin inflammation, redness, and irritation, which can eventually result in infection that drastically impacts patient quality of life. Resveratrol (Res) is a natural phytochemical famed for its excellent anti-inflammatory and antioxidant activities. However, it is poorly bioavailable. Thus, a drug delivery system is needed to enhance in vivo bioactivity. Herein, we report the preparation of hyaluronic acid (HA) hydrogels containing resveratrol-loaded chitosan (CS) nanoparticles, their physicochemical analysis, and their potential therapeutic effects in the treatment of AD. Positively charged CS nanoparticles prepared by tripolyphosphate (TPP) gelation showed sizes ranging from 120 to around 500 nm and Res encapsulation efficiency as high as 80%. Embedding the nanoparticles in HA retarded their hydrolytic degradation and also slowed resveratrol release. Resveratrol released from nanoparticle-loaded hydrogel counteracted the oxidative damage induced by ROS generation in TNF-α/INF-γ-treated human keratinocytes (HaCaT) used as an AD in vitro model. Moreover, pre-treatment with Res@gel reduced secretion and gene expression of proinflammatory cytokines in HaCaT cells. The physicochemical analysis and in vitro assay confirmed that the formulated hydrogel could be considered an efficient and sustained resveratrol delivery vector in AD treatment.

Spatial patterning of PCLµ-scaffolds directs 3D vascularized bio-constructs morphogenesisin vitro.

Modular tissue engineering (mTE) strategies aim to build three-dimensional tissue analoguesin vitroby the sapient combination of cells, micro-scaffolds (µ-scaffs) and bioreactors. The translation of these newly engineered tissues into current clinical approaches is, among other things, dependent on implant-to-host microvasculature integration, a critical issue for cells and tissue survivalin vivo. In this work we reported, for the first time, a computer-aided modular approach suitable to build fully vascularized hybrid (biological/synthetic) constructs (bio-constructs) with micro-metric size scale control of blood vessels growth and orientation. The approach consists of four main steps, starting with the fabrication of polycaprolactoneµ-scaffs by fluidic emulsion technique, which exhibit biomimetic porosity features. In the second step, layers ofµ-scaffs following two different patterns, namely ordered and disordered, were obtained by a soft lithography-based process. Then, the as obtainedµ-scaff patterns were used as template for human dermal fibroblasts and human umbilical vein endothelial cells co-culture, aiming to promote and guide the biosynthesis of collagenous extracellular matrix and the growth of new blood vessels within the mono-layered bio-constructs. Finally, bi-layered bio-constructs were built by the alignment, stacking and fusion of two vascularized mono-layered samples featuring ordered patterns. Our results demonstrated that, if compared to the disordered pattern, the ordered one provided better control over bio-constructs shape and vasculature architecture, while minor effect was observed with respect to cell colonization and new tissue growth. Furthermore, by assembling two mono-layered bio-constructs it was possible to build 1 mm thick fully vascularized viable bio-constructs and to study tissue morphogenesis during 1 week ofin vitroculture. In conclusion, our results highlighted the synergic role ofµ-scaff architectural features and spatial patterning on cells colonization and biosynthesis, and pave the way for the possibility to create in silico designed vasculatures within modularly engineered bio-constructs.

Edible Polymers and Secondary Bioactive Compounds for Food Packaging Applications: Antimicrobial, Mechanical, and Gas Barrier Properties.

Edible polymers such as polysaccharides, proteins, and lipids are biodegradable and biocompatible materials applied as a thin layer to the surface of food or inside the package. They enhance food quality by prolonging its shelf-life and avoiding the deterioration phenomena caused by oxidation, humidity, and microbial activity. In order to improve the biopolymer performance, antimicrobial agents and plasticizers are also included in the formulation of the main compounds utilized for edible coating packages. Secondary natural compounds (SC) are molecules not essential for growth produced by some plants, fungi, and microorganisms. SC derived from plants and fungi have attracted much attention in the food packaging industry because of their natural antimicrobial and antioxidant activities and their effect on the biofilm's mechanical properties. The antimicrobial and antioxidant activities inhibit pathogenic microorganism growth and protect food from oxidation. Furthermore, based on the biopolymer and SC used in the formulation, their specific mass ratio, the peculiar physical interaction occurring between their functional groups, and the experimental procedure adopted for edible coating preparation, the final properties as mechanical resistance and gas barrier properties can be opportunely modulated. This review summarizes the investigations on the antimicrobial, mechanical, and barrier properties of the secondary natural compounds employed in edible biopolymer-based systems used for food packaging materials.

Bioinspired Design of Novel Microscaffolds for Fibroblast Guidance toward In Vitro Tissue Building.

Porous microscaffolds (µ-scaffs) play a crucial role in modular tissue engineering as they control cell functions and guide hierarchical tissue formation toward building new functional tissue analogues. In the present study, we developed a new route to prepare porous polycaprolactone (PCL) µ-scaffs with a bioinspired trabecular structure that supported in vitro adhesion, growth, and biosynthesis of human dermal fibroblasts (HDFs). The method involved the use of poly(ethylene oxide) (PEO) as a biocompatible porogen and a fluidic emulsion/porogen leaching/particle coagulation process to obtain spherical µ-scaffs with controllable diameter and full pore interconnectivity. To achieve this objective, we investigated the effect of PEO concentration and the temperature of the coagulation bath on the µ-scaff architecture, while we modulated the µ-scaff diameter distribution by varying the PCL-PEO amount in the starting solution and changing the flow rate of the continuous phase (QCP). µ-Scaff morphology, pore architecture, and diameter distribution were assessed using scanning electron microscopy (SEM) analysis, microcomputed tomography (microCT), and Image analysis. We reported that the selection of 60 wt % PEO concentration, together with a 4 °C coagulation bath temperature and ultrasound postprocessing, allowed for the design and fabrication of µ-scaff with porosity up to 80% and fully interconnected pores on both the µ-scaff surface and the core. Furthermore, µ-scaff diameter distributions were finely tuned in the 100-600 µm range with the coefficient of variation lower than 5% by selecting the PCL-PEO concentration in the 1-10% w/v range and QCP of either 8 or 18 mL/min. Finally, we investigated the capability of the HDF-seeded PCL µ-scaff to form hybrid (biological/synthetic) tissue in vitro. Cell culture tests demonstrated that PCL µ-scaff enabled HDF adhesion, proliferation, colonization, and collagen biosynthesis within inter- and intraparticle spaces and guided the formation of a large (centimeter-sized) viable tissue construct.

Tuning the three-dimensional architecture of supercritical CO2 foamed PCL scaffolds by a novel mould patterning approach.

In tissue engineering, the use of supercritical CO2 foaming is a valuable and widespread choice to design and fabricate porous bioactive scaffolds for cells culture and new tissue formation in three dimensions. Nevertheless, the control of scaffold pores size, shape and spatial distribution with foaming technique remains, to date, a critical limiting step. To mimic the biomimetic structure of tissues like bone, blood vessels and nerve tissues, we developed a novel supercritical CO2-foaming approach for the preparation of dual-scale, dual-shape porous polymeric scaffolds with pre-defined arrays of micro-channels within a foamed porosity. The scaffolds were prepared by foaming the polymer inside polytetrafluoroethylene moulds having precisely designed arrays of pillars and obtained by computer-aided micromachining technique. Polycaprolactone was chosen as model polymer for scaffolds fabrication and the effect of mould patterning and scCO2 foaming conditions on scaffolds morphology, structural properties and biocompatibility was addressed and discussed. The results reported in this study demonstrated that the proposed approach enabled the preparation of polycaprolactone scaffolds with dual-scale, dual-shape porosity. In particular, by saturating the polymer with CO2 at 38 °C, 10 MPa and 1 h and by selecting 2 s as the venting time, scaffolds with ordered arrays of aligned channels, diameters ranging from 500 to 1000 µm, were obtained. Furthermore, the channels spatial distribution was controlled by defining mould patterning while the size of foamed pores was modulated by saturation and foaming temperatures and venting time control. The prepared scaffolds evidenced overall porosity up to 95%, with 100% interconnectivity and compression moduli in the 4 to 5 MPa range. Finally, preliminary in vitro cell culture tests evidenced that the scaffolds were biocompatible and that the micro-channels promoted and guided cells adhesion and colonization into the scaffolds core.

Wound healing and antimicrobial effect of active secondary metabolites in chitosan-based wound dressings: A review.

Wound healing can lead to complex clinical problems, hence finding an efficient approach to enhance the healing process is necessary. An ideal wound dressing should treat wounds at reasonable costs, with minimal inconveniences for the patient. Chitosan is one of the most investigated biopolymers for wound healing applications due to its biocompatibility, biodegradability, non-toxicity, and antimicrobial activity. Moreover, chitosan and its derivative have attracted numerous attentions because of the accelerating wound healing, and easy processability into different forms (gels, foams, membranes, and beads). All these properties make chitosan-based materials particularly versatile and promising for wound dressings. Besides, secondary natural metabolites could potentially act like the antimicrobial and anti-inflammatory agents and accelerate the healing process. This review collected almost all studies regarding natural compounds applications in wound healing by focusing on the chitosan-based bioactive wound dressing systems. An accurate analysis of different chitosan formulations and the influence of bioactive compounds on their wound healing properties are reported.

Modular Strategies to Build Cell-Free and Cell-Laden Scaffolds towards Bioengineered Tissues and Organs.

Engineering three-dimensional (3D) scaffolds for functional tissue and organ regeneration is a major challenge of the tissue engineering (TE) community. Great progress has been made in developing scaffolds to support cells in 3D, and to date, several implantable scaffolds are available for treating damaged and dysfunctional tissues, such as bone, osteochondral, cardiac and nerve. However, recapitulating the complex extracellular matrix (ECM) functions of native tissues is far from being achieved in synthetic scaffolds. Modular TE is an intriguing approach that aims to design and fabricate ECM-mimicking scaffolds by the bottom-up assembly of building blocks with specific composition, morphology and structural properties. This review provides an overview of the main strategies to build synthetic TE scaffolds through bioactive modules assembly and classifies them into two distinct schemes based on microparticles (µPs) or patterned layers. The µPs-based processes section starts describing novel techniques for creating polymeric µPs with desired composition, morphology, size and shape. Later, the discussion focuses on µPs-based scaffolds design principles and processes. In particular, starting from random µPs assembly, we will move to advanced µPs structuring processes, focusing our attention on technological and engineering aspects related to cell-free and cell-laden strategies. The second part of this review article illustrates layer-by-layer modular scaffolds fabrication based on discontinuous, where layers' fabrication and assembly are split, and continuous processes.