Advanced Polymeric Membranes as Biomaterials Based on Marine Sources Envisaging the Regeneration of Human Tissues

The self-repair capacity of human tissue is limited, motivating the arising of tissue engineering (TE) in building temporary scaffolds that envisage the regeneration of human tissues, including articular cartilage. However, despite the large number of preclinical data available, current therapies are not yet capable of fully restoring the entire healthy structure and function on this tissue when significantly damaged. For this reason, new biomaterial approaches are needed, and the present work proposes the development and characterization of innovative polymeric membranes formed by blending marine origin polymers, in a chemical free cross-linking approach, as biomaterials for tissue regeneration. The results confirmed the production of polyelectrolyte complexes molded as membranes, with structural stability resulting from natural intermolecular interactions between the marine biopolymers collagen, chitosan and fucoidan. Furthermore, the polymeric membranes presented adequate swelling ability without compromising cohesiveness (between 300 and 600%), appropriate surface properties, revealing mechanical properties similar to native articular cartilage. From the different formulations studied, the ones performing better were the ones produced with 3 % shark collagen, 3% chitosan and 10% fucoidan, as well as with 5% jellyfish collagen, 3% shark collagen, 3% chitosan and 10% fucoidan. Overall, the novel marine polymeric membranes demonstrated to have promising chemical, and physical properties for tissue engineering approaches, namely as thin biomaterial that can be applied over the damaged articular cartilage aiming its regeneration.

The biomimetic surface topography ofRubus fruticosusleaves stimulate the induction of osteogenic differentiation of rBMSCs

The interaction between cells and biomaterials is essential for the success of biomedical applications in which the implantation of biomaterials in the human body is necessary. It has been demonstrated that material´s chemical, mechanical, and structural properties can influence cell behavior. The surface topography of biomaterials is a physical property that can have a major role in mediating cell-material interactions. This interaction can lead to different cell responses regarding cell motility, proliferation, migration, and even differentiation. The combination of biomaterials with mesenchymal stem cells (MSCs) for bone regeneration is a promising strategy to avoid the need for autologous transplant of bone. Surface topography was also associated with the capacity to control MSCs differentiation. Most of the topographies studied so far involve machine-generated surface topographies. Herein, our strategy differentiates from the above mentioned since we selected natural surface topographies that can modulate cell functions for regenerative medicine strategies.
Rubus fruticosus leaf was the selected topography to be replicated in PCL membranes through Polydimethylsiloxane (PDMS) moulding and using soft lithography. Afterwards, rat bone marrow stem cells (rBMSC) were seeded at the surface of the imprinted PCL membranes to characterize the bioactive potential of our biomimetic surface topography to drive rBMSCs differentiation into the osteogenic lineage. The selected surface topography in combination with the osteogenic inductive medium reveals having a synergistic effect promoting osteogenic differentiation.

Microphysiological systems to study colorectal cancer: State-of-the-art

Colorectal cancer (CRC) still has a high prevalence of mortality in the world. So far, basic pre-clinical research based on 2D cultures has failed to improve patient prognostic outcomes. A growing field of research based on microphysiological systems (MPS) involvingorganoids/spheroids or patient-derived tumour cells has become a solid base for a better understanding of the tumour microenvironment and as a result a step towards personalized medicine. Furthermore, microfluidic approaches have also started to open possibilities of research, with tumour-on-chips and body-on-chips being used in order to decipher complex inter-organ signalling and the prevalence of metastasis, as well as CRC early-diagnosis through liquid biopsies. Herein, we focus on the state-of-the-art of CRC research with emphasis on 3D microfluidic in vitro cultures - organoids, spheroids - drug resistance, circulating tumour cells (CTCs) and microbiome-on-a-chip technology.&#xD.

On the size-dependent internalization of sub-hundred polymeric nanoparticles

The understanding of the interaction between nanoparticles (NPs) and cells is crucial to design nanocarriers with high therapeutic relevance. In this study, we exploited a microfluidics device to synthesize homogeneous suspensions of NPs with ≈ 30, 50, and 70 nm of size. Afterward, we investigated their level and mechanism of internalization when exposed to different types of cells (endothelial cells, macrophages, and fibroblasts). Our results show that all NPs were cytocompatible and internalized by the different cell types. However, NPs uptake was size-dependent, being the maximum uptake efficiency observed for the 30 nm NPs. Moreover, we demonstrate that size can lead to distinct interactions with different cells. For instance, 30 nm NPs were internalized with an increasing trend over time by endothelial cells, while a steady and a decreasing trend were observed when incubated with LPS-stimulated macrophages and fibroblasts, respectively. Finally, the use of different chemical inhibitors (chlorpromazine, cytochalasin-D, and nystatin), and low temperature (4 °C) indicated that phagocytosis/micropinocytosis are the main internalization mechanism for all NPs sizes. However, different endocytic pathways were initiated in the presence of particular NP sizes. In endothelial cells, for example, caveolin-mediated endocytosis occurs primarily in the presence of 50 nm NPs, whereas clathrin-mediated endocytosis substantially promotes the internalization of 70 nm NPs. This evidence demonstrates the importance of size in the NPs design for mediating interaction with specific cell types.

Menthol-based deep eutectic systems as antimicrobial and anti-inflammatory agents for wound healing

Effective antimicrobial treatment has been identified as a serious and unmet medical need. Herein, we present a strategy based on deep eutectic systems (DES) to overcome current limitations, answering the need not only to effectively kill bacterial agents but also to avoid their adhesion and proliferation, which is associated with biofilm formation and have a crucial impact on bacterial virulence. To achieve such a goal, natural deep eutectic systems (NADES) based on menthol (Me) and saturated free fatty acids (FFA) were produced, fully physicochemical characterized, and its bioactive properties were described. The antimicrobial potential of menthol-based NADES with FFA, namely, myristic acid (MA), lauric acid (LA), and stearic acid (SA) were investigated towards a broad panel of microorganisms. The obtained data indicates that NADES possess effective antimicrobial properties towards the Gram-positive bacterial and fungal strains tested. Among the tested formulations, Me:LA at a molar ratio of 4:1 molar was used to carry out a biofilm detachment/removal assay due to is superior microbiological properties. This formulation was able to effectively lead to biofilm removal/dispersion of not only methicillin-resistant Staphylococcus aureus (MRSA) and Candida albicans, but also Escherichia coli, without the need of any additional physical force or antibiotic. Furthermore, since microbial invasion and biofilm formation is highly undesired in wound healing, namely in chronic wound healing, the wound healing properties of these eutectic formulations was also investigated. The results suggest that these NADES can cope with microbial invasion and biofilm detachment while not compromising normal keratinocyte proliferation and migration verified in wound healing and epidermis repair, while also contributing to the reduction of cell stress and inflammation via the control of ROS production. In conclusion, these results provide the indication that NADES based on Me and FFA holds great interest as antimicrobial agents for preventive and therapeutic applications in various clinical settings, including wound healing.

Stromal Vascular Fraction Obtained From Subcutaneous Adipose Tissue: Ex-Obese and Older Population as Main Clinical Targets

INTRODUCTION

Human adipose tissue contains a heterogeneous and synergistic mixture of cells called stromal vascular fraction (SVF) with highly proliferative and angiogenic properties, conferring promising applicability in the field of regenerative medicine. This study aims to investigate if age, body mass index (BMI), history of obesity and massive weight loss, and harvest site are related to SVF cell marker expression.

METHODS

A total of 26 samples of subcutaneous adipose tissue were harvested from patients admitted to the Plastic and Reconstructive department in University Hospital Center of São João, Porto, Portugal, for body contouring surgery. The percentage of cells expressing CD31, CD34, CD45, CD73, CD90, and CD105 was assessed and compared with patient's age, BMI, history of obesity and massive weight loss (ex-obese group), and harvest site.

RESULTS

In the ex-obese group, a significantly higher number of cells expressing CD90 (P = 0.002) was found. BMI, harvest site, and age appear to have no association with SVF subpopulations.

CONCLUSIONS

This study suggests that ex-obese patients have a higher percentage of SVF cells expressing CD90, which correlates with higher proliferative and angiogenic rates. The effect of former obesity and massive weight loss on the expression of CD90 is a new and relevant finding because it makes this population a suitable candidate for reconstructive and aesthetic surgery and other fields of regenerative medicine. The use of SVF appears also promising in older patients because no negative correlation between increasing age and different cell markers expression was found.

Innovative Antibacterial, Photocatalytic, Titanium Dioxide Microstructured Surfaces Based on Bacterial Adhesion Enhancement

Bacterial colonization and biofilm formation are found on nearly all wet surfaces, representing a serious problem for both human healthcare and industrial applications, where traditional treatments may not be effective. Herein, we describe a synergistic approach for improving the performance of antibacterial surfaces based on microstructured surfaces that embed titanium dioxide nanoparticles (TiO₂ NPs). The surfaces were designed to enhance bacteria entrapment, facilitating their subsequent eradication by a combination of UVC disinfection and TiO₂ NPs photocatalysis. The efficacy of the engineered TiO₂-modified microtopographic surfaces was evaluated using three different designs, and it was found that S2-lozenge and S3-square patterns had a higher concentration of trapped bacteria, with increases of 70 and 76%, respectively, compared to flat surfaces. Importantly, these surfaces showed a significant reduction (99%) of viable bacteria after just 30 min of irradiation with UVC 254 nm light at low intensity, being sixfold more effective than flat surfaces. Overall, our results showed that the synergistic effect of combining microstructured capturing surfaces with the chemical functionality of TiO₂ NPs paves the way for developing innovative and efficient antibacterial surfaces with numerous potential applications in the healthcare and biotechnology market.

Hyaluronan Receptors as Mediators and Modulators of the Tumor Microenvironment

The tumor microenvironment (TME) is a dynamic and complex matter shaped by heterogenous cancer and cancer-associated cells present at the tumor site. Hyaluronan (HA) is a major TME component that plays pro-tumorigenic and carcinogenic functions. These functions are mediated by different hyaladherins expressed by cancer and tumor-associated cells triggering downstream signaling pathways that determine cell fate and contribute to TME progression toward a carcinogenic state. Here, the interaction of HA is reviewed with several cell-surface hyaladherins-CD44, RHAMM, TLR2 and 4, LYVE-1, HARE, and layilin. The signaling pathways activated by these interactions and the respective response of different cell populations within the TME, and the modulation of the TME, are discussed. Potential cancer therapies via targeting these interactions are also briefly discussed.

Collagen membrane from bovine pericardium for treatment of long bone defect

The treatment of bone regeneration failures has been constantly improved with the study of new biomaterials. Techgraft® is a collagen membrane derived from bovine pericardium, which has been shown to have biocompatibility and effectiveness in tissue repair. However, its use in orthopedics has not yet been evaluated. Therefore, the purpose of this study was to characterize a bovine pericardium collagen membrane and evaluate the effects of its use in the regeneration of a bone defect in rat tibia. Scanning electron microscopy, atomic force microscopy, weight lost and water uptake tests, and mechanical test were performed. Afterwards, the membrane was tested in an experimental study, using 12 male Sprague Dawley rats. A bone defect was surgically made in tibiae of animals, which were assigned to two groups (n = 6): bone defect treated with collagen membrane (TG) and bone defect without treatment (CONT). Then, tibiae were submitted to micro-CT. The membranes preserved their natural collagen characteristics, presenting great strength, high water absorption, hydrophilicity, and almost complete dissolution in 30 days. In the experimental study, the membrane enhanced the growth of bone tissue in contact with its surface. A higher bone volume and trabeculae number and less trabecular space was observed in bone defects of the membrane group compared to the control group at 21 days. In conclusion, the Techgraft membrane seems to have favorable characteristics for treatment of long bone repair.

Microfluidic Fabrication of Gadolinium-Doped Hydroxyapatite for Theragnostic Applications

Among the several possible uses of nanoparticulated systems in biomedicine, their potential as theragnostic agents has received significant interest in recent times. In this work, we have taken advantage of the medical applications of Gadolinium as a contrast agent with the versatility and huge array of possibilities that microfluidics can help to create doped Hydroxyapatite nanoparticles with magnetic properties in an efficient and functional way. First, with the help of Computational Fluid Dynamics (CFD), we performed a complete and precise study of all the elements and phases of our device to guarantee that our microfluidic system worked in the laminar regime and was not affected by the presence of nanoparticles through the flow requisite that is essential to guarantee homogeneous diffusion between the elements or phases in play. Then the obtained biomaterials were physiochemically characterized by means of XRD, FE-SEM, EDX, confocal Raman microscopy, and FT-IR, confirming the successful incorporation of the lanthanide element Gadolinium in part of the Ca (II) binding sites. Finally, the magnetic characterization confirmed the paramagnetic behaviour of the nanoparticles, demonstrating that, with a simple and automatized system, it is possible to obtain advanced nanomaterials that can offer a promising and innovative solution in theragnostic applications.

Recent advances in nanomaterial-based optical biosensors for food safety applications: Ochratoxin-A detection, as case study

Global population growth tremendously impacts the global food industry, endangering food safety and quality. Mycotoxins, particularly Ochratoxin-A (OTA), emerge as a food chain production threat, since it is produced by fungus that contaminates different food species and products. Beyond this, OTA exhibits a possible human toxicological risk that can lead to carcinogenic and neurological diseases. A selective, sensitive, and reliable OTA biodetection approach is essential to ensure food safety. Current detection approaches rely on accurate and time-consuming laboratory techniques performed at the end of the food production process, or lateral-flow technologies that are rapid and on-site, but do not provide quantitative and precise OTA concentration measurements. Nanoengineered optical biosensors arise as an avant-garde solution, providing high sensing performance, and a fast and accurate OTA biodetection screening, which is attractive for the industrial market. This review core presents and discusses the recent advancements in optical OTA biosensing, considering engineered nanomaterials, optical transduction principle and biorecognition methodologies. Finally, the major challenges and future trends are discussed, and current patented OTA optical biosensors are emphasized for a particular promising detection method.

Synergistic Effect of Co-Culturing Breast Cancer Cells and Fibroblasts in the Formation of Tumoroid Clusters and Design of In Vitro 3D Models for the Testing of Anticancer Agents

Breast cancer is still the leading cause of women's death due to relapse and metastasis. In vitro tumor models are considered reliable tools for drug screening and understanding cancer-driving mechanisms due to the possibility of mimicking tumor heterogeneity. Herein, a 3D breast cancer model (3D-BCM) is developed based on enzymatically-crosslinked silk fibroin (eSF) hydrogels. Human MCF7 breast cancer cells are encapsulated into eSF hydrogels, with and without human mammary fibroblasts. The spontaneously occurring conformational change from random coil to β-sheet is correlated with increased eSF hydrogels' stiffness over time. Moreover, mechanical properties analysis confirms that the cells can modify the stiffness of the hydrogels, mimicking the microenvironment stiffening occurring in vivo. Fibroblasts support cancer cells growth and assembly in the eSF hydrogels up to 14 days of culture. Co-cultured 3D-BCM exhibits an upregulated expression of genes related to extracellular matrix remodeling and fibroblast activation. The 3D-BCM is subjected to doxorubicin and paclitaxel treatments, showing differential drug response. Overall, these results suggest that the co-culture of breast cancer cells and fibroblasts in eSF hydrogels allow the development of a mimetic in vitro platform to study cancer progression. This opens up new research avenues to investigate novel molecular targets for anti-cancer therapy.

Development of Cork Biocomposites Enriched with Chitosan Targeting Antibacterial and Antifouling Properties

The demand for bio-based and safer composite materials is increasing due to the growth of the industry, human population, and environmental concerns. In this framework, sustainable and safer cork-polymer composites (CPC), based on green low-density polyethylene (LDPE) were developed using melt-based technologies. Chitosan and polyethylene-graft-maleic anhydride (PE-g-MA) were employed to enhance the CPC's properties. The morphology, wettability, mechanical, thermal, and antibacterial properties of the CPC against Pseudomonas putida (P. putida) and Staphylococcus aureus (S. aureus) were examined. The CPC showed improved stiffness when compared with that of the LDPE matrix, preferably when combined with chitosan and PE-g-MA (5 wt. %), reinforcing the stiffness (58.8%) and the strength (66.7%). Chitosan also increased the composite stiffness and strength, as well as reduced the surface hydrophilicity. The CPCs' antibacterial activity revealed that cork significantly reduces the biofilm on the polymer matrix. The highest biofilm reduction was found with CPC containing cork and 5 wt. % chitosan for both P. putida (54% reduction) and S. aureus (36% reduction), confirming their potential to extend the lifespan of products for packaging and healthcare, among other applications. This work leads to the understanding of the factors that influence biofilm formation in cork composites and provides a strategy to reinforce their behavior using chitosan.

In Vivo Skin Hydrating Efficacy of Fish Collagen from Greenland Halibut as a High-Value Active Ingredient for Cosmetic Applications

The industrial processing of fish for food purposes also generates a considerable number of by-products such as viscera, bones, scales, and skin. From a value-added perspective, fish by-products can act also as raw materials, especially because of their collagen content (particularly in fish skin). Interestingly, the potential of marine collagen for cosmetic applications is enormous and, remarkably, the extraction of this protein from fish skins has been established for different species. Using this approach, we investigated the integration of marine collagen (COLRp_I) extracted from the skin of the Greenland halibut as an active ingredient in a cosmetic hydrogel formulation. In this study, extracts of marine collagen at concentrations up to 10 mg/mL showed a non-cytotoxic effect when cultured with fibroblast cells for 3 days. In addition, marine collagen extract, when incorporated into a cosmetic hydrogel formulation, met criterion A of ISO 11930:2019 regarding the efficacy of the preservative system (challenge test). In addition, the cosmetic formulations based on marine collagen at dosages of 0.1, 0.25 and 0.5% were tested in a clinical study on the skin of the forearms of 23 healthy volunteers, showing a sightly hydration effect, suggesting its potential for beauty applications. Moreover, this work illustrates that the circular economy concept applied to the fish processing industry can represent important benefits, at innovation, environmental and economic levels.

Progress of Microfluidic Hydrogel-Based Scaffolds and Organ-on-Chips for the Cartilage Tissue Engineering

Cartilage degeneration is among the fundamental reasons behind disability and pain across the globe. Numerous approaches have been employed to treat cartilage diseases. Nevertheless, none have shown acceptable outcomes in the long run. In this regard, the convergence of tissue engineering and microfabrication principles can allow developing more advanced microfluidic technologies, thus offering attractive alternatives to current treatments and traditional constructs used in tissue engineering applications. Herein, the current developments involving microfluidic hydrogel-based scaffolds, promising structures for cartilage regeneration, ranging from hydrogels with microfluidic channels to hydrogels prepared by the microfluidic devices, that enable therapeutic delivery of cells, drugs, and growth factors, as well as cartilage-related organ-on-chips are reviewed. Thereafter, cartilage anatomy and types of damages, and present treatment options are briefly overviewed. Various hydrogels are introduced, and the advantages of microfluidic hydrogel-based scaffolds over traditional hydrogels are thoroughly discussed. Furthermore, available technologies for fabricating microfluidic hydrogel-based scaffolds and microfluidic chips are presented. The preclinical and clinical applications of microfluidic hydrogel-based scaffolds in cartilage regeneration and the development of cartilage-related microfluidic chips over time are further explained. The current developments, recent key challenges, and attractive prospects that should be considered so as to develop microfluidic systems in cartilage repair are highlighted.

Bladder Wall Stiffness after Cystectomy in Bladder Cancer Patients: A Preliminary Study

Bladder cancer (BlCa), specifically urothelial carcinomas, is a heterogeneous disease that derives from the urothelial lining. Two main classes of BlCa are acknowledged: the non-muscle invasive BlCa and the muscle-invasive BlCa; the latter constituting an aggressive disease which invades locally and metastasizes systemically. Distinguishing the specific microenvironment that cancer cells experience between mucosa and muscularis propria layers can help elucidate how these cells acquire invasive capacities. In this work, we propose to measure the micromechanical properties of both mucosa and muscularis propria layers of the bladder wall of BlCa patients, using atomic force microscopy (AFM). To do that, two cross-sections of both the macroscopically normal urinary bladder wall and the bladder wall adjacent to the tumor were collected and immediately frozen, prior to AFM samples analysis. The respective "twin" formalin-fixed paraffin-embedded tissue fragments were processed and later evaluated for histopathological examination. H&E staining suggested that tumors promoted the development of muscle-like structures in the mucosa surrounding the neoplastic region. The average Young's modulus (cell stiffness) in tumor-adjacent specimens was significantly higher in the muscularis propria than in the mucosa. Similarly, the tumor-free specimens had significantly higher Young's moduli in the muscularis propria than in the urothelium. Young's moduli were higher in all layers of tumor-adjacent tissues when compared with tumor-free samples. Here we provide insights into the stiffness of the bladder wall layers, and we show that the presence of tumor in the surrounding mucosa leads to an alteration of its smooth muscle content. The quantitative assessment of stiffness range here presented provides essential data for future research on BlCa and for understanding how the biomechanical stimuli can modulate cancer cells' capacity to invade through the different bladder layers.

Cell-Laden Marine Gelatin Methacryloyl Hydrogels Enriched with Ascorbic Acid for Corneal Stroma Regeneration

Corneal pathologies from infectious or noninfectious origin have a significant impact on the daily lives of millions of people worldwide. Despite the risk of organ rejection or infection, corneal transplantation is currently the only effective treatment. Finding safe and innovative strategies is the main goal of tissue-engineering-based approaches. In this study, the potential of gelatin methacryloyl (GelMA) hydrogels produced from marine-derived gelatin and loaded with ascorbic acid (as an enhancer of the biological activity of cells) was evaluated for corneal stromal applications. Marine GelMA was synthesized with a methacrylation degree of 75%, enabling effective photocrosslinking, and hydrogels with or without ascorbic acid were produced, encompassing human keratocytes. All the produced formulations exhibited excellent optical and swelling properties with easy handling as well as structural stability and adequate degradation rates that may allow proper extracellular matrix remodeling by corneal stromal cells. Formulations loaded with 0.5 mg/mL of ascorbic acid enhanced the biological performance of keratocytes and induced collagen production. These results suggest that, in addition to marine-derived gelatin being suitable for the synthesis of GelMA, the hydrogels produced are promising biomaterials for corneal regeneration applications.

Assessing cell migration in hydrogels: An overview of relevant materials and methods

Cell migration is essential in numerous living processes, including embryonic development, wound healing, immune responses, and cancer metastasis. From individual cells to collectively migrating epithelial sheets, the locomotion of cells is tightly regulated by multiple structural, chemical, and biological factors. However, the high complexity of this process limits the understanding of the influence of each factor. Recent advances in materials science, tissue engineering, and microtechnology have expanded the toolbox and allowed the development of biomimetic in vitro assays to investigate the mechanisms of cell migration. Particularly, three-dimensional (3D) hydrogels have demonstrated a superior ability to mimic the extracellular environment. They are therefore well suited to studying cell migration in a physiologically relevant and more straightforward manner than in vivo approaches. A myriad of synthetic and naturally derived hydrogels with heterogeneous characteristics and functional properties have been reported. The extensive portfolio of available hydrogels with different mechanical and biological properties can trigger distinct biological responses in cells affecting their locomotion dynamics in 3D. Herein, we describe the most relevant hydrogels and their associated physico-chemical characteristics typically employed to study cell migration, including established cell migration assays and tracking methods. We aim to give the reader insight into existing literature and practical details necessary for performing cell migration studies in 3D environments.

Exploiting Polyelectrolyte Complexation for the Development of Adhesive and Bioactive Membranes Envisaging Guided Tissue Regeneration

Mussels secrete protein-based byssal threads to tether to rocks, ships, and other organisms underwater. The secreted marine mussel adhesive proteins (MAPs) contain the peculiar amino acid L-3,4-dihydroxyphenylalanine (DOPA), whose catechol group content contributes greatly to their outstanding adhesive properties. Inspired by such mussel bioadhesion, we demonstrate that catechol-modified polysaccharides can be used to obtain adhesive membranes using the compaction of polyelectrolyte complexes (CoPEC) method. It is a simple and versatile approach that uses polyelectrolyte complexes as building blocks that coalesce and dry as membrane constructs simply as a result of sedimentation and mild temperature. We used two natural and biocompatible polymers: chitosan (CHI) as a polycation and hyaluronic acid (HA) as a polyanion. The CoPEC technique also allowed the entrapment of ternary bioactive glass nanoparticles to stimulate mineralization. Moreover, combinations of these polymers modified with catechol groups were made to enhance the adhesive properties of the assembled membranes. Extensive physico-chemical characterization was performed to investigate the successful production of composite CoPEC membranes in terms of surface morphology, wettability, stability, mechanical performance, in vitro bioactivity, and cellular behavior. Considering the promising properties exhibited by the obtained membranes, new adhesives suitable for the regeneration of hard tissues can be envisaged.

Special Issue: Tissue Engineered Biomaterials and Drug Delivery Systems

Current advances in biomaterials processing and engineering for drug delivery have allowed interesting progressed in biomedical field [...].

Translation of biomaterials from bench to clinic

Scientific research originates from curiosity and interests. Translational research of biomaterials should always focus on addressing specific needs of the targeted clinical applications. The guest editors of this special issue hope that the included articles have provided cutting-edge biomaterials research as well as insights of the translation of biomaterials from bench to clinic.

Efficacy of molecular and nano-therapies on brain tumor models in microfluidic devices

The three-dimensional (3D) organization of cells affects their mobility, proliferation, and overall response to treatment. Spheroids, organoids, and microfluidic chips are used in cancer research to reproduce in vitro the complex and dynamic malignant microenvironment. Herein, single- and double-channel microfluidic devices are used to mimic the spatial organization of brain tumors and investigate the therapeutic efficacy of molecular and nano anti-cancer agents. Human glioblastoma multiforme (U87-MG) cells were cultured into a Matrigel matrix embedded within the microfluidic devices and exposed to different doses of free docetaxel (DTXL), docetaxel-loaded spherical polymeric nanoparticles (DTXL-SPN), and the aromatic N-glucoside N-(fluorenylmethoxycarbonyl)-glucosamine-6-phosphate (Fmoc-Glc6P). We observed that in the single-channel microfluidic device, brain tumor cells are more susceptible to DTXL treatment as compared to conventional cell monolayers (50-fold lower IC₅₀ values). In the double-channel device, the cytotoxicity of free DTXL and DTXL-SPN is comparable, but significantly lowered as compared to the single-channel configuration. Finally, the administration of 500 μM Fmoc-Glc6P in the double-channel microfluidic device shows a 50 % U87-MG cell survival after only 24 h, and no deleterious effect on human astrocytes over 72 h. Concluding, the proposed microfluidic chips can be used to reproduce the 3D complex spatial arrangement of solid tumors and to assess the anti-cancer efficacy of therapeutic compounds administrated in situ or systemically.

3D Biocomposites Comprising Marine Collagen and Silica-Based Materials Inspired on the Composition of Marine Sponge Skeletons Envisaging Bone Tissue Regeneration

Ocean resources are a priceless repository of unique species and bioactive compounds with denouement properties that can be used in the fabrication of advanced biomaterials as new templates for supporting the cell culture envisaging tissue engineering approaches. The collagen of marine origin can be sustainably isolated from the underrated fish processing industry by-products, while silica and related materials can be found in the spicules of marine sponges and diatoms frustules. Aiming to address the potential of biomaterials composed from marine collagen and silica-based materials in the context of bone regeneration, four different 3D porous structure formulations (COL, COL:BG, COL:D.E, and COL:BS) were fabricated by freeze-drying. The skins of Atlantic cod (Gadus morhua) were used as raw materials for the collagen (COL) isolation, which was successfully characterized by SDS-PAGE, FTIR, CD, and amino acid analyses, and identified as a type I collagen, produced with a 1.5% yield and a preserved characteristic triple helix conformation. Bioactive glass 45S5 bioglass® (BG), diatomaceous earth (D.E.) powder, and biosilica (BS) isolated from the Axinella infundibuliformis sponge were chosen as silica-based materials, which were obtained as microparticles and characterized by distinct morphological features. The biomaterials revealed microporous structures, showing a porosity higher than 85%, a mean pore size range of 138-315 μm depending on their composition, with 70% interconnectivity which can be favorable for cell migration and ensure the needed nutrient supply. In vitro, biological assays were conducted by culturing L929 fibroblast-like cells, which confirmed not only the non-toxic nature of the developed biomaterials but also their capability to support cell adhesion and proliferation, particularly the COL:BS biomaterials, as observed by calcein-AM staining upon seven days of culture. Moreover, phalloidin and DAPI staining revealed well-spread cells, populating the entire construct. This study established marine collagen/silica biocomposites as potential scaffolds for tissue engineering, setting the basis for future studies, particularly envisaging the regeneration of non-load-bearing bone tissues.

On the Bioactivity of Echinacea purpurea Extracts to Modulate the Production of Inflammatory Mediators

Inflammatory diseases are the focus of several clinical studies, due to limitations and serious side effects of available therapies. Plant-based drugs (e.g., salicylic acid, morphine) have become landmarks in the pharmaceutical field. Therefore, we investigated the immunomodulatory effects of flowers, leaves, and roots from Echinacea purpurea. Ethanolic (EE) and dichloromethanolic extracts (DE) were obtained using the Accelerated Solvent Extractor and aqueous extracts (AE) were prepared under stirring. Their chemical fingerprint was evaluated by liquid chromatography-high resolution mass spectrometry (LC-HRMS). The pro- and anti-inflammatory effects, as well as the reduction in intracellular reactive oxygen and nitrogen species (ROS/RNS), of the different extracts were evaluated using non-stimulated and lipopolysaccharide-stimulated macrophages. Interestingly, AE were able to stimulate macrophages to produce pro-inflammatory cytokines (tumor necrosis factor -TNF-α, interleukin -IL-1β, and IL-6), and to generate ROS/RNS. Conversely, under an inflammatory scenario, all extracts reduced the amount of pro-inflammatory mediators. DE, alkylamides-enriched extracts, showed the strongest anti-inflammatory activity. Moreover, E. purpurea extracts demonstrated generally a more robust anti-inflammatory activity than clinically used anti-inflammatory drugs (dexamethasone, diclofenac, salicylic acid, and celecoxib). Therefore, E. purpurea extracts may be used to develop new effective therapeutic formulations for disorders in which the immune system is either overactive or impaired.

Antibacterial nanopatterned coatings for dental implants

Dental implants, usually made of titanium, are exposed to hostile oral microflora that facilitate bacterial infections and subsequent inflammation. To mitigate these processes, we coated titanium substrates with block copolymer nanopatterns and investigated the bactericidal effect of these coatings against Gram-positive and Gram-negative bacteria. We found that the bactericidal efficacy of the coatings depends on their morphology and surface chemistry as well as on the bacterial strain: an optimal combination can lead to significant bacterial death for a short time, i.e. 90% for 90 min. Human gingival fibroblasts in contact with the nanopatterned coatings showed similar cell attachment and morphology as on bare Ti. Immunostaining assays showed similar levels of CCR7 and CD206 in macrophages cultured over the nanopatterns and bare Ti, demonstrating adequate properties for tissue integration. The nanopatterns induced a small increase in macrophage aspect ratio, which might indicate early states of M2 polarization, given the absence of CD206.