Evaluation of immunoreactivity of in vitro and in vivo models against bacterial synthesized cellulose to be used as a prosthetic biomaterial

Bacterial cellulose films for L-asparaginase delivery to melanoma cells

L-asparaginase (L-ASNase) is an enzyme that catalyzes the hydrolysis of L-asparagine to L-aspartic acid and ammonia and is used to treat acute lymphoblastic leukemia. It is also toxic to the cells of some solid tumors, including melanoma cells. Immobilization of this enzyme can improve its activity against melanoma tumor cells. In this work, the properties of bacterial cellulose (BC) and feasibility of BC films as a new carrier for immobilized L-ASNase were investigated. Different values of growth time were used to obtain BC films with different thicknesses and porosities, which determine the water content and the ability to adsorb and release L-ASNase. Fourier transform infrared spectroscopy confirmed the adsorption of the enzyme on the BC films. The total activity of adsorbed L-ASNase and its release were investigated for films grown for 48, 72 or 96 h. BC films grown for 96 h showed the most pronounced release as described by zero-order and Korsmayer-Peppas models. The release was characterized by controlled diffusion where the drug was released at a constant rate. BC films with immobilized L-ASNase could induce cytotoxicity in A875 human melanoma cells. With further development, immobilization of L-ASNase on BC may become a potent strategy for anticancer drug delivery to superficial tumors.

Protein Immobilization on Bacterial Cellulose for Biomedical Application

New carriers for protein immobilization are objects of interest in various fields of biomedicine. Immobilization is a technique used to stabilize and provide physical support for biological micro- and macromolecules and whole cells. Special efforts have been made to develop new materials for protein immobilization that are non-toxic to both the body and the environment, inexpensive, readily available, and easy to modify. Currently, biodegradable and non-toxic polymers, including cellulose, are widely used for protein immobilization. Bacterial cellulose (BC) is a natural polymer with excellent biocompatibility, purity, high porosity, high water uptake capacity, non-immunogenicity, and ease of production and modification. BC is composed of glucose units and does not contain lignin or hemicellulose, which is an advantage allowing the avoidance of the chemical purification step before use. Recently, BC-protein composites have been developed as wound dressings, tissue engineering scaffolds, three-dimensional (3D) cell culture systems, drug delivery systems, and enzyme immobilization matrices. Proteins or peptides are often added to polymeric scaffolds to improve their biocompatibility and biological, physical-chemical, and mechanical properties. To broaden BC applications, various ex situ and in situ modifications of native BC are used to improve its properties for a specific application. In vivo studies showed that several BC-protein composites exhibited excellent biocompatibility, demonstrated prolonged treatment time, and increased the survival of animals. Today, there are several patents and commercial BC-based composites for wounds and vascular grafts. Therefore, further research on BC-protein composites has great prospects. This review focuses on the major advances in protein immobilization on BC for biomedical applications.

Detection of typical indigenous gut bacteria related to kanpyo Lagenaria siceraria var. hispida powder in murine caecum and human faecal cultures

Kanpyo (KP) is an edible dried product produced by peeling the fruit of the gourd Lagenaria siceraria var. hispida; it is used in the traditional Japanese cuisine. The health functionality of KP due to its rich dietary fibre is expected to include a possible combined effect of KP-responsive indigenous gut bacteria (KP-RIB). However, its effect on the gut microbiota is unclear. To determine the effects of the KP on the gut microbiota and their host, Institute of Cancer Research mice were fed a high-sucrose diet containing no fibre (NF) or 5% (w/w) KP for 14 days, and their caecal microbiota was analysed by 16S rRNA (V4) amplicon sequencing. Higher faecal frequency and weight and lower spleen weight and spleen tumour necrosis factor-α levels were observed in KP-fed mice than in NF-fed mice (p < 0.05). KP increased and decreased the abundance of short-chain fatty acid producer Lachnospiraceae and obesity-inflammation related Allobaculum species, respectively. In the case of human faecal cultures, stool samples from five healthy volunteers were inoculated and incubated at 37 °C for 24 h anaerobically; 3.2% (w/v) KP suppressed putrefactive compounds (indole, phenol, and ammonia). KP increased butyrate-producer Faecalibacterium, acetate/lactate-producer Bifidobacterium, and Lachnospira. Furthermore, KP cultures showed high antioxidant and RAW264.7 macrophage cell activation capacities. These results suggest that KP-RIB and KP intake may synergistically affect host health. However, further studies are required to clarify the synergistic effects of KP and KP-RIB.

Nanocellulose-stabilized Pickering emulsions: Fabrication, stabilization, and food applications

Pickering emulsions have been widely studied due to their good stability and potential applications. Nanocellulose including cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and bacterial cellulose nanofibrils (BCNFs) has emerged as sustainable stabilizers/emulsifiers in food-related Pickering emulsions due to their favorable properties such as renewability, low toxicity, amphiphilicity, biocompatibility, and high aspect ratio. Nanocellulose can be widely obtained from different sources and extraction methods and can effectively stabilize Pickering emulsions via the irreversible adsorption onto oil-water interface. The synergistic effects of nanocellulose and other substances can further enhance the interfacial networks. The nanocellulose-based Pickering emulsions have potential food-related applications in delivery systems, food packaging materials, and fat substitutes. Nanocellulose-based Pickering emulsions as 3D printing inks exhibit good injectable and gelling properties and are promising to print spatial architectures. In the future, the utilization of biomass waste and the development of "green" and facile extraction methods for nanocellulose production deserve more attention. The stability of nanocellulose-based Pickering emulsions in multi-component food systems and at various conditions is an utmost challenge. Moreover, the case-by-case studies on the potential safety issues of nanocellulose-based Pickering emulsions need to be carried out with the standardized assessment procedures. In this review, we highlight key fundamental work and recent reports on nanocellulose-based Pickering emulsion systems. The sources and extraction of nanocellulose and the fabrication of nanocellulose-based Pickering emulsions are briefly summarized. Furthermore, the synergistic stability and food-related applications of nanocellulose-stabilized Pickering emulsions are spotlighted.

Opportunities for bacterial nanocellulose in biomedical applications: Review on biosynthesis, modification and challenges

Bacterial nanocellulose (BNC) is a natural polysaccharide produced as extracellular material by bacterial strains and has favorable intrinsic properties for primary use in biomedical applications. In this review, an update on state-of-the art and challenges in BNC production, surface modification and biomedical application is given. Recent insights in biosynthesis allowed for better understanding of governing parameters improving production efficiency. In particular, introduction of different carbon/nitrogen sources from alternative feedstock and industrial upscaling of various production methods is challenging. It is important to have control on the morphology, porosity and forms of BNC depending on biosynthesis conditions, depending on selection of bacterial strains, reactor design, additives and culture conditions. The BNC is intrinsically characterized by high water absorption capacity, good thermal and mechanical stability, biocompatibility and biodegradability to certain extent. However, additional chemical and/or physical surface modifications are required to improve cell compatibility, protein interaction and antimicrobial properties. The novel trends in synthesis include the in-situ culturing of hybrid BNC nanocomposites in combination with organic material, inorganic material or extracellular components. In parallel with toxicity studies, the applications of BNC in wound care, tissue engineering, medical implants, drug delivery systems or carriers for bioactive compounds, and platforms for biosensors are highlighted.

Tracking Bacterial Nanocellulose in Animal Tissues by Fluorescence Microscopy

The potential of nanomaterials in food technology is nowadays well-established. However, their commercial use requires a careful risk assessment, in particular concerning the fate of nanomaterials in the human body. Bacterial nanocellulose (BNC), a nanofibrillar polysaccharide, has been used as a food product for many years in Asia. However, given its nano-character, several toxicological studies must be performed, according to the European Food Safety Agency’s guidance. Those should especially answer the question of whether nanoparticulate cellulose is absorbed in the gastrointestinal tract. This raises the need to develop a screening technique capable of detecting isolated nanosized particles in biological tissues. Herein, the potential of a cellulose-binding module fused to a green fluorescent protein (GFP–CBM) to detect single bacterial cellulose nanocrystals (BCNC) obtained by acid hydrolysis was assessed. Adsorption studies were performed to characterize the interaction of GFP–CBM with BNC and BCNC. Correlative electron light microscopy was used to demonstrate that isolated BCNC may be detected by fluorescence microscopy. The uptake of BCNC by macrophages was also assessed. Finally, an exploratory 21-day repeated-dose study was performed, wherein Wistar rats were fed daily with BNC. The presence of BNC or BCNC throughout the GIT was observed only in the intestinal lumen, suggesting that cellulose particles were not absorbed. While a more comprehensive toxicological study is necessary, these results strengthen the idea that BNC can be considered a safe food additive.

In Vitro Cytotoxicity, Colonisation by Fibroblasts and Antimicrobial Properties of Surgical Meshes Coated with Bacterial Cellulose

Hernia repairs are the most common abdominal wall elective procedures performed by general surgeons. Hernia-related postoperative infective complications occur with 10% frequency. To counteract the risk of infection emergence, the development of effective, biocompatible and antimicrobial mesh adjuvants is required. Therefore, the aim of our in vitro investigation was to evaluate the suitability of bacterial cellulose (BC) polymer coupled with gentamicin (GM) antibiotic as an absorbent layer of surgical mesh. Our research included the assessment of GM-BC-modified meshes’ cytotoxicity against fibroblasts ATCC CCL-1 and a 60-day duration cell colonisation measurement. The obtained results showed no cytotoxic effect of modified meshes. The quantified fibroblast cells levels resembled a bimodal distribution depending on the time of culturing and the type of mesh applied. The measured GM minimal inhibitory concentration was 0.47 µg/mL. Results obtained in the modified disc-diffusion method showed that GM-BC-modified meshes inhibited bacterial growth more effectively than non-coated meshes. The results of our study indicate that BC-modified hernia meshes, fortified with appropriate antimicrobial, may be applied as effective implants in hernia surgery, preventing risk of infection occurrence and providing a high level of biocompatibility with regard to fibroblast cells.

Biofunctionalised bacterial cellulose scaffold supports the patterning and expansion of human embryonic stem cell-derived dopaminergic progenitor cells

BACKGROUND

Stem cell-based therapies for neurodegenerative diseases like Parkinson's disease are a promising approach in regenerative medicine and are now moving towards early stage clinical trials. However, a number of challenges remain including the ability to grow stem cells in vitro on a 3-dimensional scaffold, as well as their loss, by leakage or cell death, post-implantation. These issues could, however, be helped through the use of scaffolds that support the growth and differentiation of stem cells both in vitro and in vivo. The present study focuses on the use of bacterial cellulose as an in vitro scaffold to promote the growth of different stem cell-derived cell types. Bacterial cellulose was used because of its remarkable properties such as its wettability, ability to retain water and low stiffness, all of which is similar to that found in brain tissue.

METHODS

We cultured human embryonic stem cell-derived progenitor cells on bacterial cellulose with growth factors that were covalently functionalised to the surface via silanisation. Epifluorescence microscopy and immunofluorescence were used to detect the differentiation of stem cells into dopaminergic ventral midbrain progenitor cells. We then quantified the proportion of cells that differentiated into progenitor cells and compared the effect of growing cells on biofunctionalised cellulose versus standard cellulose.

RESULTS

We show that the covalent functionalisation of bacterial cellulose sheets with bioactive peptides improves the growth and differentiation of human pluripotent stem cells into dopaminergic neuronal progenitors.

CONCLUSIONS

This study suggests that the biocompatible material, bacterial cellulose, has potential applications in cell therapy approaches as a means to repair damage to the central nervous system, such as in Parkinson's disease but also in tissue engineering.

Recent Advances in the Synthesis of Nanocellulose Functionalized–Hybrid Membranes and Application in Water Quality Improvement

The increasing discharge of voluminous non or partially treated wastewaters characterized by complex contaminants poses significant ecological and health risks. Particularly, this practice impacts negatively on socio-economic, technological, industrial, and agricultural development. Therefore, effective control of water pollution is imperative. Over the past decade, membrane filtration has been established as an effective and commercially attractive technology for the separation and purification of water. The performance of membrane-based technologies relies on the intrinsic properties of the membrane barrier itself. As a result, the development of innovative techniques for the preparation of highly efficient membranes has received remarkable attention. Moreover, growing concerns related to cost-effective and greener technologies have induced the need for eco-friendly, renewable, biodegradable, and sustainable source materials for membrane fabrication. Recently, advances in nanotechnology have led to the development of new high-tech nanomaterials from natural polymers (e.g., cellulose) for the preparation of environmentally benign nanocomposite membranes. The synthesis of nanocomposite membranes using nanocelluloses (NCs) has become a prominent research field. This is attributed to the exceptional characteristics of these nanomaterials (NMs) namely; excellent and tuneable surface chemistry, high mechanical strength, low-cost, biodegradability, biocompatibility, and renewability. For this purpose, the current paper opens with a comprehensive yet concise description of the various types of NCs and their most broadly utilized production techniques. This is closely followed by a critical review of how NC substrates and their surface-modified versions affect the performance of the fabricated NC-based membranes in various filtration processes. Finally, the most recent processing technologies for the preparation of functionalized NCs-based composite membranes are discussed in detail and their hybrid characteristics relevant to membrane filtration processes are highlighted.

Immunological aspects of nanocellulose

Cellulose is the most abundant natural polymer in the world. Nanoscale forms of cellulose, including cellulose nanofibers (CNF), cellulose nanocrystals (CNC) and bacterial nanocellulose (BC), are very attractive in industry, medicine and pharmacy. Biomedical applications of nanocellulose in tissue engineering, regenerative medicine, and controlled drug delivery are the most promising. Nanocellulose is considered a biocompatible nanomaterial and relatively safe for biomedical applications. However, more studies are needed to prove this hypothesis, especially those related to chronic exposure to nanocellulose. Besides toxicity, the response of the immune system is of particular importance in this sense. This paper provides a comprehensive and critical review of the current-state knowledge of the impact of nanocellulose on the immune system, especially on macrophages and dendritic cells (DC), as the central immunoregulatory cells, which has not been addressed in the literature sufficiently. Nanocellulose, especially CNC, can induce the inflammatory response upon the internalization by macrophages, but this reaction may be significantly modulated by introducing different functional groups on their surface. Our original results showed that nanocellulose has a potent immunotolerogenic potential. Native CNF potentiated the capacity of DC to induce conventional Tregs. When carboxyl groups were introduced on the CNF surface, the tolerogenic potential of DC was shifted towards the induction of regulatory CD8⁺ T cells, whereas the introduction of phosphonates on CNF surface potentiated DCs' capacity to induce both regulatory CD8⁺ T cells and Type 1 regulatory (Tr-1) cells. These results are extremely important when considering the application of nanocellulose in vivo, especially for tissue regeneration and wound healing.

Natural Polysaccharide Nanomaterials: An Overview of Their Immunological Properties

Natural occurring polymers, or biopolymers, represent a huge part of our planet biomass. They are formed by long chains of monomers of the same type or a combination of different ones. Polysaccharides are biopolymers characterized by complex secondary structures performing several roles in plants, animals, and microorganisms. Because of their versatility and biodegradability, some of them are extensively used for packaging, food, pharmaceutical, and biomedical industries as sustainable and renewable materials. In the recent years, their manipulation at the nanometric scale enormously increased the range of potential applications, boosting an interdisciplinary research attempt to exploit all the potential advantages of nanostructured polysaccharides. Biomedical investigation mainly focused on nano-objects aimed at drug delivery, tissue repair, and vaccine adjuvants. The achievement of all these applications requires the deep knowledge of polysaccharide nanomaterials' interactions with the immune system, which orchestrates the biological response to any foreign substance entering the body. In the present manuscript we focused on natural polysaccharides of high commercial importance, namely, starch, cellulose, chitin, and its deacetylated form chitosan, as well as the seaweed-derived carrageenan and alginate. We reviewed the available information on their biocompatibility, highlighting the importance of their physicochemical feature at the nanoscale for the modulation of the immune system.

Recent advances in nanoengineering cellulose for cargo delivery

The recent decade has witnessed a growing demand to substitute synthetic materials with naturally-derived platforms for minimizing their undesirable footprints in biomedicine, environment, and ecosystems. Among the natural materials, cellulose, the most abundant biopolymer in the world with key properties, such as biocompatibility, biorenewability, and sustainability has drawn significant attention. The hierarchical structure of cellulose fibers, one of the main constituents of plant cell walls, has been nanoengineered and broken down to nanoscale building blocks, providing an infrastructure for nanomedicine. Microorganisms, such as certain types of bacteria, are another source of nanocelluloses known as bacterial nanocellulose (BNC), which benefit from high purity and crystallinity. Chemical and mechanical treatments of cellulose fibrils made up of alternating crystalline and amorphous regions have yielded cellulose nanocrystals (CNC), hairy CNC (HCNC), and cellulose nanofibrils (CNF) with dimensions spanning from a few nanometers up to several microns. Cellulose nanocrystals and nanofibrils may readily bind drugs, proteins, and nanoparticles through physical interactions or be chemically modified to covalently accommodate cargos. Engineering surface properties, such as chemical functionality, charge, area, crystallinity, and hydrophilicity, plays a pivotal role in controlling the cargo loading/releasing capacity and rate, stability, toxicity, immunogenicity, and biodegradation of nanocellulose-based delivery platforms. This review provides insights into the recent advances in nanoengineering cellulose crystals and fibrils to develop vehicles, encompassing colloidal nanoparticles, hydrogels, aerogels, films, coatings, capsules, and membranes, for the delivery of a broad range of bioactive cargos, such as chemotherapeutic drugs, anti-inflammatory agents, antibacterial compounds, and probiotics. SYNOPSIS: Engineering certain types of microorganisms as well as the hierarchical structure of cellulose fibers, one of the main building blocks of plant cell walls, has yielded unique families of cellulose-based nanomaterials, which have leveraged the effective delivery of bioactive molecules.

Inhalation of Bacterial Cellulose Nanofibrils Triggers an Inflammatory Response and Changes Lung Tissue Morphology of Mice

In view of the growing industrial use of Bacterial cellulose (BC), and taking into account that it might become airborne and be inhaled after industrial processing, assessing its potential pulmonary toxic effects assumes high relevance. In this work, the murine model was used to assess the effects of exposure to respirable BC nanofibrils (nBC), obtained by disintegration of BC produced by Komagataeibacter hansenii. Murine bone marrow-derived macrophages (BMMΦ) were treated with different doses of nBC (0.02 and 0.2 mg/mL, respectively 1 and 10 μg of fibrils) in absence or presence of 0.2% Carboxymethyl Cellulose (nBCMC). Furthermore, mice were instilled intratracheally with nBC or nBCMC at different concentrations and at different time-points and analyzed up to 6 months after treatments. Microcrystaline Avicel-plus® CM 2159, a plant-derived cellulose, was used for comparison. Markers of cellular damage (lactate dehydrogenase release and total protein) and oxidative stress (hydrogen peroxidase, reduced glutathione, lipid peroxidation and glutathione peroxidase activity) as well presence of inflammatory cells were evaluated in brochoalveolar lavage (BAL) fluids. Histological analysis of lungs, heart and liver tissues was also performed. BAL analysis showed that exposure to nBCMC or CMC did not induce major alterations in the assessed markers of cell damage, oxidative stress or inflammatory cell numbers in BAL fluid over time, even following cumulative treatments. Avicel-plus® CM 2159 significantly increased LDH release, detected 3 months after 4 weekly administrations. However, histological results revealed a chronic inflammatory response and tissue alterations, being hypertrophy of pulmonary arteries (observed 3 months after nBCMC treatment) of particular concern. These histological alterations remained after 6 months in animals treated with nBC, possibly due to foreign body reaction and the organism's inability to remove the fibers. Overall, despite being a safe and biocompatible biomaterial, BC-derived nanofibrils inhalation may lead to lung pathology and pose significant health risks.

DETC-based bacterial cellulose bio-curatives for topical treatment of cutaneous leishmaniasis

The treatment of leishmaniasis still relies on drugs with potentially serious adverse effects. Herein, we tested a topical formulation of bacterial cellulose (BC) membranes containing Diethyldithiocarbamate (DETC), a superoxide dismutase 1 inhibitor. Leishmania-infected macrophages exposed to BC-DETC resulted in parasite killing, without pronounced toxic effects to host cells. This outcome was associated with lower SOD1 activity and higher production of superoxide and cytokine mediators. Topical application of BC-DETC significantly decreased lesion size, parasite load and the inflammatory response at the infection site, as well as the production of both IFN-γ and TNF. Combination of topical BC-DETC plus intraperitoneal Sb^v also significantly reduced disease development and parasite load. The leishmanicidal effect of BC-DETC was extended to human macrophages infected with L. braziliensis, highlighting the feasibility of BC-DETC as a topical formulation for chemotherapy of cutaneous leishmaniasis caused by L. braziliensis.

In situ and ex situ modifications of bacterial cellulose for applications in tissue engineering

Bacterial cellulose (BC) is secreted by a few strains of bacteria and consists of a cellulose nanofiber network with unique characteristics. Because of its excellent mechanical properties, outstanding biocompatibilities, and abilities to form porous structures, BC has been studied for a variety of applications in different fields, including the use as a biomaterial for scaffolds in tissue engineering. To extend its applications in tissue engineering, native BC is normally modified to enhance its properties. Generally, BC modifications can be made by either in situ modification during cell culture or ex situ modification of existing BC microfibers. In this review we will first provide a brief introduction of BC and its attributes; this will set the stage for in-depth and up-to-date discussions on modified BC. Finally, the review will focus on in situ and ex situ modifications of BC and its applications in tissue engineering, particularly in bone regeneration and wound dressing.

Applications of bacterial cellulose and its composites in biomedicine

Bacterial cellulose produced by few but specific microbial genera is an extremely pure natural exopolysaccharide. Besides providing adhesive properties and a competitive advantage to the cellulose over-producer, bacterial cellulose confers UV protection, ensures maintenance of an aerobic environment, retains moisture, protects against heavy metal stress, etc. This unique nanostructured matrix is being widely explored for various medical and nonmedical applications. It can be produced in various shapes and forms because of which it finds varied uses in biomedicine. The attributes of bacterial cellulose such as biocompatibility, haemocompatibility, mechanical strength, microporosity and biodegradability with its unique surface chemistry make it ideally suited for a plethora of biomedical applications. This review highlights these qualities of bacterial cellulose in detail with emphasis on reports that prove its utility in biomedicine. It also gives an in-depth account of various biomedical applications ranging from implants and scaffolds for tissue engineering, carriers for drug delivery, wound-dressing materials, etc. that are reported until date. Besides, perspectives on limitations of commercialisation of bacterial cellulose have been presented. This review is also an update on the variety of low-cost substrates used for production of bacterial cellulose and its nonmedical applications and includes patents and commercial products based on bacterial cellulose.