From the sea to the bee: Gellan gum-honey-diatom composite to deliver resveratrol for cartilage regeneration under oxidative stress conditions

Effectiveness of gellan gum scaffolds loaded with Boswellia serrata extract for in-situ modulation of pro-inflammatory pathways affecting cartilage healing

In this study, we developed a composite hydrogel based on Gellan gum containing Boswellia serrata extract (BSE). BSE was either incorporated directly or loaded into an MgAl-layered double hydroxide (LDH) clay to create a multifunctional cartilage substitute. This composite was designed to provide anti-inflammatory properties while enhancing chondrogenesis. Additionally, LDH was exploited to facilitate the loading of hydrophobic BSE components and to improve the hydrogel's mechanical properties. A calcination process was also adopted on LDH to increase BSE loading. Physicochemical and mechanical characterizations were performed by spectroscopic (XPS and FTIR), thermogravimetric, rheological, compression test, weight loss and morphological (SEM) investigations. RPLC-ESI-FTMS was employed to investigate the boswellic acids release in simulated synovial fluid. The composites were cytocompatible and capable of supporting the mesenchymal stem cells (hMSC) growth in a 3D-conformation. Loading BSE resulted in the modulation of the pro-inflammatory cascade by down-regulating COX2, PGE2 and IL1β. Chondrogenesis studies demonstrated an enhanced differentiation, leading to the up-regulation of COL 2 and ACAN. This effect was attributed to the efficacy of BSE in reducing the inflammation through PGE2 down-regulation and IL10 up-regulation. Proteomics studies confirmed gene expression findings by revealing an anti-inflammatory protein signature during chondrogenesis of the cells cultivated onto loaded specimens. Concluding, BSE-loaded composites hold promise as a tool for the in-situ modulation of the inflammatory cascade while preserving cartilage healing.

Natural polyphenols for drug delivery and tissue engineering construction: A review

Polyphenols, natural compounds rich in phenolic structures, are gaining prominence due to their antioxidant, anti-inflammatory, antibacterial, and anticancer properties, making them valuable in biomedical applications. Through covalent and noncovalent interactions, polyphenols can bind to biomaterials, enhancing their performance and compensating for their shortcomings. Such polyphenol-based biomaterials not only increase the efficacy of polyphenols but also improve drug stability, control release kinetics, and boost the therapeutic effects of drugs. They offer the potential for targeted drug delivery, reducing off-target impacts and enhancing therapeutic outcomes. In tissue engineering, polyphenols promote cell adhesion, proliferation, and differentiation, thus aiding in the formation of functional tissues. Additionally, they offer excellent biocompatibility and mechanical strength, essential in designing scaffolds. This review explores the significant roles of polyphenols in tissue engineering and drug delivery, emphasizing their potential in advancing biomedical research and healthcare.

Advances in tissue engineering of gellan gum-based hydrogels

Gellan Gum (GG) is a large, naturally occurring, linear polysaccharide with a similar structure and biological properties to the extracellular matrix. It's appropriate as a matrix material for the development of different composite materials due to its biocompatibility, biodegradability, and injectability. Hydrogels made from GG have found various applications in the field of Tissue Engineering (TE) in recent years after being mixed with a variety of other organic and inorganic components. These composites are considered multifunctional developing biomaterials because of their impressive mechanical capabilities, biocompatibility, low cytotoxicity, etc. This review focuses on the emerging advances of GG-based hydrogels in TE, providing an overview of the applications of different types of GG-based composite materials in bone TE, cartilage TE, nervous TE, retina TE, and other fields. Moreover, the investigations of GG-based hydrogels as bioink components for 3D bioprinting in TE will be elucidated. This review offers general guidance for the development of biomaterials related to GG, as well as ideas for future clinical diagnosis and treatment.

Marine polysaccharides, proteins, lipids, and silica for drug delivery systems: A review

Marine environments represent an incredible source of biopolymers with potential biomedical applications. Recently, drug delivery studies have received great attention for the increasing need to improve site specificity, therapeutic value, and bioavailability, reducing off-target effects. Marine polymers, such as alginate, carrageenan, collagen, chitosan, and silica, have reported unique biochemical features, allowing an efficient binding with drugs, and a controlled release to the target tissue, also obtainable through "green processes". In the present review, we i) analysed the last ten years of scientific peer-reviewed literature; ii) divided the articles based on the achieved experimental phases, tagged as chemistry, drug release, and drug delivery, and iii) compared the best performances among marine polymers extracted from micro- and macro-organisms. Many reviews describe drug carriers from marine organisms, focusing on a single biopolymer or a chemical class. Our study is a groundbreaking literature collection, representing the first thorough investigation of all marine biopolymers described. Most articles report experimental results on the chemical characterisation of marine biopolymers and their in vitro behaviour as drug carriers, although development processes and commercial applications are still in the early stages. Hence, the next efforts should be focused on the sustainable production of marine polymers and final product development.

Development, Analytical Characterization, and Bioactivity Evaluation of Boswellia serrata Extract-Layered Double Hydroxide Hybrid Composites

Boswellia serrata Roxb. extract (BSE), rich in boswellic acids, is well known as a potent anti-inflammatory natural drug. However, due to its limited aqueous solubility, BSE inclusion into an appropriate carrier, capable of improving its release in the biological target, would be highly desirable. Starting with this requirement, new hybrid composites based on the inclusion of BSE in a lamellar solid layered double hydroxide (LDH), i.e., magnesium aluminum carbonate, were developed and characterized in the present work. The adopted LDH exhibited a layered crystal structure, comprising positively charged hydroxide layers and interlayers composed of carbonate anions and water molecules; thus, it was expected to embed negatively charged boswellic acids. In the present case, a calcination process was also adopted on the LDH to increase organic acid loading, based on the replacement of the original inorganic anions. An accurate investigation was carried out by TGA, PXRD, FT-IR/ATR, XPS, SEM, and LC-MS to ascertain the nature, interaction, and quantification of the active molecules of the vegetal extract loaded in the developed hybrid materials. As a result, the significant disruption of the original layered structure was observed in the LDH subjected to calcination (LDHc), and this material was able to include a higher amount of organic acids when its composite with BSE was prepared. However, in vitro tests on the composites' bioactivity, expressed in terms of antimicrobial and anti-inflammatory activity, evidenced LDH-BSE as a better material compared to BSE and to LDHc-BSE, thus suggesting that, although the embedded organic acid amount was lower, they could be more available since they were not firmly bound to the clay. The composite was able to significantly decrease the number of viable pathogens such as Escherichia coli and Staphylococcus aureus, as well as the internalization of toxic active species into human cells imposing oxidative stress, in comparison to the BSE.

Progress and opportunities in Gellan gum-based materials: A review of preparation, characterization and emerging applications

Gellan gum, a microbial exopolysaccharide, is biodegradable and has potential to fill several key roles in many fields from food to pharmacy, biomedicine and tissue engineering. In order to improve the physicochemical and biological properties of gellan gum, some researchers take advantage of numerous hydroxyl groups and the free carboxyl present in each repeating unit. As a result, design and development of gellan-based materials have advanced significantly. The goal of this review is to provide a summary of the most recent, high-quality research trends that have used gellan gum as a polymeric component in the design of numerous cutting-edge materials with applications in various fields.

Conferring Antioxidant Activity to an Antibacterial and Bioactive Titanium Surface through the Grafting of a Natural Extract

The main unmet medical need of bone implants is multifunctional activity, including their ability to induce rapid and physiological osseointegration, counteract bacterial biofilm formation, and prevent in situ chronic inflammation at the same time. This research starts from an already developed c.p. titanium surface with proven bioactive (in vitro hydroxyl apatite precipitation) and antibacterial activities, due to a calcium titanate layer with nano- and micro-scale roughness and loaded with iodine ions. Here, antioxidant ability was added to prevent chronic inflammation by grafting polyphenols of a green tea extract onto the surface, without compromising the other functionalities of the surface. The surface was characterized before and after functionalization through XPS analysis, zeta potential titrations, ion release measurements, in vitro bioactivity tests, SEM and fluorescence microscopy, and Folin-Ciocalteu and biological tests. The presence of grafted polyphenols as a homogeneous layer was proven. The grafted polyphenols maintained their antioxidant ability and were anchored to the surface through the linking action of Ca²⁺ ions added to the functionalizing solution. Iodine ion release, cytocompatibility towards human mesenchymal stem cells (hMSC), and antibacterial activity were maintained even after functionalization. The antioxidant ability of the functionalized surface was effective in preserving hMSC viability in a chemically induced pro-inflammatory environment, thus showing a scavenger activity towards toxic active species responsible for inflammation.

An In Vitro Engineered Osteochondral Model as Tool to Study Osteoarthritis Environment

Osteoarthritis (OA) is a joint degenerative pathology characterized by mechanical and inflammatory damages affecting synovium, articular cartilage (AC), and subchondral bone (SB). Several in vitro, in vivo, and ex vivo models are developed to study OA, but to date the identification of specific pharmacological targets seems to be hindered by the lack of models with predictive capabilities. This study reports the development of a biomimetic in vitro model of AC and SB interface. Gellan gum methacrylated and chondroitin sulfate/dopamine hydrogels are used for the AC portion, whereas polylactic acid functionalized with gelatin and nanohydroxyapatite for the SB. The physiological behavior of immortalized stem cells (Y201s) and Y201s differentiated in chondrocytes (Y201-Cs), respectively, for the SB and AC, is demonstrated over 21 days of culture in vitro in healthy and pathological conditions, whilst modeling the onset of cytokines-induced OA. The key metrics are: lower glycosaminoglycans production and increased calcification given by a higher Collagen X content, in the AC deep layer; higher expression of pro-angiogenic factor (vegf) and decreased expression of osteogenic markers (coll1, spp1, runx2) in the SB. This novel approach provides a new tool for studying the development and progression of OA.

A bioprintable gellan gum/lignin hydrogel: a smart and sustainable route for cartilage regeneration

In this work a hydrogel, based on a blend of two gellan gums with different acyl content embedding lignin (up to 0.4%w/v) and crosslinked with magnesium ions, was developed for cartilage regeneration. The physico-chemical characterizations established that no chemical interaction between lignin and polysaccharides was detected. Lignin achieved up to 80 % of ascorbic acid's radical scavenging activity in vitro on DPPH and ABTS radicals. Viability of hMSC onto hydrogel containing lignin resulted comparable to the lignin-free one (>70 % viable cells, p > 0.05). The presence of lignin improved the hMSC 3D-constructs chondrogenesis, bringing to a significant (p < 0.05) up-regulation of the collagen type II, aggrecan and SOX 9 chondrogenic genes, and conferred bacteriostatic properties to the hydrogel, reducing the proliferation of S. aureus and S. epidermidis. Finally, cellularized 3D-constructs were manufactured via 3D-bioprinting confirming the processability of the formulation as a bioink and its unique biological features for creating a physiological milieu for cell growth.

Valuable effect of Manuka Honey in increasing the printability and chondrogenic potential of a naturally derived bioink

Hydrogel-based bioinks are the main formulations used for Articular Cartilage (AC) regeneration due to their similarity to chondral tissue in terms of morphological and mechanical properties. However, the main challenge is to design and formulate bioinks able to allow reproducible additive manufacturing and fulfil the biological needs for the required tissue. In our work, we investigated an innovative Manuka honey (MH)-loaded photocurable gellan gum methacrylated (GGMA) bioink, encapsulating mesenchymal stem cells differentiated in chondrocytes (MSCs-C), to generate 3D bioprinted construct for AC studies. We demonstrated the beneficial effect of MH incorporation on the bioink printability, leading to the obtainment of a more homogenous filament extrusion and therefore a better printing resolution. Also, GGMA-MH formulation showed higher viscoelastic properties, presenting complex modulus G∗ values of ∼1042 ​Pa, compared to ∼730 ​Pa of GGMA. Finally, MH-enriched bioink induced a higher expression of chondrogenic markers col2a1 (14-fold), sox9 (3-fold) and acan (4-fold) and AC ECM main element production (proteoglycans and collagen).

"Green" Biomaterials: The Promising Role of Honey

The development of nanotechnology has allowed us to better exploit the potential of many natural compounds. However, the classic nanotechnology approach often uses both dangerous and environmentally harmful chemical compounds and drastic conditions for synthesis. Nevertheless, “green chemistry” techniques are revolutionizing the possibility of making technology, also for tissue engineering, environmentally friendly and cost-effective. Among the many approaches proposed and among several natural compounds proposed, honey seems to be a very promising way to realize this new “green” approach.

Controlled release of resveratrol from a composite nanofibrous scaffold: Effect of resveratrol on antioxidant activity and osteogenic differentiation

Biocompatibility, mechanical strength, and osteogenesis properties of three-dimensional scaffolds are critical for bone tissue engineering. In addition, reactive oxygen species accumulate around bone defects and limit the activities of surrounding cells and bone formation. Therefore, the presence of an antioxidant in a bone tissue scaffold is also essential to address this issue. This study aimed to evaluate a composite nanofibrous scaffold similar to the natural extracellular matrix with antioxidant and osteogenic properties. To this end, polylactic acid (PLA)/organophilic montmorillonite (OMMT)/resveratrol (RSV) nanofibers were fabricated using the electrospinning method and characterized. RSV was used as an antioxidant, which promotes osteogenic differentiation, and OMMT was used as a mineral phase to increase the mechanical strength and control the release of RSV. The scaffolds' antioxidant activity was measured using DPPH assay and found 83.75% for PLA/OMMT/RSV nanofibers. The mechanical strength was increased by adding OMMT to the neat PLA. The biocompatibility of the scaffolds was investigated using an MTT assay, and the results did not show any toxic effects on human adipose mesenchymal stem cells (hASCs). Moreover, the Live/Dead assay indicated the appropriate distribution of live cells after 5 days. Cell culture results displayed that hASCs could adhere and spread on the surface of composite nanofibers. Meanwhile, the level of alkaline phosphatase, osteocalcin, and osteopontin was increased for hASCs cultured on the PLA/OMMT/RSV nanofibrous scaffold. Therefore, this study concludes that the RSV-loaded composite nanofibers with antioxidant and osteogenesis properties and appropriate mechanical strength can be introduced for bone tissue regeneration applications.

The Potential of Honeybee Products for Biomaterial Applications

The development of biomaterials required continuous improvements in their properties for new tissue engineering applications. Implants based on biocompatible materials and biomaterial-based dressings are susceptible to infection threat; moreover, target tissues can suffer injuring inflammation. The inclusion of nature-derived bioactive compounds usually offers a suitable strategy to expand or increase the functional properties of biomaterial scaffolds and can even promote tissue healing. Honey is traditionally known for its healing property and is a mixture of phytochemicals that have a proven reputation as antimicrobial, anti-inflammatory, and antioxidant agents. This review discusses on the potential of honey and other honeybee products for biomaterial improvements. Our study illustrates the available and most recent literature reporting the use of these natural products combined with different polymeric scaffolds, to provide original insights in wound healing and other tissue regenerative approaches.