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Hyaluronic acid (HA) is a natural polymer, produced endogenously by the human body, which has unique physicochemical and biological properties, exhibiting desirable biocompatibility and biodegradability. Therefore, it has been widely studied for possible applications in the area of inflammatory diseases. Although exogenous HA has been described as unable to restore or replace the properties and activities of endogenous HA, it can still provide satisfactory pain relief. This review aims to discuss the advances that have been achieved in the treatment of inflammatory diseases using hyaluronic acid as a key ingredient, essentially focusing on studies carried out between the years 2017 and 2021.

The discovery of several unexpected complex biological roles of hyaluronic acid (HA) has promoted new research impetus for biologists and, the clinical interest in several fields of medicine, such as ophthalmology, articular pathologies, cutaneous repair, skin remodeling, vascular prosthesis, adipose tissue engineering, nerve reconstruction and cancer therapy. In addition, the great potential of HA in medicine has stimulated the interest of pharmaceutical companies which, by means of new technologies can produce HA and several new derivatives in order to increase both the residence time in a variety of human tissues and the anti-inflammatory properties. Minor chemical modifications of the molecule, such as the esterification with benzyl alcohol (Hyaff-11® biomaterials), have made possible the production of water-insoluble polymers that have been manufactured in various forms: membranes, gauzes, nonwoven meshes, gels, tubes. All these biomaterials are used as wound-covering, anti-adhesive devices and as scaffolds for tissue engineering, such as epidermis, dermis, micro-vascularized skin, cartilage and bone. In this review, the essential biological functions of HA and the applications of its derivatives for pharmaceutical and tissue regeneration purposes are reviewed.

Naked mole-rat (NMR), the longest-living rodent, produces very-high-molecular-mass hyaluronan (vHMM-HA), compared to other mammalian species. However, it is unclear if exceptional polymer length of vHMM-HA is important for longevity. Here, we show that vHMM-HA (>6.1 MDa) has superior cytoprotective properties compared to the shorter HMM-HA. It protects not only NMR cells, but also mouse and human cells from stress-induced cell-cycle arrest and cell death in a polymer length-dependent manner. The cytoprotective effect is dependent on the major HA-receptor, CD44. We find that vHMM-HA suppresses CD44 protein-protein interactions, whereas HMM-HA promotes them. As a result, vHMM-HA and HMM-HA induce opposing effects on the expression of CD44-dependent genes, which are associated with the p53 pathway. Concomitantly, vHMM-HA partially attenuates p53 and protects cells from stress in a p53-dependent manner. Our results implicate vHMM-HA in anti-aging mechanisms and suggest the potential applications of vHMM-HA for enhancing cellular stress resistance. Naked mole rats are the longest-lived rodents and produce very-high-molecular-mass hyaluronan (vHMM-HA). Here the authors show that naked mole rat vHMM-HA is better at protecting mouse and human cells from cell cycle arrest and cell death, compared to the high-molecular-mass hyaluronan produced by these species.

In bone regenerative medicine there is a need for suitable bone substitutes. Hydrogels have excellent biocompatible and biodegradable characteristics, but their visco-elastic properties limit their applicability, especially with respect to 3D bioprinting. In this study, we modified the naturally occurring extracellular matrix glycosaminoglycan hyaluronic acid (HA), in order to yield photo-crosslinkable hydrogels with increased mechanical stiffness and long-term stability, and with minimal decrease in cytocompatibility. Application of these tailor-made methacrylated hyaluronic acid (MeHA) gels for bone tissue engineering and 3D bioprinting was the subject of investigation. Visco-elastic properties of MeHA gels, measured by rheology and dynamic mechanical analysis, showed that irradiation of the hydrogels with UV light led to increased storage moduli and elastic moduli, indicating increasing gel rigidity. Subsequently, human bone marrow derived mesenchymal stromal cells (MSCs) were incorporated into MeHA hydrogels, and cell viability remained 64.4% after 21 days of culture. Osteogenic differentiation of MSCs occurred spontaneously in hydrogels with high concentrations of MeHA polymer, in absence of additional osteogenic stimuli. Addition of bone morphogenetic protein-2 (BMP-2) to the culture medium further increased osteogenic differentiation, as evidenced by increased matrix mineralisation. MeHA hydrogels demonstrated to be suitable for 3D bioprinting, and were printed into porous and anatomically shaped scaffolds. Taken together, photosensitive MeHA-based hydrogels fulfilled our criteria for cellular bioprinted bone constructs within a narrow window of concentration.

ABSTRACT Background The selection of dermal fillers in aesthetic medicine often relies on factors such as cost, immediate outcomes, and practitioner experience. However, incorporating knowledge of fillers' rheological properties, such as viscoelasticity and cohesiveness, allows for more precise product selection tailored to patient needs and treatment goals while reducing the risk of complications. Aims This review aims to summarize essential considerations for filler selection, focusing on rheological properties, safety profiles, and clinical applications. Additionally, it seeks to highlight differences between hyaluronic acid (HA) fillers and non‐HA fillers to guide practitioners in aesthetic procedures. Patients/Methods A systematic review was conducted following PRISMA guidelines. Searches across PubMed, Scopus, Web of Science, and the Cochrane Library yielded 619 articles. After duplicate removal and rigorous screening, 50 peer‐reviewed studies were included. Data extraction focused on filler types, rheological properties (e.g., G′ and G″ values), safety, and efficacy. Results HA fillers, particularly monophasic types, exhibit smoother consistency and better cohesiveness, making them ideal for high‐mobility areas like the mouth. Biphasic fillers, with higher viscoelasticity, provide superior lifting capacity for deeper tissue support. Non‐HA fillers, such as poly‐L‐lactic acid and calcium hydroxylapatite, offer longer‐lasting results but require precise techniques due to irreversibility. Proper selection based on filler rheology, target area, and patient needs can mitigate risks such as overfilled syndrome, Tyndall effect, and delayed inflammatory responses. Conclusions Understanding the rheological and safety profiles of fillers is essential for achieving optimal aesthetic outcomes. HA fillers are recommended for novice practitioners due to their reversibility, while experienced clinicians may explore non‐HA options. Tailored filler selection based on rheological properties and clinical context ensures safer and more effective treatments.

This study proposes a review on hyaluronic acid (HA) known as hyaluronan or hyaluronate and its derivates and their application in cosmetic formulations. HA is a glycosaminoglycan constituted from two disaccharides (N-acetylglucosamine and D-glucuronic acid), isolated initially from the vitreous humour of the eye, and subsequently discovered in different tissues or fluids (especially in the articular cartilage and the synovial fluid). It is ubiquitous in vertebrates, including humans, and it is involved in diverse biological processes, such as cell differentiation, embryological development, inflammation, wound healing, etc. HA has many qualities that recommend it over other substances used in skin regeneration, with moisturizing and anti-ageing effects. HA molecular weight influences its penetration into the skin and its biological activity. Considering that, nowadays, hyaluronic acid has a wide use and a multitude of applications (in ophthalmology, arthrology, pneumology, rhinology, aesthetic medicine, oncology, nutrition, and cosmetics), the present study describes the main aspects related to its use in cosmetology. The biological effect of HA on the skin level and its potential adverse effects are discussed. Some available cosmetic products containing HA have been identified from the brand portfolio of most known manufacturers and their composition was evaluated. Further, additional biological effects due to the other active ingredients (plant extracts, vitamins, amino acids, peptides, proteins, saccharides, probiotics, etc.) are presented, as well as a description of their possible toxic effects.

The biological complexity of sarcopenia presents a major challenge for therapeutic intervention due to the wide range of degenerative changes it induces in skeletal muscle. This study demonstrates the potential of liposomal controlled release systems to address these challenges by combining two bioactive agents with complementary actions: caffeine (CAF), encapsulated in DMPC-based liposomes, and hyaluronic acid methacrylate (HAMA), encapsulated in DOPC-based liposomes. A hybrid system was also developed to deliver both substances simultaneously, aiming to restore tissue function through combined metabolic, anti-inflammatory, and regenerative effects. The liposomes exhibited nanoscale dimensions, spherical morphology, and intact membrane structure, as confirmed by electron microscopy. DLS analysis indicated good colloidal stability and monodisperse size distribution across all formulations, with improved stability observed in the hybrid system. Drug release studies showed a time-dependent profile, with HAMA releasing rapidly and CAF releasing gradually, supporting a dual-action therapeutic approach tailored to the multifactorial pathology of sarcopenia. The biological assays, performed in an established in vitro sarcopenia model, revealed the potential of liposomes co-delivering caffeine and HAMA to mitigate oxidative stress, preserve mitochondrial function, and reduce apoptosis in H2O2-damaged myotubes.

Hyaluronic acid (HA) is a linear heteropolysaccharide that naturally occurs in vertebrates. Thanks to its unique physico-chemical properties, it is involved in many key processes in living organisms. These biological activities provide the basis for its broad applications in cosmetics, medicine, and the food industry. The molecular weight of HA might vary significantly, as it can be less than 10 kDa or reach more than 6000 kDa. There is a strong correlation between variations in its molecular weight and bioactivities, as well as with various pathological processes. Consequently, monodispersity is a crucial requirement for HA production, together with purity and safety. Common industrial approaches, such as extraction from animal sources and microbial fermentation, have limits in fulfilling these requests. Research and protein engineering with hyaluronic acid synthases can provide a strong tool for the production of monodisperse HA. One-pot multi-enzyme reactions that include in situ nucleotide phosphate regeneration systems might represent the future of HA production. In this review, we explore the current knowledge about HA, its production, hyaluronic synthases, the most recent stage of in vitro enzymatic synthesis research, and one-pot approaches.

Background Psoriasis vulgaris is the most common form of psoriasis, yet current treatments often lead to significant side effects, resulting in a high rate of therapy desertion. Here, we explored a novel therapeutic approach using the secretome from Wharton Jelly-derived mesenchymal stem cells, biologically stabilized and enhanced with hyaluronic acid (HA), its presentation is an easy-to-apply topical sponge. This formulation had previously demonstrated efficacy in vitro and in experimental psoriasis mouse models. Methods In vitro characterization studies included dynamic light scattering, nanoparticle tracking analysis, optical/electronic microscopy, microbiological experiments, and angiogenic capacity (HUVEC cells). In vivo studies included angiogenic capacity in chicken embryo chorioallantoic membrane (CAM), safety (hypersensitive and healthy volunteers), and efficacy (double-blinded and randomized patients). Results We demonstrated the presence of spherical exosomes (164 ± 87 nm, PDI of 0.38, and 1.5 × 10⁷ particles/mL) within the selected secretomes, which exhibited significant proangiogenic activity in HUVEC cells and in a CAM assay. The secretome-containing sponges displayed distinct physicochemical properties, such as the absence of nitrogen and reduced carbon and oxygen content, resulting in a more cross-linked material with thinner fibers. These characteristics extended the dispersion time in aqueous media. Microbiological testing confirmed sterility in the packed, ready-to-use secretome-HA sponges after 3 months of storage. To assess safety, we selected doses (based on total protein content) that were applied to three patients with atopic dermatitis (42 µg of protein, patch test, 5 days) and four healthy volunteers (210 µg, 15 days) with no observed adverse topical or systemic effects. In a 30-day efficacy study, 12 patients with bilateral psoriasis exhibited up to a 33% reduction in mPASI scores and a 41% decrease in plaque size. Additionally, transepidermal water loss (TEWL) was reduced by up to 30%, while skin elasticity/flexibility improved by 43%. Conclusions These findings suggest that the topical application of the secretome-HA sponge is a safe and effective therapeutic option for alleviating symptoms of psoriasis vulgaris . Trial registration SSMN, SSMN047/2021. Registered 27 October 2021, https://www.ssmn.cl/comite_etica.php . Graphical abstract

A glucose-responsive “closed-loop” insulin delivery system mimicking the function of pancreatic cells has tremendous potential to improve quality of life and health in diabetics. Here, we report a novel glucose-responsive insulin delivery device using a painless microneedle-array patch (“smart insulin patch”) containing glucose-responsive vesicles (GRVs; with an average diameter of 118 nm), which are loaded with insulin and glucose oxidase (GO ₓ) enzyme. The GRVs are self-assembled from hypoxia-sensitive hyaluronic acid (HS-HA) conjugated with 2-nitroimidazole (NI), a hydrophobic component that can be converted to hydrophilic 2-aminoimidazoles through bioreduction under hypoxic conditions. The local hypoxic microenvironment caused by the enzymatic oxidation of glucose in the hyperglycemic state promotes the reduction of HS-HA, which rapidly triggers the dissociation of vesicles and subsequent release of insulin. The smart insulin patch effectively regulated the blood glucose in a mouse model of chemically induced type 1 diabetes. The described work is the first demonstration, to our knowledge, of a synthetic glucose-responsive device using a hypoxia trigger for regulation of insulin release. The faster responsiveness of this approach holds promise in avoiding hyperglycemia and hypoglycemia if translated for human therapy.