Experimental approaches to hyaluronan structure

Polymers and their engineered analogues for ocular drug delivery: Enhancing therapeutic precision

Ocular drug delivery is constrained by anatomical and physiological barriers, necessitating innovative solutions for effective therapy. Natural polymers like hyaluronic acid, chitosan, and gelatin, alongside synthetic counterparts such as PLGA and PEG, have gained prominence for their biocompatibility and controlled release profiles. Recent strides in polymer conjugation strategies have enabled targeted delivery through ligand integration, facilitating tissue specificity and cellular uptake. This versatility accommodates combined drug delivery, addressing diverse anterior (e.g., glaucoma, dry eye) and posterior segment (e.g., macular degeneration, diabetic retinopathy) afflictions. The review encompasses an in-depth exploration of each natural and synthetic polymer, detailing their individual advantages and disadvantages for ocular drug delivery. By transcending ocular barriers and refining therapeutic precision, these innovations promise to reshape the management of anterior and posterior segment eye diseases.

A microscale 3D organ on a chip for recapitulating reciprocal neuroendocrine crosstalk between the hypothalamus and the pituitary gland

Conventional 2D or even recently developed 3Din vitroculture models for hypothalamus and pituitary gland cannot successfully recapitulate reciprocal neuroendocrine communications between these two pivotal neuroendocrine tissues known to play an essential role in controlling the body's endocrine system, survival, and reproduction. In addition, most currentvitroculture models for neuroendocrine tissues fail to properly reflect their complex multicellular structure. In this context, we developed a novel microscale chip platform, termed the 'hypothalamic-pituitary (HP) axis-on-a-chip,' which integrates various cellular components of the hypothalamus and pituitary gland with biomaterials such as collagen and hyaluronic acid. We used non-toxic blood coagulation factors (fibrinogen and thrombin) as natural cross-linking agents to increase the mechanical strength of biomaterials without showing residual toxicity to overcome drawbacks of conventional chemical cross-linking agents. Furthermore, we identified and verified SERPINB2 as a reliable neuroendocrine toxic marker, with its expression significantly increased in both hypothalamus and pituitary gland cells following exposure to various types of toxins. Next, we introduced SERPINB2-fluorescence reporter system into loaded hypothalamic cells and pituitary gland cells within each chamber of the HP axis on a chip, respectively. By incorporating this SERPINB2 detection system into the loaded hypothalamic and pituitary gland cells within our chip platform, Our HP axis-on-chip platform can better mimic reciprocal neuroendocrine crosstalk between the hypothalamus and the pituitary gland in the brain microenvironments with improved efficiency in evaluating neuroendocrine toxicities of certain drug candidates.

Clinical and Biochemical Implications of Hyaluronic Acid in Musculoskeletal Rehabilitation: A Comprehensive Review

Hyaluronic acid (HA) naturally occurs as a biopolymer in the human body, primarily in connective tissues like joints and skin. Functioning as a vital element of synovial fluid, it lubricates joints, facilitating fluid movement and diminishing bone friction to protect articular well-being. Its distinctive attributes encompass notable viscosity and water retention capacities, ensuring flexibility and absorbing shock during motion. Furthermore, HA has gained significant attention for its potential benefits in various medical applications, including rehabilitation. Ongoing research explores its properties and functions, especially its biomedical applications in several clinical trials, with a focus on its role in improving rehabilitation outcomes. But the clinical and biochemical implications of HA in musculoskeletal rehabilitation have yet to be fully explored. This review thoroughly investigates the properties and functions of HA while highlighting its biomedical applications in different clinical trials, with a special emphasis on its role in rehabilitation. The presented findings provide evidence that HA, as a natural substance, enhances the outcomes of musculoskeletal rehabilitation through its exceptional mechanical and biochemical effects.

Hyaluronic acid single-network hydrogel with high stretchable and elastic properties

Stretchable materials have demonstrated great interest in wearable or implantable applications. Most of the existing hydrogels with high stretchability characteristics are based on double networks, exhibit large hysteresis loops, and cannot recover after deformation due to permanent rupture of network. Elastic, biodegradable, and biocompatible hydrogels are desirable for wound dressing of joints with frequent motions or post-surgical healing of mobile tissues. Here, we show a simple strategy for the preparation of a hyaluronic acid (HA) single-network hydrogel that can be stretchable and highly elastic without the addition of other components/partners or complicated processes of preparation. Our strategy relies on the use of high Mw HA to create a chemical hydrogel in which densely entangled HA chains are tied together by a small number of covalent bonds. While the presence of covalent cross-links can prevent disintegration of the HA network, entanglements endow the hydrogel with high stretchability through transmission of tension along the length of the long HA chains. The stretching-relaxation cycles show negligible hysteresis and perfect recovery of material after the release of force. The diminution of Mw together with increasing the concentration or cross-linker amount leads to brittle hydrogels.

Hyaluronic acid: More than a carrier, having an overpowering extracellular and intracellular impact on cancer

Hyaluronic acid (HA), also named hyaluronan, is an omnipresent component of the tissue microenvironment. It is extensively used to formulate targeted drug delivery systems for cancer. Although HA itself has pivotal influences in various cancers, its calibers are somewhat neglected when using it as delivering platform to treat cancer. In the last decade, multiple studies revealed roles of HA in cancer cell proliferation, invasion, apoptosis, and dormancy through pathways like mitogen-activated protein kinase-extracellular signal-regulated kinase (MAPK/ERK), P³⁸, and nuclear factor kappa-light chain-enhancer of activated B cells (NFκB). A more fascinating fact is that the distinct molecular weight (MW) of HA exerts disparate effects on the same type of cancer. Its overwhelming use in cancer therapy and other therapeutic products make collective research on the sundry impact of it on various types of cancer, an essential aspect to be considered in all of these domains. Even the development of new therapies against cancer needed meticulous studies on HA because of its divergence of activity based on MW. This review will provide painstaking insight into the extracellular and intracellular bioactivity of HA, its modified forms, and its MW in cancers, which may improve the management of cancer.

Innovative Design of Targeted Nanoparticles: Polymer-Drug Conjugates for Enhanced Cancer Therapy

Polymer-drug conjugates (PDCs) have shown great promise in enhancing the efficacy and safety of cancer therapy. These conjugates combine the advantageous properties of both polymers and drugs, leading to improved pharmacokinetics, controlled drug release, and targeted delivery to tumor tissues. This review provides a comprehensive overview of recent developments in PDCs for cancer therapy. First, various types of polymers used in these conjugates are discussed, including synthetic polymers, such as poly(↋-caprolactone) (PCL), D-α-tocopheryl polyethylene glycol (TPGS), and polyethylene glycol (PEG), as well as natural polymers such as hyaluronic acid (HA). The choice of polymer is crucial to achieving desired properties, such as stability, biocompatibility, and controlled drug release. Subsequently, the strategies for conjugating drugs to polymers are explored, including covalent bonding, which enables a stable linkage between the polymer and the drug, ensuring controlled release and minimizing premature drug release. The use of polymers can extend the circulation time of the drug, facilitating enhanced accumulation within tumor tissues through the enhanced permeability and retention (EPR) effect. This, in turn, results in improved drug efficacy and reduced systemic toxicity. Moreover, the importance of tumor-targeting ligands in PDCs is highlighted. Various ligands, such as antibodies, peptides, aptamers, folic acid, herceptin, and HA, can be incorporated into conjugates to selectively deliver the drug to tumor cells, reducing off-target effects and improving therapeutic outcomes. In conclusion, PDCs have emerged as a versatile and effective approach to cancer therapy. Their ability to combine the advantages of polymers and drugs offers enhanced drug delivery, controlled release, and targeted treatment, thereby improving the overall efficacy and safety of cancer therapies. Further research and development in this field has great potential to advance personalized cancer treatment options.

Hyaluronic Acid-Based Bioconjugate Systems, Scaffolds, and Their Therapeutic Potential

In recent years, the development of hyaluronic acid or hyaluronan (HA) based scaffolds, medical devices, bioconjugate systems have expanded into a broad range of research and clinical applications. Research findings over the last two decades suggest that the abundance of HA in most mammalian tissues with distinctive biological roles and chemical simplicity for modifications have made it an attractive material with a rapidly growing global market. Besides its use as native forms, HA has received much interest on so-called "HA-bioconjugates" and "modified-HA systems". In this review, the importance of chemical modifications of HA, underlying rationale approaches, and various advancements of bioconjugate derivatives with their potential physicochemical, and pharmacological advantages are summarized. This review also highlights the current and emerging HA-based conjugates of small molecules, macromolecules, crosslinked systems, and surface coating strategies with their biological implications, including their potentials and key challenges discussed in detail.

Analyzing the Quality and Readability of Online Hyaluronic Acid Knee Injection Resources

INTRODUCTION

We analyzed the quality of information about Hyaluronic acid (HA) knee injections for osteoarthritis using DISCERN, a tool that grades the quality of websites. We also analyzed readability with Flesch-Kincaid grade reading levels (FKGRL).

METHODS

Lists of the top ten included sites from Google searches about HA injections were evaluated using DISCERN to determine their quality. Additional variables collected were site category, Health on Net (HON) certification, search result rank, and FKGRL. DISCERN scores were compared and grouped by these variables.

RESULTS

Most sites were measured as fair in quality. Greater DISCERN scores were produced from searches using general terminology, sites with HON labels, and academic journal publications.

CONCLUSION

This study indicates information quality for HA injections online is fair. The data also indicates that patients can best educate themselves using HON labels, general search terms, and information from academic journals when possible.

Molecular insights of anti-diabetic compounds and its hyaluronic acid conjugates against aldose reductase enzyme through molecular modeling and simulations study-a novel treatment option for inflammatory diabetes

CONTEXT

Chronic inflammation is a risk factor for diabetes, but it can also be a complication of diabetes, leading to severe diabetes and causing many other clinical manifestations. Inflammation is a major emerging complication in both type I and type II diabetes, which causes increasing interest in targeting inflammation to improve and control diabetes. Diabetes with insulin resistance and impaired glucose utilization in humans and their underlying mechanism is not fully understood. But a growing understanding of the intricacy of the insulin signaling cascade in diabetic inflammatory cells reveals potential target genes and their proteins responsible for severe insulin resistance. With this baseline concept, the current project explores the binding affinities of the hyaluronic acid anti-diabetic compounds conjugates to such target proteins in diabetic inflammatory cells and their molecular geometries. A range of 48 anti-diabetic compounds was screened against aldose reductase binding pocket 3 protein target through in silico molecular docking, and results revealed that three compounds viz, metformin (CID:4091), phenformin (CID:8249), sitagliptin (CID:4,369,359), possess significant binding affinity out of 48 chosen drugs. Further, these three anti-diabetic compounds were conjugated with hyaluronic acid (HA), and their binding affinity and their molecular geometrics towards aldose reductase enzyme were screened compared with the free form of the drug. The molecular geometries of three shortlisted drugs (metformin, phenformin, sitagliptin) and their HA conjugates were also explored through density functional theory studies, and it proves their good molecular geometry towards pocket 3 of aldose reductase target. Further, MD simulation trajectories affirm that HA conjugates possess good binding affinity and simulation trajectories with protein target aldose reductase than a free form of the drug. Our current study unravels the new mechanism of drug targeting for diabetes through HA conjugation for inflammatory diabetes. HA conjugates act as novel drug candidates for treating inflammatory diabetes; however, it needs further human clinical trials.

METHODS

For ligand structure, PubChem, ACD chem sketch, and online structure file generator platform are utilized for ligand preparation. Target protein aldose reductase obtained from protein database (PDB). For molecular docking analysis, AutoDock Vina (Version 4) was utilized. pKCSM online server used to predict ADMET properties of the above three shortlisted drugs from the docking study. Using mol-inspiration software (version 2011.06), three shortlisted compounds' bioactivity scores were predicted. DFT analysis for three shortlisted anti-diabetic drugs and their hyaluronic acid conjugates were calculated using a functional B3LYP set of Gaussian 09 software. Molecular dynamics simulation calculations for six chosen protein-ligand complexes were done through YASARA dynamics software and AMBER14 force field.

The value of injectable viscoelastic supplements for joints

Intra-articular viscoelastic supplements are commonly administered by musculoskeletal radiologists for the treatment of symptomatic osteoarthritis (OA). This article provides an overview of the putative mechanism of action of the agents, a brief review of the evidence base underlying the practice, a commentary on some of the major society guidelines regarding the treatment, and a description of the adverse events that are associated with intra-articular hyaluronic acid administration.

Biocompatible Macroion/Growth Factor Assemblies for Medical Applications

Growth factors are a class of proteins that play a role in the proliferation (the increase in the number of cells resulting from cell division) and differentiation (when a cell undergoes changes in gene expression becoming a more specific type of cell) of cells. They can have both positive (accelerating the normal healing process) and negative effects (causing cancer) on disease progression and have potential applications in gene therapy and wound healing. However, their short half-life, low stability, and susceptibility to degradation by enzymes at body temperature make them easily degradable in vivo. To improve their effectiveness and stability, growth factors require carriers for delivery that protect them from heat, pH changes, and proteolysis. These carriers should also be able to deliver the growth factors to their intended destination. This review focuses on the current scientific literature concerning the physicochemical properties (such as biocompatibility, high affinity for binding growth factors, improved bioactivity and stability of the growth factors, protection from heat, pH changes or appropriate electric charge for growth factor attachment via electrostatic interactions) of macroions, growth factors, and macroion-growth factor assemblies, as well as their potential uses in medicine (e.g., diabetic wound healing, tissue regeneration, and cancer therapy). Specific attention is given to three types of growth factors: vascular endothelial growth factors, human fibroblast growth factors, and neurotrophins, as well as selected biocompatible synthetic macroions (obtained through standard polymerization techniques) and polysaccharides (natural macroions composed of repeating monomeric units of monosaccharides). Understanding the mechanisms by which growth factors bind to potential carriers could lead to more effective delivery methods for these proteins, which are of significant interest in the diagnosis and treatment of neurodegenerative and civilization diseases, as well as in the healing of chronic wounds.

Interactions between Sodium Hyaluronate and β-Cyclodextrin as Seen by Transport Properties

Knowledge of mass transport parameters, diffusion, and viscosity of hyaluronic acid (HA) in the presence of cyclodextrins is of considerable importance for areas such as food packaging and drug delivery, among others. Despite a number of studies investigating the functionalization of HA or the corresponding sodium salt by cyclodextrins, only a few studies have reported the effect of cyclodextrins on the mass transport of HA in the presence of these oligosaccharides. Here, we report the tracer binary and ternary interdiffusion coefficients of sodium hyaluronate (NaHy) in water and aqueous β-cyclodextrin solutions. The diffusion behavior of sodium hyaluronate was dependent on the reduced viscosity of NaHy, which, in turn, presented a concave dependence on concentration, with a minimum at approximately 2.5 g dm^-3. The significant decrease in the limiting diffusion coefficient of NaHy (at most 45%) at NaHy concentrations below 1 g dm^-3 in the presence of β-cyclodextrin, taking water as the reference, allowed us to conclude that NaHy strongly interacted with the cyclodextrin.

Comparative clinical study for the efficacy and safety of two different hyaluronic acid-based fillers with Tri-Hyal versus Vycross technology: A long-term prospective randomized clinical trial

BACKGROUND

Hyaluronic acid-based fillers have an immediate volumizing effect for the treatment of dermal contour deformities and to smooth dermal depressions formed by the loss of volume. A previous study on 2016-2018 has shown the efficacy and safety of the HA-based filler ART FILLER® Volume on the midface only, but not in a comparative manner.

METHODS

In this context, an 18 months prospective randomized single-blind study of the non-inferiority of ART FILLER® Volume versus the reference product Juvéderm Voluma® was performed on the midface, temple, and jawline, and non-comparative study on the chin. The efficacy and the longevity were evaluated for the selected face areas via dedicated clinical scoring systems after a single filler injection without any re-touch or re-injection. The short- and long-term adverse effects were also recorded.

RESULTS

The observations confirmed the non-inferiority of ART FILLER® Volume versus the reference product on the different injected areas. For both fillers, the beneficial effects on volumes restoration were maintained 18 months post-injection; however, these effects were diminished among the time. Furthermore, injections of Art Filler® Volume were well tolerated by the subjects and showed less acute side effects compared with the reference product that may be explained by a lower induction of inflammation.

Synthesis, characterization and evaluation of hyaluronic acid-based polymers for nasal delivery

Epidemiological research has found that between 5 and 12 percent of the population suffers from chronic rhinosinusitis. Patients are dealing with local side effects such as nasal dryness, sporadic sneezing, and nasal pain in addition to the inflammation. The aim of this study was to synthesize a polymer based on hyaluronic acid in order to provide lubrication combined with a ligand leading to a covalent binding on the nasal mucosa. Hyaluronic acid (HA) was modified with L-cysteine ethyl ester hydrochloride (CYS) via amid bond formation. Ellman's assay, together with spectroscopic techniques like IR and ¹H NMR, confirmed that HACys had been successfully synthesized. It was demonstrated that HACys is safe for administration on the nasal mucosa. The mucoadhesive potential was determined by 3.26-fold with the rotating cylinder assay and 1.4-fold in terms of bioadhesive examination, respectively. Further, the stability of the modified polymer was improved by 7.6-fold compared to the unmodified polymer. Spraying the formulation on the nasal mucosa, the residence time of a model drug was 1.74-fold prolonged at the site of action compared to unmodified polymer. In light of these findings, modified hyaluronic acid (HACys) displayed compelling properties such as lubricity, targeted application, long-lasting effect, and safety and therefore could be an excellent candidate for nasal application.

The Influence of a Single Instrument-Assisted Manual Therapy (IAMT) for the Lower Back on the Structural and Functional Properties of the Dorsal Myofascial Chain in Female Soccer Players: A Randomised, Placebo-Controlled Trial

Background: Instrument-assisted manual therapy (IAMT) is indicated to improve flexibility, reduce pain, and induce hyperaemia locally and along myofascial chains. The underlying effects are largely unclear. This randomised, placebo-controlled pilot study aimed to gain first insights into these effects, primarily on the structural level, through ultrasonography. Methods: 67 healthy female soccer players aged 20.9 (±3.9) years were examined after right lumbar intervention (IAMT: intervention group (IG), heat application: comparison group (CG), pressure-less placebo: placebo group (PG)). Ultrasonography (absolute movement and shear motion), flexibility tests (passive straight leg raise test (PSLR), lumbar and thoracic double inclinometry), and superficial skin temperature were recorded before (t0), immediately (t1) and 45 min after the intervention (t2). Results: IAMT decreased the absolute mobility of the superficial lamina and its shear motion to the superficial fascia compared with the PG (t1; p < 0.05). PSLR improved in the IG compared with the CG (t2) and PG (t1, t2; p < 0.05). The temperature increased in the IG and CG compared with the PG (t1, t2) and in the CG compared with the IG (t1; p < 0.05). Conclusion: IAMT of the lumbar back briefly reduces absolute mobility of the superficial lamina and its shear motion to the superficial fascia, improves flexibility, and increases the temperature.

Noncovalent hyaluronan crosslinking by TSG-6: Modulation by heparin, heparan sulfate, and PRG4

The size, conformation, and organization of the glycosaminoglycan hyaluronan (HA) affect its interactions with soluble and cell surface-bound proteins. HA that is induced to form stable networks has unique biological properties relative to unmodified soluble HA. AlphaLISA assay technology offers a facile and general experimental approach to assay protein-mediated networking of HA in solution. Connections formed between two end-biotinylated 50 kDa HA (bHA) chains can be detected by signal arising from streptavidin-coated donor and acceptor beads being brought into close proximity when the bHA chains are bridged by proteins. We observed that incubation of bHA with the protein TSG-6 (tumor necrosis factor alpha stimulated gene/protein 6, TNFAIP/TSG-6) leads to dimerization or higher order multimerization of HA chains in solution. We compared two different heparin (HP) samples and two heparan sulfate (HS) samples for the ability to disrupt HA crosslinking by TSG-6. Both HP samples had approximately three sulfates per disaccharide, and both were effective in inhibiting HA crosslinking by TSG-6. HS with a relatively high degree of sulfation (1.75 per disaccharide) also inhibited TSG-6 mediated HA networking, while HS with a lower degree of sulfation (0.75 per disaccharide) was less effective. We further identified Proteoglycan 4 (PRG4, lubricin) as a TSG-6 ligand, and found it to inhibit TSG-6-mediated HA crosslinking. The effects of HP, HS, and PRG4 on HA crosslinking by TSG-6 were shown to be due to HP/HS/PRG4 inhibition of HA binding to the Link domain of TSG-6. Using the AlphaLISA platform, we also tested other HA-binding proteins for ability to create HA networks. The G1 domain of versican (VG1) effectively networked bHA in solution but required a higher concentration than TSG-6. Cartilage link protein (HAPLN1) and the HA binding protein segment of aggrecan (HABP, G1-IGD-G2) showed only low and variable magnitude HA networking effects. This study unambiguously demonstrates HA crosslinking in solution by TSG-6 and VG1 proteins, and establishes PRG4, HP and highly sulfated HS as modulators of TSG-6 mediated HA crosslinking.

Hyaluronan Brush-like Copolymers Promote CD44 Declustering in Breast Cancer Cells

We report on the synthesis of hyaluronan (HA) brush-like copolymers and their application as antagonists of tumorigenic CD44-HA interactions. HA (4.8 kDa, ca. 24 saccharides) was grafted on 2-hydrohyethyl methacrylate (HEMA) by end-on oxime ligation. The obtained copolymers were compared with low and high molecular weight HA in terms of hydrolysis kinetics in the presence of hyaluronidase (isothermal titration calorimetry) and interactions with CD44 (surface plasmon resonance). The results evidenced that the high molecular weight HA and HA-g-HEMA have a much higher affinity to CD44 than low molecular weight HA. Additionally, slower enzymatic degradation was observed for the copolymer, making it an excellent candidate for active targeting of tumorigenic CD44-HA interactions. We, therefore, investigated the effect of the copolymer on cancer cell lines with different expression of CD44 and observed an efficient declustering of CD44 that is usually associated with reduction of metastasis and drug resistance.

A Mechanoelastic Glimpse on Hyaluronan-Coated Extracellular Vesicles

Cancer cells secrete extracellular vesicles (EVs) covered with a carbohydrate polymer, hyaluronan (HA), linked to tumor malignancy. Herein, we have unravelled the contour lengths of HA on a single cancer cell-derived EV surface using single-molecule force spectroscopy (SMFS), which divulges the presence of low molecular weight HA (LMW-HA < 200 kDa). We also discovered that these LMW-HA-EVs are significantly more elastic than the normal cell-derived EVs. This intrinsic elasticity of cancer EVs could be directly allied to the LMW-HA abundance and associated labile water network on EV surface as revealed by correlative SMFS, hydration dynamics with fluorescence spectroscopy, and molecular dynamics simulations. This method emerges as a molecular biosensor of the cancer microenvironment.

Selective isolation of hyaluronan by solid phase adsorption to silica

A solid phase adsorption method for selective isolation of hyaluronan (HA) from biological samples is presented. Following enzymatic degradation of protein, HA can be separated from sulfated glycosaminoglycans, other unsulfated glycosaminoglycans, nucleic acids, and proteolytic fragments by adsorption to amorphous silica at specific salt concentrations. The adsorbed HA can be released from silica using neutral and basic aqueous solutions. HA ranging in size from ∼9 kDa to MDa polymers has been purified by this method from human serum and conditioned medium of cultured cells.

Hyaluronic Acid: A Valid Therapeutic Option for Early Management of Genitourinary Syndrome of Menopause in Cancer Survivors?

Genitourinary syndrome of menopause (GSM) is a chronic condition affecting a large number of women, with a major impact on their urogenital health and sexual function. It occurs at midlife because estrogen levels decline with menopause enhancing aging-related changes of the functional anatomy of the urogenital system. Unfortunately, GSM may occur early in the lifespan of women or be exacerbated following anticancer treatments, such as chemotherapy, ionizing radiation, or surgical removal of reproductive organs. Symptoms of GSM are often under-reported by women, under-estimated and under-diagnosed by health care providers (HCPs), and subsequently under-treated, despite their profound negative impact on the quality of life. The mainstay of vaginal treatments is local estrogen therapy (LET) ensuring an effective management of moderate to severe symptomatic GSM. However, LET is generally contraindicated in women with a history of hormone receptor positive cancer, due to the fear of increased recurrence or possible interference with endocrine adjuvant therapies. Among non-hormonal treatments, hyaluronic acid-based moisturizers have shown promising clinical results both in healthy women and in cancer patients or survivors. Its strong water-binding properties provide lubricating and moisturizing effects, which contribute to maintaining a proper level of hydration and viscoelasticity in several body parts, including the urinary tract and genital tissues. Hyaluronic acid-based moisturizers are effective, safe, and well tolerated; therefore, they may represent a valid option for the early management of GSM-associated symptoms in every woman with a history of cancer who is unable or unwilling to undergo hormone-based therapies. Hence, the aim of this review was to provide an overview of GSM etiology and treatment in women with natural or iatrogenic menopause, with a focus on the use of hyaluronic acid as a prophylactic treatment in the context of an integrated management protocol for cancer patients.

Musculoskeletal tissues-on-a-chip: role of natural polymers in reproducing tissue-specific microenvironments

Over the past years, 3D in vitro models have been widely employed in the regenerative medicine field. Among them, organ-on-a-chip technology has the potential to elucidate cellular mechanism exploiting multichannel microfluidic devices to establish 3D co-culture systems that offer control over the cellular, physico-chemical and biochemical microenvironments. To deliver the most relevant cues to cells, it is of paramount importance to select the most appropriate matrix for mimicking the extracellular matrix of the native tissue. Natural polymers-based hydrogels are the elected candidates for reproducing tissue-specific microenvironments in musculoskeletal tissue-on-a-chip models owning to their interesting and peculiar physico-chemical, mechanical and biological properties. Despite these advantages, there is still a gap between the biomaterials complexity in conventional tissue engineering and the application of these biomaterials in 3D in vitro microfluidic models. In this review, the aim is to suggest the adoption of more suitable biomaterials, alternative crosslinking strategies and tissue engineered-inspired approaches in organ-on-a-chip to better mimic the complexity of physiological musculoskeletal tissues. Accordingly, after giving an overview of the musculoskeletal tissue compositions, the properties of the main natural polymers employed in microfluidic systems are investigated, together with the main musculoskeletal tissues-on-a-chip devices.

Development, characterization and in vivo evaluation of the ointment containing hyaluronic acid for potential wound healing applications

Wound healing is a complex biological process. In this context, hyaluronic acid (HA) plays an important role in all phases of wound healing, from inflammation to the remodelling process. Nevertheless, its presence in adults decreases by 50% compared to newborns, which drastically reduces tissue regeneration. In this sense, this work presented a new method of extracting HA from chicken combs, as well as the development and in vivo evaluation of an ointment composed of vaseline, lanolin and HA 1% (w/w) for wound healing. The rheological analysis showed that the ointment containing HA has a viscoelastic behaviour. The in vivo test showed on the 7^th day that the group treated with the ointment containing HA had a wound area of 0.07 cm² against 0.09 cm² of the ointment without HA (vaseline, and lanolin). On the other hand, the groups treated with the HA ointment had a higher mean percentage of collagen and better healing on the 14^th day. The results of this paper indicate that the new method used to obtain HA is feasible, low-cost, and easy to obtain. Furthermore, the HA containing ointment improved wound healing. Therefore, the obtained ointment has great potential for use as an effective biomaterial in wound healing.

New Hyaluronic Acid from Plant Origin to Improve Joint Protection—An In Vitro Study

Background: In recent decades, hyaluronic acid (HA) has attracted great attention as a new treatment option for osteoarthritis. Classical therapies are not able to stop the cartilage degeneration process nor do they favor tissue repair. Nowadays, it is accepted that high molecular weight HA can reduce inflammation by promoting tissue regeneration; therefore, the aim of this study was to verify the efficacy of a new high molecular weight HA of plant origin (called GreenIuronic®) in maintaining joint homeostasis and preventing the harmful processes of osteoarthritis. Methods: The bioavailability of GreenIuronic® was investigated in a 3D intestinal barrier model that mimics human oral intake while excluding damage to the intestinal barrier. Furthermore, the chemical significance and biological properties of GreenIuronic® were investigated in conditions that simulate osteoarthritis. Results: Our data demonstrated that GreenIuronic® crosses the intestinal barrier without side effects as it has a chemical–biological profile, which could be responsible for many specific chondrocyte functions. Furthermore, in the osteoarthritis model, GreenIuronic® can modulate the molecular mechanism responsible for preventing and restoring the degradation of cartilage. Conclusion: According to our results, this new form of HA appears to be well absorbed and distributed to chondrocytes, preserving their biological activities. Therefore, the oral administration of GreenIuronic® in humans can be considered a valid strategy to obtain beneficial therapeutic effects during osteoarthritis.

Microorganism-derived biological macromolecules for tissue engineering

According to literature, certain microorganism productions mediate biological effects. However, their beneficial characteristics remain unclear. Nowadays, scientists concentrate on obtaining natural materials from live creatures as new sources to produce innovative smart biomaterials for increasing tissue reconstruction in tissue engineering and regenerative medicine. The present review aims to introduce microorganism-derived biological macromolecules, such as pullulan, alginate, dextran, curdlan, and hyaluronic acid, and their available sources for tissue engineering. Growing evidence indicates that these materials can be used as biological material in scaffolds to enhance regeneration in damaged tissues and contribute to cosmetic and dermatological applications. These natural-based materials are attractive in pharmaceutical, regenerative medicine, and biomedical applications. This study provides a detailed overview of natural-based biomaterials, their chemical and physical properties, and new directions for future research and therapeutic applications.

Comprehensive review on biotechnological production of hyaluronic acid: status, innovation, market and applications

The growing, existing demand for low-cost and high-quality hyaluronic acid (HA) needs an outlook of different possible production strategies from renewable resources with the reduced possibility of cross-infections. Recently, the possibility of producing HA from harmless microorganisms appeared, which offers the opportunity to make HA more economical, without raw material limitations, and environmentally friendly. HA production is mainly reported with Lancefield Streptococci A and C, particularly from S. equi and S. zooepidemicus. Various modes of fermentation such as batch, repeated batch, fed-batch, and continuous culture have been investigated to optimize HA production, particularly from S. zooepidemicus, obtaining a HA yield of 2.5 g L⁻¹ – 7.0 g L⁻¹. Among the different utilized DSP approaches of HA production, recovery with cold ethanol (4°C) and cetylpyridinium chloride is the ideal strategy for lab-scale HA production. On the industrial scale, besides using isopropanol, filtration (0.22 um), ultrafiltration (100 kDa), and activated carbon absorption are employed to obtain HA of low molecular weight and additional ultrafiltration to purify HA of higher MW. Even though mature technologies have already been developed for the industrial production of HA, the projections of increased sales volume and the expansion of application possibilities require new processes to obtain HA with higher productivity, purity, and specific molecular weights. In this review, we have put forth the progress of HA technological research by discussing the microbial biosynthetic aspects, fermentation and downstream strategies, industrial-scale scenarios of HA, and the prospects of HA production to meet the current and ongoing market demands.

Hyaluronic Acid: Known for Almost a Century, but Still in Vogue

Hyaluronic acid (HA) has a special position among glycosaminoglycans. As a major component of the extracellular matrix (ECM). This simple, unbranched polysaccharide is involved in the regulation of various biological cell processes, whether under physiological conditions or in cases of cell damage. This review summarizes the history of this molecule’s study, its distinctive metabolic pathway in the body, its unique properties, and current information regarding its interaction partners. Our main goal, however, is to intensively investigate whether this relatively simple polymer may find applications in protecting against ionizing radiation (IR) or for therapy in cases of radiation-induced damage. After exposure to IR, acute and belated damage develops in each tissue depending upon the dose received and the cellular composition of a given organ. A common feature of all organ damage is a distinct change in composition and structure of the ECM. In particular, the important role of HA was shown in lung tissue and the variability of this flexible molecule in the complex mechanism of radiation-induced lung injuries. Moreover, HA is also involved in intermediating cell behavior during morphogenesis and in tissue repair during inflammation, injury, and would healing. The possibility of using the HA polymer to affect or treat radiation tissue damage may point to the missing gaps in the responsible mechanisms in the onset of this disease. Therefore, in this article, we will also focus on obtaining answers from current knowledge and the results of studies as to whether hyaluronic acid can also find application in radiation science.

Mesenchymal stem cell-encapsulated cellulose nanofiber microbeads and enhanced biological activities by hyaluronic acid incorporation

Cell microencapsulation is a process to entrap viable and functional cells within a biocompatible and semi-permeable matrix to provide a favorable microenvironment to the cells. Cellulose nanofiber (CNF), a low-cost and sustainable cellulose-derived natural polymer, has been studied as a matrix for 3D stem cell culture in the form of a bulk hydrogel. Here, the preparation of CNF microbeads for the long-term 3D culture of human adipose-derived stem cells (hADSCs) was demonstrated. Furthermore, hyaluronic acid (HA) was physically incorporated into the stem cell encapsulated CNF microbeads with various molecular weights and concentrations to investigate its potential in enhancing the cellular bioactivities. The beneficial effects of HA incorporation on encapsulated cells were significant compared to CNF microbeads, especially with 700 kDa molecular weight and 0.2% in concentration in terms of cell proliferation (~2 times) and VEGF secretion (~2 times) while maintaining their stemness. All the results demonstrated that the HA-incorporated CNF microbeads could serve as a promising microencapsulation matrix for hADSCs.

A Novel Device for the Quantification of Synovial Fluid Viscosity via Magnetic Deflection

Changes in synovial fluid viscosity may be used to detect joint disease; however, methods to evaluate these changes at the point of care are rudimentary. Previously, we demonstrated magnetic particle translation through synovial fluid could serve as a surrogate marker of synovial fluid mechanics. In this work, the relationship of magnetic deflection of a stream of particles is examined in relation to synovial fluid mechanics. A flow device was designed to assess the deflection of a magnetic particle stream as it flows past a fixed permanent magnet. Deflection is recorded via a camera, measuring the deflection distance of the particle stream at a given distance. Theoretically, as fluid viscosity decreases, the deflection of the particle stream should increase. To validate this approach, particle deflection was first measured in Newtonian glycerol solutions of varying viscosity under different flow conditions. Next, the device was used to test synovial fluid viscosity in bovine synovial fluid that was progressively degraded using ultrasonication. A strong correlation was observed between the deflection of the magnetic particles and the viscosity of the glycerol solutions (R2=0.987) and the degradation of synovial fluid (R2=0.7045). Moreover, this approach does not require particles to be separated from the fluid for quantification and serves as a proof-of-principle for future lab-on-a-chip assessments of synovial fluid biomechanics.

An Overview of Soft Tissue Fillers for Cosmetic Dermatology: From Filling to Regenerative Medicine

Hyaluronic acid (HA)-based injectable filling agents are at the forefront of the current demand for noninvasive dermatological procedures for the correction of age-related soft tissue defects. The present review aims to summarize currently available HA-based products and critically appraise their differences in rheological nature and clinical application. Linear HA (LHA) gels may be supplemented with amino acids, lipoic acid, vitamins, nucleosides, or minerals for synergistic antiaging and antioxidant benefits (polycomponent LHA). HA hydrogels can be generated via chemical or physical crosslinking, which increases their elasticity and decreases viscosity. The performance of crosslinked fillers depends on HA concentration, degree of crosslinking, elastic modulus, cohesivity, and type of crosslinking agent employed. PEG-crosslinked LHA displays improved elasticity and resistance to degradation, and lower swelling rates as compared to BDDE-crosslinked LHA. Physical crosslinking stabilizes HA hydrogels without employing exogenous chemical compounds or altering hyaluronans’ natural molecular structure. Thermally stabilized hybrid cooperative HA complexes (HCC) are a formulation of high- and low-molecular-weight (H-HA and L-HA) hyaluronans, achieving high HA concentration, low viscosity with optimal tissue diffusion, and a duration comparable to weakly cross-linked gel. Our critical analysis evidences the importance of understanding different fillers’ properties to assist physicians in selecting the most appropriate filler for specific uses and for predictable and sustainable results.

Hyaluronic acid-based nanoplatforms for Doxorubicin: A review of stimuli-responsive carriers, co-delivery and resistance suppression

An important motivation for the use of nanomaterials and nanoarchitectures in cancer therapy emanates from the widespread emergence of drug resistance. Although doxorubicin (DOX) induces cell cycle arrest and DNA damage by suppressing topoisomerase activity, resistance to DOX has severely restricted its anti-cancer potential. Hyaluronic acid (HA) has been extensively utilized for synthesizing nanoparticles as it interacts with CD44 expressed on the surface of cancer cells. Cancer cells can take up HA-modified nanoparticles through receptor-mediated endocytosis. Various types of nanostructures such as carbon nanomaterials, lipid nanoparticles and polymeric nanocarriers have been modified with HA to enhance the delivery of DOX to cancer cells. Hyaluronic acid-based advanced materials provide a platform for the co-delivery of genes and drugs along with DOX to enhance the efficacy of anti-cancer therapy and overcome chemoresistance. In the present review, the potential methods and application of HA-modified nanostructures for DOX delivery in anti-cancer therapy are discussed.

Validation of an Analytical Method for the Simultaneous Determination of Hyaluronic Acid Concentration and Molecular Weight by Size-Exclusion Chromatography

The hyaluronic acid (HA) global market growth can be attributed to its use in medical, cosmetic, and pharmaceutical applications; thus, it is important to have validated, analytical methods to ensure confidence and security of its use (and to save time and resources). In this work, a size-exclusion chromatography method (HPLC-SEC) was validated to determine the concentration and molecular distribution of HA simultaneously. Analytical curves were developed for concentration and molecular weight in the ranges of 100-1000 mg/L and 0.011-2.200 MDa, respectively. The HPLC-SEC method showed repeatability and reproducibility greater than 98% and limits of detection and quantification of 12 and 42 mg/L, respectively, and was successfully applied to the analysis of HA from a bacterial culture, as well as cosmetic, and pharmaceutical products.

Primary recovery of hyaluronic acid produced in Streptococcus equi subsp. zooepidemicus using PEG-citrate aqueous two-phase systems

Given its biocompatibility, rheological, and physiological properties, hyaluronic acid (HA) has become a biomaterial of increasing interest with multiple applications in medicine and cosmetics. In recent decades, microbial fermentations have become an important source for the industrial production of HA. However, due to its final applications, microbial HA must undergo critical and long purification processes to ensure clinical and cosmetic grade purity. Aqueous two-phase systems (ATPS) have proven to be an efficient technique for the primary recovery of high-value biomolecules. Nevertheless, their implementation in HA downstream processing has been practically unexplored. In this work, polyethylene glycol (PEG)–citrate ATPS were used for the first time for the primary recovery of HA produced with an engineered strain of Streptococcus equi subsp. zooepidemicus. The effects of PEG molecular weight (MW), tie-line length (TLL), volume ratio (V_R), and sample load on HA recovery and purity were studied with a clarified fermentation broth as feed material. HA was recovered in the salt-rich bottom phase, and its recovery increased when a PEG MW of 8000 g mol⁻¹ was used. Lower V_R values (0.38) favoured HA recovery, whereas purity was enhanced by a high V_R (3.50). Meanwhile, sample load had a negative impact on both recovery and purity. The ATPS with the best performance was PEG 8000 g mol⁻¹, TLL 43% (w/w), and V_R 3.50, showing 79.4% HA recovery and 74.5% purity. This study demonstrated for the first time the potential of PEG–citrate ATPS as an effective primary recovery strategy for the downstream process of microbial HA.

3D stem cell-laden artificial endometrium: successful endometrial regeneration and pregnancy

Thin endometrium lining or severe endometrial injury which may occur during artificial abortion can cause defective endometrial receptivity and subsequent infertility. Therefore, much effort has been devoted toward regenerating thin or damaged endometrial lining by applying multiple types of stem cells. Even though there are some positive preliminary outcomes, repairing the injured endometrium with stem cells is considerably challenging, due to the lack of an adequate microenvironment for the administrated stem cells within the tissues and subsequent poor therapeutic efficiency. In this context, as an alternative, we fabricated a 3D stem cell-laden artificial endometrium by incorporating several biodegradable biomaterials (collagen and hyaluronic acid) and multiple cellular components of endometrium (endometrial stem cells, stromal cells, and vessel cells) to properly recapitulate the multicellular microenvironment and multilayered structure. Agarose was used as an inert filler substrate to enhance the mechanical integrity of the three-layered artificial endometrium. Various mechanical characteristics, such as morphology, compression properties, swelling, and viscosity, have been evaluated. Various biological features, such as steroid hormone responsiveness, specific endometrial cell-surface marker expressions, and the secretion of multiple growth factors and steroid hormones, as well as the viability of encapsulated endometrial cells are relatively well maintained within the artificial endometrium. More importantly, severe tissue injuries were significantly relieved by transplanting our 3D artificial endometrium into endometrial ablation mice. Remarkably, artificial endometrium transplantation resulted in a successful pregnancy with subsequent live birth without any morphological or chromosomal abnormalities.

Recent advances and prospects of hyaluronan as a multifunctional therapeutic system

Hyaluronan (HA) is a naturally occurring non-sulfated glycosaminoglycan (GAG), cell-surface-associated biopolymer and is the key component of tissue extracellular matrix (ECM). Along with remarkable physicochemical properties, HA also has multifaceted biological effects that include but not limited to ECM organization, immunomodulation, and various cellular processes. Environmental cues such as tissue injury, infection or cancer change downstream signaling functionalities of HA. Unlike native HA, the fragments of HA have diversified effects on inflammation, cancer, fibrosis, angiogenesis and autoimmune response. In this review, we aim to discuss HA as a therapeutic delivery system development process, source, biophysical-chemical properties, and associated biological pathways (especially via cell surface receptors) of native and fragmented HA. We also tried to address an overview of the potential role of HA (native HA vs fragments) in the modulation of inflammation, immune response and various cancer targeting delivery applications. This review will also highlight the HA based therapeutic systems, medical devices and future perspectives of various biomedical applications were discussed in detail.

Abundance and size of hyaluronan in naked mole-rat tissues and plasma

Large amounts of ultra-high molecular weight hyaluronan (HA) have been described as the main cause of cancer resistance in naked mole-rats (Heterocephalus glaber, NMR). Our work examined HA metabolism in these rodents more closely. HA was localized and quantified using HA binding proteins. Its molecular weight was determined using size exclusion chromatography and gel electrophoresis, HA family gene expression using RNAseq analysis, and hyaluronidase activity using zymography. Guinea pigs (Cavia porcellus) and mice (Mus musculus) were used as controls for some experiments. We found that HA localization was similar in NMR, guinea pig, and mouse tissues but NMR had larger amounts and higher molecular weight (maximum, around 2.5 MDa) of HA in serum and almost all tissues tested. We could not find ultra-high molecular weight HA (≥ 4 MDa) in NMR samples, in contrast to previous descriptions. Hyaluronidase-1 had lower expression and activity in NMR than mouse lymph nodes. RNAseq results showed that, among HA family genes, Tnfaip6 and hyaluronidase-3 (Hyal3) were systematically overexpressed in NMR tissues. In conclusion, NMR samples, contrary to expectations, do not harbor ultra-high molecular weight HA, although its amount and average molecular weight are higher in NMR than in guinea pig tissues and serum. Although hyaluronidase expression and activity are lower in NMR than mouse lymph nodes, this not sufficient to explain the presence of high molecular weight HA. A different activity of the NMR HA synthases remains possible. These characteristics, together with extremely high Hyal3 and Tnfaip6 expression, may provide the NMR with a bespoke, and perhaps protective, HA metabolism.

Regulation of the expression of proinflammatory cytokines induced by SARS-CoV-2

An outbreak of a novel coronavirus was reported in Wuhan, China, in late 2019. It has spread rapidly through China and many other countries, causing a global pandemic. Since February 2020, over 28 countries/regions have reported confirmed cases. Individuals with the infection known as coronavirus disease-19 (COVID-19) have similar clinical features as severe acute respiratory syndrome first encountered 17 years ago, with fever, cough, and upper airway congestion, along with high production of proinflammatory cytokines (PICs), which form a cytokine storm. PICs induced by COVID-19 include interleukin (IL)-6, IL-17, and monocyte chemoattractant protein-1. The production of cytokines is regulated by activated nuclear factor-kB and involves downstream pathways such as Janus kinase/signal transducers and activators transcription. Protein expression is also regulated by post-translational modification of chromosomal markers. Lysine residues in the peptide tails stretching out from the core of histones bind the sequence upstream of the coding portion of genomic DNA. Covalent modification, particularly methylation, activates or represses gene transcription. PICs have been reported to be induced by histone modification and stimulate exudation of hyaluronic acid, which is implicated in the occurrence of COVID-19. These findings indicate the impact of the expression of PICs on the pathogenesis and therapeutic targeting of COVID-19.

Effect of Hofmeister Ions on Transport Properties of Aqueous Solutions of Sodium Hyaluronate

Tracer diffusion coefficients obtained from the Taylor dispersion technique at 25.0 °C were measured to study the influence of sodium, ammonium and magnesium salts at 0.01 and 0.1 mol dm⁻³ on the transport behavior of sodium hyaluronate (NaHy, 0.1%). The selection of these salts was based on their position in Hofmeister series, which describe the specific influence of different ions (cations and anions) on some physicochemical properties of a system that can be interpreted as a salting-in or salting-out effect. In our case, in general, an increase in the ionic strength (i.e., concentrations at 0.01 mol dm⁻³) led to a significant decrease in the limiting diffusion coefficient of the NaHy 0.1%, indicating, in those circumstances, the presence of salting-in effects. However, the opposite effect (salting-out) was verified with the increase in concentration of some salts, mainly for NH₄SCN at 0.1 mol dm⁻³. In this particular salt, the cation is weakly hydrated and, consequently, its presence does not favor interactions between NaHy and water molecules, promoting, in those circumstances, less resistance to the movement of NaHy and thus to the increase of its diffusion (19%). These data, complemented by viscosity measurements, permit us to have a better understanding about the effect of these salts on the transport behaviour of NaHy.

Different Effects of Albumin and Hydroxyethyl Starch on Low Molecular-Weight Solute Permeation through Sodium Hyaluronic Acid Solution

Hyaluronic acid (HA), a high-molecular-weight linear polysaccharide, restricts solute transport through the interstitial space. Albumin and hydroxyethyl starch (HES) solutions are used to correct the decrease of blood volume during surgery, but may leak into the interstitial space under inflammation conditions. Given the possibility that the structure of HA may be affected by adjacent macromolecules, this study tested whether albumin and HES (M_w 130,000) exert different effects on solute permeation through sodium hyaluronic acid (NaHA: M_w 1.3 × 10⁶) solution. To this end, permeation of Orange G, a synthetic azo dye (M_w 452), into NaHA solutions containing albumin or HES over time was assessed. The amount of time it took for the relative absorbance of Orange G to reach 0.3 (T_0.3) was determined in each NaHA solution relative to the reference solution (i.e., colloid solution without NaHA). Relative T_0.3 values of albumin were larger than those of HES for 0.1% NaHA solution (3.33 ± 0.69 vs. 1.16 ± 0.08, p = 0.006, n = 3) and 0.2% NaHA solution (1.95 ± 0.32 vs. 0.92 ± 0.27, p = 0.013, n = 3). This finding may help in the selection of an appropriate colloid solution to control drug delivery into the interstitial space of cancer tissue under inflammation conditions.

Semiflexible polymer scaffolds: an overview of conjugation strategies

Semiflexible polymers are excellent scaffolds for the presentation of a wide variety of (bio)molecules. This manuscript reviews advantages and challenges of the most common conjugation strategies for the major classes of semiflexible polymers.

Quantitative analysis of gliding between subcutaneous tissue and the vastus lateralis - Influence of the dense connective tissue of the myofascia

INTRODUCTION

The thickness of connective tissue has been shown to be associated with pain (Stecco et al., 2014). However, the relationship between fascial thickness and gliding remains unclear. In addition, the influence between gliding and the motion rhythm and limb position isn't clear.

METHOD

A therapist moved patient's lower leg at one of two constant rhythms (40 or 60bpm). Gliding of both the vastus lateralis (VL) muscle and subcutaneous (SC) tissue were recorded during knee motion using ultrasonography. Particle image velocimetry analysis software was adapted to create the flow velocity from echo imaging. Gliding was calculated using a coefficient of correlation from each flow velocity. Myofascial thickness and SC were measured using Image-J. The ratios of the loose connective tissue (LCT) and dense connective tissue (DCT) thickness to the total myofascial thickness were calculated. Repeated-measures two-way ANOVA was used to compare the two motion rhythms and three positions, with stepwise multiple regression analysis to analyze the predictors that influenced the gliding coefficient at each rhythm.

RESULTS

Repeated-measures two-way ANOVA showed that the effect of rhythm was statistically significant, but the effect of position was not. At a 40 bpm rhythm, stepwise multiple regression analysis selected SC thickness and DCT thickness as significant factors, while at a 60 bpm rhythm, SC thickness and DCT ratio were selected.

CONCLUSION

This study revealed that increased thickness of DCT of the myofascia and SC resulted in decreased gliding between the VL and SC, demonstrating that gliding is related to fascial thickness. Motion rhythm influences gliding between tissues.

A hyaluronic acid-based filler reduces lipolysis in human mature adipocytes and maintains adherence and lipid accumulation of long-term differentiated human preadipocytes

The beneficial role of subcutaneous adipose tissue in skin rejuvenation derived from its capacity to fill the under‐layer volumes but also from its ability to regulate the extracellular matrix production by dermis fibroblasts. Hyaluronic acid (HA), a major component of the extracellular matrix, is a commonly used injectable dermal filler showing excellent efficiencies to maintain tissue augmentation even after its biodegradation. To improve their stability, the HA molecules can also be “cross‐linked” to each other. The effects of cross‐linked HA‐based fillers on the dermal structure are well known. For safety reasons, most of the physicians prefer to use the blunt cannula for injections. However, evidences showed that the cannula could not be located in the dermis, but it passes through immediate hypodermis and the long‐lasting effect of cross‐linked HA‐based fillers may be related to its effects on adipose tissue. To test whether cross‐linked HA has a direct effect on human adipocytes, we treated isolated adipocytes and precursors cells from human skin donors with cross‐linked HA. Biochemical and cellular analysis demonstrated that treatment by cross‐linked HA showed beneficial effects on differentiated cell adherence and survival as well as reduced basal and induced lipolysis in fully mature adipocytes. Taken together, these data showed that cross‐linked HA promoted cell adherence and preserved the adipogenic capacity of preadipocytes during prolonged cell culture, bringing additional evidences of the beneficial role of cross‐linked HA‐based fillers in maintenance of the subcutaneous fat mass. This first study could defend a preventive approach to facial volume loss during natural aging.

Hyaluronic Acid Nanoparticles as Nanomedicine for Treatment of Inflammatory Diseases

Owing to their unique biological functions, hyaluronic acid (HA) and its derivatives have been explored extensively for biomedical applications such as tissue engineering, drug delivery, and molecular imaging. In particular, self-assembled HA nanoparticles (HA-NPs) have been used widely as target-specific and long-acting nanocarriers for the delivery of a wide range of therapeutic or diagnostic agents. Recently, it has been demonstrated that empty HA-NPs without bearing any therapeutic agent can be used therapeutically for the treatment of inflammatory diseases via modulating inflammatory responses. In this review, we aim to provide an overview of the significant achievements in this field and highlight the potential of HA-NPs for the treatment of inflammatory diseases.

Influence of the Molecular Weight and the Presence of Calcium Ions on the Molecular Interaction of Hyaluronan and DPPC

Hyaluronan is an essential physiological bio macromolecule with different functions. One prominent area is the synovial fluid which exhibits remarkable lubrication properties. However, the synovial fluid is a multi-component system where different macromolecules interact in a synergetic fashion. Within this study we focus on the interaction of hyaluronan and phospholipids, which are thought to play a key role for lubrication. We investigate how the interactions and the association structures formed by hyaluronan (HA) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) are influenced by the molecular weight of the bio polymer and the ionic composition of the solution. We combine techniques allowing us to investigate the phase behavior of lipids (differential scanning calorimetry, zeta potential and electrophoretic mobility) with structural investigation (dynamic light scattering, small angle scattering) and theoretical simulations (molecular dynamics). The interaction of hyaluronan and phospholipids depends on the molecular weight, where hyaluronan with lower molecular weight has the strongest interaction. Furthermore, the interaction is increased by the presence of calcium ions. Our simulations show that calcium ions are located close to the carboxylate groups of HA and, by this, reduce the number of formed hydrogen bonds between HA and DPPC. The observed change in the DPPC phase behavior can be attributed to a local charge inversion by calcium ions binding to the carboxylate groups as the binding distribution of hyaluronan and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine is not changed.

Effect of Hyaluronic Acid Filler Injection on the Interdental Papilla in a Mouse Model of Open Gingival Embrasure

The black triangle resulting from interdental papilla (IDP) loss is associated with poor aesthetics and difficulty in pronunciation and food impaction. There is limited knowledge of gingival tissue inflammatory response to hyaluronic acid (HA) filler injection, a minimally invasive IDP reconstruction method. This study aimed to examine the morphological and histological changes in IDP and the inflammatory cytokine localization to the IDP post-HA filler injection using an open gingival embrasure (OGE) mouse model. Mice from the control, sham, and OGE groups were attached with reference, inactive, and activated wires for 5 days, respectively. The degree of IDP loss was determined based on the spring-papilla distance (SPD). Morphological and histological changes in the OGE group injected with phosphate-buffered saline (PBS) or HA fillers were examined on days 2 and 7 post-injection. Immunohistochemical analysis was performed to determine the localization patterns of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, myeloperoxidase (MPO), and Ki67. Five days post-wire attachment, the control and OGE groups exhibited a significantly higher SPD than the sham group (p < 0.0167). The SPD of the HA filler injection group was significantly lower than that of the PBS injection group on days 2, 4, and 7 post-injection (p < 0.05). The IDP of the OGE group was wide and flat. HA filler was stable in the connective tissue underlying the epithelial tissue even on day 7 post-injection. TNF-α, IL-1β, IL-6, MPO, and Ki67 were highly localized to the connective tissue surrounding the filler on day 2, which decreased on day 7 post-injection. Thus, HA filler can safely and successfully reconstruct the IDP in cases of OGE.