Enzymatically stable unsaturated hyaluronan-derived oligosaccharides with selective cytostatic properties

Hyaluronan, a linear glycosaminoglycan comprising D-N-acetylglucosamine and D-glucuronic acid, is the main component of the extracellular matrix. Its influence on cell proliferation, migration, inflammation, signalling, and other functions, depends heavily on its molecular weight and chemical modification. Unsaturated HA oligosaccharides are available in defined length and purity. Their potential therapeutic utility can be further improved by chemical modification, e. g., reduction. No synthesis of such modified oligosaccharides, either stepwise or by hyaluronan cleavage, has been reported yet. Here we show a three-step synthesis (esterification, depolymerization and reduction) of unsaturated even numbered hyaluronan oligosaccharides with carboxylates and the reducing terminus reduced to an alcohol. Particular oligosaccharides were synthesised. The modified oligosaccharides are not cleaved by mammalian or bacterial hyaluronidase and do not affect the growth of mouse and human fibroblasts. Further, MTT and NRU viability tests showed that they inhibit the growth of human colon carcinoma cells HT-29 by 20-50 % in concentrations 500-1000 μg/mL. Interestingly, this effect takes place regardless of CD44 receptor expression and was not observed with unmodified HA oligosaccharides. These compounds could serve as enzymatically stable building blocks for biologically active substances.

Low, medium, and high molecular weight hyaluronic acid effects on human dental pulp stem cells in vitro

Hyaluronic acid (HA), an extracellular biopolymer found throughout the human body, holds promise as a biocompatible and biodegradable scaffold material. High molecular weight (HMW) HA degrades, generating low molecular weight (LMW) fragments with distinct properties. These fragments can influence the behaviour of cells, including human dental pulp stem cells (hDPSCs) incorporated into HA-containing hydrogels or scaffolds. Therefore, a comprehensive examination of the impact of a range of HA molecular weights on hDPSCs is essential before designing HA-based scaffolds for these cells. hDPSC lines were cultured with LMW HA (800 Da, 1600 Da, 15 kDa), medium molecular weight HA (237 kDa), or HMW HA (1500 kDa) over six passages. The various molecular weights had negligible effects on hDPSCs viability, morphology, adhesion, or relative telomere length. Furthermore, the expression of key surface stemness markers (CD29, CD44, CD73, CD90) remained unaltered. HA did not induce osteogenic, chondrogenic, or adipogenic differentiation. Moreover, the potential for chondrogenic and osteogenic differentiation was not adversely affected by LMW or HMW HA. Various molecular weights of HA seem safe, biocompatible and therefore suitable components for hDPSCs-containing scaffolds. These findings affirm that the hDPCSs will not be negatively affected by HA fragments resulting from scaffold degradation.

Injecting hyaluronan in the thoracolumbar fascia: A model study

Hyaluronan (HA) has been recently identified as a key component of the densification of thoracolumbar fascia (TLF), a potential contributor to non-specific lower back pain (LBP) currently treated with manual therapy and systemic or local delivery of anti-inflammatory drugs. The aim of this study was to establish a novel animal model suitable for studying ultrasound-guided intrafascial injection prepared from HA with low and high Mw. Effects of these preparations on the profibrotic switch and mechanical properties of TLF were measured by qPCR and rheology, respectively, while their lubricating properties were evaluated by tribology. Rabbit proved to be a suitable model of TLF physiology due to its manageable size enabling both TLF extraction and in situ intrafascial injection. Surprisingly, the tribology showed that low Mw HA was a better lubricant than the high Mw HA. It was also better suited for intrafascial injection due to its lower injection force and ability to freely spread between TLF layers. No profibrotic effects of either HA preparation in the TLF were observed. The intrafascial application of HA with lower MW into the TLF appears to be a promising way how to increase the gliding of the fascial layers and target the myofascial LBP.

Synthesis and self-assembling of hyaluronan grafted with ceramide NP for topical drug delivery

In this work, amphiphilic hyaluronan was synthesized by grafting succinylated N-oleoyl-phytosphingosine via esters bonds. Succinylated N-oleoyl-phytosphingosine (sCER) was first prepared by esterification of hydroxyl moieties of the ceramide with succinic anhydride. The esterification of hyaluronan was governed by crowding effect. The oligomeric HA-sCER derivatives exhibited a strong self-aggregation as evidenced by a very low critical aggregation concentration (1.9 μg mL-1), higher pyrene binding constant (KB), and the smallest particle size (30 nm) in solution. The self-aggregation properties demonstrated to be a function of the substitution degree and molecular weight of HA. The prepared derivatives were non-cytotoxic towards cell lines NIH-3T3. Nanoparticles prepared using oligomeric HA-sCER derivatives improved the penetration of Nile red dye through the stratum corneum due to their smaller size (≤50 nm). The fluorescence intensity localized at the stratum corneum was higher for oligomeric HA-sCER. A significant inhibition of the pro-inflammatory cytokine interleukin-6 production was observed in vitro in macrophages differentiated from THP-1 cells. These findings showed that HA-sCER constituted a promising active ingredient for cosmetics use.

Modified hyaluronic acid with enhanced resistance to degradation

A mild and efficient reduction of negatively charged glucuronate units of hyaluronic acid (HA) into less polar glucose units has not been reported yet. However, this modification could significantly affect physical and chemical properties. Here we show a one-pot procedure where HA is converted into its derivate with carboxyl groups reduced to primary alcohols (HA-Red) without severe polymer degradation. Optimized synthesis aimed at aqueous solutions allowed the preparation of polysaccharides with molecular weights up to 1000 kDa. The chemical structure of HA-Red was proved by 2-dimensional NMR methodologies, FT-IR, LC-MS and SECMALLS. The final materials were exposed to a higher temperature or digested with bovine testicular hyaluronidase (BTH). Obtained data proved higher stability of HA-Red compared to HA, and significant dependence of stability on the degree of modification was observed in most cases. Preliminary in vitro studies showed no negative effects of HA-Red on the growth of 3T3 fibroblasts, which may be promising for applications requiring biodegradable and biocompatible HA derivatives with increased resistance to degradation.

The hyaluronan metabolism in the UV-irradiated human epidermis and the relevance of in vitro epidermal models

Exposure to the sun affects the skin and may eventually result in UV-induced skin damage. It is generally known that hyaluronan (HA) is one of the main structural and functional components of the skin. However, UV-related changes in the HA metabolism in the skin have not yet been elucidated. Using qRT-PCR, confocal microscopy and LC-MS/MS we compared the naturally sun-exposed (SE), sun-protected, experimentally repeatedly UVA + UVB-exposed and acutely (once) UVA + UVB irradiated skin of Caucasian women. The epidermis was harvested by means of suction blistering 24 h after the acute irradiation. In addition, the epidermis was compared with a UV-irradiated in vitro reconstituted 3D epidermis (EpiDerm) and an in vitro 2D culture of normal human keratinocytes (NHEK). The amount of HA was found to be statistically significantly enhanced in the acutely irradiated epidermis. The acute UV evinced the upregulation of HA synthases (HAS2 and HAS3), hyaluronidases (HYAL2 and HYAL3), Cluster of differentiation 44 (CD44), and Cell Migration Inducing Proteins (CEMIP and CEMIP2), while only certain changes were recapitulated in the 3D epidermis. For the first time, we demonstrated the enhanced gene and protein expression of CEMIP and CEMIP2 following UV irradiation in the human epidermis. The data suggest that the HA metabolism is affected by UV in the irradiated epidermis and that the response can be modulated by the underlying dermis.

An in vitro model that mimics the foreign body response in the peritoneum: Study of the bioadhesive properties of HA-based materials

A cascade of reactions known as the foreign body response (FBR) follows the implantation of biomaterials leading to the formation of a fibrotic capsule around the implant and subsequent health complications. The severity of the FBR is driven mostly by the physicochemical characteristics of implanted material, the method and place of implantation, and the degree of immune system activation. Here we present an in vitro model for assessing new materials with respect to their potential to induce a FBR in the peritoneum. The model is based on evaluating protein sorption and cell adhesion on the implanted material. We tested our model on the free-standing films prepared from hyaluronan derivatives with different hydrophobicity, swelling ratio, and rate of solubilization. The proteomic analysis of films incubated in the mouse peritoneum showed that the presence of fibrinogen was driving the cell adhesion. Neither the film surface hydrophobicity/hydrophilicity nor the quantity of adsorbed proteins were decisive for the induction of the long-term cell adhesion leading to the FBR, while the dissolution rate of the material proved to be a crucial factor. Our model thus helps determine the probability of a FBR to materials implanted in the peritoneum while limiting the need for in vivo animal testing.

Molecular weight and gut microbiota determine the bioavailability of orally administered hyaluronic acid

The ability of hyaluronan as a dietary supplement to increase skin moisture and relieve knee pain has been demonstrated in several clinical studies. To understand the mechanism of action, determining hyaluronan's bioavailability and in vivo fate is crucial. Here, we used ¹³C-hyaluronan combined with LC-MS analysis to compare the absorption and metabolism of oral hyaluronan in germ-free and conventional wild-type mice. The presence of Bacteroides spp. in the gut was crucial for hyaluronan absorption. Specific microorganisms cleave hyaluronan into unsaturated oligosaccharides (<3 kDa) which are partially absorbed through the intestinal wall. The remaining hyaluronan fragments are metabolized into short-chain fatty acids, which are only metabolites available to the host. The poor bioavailability (~0.2 %) of oral hyaluronan indicates that the mechanism of action is the result of the systematic regulatory function of hyaluronan or its metabolites rather than the direct effects of hyaluronan at distal sites of action (skin, joints).

Intraperitoneally administered native and lauroyl-modified hyaluronan films: Pharmacokinetic and metabolism studies

Hyaluronan is being investigated extensively as a biocompatible and biodegradable material for use in biomedical applications. While the derivatization of hyaluronan broadens its potential therapeutic use, the pharmacokinetics and metabolization of the derivatives must be thoroughly investigated. The fate of intraperitoneally-applied native and lauroyl-modified hyaluronan films with varying degrees of substitution was investigated in-vivo employing an exclusive stable isotope-labelling approach and LC-MS analysis. The materials were gradually degraded in peritoneal fluid, lymphatically absorbed, preferentially metabolized in the liver and eliminated without any observable accumulation in the body. Hyaluronan acylation prolongs its presence in the peritoneal cavity depending on the degree of substitution. The safety of acylated hyaluronan derivatives was confirmed via a metabolic study that revealed its degradation into non-toxic metabolites, i.e. native hyaluronan and free fatty acid. Stable isotope-labelling with LC-MS tracking comprises a high-quality procedure for the investigation of the metabolism and biodegradability of hyaluronan-based medical products in-vivo.

Retinoic Acid Grafted to Hyaluronic Acid Activates Retinoid Gene Expression and Removes Cholesterol from Cellular Membranes

All-trans-retinoic acid (atRA) is a potent ligand that regulates gene expression and is used to treat several skin disorders. Hyaluronic acid (HA) was previously conjugated with atRA (HA-atRA) to obtain a novel amphiphilic compound. HA-atRA forms micelles that incorporate hydrophobic molecules and facilitate their transport through the skin. The aim of this study was to determine the influence of HA-atRA on gene expression in skin cells and to compare it with that of unbound atRA. Gene expression was investigated using microarrays and a luciferase system with a canonical atRA promoter. HA-atRA upregulated gene expression similarly to atRA. However, HA-atRA activated the expression of cholesterol metabolism genes, unlike atRA. Further investigation using HPLC and filipin III staining suggested that the treated cells induced cholesterol synthesis to replenish the cholesterol removed from the cells by HA-atRA. HA modified with oleate (HA-C18:1) removed cholesterol from the cells similarly to HA-atRA, suggesting that the cholesterol removal stemmed from the amphiphilic nature of the two derivatives. HA-atRA induces retinoid signaling. Thus, HA-atRA could be used to treat skin diseases, such as acne and psoriasis, where the combined action of atRA signaling and anti-inflammatory cholesterol removal may be potentially beneficial.

Insoluble hyaluronan films obtained by heterogeneous crosslinking with iron(III) as resorbable implants

We present water-insoluble hyaluronan films crosslinked by trivalent iron developed as potential resorbable implants. The films were crosslinked by sorption of ferric salt into solid HA films in water/2-propanol bath. These heterogeneously crosslinked films (het-FeHA) remained tough and dimensionally stable when rehydrated in saline. In contrast, films prepared by drying the well-known homogeneous ferric hyaluronate gels (hom-FeHA) softened upon rehydration and expanded rapidly. Differences between hom-FeHA and het-FeHA result from polymer network topology (dominant inter- or intra-molecular crosslink, respectively). Moreover, Mössbauer spectroscopy of het-FeHA revealed diiron complexes, while iron in the hom-FeHA was present exclusively as γ-FeOOH nanoparticles or amorphous FeOOH. The biocompatibility tests of het-FeHA did not show any adverse effect and the sample disintegrated within one day when implanted in mice peritoneum. In conclusion, we developed implantable hyaluronan-based free-standing film with minimal swelling that can be resorbed quickly enough to avoid induction of foreign-body reaction.

Hyaluronan: A key player or just a bystander in skin photoaging?

Photoaged skin exhibits signs of inflammation, DNA damage and changes in morphology that are visible at the macroscopic and microscopic levels. Photoaging also affects the extracellular matrix (ECM) including hyaluronan (HA), the main polysaccharide component thereof. HA is a structurally simple but biologically complex molecule that serves as a water-retaining component and provides both a scaffold for a number of the proteins of the ECM and the ligand for cellular receptors. The study provides an overview of the literature concerning the changes in HA amount, size and metabolism, and the potential role of HA in photoaging. We also suggest novel HA contributions to photoaging based on our knowledge of the role of HA in other pathological processes, including the senescence and inflammation-triggered ECM reorganization. Moreover, we discuss potential direct or indirect intervention to mitigate photoaging that targets the hyaluronan metabolism, as well as supplementation.

Silver distribution in chronic wounds and the healing dynamics of chronic wounds treated with dressings containing silver and octenidine

Although silver is an efficient antimicrobial and is a widely used antiseptic in wound healing, previous studies have reported the cytotoxic in vitro effects of silver dressings. Moreover, few studies have addressed the distribution of silver in chronic wounds. The study compares the healing of chronic wounds treated with a standard-of-care silver dressing (Ag-CMC) and a dressing containing antiseptic octenidine (OCT-HA). Biopsies were taken from two wound areas before the commencement of treatment (baseline), after 2 weeks and after 6 weeks (the end of the study). We analyzed the histopathologic wound-healing score, silver distribution, and expression of selected genes. The wound-healing score improved significantly in the wounded area treated with OCT-HA after 2 weeks compared to the baseline and the Ag-CMC. The Ag-CMC wound areas improved after 6 weeks compared to the baseline. Moreover, collagen maturation and decreases in the granulocyte and macrophage counts were faster in the OCT-HA parts. Treatment with OCT-HA resulted in less wound slough. The silver, visualized via autometallography, penetrated approximately 2 mm into the wound tissue and associated around capillaries and ECM fibers, and was detected in phagocytes. The metallothionein gene expression was elevated in the Ag-CMC wound parts. This exploratory study determined the penetration of silver into human chronic wounds and changes in the distribution thereof during treatment. We observed that silver directly affects the cells in the wound and elevates the metallothionein gene expression. Octenidine and hyaluronan dressings provide a suitable alternative to silver and carboxymethyl cellulose dressings without supplying silver to the wound.

How the molecular weight affects the in vivo fate of exogenous hyaluronan delivered intravenously: A stable-isotope labelling strategy

There is inconsistent information regarding the size effects of exogenously given hyaluronan on its in vivo fate. The data are often biased by the poor quality of hyaluronan and non-ideal labelling strategies used for resolving exogenous/endogenous hyaluronan, which only monitor the label and not hyaluronan itself. To overcome these drawbacks and establish the pharmacokinetics of intravenous hyaluronan in relation to its Mw, 13C-labelled HA of five Mws from 13.6-1562 kDa was prepared and administered to mice at doses 25-50 mg kg-1. The elimination efficiency increased with decreasing Mw. Low Mw hyaluronan was rapidly eliminated as small hyaluronan fragments in urine, while high Mw hyaluronan exhibited saturable kinetics and complete metabolization within 48 h. All tested Mws exhibited a similar uptake by liver cells and metabolization into activated sugars. 13C-labelling combined with LC-MS provides an excellent approach to elucidating in vivo fate and biological activities of hyaluronan.

Anti-HA antibody does not detect hyaluronan

It is generally known that hyaluronic acid (HA) is a biocompatible and biodegradable glycosaminoglycan distributed widely throughout epithelial, connective and neural tissues. HA is one of the chief components of the extracellular matrix. Lack of immunogenicity is one of the biggest advantages of the therapeutic use of HA, but it also prevents the production of specific anti-HA antibodies. Contrary to this, there are still several studies performing HA detection by immunohistochemical or immunohistofluorescent method using an anti-HA antibody. Therefore, this short study discusses whether the anti-HA antibody is specific for HA. To verify the specificity of the HA staining the hyaluronidase treatment of histological samples was performed and the ability of anti-HA antibody and biotinylated HA binding protein (bHABP)-based probe to bind to their targets was evaluated. Additionally, the competitive binding assay with short HA oligosaccharides and subsequent histological staining was performed. Both assays showed that the anti-HA antibody is not sufficiently specific for HA and that the bHABP probe is a reliable method for HA detection in histological samples. The conclusion made by previous investigators based on using HA antibodies should be reevaluated and future use of anti-HA antibody should be avoided.

Composite Hemostatic Nonwoven Textiles Based on Hyaluronic Acid, Cellulose, and Etamsylate

The achievement of rapid hemostasis represents a long-term trend in hemostatic research. Specifically, composite materials are now the focus of attention, based on the given issues and required properties. In urology, different materials are used to achieve fast and effective hemostasis. Additionally, it is desirable to exert a positive influence on local tissue reaction. In this study, three nonwoven textiles prepared by a wet spinning method and based on a combination of hyaluronic acid with either oxidized cellulose or carboxymethyl cellulose, along with the addition of etamsylate, were introduced and assessed in vivo using the rat partial nephrectomy model. A significantly shorter time to hemostasis in seconds (p < 0.05), was attributed to the effect of the carboxymethyl cellulose material. The addition of etamsylate did not noticeably contribute to further hemostasis, but its application strengthened the structure and therefore significantly improved the effect on local changes, while also facilitating any manipulation by the surgeons. Specifically, the hyaluronic acid supported the tissue healing and regeneration, and ensured the favorable results of the histological analysis. Moreover, the prepared textiles proved their bioresorbability after a three-day period. In brief, the fabrics yielded favorable hemostatic activity, bioresorbability, non-irritability, and had a beneficial effect on the tissue repair.

In vitro investigation of hyaluronan-based polymeric micelles for drug delivery into the skin: The internalization pathway

In our previous research, we concluded that polymeric micelles based on hyaluronic acid are able to penetrate into the deeper layers of skin tissue. The aim of this work was to characterize the mechanisms involved in the uptake by skin cells, which is important for understanding the influence of the carrier composition on the drug penetration. To reach this goal, we used micelles encapsulating curcumin made of oleyl-hyaluronan (HAC18:1) and hexyl-hyaluronan (HAC6) covalently linked with fluorescent Nile Blue. This labeling enabled us to track the micelle-forming derivative and also micelle payload into the keratinocytes and fibroblasts by fluorescent microscopy and flow cytometry. The regulation of both the passive and active cellular uptake was used to determine the mechanism of micelle internalization. Furthermore, the changes of membrane fluidity were measured for these derivatives by FRAP. Using these methods we concluded that carriers entered the cells using both active and passive transport. Passive transport was facilitated by the affinity of the carrier to the cell membrane, especially in the case of HAC18:1 carrier, which changed significantly the membrane fluidity. The active transport was dependent on cell type, but mainly driven by the clathrin-mediated endocytosis and macropinocytosis. Surprisingly, the main HA receptor, CD44, was not involved in the uptake. We can conclude that these carrier systems could be used for the local transport of active substances or hydrophobic drugs into the skin cells using the advantage of passive transport of oleyl-HA derivative.

An Effective Translation: The Development of Hyaluronan-Based Medical Products From the Physicochemical, and Preclinical Aspects

This review shows the steps toward material selection focalized on the design and development of medical devices based on hyaluronan (HA). The selection is based on chemical and mechanical properties, biocompatibility, sterilization, safety, and scale-up costs. These facts play a vital role in the industrialization process. Approved medical devices containing-HA are illustrated to identify key parameters. The first part of this work involves the steps toward a complete characterization of chemical and mechanical aspects, reproducibility of the processes and scale up. In a second stage, we aimed to describe the preclinical in vitro and in vivo assays and selected examples of clinical trials. Furthermore, it is important to keep in mind the regulatory affairs during the research and development (R&D) using standardization (ISO standards) to achieve the main goal, which is the functionality and safety of the final device. To keep reproducible experimental data to prepare an efficient master file for the device, based on quality and recorded manufacturing data, and a rigorous R&D process may help toward clinical translation. A strong debate is still going on because the denominated basic research in HA field does not pay attention to the purity and quality of the raw materials used during the development. So that, to achieve the next generation of devices is needed to overcome the limitations of state of art in terms of efficacy, biodegradability, and non-toxicity.

Absence of differences among low, middle, and high molecular weight hyaluronan in activating murine immune cells in vitro

Hyaluronan (HA) effects on immune response are suggested to be dependent on HA molecular weight (MW), as low MW HA should activate immune cells in contrast to high MW HA. However, some current studies do not support this conception and emphasize the importance of the form of preparation of HA, particularly with respect to its purity and origin. We compared the activation of mouse immune cells by HA samples (100kDa, 500kDa, and 997kDa) prepared from HA originating from rooster comb, and HA samples (71kDa, 500kDa, and 1000kDa) prepared from pharmacological grade HA originating from Streptococcus equi. Interestingly, in contrast to established theory, only middle and high MW HA originating from rooster comb induced the production of tumor necrosis factor-α by macrophages and in whole blood. Further, all tested preparations of HA failed to induce the expression of inducible nitric oxide synthase, the production of nitric oxide, or the expression of cyclooxygenase 2 in macrophages and splenocytes. Importantly, all HA samples originating from rooster comb were found to be contaminated by endotoxin (up to 1.23EU/ml). Hence, low MW HA did not reveal itself to have significantly higher immunostimulatory activity compared to HA of higher MW.

Hyaluronan polymeric micelles for topical drug delivery

Nanosized materials offer promising strategy for topical drug delivery due to their enhancing effect on drug percutaneous transport across the stratum corneum barrier. In this work, polymeric micelles made from hydrophobized hyaluronic acid (HA) were probed for skin delivery. Compared to non-polymeric micelle solutions containing similar drug amount, in vitro skin penetration analysis indicated 3 times larger deposition of drug in the epidermis and 6 times larger drug deposition in the dermis after 5h of topical treatment in Franz diffusion cells. The drug deposition was further increased with prolonged time of topical treatment. Laser confocal microscopy revealed the accumulation of both, the HA forming the vehicle and the payload, in the epidermis and dermis. Although fluorescent labeling of the HA would suggest co-transport of the HA and the drug, loading FRET pair dyes in the micellar core clearly demonstrated gradual micelle disruption with increasing skin depth. Transcellular penetration was the predominant pathway for the loaded drug. The HA polymeric micelles also demonstrated increased bioactivity of loaded compound in vitro and in vivo. In addition, the loaded micelles were found to be stable in cream formulations and thus they have great potential for topical applications for cosmetic and pharmaceutical purposes.

Paclitaxel isomerisation in polymeric micelles based on hydrophobized hyaluronic acid

Physical and chemical structure of paclitaxel (PTX) was studied after its incorporation into polymeric micelles made of hyaluronic acid (HA) (Mw=15 kDa) grafted with C6 or C18:1 acyl chains. PTX was physically incorporated into the micellar core by solvent evaporation technique. Maximum loading capacity for HAC6 and HAC18:1 was determined to be 2 and 14 wt.%, respectively. The loading efficiency was higher for HAC18:1 and reached 70%. Independently of the derivative, loaded HA micelles had spherical size of approximately 60-80 nm and demonstrated slow and sustained release of PTX in vitro. PTX largely changed its form from crystalline to amorphous after its incorporation into the micelle's interior. This transformation increased PTX sensitivity towards stressing conditions, mainly to UV light exposure, during which the structure of amorphous PTX isomerized and formed C3C11 bond within its structure. In vitro cytotoxicity assay revealed that polymeric micelles loaded with PTX isomer had higher cytotoxic effect to normal human dermal fibroblasts (NHDF) and human colon carcinoma cells (HCT-116) than the same micelles loaded with non-isomerized PTX. Further observation indicated that PTX isomer influenced in different ways cell morphology and markers of cell cycle. Taken together, PTX isomer loaded in nanocarrier systems may have improved anticancer activity in vivo than pure PTX.