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PubMed1999

New strategy for chemical modification of hyaluronic acid: preparation of functionalized derivatives and their use in the formation of novel biocompatible hydrogels.

Biodegradable materials for spatially and temporally controlled delivery of bioactive agents such as drugs, growth factors, or cytokines are key to facilitating tissue repair. We have developed a versatile method for chemical crosslinking high-molecular-weight hyaluronic acid under physiological conditions yielding biocompatible and biodegradable hydrogels. The method is based on the introduction of functional groups onto hyaluronic acid by formation of an active ester at the carboxylate of the glucuronic acid moiety and subsequent substitution with a side chain containing a nucleophilic group on one end and a (protected) functional group on the other. We have formed hyaluronic acid with amino or aldehyde functionality, and subsequently hydrogels with these hyaluronic acid derivatives and bifunctional crosslinkers or mixtures of the hyaluronic acid derivatives carrying different functionalities using active ester- or aldehyde-mediated reactions. Size analysis of the hyaluronic acid derivatives showed that the chemical modification did not lead to fragmentation of the polysaccharide. Hydrogels formed with hyaluronic acid derivatized to a varying degree and crosslinked with low- or high-molecular-weight crosslinkers were evaluated for biodegradability by digestion with hyaluronidase and for biocompatibility and ectopic bone formation by subcutaneous implantation in rats. Several hydrogel formulations showed excellent cell infiltration and chondro-osseous differentiation when loaded with bone morphogenetic protein-2 (BMP-2). Synergistic action of insulin-like growth factor-1 with BMP-2 promoted cartilage formation in this model, while addition of transforming growth factor-beta and BMP-2 led to rapid replacement of the matrix by bone.

Animals↗

PubMed2003

Quantification of hyaluronic acid fragments in pharmaceutical formulations using LC-ESI-MS.

Three different hyaluronic acid fragment preparations (HAF) derived from hyaluronic acid (HA) by hyaluronate lyase digestion have been investigated. The amount of these fragment mixtures in pharmaceutical formulations was determined by liquid chromatography-electrospray tandem mass spectrometry (LC/MS/MS). HAF analysis was performed in less than 8 min using a Nucleosil 100-7 C2 column. Based on the assumption that the mass distribution is kept constant, which is confirmed by the calibration results, quantification can be carried out relating to the most intense fragments. For that purpose, the ratios of the peak areas of product ions of m/z=378 (tetramer, hexamer, octamer) to the peak area of m/z=83 ([2xmaltose-H(+)], internal standard) were calculated. Calibration was done for each HAF and good linearity from 5 to 80 microg/ml has been shown. To evaluate the molecular weight distribution of the fragment preparations used in this approach MALDI-TOF, mass spectra have been collected.

Gas Chromatography-Mass Spectrometry↗

PubMed1984

Leucine metabolism as a source of acetate in the synthesis of hyaluronic acid.

Synovial fibroblasts were incubated in nutrient medium with either L-[U-14C]leucine or L-[4,5-3H]leucine to reveal peptides associated with hyaluronic acid. Isotope was found in hyaluronic acid extracted from culture medium by repeated density gradient ultracentrifugation, but 76-98% of the labelled hyaluronic acid fraction was recovered as oligosaccharide by Sephadex G-25 gel chromatography after digestion with protease-free staphylococcal hyaluronidase (EC 4.2.99.1). Radioactivity in acid digests of the oligosaccharide fractions (i) was volatile, (ii) separated similarly to acetate in Biogel P2 chromatography, and (iii) was identified as acetate by melting point after conjugation as a p-phenylphenacyl ester crystallized to constant specific activity. The synovial fibroblast thus possesses metabolic pathways for complete transformation of leucine to acetylCoA, which operate freely in adequate nutrient medium and are a significant source of acetyl groups in hyaluronic acid synthesis.

Acetates↗

PubMed2002

The role of hyaluronic acid, chitosan, and calcium sulfate and their combined effect on early bony consolidation in distraction osteogenesis of a canine model.

The purpose of this project was to study the effect of hyaluronic acid, calcium sulfate, and chitosan on early bony consolidation in distraction osteogenesis of a canine model. Sixteen dogs were used for this study. The lateral surface of the mandibular body was exposed in the subperiosteal plane, and the vertical osteotomy on the mandibular body was extended downward. An external distraction device was applied to the mandibular body, and the mandibular distraction was started 5 days after the operation at a rate of 1 mm/d up to a 10-mm distraction. The experimental group was then divided into a control group, chitosan group, hyaluronic acid group, calcium sulfate combined with hyaluronic acid group, and calcium sulfate combined with chitosan group, depending on the type of implantation material in the distracted area. After completing the distraction, implantation material was injected into the distracted area, although no material was implanted into the distracted area of the control group. After implanting the materials, the distraction device was left in place for 6 weeks to allow for bony consolidation. Four dogs were allocated to each group. Two dogs in each group (total of 8 dogs) were killed 3 weeks after implantation of the material, and the other 8 dogs were killed after 6 weeks. New bone was generated in the distracted zone of all groups. In the calcium sulfate combined with chitosan group and calcium sulfate combined with hyaluronic acid group, the formation of active woven bone was observed throughout the distracted zone. Moreover, the new bone seemed to be nearly normal cortical bone at 6 weeks after implantation. In the chitosan group and hyaluronic acid group, the development of new bone was observed in the distracted zone at 6 weeks. The amount was less than that in the calcium sulfate combined with hyaluronic acid group and calcium sulfate combined with chitosan group. These findings suggest that calcium sulfate and its combined materials seem to be quite effective in early bony consolidation in distraction osteogenesis.

Animals↗

PubMed1992

Kinetic studies on activation of peptide bond formation by hyaluronic acid.

1. In this study, a cell-free system derived from Escherichia coli has been used in order to examine in detail the effect of hyaluronic acid on peptide bond formation with the aid of puromycin reaction. 2. This reaction is activated by hyaluronic acid. 3. The degree of activation of peptide bond formation depends on the molecular size of hyaluronic acid. 4. The kinetic analysis revealed that the hyaluronic acid acts as a mixed-type nonessential activator. 5. The presence of hyaluronic acid improves about 9-fold the activity status of ternary complex as it can be calculated by k3/k5 ratio.

Escherichia coli↗

PubMedDate not supplied

Increase of cellular hyaluronic acid synthesis following continuous exposure of cultured human fibroblasts (WI-38) to hydrocortisone.

Continuous (long-term) exposure of cultured normal (diploid) human fibroblasts (WI-38) to hydrocortisone (1.4 X 10(-7) M) resulted, as originally described by Macieira-Coelho (1966) and Cristofalo (1970), in a stimulation of proliferative activity and an increase of population doublings. Stimulation of DNA-synthesis by hydrocortisone, as measured by 3H-thymidine incorporation, required the presence of serum in the culture medium. Analysis of the cellular glycosaminoglycan (GAG) pattern, as measured by 14C-glucosamine incorporation into the various GAG types (hyaluronic acid, heparan sulfate, chondroitin sulfate, dermatan sulfate) revealed a significant increase of cell-bound hyaluronic acid (it appears to be predominantly located at the cell surface or pericellular, since it is removable to a large extent by trypsin treatment), while the distribution pattern of sulfated GAGs did not exhibit a significant change. This increase of cellular hyaluronic acid synthesis was regarded largely as an adaptive response to hydrocortisone, since its removal from the culture medium of hydrocortisone pretreated cultures resulted in a significant decrease of cellular hyaluronic acid. Possible functions of cell-bound hyaluronic acid were suggested in regard to cell surface properties (cell-cell and cell-substratum adhesion; migratory activity). Thus, decreased adhesiveness (by elevated cellular hyaluronic acid) might be a decisive factor for the well-known increase in cell saturation density caused by hydrocortisone. Generally, the present findings support a concept (Sluke et al., 1981; Schachtschabel and Sluke, 1984) that an increase of cellular hyaluronic acid synthesis is "growth-favorable", which is in line with previous findings of a decrease of hyaluronic acid synthesis by growth restriction in the course of in vitro ageing (Sluke et al., 1981).

Cell Adhesion↗

PubMed1990

Hyaluronic acid prevents oxygen free-radical damage to granulation tissue: a study in rats.

Oxygen free-radicals are known to impair wound healing after ischaemia-reperfusion or polymorphonuclear cell stimulation. Furthermore, they reduce the breaking strength of all recent wounds and might be a cause of wound leakage. This study was performed to evaluate whether or not hyaluronic acid can reduce the risk of wound impairment caused by free-radicals, in rats with abdominal sepsis, polymorphonuclear cell stimulation or cytochrome C function derangement produced by xenobiotics. Male Sprague-Dawley rats with open wounds received phenazine methosulfate or zimosan, or had abdominal sepsis to induce oxygen free-radical generation. There were three groups of treatment: hyaluronic acid cream, hyaluronic acid ethyl ester gel, and placebo. The reduction in wound size was measured from the 1st to the 11th postoperative day; biopsies were taken for histological evaluation. Every other day, a gentle debridement was performed in all the groups of animals. We found that hyaluronic acid and its ethyl ester derivative significantly improved the wound healing of rats subjected to an increased generation of oxygen free-radicals. It remains to be established whether or not hyaluronic acid acts as a scavenger of free-radicals.

Animals↗

PubMed1986

Hyaluronic acid bonded to cell culture surfaces inhibits the program of myogenesis.

Primary isolates of chick leg muscle myoblasts cultured on hyaluronic acid substrates have been examined by transmission electron microscopy for evidence of myoblast fusion and subsequent differentiation. Even though these cells form close contacts, no evidence of multinucleated myotubes is found in these cultures. Two-dimensional SDS-polyacrylamide gel electrophoresis shows that the muscle macromolecular biosynthetic program is not initiated in these hyaluronic acid fusion-blocked cells. Further, these fusion-blocked myoblasts continue replicating while cultured on hyaluronic acid surfaces. The inhibition of both fusion and the myogenic expressional program is reversed by replating these myoblasts onto a denatured collagen (gelatin) substrate; both the synthesis of muscle-specific proteins and the formation of multinucleated myotubes are observed when these subcultured cells are introduced onto gelatin substrates. These observations indicate that the hyaluronic acid inhibition of fusion is not permanent and is manifested in a way different from other fusion blockers in that hyaluronic acid inhibits both fusion and the myogenic expressional program.

Actin Cytoskeleton↗

PubMed1995

Hyaluronic acid synthesis operon (has) expression in group A streptococci.

The has operon is composed of three genes, hasA, hasB, and hasC that encode hyaluronate synthase, UDP-glucose dehydrogenase, and presumptively UDP-glucose pyrophosphorylase, respectively. Expression of the has operon was shown to be required for the synthesis of the hyaluronic acid capsule in group A streptococci. Previous studies indicated that some group A and group C streptococcal strains produce the hyaluronic acid capsule, while others do not. In addition, it was observed that encapsulated strains cultured in stationary phase of growth lose the hyaluronic acid capsule. Therefore, the molecular mechanisms controlling the expression of the hyaluronic acid capsule in group A streptococci was investigated. In this study, it was determined that all encapsulated and unencapsulated strains of group A streptococci as well as encapsulated group C streptococci analyzed possess the has operon locus. The acapsular phenotype was accounted for by the absence of hyaluronate synthase activity in the membrane and not the production of extracellular hyaluronidase. A has operon mRNA transcript was not expressed by unencapsulated strains of group A streptococci, whereas encapsulated strains of group A streptococci grown to mid to late exponential phase produced the hyaluronate capsule, as well as has operon mRNA. However, as the streptococci entered the stationary phase of growth, they became acapsular and this was concomitant with the loss of has operon mRNA transcript. These results were confirmed by primer extension analyses of RNA isolated from encapsulated and unencapsulated strains of group A streptococci as well as RNA prepared from encapsulated strains cultured in exponential and stationary phases of growth. Thus, the loss of has operon mRNA in unencapsulated group A streptococci, as well as growth phase regulation occurs at the previously mapped has operon promoter. These data suggested that the synthesis of the hyaluronic acid capsule for group A streptococci may be controlled by transcriptional mechanisms.

Bacterial Capsules↗

PubMed1978

The synovial fluid hyaluronic acid in rheumatoid arthritis.

The intrinsic viscosity of hyaluronic acid in synovial fluid decreases significatively in mild and severe arthritis (24% and 37% respectively). Variation in hyaluronic acid concentration parallels the above results. Chondroitin-6-sulfate can be detected in about 30% of the arthritic fluids.

Adolescent↗

PubMedDate not supplied

3% diclofenac in 2.5% hyaluronic acid (Solaraze) does not induce photosensitivity or phototoxicity alone or in combination with sunscreens.

Topical treatment with 3% diclofenac in 2.5% hyaluronic acid (Solaraze) has been extensively documented for the treatment of actinic keratoses (AK). Since sun protection is a vital part of AK management, two Phase IV studies were carried out to investigate the phototoxicity and photosensitisation potential of 3% diclofenac in 2.5% hyaluronic acid in combination with sunscreens. Patches of 3% diclofenac in 2.5% hyaluronic acid and control were applied under occlusion to the backs of healthy volunteers aged 18-65. In the phototoxicity study (n = 32), a single application followed by administration of the sunscreens and exposition with ultraviolet (UV) were done, whereas in the photosensitisation study, application was repeated twice weekly for three weeks, then once after a two-week rest phase. The erythema reaction was recorded, together with other local skin reactions. In both analyses, areas treated with 3% diclofenac in 2.5% hyaluronic acid in combination with sunscreens had the lowest incidence of erythema reactions, indicating that it was well tolerated when used in conjunction with sunscreen products, and with exposure to UV irradiation. The results showed that no phototoxic or photosensitisation reactions occurred with 3% diclofenac in 2.5% hyaluronic acid, either alone or in combination with sunscreens.

Adjuvants, Immunologic↗

PubMed1987

Liquid chromatographic assay for constituent disaccharides of hyaluronic acid and chondroitin sulphate isomers.

An improved high-performance liquid chromatographic (HPLC) method for unsaturated disaccharides prepared from hyaluronic acid and various chondroitin sulphate and dermatan sulphate isomers was developed, which involves an ion-exchange resin prepared from a sulphonated styrene-divinylbenzene copolymer. The retention times of the individual unsaturated disaccharides were unique and reproducible, the disaccharides appearing in the following order: unsaturated non-sulphated disaccharide derived from hyaluronic acid, then unsaturated 6-sulphated, non-sulphated and 4-sulphated disaccharides from chondroitin sulphate isomers. Unsaturated disulphated disaccharide G had a much shorter retention time than the unsaturated non-sulphated disaccharide derived from hyaluronic acid. The contents of these individual unsaturated disaccharides could be determined with similar sensitivities on the basis of their ultraviolet absorbance. Selective and unique retention times and good resolutions were found for various unsaturated disulphated and trisulphated disaccharides. The proposed method can be used to determine various chondroitin sulphate and dermatan sulphate isomers in addition to hyaluronic acid in amounts as small as 100 ng to 8 micrograms. The practicality of this method was verified by its application to the separation and determination of the different types of chondroitin sulphate and dermatan sulphate isomers derived from human arteries in the presence of appreciable amounts of hyaluronic acid.

Arteries↗

PubMed2004

A study on a chitosan-gelatin-hyaluronic acid scaffold as artificial skin in vitro and its tissue engineering applications.

Chitosan-gelatin-hyaluronic acid scaffolds for tissue regeneration were fabricated by freezing and lyophilizing methods. The scaffolds showed a higher water uptake and retention abilities than chitosan-gelatin scaffolds did. Fibroblasts cultured in chitosan-gelatin-hyaluronic acid scaffolds grew and proliferated well, and they exhibited a strong viability. Keratinocytes were co-cultured with fibroblasts in chitosan-gelatin-hyaluronic acid scaffolds to construct an artificial bilayer skin in vitro. The artificial skin obtained was flexible and had good mechanical properties. The data from this study suggested that chitosan-gelatin-hyaluronic acid scaffolds are suitable for preparing a bilayer skin substitute.

Biocompatible Materials↗

PubMed2004

Serum hyaluronic acid during lamivudine treatment in chronic hepatitis B.

PURPOSE: We address the question whether lamivudine treatment modulates serum concentrations of hyaluronic acid and whether the pre-treatment HA level can give the information about the presumptive result of treatment and whether HA level evaluation can be useful in monitoring the antiviral therapy in chronic hepatitis B. MATERIAL AND METHODS: Forty-nine patients, 31 man, aged 40 +/- 2.5 years were treated with 100 mg lamivudine per day for 48 weeks. Serum hyaluronic acid level was determined using enzyme-linked binding protein commercial assay (Corgenix Inc., USA). RESULTS: The mean HA pre-treatment levels were higher than among controls (69.6 +/- 11.6 ng/ml vs 36.5 +/- 7.6 ng/ml, mean +/- SEM) and correlated with AST activity, p = 0.002; GGT activity, p = 0.006; ALP activity p < 0.001; prothrombin time, p = 0.01; and peripheral blood platelets count, p = 0.001 but did not correlated with ALT activity. The pre-treatment HA concentration correlated also with interlobular necroinflammatory activity score, p = 0.049 and with fibrosis score, p = 0.026, according to Scheuer classification. The mean HA levels decreased gradually during lamivudine treatment, up to levels lover than among controls (26.3 +/- 5.7 ng/ml). There were not significant differences in pre-treatment levels observed between patients neither with HBs seroconversion versus those without it, nor between patients with HBe seroconversion versus those without it and among patients with normalization of ALT activity versus ones without it. CONCLUSIONS: Serum hyaluronic acid level decreases during lamivudine treatment both in patients with HBeAg seroconversion and without it; serum hyaluronic acid pretherapy levels correlate with necroinflammatory lobular activity score and with liver fibrosis score; serum hyaluronic acid is of no predictive value for lamivudine therapy response; serum hyaluronan may be valuable complementary marker in chronically HBV infected patients.

Adult↗

PubMed1991

Effect of hyaluronic acid on postoperative intraperitoneal adhesion formation in the rat model.

OBJECTIVE: The aim of this study was to determine the effectiveness of hyaluronic acid solution in preventing intraperitoneal (IP) adhesions. DESIGN AND SETTING: The study design was prospective, randomized and blinded and involved 83 rats. INTERVENTIONS: Measured serosal injury was inflicted using a CO2 laser on the right uterine horn of the rat. Animals randomized to groups 1 and 2 received either 0.4% hyaluronic acid or its diluent phosphate-buffered saline (PBS) intraperitoneally before and after the injury. In groups 3 and 4, the same solutions were used only after the injury. Postoperative adhesions were assessed at second-look laparotomy. Histologic assessment of the fresh laser injury was carried out on uteri pretreated with hyaluronic acid, PBS, or nothing. MAIN OUTCOME: Pretreatment with hyaluronic acid was associated with a significant reduction in postoperative adhesions and a significantly decreased crater depth. CONCLUSIONS: Hyaluronic acid appears to reduce postoperative IP adhesion formation by coating the serosal surfaces and decreasing the extent of initial tissue injury.

Animals↗

PubMed2005

A new experimental model of glaucoma in rats through intracameral injections of hyaluronic acid.

An experimental model of pressure-induced optic nerve damage would greatly facilitate the understanding of the cellular events leading to ganglion cell death, and how they are influenced by intraocular pressure and other risk factors associated to glaucoma. The aim of the present report was to study the effect of a long-term increase of intraocular pressure in rats induced by intracameral injections of hyaluronic acid with respect to electroretinographic activity and retinal and optic nerve histology. For this purpose, hyaluronic acid was injected weekly in the rat anterior chamber of one eye, whereas the contralateral eye was injected with saline solution. The results showed a significant decrease of oscillatory potentials and a- and b-wave amplitude of the scotopic electroretinogram after 3 or 6 weeks of hyaluronic acid administration, respectively. These parameters were further reduced after 10 weeks of treatment with hyaluronic acid. No significant changes in anterior chamber angle structures from hyaluronic acid- and vehicle-injected eyes were observed, whereas a significant loss of ganglion cell layer cells and of optic nerve axons were detected in animals that received hyaluronic acid for 10 weeks, as compared to eyes injected with saline solution. In summary, present results indicate that the chronic administration of hyaluronic acid induced a significant decrease in the electroretinographic activity and histological changes in the retina and optic nerve that seem consistent with some features of chronic open-angle glaucoma. Therefore, this could be an experimental model to study the cellular mechanisms by which elevated intraocular pressure damages the optic nerve and the retina.

Animals↗

PubMedDate not supplied

Effects of hyaluronic acid in culture and cytochalasin B treatment before freezing on survival of cryopreserved bovine embryos produced in vitro.

One limitation to the widespread use of in vitro-produced embryos in cattle is their poor survival following cryopreservation. Two approaches for enhancing survival of in vitro-produced bovine embryos following cryopreservation were evaluated: culture in the presence of hyaluronic acid and alterations in the cytoskeleton through cytochalasin B treatment. The experiment was a 2 x 2 factorial design to test main effects of hyaluronic acid added to culture at day 5 after insemination (+ or -) and cryopreservation treatment (control or cytochalasin B). Embryos used for cryopreservation were blastocysts and expanded blastocysts harvested on day 7 after insemination. Cytochalasin B increased the percent of embryos that re-expanded (P < 0.0001) and that hatched following thawing (P < 0.05). The hatching percent was 29.6% for embryos treated with cytochalasin B versus 9.1% for control embryos. There was no significant effect of hyaluronic acid on survival although there was a tendency for embryos cultured with hyaluronic acid to have higher percent hatching if not treated with cytochalasin B (12.7% for hyaluronic acid versus 4.5% for control; hyaluronic acid x cytochalasin B interaction; P = 0.09). In conclusion, cytochalasin B treatment before freezing improved cryosurvival of bovine embryos produced in vitro. Such a treatment could be incorporated into methods for cryopreservation of bovine embryos provided post-transfer survival is adequate. In contrast, culture with hyaluronic acid was of minimal benefit- the increased cryosurvival in the absence of cytochalasin B was not sufficient to allow an adequate number of embryos to survive.

Animals↗

PubMed2003

The neurotoxicity of epidural hyaluronic acid in rabbits: a light and electron microscopic examination.

UNLABELLED: Because hyaluronic acid (HA) has an antiinflammatory effect and prevents and/or reduces tissue adhesion, we believed it possible that epidurally-administered HA during epidural adhesiolysis procedures could alleviate pain in patients with chronic lower back pain. Therefore, we performed this pre-clinical trial evaluation of epidurally-administered HA neurotoxicity by light microscopy (LM) and electron microscopy (EM) in rabbits. Twenty rabbits were randomly divided into two groups, a normal saline (NS) group (n = 10) and a HA group (n = 10). Saline (0.2 mL/kg of 0.9% solution) and the same volume of HA were injected into the epidural space. No rabbits showed any sensory-motor or behavior change during the 3-wk period, except for one rabbit in the NS group that showed decreased appetite, activity, and weight loss. By LM, two rabbits in the NS group showed abnormal findings considered to be the result of trauma and infection associated with epidural catheterization. EM findings showed no significant neurotoxic findings in either group. In conclusion, epidurally-administered HA did not cause neurotoxicity in rabbits. IMPLICATIONS: We performed a pre-clinical trial evaluation on the neurotoxicity of hyaluronic acid administered epidurally by light microscopy and electron microscopy in rabbits. Epidurally-administered hyaluronic acid did not produce any sign of neurotoxicity in rabbits.

Animals↗