Anti-inflammatory activity of superoxide dismutase conjugated with sodium hyaluronate

Hyaluronan and cardiac regeneration

Hyaluronan (HA) is abundantly expressed in several human tissues and a variety of roles for HA has been highlighted. Particularly relevant for tissue repair, HA is actively produced during tissue injury, as widely evidenced in wound healing investigations. In the heart HA is involved in physiological functions, such as cardiac development during embryogenesis, and in pathological conditions including atherosclerosis and myocardial infarction. Moreover, owing to its relevant biological properties, HA has been widely used as a biomaterial for heart regeneration after a myocardial infarction. Indeed, HA and its derivatives are biodegradable and biocompatible, promote faster healing of injured tissues, and support cells in relevant processes including survival, proliferation, and differentiation. Injectable HA-based therapies for cardiovascular disease are gaining growing attention because of the benefits obtained in preclinical models of myocardial infarction. HA-based hydrogels, especially as a vehicle for stem cells, have been demonstrated to improve the process of cardiac repair by stimulating angiogenesis, reducing inflammation, and supporting local and grafted cells in their reparative functions. Solid-state HA-based scaffolds have been also investigated to produce constructs hosting mesenchymal stem cells or endothelial progenitor cells to be transplanted onto the infarcted surface of the heart. Finally, applying an ex-vivo mechanical stretching, stem cells grown in HA-based 3D scaffolds can further increase extracellular matrix production and proneness to differentiate into muscle phenotypes, thus suggesting a potential strategy to create a suitable engineered myocardial tissue for cardiac regeneration.

Recovery of peripheral nerve with massive loss defect by tissue engineered guiding regenerative gel

OBJECTIVE

Guiding Regeneration Gel (GRG) was developed in response to the clinical need of improving treatment for peripheral nerve injuries and helping patients regenerate massive regional losses in peripheral nerves. The efficacy of GRG based on tissue engineering technology for the treatment of complete peripheral nerve injury with significant loss defect was investigated.

BACKGROUND

Many severe peripheral nerve injuries can only be treated through surgical reconstructive procedures. Such procedures are challenging, since functional recovery is slow and can be unsatisfactory. One of the most promising solutions already in clinical practice is synthetic nerve conduits connecting the ends of damaged nerve supporting nerve regeneration. However, this solution still does not enable recovery of massive nerve loss defect. The proposed technology is a biocompatible and biodegradable gel enhancing axonal growth and nerve regeneration. It is composed of a complex of substances comprising transparent, highly viscous gel resembling the extracellular matrix that is almost impermeable to liquids and gasses, flexible, elastic, malleable, and adaptable to various shapes and formats. Preclinical study on rat model of peripheral nerve injury showed that GRG enhanced nerve regeneration when placed in nerve conduits, enabling recovery of massive nerve loss, previously unbridgeable, and enabled nerve regeneration at least as good as with autologous nerve graft "gold standard" treatment.

Hyaluronan and synovial joint: function, distribution and healing

Synovial fluid is a viscous solution found in the cavities of synovial joints. The principal role of synovial fluid is to reduce friction between the articular cartilages of synovial joints during movement. The presence of high molar mass hyaluronan (HA) in this fluid gives it the required viscosity for its function as lubricant solution. Inflammation oxidation stress enhances normal degradation of hyaluronan causing several diseases related to joints. This review describes hyaluronan properties and distribution, applications and its function in synovial joints, with short review for using thiol compounds as antioxidants preventing HA degradations under inflammation conditions.

Hyaluronic acid: evaluation as a potential delivery vehicle for vitronectin:growth factor complexes in wound healing applications

We have previously reported that novel vitronectin:growth factor (VN:GF) complexes significantly increase re-epithelialization in a porcine deep dermal partial-thickness burn model. However, the potential exists to further enhance the healing response through combination with an appropriate delivery vehicle which facilitates sustained local release and reduced doses of VN:GF complexes. Hyaluronic acid (HA), an abundant constituent of the interstitium, is known to function as a reservoir for growth factors and other bioactive species. The physicochemical properties of HA confer it with an ability to sustain elevated pericellular concentrations of these species. This has been proposed to arise via HA prolonging interactions of the bioactive species with cell surface receptors and/or protecting them from degradation. In view of this, the potential of HA to facilitate the topical delivery of VN:GF complexes was evaluated. Two-dimensional (2D) monolayer cell cultures and 3D de-epidermised dermis (DED) human skin equivalent (HSE) models were used to test skin cell responses to HA and VN:GF complexes. Our 2D studies revealed that VN:GF complexes and HA stimulate the proliferation of human fibroblasts but not keratinocytes. Experiments in our 3D DED-HSE models showed that VN:GF complexes, both alone and in conjunction with HA, led to enhanced development of both the proliferative and differentiating layers in the DED-HSE models. However, there was no significant difference between the thicknesses of the epidermis treated with VN:GF complexes alone and VN:GF complexes together with HA. While the addition of HA did not enhance all the cellular responses to VN:GF complexes examined, it was not inhibitory, and may confer other advantages related to enhanced absorption and transport that could be beneficial in delivery of the VN:GF complexes to wounds.

The GPCR modulator protein RAMP2 is essential for angiogenesis and vascular integrity

Adrenomedullin (AM) is a peptide involved both in the pathogenesis of cardiovascular diseases and in circulatory homeostasis. The high-affinity AM receptor is composed of receptor activity-modifying protein 2 or 3 (RAMP2 or -3) and the GPCR calcitonin receptor-like receptor. Testing our hypothesis that RAMP2 is a key determinant of the effects of AM on the vasculature, we generated and analyzed mice lacking RAMP2. Similar to AM-/- embryos, RAMP2-/- embryos died in utero at midgestation due to vascular fragility that led to severe edema and hemorrhage. Vascular ECs in RAMP2-/- embryos were severely deformed and detached from the basement membrane. In addition, the abnormally thin arterial walls of these mice had a severe disruption of their typically multilayer structure. Expression of tight junction, adherence junction, and basement membrane molecules by ECs was diminished in RAMP2-/- embryos, leading to paracellular leakage and likely contributing to the severe edema observed. In adult RAMP2+/- mice, reduced RAMP2 expression led to vascular hyperpermeability and impaired neovascularization. Conversely, ECs overexpressing RAMP2 had enhanced capillary formation, firmer tight junctions, and reduced vascular permeability. Our findings in human cells and in mice demonstrate that RAMP2 is a key determinant of the effects of AM on the vasculature and is essential for angiogenesis and vascular integrity.

Hyaluronan: pharmaceutical characterization and drug delivery

Hyaluronic acid (HA), is a polyanionic polysaccharide that consists of N-acetyl-D-glucosamine and beta-glucoronic acid. It is most frequently referred to as hyaluronan because it exists in vivo as a polyanion and not in the protonated acid form. HA is distributed widely in vertebrates and presents as a component of the cell coat of many strains of bacteria. Initially the main functions of HA were believed to be mechanical as it has a protective, structure stabilizing and shock-absorbing role in the body. However, more recently the role of HA in the mediation of physiological functions via interaction with binding proteins and cell surface receptors including morphogenesis, regeneration, wound healing, and tumor invasion, as well as in the dynamic regulation of such interactions on cell signaling and behavior has been documented. The unique viscoelastic nature of hyaluronan along with its biocompatibility and nonimmunogenicity has led to its use in a number of cosmetic, medical, and pharmaceutical applications. More recently, HA has been investigated as a drug delivery agent for ophthalmic, nasal, pulmonary, parenteral, and dermal routes. The purpose of our review is to describe the physical, chemical, and biological properties of native HA together with how it can be produced and assayed along with a detailed analysis of its medical and pharmaceutical applications.

Hyaluronic acid: a unique topical vehicle for the localized delivery of drugs to the skin

Hyaluronic acid (HA) is a naturally occurring polyanionic, polysaccharide that consists of N-acetyl-D-glucosamine and beta-glucoronic acid. It is present in the intercellular matrix of most vertebrate connective tissues especially skin where it has a protective, structure stabilizing and shock-absorbing role. The unique viscoelastic nature of HA along with its biocompatibility and non-immunogenicity has led to its use in a number of clinical applications, which include: the supplementation of joint fluid in arthritis; as a surgical aid in eye surgery; and to facilitate the healing and regeneration of surgical wounds. More recently, HA has been investigated as a drug delivery agent for various routes of administration, including ophthalmic, nasal, pulmonary, parenteral and topical. In fact, regulatory approval in the USA, Canada and Europe was granted recently for 3% diclofenac in 2.5% HA gel, Solaraze, for the topical treatment of actinic keratoses, which is the third most common skin complaint in the USA. The gel is well tolerated, safe and efficacious and provides an attractive, cost-effective alternative to cryoablation, curettage or dermabrasion, or treatment with 5-fluorouracil. The purpose of this review is to describe briefly the physical, chemical and biological properties of HA together with some details of its medical and pharmaceutical uses with emphasis on this more recent topical application.

Is intraarticular sodium hyaluronate injection an alternative treatment in patients with adhesive capsulitis?

The aim of this study was to compare the efficacy of sodium hyaluronate (SH) injection with the most common treatment methods, intraarticular steroid injection and physical therapy modalities in patients with adhesive capsulitis (AC). A total of 95 shoulders of 90 patients were included in the study and were randomized in four groups. The patients were treated with SH injection (group 1), triamsinolone acetonide (group 2) or physical therapy modalities (group 3). Group 4 patients were served as controls. Pain severity, passive ranges of motion and functional considerations were measured before, and 15 days and 3 months after the treatments. In all treatment groups, there were significant improvements at both the 15th day and third month in all parameters (for each, p<0.001). The passive abduction values on the 15th day was found significantly higher in group 3 when compared with group 1 and controls (for each, p<0.001). At the third month, the passive abduction values of the groups 2 and 3 were improved when compared with the control group (p<0.001). Constant score was higher in group 3 on 15th day when compared with group 1. At the third month, all treatment groups were improved significantly compared with control group (p<0.001). We provided the best results in physical therapy modalities applied group for AC treatment. However, we think that SH injection may be administered as an alternative treatment method.

Photo-control of the interaction between endothelial cells and photo-cation generatable water-soluble polymers

In this study photo-control of the non-biospecific interaction between endothelial cell membranes and photo-cation generatable water-soluble polymers were examined. The water-soluble polymers contained triphenylmethane leucohydroxide (malachite green) groups (contents: 0.4 and 1.6 mol%), which dissociate into triphenylmethyl cations and counter hydroxide ions upon ultraviolet light (UV) irradiation, and were prepared by free radical copolymerization of diphenyl(4-vinylphenyl)methane leucohydroxide and acrylamide. The nature and magnitude of the interaction was quantitatively assessed by direct luminescence measurement of the intracellular calcium ion concentration using a calcium-sensitive photoprotein, aequorin. When a PBS buffer of the photoreactive copolymers were added, prior to UV irradiation, to a PBS suspension of cultured bovine endothelial cells loaded with aequorin, no detectable elevation of Ca(2+) was measured. In contrast, cationic copolymers, derived from the photoreactive copolymers after UV irradiation at a wavelength of 290<lambda<410 nm, induced an immediate transient increase in the cytosolic free Ca(2+) concentration due to a Ca(2+) inflow from the extracellular space into the cells, which may be due to non-biospecific transmembrane stimulation. Longer UV irradiation exposures of the copolymers and higher concentrations of the polymers, with higher contents of the photodissociable group, resulted in more Ca(2+) inflow with little cellular damage. The photo-cation generatable copolymers developed here made possible to control the non-biospecific interaction with endothelial cell membranes by UV irradiation condition, and composition and amount of the copolymer.

Comparison of the antioxidant properties of wound dressing materials--carboxymethylcellulose, hyaluronan benzyl ester and hyaluronan, towards polymorphonuclear leukocyte-derived reactive oxygen species

In chronic wounds, factors are released which perpetuate inflammatory processes, including polymorphonuclear leukocyte (PMN)-derived reactive oxygen species (ROS), such as superoxide radical (O(2)*-) and hydroxyl radical (*OH) species. The glycosaminoglycan, hyaluronan, has established antioxidant properties towards ROS, although the antioxidant potential of wound dressing biomaterials, such as 75% benzyl esterified hyaluronan (BEHA) and carboxymethylcellulose (CMCH), are less characterised. This study compared the antioxidant properties of high and low molecular weight hyaluronan (HMWT HA and LMWT HA), BEHA and CMCH towards ROS, generated by stimulated PMN in vitro. The antioxidant capacities of each biomaterial were assessed by their inhibition of O(2)*- -induced cytochrome C reduction, generated via PMN stimulation by phorbol myristyl acetate (PMA); and their inhibition of *OH-induced 2-deoxy-D-ribose degradation, generated by PMA stimulated PMN in the presence of a ferric chloride-EDTA chelate. All biomaterials, except LMWT HA, possessed dose-dependent antioxidant properties against O(2)*-, BEHA having greatest antioxidant potential, followed by HMWT HA and CMCH. HMWT HA exhibited the highest dose-dependent antioxidant properties towards *OH, followed by BEHA and CMCH. LMWT HA demonstrated no antioxidant properties towards *OH. These antioxidant activities, particularly towards O(2)*-, may be beneficial in removing the initial source of ROS necessary for the secondary formation of *OH, implicated as a causal factor for the extensive metabolic alterations observed in chronic wounds.

Comparison of the antioxidant properties of HYAFF-11p75, AQUACEL and hyaluronan towards reactive oxygen species in vitro

In chronic wounds, a number of host factors are released which perpetuate the inflammatory process, including polymorphonuclear leukocyte (PMN)-derived reactive oxygen species (ROS), such as superoxide radical (O2*-) and hydroxyl radical (*OH) species. The glycosaminoglycan. hyaluronan, has been shown to act as an antioxidant towards ROS, although the potential for biomaterials, such as HYAFF -11p75 (the 75% benzyl ester of hyaluronan) and AQUACEL (carboxymethylcellulose), to act in this manner has yet to be elucidated. This study compared the antioxidant properties of high and low molecular weight hyaluronan (HMWT HA and LMWT HA), HYAFF -11p75, AQUACEL and an AQUACEL /hyaluronan composite (AQUACEL /HA) against O2*- and *OH. The antioxidant capacities of each material were assessed by their ability to inhibit cytochrome C reduction by O2*- fluxes, generated via the oxidation of hypoxanthine by xanthine oxidase, and their inhibition of 2-deoxy-D-ribose degradation by *OH fluxes, generated by the reaction of hydrogen peroxide (H2O2) and iron (Fe2+). All materials studied possessed dose dependent antioxidant properties towards O2*-, with HYAFF 11p75 having the greatest antioxidant potential towards these species, followed by AQUACEL, HMWT HA, AQUACEL /HA and LMWT HA. Only HMWT HA exhibited dose dependent antioxidant properties towards *OH at the fluxes examined. Gas chromatography/mass spectrometry analysis implied that ester bonds between the hyaluronan backbone and benzyl groups of HYAFF -11p75 are highly susceptible to O2*- hydrolysis, with the de-esterified benzyl alcohol being rapidly degraded in the presence of *OH. This data supports the hypothesis that HYAFF -11p75 has greater antioxidant capacity towards O2*-, due to the esterified benzyl groups providing alternative sites for O2*- attack other than the hyaluronan backbone of HYAFF -11p75 itself and explains the inability of HYAFF -11p75 to scavenge *OH, due to benzyl alcohol degradation by *OH. The antioxidant activities of these biomaterials, particularly HYAFF -11p75 and AQUACEL, towards O2*- could be beneficial, as the scavenging of PMN-derived O2*- may remove initial sources of O2*- and further prevent the secondary formation of *OH. These ROS are thought to be a primary causal factor for the extensive degradation and metabolic alterations observed in chronic wounds.

Comparison of intraocular treatment of DMTU and SOD following retinal ischemia in rats

The effect of intravitreal injections of DMTU (dimethylthiourea) and SOD (superoxide dismutase), two free radical scavengers, was evaluated in a rat model of retinal ischemia induced by elevated intraocular pressure. The drugs were administered just before or just after a 60 min ischemia. At days 2 and 7 after reperfusion, retinal recovery was evaluated by electroretinography. At day 7, layer thicknesses and cell rows were measured from histologic sections of paraffin-embedded retinas. In the vehicle-treated control group, we observed a decrease in the inner retinal layers and b-wave amplitude impairment. SOD injection (6 units/eye) protected the retina from ischemia/reperfusion injury. At day 2 after reperfusion, electroretinographic recovery was more efficient when SOD was administered just after ischemia (99%) than after pretreatment with SOD (81%) (p<0.03). In the DMTU-treated group (75 microg/eye), only the pretreatment induced significant electrophysiologic (40%) (p<0.001) and morphologic recovery.

Effects of hyaluronan on models of immediate and delayed hypersensitivity in the rat

Others have previously shown that superoxide dismutase conjugated with hyaluronan (HA) retains enzymic activity but is non-immunogenic. Whether HA could be widely used to prevent sensitisation to protein/polypeptide therapeutics is not known. In this study we investigated the effects of HA on bovine serum albumin (BSA) and methylated BSA pleural reactions in sensitised rats (active Arthus and delayed hypersensitivity reactions respectively) and on a reverse passive Arthus reaction in which rats received an intravenous injection of rabbit immunoglobulin and intrapleural challenge with goat anti rabbit immunoglobulin. HA suppressed the active Arthus and delayed hypersensitivity models when administered at the time of sensitisation but only the delayed hypersensitivity model at the time of intrapleural challenge. HA did not modulate the reverse passive Arthus reaction. The results show no evidence that simple mixing of HA with antigens masks antigenic determinants. However, HA appeared to have suppressive effects on both antibody and cell-mediated immune reactions. Therefore it may not be necessary to conjugate protein/polypeptide therapeutics to HA in order to prevent immune sensitisation.