The Influence of Polysaccharides/TiO2 on the Model Membranes of Dipalmitoylphosphatidylglycerol and Bacterial Lipids.

The aim of the study was to determine the bactericidal properties of popular medical, pharmaceutical, and cosmetic ingredients, namely chitosan (Ch), hyaluronic acid (HA), and titanium dioxide (TiO2). The characteristics presented in this paper are based on the Langmuir monolayer studies of the model biological membranes formed on subphases with these compounds or their mixtures. To prepare the Langmuir film, 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DPPG) phospholipid, which is the component of most bacterial membranes, as well as biological material-lipids isolated from bacteria Escherichia coli and Staphylococcus aureus were used. The analysis of the surface pressure-mean molecular area (π-A) isotherms, compression modulus as a function of surface pressure, CS-1 = f(π), relative surface pressure as a function of time, π/π0 = f(t), hysteresis loops, as well as structure visualized using a Brewster angle microscope (BAM) shows clearly that Ch, HA, and TiO2 have antibacterial properties. Ch and TiO2 mostly affect S. aureus monolayer structure during compression. They can enhance the permeability of biological membranes leading to the bacteria cell death. In turn, HA has a greater impact on the thickness of E. coli film.

Advances in Understanding the Mechanism of Ophthalmic Viscosurgical Device Retention in the Anterior Chamber or on the Corneal Surface during Ocular Surgery.

Retention durability, especially in the eye, is one of the most important properties of ophthalmic viscosurgical devices (OVDs) during ocular surgery. However, the information on the physical properties of OVDs is insufficient to explain their retention durability. The purpose of this study is to clarify the mechanism of OVD retention to improve understanding of the behavior of OVDs during ocular surgery. To elucidate the mechanism of OVD retention, we have developed a new test method for measuring repulsive force. As a result, the maximum repulsive force of OVDs was positively and well correlated with the retention durability of investigated OVDs. Consequently, we demonstrated that the repulsive force could be used as an index of retention durability on the ocular surface and in the eye. We directly compared the intraocular retention durability of three OVDs (Shellgan, Viscoat, and Opegan-Hi) in ex vivo porcine eyes. Opegan-Hi was immediately removed from the anterior chamber, but Shellgan and Viscoat remained largely in the anterior chamber as determined by fluorescence imaging. These results showed that the intraocular retention behavior of OVDs was similar to their ocular surface behavior in our previous report, suggesting that retention durability is dependent on the OVD itself. The retention durability of Shellgan seemed to be higher than that of Viscoat, and the maximum repulsive force of Shellgan was 1.35-fold higher than that of Viscoat. Therefore, the repulsive force might be a useful index for assessing the difference in the retention durability between OVDs such as Shellgan and Viscoat.

Upregulation of airway smooth muscle calcium-sensing receptor by low-molecular-weight hyaluronan.

We investigated the mechanisms involved in the development of airway hyperresponsiveness (AHR) following exposure of mice to halogens. Male mice (C57BL/6; 20-25 g) exposed to either bromine (Br2) or Cl2 (600 or 400 ppm, respectively, for 30 min) developed AHR 24 h after exposure. Nifedipine (5 mg/kg body wt; an L-type calcium channel blocker), administered subcutaneously after Br2 or Cl2 exposure, produced higher AHR compared with Br2 or Cl2 alone. In contrast, diltiazem (5 mg/kg body wt; a nondihydropyridine L-type calcium channel blocker) decreased AHR to control (air) values. Exposure of immortalized human airway smooth muscle cells (hASMC) to Br2 resulted in membrane potential depolarization (Vm Air: 62 ± 3 mV; 3 h post Br2:-45 ± 5 mV; means ± 1 SE; P < 0.001), increased intracellular [Ca2+]i, and increased expression of the calcium-sensing receptor (Ca-SR) protein. Treatment of hASMC with a siRNA against Ca-SR significantly inhibited the Br2 and nifedipine-induced Vm depolarization and [Ca2+]i increase. Intranasal administration of an antagonist to Ca-SR in mice postexposure to Br2 reversed the effects of Br2 and nifedipine on AHR. Incubation of hASMC with low-molecular-weight hyaluronan (LMW-HA), generated by exposing high-molecular-weight hyaluronan (HMW-HA) to Br2, caused Vm depolarization, [Ca2+]i increase, and Ca-SR expression to a similar extent as exposure to Br2 and Cl2. The addition of HMW-HA to cells or mice exposed to Br2, Cl2, or LMW-HA reversed these effects in vitro and improved AHR in vivo. We conclude that detrimental effects of halogen exposure on AHR are mediated via activation of the Ca-SR by LMW-HA.

Arabinogalactan and hyaluronic acid in ophthalmic solution: Experimental effect on xanthine oxidoreductase complex as key player in ocular inflammation (in vitro study).

Dry eye syndrome is a common disease associated to eyes inflammation, irritation and tear film instability. The enzymatic complex of xanthine oxidoreductase (XOR) is involved in the generation of reactive oxygen species (ROS) and uric acid that, in the end, can cause reperfusion injuries, irritation and pathological conditions. Furthermore, in the eye, it has been proposed that oxygen free radicals might play a significant role in retinal ischemic damage. A new artificial drop formulation based on arabinogalactan and hyaluronic acid has been proposed in this article. The uric acid and the ROS formation have been monitored. The effect of the arabinogalactan, the hyaluronic acid and their mixture has been studied. The arabinogalactan entails a uric acid and ROS reduction of 27% and 38% respectively; no significant reduction of uric acid or ROS has been observed after the addition of hyaluronic acid alone. Notably the combination of arabinogalactan and hyaluronic acid involves the reduction of uric acid and ROS equal to 38% and 62%, namely. This study demonstrates that this artificial drop formulation can markedly reduce the uric acid and ROS formation in vitro; thus, the use of this formulation may contribute in the resolution of the dry eye syndrome.

Practical Guidelines for Hyaluronic Acid Soft-Tissue Filler Use in Facial Rejuvenation.

BACKGROUND: Hyaluronic acid (HA) fillers are the most commonly used fillers for soft-tissue augmentation. The face is a dynamic structure. Facial rejuvenation by filler products depends on mechanical forces on the region of the face. The successful use of injectable HA fillers requires an understanding of the options available. OBJECTIVE: The purpose of this study is to measure the rheological properties of HA fillers and to clarify how to select these fillers considering their rheological properties. MATERIALS AND METHODS: Rheological characterization was performed on 41 fillers. Physical parameters directly linked to product performance were measured. RESULTS: The properties of the HA fillers varied. These findings provide a basis for selection guideline regarding rheological properties in facial rejuvenation. CONCLUSION: The authors' report is the largest study to determine the rheological properties of HA fillers to date. Understanding the fillers' properties can help physicians select the appropriate fillers for more predictable and sustainable results.

Is platelet-rich plasma effective for the treatment of knee osteoarthritis? A systematic review and meta-analysis of level 1 and 2 randomized controlled trials.

INTRODUCTION: The purpose of this study was to perform a systematic review and meta-analysis comparing intra-articular knee injection of PRP and hyaluronic acid and investigate clinical outcomes and pain at both 6 and 12 months. METHODS: A systematic review of Medline, Embase, Scopus, and Google Scholar was performed in the English and German literature reporting on intra-articular knee injections for knee osteoarthritis. All level 1 and 2 studies with a minimum of 6-month follow-up in patients with knee osteoarthritis from 2010 to 2019 were included. Clinical outcome was assessed by WOMAC and IKDC scores and pain by VAS and WOMAC pain scores. Subgroup analysis for autologous platelet-rich plasma (ACP) was performed. Publication bias and risk of bias were assessed using the Cochrane Collaboration's tools. The GRADE system was used to assess the quality of the body of evidence. Heterogeneity was assessed using χ2 and I2 statistics. RESULTS: Twelve studies (1,248 cases; 636 PRP, 612 HA) met the eligibility criteria. The pooled estimate demonstrated non-significant differences between PRP and HA for clinical outcomes at 6 months (p = 0.069) and at 12 months (p = 0.188). However, the pooled estimate for pain did demonstrate significant differences in favour of PRP at 6 months (p = 0.001) and 12 months (p = 0.001). For the ACP subgroup (249 cases), the pooled estimate for these studies demonstrated significant differences in favour of PRP (p < 0.0001) at 6 months. CONCLUSION: The results of this systematic review and meta-analysis suggest that PRP is superior to HA for symptomatic knee pain at 6 and 12 months. ACP appears to be clearly superior over HA for pain at both 6 and 12 months. There were no advantages of PRP over HA for clinical outcomes at both 6 and 12 months. LEVEL OF EVIDENCE: Level 2; systematic review and meta-analysis.

Specifically Sized Hyaluronan (35 kDa) Prevents Ethanol-Induced Disruption of Epithelial Tight Junctions Through a layilin-Dependent Mechanism in Caco-2 Cells.

BACKGROUND: Specific-sized species of the carbohydrate hyaluronan elicit a variety of cellular responses mediating tissue integrity and repair, as well as regulating inflammatory responses. Orally provided hyaluronan with an average molecular weight of 35 kDa (HA35) protects mice from short-term ethanol (EtOH)-induced liver injury. This protection was associated with maintenance of the colocalization of zonula occludens-1 (ZO-1) and occludin at tight junctions in the proximal colon. However, it is not known whether HA35 also protects other regions of the intestine or whether protection is due to a direct and/or indirect interaction of HA35 with the intestinal epithelium. METHODS: Female C57BL/6J mice were fed an EtOH containing diet or pair-fed control diet (4 days) and treated with or without HA35 via daily gavage during the last 3 days of EtOH feeding. Intestinal morphology and tight junction integrity were assessed. Differentiated Caco-2 cells were transfected or not with scrambled siRNA or siRNA targeting layilin, a hyaluronan receptor. Caco-2 cells were treated with or without HA35 prior to challenge with EtOH. Localization of tight junction proteins, fluorescein isothiocyanate (FITC)-dextran permeability, and transepithelial electrical resistance (TEER) were evaluated. RESULTS: While short-term EtOH did not result in any apparent changes in the gross morphology of the intestine, colocalization of ZO-1 and occludin at tight junctions was decreased in the proximal and distal colon. HA35 prevented these effects of EtOH. In differentiated Caco-2 cells, EtOH decreased the localization of ZO-1 and occludin at tight junctions and increased permeability of FITC-dextran. At higher concentrations, EtOH also decreased TEER. Pretreatment with HA35 prevented these changes. When the hyaluronan receptor layilin was knocked down in Caco-2 cells, HA35 no longer protected cells from EtOH-induced loss of tight junctions. CONCLUSIONS: Taken together, these data indicate that HA35 interacts with layilin on intestinal epithelial cells and maintains intestinal tight junction integrity during short-term EtOH exposure.

Instillation of hyaluronan reverses acid instillation injury to the mammalian blood gas barrier.

Acid (HCl) aspiration during anesthesia may lead to acute lung injury. There is no effective therapy. We hypothesized that HCl instilled intratracheally in C57BL/6 mice results in the formation of low-molecular weight hyaluronan (L-HA), which activates RhoA and Rho kinase (ROCK), causing airway hyperresponsiveness (AHR) and increased permeability. Furthermore, instillation of high-molecular weight hyaluronan (H-HA; Yabro) will reverse lung injury. We instilled HCl in C57BL/6 wild-type (WT), myeloperoxidase gene-deficient (MPO-/-) mice, and CD44 gene-deficient (CD44-/-) mice. WT mice were also instilled intranasally with H-HA (Yabro) at 1 and 23 h post-HCl. All measurements were performed at 1, 5, or 24 h post-HCl. Instillation of HCl in WT but not in CD44-/- resulted in increased inflammation, AHR, lung injury, and L-HA in the bronchoalveolar lavage fluid (BALF) 24 h post-HCl; L-HA levels and lung injury were significantly lower in HCl-instilled MPO-/- mice. Isolated perfused lungs of HCl instilled WT but not of CD44-/- mice had elevated values of the filtration coefficient ( Kf). Addition of L-HA on the apical surface of human primary bronchial epithelial cell monolayer decreased barrier resistance ( RT). H-HA significantly mitigated inflammation, AHR, and pulmonary vascular leakage at 24 h after HCl instillation and mitigated the increase of Kf and RT, as well as ROCK2 phosphorylation. Increased H- and L-HA levels were found in the BALF of mechanically ventilated patients but not in healthy volunteers. HCl instillation-induced lung injury is mediated by the L-HA-CD44-RhoA-ROCK2 signaling pathway, and H-HA is a potential novel therapeutic agent for acid aspiration-induced lung injury.

COMPARISON OF CORNEAL WETTING PROPERTIES OF DIFFERENT DISPERSIVE OPHTHALMIC VISCOSURGICAL DEVICES: An Optical Coherence Tomography Study.

PURPOSE: To compare corneal wetting performances of different dispersive ophthalmic viscosurgical devices. METHODS: Three different types of dispersive ophthalmic viscosurgical devices, hydroxypropyl methylcellulose %2 (HPMC), sodium hyaluronate %3-sodium chondroitin sulphate %4 (HACS), and sodium hyaluronate %3 (HA), were applied on corneal surfaces of 10 healthy volunteer subjects repeatedly at 3 different time points. Corneal wetting properties of the ophthalmic viscosurgical devices were compared qualitatively and quantitatively by anterior segment optical coherence tomography for 30 minutes. RESULTS: Sodium hyaluronate 3% and HACS applications had a higher mean precorneal ophthalmic viscosurgical device thickness than HPMC application at all time points (seventh minute HPMC: 105.2 ± 25.3 µm, HA: 561.4 ± 115.8 µm, HACS: 481.2 ± 55 µm, P < 0.001). All HPMC applications were terminated by the 12th minute because of insufficient corneal wetting. Mean survival estimate time was significantly shortest for HPMC (11.5 ± 0.5 minutes, P < 0.001) and longest for HA (29.7 ± 0.28 minutes). It was slightly shorter for HACS (26.9 ± 0.87 minutes, P = 0.007) than the HA application. CONCLUSION: Sodium hyaluronate 3% and HACS provide superior corneal covering compared with HPMC with an effect that can be maintained up to 30 minutes. They may be an effective option for corneal wetting during long vitreoretinal surgeries with longer duration of effect and fever number of applications.

Phacoemulsification with hydrodelineation and OVD-assisted hydrodissection in posterior polar cataract.

BACKGROUND: To evaluate the results and complications of phacoemulsification with hydrodelineation and ophthalmic viscosurgical device (OVD)-assisted hydrodissection for posterior polar cataract (PPC). METHODS: Medical records of 24 eyes from 17 patients with clinical diagnosis of PPC, who underwent phacoemulsification with hydrodelineation and OVD-assisted hydrodissection, were retrospectively reviewed. RESULTS: The incidence of posterior capsule rupture (PCR) was 16.67% (4/24): 2 cases occurred during epinucleus removal, and 2 cases occurred during OVD removal after the implantation of the intraocular lens into the bag. No nucleus piece or lens materials dropped into the vitreous during cataract surgery, and no obvious postoperative complications were found during follow-up. All patients had improved best-corrected visual acuity (BCVA) 1 month postoperatively. CONCLUSION: OVD-assisted hydrodissection could be an effective technique in phacoemulsification to reduce the incidence of PCR and achieve satisfactory postoperative outcomes.

Can hybrid hyaluronic acid represent a valid approach to treat rizoarthrosis? A retrospective comparative study.

BACKGROUND: Osteoarthritis (OA) of the trapeziometacarpal joint (TMJ) is a disabling condition with a significant impact on quality of life. The optimal management of hand OA requires a combination of non-pharmacological and pharmacological treatments that include intra-articular (i.a.) therapy. EULAR experts recommend corticosteroid injections in TMJ OA and underline the usefulness of hyaluronic acid (HA). The aim of this study was the assessment of the efficacy and tolerability of i.a. injections of a hybrid formulation of HA (Sinovial H-L®) in comparison to triamcinolone in patients with TMJ OA. METHODS: This 6-months observational comparative study, retrospective analyzed the medical records of 100 patients with monolateral or bilateral TMJ OA, treated with two injections of Sinovial H-L® (Sinovial H-L Group) or of triamcinolone acetonide (Triamcinolone Group). Clinical assessments were recorded at the time of the first and second injection and after one, 3 and 6 months. The primary outcomes were the change in global pain on a Visual Analogue Scale (VAS) and in hand function evaluated by the Functional Index for Hand OA (FIHOA) from baseline to month 6. Secondary outcomes were the improvement of the duration of morning stiffness, Health Assessment Questionnaire (HAQ) and the Medical Outcomes Study 36-Item Short Form (SF-36). The comparison between the two groups of treatment were performed with the Wilcoxon rank-sum test for continuous variables and with chi-square or Fisher exact test for categorical variables. Statistical significance was set at p < 0.05. RESULTS: Both therapies provided effective pain relief and joint function improvement, but the benefits achieved were statistically significantly superior in the Sinovial H-L Group than the Triamcinolone Group after one month (p < 0.01) from the beginning of the therapy and during the 6-months follow-up (p < 0.001). Furthermore, Sinovial H-L® was associated with a significant decrease in the duration of morning stiffness and with a significant improvement in the HAQ score and physical component summary (PCS)-SF-36. CONCLUSIONS: Our results suggested that the hybrid formulation of HA may be more effective than triamcinolone in pain relief and joint function improvement with a rapid and persistent effect, resulting a valid alternative to steroid in the management of TMJ OA. TRIAL REGISTRATION: ClinicalTrials.gov, date of registration: June 14, 2017, NCT03200886 . The present trial was retrospectively registered.

Anti-adhesive effect of solid mixture of sodium hyaluronate/carboxymethylcellulose in murine nasal cavities.

The purpose of the study was to evaluate the effect of a solid mixture of sodium hyaluronate and carboxymethylcellulose (S-HA/CMC) for the prevention of adhesions after iatrogenic mucosal injury in murine nasal cavities. We introduced iatrogenic adhesions into the bilateral nasal cavities of 20 male Sprague-Dawley rats. S-HA/CMC was applied to the left nasal cavity, while no packing was placed in the right nasal cavity as a control. At 1, 2, and 4 weeks post-procedure, we examined the number of adhesions, the ratio of the longest cross-sectional length of adhesion to septal cartilage length (RAC), and the degree of fibrosis. S-HA/CMC significantly reduced the number of adhesions when compared to the control group in total (p = 0.031), but not at each individual time point. The S-HA/CMC group showed significantly shorter RAC than the control group in total (p = 0.044), but not at each individual time point. The total fibrosis score was less severe in the S-HA/CMC group than in the control group (p < 0.001), with a significant difference between the two groups at the second week (p = 0.001). Therefore, in an animal model, S-HA/CMC can prevent post-injury mucosal adhesions suggesting a potential for clinical applications in endoscopic sinus surgery. Further clinical trials are needed to determine the safety and efficacy of S-HA/CMC as nasal packing after endoscopic sinus surgery.

[Chondroprotectors: A range of application in general somatic practice]. / Khondroprotektory: spektr primeneniia v obshchesomaticheskoi praktike.

Chondroprotectors (CP) are biological agents that contribute to the regeneration of the cartilage surfaces and articular capsule, participating in the metabolic processes of the articular cartilage. Progressive loss of hyaline cartilage and lower levels of chondroitin sulfate were observed in osteoarthritis (OA) at different sites, including dorsopathy. OA therapy is aimed at slowing disease progression, relieving pain symptoms, and reducing functional disorders. For this purpose, oral or injectable CPs (Chondroguard, Sustaguard) are prescribed. The optimal dosing regimen of parenteral CPs is the following: three intramuscular Chondrogard 1 ml (100 mg) jections during the first week; 25-30 intramuscular chondroguard 2 ml (200 mg) injections every other day during the second week, a repeat cycle after 6 months; Sustaguard 400 mg thrice weekly for 4 weeks.

A randomised, double-blinded, placebo-controlled clinical study on intra-articular hyaluronan treatment in equine lameness originating from the metacarpophalangeal joint.

BACKGROUND: Intra-articular inflammation resulting in lameness is a common health problem in horses. Exogenous intra-articular hyaluronic acid has been shown to provide an analgesic effect and reduce pain in equine and human osteoarthritis. High molecular weight non-animal stabilized hyaluronic acid (NASHA) has gained popularity in the treatment of human arthritic conditions due to its long-acting pain-relieving effects. The aim of this study was to compare the response to treatment of lameness localized in the equine metacarpophalangeal joint injected with non-animal stabilized hyaluronic acid (NASHA) and placebo (saline). Twenty-seven clinically lame horses with a positive response to diagnostic intra-articular anaesthesia of the metacarpophalangeal joint and with no, or at most mild, radiographic changes in this joint were included in the study. Horses in the treatment group (n = 14) received 3 mL of a NASHA product intra-articularly, and those in the placebo group (n = 13) received an equivalent volume of sterile 0.9% saline solution. RESULTS: The change in the lameness score did not significantly differ between NASHA and placebo groups (P = 0.94). Scores in the flexion test improved more in the NASHA group compared with placebo (P = 0.01). The changes in effusion and pain in flexion were similar (P = 0.94 and P = 0.27, respectively) when NASHA and placebo groups were compared. A telephone interview follow-up of the owners three months post-treatment revealed that 14 of the 21 horses (67%) were able to perform at their previous level of exercise. CONCLUSIONS: In the present study, a single IA NASHA injection was not better than a single saline injection for reducing lameness in horses with synovitis or mild osteoarthritis. However, the results of this study indicate that IA NASHA may have some beneficial effects in modifying mild clinical signs but more research is needed to evaluate whether the positive effect documented ie. reduced response in the flexion test is a true treatment effect.

The mechanism of action for hyaluronic acid treatment in the osteoarthritic knee: a systematic review.

BACKGROUND: Knee osteoarthritis (OA) is one of the leading causes of disability within the adult population. Current treatment options for OA of the knee include intra-articular (IA) hyaluronic acid (HA), a molecule found intrinsically within the knee joint that provides viscoelastic properties to the synovial fluid. A variety of mechanisms in which HA is thought to combat knee OA are reported in the current basic literature. METHODS: We conducted a comprehensive literature search to identify currently available primary non-clinical basic science articles focussing on the mechanism of action of IA-HA treatment. Included articles were assessed and categorized based on the mechanism of action described within them. The key findings and conclusions from each included article were obtained and analyzed in aggregate with studies of the same categorical assignment. RESULTS: Chondroprotection was the most frequent mechanism reported within the included articles, followed by proteoglycan and glycosaminoglycan synthesis, anti-inflammatory, mechanical, subchondral, and analgesic actions. HA-cluster of differentiation 44 (CD44) receptor binding was the most frequently reported biological cause of the mechanisms presented. High molecular weight HA was seen to be superior to lower molecular weight HA products. HA derived through a biological fermentation process is also described as having favorable safety outcomes over avian-derived HA products. CONCLUSIONS: The non-clinical basic science literature provides evidence for numerous mechanisms in which HA acts on joint structures and function. These actions provide support for the purported clinical benefit of IA-HA in OA of the knee. Future research should not only focus on the pain relief provided by IA-HA treatment, but the disease modification properties that this treatment modality possesses as well.

Optimal Viscosity and Particle Shape of Hyaluronic Acid Filler as a Scaffold for Human Fibroblasts.

The authors previously reported that cultured human fibroblasts suspended in a hyaluronic acid filler can produce human dermal matrices with extended in vivo stability in animal and clinical studies. The present study was undertaken to determine the optimal viscosity and particle shape of hyaluronic acid filler as a scaffold for cultured human dermal fibroblasts to enhance the maximal viability of injected cells. The fibroblasts were suspended in either 1 of 3 hyaluronic acid viscosities at 2 different particle shapes. The viscosities used in this study were low (600,000-800,000 centipoises), moderate (2,000,000-4,000,000 centipoises), and high (8,000,000-12,000,000 centipoises). The particle shape was evaluated by testing round and irregular shapes. The fibroblast mixed bioimplants were injected into the back of individual athymic nude mice. The levels of type I collagen were measured using fluorescent-activated cell sorting (FACS) and immunohistochemical staining at 16 weeks after the injections. Results of FACS demonstrated that the mean cell ratio with human collagens in the moderate viscosity group was greater than those of control, low, and high viscosity groups. An immunohistochemical study showed similar results. The moderate viscosity group demonstrated the highest positive staining of human collagens. However, there were no significant differences between groups of irregular and round shape particles. A hyaluronic acid bioimplant with moderate viscosity is superior to that with low or high viscosity in the viability for human fibroblasts. However, the particle shape does not influence the viability of the fibroblasts.

Microvascular permeability to water is independent of shear stress, but dependent on flow direction.

Endothelial cells in a cultured monolayer change from a "cobblestone" configuration when grown under static conditions to a more elongated shape, aligned with the direction of flow, after exposure to sustained uniform shear stress. Sustained blood flow acts to protect regions of large arteries from injury. We tested the hypothesis that the stable permeability state of individually perfused microvessels is also characteristic of flow conditioning. In individually perfused rat mesenteric venular microvessels, microvascular permeability, measured as hydraulic conductivity (Lp), was stable [mean 1.0 × 10(-7) cm/(s × cmH2O)] and independent of shear stress (3-14 dyn/cm(2)) for up to 3 h. Vessels perfused opposite to the direction of normal blood flow exhibited a delayed Lp increase [ΔLp was 7.6 × 10(-7) cm/(s × cmH2O)], but the increase was independent of wall shear stress. Addition of chondroitin sulfate and hyaluronic acid to perfusates increased the shear stress range, but did not modify the asymmetry in response to flow direction. Increased Lp in reverse-perfused vessels was associated with numerous discontinuities of VE-cadherin and occludin, while both proteins were continuous around the periphery of forward-perfused vessels. The results are not consistent with a general mechanism for graded shear-dependent permeability increase, but they are consistent with the idea that a stable Lp under normal flow contributes to prevention of edema formation and also enables physiological regulation of shear-dependent small solute permeabilities (e.g., glucose). The responses during reverse flow are consistent with reports that disturbed flows result in a less stable endothelial barrier in venular microvessels.

Mechanisms involved in enhancement of the expression and function of aggrecanases by hyaluronan oligosaccharides.

OBJECTIVE: Small hyaluronan (HA) oligosaccharides serve as competitive receptor antagonists to displace HA from the cell surface and induce cell signaling events. In articular chondrocytes, this cell signaling is mediated by the HA receptor CD44 and induces stimulation of genes involved in matrix degradation, such as matrix metalloproteinases (MMPs) as well as matrix repair genes including type II collagen, aggrecan, and HA synthase 2. The objective of this study was to determine changes in the expression and function of aggrecanases after disruption of chondrocyte CD44-HA interactions. METHODS: Bovine articular chondrocytes or bovine cartilage tissue was pretreated with a variety of inhibitors of major signaling pathways prior to the addition of HA oligosaccharides. Changes in aggrecanase were monitored by real-time reverse transcription-polymerase chain reaction and Western blot analyses of ADAMTS-4, ADAMTS-5, and aggrecan proteolytic fragments. To test the interactions between ADAMTS-4 and membrane type 4 MMP (MT4-MMP), protein lysates purified from stimulated chondrocytes were subjected to coimmunoprecipitation. RESULTS: Disruption of chondrocyte CD44-HA interactions with HA oligosaccharides induced the transcription of ADAMTS-4 and ADAMTS-5 in a time- and dose-dependent manner. The association of glycosyl phosphatidylinositol-anchored MT4-MMP with ADAMTS-4 was also induced in articular chondrocytes by HA oligosaccharides. Inhibition of the NF-κB pathway blocked HA oligosaccharide-mediated stimulation of aggrecanases. CONCLUSION: Disruptive changes in chondrocyte-matrix interactions by HA oligosaccharides induce matrix degradation and elevate aggrecanases via the activation of the NF-κB signaling pathway.

The effect of hyaluronan combined with microfracture on the treatment of chondral defects: an experimental study in a rabbit model.

Because articular hyaline cartilage has low potential for regeneration, numerous methods and techniques have been proposed to induce the reparation process. Microfracture is a convenient procedure for this purpose. However, the quality of the new cartilage after microfracture is still not as proper as original. In this experimental study, we used microfracture in combination with intraarticular application of hyaluronan in rabbit knee articular defect. Bilateral knee arthrotomies, chondral defects, and microfracture were created on each intercondylar notch in thirty rabbits. Rabbits received intraarticular injections of hyaluronan once a week for 3 weeks in the right knee, started from 1 week after injury. The left knees, which served as controls, were injected with normal saline. Biopsy was taken from both knees at the 4th and 6th weeks. In comparison with the control group, after 6 weeks we observed a higher potential for healing in the experimental group, with thicker and more organized repair tissue filling the defect. The current study reveals that application of hyaluronan after the microfracture might be beneficial in inducing articular cartilage defect reparation.

Activation of p38 mitogen-activated protein kinase is inhibited by hyaluronan via intercellular adhesion molecule-1 in articular chondrocytes stimulated with type II collagen peptide.

This study examined the activation of p38 mitogen-activated protein kinase with matrix metalloproteinase-13 (MMP-13) production by a synthetic peptide derived from type II collagen (CB12-II) and its inhibition by high molecular weight hyaluronan (HA) in chondrocytes. When cartilage explants or isolated chondrocytes in monolayer were incubated with CB12-II, the peptide (50 µM, 72 h) activated p38 in association with enhanced MMP-13 production. Inhibition studies with SB203580 (0.1 - 1 µM) indicated the requirement of p38 for CB12-II-induced MMP-13 production. Pretreatment with 2700 kDa HA (1 mg/ml, 1 h) resulted in significant suppression of CB12-II-stimulated MMP-13 production in cartilage as well as in chondrocyte monolayer cultures. HA (1 mg/ml) suppressed p38 activation by CB12-II, leading to a decrease in MMP-13 production. The antibody (20 µg/ml) to intercellular adhesion molecule-1 (ICAM-1), which has been recognized as a receptor of HA on chondrocytes, reversed the HA effect on CB12-II action. Thus, the present study clearly demonstrated that high molecular weight HA suppressed CB12-II-activated p38 via ICAM-1 in articular chondrocytes. HA could down-regulate the catabolic action of type II collagen fragments in osteoarthritic joints through the mechanism demonstrated in this study.