Resolving Atomic-Level Dynamics and Interactions of High-Molecular-Weight Hyaluronic Acid by Multidimensional Solid-State NMR.

High-molecular-weight (HMW) hyaluronic acid (HA) is a highly abundant natural polysaccharide and a fundamental component of the extracellular matrix (ECM). Its size and concentration regulate tissues' macro- and microenvironments, and its upregulation is a hallmark feature of certain tumors. Yet, the conformational dynamics of HMW-HA and how it engages with the components of the ECM microenvironment remain poorly understood at the molecular level. Probing the molecular structure and dynamics of HMW polysaccharides in a hydrated, physiological-like environment is crucial and also technically challenging. Here, we deploy advanced magic-angle spinning (MAS) solid-state NMR spectroscopy in combination with isotopic enrichment to enable an in-depth study of HMW-HA to address this challenge. This approach resolves multiple coexisting HA conformations and dynamics as a function of environmental conditions. By combining 13C-labeled HA with unlabeled ECM components, we detect by MAS NMR HA-specific changes in global and local conformational dynamics as a consequence of hydration and ECM interactions. These measurements reveal atom-specific variations in the dynamics and structure of the N-acetylglucosamine moiety of HA. We discuss possible implications for interactions that stabilize the structure of HMW-HA and facilitate its recognition by HA-binding proteins. The described methods apply similarly to the studies of the molecular structure and dynamics of HA in tumor contexts and in other biological tissues as well as HMW-HA hydrogels and nanoparticles used for biomedical and/or pharmaceutical applications.

Effectiveness of topical hyaluronic acid of different molecular weights in xerosis cutis treatment in elderly: a double-blind, randomized controlled trial.

Dry skin is a common dermatological condition that frequently affects the elderly. A contributing cause to dry skin is a reduced concentration of hyaluronic acid (HA) in both the epidermis and dermis. The effectiveness of moisturizer containing HA as a therapy for dry skin is impacted by its specific molecular weight. Low molecular weight HA (LMWHA) is believed to be more effective in replenishing skin hydration in aging skin compared to High Molecular Weight HA (HMWHA) due to its ability to penetrate the stratum corneum. However, there is a lack of clinical research supporting this claim. A double-blind, randomized controlled trial was conducted on 36 residents of a nursing home in Jakarta. The participants, aged between 60 and 80 years, had been diagnosed with dry skin. Each test subject was administered three distinct, randomized moisturizing lotions (LMWHA, HMWHA, or vehicle), to be topically applied to three separate sites on the leg. Skin capacitance (SCap), transepidermal water loss (TEWL), and specified symptom sum score (SRRC) were measured at weeks 0, 2, and 4. After four weeks of therapy, area that was treated with LMWHA showed greater SCap values compared to the area treated with HMWHA (56.37 AU vs. 52.37 AU, p = 0.004) and vehicle (56.37 AU vs. 49.01 AU, p < 0.001). All groups did not show any significant differences in TEWL and SRRC scores. No side effects were found in all groups. The application of a moisturizer containing LMWHA to the dry skin of elderly resulted in significant improvements in skin hydration compared to moisturizers containing HMWHA and vehicle. Furthermore, these moisturizers demonstrated similar safety in treating dry skin in the elderly. ClinicalTrials.gov Identifier NCT06178367, https://clinicaltrials.gov/study/NCT06178367 .

High molecular weight hyaluronic acid-liposome delivery system for efficient transdermal treatment of acute and chronic skin photodamage.

Photodamage is one of the most common causes of skin injury. High molecular weight hyaluronic acid (HHA) has shown immense potential in the treatment of skin photodamage by virtue of its anti-inflammatory, reparative, and antioxidative properties. However, due to its large molecular structure of HHA, HHA solution could only form a protective film on the skin surface in conventional application, failing to effectively penetrate the skin, which necessitates the development of new delivery strategies. Liposomes, with a structure similar to biological membranes, have garnered extensive attention as transdermal drug delivery carriers because of their advantages in permeability, dermal compatibility, and biosafety. Herein, we have developed a HHA-liposome transdermal system (HHL) by embedding HHA into the liposome structure using reverse evaporation, high-speed homogenization, and micro-jet techniques. The effective penetration and long-term residence of HHA in skin tissue were multidimensionally verified, and the kinetics of HHA in the skin were extensively studied. Moreover, it was demonstrated that HHL significantly strengthened the activity of human keratinocytes and effectively inhibits photo-induced cellular aging in vitro. Furthermore, a murine model of acute skin injury induced by laser ablation was established, where the transdermal system showed significant anti-inflammatory and immunosuppressive properties, promoting skin proliferation and scar repair, thereby demonstrating immense potential in accelerating skin wound healing. Meanwhile, HHL significantly ameliorated skin barrier dysfunction caused by simulated sunlight exposure, inhibited skin erythema, inflammatory responses, and oxidative stress, and promoted collagen expression in a chronic photodamage skin model. Therefore, this transdermal delivery system with biocompatibility represents a promising new strategy for the non-invasive application of HHA in skin photodamage, revealing the significant potential for clinical translation and broad application prospects. STATEMENT OF SIGNIFICANCE: The transdermal system utilizing hyaluronic acid-based liposomes enhances skin permeability and retains high molecular weight hyaluronic acid (HHL). In vitro experiments with human keratinocytes demonstrate significant skin repair effects of HHL and its effective inhibition of cellular aging. In an acute photodamage model, HHL exhibits stronger anti-inflammatory and immunosuppressive properties, promoting skin proliferation and scar repair. In a chronic photodamage model, HHL significantly improves skin barrier dysfunction, reduces oxidative stress induced by simulated sunlight, and enhances collagen expression.

Highly Concentrated Stabilized Hybrid Complexes of Hyaluronic Acid: Rheological and Biological Assessment of Compatibility with Adipose Tissue and Derived Stromal Cells towards Regenerative Medicine.

Cells and extracts derived from adipose tissue are gaining increasing attention not only in plastic surgery and for aesthetic purposes but also in regenerative medicine. The ability of hyaluronan (HA) to support human adipose stromal cell (hASC) viability and differentiation has been investigated. However, the compatibility of adipose tissue with HA-based formulation in terms of biophysical and rheological properties has not been fully addressed, although it is a key feature for tissue integration and in vivo performance. In this study, the biophysical and biochemical properties of highly concentrated (45 mg/mL) high/low-molecular-weight HA hybrid cooperative complex were assessed with a further focus on the potential application in adipose tissue augmentation/regeneration. Specifically, HA hybrid complex rheological behavior was observed in combination with different adipose tissue ratios, and hyaluronidase-catalyzed degradation was compared to that of a high-molecular-weight HA (HHA). Moreover, the HA hybrid complex's ability to induce in vitro hASCs differentiation towards adipose phenotype was evaluated in comparison to HHA, performing Oil Red O staining and analyzing gene/protein expression of PPAR-γ, adiponectin, and leptin. Both treatments supported hASCs differentiation, with the HA hybrid complex showing better results. These outcomes may open new frontiers in regenerative medicine, supporting the injection of highly concentrated hybrid formulations in fat compartments, eventually enhancing residing staminal cell differentiation and improving cell/growth factor persistence towards tissue regeneration districts.

Clinical and radiological efficacy of single-dose intra-articular high-molecular-weight hyaluronic acid in knee osteoarthritis.

Context: While visco-supplementation is being used for the treatment of knee osteoarthritis (OA), the published reports vary widely in benefits afforded by this treatment. It was therefore proposed to assess the objective parameters along with subjective outcomes. Aims: Our study assessed the radiological and clinical efficacy of single-dose high-molecular-weight intra-articular hyaluronic acid (HMW-IAHA) injection in knee OA. Settings and Design: This interventional cohort study was conducted in a calculated sample size of 44 patients with knee OA. Materials and Methods: Visual analog scale (VAS) and knee OA and outcome score (KOOS) were used for clinical assessment, and whole organ magnetic resonance imaging score (WORMS) for radiological assessment. The subjects were given a single dose of HMW-IAHA injection, 90 mg/3 ml, and were assessed on day 0 and day 90. Statistical Analysis: Statistical Package for Social Sciences (SPSS) software was used. Results: At the day 90 follow-up, there was an improvement in mean ± standard deviation values of VAS score (day 0: 8.53 ± 0.81, day 90: 5.97 ± 0.87), KOOS score (day 0: 27.33 ± 15.18, day 90: 57.26 ± 14.26), and the cartilage signal and morphology in the medial femorotibial joint (day 0: 11.02 ± 6.26 and day 90: 10.91 ± 6.22) and patellofemoral joint (day 0: 10.35 ± 4.36 and day 90: 10.28 ± 4.39) compartments. There was a decrease in synovitis score from 2.3 ± 1.61 to 1.3 ± 1.3 in the medial femorotibial joint compartment and total WORMS score (day 0: 66.57 ± 36.06, day 90: 65.14 ± 35.62). Conclusions: A single dose of intra-articular injection with high-molecular-weight hyaluronic acid produces improvement in the clinical symptoms and quality of life as well as is effective in maintaining the articular cartilage integrity and reducing synovial inflammation.

Prospective bacterial and fungal sources of hyaluronic acid: A review.

The unique biological and rheological properties make hyaluronic acid a sought-after material for medicine and cosmetology. Due to very high purity requirements for hyaluronic acid in medical applications, the profitability of streptococcal fermentation is reduced. Production of hyaluronic acid by recombinant systems is considered a promising alternative. Variations in combinations of expressed genes and fermentation conditions alter the yield and molecular weight of produced hyaluronic acid. This review is devoted to the current state of hyaluronic acid production by recombinant bacterial and fungal organisms.

Functional and Kinetic Treatment With Rehabilitation Combined With Cryotherapy Compared to Cryotherapy Alone in the Treatment of Acute Grade I or II Inversion Ankle Sprains: A Randomized Clinical Trial.

Objective: The purpose of this study was to compare Functional and Kinetic Treatment with Rehabilitation (FAKTR) combined with cryotherapy to cryotherapy alone in the treatment of acute grade I or II inversion ankle sprains. Methods: This prospective, randomized clinical trial of adult (18-40 years of age) participants (n = 40) with acute grade I or II inversion ankle sprain of less than 3 weeks, who were randomly allocated into a FAKTR and cryotherapy group (n = 20) or a cryotherapy only group (n = 20). The participants had 3 treatments (inclusive of the initial consultation), with a fourth as a measurement follow-up (2 weeks after the third treatment). Measurement procedures were completed at the outset of the first to third consultations and the fourth measurement only consultation. Clinical measures taken by a blinded research assistant included the Numerical Pain Rating Scale, Foot function index, algometer, digital inclinometer for ankle dorsiflexion range of motion measures, the figure-of-8 maneuver measured swelling, and the Stork-Balance-Stand Test. Results: Significant intergroup differences were observed for pain rating (P ≤ .01; 95% confidence interval [CI] -4.74 to 0.86), pain pressure threshold (P ≤ .05; 95% CI -1.06 to 1.52), balance and proprioception (P ≤ .01; 95% CI -5.28 to -1.39), and foot function index (P ≤ .01; 95% CI -30.12 to 4.83). No significant intergroup differences were observed in ankle dorsiflexion range of motion (P = .242; 95% CI -3.17 to 1.20) and edema measurements (P = .602; 95% CI 0.41-1.46). Conclusion: The FAKTR instrument assisted soft tissue mobilization treatment combined with cryotherapy indicated a trend toward greater clinical effectiveness than cryotherapy for measures of pain, pain pressure threshold, balance and proprioception, and foot function index; however, these outcomes were not reflected for ankle dorsiflexion range of motion and edema measurements.

The effect of chitosan/TiO2/hyaluronic acid subphase on the behaviour of 1,2-dioleoyl-sn-glycero-3-phosphocholine membrane.

The main aim of the study was to determine the effect of two polysaccharides: chitosan (Ch) and hyaluronic acid (HA), and/or titanium dioxide (TiO2) on the structure and behaviour of the 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) membrane. To achieve this goal the surface pressure as a function of the area per molecule (π-A) isotherm for the phospholipid monolayer was recorded. The shape of the π-A isotherms and compression-decompression cycles, as well as the compression modulus values, were analysed in terms of biocompatibility. Besides, morphology and thickness of the phospholipid layers obtained by means of Brewster angle microscope at different π, were determined. The obtained results show that both polysaccharides Ch, HA, as well inorganic TiO2 affect slightly the structure of the DOPC monolayer but do not disrupt it. Their presence brings no typical arrangements of both the polar heads and tails of DOPC molecules at the interface.

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

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

Clinical Outcomes Of Intra-Articular High Molecular Weight Hyaluronic Acid Injection For Hip Osteoarthritis- A Systematic Review And Meta-Analysis.

BACKGROUND: Osteoarthritis is the most common degenerative disease of the synovial joints in the elderly population with hip osteoarthritis as the second most commonly affected joint. A multitude of conservative treatments is used for pain relief and functional improvement including acetaminophen, NSAID, intra-articular corticosteroid, and viscosupplementation (VS). Different preparations of VS based on different molecular weights are commercially available. No systematic review or meta-analysis regarding the use of intra-articular high molecular weight hyaluronic acid (HMWHA) injection for the hip joint was published before. This review analyzes the efficacy of intra-articular HMWHA for hip osteoarthritis. METHODS: PubMed, Google Scholar, Cochrane Library for randomized trials describing the efficacy of HMWHA for hip osteoarthritis was searched. The search terms were osteoarthritis, hip joint, outcomes, viscosupplementation, and high molecular weight hyaluronic acid in different combinations. Standardized mean difference (SMD) in VAS for pain relief and Lequesne index for functional outcomes while risk ratio (RR) for complications was used for data pooling. RESULTS: Four studies comprising 185 and 189 patients in HMWHA and control groups were included, respectively. SMD for VAS and Lequesne index was -0.056 and -0.114, respectively while RR for complication was 0.879. CONCLUSIONS: Intra-articular HMWHA injection provided pain relief, functional improvement, and no severe complications on immediate short term basis. However, the results do not favor treatment with HMWHA over other treatment methods. Randomized trials are further necessary to provide data regarding comparisons between HMWHA for hip osteoarthritis concerning clinicians' convenience, compliance, duration of relief, and cost-effectiveness.

Downregulation of Hyaluronic acid-CD44 signaling pathway in cervical cancer cell by natural polyphenols Plumbagin, Pongapin and Karanjin.

Hyaluronic acid (HA)-CD44 pathway showed association with several malignancies. The natural polyphenols Plumbagin, Pongapin and Karanjin showed anti-cancer activities in different tumors including cervical carcinoma. To understand their mechanism of anti-cancer activity, the effect of the compounds on HA-CD44 pathway was analyzed in cervical cancer cell line HeLa. The mRNA expression of three different isoforms of CD44 i.e., CD44s, CD44v3, and CD44v6, was differentially downregulated by the compounds. This was validated by Western blot and immunocytochemical analysis of CD44s.The low molecular weight HA (LMW-HA) showed growth promoting activity in HeLa at low concentration, whereas high molecular weight HA (HMW-HA) had no such effect. The compounds could preferentially downregulate the LMW-HA level in HeLa, as evident in the cell as well as in the cell-free conditioned medium. Concentration-dependent upregulation of HA synthase-2 (HAS2) was seen in the cell by the compounds, whereas differential downregulation of hyalurinidases 1-4 (HYAL 1-4), predominantly HYAL1, were seen. The compounds could also downregulate the downstream target of the pathway p-AKT (T-308) in concentration-dependent manner. Thus, the compounds could attenuate the HA-CD44 pathway in HeLa cell to restrict the tumor growth.

Absorption, distribution, metabolism and excretion of hyaluronic acid during pregnancy: a matter of molecular weight.

INTRODUCTION: For many years hyaluronic acid (HA) was mainly used for its hydrating properties. However, new applications have recently arisen, considering the biological properties of HA and its molecular weight. Clinical application of low molecular weight HA (LMW-HA) initially was supported by specific absorption data. The identification of high molecular weight HA (HMW-HA) absorption pathways and the knowledge of its physiological role allowed to evaluate its clinical application. Based on the immunomodulatory properties of HMW-HA and its physiological involvement as signaling molecule, pregnancy represents an interesting context of application. AREA COVERED: This expert opinion includes in-vitro, in-vivo, ex-vivo and clinical studies on gestational models. It provides an overview of the physiological and the therapeutic role of HMW-HA in pregnancy starting from its metabolism. Indeed, HMW-HA is widely involved in several physiological processes as implantation, immune response, uterine quiescence and cervical remodeling, and therefore is an essential molecule for a successful pregnancy. EXPERT OPINION: Available evidence suggests that HMW-HA administration can support physiological pregnancy, favoring blastocyst adhesion and development, preventing miscarriage and pre-term birth. For this reason, supplementation in pregnancy should be evaluated.

The Effects of High Molecular Weight Hyaluronic Acid Eye Drop Application in Environmental Dry Eye Stress Model Mice.

Hyaluronic acid (HA) ophthalmic solution is widely used in dry eye treatment worldwide. However, there are no reports comparing the dry eye treatment effects of high molecular weight HA with low molecular weight HA. Sixty eight-week-old C57BL/6 mice were assigned to the following 6 groups and exposed to environmental dry eye stress (EDES) that mimics office work environment: 1) 0.1% low molecular weight HA (LMWHA) eye drops, 2) 0.3% LMWHA eye drops, 3) 3% diquafosol sodium (DQ) eye drops, 4) 0.15% high molecular weight HA (HMWHA) eye drops, 5) no treatment with exposure to EDES (EDES+/Treatment-), and 6) no treatment without exposure to EDES (EDES-/Treatment-). After EDES, the HMWHA group had significantly longer break-up time (BUT) than the 0.1%, 0.3% LMWHA groups and the DQ group. After EDES, the HMWHA group had significantly lower lissamine green staining scores than the LMWHA and DQ groups. Subepithelial presumed dendritic cell density in the HMWHA group was significantly lower than the EDES+/Treatment- group. After EDES exposure, Conjunctival Muc5AC mRNA expression in the HMWHA group was significantly higher than the 0.1 and 0.3% LMWHA groups. Ophthalmic HMWHA solution may have a better dry eye treatment effect than LMWHA or DQ solution, owing to its anti-inflammatory effect.

Comparison of two different molecular weight intra-articular injections of hyaluronic acid for the treatment of knee osteoarthritis.

BACKGROUND: Knee osteoarthritis (OA) is an incurable joint disorder, representing a major public health issue. Among options for symptom control, viscosupplementation with hyaluronic acid (HA) had established usefulness in pain and function improvement of the knee. However, it is not clear which form of HA yields better results. MATERIAL AND METHODS: We compared two HA preparations with high (HMW) or low molecular weight (LMW) in terms of pain control and function improvement using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the visual analog scale (VAS) score in patients with knee OA. During 2013, 80 patients were enrolled in this prospective, double-blind, randomized study. Each patient received a weekly injection of either preparation with a total of five injections for the LMW group and three for the HMW group. They were evaluated at baseline, five weeks, three months and one year after treatment. RESULTS: In both groups, HA treatment resulted in significant improvement in pain and function that begun immediately after treatment and lasted for one year. However when compared with each other, HMW and LMW groups were comparable in mean WOMAC, and VAS score at each time point. Neither preparation can interrupt disease progression as radiological findings remained constant during follow-up. CONCLUSIONS: Intra-articular injections using HMW or LMW HA can improve stiffness, joint function and pain in patients suffering from knee OA. However, no clear benefit seems to exist between the two preparations and neither can slow disease progression. Hippokratia 2016, 20(1): 26-31.

Pain relief and improved physical function in knee osteoarthritis patients receiving ongoing hylan G-F 20, a high-molecular-weight hyaluronan, versus other treatment options: data from a large real-world longitudinal cohort in Canada.

From the Southwestern Ontario database, one of the largest primary-care datasets in Canada, 1,263 patients with osteoarthritis (OA) of one or both knees were identified who received two consecutive series of intra-articular (IA) injections of hylan G-F 20 preparation and no other prescribed OA medications, and were evaluated fully between 2006 and 2012. A cohort of 3,318 demographically matched OA patients who had not been treated with IA injection therapy was identified from the same database for comparison. Responses to therapy were assessed by means of a 10-point visual analog scale (VAS) for pain at rest and after completion of a 6-minute walk test (6 MWT), while physical capacity was measured by performance in the 6 MWT itself. After two cycles of hylan G-F 20 therapy, the average VAS score for pain at rest declined from 7.82 ± 1.27 at baseline to 4.16 ± 1.51 (average change 3.66 ± 1.78, significantly more than the reduction of 3.12 ± 2.03 seen in the reference group [P < 0.012]) and the average VAS score for pain after the 6 MWT decreased by 5.56 ± 1.74 points (from 9.58 ± 0.4 at baseline to 4.02 ± 1.67 at the final assessment), a significantly larger change than that seen in the reference group (Δ2.99 ± 1.85; P<0.001 for intergroup comparison). Distance walked in the 6 MWT increased on average by 115 m, significantly more than that seen in the reference group (Δ91 m; P < 0.001 for intergroup comparison). These findings from a primary-care database suggest sustained benefits in terms of pain and physical function from repeat cycles of IA injections of hylan G-F 20 and no other prescribed OA medications in adults with OA of the knee.

Effects of cross-linked high-molecular-weight hyaluronic acid on epidural fibrosis: experimental study.

OBJECT: Epidural fibrosis is nonphysiological scar formation, usually at the site of neurosurgical access into the spinal canal, in the intimate vicinity of and around the origin of the radicular sheath. The formation of dense fibrous tissue causes lumbar and radicular pain. In addition to radicular symptoms, the formation of scar tissue may cause problems during reoperation. The authors aimed to investigate the effects of cross-linked high-molecular-weight hyaluronic acid (HA), an HA derivative known as HA gel, on the prevention of epidural fibrosis by using histopathological and biochemical parameters. METHODS: Fifty-six adult female Sprague-Dawley rats were evaluated. The rats were divided into 4 groups. Rats in the sham group (n = 14) underwent laminectomy and discectomy and received no treatment; rats in the control group (n = 14) underwent laminectomy and discectomy and received 0.9% NaCl treatment in the surgical area; rats in the HA group (n = 14) received HA treatment at the surgical area after laminectomy and discectomy; and rats in the HA gel group (n = 14) underwent laminectomy and discectomy in addition to receiving treatment with cross-linked high-molecular-weight HA in the surgical area. All rats were decapitated after 4 weeks, and the specimens were evaluated histopathologically and biochemically. The results were statistically compared using the Mann-Whitney U-test. RESULTS: Compared with the sham and control groups, the HA and HA gel groups showed significantly lower fibroblast cell density and tissue hydroxyproline concentrations (p < 0.05). There was statistically significant lower dural adhesion and foreign-body reaction between the control and HA gel groups (p < 0.05). Granulation tissue and epidural fibrosis were significantly lower in the HA and HA gel groups compared with the sham group (p < 0.05). There were no significant differences in any histopathological parameters or biochemical values between Groups 3 and 4 (p > 0.05). CONCLUSIONS: Cross-linked high-molecular-weight HA had positive effects on the prevention of epidural fibrosis and the reduction of fibrotic tissue density. The efficacy of this agent should also be verified in further experimental and clinical studies.

High molecular weight hyaluronic acid increases the differentiation potential of the murine chondrocytic ATDC5 cell line.

Osteoarthritis (OA) is a group of common, chronic, and painful inflammatory joint diseases. One important finding in OA patients is a remarkable decrease in the molecular weight of hyaluronic acid (HA) in the synovial fluid of affected joints. Therapeutic HA is available to patients in most parts of the world as a viscosupplementation product for the treatment of OA. Previous clinical reports show that high molecular weight HA (HMWHA) more effectively relieves pain than low molecular weight HA (LMWHA). However, the mechanism behind this finding remains unclear. In this study, we investigated whether a LMWHA (Low-0.9 MDa) and two types of HMWHA (High-1.9 MDa and 6 MDa) differentially affected chondroregulatory action. We tested this using ATDC5 cell, a murine chondrocytic cell line widely used in culture systems to study chondrogenic differentiation. We found that HMWHA, especially hylan G-F 20 (High-6 MDa), significantly induced aggrecan and proteoglycan accumulation, nodule formation, and mRNA expression of chondrogenic differentiation markers in a time- and dose-dependent manner. In addition, we showed that HMWHA prevented TNF-α induced inhibition of chondrogenic differentiation, with no effect on cell proliferation or viability. These results reveal that HMWHA significantly promotes chondrogenic differentiation of ATDC5 cells in vitro, and suggest that HMWHA plays a significant chondroregulatory role in vivo.

[Treatment of acute full-thickness chondral defects with high molecular weight hyaluronic acid; an experimental model]. / Tratamiento de lesiones condrales agudas de espesor completo con ácido hialurónico de alto peso molecular; un modelo experimental.

PURPOSE: To evaluate the effect of 2 different protocols of intra-articular hyaluronic acid (HA, hylan G-F20) to articular cartilage regeneration in acute full-thickness chondral defects. MATERIALS AND METHODS: Full-thickness chondral defects of 3 x 6 mm were performed into the lateral femoral condyles of New Zealand rabbits, treated with a single or three doses of HA. The animals were sacrified at 12 weeks and the regenerated tissue was evaluated by direct observation and histology with the ICRS scale. Macroscopically, in both groups treated with HA the defects were filled with irregular tissue with areas similar to hyaline cartilage and others in which depressed areas with exposed subchondral bone were observed. Histological analysis showed in both groups treated with HA a hyaline-like cartilage compared to control group. However, the score of the International Cartilage Repair Society (ICRS) scale did not show differences between the groups treated with HA. CONCLUSION: The use of single dose or 3 doses of AH in acute chondral lesions has a limited and similar benefit in articular cartilage regeneration.