High molecular weight hyaluronic acid regulates P. gingivalis–induced inflammation and migration in human gingival fibroblasts via MAPK and NF-κB signaling pathway

Synergistic Effects of Shed-Derived Exosomes, Cu2+, and an Injectable Hyaluronic Acid Hydrogel on Antibacterial, Anti-inflammatory, and Osteogenic Activity for Periodontal Bone Regeneration

The primary pathology of periodontitis involves the gradual deterioration of periodontal tissues resulting from the inflammatory reaction triggered by bacterial infection. In this study, a novel drug for periodontal pocket injection, known as the Shed-Cu-HA hydrogel, was developed by incorporating copper ions (Cu2+) and Shed-derived exosomes (Shed-exo) inside the hyaluronic acid (HA) hydrogel. Suitable concentrations of Cu2+ and Shed-exo released from Shed-Cu-HA enhanced cell viability and cell proliferation of human periodontal ligament stem cells. Additionally, the Shed-Cu-HA demonstrated remarkable antibacterial effects against the key periodontal pathogen (Aa) owing to the synergistic effect of Cu2+ and HA. Furthermore, the material effectively suppressed macrophage inflammatory response via the IL-6/JAK2/STAT3 pathway. Moreover, the Shed-Cu-HA, combining the inflammation-regulating properties of HA with the synergistic osteogenic activity of Shed-exo and Cu2+, effectively upregulated the expression of genes and proteins associated with osteogenic differentiation. The experimental findings from a mouse periodontitis model demonstrated that the administration of Shed-Cu-HA effectively reduced the extent of inflammatory cell infiltration and bacterial infections in gingival tissues and facilitated the regeneration of periodontal bone tissues and collagen after 2 and 4 weeks of injection. Consequently, it holds significant prospects for future applications in periodontitis treatment.

Quantitatively measuring the cytotoxicity of viscous hydrogels with direct cell sampling in a micro scale format "MicroDrop" and its comparison to CCK8

Tissue engineering holds promise for developing therapeutic applications using viscous materials e.g. hydrogels. However, assessing the cytotoxicity of such materials with conventional assays can be challenging due to non-specific interactions. To address this, we optimized a live/dead staining method for quantitative evaluation and compared it with the conventional CCK8 assay. Our MicroDrop method involved seeding droplets containing 5000 cells in 10 µl medium on 12-well plates. After allowing them to adhere for 4 h, various viscous samples were applied to the cells and measurements were conducted using a fluorescence microscope immediately and at daily intervals up to 72 h. A sodium dodecyl sulfate (SDS) dilution series compared the MicroDrop with the CCK8 assay. The findings revealed a cell-type specific pattern for 10 mg/ml hyaluronic acid (HA), wherein MC3T3-E1 cells maintained 95% viability until 72 h, while L929 cells experienced a gradual decline to 17%. 2 mg/ml HA exhibited consistent viability above 90% across all time points and cell lines. Similarly, fibrin demonstrated 90% viability across dilutions and time points, except for undiluted samples showing a decrease from 85% to 20%. Gelatin-methacrylol sustained viability above 70% across all time points at both 5% and 10% concentrations. The comparison of the SDS dilution series between viability (MicroDrop) and metabolic activity (CCK8) assay showed a correlation coefficient of 0.95. The study validates the feasibility of the established assay, providing researchers with an efficient tool for assessing cytotoxicity in viscous materials. Additionally, it holds the potential to yield more precise data on well-known hydrogels.

In-vitro effects of different hyaluronic acids on periodontal biofilm-immune cell interaction

Introduction

Recent studies have demonstrated a positive role of hyaluronic acid (HA) on periodontal clinical outcomes. This in-vitro study aimed to investigate the impact of four different HAs on interactions between periodontal biofilm and immune cells.

Methods

The four HAs included: high-molecular-weight HA (HHA, non-cross-linked), low-molecular-weight HA (LHA), oligomers HA (OHA), and cross-linked high-molecular-weight HA (CHA). Serial experiments were conducted to verify the influence of HAs on: (i) 12-species periodontal biofilm (formation and pre-existing); (ii) expression of inflammatory cytokines and HA receptors in monocytic (MONO-MAC-6) cells and periodontal ligament fibroblasts (PDLF) with or without exposure to periodontal biofilms; (iii) generation of reactive oxygen species (ROS) in MONO-MAC-6 cells and PDLF with presence of biofilm and HA.

Results

The results indicated that HHA and CHA reduced the bacterial counts in a newly formed (4-h) biofilm and in a pre-existing five-day-old biofilm. Without biofilm challenge, OHA triggered inflammatory reaction by increasing IL-1β and IL-10 levels in MONO-MAC cells and IL-8 in PDLF in a time-dependent manner, whereas CHA suppressed this response by inhibiting the expression of IL-10 in MONO-MAC cells and IL-8 in PDLF. Under biofilm challenge, HA decreased the expression of IL-1β (most decreasing HHA) and increased IL-10 levels in MONO-MAC-6 cells in a molecular weight dependent manner (most increasing CHA). The interaction between HA and both cells may occur via ICAM-1 receptor. Biofilm stimulus increased ROS levels in MONO-MAC-6 cells and PDLF, but only HHA slightly suppressed the high generation of ROS induced by biofilm stimulation in both cells.

Conclusion

Overall, these results indicate that OHA induces inflammation, while HHA and CHA exhibit anti-biofilm, primarily anti-inflammatory, and antioxidant properties in the periodontal environment.

Recent trends in 3D bioprinting technology for skeletal muscle regeneration

Skeletal muscle is a pro-regenerative tissue, that utilizes a tissue-resident stem cell system to effect repair upon injury. Despite the demonstrated efficiency of this system in restoring muscle mass after many acute injuries, in conditions of severe trauma such as those evident in volumetric muscle loss (VML) (>20 % by mass), this self-repair capability is unable to restore tissue architecture, requiring interventions which currently are largely surgical. As a possible alternative, the generation of artificial muscle using tissue engineering approaches may also be of importance in the treatment of VML and muscle diseases such as dystrophies. Three-dimensional (3D) bioprinting has been identified as a promising technique for regeneration of the complex architecture of skeletal muscle. This review discusses existing treatment strategies following muscle damage, recent progress in bioprinting techniques, the bioinks used for muscle regeneration, the immunogenicity of scaffold materials, and in vitro and in vivo maturation techniques for 3D bio-printed muscle constructs. The pros and cons of these bioink formulations are also highlighted. Finally, we present the current limitations and challenges in the field and critical factors to consider for bioprinting approaches to become more translationa and to produce clinically relevant engineered muscle. STATEMENT OF SIGNIFICANCE: This review discusses the physiopathology of muscle injuries and existing clinical treatment strategies for muscle damage, the types of bioprinting techniques that have been applied to bioprinting of muscle, and the bioinks commonly used for muscle regeneration. The pros and cons of these bioinks are highlighted. We present a discussion of existing gaps in the literature and critical factors to consider for the translation of bioprinting approaches and to produce clinically relevant engineered muscle. Finally, we provide insights into what we believe will be the next steps required before the realization of the application of tissue-engineered muscle in humans. We believe this manuscript is an insightful, timely, and instructive review that will guide future muscle bioprinting research from a fundamental construct creation approach, down a translational pathway to achieve the desired impact in the clinic.

Green tea and hyaluronic acid gel enhance fibroblast activation and improves the gingival healing post-third molar extraction

This study evaluates the effects of a green tea (Camellia sinensis) and hyaluronic acid gel on fibroblast activity and alveolar bone repair following third molar extractions. By examining the gene expression related to cell survival, proliferation, and angiogenesis, the study bridges in vitro findings with clinical outcomes in a split-mouth randomized trial. Human fibroblasts were exposed to the treatment gel, analysing gene expression through RT-qPCR. Twenty participants undergoing bilateral third molar extractions received the test gel on one side and a placebo on the other. Assessments included patient-reported outcomes, professional evaluations, and radiographic analyses at multiple postoperative intervals. The test gel significantly enhanced AKT, CDKs, and VEGF gene expressions, indicating a positive effect on angiogenesis and cell proliferation. Clinically, it resulted in reduced exudate, swelling, and secondary interventions, with radiographs showing improved alveolar bone density after 90 days. The green tea and hyaluronic acid gel significantly improves soft tissue and bone healing post-extraction, offering a promising adjunctive therapy for enhancing postoperative recovery. This gel represents a novel adjuvant treatment option for facilitating improved healing outcomes after third molar extractions, highlighting its potential utility in clinical dental practice.

Repeated local delivery of hyaluronic acid gel as adjunctive treatment of residual pockets in periodontitis patients undergoing supportive periodontal care. A randomized controlled clinical trial

OBJECTIVES

To assess the effect of hyaluronic acid (HyA) application as adjunct to re-instrumentation of residual pockets in patients undergoing regular supportive periodontal care (SPC).

METHODS

Chronic periodontitis patients (stage III and IV, grade B and C) with 4 interproximal residual pockets were randomly assigned to the test (HyA gel) or control (saline) group. After subgingival instrumentation, test or control substance was applied subgingivally, then daily supragingivally for 3 months, and if required a second time after subgingival re-instrumentation after 3 months. Clinical and patient reported outcome parameters were recorded every 3 months for 12 months. Pocket closure [probing pocket depth (PPD) ≤ 4mm with absence of bleeding on probing (BoP) at PPD = 4mm] was the main outcome parameter.

RESULTS

Fifty-six patients (221 experimental sites) were analysed. Pocket closure was achieved in 56.8 and 46.6% of the experimental sites in the test and control group, respectively (p > 0.05), while median PPD and PPD distribution (< 5mm/5mm/ > 5mm) differed significantly between groups in favour of the test group, at 12 months. Further, significantly fewer sites in the HyA group required re-instrumentation at 3 months, and sites in the HyA group showed a tendency for lower odds to remain diseased compared to the control group (OR 0.48, 95%CI 0.22-1.06). The odds for a site to remain diseased after 12 months increased significantly in the presence of plaque (OR 7.94, 95%CI 4.12-15.28), but in general, decreased significantly over time (OR 0.48, 95%CI 0.28-0.81).

CONCLUSION

Re-instrumentation of residual pockets in SPC patients, per se, leads to a significant increase in pocket closure over time; this was impeded by poor plaque control. Repeated local application of HyA results in fewer sites requiring re-instrumentation and might slightly improve the rate of pocket closure. (clinicaltrials.gov registration nr. NCT04792541).

CLINICAL RELEVANCE

HyA gel is easy to apply, well accepted by patients, and may have some positive effect in terms of fewer sites requiring re-instrumentation at 3 months and higher pocket closure rate at 12 months.

A literature review of bioactive substances for the treatment of periodontitis: In vitro, in vivo and clinical studies

Periodontitis is a common chronic inflammatory disease of the supporting tissues of the tooth that involves a complex interaction of microorganisms and various cell lines around the infected site. To prevent and treat this disease, several options are available, such as scaling, root planning, antibiotic treatment, and dental surgeries, depending on the stage of the disease. However, these treatments can have various side effects, including additional inflammatory responses, chronic wounds, and the need for secondary surgery. Consequently, numerous studies have focused on developing new therapeutic agents for more effective periodontitis treatment. This review explores the latest trends in bioactive substances with therapeutic effects for periodontitis using various search engines. Therefore, this study aimed to suggest effective directions for therapeutic approaches. Additionally, we provide a summary of the current applications and underlying mechanisms of bioactive substances, which can serve as a reference for the development of periodontitis treatments.

Oxidative stress signaling in the pathogenesis of diabetic cardiomyopathy and the potential therapeutic role of antioxidant naringenin

Diabetes mellitus (DM) is one of the most prevalent metabolic disorders that poses a global threat to human health. It can lead to complications in multiple organs and tissues, owing to its wide-ranging impact on the human body. Diabetic cardiomyopathy (DCM) is a specific cardiac manifestation of DM, which is characterized by heart failure in the absence of coronary heart disease, hypertension and valvular heart disease. Given that oxidative stress is a key factor in the pathogenesis of DCM, intervening to mitigate oxidative stress may serve as a therapeutic strategy for managing DCM. Naringenin is a natural product with anti-oxidative stress properties that can suppress oxidative damage by regulating various oxidative stress signaling pathways. In this review, we address the relationship between oxidative stress and its primary signaling pathways implicated in DCM, and explores the therapeutic potential of naringenin in DCM.

Utilization of experimental design in the formulation and optimization of hyaluronic acid-based nanoemulgel loaded with a turmeric-curry leaf oil nanoemulsion for gingivitis

Numerous problems affect oral health, and intensive research is focused on essential oil-based nanoemulsions that might treat prevent or these problems. Nanoemulsions are delivery systems that enhance the distribution and solubility of lipid medications to targeted locations. Turmeric (Tur)- and curry leaf oil (CrO)-based nanoemulsions (CrO-Tur-self-nanoemulsifying drug delivery systems [SNEDDS]) were developed with the goal of improving oral health and preventing or treating gingivitis. They could be valuable because of their antibacterial and anti-inflammatory capabilities. CrO-Tur-SNEDDS formulations were produced using the response surface Box-Behnken design with different concentrations of CrO (120, 180, and 250 mg), Tur (20, 35, and 50 mg), and Smix 2:1 (400, 500, and 600 mg). The optimized formulation had a bacterial growth inhibition zone of up to 20 mm, droplet size of less than 140 nm, drug-loading efficiency of 93%, and IL-6 serum levels of between 950 ± 10 and 3000 ± 25 U/ml. The optimal formulation, which contained 240 mg of CrO, 42.5 mg of Tur, and 600 mg of Smix 2:1, was created using the acceptable design. Additionally, the best CrO-Tur-SNEDDS formulation was incorporated into a hyaluronic acid gel, and thereafter it had improved ex-vivo transbuccal permeability, sustained in-vitro release of Tur, and large bacterial growth suppression zones. The optimal formulation loaded into an emulgel had lower levels of IL-6 in the serum than the other formulations evaluated in rats. Therefore, this investigation showed that a CrO-Tur-SNEDDS could provide strong protection against gingivitis caused by microbial infections.

In vitro activity of hyaluronic acid and human serum on periodontal biofilm and periodontal ligament fibroblasts

OBJECTIVES

A beneficial effect of cross-linked hyaluronic acid (cHA) on periodontal wound healing and regeneration has recently been demonstrated. The present in vitro study was designed to obtain deeper knowledge on the effect of cHA when applied in the gingival sulcus (serum-rich environment) during non-surgical periodontal therapy.

MATERIALS AND METHODS

The influence of cHA, human serum (HS), and cHA/HS on (i) a 12-species biofilm formation, (ii) the adhesion of periodontal ligament fibroblasts (PDLF) to dentine surface, (iii) the expression and secretion of interleukin-8, and (iv) the expression of receptors of HA in PDLF and gingival fibroblasts (GF) were evaluated.

RESULTS

At 4 h of biofilm formation, cHA and HS in combination (cHA/HS) slightly decreased the colony-forming unit counts in biofilm whereas the metabolic activity of biofilm was reduced in all test groups (cHA, HS, cHA/HS) vs. control. At 24 h, the quantity of biofilm was reduced in all test groups vs. untreated control. The test substances did not affect adhesion of PDLF to dentin. HS increased the expression of IL-8 by PDLF and GF which was partially downregulated by cHA. HS and/or cHA promoted the expression of the HA receptor RHAMM in GF but not in PDLF.

CONCLUSIONS

In summary, the present data indicate that serum neither negatively affect the activity of cHA against periodontal biofilm nor had any unwanted influence on the activity of PDLF.

CLINICAL RELEVANCE

These findings lend additional support for the positive effects of cHA on cells involved in periodontal wound healing, thus pointing to its potential use in non-surgical periodontal therapy.

The Effect of Adjunctive Use of Hyaluronic Acid on Prevalence of Porphyromonas gingivalis in Subgingival Biofilm in Patients with Chronic Periodontitis: A Systematic Review

Porphyromonas gingivalis (P. gingivalis) is a Gram-negative anaerobic bacterium that plays an important role in the development and progression of periodontitis. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan that has previously demonstrated antibacterial potential in vitro against multiple bacterial species, including P. gingivalis. The purpose of this systematic review is to evaluate the effectiveness of HA as an adjunctive topical antibacterial agent to non-surgical mechanical therapy of periodontitis in reducing the prevalence of P. gingivalis in subgingival biofilms. Five clinical studies were identified that satisfied the eligibility criteria. Only three trials were suitable for the meta-analysis as they provided data at three and six months. Data on the prevalence of P. gingivalis in each study were collected. The odds ratio (OR) for measuring the effect size with a 95% confidence interval (CI) was applied to the available data. The results did not favor the use of HA during non-surgical mechanical therapy to reduce the prevalence of P. gingivalis in subgingival biofilm (odd ratio = 0.95 and 1.11 at three and six months, consecutively). Within their limitations, the current data do not indicate an advantage for using HA during mechanical periodontal therapy to reduce the prevalence of P. gingivalis.

Comprehensive review on biosynthesis of hyaluronic acid with different molecular weights and its biomedical applications

Hyaluronic acid (HA), an anionic and nonsulfated glycosaminoglycan, is the main structural component of various tissues and plays an important role in various biological processes. Given the promising properties of HA, such as high cellular compatibility, moisture retention, antiaging, proper interaction with cells, and CD44 targeting, HA can be widely used extensively in drug delivery, tissue engineering, wound healing, and cancer therapy. HA can obtain from animal tissues and microbial fermentation, but its applications depend on its molecular weight. Microbial fermentation is a common method for HA production on an industrial scale and S. zooepidemicus is the most frequently used strain in HA production. Culture conditions including pH, temperature, agitation rate, aeration speed, shear stress, dissolved oxygen, and bioreactor type significantly affect HA biosynthesis properties. In this review all the HA production methods and purification techniques to improve its physicochemical and biological properties for various biomedical applications are discussed in details. In addition, we showed that how HA molecular weight can significantly affect its properties and applications.

Hyaluronic Acid-Based Nanosystems for CD44 Mediated Anti-Inflammatory and Antinociceptive Activity

The nervous and immune systems go hand in hand in causing inflammation and pain. However, the two are not mutually exclusive. While some diseases cause inflammation, others are caused by it. Macrophages play an important role in modulating inflammation to trigger neuropathic pain. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan that has a well-known ability to bind with the cluster of differentiation 44 (CD44) receptor on classically activated M1 macrophages. Resolving inflammation by varying the molecular weight of HA is a debated concept. HA-based drug delivery nanosystems such as nanohydrogels and nanoemulsions, targeting macrophages can be used to relieve pain and inflammation by loading antinociceptive drugs and enhancing the effect of anti-inflammatory drugs. This review will discuss the ongoing research on HA-based drug delivery nanosystems regarding their antinociceptive and anti-inflammatory effects.

High molecular weight hyaluronic acid reduces the growth and biofilm formation of the oral pathogen Porphyromonas gingivalis

Background

Porphyromonas gingivalis (P. gingivalis) is viewed as a keystone microorganism in the pathogenesis of periodontal and peri-implant diseases. Hyaluronic acid (HA) is believed to exert antimicrobial activity. The aim of this study is to assess the in-vitro growth and biofilm formation of P. gingivalis under HA and compare the effect of HA to that of azithromycin (AZM) and chlorhexidine (CHX).

Materials and methods

In each material, the minimum inhibitory concentration (MIC), 50% MIC, 25% MIC, and 12.5% MIC were tested. The growth of P. gingivalis was evaluated by absorbance spectrophotometry after 48 h. A biofilm inhibition assay was performed on a 72-hour culture by washing planktonic bacterial cells, fixing and staining adherent cells, and measuring the variation in stain concentrations relative to the untreated control using absorbance spectrophotometry.

Results

The results show that the overall growth of P. gingivalis after 48 h was 0.048 ± 0.030, 0.008 ± 0.013, and 0.073 ± 0.071 under HA, AZM, and CHX, respectively, while the untreated control reached 0.236 ± 0.039. HA was also able to significantly reduce the biofilm formation of P. gingivalis by 64.30 % ± 22.39, while AZM and CHX reduced biofilm formation by 91.16 %±12.58 and 88.35 %±17.11, respectively.

Conclusions

High molecular-weight HA significantly inhibited the growth of P. gingivalis. The overall effect of HA on the growth of P. gingivalis was similar to that of CHX but less than that of AZM. HA was also able to significantly reduce the biofilm formation of P. gingivalis. However, the ability of HA to prevent the biofilm formation of P. gingivalis was generally less than that of both AZM and CHX.

Lidocaine- and chloramphenicol-loaded nanoparticles embedded in a chitosan/hyaluronic acid/glycerol matrix: Drug-eluting biomembranes with potential for guided tissue regeneration

Guided tissue regeneration (GTR) is a dentistry technique based on the use of polymeric biomembranes as physical barriers for selective cell exclusion, directing the growth of gingival tissue, bone tissue, and periodontal ligaments in a region previously affected by periodontitis. Postoperative pain and microbial infection constitute, however, two major challenges to be tackled right after implantation. To address these challenges, we prepared and characterized eight chitosan/hyaluronic acid/glycerol (CS/HA/GL) bioresorbable membranes embedded with lidocaine- and chloramphenicol-loaded polycaprolactone nanoparticles (LDNP and CHNP, respectively), combining the local anesthetic effects of lidocaine with the antibacterial effects of chloramphenicol. The formulations were prepared with varying amounts of CS, HA, GL, LDNP, and CHNP. As a plasticizing agent, GL could modulate the samples mechanical properties such as thickness, morphology, tensile strength, elongation at break, as well as swelling and degradation in simulated saliva. Two samples exhibited greater resistance to biodegradation and were selected for further studies. Their drug release profiles indicated that LDNP and CHNP first detach from the membrane matrix, and a zeroth order drug release kinetics from the detached NPs dominates the overall process thereafter, with lidocaine being released 3 times faster than chloramphenicol, in a controlled and sustained rate over time. Drug encapsulation efficiency was such that optimal samples exhibited bactericidal activity (inhibition halos) against gram-positive S. aureus and gram-negative A. actinomycetemcomitans strains similar to that observed for free chloramphenicol. Finally, one of these samples showed no intrinsic toxicity against healthy mammalian model cells (99% viability for the unloaded membrane; 80% viability for the fully LDNP- and CHNP-loaded membrane), and may now be further optimized as a drug-eluting biomembrane with potential for GTR.

Advances of Hydrogel Therapy in Periodontal Regeneration-A Materials Perspective Review

Hydrogel, a functional polymer material, has emerged as a promising technology for therapies for periodontal diseases. It has the potential to mimic the extracellular matrix and provide suitable attachment sites and growth environments for periodontal cells, with high biocompatibility, water retention, and slow release. In this paper, we have summarized the main components of hydrogel in periodontal tissue regeneration and have discussed the primary construction strategies of hydrogels as a reference for future work. Hydrogels provide an ideal microenvironment for cells and play a significant role in periodontal tissue engineering. The development of intelligent and multifunctional hydrogels for periodontal tissue regeneration is essential for future research.

High Molecular Weight Hyaluronic Acid Reduces the Expression of Virulence Genes fimA, mfa1, hagA, rgpA, and kgp in the Oral Pathogen Porphyromonas gingivalis

Porphyromonas gingivalis (P. gingivalis) is a cornerstone pathogen in the development and progression of periodontal and peri-implant tissue destruction. It is capable of causing dysbiosis of the microbial biofilm and modulation of the host immune system. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan found in all living organisms. It is well known and has been used for improving tissue healing. In addition, some studies have suggested that there may be an antimicrobial potential to HA. The aim of this study was to evaluate the effect of hyaluronic acid, azithromycin (AZM), and chlorhexidine (CHX) on the expression of genes (i.e., fimA, mfa1, hagA, rgpA, rgpB, and kgp) related to the virulence and adhesion of P. gingivalis. The study groups were divided into four: (1) HA treated group; (2) AZM treated group; (3) CHX treated group; and (4) untreated group to serve as a negative control. P. gingivalis ATCC 33277 was cultured and then exposed to four different concentrations (100% MIC, 50% MIC, 25% MIC, and 12.5% MIC) of HA, AZM, and CHX for 24 h. The expression levels of the aforementioned genes were measured using quantitative reverse transcription polymerase chain reaction (RT-qPCR). Relative fold-change values were calculated and compared between groups. The fold-change values of all genes combined were 0.46 ± 0.33, 0.31 ± 0.24, and 0.84 ± 0.77 for HA, AZM, and CHX, respectively. HA has downregulated all the genes by mostly a half-fold: 0.35 ± 0.20, 0.47 ± 0.35, 0.44 ± 0.25, 0.67 ± 0.46, 0.48 ± 0.33 and 0.35 ± 0.22 with fimA, mfa1, hagA, rgpA, rgpB and kgp, respectively. The effect of HA was significant on all genes except rgpB compared to the untreated control. Lower concentrations of HA tended to exhibit greater downregulation with 1 mg/mL being the most effective. High molecular weight (1.5 MDa) hyaluronic acid has a potent effect on P. gingivalis by downregulating fimA, mfa1, hagA, rgpA, and kgp. The effect of HA was generally less than that of AZM but greater than that of CHX.

Microfluidic-driven mixing of high molecular weight polymeric complexes for precise nanoparticle downsizing

Chitosan (CHIT) and hyaluronic acid (HA) are two polysaccharides (PSs) with high value in several biomedical applications. In this study, we present a microfluidic method to synthetize CHIT-HA NPs to overcome the disadvantages of the dropwise approach generally used for nanoprecipitation of polyelectrolyte complexes. The proposed microfluidic approach enables to generate monodisperse suspensions of NPs with ≈100 nm of size compared to the dropwise method that generated ≈2 times bigger NPs. Finally, we evaluated the potential of obtained NPs in an inflammatory scenario. The treatment with NPs led to the reduction of the main inflammatory molecules produced by macrophages (PGE₂, IL-6, IL-8, MCAF and TNF-α) and fibroblasts (IL-1 α, PGE₂, TNF-α) stimulated with lipopolysaccharide or conditioned medium, respectively. This study demonstrates that our approach can be used to enhance the synthesis of nanocarriers based on bioactive macromolecules.

Lung Hyaluronasome: Involvement of Low Molecular Weight Ha (Lmw-Ha) in Innate Immunity

Hyaluronic acid (HA) is a major component of the extracellular matrix. It is synthesized by hyaluronan synthases (HAS) into high-molecular-weight chains (HMW-HA) that exhibit anti-inflammatory and immunomodulatory functions. In damaged, infected, and/or inflamed tissues, HMW-HA are degraded by hyaluronidases (HYAL) or reactive oxygen species (ROS) to give rise to low-molecular-weight HAs (LMW-HAs) that are potent pro-inflammatory molecules. Therefore, the size of HA regulates the balance of anti- or pro-inflammatory functions. The activities of HA depend also on its interactions with hyaladherins. HA synthesis, degradation, and activities through HA/receptors interactions define the hyaluronasome. In this review, a short overview of the role of high and low-molecular-weight HA polymers in the lungs is provided. The involvement of LMW-HA in pulmonary innate immunity via the activation of neutrophils, macrophages, dendritic cells, and epithelial cells is described to highlight LMW-HA as a therapeutic target in inflammatory respiratory diseases. Finally, the possibilities to counter LMW-HA’s deleterious effects in the lungs are discussed.

Hyaluronic Acid: A Key Ingredient in the Therapy of Inflammation

Hyaluronic acid (HA) is a natural polymer, produced endogenously by the human body, which has unique physicochemical and biological properties, exhibiting desirable biocompatibility and biodegradability. Therefore, it has been widely studied for possible applications in the area of inflammatory diseases. Although exogenous HA has been described as unable to restore or replace the properties and activities of endogenous HA, it can still provide satisfactory pain relief. This review aims to discuss the advances that have been achieved in the treatment of inflammatory diseases using hyaluronic acid as a key ingredient, essentially focusing on studies carried out between the years 2017 and 2021.

Efficacy of hyaluronic acid on intervertebral disc inflammation: An in vitro study using notochordal cell lines and human disc cells

Hyaluronic acid (HA) is widely recognized as a therapeutic target and currently used in medicine. However, HA metabolism during intervertebral disc degeneration (IVDD) has not been completely elucidated. This study aimed to evaluate the efficacy of HA on intervertebral disc (IVD) inflammation and identify the main molecules modulating HA degradation in IVDs. To assess HA function in IVD cells in vitro, we treated human disc cells and U-CH1-N cells, a notochordal nucleus pulposus cell line, with HA or hyaluronidase. Real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis showed that tumor necrosis factor alpha (TNF-α)-mediated induction of the expression of TNF-α and cyclooxygenase-2 (COX2) was clearly neutralized by HA treatment, and the expression of TNF-α and COX2 was significantly induced by hyaluronidase treatment in both cell types. Additionally, Western blot analysis showed that hyaluronidase-induced phosphorylation of p38 and Erk1/2, and that TNF-α-mediated phosphorylation of p38 and Erk1/2 was clearly reduced by HA addition. In degenerating human IVD samples, immunohistochemistry for hyaluronidase showed that the expression of hyaluronidases including HYAL1, HYAL2, and cell migration-inducing protein (CEMIP) tended to increase in accordance with IVDD. In particular, HYAL1 showed statistically significant differences. In vitro study also confirmed a similar phenomenon that TNF-α treatment increased both messenger RNA and protein expression in both cell types. Our results demonstrated that HA could potentially suppress IVDD by regulating p38 and Erk1/2 pathways, and that the expression of HYAL1 was correlated with IVDD progression. These findings indicated that HYAL1 would be a potential molecular target for suppressing IVDD by controlling HA metabolism.

Hyaluronic Acid Increases Anti-Inflammatory Efficacy of Rectal 5-Amino Salicylic Acid Administration in a Murine Colitis Model

5-amino salicylic acid (5-ASA) is a standard therapy for the treatment of mild to moderate forms of inflammatory bowel diseases (IBD) whereas more severe forms involve the use of steroids and immunosuppressive drugs. Hyaluronic acid (HA) is a naturally occurring non-sulfated glycosaminoglycan that has shown epithelium protective effects in experimental colitis recently. In this study, both 5-ASA (30 mg/kg) and HA (15 mg/kg or 30 mg/kg) were administered rectally and investigated for their potential complementary therapeutic effects in moderate or severe murine colitis models. Intrarectal treatment of moderate and severe colitis with 5-ASA alone or HA alone at a dose of 30 mg/kg led to a significant decrease in clinical activity and histology scores, myeloperoxidase activity (MPO), TNF-α, IL-6 and IL-1β in colitis mice compared to untreated animals. The combination of HA (30 mg/kg) and 5-ASA in severe colitis led to a significant improvement of colitis compared to 5-ASA alone. Combined rectal therapy with HA and 5-ASA could be a treatment alternative for severe cases of IBD as it was the only treatment tested that was not significantly different from the healthy control group. This study further underlines the benefit of searching for yet unexplored drug combinations that show therapeutic potential in IBD without the need of designing completely new drug entities.

4-Methylumbelliferone promotes the migration and odontogenetic differentiation of human dental pulp stem cells exposed to lipopolysaccharide in vitro

Hyaluronic acid (HA), a major component of the extracellular matrix, is essential to inflammatory regulation. 4-Methylumbelliferone (4-mu), as the specific inhibitor of HA synthesis, is an anti-inflammatory in multiple systems. However, there have been no studies, to our knowledge, regarding 4-mu treatment in pulp inflammation. Therefore, the purpose of this study was to investigate the effects of 4-mu on biological behaviors in human dental pulp stem cells (hDPSCs) exposed to lipopolysaccharide (LPS) in vitro. hDPSCs were exposed to LPS to construct the inflammation model in vitro. Immunocytochemistry, quantitative polymerase chain reaction, western blotting, Cell Counting Kit-8, scratch/Transwell assay, and alizarin red staining/alkaline phosphatase staining were selected to explore the effect of 4-mu on the expression of inflammatory factors, cell proliferation, cell migration, and the odontogenic differentiation ability of hDPSCs. LPS stimulated hDPSCs to highly express the related inflammatory factors and CD44 (the major HA receptor), which were all inhibited by 0.1 mM of 4-mu. In addition, the cell proliferation ability of hDPSCs was suppressed by 4-mu, while cell migration and odontogenic differentiation abilities were significantly improved under inflammation. In conclusion, 4-mu suppressed inflammatory cytokines in inflamed hDPSCs and had a positive effect on the migration and odontogenic differentiation of hDPSCs.

Hemostatic performance of chitosan-based hydrogel and its study on biodistribution and biodegradability in rats

Hemostasis is of great significance regardless of the smooth operation or postoperative recovery. Therefore, it is urgent to develop a hemostatic material with excellent biodegradability and biocompatibility. It is well known that both carboxymethyl chitosan and hyaluronic acid with biodegradability and biocompatibility have wound healing promoting property. Here, a degradable chitosan-based hydrogel was prepared based on carboxymethyl chitosan and cross-linked by oxidized hyaluronic acid. The hemostatic performance of the hydrogel in rat liver resection injury was evaluated which results showed that the hydrogel exhibited comparable hemostatic properties compared with Fibrin Sealant. In addition, the hydrogel proved to be rapidly absorbed by the body without significant accumulation in vivo, demonstrating good biodegradability and biocompatibility. The overall results suggested the hydrogel will be a promising hemostatic hydrogel for controlling bleeding.

Co-implantation of magnesium and zinc ions into titanium regulates the behaviors of human gingival fibroblasts

Soft tissue sealing around implants acts as a barrier between the alveolar bone and oral environment, protecting implants from the invasion of bacteria or external stimuli. In this work, magnesium (Mg) and zinc (Zn) are introduced into titanium by plasma immersed ion implantation technology, and their effects on the behaviors of human gingival fibroblasts (HGFs) as well as the underlying mechanisms are investigated. Surface characterization confirms Mg and Zn exist on the surface in metallic and oxidized states. Contact angle test suggests that surface wettability of titanium changes after ion implantation and thus influences protein adsorption of surfaces. In vitro studies disclose that HGFs on Mg ion-implanted samples exhibit better adhesion and migration while cells on Zn ion-implanted samples have higher proliferation rate and amounts. The results of immunofluorescence staining and real-time reverse-transcriptase polymerase chain reaction (RT-PCR) suggest that Mg mainly regulates the motility and adhesion of HGFs through activating the MAPK signal pathway whereas Zn influences HGFs proliferation by triggering the TGF-β signal pathway. The synergistic effect of Mg and Zn ions ensure that HGFs cultured on co-implanted samples possessed both high proliferation rate and motility, which are critical to soft tissue sealing of implants.

Recent Advances in Antiinflammatory Material Design

Implants and prostheses are widely used to replace damaged tissues or to treat various diseases. However, besides the risk of bacterial or fungal infection, an inflammatory response usually occurs. Here, recent progress in the field of anti-inflammatory biomaterials is described. Different materials and approaches are used to decrease the inflammatory response, including hydrogels, nanoparticles, implant surface coating by polymers, and a variety of systems for anti-inflammatory drug delivery. Complex multifunctional systems dealing with inflammation, microbial infection, bone regeneration, or angiogenesis are also described. New promising stimuli-responsive systems, such as pH- and temperature-responsive materials, are also being developed that would enable an "intelligent" antiinflammatory response when the inflammation occurs. Together, different approaches hold promise for creation of novel multifunctional smart materials allowing better implant integration and tissue regeneration.

Hyaluronan alkyl derivatives-based electrospun membranes for potential guided bone regeneration: Fabrication, characterization and in vitro osteoinductive properties

The aim of the work was to determine the effects of the chemical functionalization of hyaluronic acid (HA) with pendant aliphatic tails at different lengths and free amino groups in terms of chemical reactivity, degradation rate, drug-eluting features, and surface properties when processed as electrospun membranes (EM) evaluating the osteoinductive potential for a possible application as guided bone regeneration (GBR). To this end, a series of HA derivatives with different aliphatic tails (DD-Cx mol% ≈ 12.0 mol%) and decreasing derivatization of free amino groups (DD_EDA mol% from 70.0 to 30.0 mol%) were first synthesized, namely Hn. Then dexamethasone-loaded Hn EM, i.e. HnX were prepared from aqueous polymeric solutions with polyvinyl alcohol (PVA), as a non-ionogenic linear flexible polymeric carrier, and the multifunctional 2-hydroxypropyl- cyclodextrin (HPCD) which acted as a rheological modifier, a stabilizer of Taylor's cone, and a solubilizing agent. A comprehensive characterization of the membranes was carried out through ATR-IR, XRD, and WCA measurements. According to the in vitro hydrolytic and enzymatic degradation and drug release in different aqueous media for two months, the insertion of alkyl pendant grafts and the crosslinking process provided tuneable additional resistance to the whole membrane suitably for the final application of the membranes. Cell culture showed the cytocompatibility and cell proliferation until 7 days. Osteogenic differentiation and mineralization of pre-osteoblastic MC3T3 cells occurred for most of membranes after 35 days as valued by measuring ALP activity (50 nmol 4-np/h/nf DNA) and the deposition of calcium (120-140 μg ml^-1).

Impact of Attrition, Intercellular Shear in Dry Eye Disease: When Cells are Challenged and Neurons are Triggered

The mechanical component in the pathophysiology of dry eye disease (DED) deserves attention as an important factor. The lubrication deficit induced impaired mechano-transduction of lid pressure to the ocular surfaces may lead to the dysregulation of homeostasis in the epithelium, with sensations of pain and secondary inflammation. Ocular pain is possibly the first sign of attrition and may occur in the absence of visible epithelial damage. Attrition is a process which involves the constant or repeated challenge of ocular surface tissues by mechanical shear forces; it is enhanced by the thinning of corneal epithelium in severe DED. As a highly dynamic process leading to pain and neurogenic inflammation, the identification of the impact of attrition and its potential pathogenic role could add a new perspective to the current more tear film-oriented models of ocular surface disease. Treatment of DED addressing lubrication deficiencies and inflammation should also consider the decrease of attrition in order to stimulate epithelial recovery and neural regeneration. The importance of hyaluronic acid, its molecular characteristics, the extracellular matrix and autoregulative mechanisms in this process is outlined. The identification of the attrition and recognition of its impact in dry eye pathophysiology could contribute to a better understanding of the disease and optimized treatment regimens.

Antimicrobial efficacy of 0.8% Hyaluronic Acid and 0.2% Chlorhexidine against Porphyromonas gingivalis strains: An in-vitro study

Objective:

The aim of the present in-vitro study was to assess antimicrobial efficacy of 0.8% hyaluronic acid (HA) and 0.2% Chlorhexidine gluconate (CHX) against Porphyromonas gingivalis (P. gingivalis).

Methods:

The study was performed between December 2018 and March 2019 at the College of Dentistry at the Princess Nourah Bint Abdulrahman University, Riyadh, Saudi Arabia. The P. gingivalis biofilms were formed and grown for 72 hours at 37°C under anaerobic conditions on glass slides coated with human saliva. The slides were individually positioned and exposed to 0.8% HA or 0.2% CHX. Therapeutically, the biofilms were divided into 3 groups as follows: (a) negative group; (b) 0.8% HA group and (c) 0.2% CHX group. P-values less than 0.05 were considered statistically significant.

Results:

In the 0.8% HA group, P. gingivalis CFUs/ml were significantly higher at baseline than at 24- (P<0.05), 48 (P<0.05) and 72 hours (P<0.05) intervals. In the 0.2% CHX group, P. gingivalis CFUs/ml were significantly higher at baseline than at 72 hours interval (P<0.05). In the CHX group, there was no difference in P. gingivalis CFUs/ml between baseline, 24- and 48-hours intervals. At 48- and 72-hours intervals, the P. gingivalis CFUs/ml were significantly higher in the 0.2% CHX group compared with the 0.8% HA group.

Conclusion:

In-vitro, 0.8% HA is more effective in reducing the P. gingivalis CFUs/ml compared with 0.2% CHX.

A Hyaluronan-binding Peptide (P15-1) Reduces Inflammatory and Catabolic Events in IL-1β-treated Human Articular Chondrocytes

Inflammation plays a critical role in osteoarthritis (OA). It stimulates catabolic events in articular chondrocytes and prevents chondrogenic precursor cells from repairing cartilage lesions, leading to accelerated cartilage degradation. Therefore, the identification of novel factors that reduce catabolic events in chondrocytes and enhances chondrogenic differentiation of precursor cells in an inflammatory environment may provide novel therapeutic strategies for the treatment of OA. The goal of this study was to determine whether a hyaluronan (HA)-binding peptide (P15-1), via interacting with high molecular weight (HMW)HA can enhance the anti-inflammatory properties of HMWHA and decrease catabolic events in interleukin-1beta (IL-1β)-treated human articular chondrocytes. Treatment with P15-1 decreased catabolic events and stimulated anabolic events in articular chondrocytes cultured in an inflammatory environment. P15-1 pre-mixed with HMWHA was more effective in inhibiting catabolic events and stimulating anabolic events than P15-1 or HMWHA alone. Our findings suggest that P15-1 together with HMWHA inhibits catabolic events in articular chondrocytes via the inhibition of p38 mitogen-activated protein kinases (MAPK) and increasing the thickness of the pericellular matrix (PCM) around chondrocytes thereby decreasing catabolic signaling. Finally, conditioned medium from IL-1β and P15-1-treated human articular chondrocytes was less inhibitory for chondrogenic differentiation of precursor cells than conditioned medium from chondrocytes treated with IL-1β alone. In conclusion, P15-1 is proposed to function synergistically with HMWHA to enhance the protective microenvironment for chondrocytes and mesenchymal stem cells during inflammation and regeneration.

Study on the potential mechanism of anti-inflammatory activity of covalently immobilized hyaluronan and heparin

Inflammation and subsequent fibrotic encapsulation that occur after implantation of biomaterials are issues that fostered efforts in designing novel biocompatible materials to modulate the immune response. In this study, glycosaminoglycans (GAG) like hyaluronic acid (HA) and heparin (Hep) that possess anti-inflammatory activity were covalently bound to NH₂ -modified surfaces using EDC/NHS cross-linking chemistry. Immobilization and physical surface properties were characterized by atomic forces microscopy, water contact angle studies and streaming potential measurements demonstrating the presence of GAG on the surfaces that became more hydrophilic and negatively charged compared to NH₂ -modified. THP-1 derived macrophages were used here to study the mechanism of action of GAG to affect the inflammatory responses illuminated by studying macrophage adhesion, the formation of multinucleated giant cells (MNGCs) and IL-1β release that were reduced on GAG-modified surfaces. Detailed investigation of the signal transduction processes related to macrophage activation was performed by immunofluorescence staining of NF-κB (p65 subunit) together with immunoblotting. We studied also association and translocation of FITC-labeled GAG. The results show a significant decrease in NF-κB level as well as the ability of macrophages to associate with and take up HA and Hep. These results illustrate that the anti-inflammatory activity of GAG is not only related to making surfaces more hydrophilic, but also their active involvement in signal transduction processes related to inflammatory reactions, which may pave the way to design new anti-inflammatory surface coatings for implantable biomedical devices.

The possible role of basic fibroblast growth factor in dental pulp

Fibroblast growth factors (FGFs) are growth factors that play an important role in tooth development, repair, and regeneration. Of the FGF families, basic fibroblast growth factor (bFGF) has been the most frequently investigated in dentistry. Numerous studies have reported advantages of bFGF, while others did not find any additional benefit. This review gives a comprehensive summary of the potential role of bFGF in dental pulp wound healing and regeneration in connection with cell proliferation and differentiation, angiogenesis, and neural differentiation from both in vitro and in vivo studies. Furthermore, the possible underlying mechanisms associated with bFGF in promoting dental pulp wound healing are discussed in this review.

Hyaluronic acid and chitosan-based nanosystems: a new dressing generation for wound care

INTRODUCTION

The main goal in the management of chronic wounds is the development of multifunctional dressings able to promote a rapid recovery of skin structure and function, improving patient compliance.

AREAS COVERED

This review discusses the use of nanosystems, based on hyaluronic acid and chitosan or their derivatives for the local treatment of chronic wounds. The bioactive properties of both polysaccharides will be described, as well as the results obtained in the last decade by the in vitro and in vivo evaluation of the wound healing properties of nanosystems based on such polymers.

EXPERT OPINION

In the last decades, there has been a progressive change in the local treatments of chronic wounds: traditional inert dressings have been replaced by more effective bioactive ones, based on biopolymers taking part in wound healing and able to release the loaded active agents in a controlled way. With the advance of nanotechnologies, the scenario has further changed: nanosystems, characterized by a large area-to-volume ratio, show an improved interaction with the biological substrates, amplifying the activity of the constituent biopolymers. In the coming years, a deeper insight into wound healing mechanisms and the development of new techniques for nanosystem manufacturing will results in the design of new scaffolds with improved performance.