Injectable Hyaluronic Acid Hydrogel Research Articles

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.

Effect of quince seed gum (QSG) on the performance of injectable hyaluronic acid hydrogels in terms of the rheological, morphological, and mechanical aspect.

Injectable hydrogels play an important role in tissue engineering as a filling and repairing material. This study aimed to develop a new injectable hydrogel based on hyaluronic acid (HA) and quince seed gum (QSG) and investigate the effect of QSG on hydrogel performance. The amount of unreacted 1,4-Butanediol diglycidyl ether is maintained at an undetectable level for HA-QSG hydrogels. Amino acid analysis showed that the HA-QSG hydrogel had rich amino acid concentrations of leucine, arginine, and valine. After thermal sterilization, the elastic modulus of HA-QSG gels for dermal and intraarticular filler applications is 63 Pa and 92 Pa, respectively. Pore size was found below 200 μm and the dense homogeneous pore structure was observed.

Hyaluronic acid hydrogel to modulate tumor cell clustering and programmed death ligand 1 signaling in cancer stem cells.

e14584 Background: The root of malignancy lies in the extracellular matrix (ECM) surrounding the stromal cells. Thus, current therapeutic targets manipulate abnormal tumor microenvironments (TME), which nourish cancer stem cells (CSC) and induce tumor cell clustering (TCC). Notably, despite the first line of clinical therapy with surgery and chemotherapy, uncontrolled self-renewal of CSCs, conversion of non-CSCs to CSCs, and TCC trigger cancer recurrence. The transmembrane glycoprotein CD44 is thought to be a potential master regulator in cancer recurrence as it interacts with hyaluronic acid (HA) in TME, expresses aberrantly on CSCs, induces TCC by homophilic interactions like Plakoglobin despite less understanding on their crosstalk, and promotes expression of pro-tumorigenic factor programmed death ligand 1 (PD-L1). Notably, CD44 is expressed in multiple isoforms, and splice isoform switching of CD44 dictates the properties of CSC, which still needs to be clarified. Hence, we aimed to characterize CSCs based on CD44 isoform expression, investigate the crosstalk between CD44 and Plakoglobin, and then design a novel injectable HA hydrogel that can disguise TME and suppress PD-L1 to combat cancer recurrence. Methods: To characterize CSCs, we prepared different scaffolds of HA of varied molecular weights and other ECM proteins, cultured cancer cells (MDA-MB-231, HeLa), and determined the expression of CD44 isoforms. We sorted CD44+/CD24- expressing CSC by flow cytometry. We implemented immunoprecipitation to detect the interaction between CD44 and Plakoglobin. We created a novel HA hydrogel composed of low and very high molecular weight HA, thiolated gelatin, and other components crosslinked with PEGDA. Using a torsional rheometer, we measured matrix stiffness. We assessed the cell proliferation efficiency of CSC by a colony-forming assay. Results: The study disclosed that CD44 isoforms expressed differently based on ECM properties. Matrix stiffness dictated CD44 isoform expression. We observed that CD44 interacted with Plakoglobin. CD44 ablation upregulated Plakoglobin significantly. Tumor suppressor p53 played a significant role in CD44-Plakoglobin crosstalk. We observed that the injectable hydrogel modulated CD44-Plakoglobin signaling and inhibited TCC, likely promoting anoikis. The hydrogel affected CD44 splicing and modified the activity of the CD44 intracellular domain, which interacts with PD-L1 and thus suppressed PD-L1 expression significantly in CSC. Conclusions: Currently, antibodies targeting PD-1/PD-L1 signaling have been clinically approved for various cancers. However, this regimen of treatment is expensive. We report a novel injectable hydrogel that can disguise TME, modulate CSCs and PD-L1, and may advance an alternative cost-effective avenue for cancer immunotherapy.

In situ forming an injectable hyaluronic acid hydrogel for drug delivery and synergistic tumor therapy

Stimulus-responsive injectable hydrogel has the key characteristics of in situ drug-loading ability and the controlled drug release, enabling efficient delivery and precise release of chemotherapy drugs at the tumor site, thereby being used as a local drug delivery system for sustained tumor treatment. This article designed a smart responsive injectable hydrogel loaded with anti-tumor drugs and nanoparticles to achieve efficient and specific synergistic treatment of tumors. Hyaluronic acid (HA) hydrogel obtained by cross-linking HA-SH (HS) and HA-Tyr (HT) through horseradish peroxidase (HRP), and doxorubicin hydrochloride (DOX) and folic acid-polyethylene glycol-amine (FA-PEG-NH2) modified PDA (denoted as PPF) were encapsulated to construct the HS/HT@PPF/D hydrogel. The hydrogel had good biocompatibility, injectability, and could respond to multiple stimuli at the tumor site, thereby achieving controlled drug release. At the same time, PPF gave it excellent photothermal efficiency, photothermal stability and tumor targeting. In vitro and in vivo experimental results showed that the HS/HT@PPF/D hydrogel combined with near-infrared laser irradiation could significantly improve its anti-tumor effect and could almost eliminate the entire tumor mass without obvious adverse reactions. The HS/HT@PPF/D hydrogel could achieve multi-stimulus-responsive drug delivery and be used for precise chemo-photothermal synergistic tumor treatment, thus providing a new platform for local synergistic tumor treatment.

Exploring the Formulation and Approaches of Injectable Hydrogels Utilizing Hyaluronic Acid in Biomedical Uses.

The characteristics of injectable hydrogels make them a prime contender for various biomedical applications. Hyaluronic acid is an essential component of the matrix surrounding the cells; moreover, hyaluronic acid's structural and biochemical characteristics entice researchers to develop injectable hydrogels for various applications. However, due to its poor mechanical properties, several strategies are used to produce injectable hyaluronic acid hydrogel. This review summarizes published studies on the production of injectable hydrogels based on hyaluronic acid polysaccharide polymers and the biomedical field's applications for these hydrogel systems. Hyaluronic acid-based hydrogels are divided into two categories based on their injectability mechanisms: in situ-forming injectable hydrogels and shear-thinning injectable hydrogels. Many crosslinking methods are used to create injectable hydrogels; chemical crosslinking techniques are the most frequently investigated technique. Hybrid injectable hydrogel systems are widely investigated by blending hyaluronic acid with other polymers or nanoparticulate systems. Injectable hyaluronic acid hydrogels were thoroughly investigated and proven to demonstrate potential in various medical fields, including delivering drugs and cells, tissue repair, and wound dressings.

Preparation of Short Collagen Nanofibers for Injectable Hydrogels: Comparative Assessment of Fragmentation Methods, Physicomechanical Properties, and Biocompatibility

AbstractCollagen nanofibers can be employed in hydrogels to create injectable nanocomposite hydrogels, mimicking the fibrous architecture of the natural extracellular matrix (ECM). As long continuous electrospun collagen nanofibers are not applicable, fragmentation is inevitable to obtain injectable hydrogels with a fine viscosity. Here, four methods: hand grinding (HG), homogenizer (HM), mixer milling (MM), and ultrasonication (UH) are used to disintegrate and shorten collagen nanofiber mats before incorporation into an injectable hyaluronic acid hydrogel as a matrix. The Length‐to‐diameter (L/d) ratio and morphology of fragmented collagen are compared by SEM. The injection force, mechanical properties, and cell viability of the selected collagen‐incorporated hydrogels are also evaluated. UH emerges as the most effective method, yielding the highest L/d ratio of 46 and a notable compressive modulus of 8.7 ± 0.92 kPa. Assessment of the in vitro cell viability of the encapsulated chondrocytes in the collagen‐incorporated hydrogels demonstrates good biocompatibility, and hydrogels containing UH short nanofiber, in particular, show an increase in cell proliferation. This work indicates how collagen mats can be effectively broken down and combined with injectable hydrogels to enhance both their mechanical behavior and biocompatibility.

Biphasic release of betamethasone from an injectable HA hydrogel implant for alleviating lumbar disc herniation induced sciatica

Epidural steroid injection (ESI) is a common therapeutic approach for managing sciatica caused by lumbar disc herniation (LDH). However, the short duration of therapeutic efficacy and the need for repeated injections pose challenges in LDH treatment. The development of a controlled delivery system capable of prolonging the effectiveness of ESI and reducing the frequency of injections, is highly significant in LDH clinical practice. In this study, we utilized a thiol-ene click chemistry to create a series of injectable hyaluronic acid (HA) based release systems loaded with diphasic betamethasone, including betamethasone dipropionate (BD) and betamethasone 21-phosphate disodium (BP) (BD/BP@HA). BD/BP@HA hydrogel implants demonstrated biocompatibility and biodegradability to matched neuronal tissues, avoiding artificial compression following injection. The sustained release of betamethasone from BD/BP@HA hydrogels effectively inhibited both acute and chronic neuroinflammation by suppressing the nuclear factor kappa-B (NF-κB) pathway. In a mouse model of LDH, the epidural administration of BD/BP@HA efficiently alleviated LDH-induced sciatica for at least 10 days by inhibiting the activation of macrophages and microglia in dorsal root ganglion and spinal dorsal horn, respectively. The newly developed HA hydrogels represent a valuable platform for achieving sustained drug release. Additionally, we provide a simple paradigm for fabricating BD/BP@HA for epidural injection, demonstrating greater and sustained efficiency in alleviating LDH-induced sciatica compared to traditional ESI and displaying potentials for clinical translation. This system has the potential to revolutionize drug delivery for co-delivery of both soluble and insoluble drugs, thereby making a significant impact in the pharmaceutical industry. Statement of SignificanceLumbar disc herniation (LDH) is a common degenerative disorder leading to sciatica and spine surgery. Although epidural steroid injection (ESI) is routinely used to alleviate sciatica, the efficacy is short and repeated injections are required. There remains challenging to prolong the efficacy of ESI. Herein, an injectable hyaluronic acid (HA) hydrogel implant by crosslinking acrylated-modified HA (HA-A) with thiol-modified HA (HA-SH) was designed to achieve a biphasic release of betamethasone. The hydrogel showed biocompatibility and biodegradability to match neuronal tissues. Notably, compared to traditional ESI, the hydrogel better alleviated sciatica in vivo by synergistically inhibiting the neuroinflammation in central and peripheral nervous systems. We anticipate the injectable HA hydrogel implant has the potential for clinical translation in treating LDH-induced sciatica.

Anti-osteoarthritis effects of injectable hyaluronic acid hydrogel loaded with platelet lysate and cerium oxide nanoparticle by regulating TNF-α: An in vitro model

The most prevalent type of joint illness is osteoarthritis, also known as OA. The inflammation of the joint is strongly linked to both the beginning and the progression of osteoarthritis. The use of hydrogels as an OA treatment has the potential to go beyond the administration of anti-inflammatory components to have an inherent immunomodulatory role. Platelet lysate (PL) contains a cocktail of growth factors that actively participates in cartilage repair. Moreover, cerium oxide-nanoparticles (CeO2-NPs) have been broadly studied owing to their powerful antioxidant properties and potential preventive and therapeutic effects against chronic diseases. The current study was designed to determine the effect and mechanism of injectable hyaluronic acid (HA) hydrogel loaded with PL and CeO2-NPs on OA. The results showed that the obtained PL and synthesized CeO2-NPs were effectively incorporated into HA hydrogel and the resultant hydrogel was injectable and have a porous micro structure with interconnected pores. The biological evaluation by qPCR revealed that the fabricated hydrogel exhibited a significantly increased expression of Col2 and Aggrecan (TNF-α-suppressed anabolic molecules) and decreased expression of Col10, Mmp13, Adamts5, and Adamts9 (TNF-α-activated catabolic molecules). Also, ELISA results confirmed this potent antioxidant activity of hydrogel and also increased the growth of chondrocytes over the culturing period.

Mesenchymal Stem Cells Delivered Locally to Ischemia-Reperfused Kidneys via Injectable Hyaluronic Acid Hydrogels Decrease Extracellular Matrix Remodeling 1 Month after Injury in Male Mice.

The translation of stem cell therapies has been hindered by low cell survival and retention rates. Injectable hydrogels enable the site-specific delivery of therapeutic cargo, including cells, to overcome these challenges. We hypothesized that delivery of mesenchymal stem cells (MSC) via shear-thinning and injectable hyaluronic acid (HA) hydrogels would mitigate renal damage following ischemia-reperfusion acute kidney injury. Acute kidney injury (AKI) was induced in mice by bilateral or unilateral ischemia-reperfusion kidney injury. Three days later, mice were treated with MSCs either suspended in media injected intravenously via the tail vein, or injected under the capsule of the left kidney, or MSCs suspended in HA injected under the capsule of the left kidney. Serial measurements of serum and urine biomarkers of renal function and injury, as well as transcutaneous glomerular filtration rate (tGFR) were performed. In vivo optical imaging showed that MSCs localized to both kidneys in a sustained manner after bilateral ischemia and remained within the ipsilateral treated kidney after unilateral ischemic AKI. One month after injury, MSC/HA treatment significantly reduced urinary NGAL compared to controls; it did not significantly reduce markers of fibrosis compared to untreated controls. An analysis of kidney proteomes revealed decreased extracellular matrix remodeling and high overlap with sham proteomes in MSC/HA-treated animals. Hydrogel-assisted MSC delivery shows promise as a therapeutic treatment following acute kidney injury.

Injectable Hyaluronic Acid Hydrogel Containing Platelet Derivatives for Synovial Fluid Viscosupplementation and Growth Factors Delivery.

Osteoarthritisis a highly prevalent musculoskeletal disorder characterized by degradation of cartilage and synovial fluid (SF). Platelet derivatives as platelet-rich plasma (PRP) and platelet lysate have great potential in the treatment of osteoarthritis because they contain biologically active substances including growth factors (GFs). Rapid release of GFs and their short biological half-life are factors that can limit the therapeutic impact of PRP therapy. Herein, the first work that describes hydrogels based on polyaldehyde derivative of hyaluronic acid (HA-OX) as carriers of platelet derivatives for in situ applications is presented, which can be a possible solution to the problem. HA-OX hydrogels containing 50% (w/w) of PRP or platelet lysate can be injected using a syringe due to low viscosity(<10Pas) and injection force (<20N), and reach elastic modulus up to 2000Pa. Insulin-like GF-1 and Platelet-derived GF-AB release from HA-OX hydrogels (mesh size 297-406 nm) by Fickian and non-Fickian diffusion respectively. The released PRP GFs maintain their ability to induce cell proliferation (87%-92%). Based on the obtained results, the unique concept of a new material that can restore viscoelastic properties of SF and at the same time gradually deliver GFs from platelet derivatives is designed.

Functionalized injectable hyaluronic acid hydrogel with antioxidative and photothermal antibacterial activity for infected wound healing

Infected wound healing has always been a challenge in clinic. Effective and economic wound dressings with combined antibacterial activity and pro-healing function are highly desirable, especially in the context of infected wounds. An obvious advantage of antibacterial wound dressing is to avoid the overuse of antibiotics and the occurrence of drug resistance. Herein, an injectable hyaluronic acid hydrogel with antioxidative and photothermal antibacterial activity as a functional dressing was prepared, characterized and evaluated in an experimental infected wound model. This hydrogel was developed by loading graphene oxide (GO) in a natural polymer network consisting of hyaluronic acid grafted with tyramine (HT) and gelatin grafted with gallic acid (GGA). The HT/GGA/GO hydrogels have a porous cross-linked network structure and demonstrate a good stability, biocompatibility, antioxidant, hemostatic and photothermal antibacterial activity against Escherichia coli and Staphylococcus aureus. In addition, in vivo studies have shown that HT1/GGA2/GO0.1 hydrogel dressing combined with photothermal therapy can effectively prevent early infection and accelerate wound healing. These results indicated this functionalized injectable hydrogel HT1/GGA2/GO0.1 has a great potential in wound dressing application.

MSC-derived sEV-loaded hyaluronan hydrogel promotes scarless skin healing by immunomodulation in a large skin wound model

Designing hydrogel-based constructs capable of adjusting immune cell functions holds promise for skin tissue regeneration. Mesenchymal stem cell (MSC)-derived small extracellular vesicles (sEVs) have attracted increasing attention owing to their anti-inflammatory and proangiogenic effects. Herein, we constructed a biofunctional hydrogel in which MSC-derived sEVs were incorporated into the injectable hyaluronic acid hydrogel, thus endowing the hydrogel with immunomodulatory effects. When implanted onto the wound site in a mouse large skin injury model, this functional hydrogel facilitates wound healing and inhibits scar tissue formation by driving macrophages towards an anti-inflammatory and anti-fibrotic (M2c) phenotype. Further investigation showed that the M2c-like phenotype induced by MSC-derived sEVs markedly inhibited the activation of fibroblasts, which could result in scarless skin wound healing. Taken together, these results suggest that modulation of the immune response is a promising and efficient approach to prevent fibrotic scar formation.

Injectable hyaluronic acid hydrogel encapsulated with Si-based NiO nanoflower by visible light cross-linking: Its antibacterial applications

Bacterial infections have become a severe threat to human health and antibiotics have been developed to treat them. However, extensive use of antibiotics has led to multidrug-resistant bacteria and reduction of their therapeutic effects. An efficient solution may be localized application of antibiotics using a drug delivery system. For clinical application, they need to be biodegradable and should offer a prolonged antibacterial effect. In this study, a new injectable and visible-light-crosslinked hyaluronic acid (HA) hydrogel loaded with silicon (Si)-based nickel oxide (NiO) nanoflowers (Si@NiO) as an antibacterial scaffold was developed. Si@NiO nanoflowers were synthesized using chemical bath deposition before encapsulating them in the HA hydrogel under a mild visible-light-crosslinking conditions to generate a Si@NiO-hydrogel. Si@NiO synthesis was confirmed using scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction. As-prepared Si@NiO-hydrogel exhibited enhanced mechanical properties compared to a control bare hydrogel sample. Moreover, Si@NiO-hydrogel exhibits excellent antibacterial properties against three bacterial strains (P. aeruginosa, K. pneumoniae, and methicillin-resistant Staphylococcus aureus (>99.9% bactericidal rate)) and negligible cytotoxicity toward mouse embryonic fibroblasts. Therefore, Si@NiO-hydrogel has the potential for use in tissue engineering and biomedical applications owing to its injectability, visible-light crosslink ability, degradability, biosafety, and superior antibacterial property.

Injectable hyaluronic acid hydrogel loaded with BMSC and NGF for traumatic brain injury treatment.

Injectable hydrogel has the advantage to fill the defective area and thereby shows promise as therapeutic implant or cell/drug delivery vehicle for tissue repair. In this study, an injectable hyaluronic acid hydrogel in situ dual-enzymatically cross-linked by galactose oxidase (GalOx) and horseradish peroxidase (HRP) was synthesized and optimized, and the therapeutic effect of this hydrogel encapsulated with bone mesenchymal stem cells (BMSC) and nerve growth factors (NGF) for traumatic brain injury (TBI) mice was investigated. Results from in vitro experiments showed that either tyramine-modified hyaluronic acid hydrogels (HT) or NGF loaded HT hydrogels (HT/NGF) possessed good biocompatibility. More importantly, the HT hydrogels loaded with BMSC and NGF could facilitate the survival and proliferation of endogenous neural cells probably by neurotrophic factors release and neuroinflammation regulation, and consequently improved the neurological function recovery and accelerated the repair process in a C57BL/6 TBI mice model. All these findings highlight that this injectable, BMSC and NGF-laden HT hydrogel has enormous potential for TBI and other tissue repair therapy.

Injectable hyaluronic acid hydrogels encapsulating drug nanocrystals for long-term treatment of inflammatory arthritis.

Antiproliferative chemotherapeutic agents offer a potential effective treatment for inflammatory arthritis. However, their clinical application is limited by high systemic toxicity, low joint bioavailability as well as formulation challenges. Here, we report an intra‐articular drug delivery system combining hyaluronic acid hydrogels and drug nanocrystals to achieve localized and sustained delivery of an antiproliferative chemotherapeutic agent camptothecin for long‐term treatment of inflammatory arthritis. We synthesized a biocompatible, in situ‐forming injectable hyaluronic acid hydrogel using a naturally occurring click chemistry: cyanobenzothiazole/cysteine reaction, which is the last step reaction in synthesizing D‐luciferin in fireflies. This hydrogel was used to encapsulate camptothecin nanocrystals (size of 160–560 nm) which released free camptothecin in a sustained manner for 4 weeks. In vivo studies confirmed that the hydrogel remained in the joint over 4 weeks. By using the collagen‐induced arthritis rat model, we demonstrate that the hydrogel‐camptothecin formulation could alleviate arthritis severity as indicated by the joint size and interleukin‐1β level in the harvested joints, as well as from histological and microcomputed tomography evaluation of joints. The hydrogel‐nanocrystal formulation strategy described here offers a potential solution for intra‐articular therapy for inflammatory arthritis.

Comparative Physicochemical Analysis among 1,4-Butanediol Diglycidyl Ether Cross-Linked Hyaluronic Acid Dermal Fillers.

(1) Background: Injectable hyaluronic acid (HA) dermal fillers are used in several chirurgical practices and in aesthetic medicine. HA filler stability can be enhanced through different cross-linking technologies; one of the most frequently cross-linker used is 1,4-butanediol diglycidyl ether (BDDE), also present in the HA-BDDE dermal filler family of the company Matex Lab S.p.A. (Brindisi, Italy). Our overview is focused on their characterization, drawing a correlation between matrix structure, rheological and physicochemical properties related to their cross-linking technologies. (2) Methods: Four different injectable HA hydrogels were characterized through optical microscopic examination and rheological behavior investigation. (3) Results: The cross-linked HA dermal fillers showed a fibrous “spiderweb-like” matrix structure and an elastic and solid-like profile. (4) Conclusions: The comparative analysis represents a preliminary characterization of these injectable medical devices in order to identify their best field of application.

Subcutaneously Injectable Hyaluronic Acid Hydrogel for Sustained Release of Donepezil with Reduced Initial Burst Release: Effect of Hybridization of Microstructured Lipid Carriers and Albumin

The daily oral administration of acetylcholinesterase (AChE) inhibitors for Alzheimer’s disease features low patient compliance and can lead to low efficacy or high toxicity owing to irregular intake. Herein, we developed a subcutaneously injectable hyaluronic acid hydrogel (MLC/HSA hydrogel) hybridized with microstructured lipid carriers (MLCs) and human serum albumin (HSA) for the sustained release of donepezil (DNP) with reduced initial burst release. The lipid carrier was designed to have a microsized mean diameter (32.6 ± 12.8 µm) to be well-localized in the hydrogel. The hybridization of MLCs and HSA enhanced the structural integrity of the HA hydrogel, as demonstrated by the measurements of storage modulus (G′), loss modulus (G″), and viscosity. In the pharmacokinetic study, subcutaneous administration of MLC/HSA hydrogel in rats prolonged the release of DNP for up to seven days and reduced the initial plasma concentration, where the Cmax value was 0.3-fold lower than that of the control hydrogel without a significant change in the AUClast value. Histological analyses of the hydrogels supported their biocompatibility for subcutaneous injection. These results suggest that a new hybrid MLC/HSA hydrogel could be promising as a subcutaneously injectable controlled drug delivery system for the treatment of Alzheimer’s disease.

Toward Physicochemical and Rheological Characterization of Different Injectable Hyaluronic Acid Dermal Fillers Cross-Linked with Polyethylene Glycol Diglycidyl Ether.

(1) Background: Injectable hyaluronic acid (HA) dermal fillers are used to restore volume, hydration and skin tone in aesthetic medicine. HA fillers differ from each other due to their cross-linking technologies, with the aim to increase mechanical and biological activities. One of the most recent and promising cross-linkers is polyethylene glycol diglycidyl ether (PEGDE), used by the company Matex Lab S.p.A., (Brindisi, Italy) to create the HA dermal filler PEGDE family. Over the last few years, several studies have been performed to investigate the biocompatibility and biodegradability of these formulations, but little information is available regarding their matrix structure, rheological and physicochemical properties related to their cross-linking technologies, the HA content or the degree of cross-linking. (2) Methods: Seven different injectable HA hydrogels were subjected to optical microscopic examination, cohesivity evaluation and rheological characterization in order to investigate their behavior. (3) Results: The analyzed cross-linked dermal fillers showed a fibrous “spiderweb-like” matrix structure, with each medical device presenting different and peculiar rheological features. Except for HA non cross-linked hydrogel 18 mg/mL, all showed an elastic and cohesive profile. (4) Conclusions: The comparative analysis with other literature works makes a preliminary characterization of these injectable medical devices possible.

An Injectable Hyaluronic Acid Hydrogel Promotes Intervertebral Disc Repair in a Rabbit Model.

An in vivo model to study the effect of an injectable hyaluronic acid (HA) hydrogel following puncture-induced lumbar disc injury in rabbits. The aim of this study was to determine the efficacy of an injectable HA hydrogel to maintain disc height and tissue hydration, promote structural repair, and attenuate inflammation and innervation in the lumbar discs. Previously, we have demonstrated that HA hydrogel alleviated inflammation, innervation, and pain to promote disc repair. Nevertheless, the effect of an injectable HA hydrogel in the lumbar disc in a weight-bearing animal model was not performed. We have adopted a surgically puncture-induced disc injury at lumbar levels in a rabbit model. The discs were grouped into sham, puncture with water injection, and puncture with HA hydrogel injection. Postoperatively, we measured changes in disc height using x-ray. We used magnetic resonance imaging to assess disc degeneration on tissue hydration after euthanasia. Post-mortem, we determined histological changes, innervation (PGP9.5) and inflammation (interleukin [IL]-6, IL-1β, and tumor necrosis factor [TNF]-α) in the discs. We have demonstrated a significant reduction of disc height and T2/T1ρ mapping with histological evidence of degenerative discs, increase of innervation and inflammation in puncture-induced disc injury over time. In the HA hydrogel group, disc height was increased at weeks four and eight. A slight increase of T2 mapping, but significantly in T1ρ mapping, was observed in the HA hydrogel group at week 8. We observed homogenous NP distribution and organised AF lamellae at week eight and a slight reduced innervation score in the treatment group. HA hydrogel significantly downregulated IL-6 expression at day 1. This, however, was only slightly reduced for IL-1β and TNF-α. An injectable HA hydrogel had the protective effects in suppressing the loss of disc height, promoting tissue hydration for structural repair, and attenuating inflammation and innervation to prevent further disc degeneration.Level of Evidence: N/A.

Injectable Hyaluronic Acid Hydrogel for the Co-Delivery of Gemcitabine Nanoparticles and Cisplatin for Malignant Ascites Therapy.

Malignant ascites indicate the presence of malignant cells in the peritoneal cavity that lower patient survival and reduce quality of life. Current chemotherapy regimens suffer from the dilution of ascites and rapid metabolism limiting their therapeutic efficacy. The storage and sustained release of drugs at the tumor site represents a promising strategy to improve drug efficacy. The aim of this study was to develop injectable hyaluronic acid hydrogel containing polymeric gemcitabine nanoparticles and cisplatin for the local treatment of malignant ascites through a dual sustained drug release pattern. Cell uptake assays showed that the drug-loaded nanoparticles readily entered tumor cells. Apoptosis and cell cycle analysis showed that the hydrogel system could enhance tumor cell apoptosis and arrest more cells in the G1 phase. In vivo experiments indicated that mice treated with the drug-loaded hydrogels manifested the most significant efficacy in ascites volume, tumor nodules, body weight, abdominal circumference, and survival. The expression of Ki-67 and CD31 also significantly decreased compared with other groups, indicative of anti-tumor activity. In addition, intraperitoneal administration of the hydrogel system led to no significant damage to vital organs. These findings confirm the clinical potential of the drug-loaded hydrogel system for the treatment of malignant ascites.