Cell-Mediated Dexamethasone Release from Semi-IPNs Stimulates Osteogenic Differentiation of Encapsulated Mesenchymal Stem Cells

Development of a dexamethasone-hyaluronic acid conjugate with selective targeting effect for acute lung injury therapy

Acute lung injury (ALI), a critical complication of COVID-19, is characterized by widespread inflammation and severe pulmonary damage, necessitating intensive care for those affected. Although glucocorticoids (GCs), such as dexamethasone (Dex), have been employed clinically to lower mortality, their nonspecific systemic distribution has led to significant side effects, limiting their use in ALI treatment. In this study, we explored the conjugation of Dex to hyaluronic acid (HA) to achieve targeted delivery to inflamed lung tissues. We achieved a conjugation efficiency exceeding 98 % using a cosolvent system, with subsequent ester bond cleavage releasing the active Dex, as verified by liquid chromatography. Biodistribution and cellular uptake studies indicated the potential of the HA conjugate for cluster of differentiation 44 (CD44)-mediated targeting and accumulation. In a lipopolysaccharide-induced ALI mouse model, intravenous (IV) HA-Dex administration showed superior anti-inflammatory effects compared to free Dex administration. Flow cytometry analysis suggested that the HA conjugate preferentially accumulated in lung macrophages, suggesting the possibility of reducing clinical Dex dosages through this targeted delivery approach.

PEG hydrogel containing dexamethasone-conjugated hyaluronic acid reduces secondary injury and improves motor function in a rat moderate TBI model

Traumatic brain injury (TBI) leads to long-term impairments in motor and cognitive function. TBI initiates a secondary injury cascade including a neuro-inflammatory response that is detrimental to tissue repair and limits recovery. Anti-inflammatory corticosteroids such as dexamethasone can reduce the deleterious effects of secondary injury; but challenges associated with dosing, administration route, and side effects have hindered their clinical application. Previously, we developed a hydrolytically degradable hydrogel (PEG-bis-AA/HA-DXM) composed of poly (ethylene) glycol-bis-(acryloyloxy acetate) (PEG-bis-AA) and dexamethasone-conjugated hyaluronic acid (HA-DXM) for local and sustained dexamethasone delivery. In this study, we evaluated the effect of locally applied PEG-bis-AA/HA-DXM hydrogel on secondary injury and motor function recovery after moderate controlled cortical impact (CCI) TBI. Hydrogel treatment significantly improved motor function evaluated by beam walk and rotarod tests compared to untreated rats over 7 days post-injury (DPI). We also observed that the hydrogel treatment reduced lesion volume, inflammatory response, astrogliosis, apoptosis, and increased neuronal survival compared to untreated rats at 7 DPI. These results suggest that PEG-bis-AA/HA-DXM hydrogels can mitigate secondary injury and promote motor functional recovery following moderate TBI.

Dexamethasone-Loaded Hydrogels Improve Motor and Cognitive Functions in a Rat Mild Traumatic Brain Injury Model

Functional recovery following traumatic brain injury (TBI) is limited due to progressive neuronal damage resulting from secondary injury-associated neuroinflammation. Steroidal anti-inflammatory drugs, such as dexamethasone (DX), can reduce neuroinflammation by activated microglia and infiltrated macrophages. In our previous work, we developed hydrolytically degradable poly(ethylene) glycol-bis-(acryloyloxy acetate) (PEG-bis-AA) hydrogels with dexamethasone (DX)-conjugated hyaluronic acid (HA-DXM) and demonstrated that dexamethasone-loaded hydrogels (PEG-bis-AA/HA-DXM) can reduce neuroinflammation, apoptosis, and lesion volume and improve neuronal cell survival and motor function recovery at seven days post-injury (DPI) in a rat mild-TBI model. In this study, we investigate the effects of the local application of PEG-bis-AA/HA-DXM hydrogels on motor function recovery at 7 DPI and cognitive functional recovery as well as secondary injury at 14 DPI in a rat mild-CCI TBI model. We observed that PEG-bis-AA/HA-DXM-treated animals exhibit significantly improved motor functions by the rotarod test and cognitive functions by the Morris water maze test compared to untreated TBI animals. We also observed that PEG-bis-AA/HA-DXM hydrogels reduce the inflammatory response, apoptosis, and lesion volume compared to untreated animals at 14 DPI. Therefore, PEG-bis-AA/HA-DXM hydrogels can be promising a therapeutic intervention for TBI treatment.

Interpenetrating polymer network hydrogels as bioactive scaffolds for tissue engineering

Tissue engineering, after decades of exciting progress and monumental breakthroughs, has yet to make a significant impact on patient health. It has become apparent that a dearth of biomaterial scaffolds that possess the material properties of human tissue while remaining bioactive and cytocompatible has been partly responsible for this lack of clinical translation. Herein, we propose the development of interpenetrating polymer network hydrogels as materials that can provide cells with an adhesive extracellular matrix-like 3D microenvironment while possessing the mechanical integrity to withstand physiological forces. These hydrogels can be synthesized from biologically-derived or synthetic polymers, the former polymer offering preservation of adhesion, degradability, and microstructure and the latter polymer offering tunability and superior mechanical properties. We review critical advances in the enhancement of mechanical strength, substrate-scale stiffness, electrical conductivity, and degradation in IPN hydrogels intended as bioactive scaffolds in the past five years. We also highlight the exciting incorporation of IPN hydrogels into state-of-the-art tissue engineering technologies, such as organ-on-a-chip and bioprinting platforms. These materials will be critical in the engineering of functional tissue for transplant, disease modeling, and drug screening.

Dexamethasone Conjugates: Synthetic Approaches and Medical Prospects

Dexamethasone (DEX) is the most commonly prescribed glucocorticoid (GC) and has a wide spectrum of pharmacological activity. However, steroid drugs like DEX can have severe side effects on non-target organs. One strategy to reduce these side effects is to develop targeted systems with the controlled release by conjugation to polymeric carriers. This review describes the methods available for the synthesis of DEX conjugates (carbodiimide chemistry, solid-phase synthesis, reversible addition fragmentation-chain transfer [RAFT] polymerization, click reactions, and 2-iminothiolane chemistry) and perspectives for their medical application as GC drug or gene delivery systems for anti-tumor therapy. Additionally, the review focuses on the development of DEX conjugates with different physical-chemical properties as successful delivery systems in the target organs such as eye, joint, kidney, and others. Finally, polymer conjugates with improved transfection activity in which DEX is used as a vector for gene delivery in the cell nucleus have been described.

Hydrogel-mediated local delivery of dexamethasone reduces neuroinflammation after traumatic brain injury

Excessive and prolonged neuroinflammation leads to neuronal cell death and limits functional recovery after traumatic brain injury (TBI). Dexamethasone (DX) is a steroidal anti-inflammatory agent that is known to attenuate early expression of pro-inflammatory cytokines associated with activated microglia/macrophages. In this study, we investigated the effect of dexamethasone-conjugated hyaluronic acid (HA-DXM) incorporated in a hydrolytically degradable, photo-cross-linkable PEG-bis-(acryloyloxy acetate) (PEG-bis-AA) hydrogel on the inflammatory response, apoptosis, and functional recovery in a controlled cortical impact (CCI) rat TBI model. In vitro, DX release from PEG-bis-AA/HA-DXM hydrogel was slow in PBS without enzymes, but significantly increased in the presence of hyauronidase/esterase enzymes. TBI was generated by a CCI device armed with a 3 mm tip (3.5 m/sec, depth: 2 mm) and treated immediately with PEG-bis-AA/HA-DXM hydrogel. PEG-bis-AA/HA hydrogel without DX was used for comparison and untreated TBI group was used as a control. Significant reductions in cavity size, inflammatory response, and apoptosis were observed in animals treated with PEG-bis-AA/HA-DXM compared to those receiving PEG-bis-AA/HA and untreated. Animals receiving the PEG-bis-AA/HA-DXM hydrogel also exhibited higher neuronal cell survival and improved motor functional recovery compared to the other two groups.

Effect of naproxen on proliferation and differentiation of primary cell cultures isolated from human cartilage tissue

Non-steroidal anti-inflammatory drugs (NSAIDs) that are applied through oral, injectable or topical routes have been widely used in painful and inflammatory musculoskeletal diseases. The current study aimed to determine whether naproxen, an aryl acetic acid derivative with analgesic and anti-inflammatory effects, has a toxic effect on human chondrocytes. Samples containing monolayer primary chondrocyte cultures were prepared following resection from osteochondral tissues obtained from patients with gonarthrosis. Cell viability, toxicity and proliferation and levels of stage-specific embryonic antigen-1, a precursor to human prechondrocytes, were evaluated spectrophotometrically. The results from the untreated control group were compared with those of the study groups, where naproxen was administered in varying doses (1-1,000 µM). Surface morphologies of the cells were compared using inverted light and environmental scanning electron microscopy. Treatment groups were compared by analysis of variance with Tukey's honest difference post hoc test. P<0.01 was considered to indicate a statistically significant difference. The research revealed significant changes to proliferation and differentiation of chondrocytes in all treatment groups (P<0.01). Naproxen was demonstrated to suppress chondrocyte proliferation and differentiation, which may be an important factor to consider when prescribing this medication to patients.

Osteogenesis evaluation of duck's feet-derived collagen/hydroxyapatite sponges immersed in dexamethasone

Background

The aim of this study was to investigate the osteogenesis effects of DC and DC/HAp sponge immersed in without and with dexamethasone.

Methods

The experimental groups in this study were DC and DC/HAp sponge immersed in without dexamethasone (Dex(−)DC and Dex(−)-DC/HAp group) and with dexamethasone (Dex(+)-DC and Dex(+)-DC/HAp group). We characterized DC and DC/HAp sponge using compressive strength, scanning electron microscopy (SEM). Also, osteogenic differentiation of BMSCs on sponge (Dex(−)DC, Dex(−)-DC/HAp, Dex(+)-DC and Dex(+)-DC/HAp group) was assessed by SEM, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide (MTT) assay, alkaline phosphatase (ALP) activity assay and reverse transcription-PCR (RT-PCR).

Results

In this study, we assessed osteogenic differentiation of BMSCs on Duck’s feet-derived collagen (DC)/HAp sponge immersed with dexamethasone Dex(+)-DC/HAp. These results showed that Dex(+)-DC/HAp group increased cell proliferation and osteogenic differentiation of BMSCs during 28 days.

Conclusion

From these results, Dex(+)-DC/HAp can be envisioned as a potential biomaterial for bone regeneration applications.

ECM–oligourethene–silica hydrogels as a local drug release system of dexamethasone for stimulating macrophages

The incorporation of silica particles inside of extracellular matrix hydrogels supports the loading and releasing of dexamethasone, a therapeutic for modulating macrophage.