In situ delivery of a curcumin-loaded dynamic hydrogel for the treatment of chronic peripheral neuropathy

Lactoferrin-modified organic-inorganic hybrid mesoporous silica for co-delivery of levodopa and curcumin in the synergistic treatment of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a chronic neurodegenerative disorder primarily characterized by oxidative stress and dopaminergic neuron damage. While levodopa remains the cornerstone of PD treatment, its efficacy is limited by poor bioavailability and neuroprotective effects. Curcumin, a potent antioxidant derived from turmeric, demonstrates neuroprotective promise but also suffers from low bioavailability, hindering its therapeutic application. The combined therapeutic use of levodopa and curcumin offers a potential synergistic approach, though its neuroprotection potential through brain-targeted delivery remains underexplored.

PURPOSE

To develop a lactoferrin-modified organic-inorganic hybrid mesoporous silica nanoparticle system (Lf-lip@LC-MSNs) for co-delivering levodopa and curcumin, aiming to enhance neuroprotective efficacy and achieve brain-targeted delivery in PD.

METHODS

Lf-lip@LC-MSNs were engineered to encapsulate levodopa within a curcumin-loaded lipid bilayer, modified with lactoferrin for optimized brain-targeted delivery. In vitro studies were conducted on rotenone-damaged neuronal models to evaluate oxidative stress, mitochondrial dysfunction, α-synuclein aggregation, and neuronal survival. In vivo experiments on MPTP-induced PD mouse models evaluated biodistribution, therapeutic efficacy, and safety in healthy mice, focusing on motor function recovery.

RESULTS

The combination of levodopa and curcumin significantly reduced oxidative stress and α-synuclein accumulation, enhancing neuronal survival compared to monotherapies. Lf-lip@LC-MSNs further amplified these effects, achieving superior brain-targeted delivery and improved motor function restoration with minimal systemic toxicity.

CONCLUSIONS

The combination of curcumin and levodopa provided synergistic neuroprotection in PD models. By employing a targeted delivery system, the Lf-lip@LC-MSNs not only facilitated efficient brain targeting but also potentiated therapeutic outcomes, providing a compelling strategy for treating PD and paving the way for advancements in managing other neurodegenerative diseases.

Multidimensional exploration of hydrogels as biological scaffolds for spinal cord regeneration: mechanisms and future perspectives

Spinal cord injury (SCI) is a severe condition that frequently leads to permanent disabilities and neurological dysfunction. Its progression is driven by a multifaceted pathophysiology, encompassing direct trauma, secondary injury cascades, and intricate cellular and molecular responses. While current therapies focus on alleviating symptoms and restoring functionality, achieving effective neural regeneration in the spinal cord continues to be a significant challenge. Hydrogels, recognized for their exceptional biocompatibility, conductivity, and injectability, have shown great potential as advanced scaffolds to support neuronal and axonal regeneration. Recently, these materials have attracted significant interest in the field of SCI rehabilitation research. This review concludes recent progress in hydrogel-based strategies for SCI rehabilitation, emphasizing their distinct properties, underlying mechanisms, and integration with bioactive molecules, stem cells, and complementary biomaterials. Hydrogels foster neuronal regeneration by providing a tailored microenvironment, while advanced features such as self-repair, electrical conductivity, and controlled drug release significantly enhance their therapeutic potential in experimental models. This review explores hydrogel technologies and their applications, underscoring their potential to address the challenges of SCI treatment and paving the way for future clinical implementation.

Double-Layer Microneedle Patch Loaded with HA-PBA-QCT for Management of Paclitaxel-Induced Peripheral Neuropathic Pain

Chemotherapy-induced neuropathic pain (CINP) is a common adverse effect of antineoplastic drugs, often leading to dose reduction, treatment delays, or cessation of chemotherapy. Chemotherapy agents, like paclitaxel (PTX), damage the somatosensory nervous system by inducing neuroinflammation and oxidative stress, resulting in the sensitization of sensory neurons. Quercetin (QCT), known for its anti-inflammatory, antioxidant, and neuroprotective properties, is investigated for various neurological disorders. This work creates phenylboronic acid-modified hyaluronic acid (HA-PBA) gels with incorporated QCT and fabricates a double-layer microneedle (MN) patch using an HA-PBA-QCT complex in the needles and HA/polyvinyl alcohol (PVA) as the substrate. The crosslinking between PVA and HA-PBA-QCT enables a controlled, sustained release of QCT upon application. This work applies these QCT-loaded microneedle (QMN) patches to the instep skin of PTX-treated mice, which exhibits mechanical allodynia and cold hyperalgesia. Biweekly applications of the QMN patches significantly reduce pain responses. This analgesic effect is associated with the modulation of satellite glial cell activity, decreased macrophage infiltration, and reduced TNF-α and IL-6 levels in dorsal root ganglia (DRGs). Additionally, the treatment improves cellular antioxidant capacity, indicated by upregulated Nrf2 and catalase in DRGs. Overall, these findings suggest that double-layer QMN patches offer long-term anti-inflammatory and antioxidant benefits, potentially alleviating CINP in patients.

Hydrogel-Based Innovations in Carpal Tunnel Syndrome: Bridging Pathophysiological Complexities and Translational Therapeutic Gaps

Carpal Tunnel Syndrome (CTS) is a prevalent neuropathic disorder caused by chronic compression of the median nerve, leading to sensory and motor impairments. Conventional treatments, such as corticosteroid injections, wrist splinting, and surgical decompression, often fail to provide adequate outcomes for chronic or recurrent cases, emphasizing the need for innovative therapies. Hydrogels, highly biocompatible three-dimensional biomaterials with customizable properties, hold significant potential for CTS management. Their ability to mimic the extracellular matrix facilitates localized drug delivery, anti-adhesion barrier formation, and tissue regeneration. Advances in hydrogel engineering have introduced stimuli-responsive systems tailored to the biomechanical environment of the carpal tunnel, enabling sustained therapeutic release and improved tissue integration. Despite these promising developments, hydrogel applications for CTS remain underexplored. Key challenges include the absence of CTS-specific preclinical models and the need for rigorous clinical validation. Addressing these gaps could unlock the full potential of hydrogel-based interventions, which offer minimally invasive, customizable solutions that could improve long-term outcomes and reduce recurrence rates. This review highlights hydrogels as a transformative approach to CTS therapy, advocating for continued research to address translational barriers. These innovations have the potential to redefine the treatment landscape, significantly enhancing patient care and quality of life.

Intranasal Delivery of Curcumin Nanoparticles Improves Neuroinflammation and Neurological Deficits in Mice with Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) represents one of the most severe subtypes of stroke. Due to the complexity of the brain injury mechanisms following ICH, there are currently no effective treatments to significantly improve patient functional outcomes. Curcumin, as a potential therapeutic agent for ICH, is limited by its poor water solubility and oral bioavailability. In this study, mPEG-PCL is used to encapsulate curcumin, forming curcumin nanoparticles, and utilized the intranasal administration route to directly deliver curcumin nanoparticles from the nasal cavity to the brain. By inhibiting pro-inflammatory neuroinflammation of microglia following ICH in mice, reprogramming pro-inflammatory microglia toward an anti-inflammatory function, and consequently reducing neuronal inflammatory death and hematoma volume, this approach improved blood-brain barrier damage in ICH mice and promoted the recovery of neurological function post-stroke. This study offers a promising therapeutic strategy for ICH to mediate neuroinflammatory microenvironments.

Facile Preparation of Multifunctional Hydrogels with Sustained Resveratrol Release Ability for Bone Tissue Regeneration

Injectable hydrogels show great promise for bone tissue engineering applications due to their high biocompatibility and drug delivery capabilities. The bone defects in osteoporosis are usually characterized by an oxidative and inflammatory microenvironment that impairs the regeneration capability of bone tissues. To attenuate the reactive oxygen species (ROS) and promote bone regeneration, an anti-oxidative hydrogel with osteogenic capacity was developed in this study. The poorly water soluble, natural antioxidant, resveratrol, was encapsulated in thiolated Pluronic F-127 micelles with over 50-times-enhanced solubility. The injectable hydrogel was facilely formed because of the new thioester bond between the free thiol group in modified F-127 and the arylate group in hyaluronic acid (HA)-acrylate. The resveratrol-loaded hydrogel showed good viscoelastic properties and in vitro stability and was cyto-compatible with bone-marrow-derived mesenchymal stem cells (BMSCs). The hydrogel allowed for a sustained release of resveratrol for at least two weeks and effectively enhanced the osteogenic differentiation of BMSCs by the up-regulation of osteogenic markers, including ALP, OCN, RUNX-2, and COL1. Moreover, the hydrogel exhibited anti-oxidative and anti-inflammatory abilities through the scavenging of intracellular ROS in RAW264.7 cells and inhibiting the gene expression and secretion of pro-inflammatory cytokines TNF-α and IL-1β under LPS exposure. In summary, the results suggest that our multifunctional hydrogel loaded with resveratrol bearing osteogenic, anti-oxidative, and anti-inflammatory actions is easily prepared and represents a promising resveratrol delivery platform for the repair of osteoporotic bone defects.

Differentiated mesenchymal stem cells-derived exosomes immobilized in decellularized sciatic nerve hydrogels for peripheral nerve repair

Peripheral nerve injury (PNI) and the limitations of current treatments often result in incomplete sensory and motor function recovery, which significantly impact the patient's quality of life. While exosomes (Exo) derived from stem cells and Schwann cells have shown promise on promoting PNI repair following systemic administration or intraneural injection, achieving effective local and sustained Exo delivery holds promise to treat local PNI and remains challenging. In this study, we developed Exo-loaded decellularized porcine nerve hydrogels (DNH) for PNI repair. We successfully isolated Exo from differentiated human adipose-derived mesenchymal stem cells (hADMSC) with a Schwann cell-like phenotype (denoted as dExo). These dExo were further combined with polyethylenimine (PEI), and DNH to create polyplex hydrogels (dExo-loaded pDNH). At a PEI content of 0.1%, pDNH showed cytocompatibility for hADMSCs and supported neurite outgrowth of dorsal root ganglions. The sustained release of dExos from dExo-loaded pDNH persisted for at least 21 days both in vitro and in vivo. When applied around injured nerves in a mouse sciatic nerve crush injury model, the dExo-loaded pDNH group significantly improved sensory and motor function recovery and enhanced remyelination compared to dExo and pDNH only groups, highlighting the synergistic regenerative effects. Interestingly, we observed a negative correlation between the number of colony-stimulating factor-1 receptor (CSF-1R) positive cells and the extent of PNI regeneration at the 21-day post-surgery stage. Subsequent in vitro experiments demonstrated the potential involvement of the CSF-1/CSF-1R axis in Schwann cells and macrophage interaction, with dExo effectively downregulating CSF-1/CSF-1R signaling.

Digital Light Processing 4D Printing of Poloxamer Micelles for Facile Fabrication of Multifunctional Biocompatible Hydrogels as Tailored Wearable Sensors

The lack of both digital light processing (DLP) compatible and biocompatible photopolymers, along with inappropriate material properties required for wearable sensor applications, substantially hinders the employment of DLP 3D printing in the fabrication of multifunctional hydrogels. Herein, we discovered and implemented a photoreactive poloxamer derivative, Pluronic F-127 diacrylate, which overcomes these limitations and is optimized to achieve DLP 3D printed micelle-based hydrogels with high structural complexity, resolution, and precision. In addition, the dehydrated hydrogels exhibit a shape-memory effect and are conformally attached to the geometry of the detection point after rehydration, which implies the 4D printing characteristic of the fabrication process and is beneficial for the storage and application of the device. The excellent cytocompatibility and in vivo biocompatibility further strengthen the potential application of the poloxamer micelle-based hydrogels as a platform for multifunctional wearable systems. After processing them with a lithium chloride (LiCl) solution, multifunctional conductive ionic hydrogels with antifreezing and antiswelling properties along with good transparency and water retention are easily prepared. As capacitive flexible sensors, the DLP 3D printed micelle-based hydrogel devices exhibit excellent sensitivity, cycling stability, and durability in detecting multimodal deformations. Moreover, the DLP 3D printed conductive hydrogels are successfully applied as real-time human motion and tactile sensors with satisfactory sensing performances even in a -20 °C low-temperature environment.

A Multifunctional, Tough, Stretchable, and Transparent Curcumin Hydrogel with Potent Antimicrobial, Antioxidative, Anti-inflammatory, and Angiogenesis Capabilities for Diabetic Wound Healing

The treatment of diabetic chronic wounds is still faced with great challenges, mainly due to wound infection, excessive inflammation, and peripheral vascular disease in the wound area. Therefore, it is of great importance to develop a novel multifunctional hydrogel with high efficiency to accelerate diabetic wound healing. Curcumin (Cur), a Chinese herbal, has shown great potential in enhancing the healing of diabetic chronic wounds because of its immunomodulatory and pro-angiogenic properties. However, its low aqueous solubility, poor bioavailability, and chemical instability have limited its clinical applications. To address these current bottlenecks, novel poly(vinyl alcohol) (PVA)-chitosan (CS)/sodium alginate (SA)-Cur (PCSA) hydrogels were prepared for the first time, and they demonstrated all of the above intriguing performances by the Michael addition reaction of CS and Cur. PCSA hydrogels show multiple dynamic bonds, which possess strong mechanical properties (tensile stress: ∼0.980 MPa; toughness: ∼258.45 kJ/m3; and compressive strength: ∼7.38 MPa at strain of 80%). These intriguing performances provided an optimal microenvironment for cell migration and proliferation and also promoted the growth of blood vessels, leading to early angiogenesis. Importantly, the experimental results demonstrated that PCSA hydrogels can effectively transform pro-inflammatory M1 macrophages into anti-inflammatory M2 macrophages without the need for additional ingredients in vitro. Benefiting from these characteristics, a full-thickness diabetic wound in a rat model demonstrated that PCSA hydrogels can effectively accelerate wound healing via ROS-scavenging, downregulation of IL-1β, and upregulation of CD31 expression, resulting in angiogenesis and collagen deposition. This strategy not only provides a simple and safe Cur-based hydrogel for diabetic wound healing but also highlights the significant potential for the development of high-performance biomaterials for promoting diabetic wound healing using traditional Chinese medicine.

Therapeutic potential of luteolin-loaded poly(lactic-co-glycolic acid)/modified magnesium hydroxide microsphere in functional thermosensitive hydrogel for treating neuropathic pain

Neuropathic pain (NP) is a debilitating condition stemming from damage to the somatosensory system frequently caused by nerve injuries or lesions. While existing treatments are widely employed, they often lead to side effects and lack specificity. This study aimed to alleviate NP by developing an innovative sustained-release thermosensitive hydrogel system. The system incorporates hyaluronic acid (HA)/Pluronic F127 injectable hydrogel and bupivacaine (Bup, B) in combination with poly(lactic-co-glycolic acid; PLGA)/modified magnesium hydroxide (MH)/luteolin (Lut; PML) microspheres (PML@B/Gel). The PML@B/Gel was designed for localized and prolonged co-delivery of Bup and Lut as an anesthetic and anti-inflammatory agent, respectively. Our studies demonstrated that PML@B/Gel had exceptional biocompatibility, anti-inflammatory, and antioxidant properties. In addition, it exhibited efficient pain relief in in vitro cellular assays. Moreover, this functional hydrogel showed substantial sustained drug release while diminishing microglial activation. Consequently, it effectively mitigated mechanical allodynia and thermal hyperalgesia in in vivo rat models of chronic constriction injury (CCI). Based on our research findings, PML@B/Gel emerges as a promising therapeutic approach for the protracted treatment of NP.