Uric acid released from poly(ε-caprolactone) fibers as a treatment platform for spinal cord injury

Neuroprotective Riluzole-Releasing Electrospun Implants for Spinal Cord Injury

Spinal cord injury (SCI) results in paralysis, driven partly by widespread glutamate-induced secondary excitotoxic neuronal cell death in and around the injury site. While there is no curative treatment, the standard of care often requires interventive decompression surgery and repair of the damaged dura mater close to the injury locus using dural substitutes. Such intervention provides an opportunity for early and local delivery of therapeutics directly to the injured cord via a drug-loaded synthetic dural substitute for localized pharmacological therapy. Riluzole, a glutamate-release inhibitor, has shown neuroprotective potential in patients with traumatic SCI, and therefore, this study aimed to develop an electrospun riluzole-loaded synthetic dural substitute patch suitable for the treatment of glutamate-induced injury in neurons. A glutamate-induced excitotoxicity was optimized in SH-SY5Y cells by exploring the effect of glutamate concentration and exposure duration. The most effective timing for administering riluzole was found to be at the onset of glutamate release as this helped to limit extended periods of glutamate-induced excitotoxic cell death. Riluzole-loaded patches were prepared by using blend electrospinning. Physicochemical characterization of the patches showed the successful encapsulation of riluzole within polycaprolactone fibers. A drug release study showed an initial burst release of riluzole within the first 24 h, followed by a sustained release of the drug over 52 days to up to approximately 400 μg released for the highest loading of riluzole within fiber patches. Finally, riluzole eluted from electrospun fibers remained pharmacologically active and was capable of counteracting glutamate-induced excitotoxicity in SH-SY5Y cells, suggesting the clinical potential of riluzole-loaded dural substitutes in counteracting the effects of secondary injury in the injured spinal cord.

Electrospun gelatin/hyaluronic acid nanofibers as a platform for uric acid delivery to neural tissue

Uric acid (UA) is an antioxidant that has been reported to be a neuroprotective compound for injuries and diseases, and specifically, diseases of the central nervous system. However, uric acid is highly insoluble in aqueous solutions, and high levels in the serum lead to gout, which limits its use in humans. Here, we develop a novel drug delivery platform that will release uric acid in a sustained manner for application to neural tissue. We demonstrate that one-step incorporation of UA into an electrospun gelatin/hyaluronic acid nanofiber mat results in controlled release of UA in culture medium. Taking a unique approach, we made solutions of 12% gelatin and 1% hyaluronic acid in a formic acid solvent and added UA for production of nanofiber mats. We then dehydrothermally crosslinked the mats and tested for release of UA into physiological cell culture medium. To test whether the mats have any detrimental effects on healthy nervous system tissue, we cultured spinal cord explants on the mats extended and assessed extensions from the explants. We observed that comparable numbers and lengths of dendrites are extended from the spinal cord tissue, regardless of the amount UA content in the mats. Our results suggest that electrospun gelatin/hyaluronic acid nanofibers can be used as a platform for sustained uric acid delivery to neural tissue without detrimental effects.

Electrospun drug-loaded scaffolds for nervous system repair

Nervous system injuries, encompassing peripheral nerve injury (PNI), spinal cord injury (SCI), and traumatic brain injury (TBI), present significant challenges to patients' wellbeing. Traditional treatment approaches have limitations in addressing the complexity of neural tissue regeneration and require innovative solutions. Among emerging strategies, implantable materials, particularly electrospun drug-loaded scaffolds, have gained attention for their potential to simultaneously provide structural support and controlled release of therapeutic agents. This review provides a thorough exploration of recent developments in the design and application of electrospun drug-loaded scaffolds for nervous system repair. The electrospinning process offers precise control over scaffold characteristics, including mechanical properties, biocompatibility, and topography, crucial for creating a conducive environment for neural tissue regeneration. The large surface area of the resulting fibrous networks enhances biomolecule attachment, influencing cellular behaviors such as adhesion, proliferation, and migration. Polymeric electrospun materials demonstrate versatility in accommodating a spectrum of therapeutics, from small molecules to proteins. This enables tailored interventions to accelerate neuroregeneration and mitigate inflammation at the injury site. A critical aspect of this review is the examination of the interplay between structural properties and pharmacological effects, emphasizing the importance of optimizing both aspects for enhanced therapeutic outcomes. Drawing upon the latest advancements in the field, we discuss the promising outcomes of preclinical studies using electrospun drug-loaded scaffolds for nervous system repair, as well as future perspectives and considerations for their design and implementation. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Cypin Inhibition as a Therapeutic Approach to Treat Spinal Cord Injury-Induced Mechanical Pain

Cypin (cytosolic postsynaptic density protein 95 interactor) is the primary guanine deaminase in the central nervous system (CNS), promoting the metabolism of guanine to xanthine, an important reaction in the purine salvage pathway. Activation of the purine salvage pathway leads to the production of uric acid (UA). UA has paradoxical effects, specifically in the context of CNS injury as it confers neuroprotection, but it also promotes pain. Since neuropathic pain is a comorbidity associated with spinal cord injury (SCI), we postulated that small molecule cypin inhibitor B9 treatment could attenuate SCI-induced neuropathic pain, potentially by interfering with UA production. However, we also considered that this treatment could hinder the neuroprotective effects of UA and, in doing so, exacerbate SCI outcomes. To address our hypothesis, we induced a moderate midthoracic contusion SCI in female mice and assessed whether transient intrathecal administration of B9, starting at 1 d postinjury (dpi) until 7 dpi, attenuates mechanical pain in hindlimbs at 3 weeks pi. We also evaluated the effects of B9 on the spontaneous recovery of locomotor function. We found that B9 alleviates mechanical pain but does not affect locomotor function. Importantly, B9 does not exacerbate lesion volume at the epicenter. In accordance with these findings, B9 does not aggravate glutamate-induced excitotoxic death of SC neurons in vitro. Moreover, SCI-induced increased astrocyte reactivity at the glial scar is not altered by B9 treatment. Our data suggest that B9 treatment reduces mechanical pain without exerting major detrimental effects following SCI.

Hormetic Effects of Bioactive Compounds from Foods, Beverages, and Food Dressing: The Potential Role in Spinal Cord Injury

Spinal cord injury (SCI) is a damage or trauma to the spinal cord resulting in a total or partial loss of motor and sensory function. SCI is characterized by a disequilibrium between the production of reactive oxygen species and the levels of antioxidant defences, causing oxidative stress and neuroinflammation. This review is aimed at highlighting the hormetic effects of some compounds from foods, beverages, and food dressing that are able to reduce oxidative stress in patients with SCI. Although curcumin, ginseng, and green tea have been proposed for SCI management, low levels of antioxidant vitamins have been reported in individuals with SCI. Mediterranean diet includes food rich in vitamins and antioxidants. Moreover, food dressing, including spices, herbs, and extra virgin olive oil (EVOO), contains multiple components with hormetic effects. The latter involves the activation of the nuclear factor erythroid-derived 2, consequently increasing the antioxidant enzymes and decreasing inflammation. Furthermore, EVOO improves the bioavailability of carotenoids and could be a delivery system for bioactive compounds. In conclusion, Mediterranean dressing in addition to plant foods can have an important effect on redox balance in individuals with SCI.