Zinc remodels mitochondrial network through SIRT3/Mfn2-dependent mitochondrial transfer in ameliorating spinal cord injury.

Spinal cord injury (SCI) is a traumatic neuropathic condition that results in motor, sensory and autonomic dysfunction. Mitochondrial dysfunction caused by primary trauma is one of the critical pathogenic mechanisms. Moderate levels of zinc have antioxidant effects, promote neurogenesis and immune responses. Zinc normalises mitochondrial morphology in neurons after SCI. However, how zinc protects mitochondria within neurons is unknown. In the study, we used transwell culture, Western blot, Quantitative Real-time Polymerase Chain Reaction (QRT-PCR), ATP content detection, reactive oxygen species (ROS) activity assay, flow cytometry and immunostaining to investigate the relationship between zinc-treated microglia and injured neurons through animal and cell experiments. We found that zinc promotes mitochondrial transfer from microglia to neurons after SCI through Sirtuin 3 (SIRT3) regulation of Mitofusin 2 protein (Mfn2). It can rescue mitochondria in damaged neurons and inhibit oxidative stress, increase ATP levels and promote neuronal survival. Therefore, it can improve the recovery of motor function in SCI mice. In conclusion, our work reveals a potential mechanism to describe the communication between microglia and neurons after SCI, which may provide a new idea for future therapeutic approaches to SCI.

Folic acid-functionalized chitosan nanoparticles with bioenzyme activity for the treatment of spinal cord injury.

Spinal cord injury (SCI) is a central system disease with a high rate of disability. Pathological changes such as ischemia and hypoxia of local tissues, oxidative stress and apoptosis could lead to limb pain, paralysis and even life-threatening. It was reported that catalase (CAT) was the main antioxidant in organisms, which could remove reactive oxygen species (ROS) and release oxygen (O2). However, the efficacy of the drug is largely limited due to its poor stability, low bioavailability and inability to cross the blood spinal cord barrier (BSCB). Therefore, in this study, we prepared folic acid-functionalized chitosan nanoparticles to deliver CAT (FA-CSNCAT) for solving this problem. In vivo small animal imaging results showed that FA-CSN could carry CAT across the BSCB and target to the inflammatory site. In addition, Immunofluorescence, ROS assay and JC-1 probe were used to detect the therapeutic effect of FA-CSNCAT in vitro and in vivo. The results showed that FA-CSNCAT could alleviate the hypoxic environment at the injured site and remove ROS, thereby inhibiting oxidative stress and protecting neurons, which may provide a new idea for clinical medication of SCI.

Ginsenoside Rb1 improves energy metabolism after spinal cord injury.

Mitochondrial damage caused by oxidative stress and energy deficiency induced by focal ischemia and hypoxia are important factors that aggravate diseases. Studies have shown that ginsenoside Rb1 has neurotrophic and neuroprotective effects. However, whether it influences energy metabolism after spinal cord injury remains unclear. In this study, we treated mouse and cell models of spinal cord injury with ginsenoside Rb1. We found that ginsenoside Rb1 remarkably inhibited neuronal oxidative stress, protected mitochondria, promoted neuronal metabolic reprogramming, increased glycolytic activity and ATP production, and promoted the survival of motor neurons in the anterior horn and the recovery of motor function in the hind limb. Because sirtuin 3 regulates glycolysis and oxidative stress, mouse and cell models of spinal cord injury were treated with the sirtuin 3 inhibitor 3-TYP. When Sirt3 expression was suppressed, we found that the therapeutic effects of ginsenoside Rb1 on spinal cord injury were remarkably inhibited. Therefore, ginsenoside Rb1 is considered a potential drug for the treatment of spinal cord injury, and its therapeutic effects are closely related to sirtuin 3.

Codelivery of minocycline hydrochloride and dextran sulfate via bionic liposomes for the treatment of spinal cord injury.

After primary injury to the spinal cord, a series of microenvironmental changes can lead to secondary injury. The use of nano-targeted drug delivery systems to improve the postinjury microenvironment, inhibit inflammation and reduce neuronal apoptosis can be of great help during spinal cord injury (SCI) recovery. In this study, we prepared primary macrophage membranes bionic modified nanoliposomes (MH-DS@M-Lips) loaded with minocycline hydrochloride (MH) and dextran sulfate (DS) to target their delivery to the site of injury to bind calcium ions in situ and form metal ion complexes. Complex formation reduced calcium ion concentrations and calcium-associated neuronal apoptosis, while MH was slowly released to produce better anti-inflammatory effects. The successful preparation of MH-DS@M-Lips was verified using transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM), western blotting and dynamic light scattering (DLS). The targeting capability of the MH-DS@M-Lips was demonstrated using a Transwell system and an in vivo imaging system. The therapeutic efficacy of MH-DS@M-Lips was examined in vitro and in vivo using flow cytometry, immunofluorescence, ELISA kits and western blotting. The results showed that SCI mice treated with MH-DS@M-Lips received high behavioral scores, which led to the conclusion that MH-DS@M-Lips have great potential for the treatment of SCI.

Chitosan-modified hollow manganese dioxide nanoparticles loaded with resveratrol for the treatment of spinal cord injury.

Spinal cord injury (SCI) is a serious central nervous system disease, and secondary injury, including oxidative stress, the inflammatory response and accompanying neuronal apoptosis, will aggravate the condition. Due to the existence of the blood-spinal cord barrier (BSCB), the existing drugs for SCI treatment are difficulty to reach the injury site and thus their efficacy is limited. In this study, we designed chitosan-modified hollow manganese dioxide nanoparticles (CM) for the delivery of resveratrol to help it pass through the BSCB. Resveratrol (Res), a poorly soluble drug, was adsorbed into CM with a particle size of approximately 130 nm via the adsorption method, and the drug loading reached 21.39 ± 2.53%. In vitro dissolution experiment, the Res release of the loaded sample (CMR) showed slowly release behavior and reached about 87% at 36 h. In vitro at the cellular level and in vivo at the animal level experiments demonstrated that CMR could alleviate significantly oxidative stress by reducing level of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), and increasing glutathione peroxidase (GSH) level. Additionally, immunofluorescence (iNOS, IL-1ß, and Cl caspase-3) and western blot (iNOS, cox-2, IL-1ß, IL-10, Cl caspase-3, bax, and bcl-2) were used to detect the expression of related factors, which verified that CMR could also reduce inflammation and neuronal apoptosis. These results indicated that CM, as a potential central nervous system drug delivery material, was suitable for SCI treatment.