Fabrication of a Polylactide-Glycolide/Poly-ε-Caprolactone/Dextran/Plastrum Testudinis Extract Composite Anti-Inflammation Nanofiber Membrane via Electrospinning for Annulus Fibrosus Regeneration.

Tissue engineering is a promising approach for the treatment of chronic lower back pain (LBP) caused by intervertebral disc degeneration (IDD) resulting from degeneration and inflammation of annulus fibrosus (AF) tissue. However, scaffold with an anti-inflammatory effect on AF cells has not been reported. In this study, we fabricated a polylactide-glycolide (PLGA)/poly-ε-caprolactone (PCL)Zdextran (DEX) composite membrane loaded with plastrum testudinis extract (PTE), a Traditional Chinese Medicine herbal extract, via electrospinning. The membranes were characterized by mechanical measurements and scanning electron microscopy (SEM). Using an in vitro inflammation model induced by interleukin (IL)-1ß, the cytocompatibility and anti-inflammatory effects of the composites were investigated by CCK-8 assay and flow cytometry. Potential regulatory mechanisms were examined by RT-qPCR and Western blotting. The results showed that the P10P8D2 (PLGA 10 g, PCL 8 g, DEX 2 g) composite nanofiber membrane exhibited the most uniform diameter distribution, best mechanical properties, a moderate degradation rate, and the best cytocompatibility characteristics. The optimal concentration of PTE was 120 µg/mL. Importantly, P10P8D2 combined with PTE exhibited anti-inflammatory and cell proliferation promotion effects. Moreover, the NF-κBB/NLRP3/IL-ß signaling pathway was inactivated. Our findings suggested that the nanofiber membrane composed of P10P8D2 and PTE has anti-inflammatory and pro-proliferation effects on AF cells. It may provide an effective strategy for AF tissue regeneration.

Pre-Injection of Small Interfering RNA (siRNA) Promotes c-Jun Gene Silencing and Decreases the Survival Rate of Axotomy-Injured Spinal Motoneurons in Adult Mice.

Brachial plexus injury is a common clinical peripheral nerve trauma. A series of genes in motoneurons were activated in the corresponding segments of the spinal cord after brachial plexus roots axotomy. The spatial and temporal expression of these genes directly affects the speed of motoneuron axon regeneration and precise target organ reinnervation. In a previous study, we observed the overexpression of c-Jun in motoneurons of the spinal cord ventral horn after brachial plexus injury in rats. However, the relevance of c-Jun expression with respect to the fate of axotomy-induced branchial plexus injury in adult mice remains unknown. In the present study, we explored the function of c-Jun in motoneuron recovery after axotomy. We pre-injected small interfering RNA (siRNA) to knockdown c-Jun expression in mice and examined the effects of the overexpression of c-Jun in motoneurons after the axotomy of the brachial plexus in vivo. Axotomy induced c-Jun overexpression in the ventral horn motoneurons of adult mice from 3 to 14 days after injury. In addition, the pre-injection of siRNA transiently inhibited c-Jun expression and decreased the survival rate of axotomy-injured motoneurons. These findings indicate that the axotomy-induced overexpression of c-Jun plays an important role in the survival of ventral horn motoneurons in adult mice. In addition, the pre-injection of c-Jun siRNA through the brachial plexus stem effectively adjusts c-Jun gene expression at the ipsilateral side.

MiR-137-3p rescue motoneuron death by targeting calpain-2.

Brachial plexus root avulsion (BPRA) is a type of injury that leads to motor function loss as a result of motoneurons (MNs) degeneration. Here we identified that the reduced expression of rat miR-137-3p in the ventral horn of spinal cord was associated with MNs death. However, the pathophysiological role of miR-137-3p in root avulsion remains poorly understood. We demonstrated that the calcium-activated neutral protease-2 (calpain-2) was a direct target gene of miR-137-3p with miR-137-3p binding to the 3'-untranslated region of calpain-2. Silencing of calpain-2 suppressed the expression of neuronal nitric oxide synthase (nNOS), a primary source of nitric oxide (NO). After avulsion 2 weeks, up-regulation of miR-137-3p in the spinal cord reduced calpain-2 levels and nNOS expression inside spinal MNs, resulting in an amelioration of the MNs death. These events provide new insight into the mechanism by which upregulation of miR-137-3p can impair MN survival in the BPRA.

Propofol Protects Against H2O2-Induced Oxidative Injury in Differentiated PC12 Cells via Inhibition of Ca(2+)-Dependent NADPH Oxidase.

Propofol (2,6-diisopropylphenol) is a widely used general anesthetic with anti-oxidant activities. This study aims to investigate protective capacity of propofol against hydrogen peroxide (H2O2)-induced oxidative injury in neural cells and whether the anti-oxidative effects of propofol occur through a mechanism involving the modulation of NADPH oxidase (NOX) in a manner of calcium-dependent. The rat differentiated PC12 cell was subjected to H2O2 exposure for 24 h to mimic a neuronal in vitro model of oxidative injury. Our data demonstrated that pretreatment of PC12 cells with propofol significantly reversed the H2O2-induced decrease in cell viability, prevented H2O2-induced morphological changes, and reduced the ratio of apoptotic cells. We further found that propofol attenuated the accumulation of malondialdehyde (biomarker of oxidative stress), counteracted the overexpression of NOX core subunit gp91(phox) (NOX2) as well as the NOX activity following H2O2 exposure in PC12 cells. In addition, blocking of L-type Ca(2+) channels with nimodipine reduced H2O2-induced overexpression of NOX2 and caspase-3 activation in PC12 cells. Moreover, NOX inhibitor apocynin alone or plus propofol neither induces a significant downregulation of NOX activity nor increases cell viability compared with propofol alone in the PC12 cells exposed to H2O2. These results demonstrate that the protective effects of propofol against oxidative injury in PC12 cells are mediated, at least in part, through inhibition of Ca(2+)-dependent NADPH oxidase.

Identification of the Avulsion-Injured Spinal Motoneurons.

In laboratory studies, counting the spinal motoneurons that survived axonal injury is a major method to estimate the severity and regenerative capacity of the injured motoneurons after the axonal injury and rehabilitation surgery. However, the typical motoneuron marker, the choline acetyltransferase (ChAT), could not be detected in the injured motoneurons within the first 3-4 weeks postinjury. It is necessary to explore the useful and reliable specific phenotypic markers to assess the fate of injured motoneurons in axonal injury. Here, we used the fluorogold to retrograde trace the injured motoneurons in the spinal cord and studied the expression patterns of the alpha-motoneuron marker, the neuronal nuclei DNA-binding protein (NeuN) and the peripheral nerve injury marker, the activating transcriptional factor (ATF-3), and the oxidative stress marker, the neuronal nitric oxide synthase (nNOS) within the first 4 weeks of the root avulsion of the right brachial plexus (BPRA) in the adult male Sprague-Dawley rats. Our results showed that ATF-3 was rapidly induced and sustained to express only in the nuclei of the fluorogold-labeled injured motoneurons but none in the unaffected motoneurons from the 24 h of the injury; meanwhile, the NeuN almost disappeared in the avulsion-affected motoneurons within the first 4 weeks. The nNOS was not detected in the motoneurons until the second week of the injury. On the basis of the present data, we suggest that ATF-3 labels avulsion-injured motoneurons while NeuN and nNOS are poor markers within the first 4 weeks of BPRA.

Evaluation of Avulsion-Induced Neuropathology in Rat Spinal Cords with 18F-FDG Micro-PET/CT.

Brachial plexus root avulsion (BPRA) leads to dramatic motoneuron death and glial reactions in the corresponding spinal segments at the late stage of injury. To protect spinal motoneurons, assessment of the affected spinal segments should be done at an earlier stage of the injury. In this study, we employed 18F-FDG small-animal PET/CT to assess the severity of BPRA-induced cervical spinal cord injuries. Adult Sprague-Dawley rats were randomly treated and divided into three groups: Av+NS (brachial plexus root avulsion (Av) treated with normal saline), Av+GM1 (treated with monosialoganglioside), and control. At time points of 3 day (d), 1 week (w), 2 w, 4 w and 8 w post-injury, 18F-FDG micro-PET/CT scans and neuropathology assessments of the injured spinal roots, as well as the spinal cord, were performed. The outcomes of the different treatments were compared. The results showed that BPRA induced local bleeding and typical Wallerian degeneration of the avulsed roots accompanied by 18F-FDG accumulations at the ipsilateral cervical intervertebral foramen. BPRA-induced astrocyte reactions and overexpression of neuronal nitric oxide synthase in the motoneurons correlated with higher 18F-FDG uptake in the ipsilateral cervical spinal cord during the first 2 w post-injury. The GM1 treatment reduced BPRA-induced astrocyte reactions and inhibited the de novo nNOS expressions in spinal motoneurons. The GM1 treatment also protected spinal motoneurons from avulsion within the first 4 w post-injury. The data from this study suggest that 18F-FDG PET/CT could be used to assess the severity of BPRA-induced primary and secondary injuries in the spinal cord. Furthermore, GM1 is an effective drug for reducing primary and secondary spinal cord injuries following BPRA.

Efficient labeling in vitro with non-ionic gadolinium magnetic resonance imaging contrast agent and fluorescent transfection agent in bone marrow stromal cells of neonatal rats.

Although studies have been undertaken on gadolinium labeling-based molecular imaging in magnetic resonance imaging (MRI), the use of non-ionic gadolinium in the tracking of stem cells remains uncommon. To investigate the efficiency in tracking of stem cells with non-ionic gadolinium as an MRI contrast agent, a rhodamine-conjugated fluorescent reagent was used to label bone marrow stromal cells (BMSCs) of neonatal rats in vitro, and MRI scanning was undertaken. The fluorescent-conjugated cell uptake reagents were able to deliver gadodiamide into BMSCs, and cell uptake was verified using flow cytometry. In addition, the labeled stem cells with paramagnetic contrast medium remained detectable by an MRI monitor for a minimum of 28 days. The present study suggested that this method can be applied efficiently and safely for the labeling and tracking of bone marrow stromal cells in neonatal rats.

Lithium enhances survival and regrowth of spinal motoneurons after ventral root avulsion.

BACKGROUND: During the clinical treatment of the brachial plexus root avulsion (BPRA), reimplantation surgery can not completely repair the motor function of the hand because the axonal growth velocity of the spinal motoneurons (MNs) is too slow to re-innervate the intrinsic hand muscles before muscle atrophy. Here, we investigated whether lithium can enhance the regenerative capacity of the spinal MNs in a rat model of BPRA. RESULTS: The avulsion and immediate reimplantation of the C7 and C8 ventral roots were performed and followed with daily intraperitoneal administration of a therapeutic concentrationof LiCl. After a 20 week long-term rehabilitation, the motor function recovery of the injured forepaw was studied by a grasping test. The survival and regeneration of MNs were checked by choline acetyltransferase (ChAT) immunofluorescence and by Fluoro-Gold (FG) retrograde labeling through the median and ulnar nerves of the ventral horn MNs. The number and diameter of the nerve fibers in the median nerve were assessed by toluidine blue staining. Our results showed that lithium plus reimplantation therapy resulted in a significantly higher grasping strength of the digits of the injured forepaw. Lithium plus reimplantation allowed 45.1% ± 8.11% of ChAT-positive MNs to survive the injury and increased the number and diameter of nerve fibers in the median nerve. The number of FG-labeled regenerative MNs was significantly elevated in all of the reimplantation animals. Our present data proved that lithium can enhance the regenerative capacity of spinal MNs. CONCLUSIONS: These results suggest that immediate administration of lithium could be used to assist reimplantation surgery in repairing BPRA injuries in clinical treatment.

Time-specific microRNA changes during spinal motoneuron degeneration in adult rats following unilateral brachial plexus root avulsion: ipsilateral vs. contralateral changes.

BACKGROUND: Spinal root avulsion induces multiple pathophysiological events consisting of altered levels of specific genes and proteins related to inflammation, apoptosis, and oxidative stress, which collectively result in the death of the affected motoneurons. Recent studies have demonstrated that the gene changes involved in spinal cord injury can be regulated by microRNAs, which are a class of short non-coding RNA molecules that repress target mRNAs post-transcriptionally. With consideration for the time course of the avulsion-induced gene expression patterns within dying motoneurons, we employed microarray analysis to determine whether and how microRNAs are involved in the changes of gene expression induced by pathophysiological events in spinal cord motoneurons. RESULTS: The expression of a total of 3,361 miRNAs in the spinal cord of adult rats was identified. Unilateral root-avulsion resulted in significant alterations in miRNA expression. In the ipsilateral half compared to the contralateral half of the spinal cord, on the 3rd day after the injury, 55 miRNAs were upregulated, and 24 were downregulated, and on the 14th day after the injury, 36 miRNAs were upregulated, and 23 were downregulated. The upregulation of miR-146b-5p and miR-31a-3p and the downregulation of miR-324-3p and miR-484 were observed. Eleven of the miRNAs, including miR-21-5p, demonstrated a sustained increase; however, only miR-466c-3p presented a sustained decrease 3 and 14 days after the injury. More interestingly, 4 of the miRNAs, including miR-18a, were upregulated on the 3rd day but were downregulated on the 14th day after injury.Some of these miRNAs target inflammatory-response genes in the early stage of injury, and others target neurotransmitter transport genes in the intermediate stages of injury. The altered miRNA expression pattern suggests that the MAPK and calcium signaling pathways are consistently involved in the injury response. CONCLUSIONS: This analysis may facilitate the understanding of the time-specific altered expression of a large set of microRNAs in the spinal cord after brachial root avulsion.