Effect of combined treatment with methylprednisolone and Nogo-A monoclonal antibody after rat spinal cord injury

Inhibition of LINGO1 as a therapeutic target to promote axonal regeneration and repair for neurological disorders

The Central nervous system is blemished by the high incidence of neurodegenerative diseases, which is known to cause disfiguration of regeneration and repair of axonal growth. Recognition of proteins that act as agents of repressing such repair has become the norm to tackle these abominable conditions. One such protein is LINGO1 that act as a repressor for axonal growth. Being one of the critical causative agents of several neurodegenerative pathways. Consequently, its inhibition may tend to help the outcomes of regenerative technologies aiming to outweigh the symptoms of neurodegenerative diseases. For this objective, LINGO1 was targeted with pharmacophore analogs of Fasudil and Ibuprofen, as they are known to have a deterring effect against the concerned protein. 1-Tosyl-2-(chloromethyl)-2,3-dihydro-1H-indole was found showing the least binding score of - 6.8, with verified ADMET admissibility. The pharmacological activity of the said ligand was estimated with QSAR tool showing favourable electro-steric model. All this was finally collaborated with a molecular dynamics simulation study which exhibited a stable structure compatibility of the ligand with LINGO-1. Further, the efficacy of the compound can be evaluated through experimental studies for inferring its future potential and utilization as an effective means to tackle neuronal regeneration and remyleination.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03789-4.

Regulation of neuronal repair and regeneration through inhibition of oligodendrocyte myelin glycoprotein (OMgp)

The inability of neural cells to regenerate themselves after an injury represents the major difference between neural cells and other cells of the body. Various factors are responsible for this, as the expression of myelin-derived inhibitors of axonal outgrowth such as neurite outgrowth inhibitor (Nogo), myelin-associated growth factor, and oligodendrocyte-myelin glycoprotein (OMgp) hinder the central nervous system (CNS) axons to recover properly and inhibit the neuron regeneration. The patient with spinal cord injury can even permanently lose their function due to the inability of axons to regenerate. However, their role in neural regeneration in vivo is not known completely. During the study, we found that once CNS gets injured, the axon growth inhibitor OMgp binds to the Nogo-66 Receptor 1 (NgR1) which in turn restricts the normal functioning of CNS. Considering the OMgp as the target protein, two flavonoid libraries (curcumin and piperine) were screened against it to get potential inhibitors. The effectiveness of the ligands was first screened by three-tier structure-based virtual screening by Glide, Schrödinger. Based on the docking score, the best-docked compounds were taken for absorption, distribution, metabolism, and excretion analysis and the top two complexes from each library were chosen for simulation studies. Flavonoid ligands showed a much better binding affinity when compared with already known inhibitors Riluzole and Minocycline. To date, no natural inhibitors are known for OMgp. Hence, this study can provide novel insight for upcoming research in this area. Communicated by Ramaswamy H. Sarma.

Composite nanofibers incorporating alpha lipoic acid and atorvastatin provide neuroprotection after peripheral nerve injury in rats

Despite the new treatment strategies within the last 30 years, peripheral nerve injury (PNI) is still a worldwide clinical problem. The incidence rate of PNIs is 1 in 1000 individuals per year. In this study, we designed a composite nanoplatform for dual therapy in peripheral nerve injury and investigated the in-vivo efficacy in rat sciatic nerve crush injury model. Alpha-lipoic acid (ALA) was loaded into poly lactic-co-glycolic acid (PLGA) electrospun nanofibers which would release the drug in a faster manner and atorvastatin (ATR) loaded chitosan (CH) nanoparticles were embedded into PLGA nanofibers to provide sustained release. Sciatic nerve crush was generated via Yasargil aneurism clip with a holding force of 50 g/cm². Nanofiber formulations were administered to the injured nerve immediately after trauma. Functional recovery of operated rat hind limb was evaluated using the sciatic functional index (SFI), extensor postural thrust (EPT), withdrawal reflex latency (WRL) and Basso, Beattie, and Bresnahan (BBB) test up to one month in the post-operative period at different time intervals. In addition to functional recovery assessments, ultrastructural and biochemical analyses were carried out on regenerated nerve fibers. L-929 mouse fibroblast cell line and B35 neuroblastoma cell line were used to investigate the cytotoxicity of nanofibers before in-vivo experiments. The neuroprotection potential of these novel nanocomposite fiber formulations has been demonstrated after local implantation of composite nanofiber sheets incorporating ALA and ATR, which contributed to the recovery of the motor and sensory function and nerve regeneration in a rat sciatic nerve crush injury model.

The role of pharmacotherapy in modifying the neurological status of patients with spinal and spinal cord injuries

The aim here was to conduct a review of the literature on pharmacological therapies for modifying the neurological status of patients with spinal cord injuries. The PubMed database was searched for articles with the terms "spinal cord injury AND methylprednisolone/GM1/apoptosis inhibitor/calpain inhibitor/naloxone/tempol/tirilazad", in Portuguese or in English, published over the last five years. Older studies were included because of their historical importance. The pharmacological groups were divided according to their capacity to interfere with the physiopathological mechanisms of secondary injuries. Use of methylprednisolone needs to be carefully weighed up: other anti-inflammatory agents have shown benefits in humans or in animals. GM1 does not seem to have greater efficacy than methylprednisolone, but longer-term studies are needed. Many inhibitors of apoptosis have shown benefits in in vitro studies or in animals. Naloxone has not shown benefits. Tempol inhibits the main consequences of oxidation at the level of the spinal cord and other antioxidant drugs seem to have an effect superior to that of methylprednisolone. There is an urgent need to find new treatments that improve the neurological status of patients with spinal cord injuries. The benefits from treatment with methylprednisolone have been questioned, with concerns regarding its safety. Other drugs have been studied, and some of these may provide promising alternatives. Additional studies are needed in order to reach conclusions regarding the benefits of these agents in clinical practice.

Nogo-A expression dynamically varies after spinal cord injury

The mechanism involved in neural regeneration after spinal cord injury is unclear. The myelin-derived protein Nogo-A, which is specific to the central nervous system, has been identified to negatively affect the cytoskeleton and growth program of axotomized neurons. Studies have shown that Nogo-A exerts immediate and chronic inhibitory effects on neurite outgrowth. In vivo, inhibitors of Nogo-A have been shown to lead to a marked enhancement of regenerative axon extension. We established a spinal cord injury model in rats using a free-falling weight drop device to subsequently investigate Nogo-A expression. Nogo-A mRNA and protein expression and immunoreactivity were detected in spinal cord tissue using real-time quantitative PCR, immunohistochemistry and western blot analysis. At 24 hours after spinal cord injury, Nogo-A protein and mRNA expression was low in the injured group compared with control and sham-operated groups. The levels then continued to drop further and were at their lowest at 3 days, rapidly rose to a peak after 7 days, and then gradually declined again after 14 days. These changes were observed at both the mRNA and protein level. The transient decrease observed early after injury followed by high levels for a few days indicates Nogo-A expression is time dependent. This may contribute to the lack of regeneration in the central nervous system after spinal cord injury. The dynamic variation of Nogo-A should be taken into account in the treatment of spinal cord injury.

Beneficial effect of interleukin-1 receptor antagonist protein on spinal cord injury recovery in the rat

We assessed the effect of treatment with the interleukin-1 receptor antagonist protein (IRAP) on morphological and functional recovery in a rat model of SCI. All sections were processed for immunohistochemistry, hematoxylin-eosin, and Nissl staining. Rats were assessed for hind limb motor function using the Basso, Beattie, and Bresnahan (BBB) hind limb locomotor rating scale and the inclined plane test. At 1, 48, and 72 h after operation, there was a significant increase in neurofilament proteins and brain-derived neurotrophic factor expression in the IRAP group I when compared with the saline group I and the sham-operated group I (P < 0.05). The mean inclined plane scores and BBB scores for the IRAP group II were higher than the saline group II at 1, 2, 3, and 4 weeks post-injury (P < 0.05). In conclusion, treatment with IRAP enhanced neuronal survival after SCI.

In vitro sustained release of bioactive anti-NogoA, a molecule in clinical development for treatment of spinal cord injury

Anti-NogoA is a promising anti-inhibitory molecule that has been shown to enhance functional recovery after spinal cord injury when delivered in rat and primate models over the span of weeks. To achieve this sustained release, anti-NogoA is typically delivered by osmotic minipumps; however, external minipumps are susceptible to infection. To address this issue, we developed a drug delivery system that consists of anti-NogoA-loaded poly(lactic-co-glycolic acid) nanoparticles dispersed in a hydrogel of hyaluronan and methylcellulose (composite HAMC). To optimize in vitro release, we screened formulations for improved anti-NogoA bioactivity and sustained release based on combinations of co-encapsulated trehalose, hyaluronan, MgCO(3), and CaCO(3). Co-encapsulated MgCO(3) and CaCO(3) slowed the rate of anti-NogoA release and did not influence anti-NogoA bioactivity. Co-encapsulated trehalose significantly improved anti-NogoA bioactivity at early release time points by stabilizing the protein during lyophilization. Co-encapsulated trehalose with hyaluronan improved bioactivity up to 28d and dramatically increased the rate and duration of sustained delivery. The sustained release of bioactive anti-NogoA from composite HAMC is a compelling formulation for in vivo evaluation in a model of spinal cord injury.

Clinical and experimental advances in regeneration of spinal cord injury

Spinal cord injury (SCI) is one of the major disabilities dealt with in clinical rehabilitation settings and is multifactorial in that the patients suffer from motor and sensory impairments as well as many other complications throughout their lifetimes. Many clinical trials have been documented during the last two decades to restore damaged spinal cords. However, only a few pharmacological therapies used in clinical settings which still have only limited effects on the regeneration, recovery speed, or retraining of the spinal cord. In this paper, we will introduce recent clinical trials, which performed pharmacological treatments and cell transplantations for patients with SCI, and evaluate recent in vivo studies for the regeneration of injured spinal cord, including stem-cell transplantation, application of neurotrophic factors and suppressor of inhibiting factors, development of biomaterial scaffolds and delivery systems, rehabilitation, and the combinations of these therapies to evaluate what can be appropriately applied in the future to the patients with SCI.