Recovery from spinal cord injury using naturally occurring antiinflammatory compound curcumin: laboratory investigation

The potential of curcumin for treating spinal cord injury: a meta-analysis study

INTRODUCTION

In this paper, we conducted a meta-analysis on the curcumin effect on functional recovery provided by the Basso, Beattie, Brenham (BBB) test for rats, and the Basso mouse scale (BMS) for mice after spinal cord injury (SCI) in animal models.

METHOD

Data mining was performed, and the standard mean difference (SMD) between the treated and control (untreated) groups was calculated using the STATA software. Quality control and subgroup analysis were performed.

RESULTS

The analysis includes 24 experimental studies that showed curcumin had a strong significance in improving functional recovery after SCI (SMD = 3.38; 95% CI: 2.54-4.22; p < 0.001). When curcumin was administered daily, it had a stronger effect than single-dose treatment or weekly administration. Despite the same effect in the follow-up time before and after 4 weeks post-injury, but later 9 weeks, curcumin had only a moderate effect. Curcumin also significantly reduced the expression of GFAP (Glial fibrillary acidic protein) marker compared to untreated groups.

CONCLUSION

These findings suggest that daily administration of curcumin can be an effective approach to improving functional recovery after SCI.

The role of Wnt/mTOR signaling in spinal cord injury

Spinal cord injury (SCI) is the most common disabling spinal injury, a complex pathologic process that can eventually lead to severe neurological dysfunction. The Wnt/mTOR signaling pathway is a pervasive signaling cascade that regulates a wide range of physiological processes during embryonic development, from stem cell pluripotency to cell fate. Numerous studies have reported that Wnt/mTOR signaling pathway plays an important role in neural development, synaptogenesis, neuron growth, differentiation and survival after the central nervous system (CNS) is damaged. Wnt/mTOR also plays an important role in regulating various pathophysiological processes after spinal cord injury (SCI). After SCI, Wnt/mTOR signal regulates the physiological and pathological processes of neural stem cell proliferation and differentiation, neuronal axon regeneration, neuroinflammation and pain through multiple pathways. Due to the characteristics of the Wnt signal in SCI make it a potential therapeutic target of SCI. In this paper, the characteristics of Wnt/mTOR signal, the role of Wnt/mTOR pathway on SCI and related mechanisms are reviewed, and some unsolved problems are discussed. It is hoped to provide reference value for the research field of the role of Wnt/mTOR pathway in SCI, and provide a theoretical basis for biological therapy of SCI.

mTOR pathway: A potential therapeutic target for spinal cord injury

Spinal cord injury (SCI) is the most common disabling spinal injury, and the complex pathological process can eventually lead to severe neurological dysfunction. Many studies have reported that the mammalian target of rapamycin (mTOR) signaling pathway plays an important role in synaptogenesis, neuron growth, differentiation, and survival after central nervous system injury. It is also involved in various traumatic and central nervous system diseases, including traumatic brain injury, neonatal hypoxic-ischemic brain injury, Alzheimer's disease, Parkinson's disease, and cerebral apoplexy. mTOR has also been reported to play an important regulatory role in various pathophysiological processes following SCI. Activation of mTOR signals after SCI can regulate physiological and pathological processes, such as proliferation and differentiation of neural stem cells, regeneration of nerve axons, neuroinflammation, and glial scar formation, through various pathways. Inhibition of mTOR activity has been confirmed to promote repair in SCI. At present, many studies have reported that Chinese herbal medicine can inhibit the SCI-activated mTOR pathway to improve the microenvironment and promote nerve repair after SCI. Due to the role of the mTOR pathway in SCI, it may be a potential therapeutic target for SCI. This review is focused on the pathophysiological process of SCI, characteristics of the mTOR pathway, role of the mTOR pathway in SCI, role of inhibition of mTOR on SCI, and role and significance of inhibition of mTOR by related Chinese herbal medicine inhibitors in SCI. In addition, the review discusses the deficiencies and solutions to mTOR and SCI research shortcomings. This study hopes to provide reference for mTOR and SCI research and a theoretical basis for SCI biotherapy.

Nutritional interventions for spinal cord injury: preclinical efficacy and molecular mechanisms

Spinal cord injury (SCI) is a debilitating condition that leads to motor, sensory, and autonomic impairments. Its intrinsic pathophysiological complexity has hindered the establishment of effective treatments for decades. Nutritional interventions (NIs) for SCI have been proposed as a route to circumvent some of the problems associated with this condition. Results obtained in animal models point to a more holistic effect, rather than to specific modulation, of several relevant SCI pathophysiological processes. Indeed, published data have shown NI improves energetic imbalance, oxidative damage, and inflammation, which are promoters of improved proteostasis and neurotrophic signaling, leading ultimately to neuroprotection and neuroplasticity. This review focuses on the most well-documented Nis. The mechanistic implications and their translational potential for SCI are discussed.

Curcumin promotes functional recovery and inhibits neuronal apoptosis after spinal cord injury through the modulation of autophagy

Objective: The study was aimed to investigate whether the neuroprotective role of curcumin is associated with regulation of autophagy.Methods: Rat spinal cord injury (SCI) models were established according to Allen's weight-drop trauma method. Curcumin was administered 30 min after the contusion and continued weekly. At 3, 7, 14, 21, and 28 days after SCI, functional recovery was evaluated using the Basso, Beattie and Bresnahan (BBB) scoring and the oblique plate test, following which, spinal cord tissues were obtained. Histological changes and apoptosis were then measured with H&E staining and TUNEL assay. Glia activation, inflammatory infiltration, inflammatory factor release, and myelination were observed through immunohistochemical (IHC) staining and ELISA. Autophagy and Akt activation were detected by western blotting. After autophagy was inhibited by injection of chloroquine, TUNEL, inflammatory factor release, myelin basic protein (MBP) IHC staining and functional recovery evaluation were performed again.Results: Curcumin treatment promoted functional recovery after SCI and reduced neuron apoptosis, improved spinal cord integrity, recovery, and re-myelination, and suppressed the inflammatory response. Autophagy was enhanced and Akt/mTOR pathway was inhibited by curcumin. Autophagy inhibition partially eliminated the protective effect of curcumin on SCI.Conclusion: Curcumin may exert its therapeutic effect on SCI through the enhancement of autophagy, in which, inhibition of the Akt/mTOR signaling pathway may be also involved.

Euxanthone inhibits traumatic spinal cord injury via anti-oxidative stress and suppression of p38 and PI3K/Akt signaling pathway in a rat model

BACKGROUND

Owing to neurite promoting, antioxidant and anti-inflammatory effects of Euxanthone (Eux), the investigation was aimed to probe the neuroprotective efficacy of Eux against traumatic spinal cord injury (t-SCI) in rats and whether Eux can improve neuropathic function in t-SCI.

METHOD

Sprague-Dawley (SD) rats were randomized in - Sham, t-SCI, Eux30, and Eux60 (t-SCI + 30 and 60 mg/kg respectively). Animals with compression force-induced t-SCI were subjected to estimation of locomotor functions. Spinal cord water content and Evans blue (EB) effusion were determined for quantifying edema and intactness of the spinal cord. Oxidative stress and immunochemical markers were quantified by ELISA and western blotting.

RESULTS

Findings revealed that Eux60 group animals had greater Basso, Beattie, and Bresnahan (BBB) and (incline plane test) IPT score indicating improved locomotor functions. There was a reduction in the spinal edema and water content after Eux treatment, together with lowering of oxidative stress markers. The expression of IL-6, IL-12, IL-1β, caspase-3, RANKL, TLR4, NF-κB, p-38, PI3K, and Akt in spinal cord tissues of t-SCI-induced rats was lowered after Eux treatment.

CONCLUSION

Overall, the investigation advocates that Eux attenuates t-SCI and associated inflammation, oxidative damage, and resulting apoptosis via modulation of TLR4/NF-κB/p38 and PI3K/Akt signaling cascade.

Biochemistry, Safety, Pharmacological Activities, and Clinical Applications of Turmeric: A Mechanistic Review

Turmeric (Curcuma longa L.) is a popular natural drug, traditionally used for the treatment of a wide range of diseases. Its root, as its most popular part used for medicinal purposes, contains different types of phytochemicals and minerals. This review summarizes what is currently known on biochemistry, safety, pharmacological activities (mechanistically), and clinical applications of turmeric. In short, curcumin is considered as the fundamental constituent in ground turmeric rhizome. Turmeric possesses several biological activities including anti-inflammatory, antioxidant, anticancer, antimutagenic, antimicrobial, antiobesity, hypolipidemic, cardioprotective, and neuroprotective effects. These reported pharmacologic activities make turmeric an important option for further clinical research. Also, there is a discussion on its safety and toxicity.

Research progress in use of traditional Chinese medicine for treatment of spinal cord injury

BACKGROUND

Spinal cord injury (SCI) is a serious central nervous system disorder caused by trauma that has gradually become a major challenge in clinical medical research. As an important branch of worldwide medical research, traditional Chinese medicine (TCM) is rapidly moving towards a path of reform and innovation. Therefore, this paper systematically reviews research related to existing TCM treatments for SCI, with the aims of identifying deficits and shortcomings within the field, and proposing feasible alternative prospects.

METHODS

All data and conclusions in this paper were obtained from articles published by peers in relevant fields. PubMed, SciFinder, Google Scholar, Web of Science, and CNKI databases were searched for relevant articles. Results regarding TCM for SCI were identified and retrieved, then manually classified and selected for inclusion in this review.

RESULTS

The literature search identified a total of 652 articles regarding TCM for SCI. Twenty-eight treatments (16 active ingredients, nine herbs, and three compound prescriptions) were selected from these articles; the treatments have been used for the prevention and treatment of SCI. In general, these treatments involved antioxidative, anti-inflammatory, neuroprotective, and/or antiapoptotic effects of TCM compounds.

CONCLUSIONS

This paper showed that TCM treatments can serve as promising auxiliary therapies for functional recovery of patients with SCI. These findings will contribute to the development of diversified treatments for SCI.

Transplantation of activated olfactory ensheathing cells by curcumin strengthens regeneration and recovery of function after spinal cord injury in rats

BACKGROUND AIMS

The pro-regeneration capabilities of olfactory ensheathing cells (OECs) remain controversial. However, little is known regarding whether the transplantation of activated OECs by curcumin (CCM) elicits neural regeneration and functional recovery after spinal cord injury (SCI) in rats, and the possible molecular mechanisms have never been investigated.

METHODS

Primary OECs were treated with 1μM CCM for 1-3 days. Concomitantly, activated OECs were transplanted into the traumatic spinal cord of Sprague Dawley rats. One to 9 weeks after surgery, the assessment of behavior recovery was made using the Basso, Beattie and Bresnahan (BBB) locomotor scale; electrophysiology tests, such as somatosensory evoked potential (SEP) and motor evoked potential (MEP); and the cylinder test. Pathological study, including hematoxylin and eosin staining and immunofluorescence staining for neurofilaments (NFs), was conducted at 5 weeks post-surgery. In addition, activation profiles of OECs by CCM stimulus were assessed and levels of transglutaminase-2 (TG2) and phosphatidylserine receptor (PSR) in OECs stimulated by CCM were further determined.

RESULTS

CCM remarkably enhanced OEC proliferation, improved cell viability and strengthened secretion of neurotrophins and anti-inflammatory factors. In addition, the levels of TG2 and PSR in CCM-treated OECs were significantly elevated. More importantly, beyond 1 week post-transplantation of CCM-treated OECs into lesioned spinal cord, BBB score and cylinder test score were significantly higher than that seen in the other three groups and a more postponed latent SEP and MEP period was noted. Furthermore, 5 weeks later, numerous, well-arranged NF-positive nerve fibers, lesions with less cavities and reduced levels of pro-inflammatory cytokines were found in activated OEC implantation groups. In addition, the number of NF-positive fibers was significantly improved and the number and area of both cavities and gliotic scars were remarkably decreased compared with the corresponding controls.

CONCLUSIONS

Transplantation of OECs activated by CCM promotes neural regeneration and functional recovery following SCI, the underlying mechanisms of which are intimately associated with the elevated production of neurotrophic factors and anti-inflammatory factors in OECs stimulated by CCM as well as reduced pro-inflammatory cytokines from the post-contusion spinal cord. In addition, OECs activated by CCM were mediated through TG2 and PSR.

Spinal cord injury: pathophysiology, treatment strategies, associated challenges, and future implications

Axonal regeneration and formation of tripartite (axo-glial) junctions at damaged sites is a prerequisite for early repair of injured spinal cord. Transplantation of stem cells at such sites of damage which can generate both neuronal and glial population has gained impact in terms of recuperation upon infliction with spinal cord injury. In spite of the fact that a copious number of pre-clinical studies using different stem/progenitor cells have shown promising results at acute and subacute stages, at the chronic stages of injury their recovery rates have shown a drastic decline. Therefore, developing novel therapeutic strategies are the need of the hour in order to assuage secondary morbidity and effectuate improvement of the spinal cord injury (SCI)-afflicted patients' quality of life. The present review aims at providing an overview of the current treatment strategies and also gives an insight into the potential cell-based therapies for the treatment of SCI.

Spinal Cord Injuries in Dogs Part II: Standards of Care, Prognosis and New Perspectives

Severe spinal cord injuries (SCI), causing physical handicaps and accompanied by many serious complications, remains one of the most challenging problems in both, human and veterinary health care practices. The central nervous system in mammals does not regenerate, so the neurological deficits in a dog following SCI persists for the rest of its life and the affected animals display an image of permanent suffering. Diagnostics are based on: neurological examination, plain x-rays of vertebral column, x-rays of the vertebral column following intrathecal administration of a water-soluble contrast medium (myelography), x-rays of the vertebral column following epidural administration of a contrast medium (epidurography), computed tomography (CT) and/or magnetic resonance imaging (MRI). Currently, only limited therapeutic measures are available for the dogs with SCIs. They include: the administration of methylprednisolone sodium succinate (MPSS) during the acute stage; early spinal cord decompression; stabilisation of vertebral fractures or luxations; prevention and treatment of complications, and expert rehabilitation. Together with the progress in the understanding of pathophysiologic events occurring after SCI, different therapeutic strategies have been instituted, including the local delivery of MPSS, the utilisation of novel pharmacological agents, hypothermia, and stem/precursor cell transplantation have all been tested in the experimental models and preclinical trials with promising results. The aim of this review is the presentation of the generally accepted methods of diagnostics and management of dogs with SCIs, as well as to discuss new therapeutic modalities. The research strategy involved a PubMed, Medline (Ovid), Embase (Ovid) and ISI Web of Science literature search from January 2001 to December 2017 using the term “spinal cord injury”, in the English language literature; also references from selected papers were scanned and relevant articles included.

Does combined therapy of curcumin and epigallocatechin gallate have a synergistic neuroprotective effect against spinal cord injury?

Systematic inflammatory response after spinal cord injury (SCI) is one of the factors leading to lesion development and a profound degree of functional loss. Anti-inflammatory compounds, such as curcumin and epigallocatechin gallate (EGCG) are known for their neuroprotective effects. In this study, we investigated the effect of combined therapy of curcumin and EGCG in a rat model of acute SCI induced by balloon compression. Immediately after SCI, rats received curcumin, EGCG, curcumin + EGCG or saline [daily intraperitoneal doses (curcumin, 6 mg/kg; EGCG 17 mg/kg)] and weekly intramuscular doses (curcumin, 60 mg/kg; EGCG 17 mg/kg)] for 28 days. Rats were evaluated using behavioral tests (the Basso, Beattie, and Bresnahan (BBB) open-field locomotor test, flat beam test). Spinal cord tissue was analyzed using histological methods (Luxol Blue-cresyl violet staining) and immunohistochemistry (anti-glial fibrillary acidic protein, anti-growth associated protein 43). Cytokine levels (interleukin-1β, interleukin-4, interleukin-2, interleukin-6, macrophage inflammatory protein 1-alpha, and RANTES) were measured using Luminex assay. Quantitative polymerase chain reaction was performed to determine the relative expression of genes (Sort1, Fgf2, Irf5, Mrc1, Olig2, Casp3, Gap43, Gfap, Vegf, NfκB, Cntf) related to regenerative processes in injured spinal cord. We found that all treatments displayed significant behavioral recovery, with no obvious synergistic effect after combined therapy of curcumin and ECGC. Curcumin and EGCG alone or in combination increased axonal sprouting, decreased glial scar formation, and altered the levels of macrophage inflammatory protein 1-alpha, interleukin-1β, interleukin-4 and interleukin-6 cytokines. These results imply that although the expected synergistic response of this combined therapy was less obvious, aspects of tissue regeneration and immune responses in severe SCI were evident.

Neuroprotective effects of astaxanthin in a rat model of spinal cord injury

Spinal cord injury (SCI) often leads to constant neurological deficits and long-term unalterable disability. Apoptosis plays an important role in the initiation of the secondary injury cascades leading to progressive tissue damage and severely functional deficits after SCI. Although the primary mechanical destructive events cannot be reversed, a therapeutic intervention could be carried out in order to moderate the secondary injury damage several hours to weeks after injury. Astaxanthin (AST) is a strong antioxidant and anti-inflammatory agents with the potential to render anti-apoptotic and neuroprotective effects. In the current study, we examined the therapeutic potential of AST on adult rats after severe SCI contusion. Results of BBB scores showed that AST improved motor function after SCI compared to control groups. Western blot analysis showed reduced expression of Bax and Cleaved-caspase-3 proteins and increased expression of the Bcl-2 protein in response to AST treatment (p<0.05). The histology results also showed that AST considerably preserved myelinated white matter and the number of motor neurons. This study is the first to report that AST reduces neuronal apoptosis, diminishes pathological tissue damage and improves functional recovery after SCI. The observed prominent neuroprotective effects, introduces AST as a promising therapy for SCI.

The Potential of Curcumin in Treatment of Spinal Cord Injury

Current treatment for spinal cord injury (SCI) is supportive at best; despite great efforts, the lack of better treatment solutions looms large on neurological science and medicine. Curcumin, the active ingredient in turmeric, a spice known for its medicinal and anti-inflammatory properties, has been validated to harbor immense effects for a multitude of inflammatory-based diseases. However, to date there has not been a review on curcumin's effects on SCI. Herein, we systematically review all known data on this topic and juxtapose results of curcumin with standard therapies such as corticosteroids. Because all studies that compare the two show superior results for curcumin over corticosteroids, it could be true that curcumin better acts at the inflammatory source of SCI-mediated neurological injury, although this question remains unanswered in patients. Because curcumin has shown improvements from current standards of care in other diseases with few true treatment options (e.g., osteoarthritis), there is immense potential for this compound in treating SCI. We critically and systematically summarize available data, discuss clinical implications, and propose further testing of this well-tolerated compound in both the preclinical and the clinical realms. Analyzing preclinical data from a clinical perspective, we hope to create awareness of the incredible potential that curcumin shows for SCI in a patient population that direly needs improvements on current therapy.

The Anti-Inflammatory Compound Curcumin Enhances Locomotor and Sensory Recovery after Spinal Cord Injury in Rats by Immunomodulation

Well known for its anti-oxidative and anti-inflammation properties, curcumin is a polyphenol found in the rhizome of Curcuma longa. In this study, we evaluated the effects of curcumin on behavioral recovery, glial scar formation, tissue preservation, axonal sprouting, and inflammation after spinal cord injury (SCI) in male Wistar rats. The rats were randomized into two groups following a balloon compression injury at the level of T9–T10 of the spinal cord, namely vehicle- or curcumin-treated. Curcumin was applied locally on the surface of the injured spinal cord immediately following injury and then given intraperitoneally daily; the control rats were treated with vehicle in the same manner. Curcumin treatment improved behavioral recovery within the first week following SCI as evidenced by improved Basso, Beattie, and Bresnahan (BBB) test and plantar scores, representing locomotor and sensory performance, respectively. Furthermore, curcumin treatment decreased glial scar formation by decreasing the levels of MIP1α, IL-2, and RANTES production and by decreasing NF-κB activity. These results, therefore, demonstrate that curcumin has a profound anti-inflammatory therapeutic potential in the treatment of spinal cord injury, especially when given immediately after the injury.

Curcumin modulates TLR4/NF-κB inflammatory signaling pathway following traumatic spinal cord injury in rats

BACKGROUND

Curcumin, a polyphenolic compound extracted from the plant turmeric, has protective effects on spinal cord injury (SCI) through attenuation of inflammatory response. This study was designed to detect whether curcumin modulates toll-like receptor 4 (TLR4) and the nuclear factor-kappa B (NF-κB) inflammatory signaling pathway in the injured rat spinal cord following SCI.

METHODS

Adult male Sprague-Dawley rats were subjected to laminectomy at T8-T9 and compression with a vascular clip. There were three groups: (a) sham group; (b) SCI group; and (g) SCI + curcumin group. We measured TLR4 gene and protein expression by real-time polymerase chain reaction and western blot analysis; NF-κB activity by electrophoretic mobility shift assay, inflammatory cytokines tumor necrosis factor-α, interleukin-1β, and interleukin-6 levels by enzyme-linked immunosorbent assay, hindlimb locomotion function by Basso, Beattie, and Bresnahan rating, spinal cord edema by wet/dry weight method, and apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) analysis.

RESULTS

The results showed that SCI induced the up-regulation of TLR4, NF-κB, and inflammatory cytokines in the injured rat spinal cord. Treatment with curcumin following SCI markedly down-regulated the levels of these agents related to the TLR4/NF-κB inflammatory signaling pathway. Administration of curcumin also significantly ameliorated SCI induced hind limb locomotion deficits, spinal cord edema, and apoptosis.

CONCLUSIONS

Post-SCI curcumin administration attenuates the TLR4/NF-κB inflammatory signaling pathway in the injured spinal cord, and this may be a mechanism whereby curcumin improves the outcome following SCI.

Neurological recovery and antioxidant effects of curcumin for spinal cord injury in the rat: a network meta-analysis and systematic review

Spinal cord injury (SCI) is a devastating condition affecting young, healthy individuals worldwide. Existing agents have inadequate therapeutic efficacy, and some are associated with side effects. Our objective is to summarize and critically assess the neurological recovery and antioxidant effects of curcumin for treatment of SCI in rat models. PubMed, Embase, and Chinese databases were searched from their inception date to February 2014. Two reviewers independently selected animal studies that evaluated neurological recovery and antioxidant effects of curcumin, compared to placebo, in rats with SCI, extracted data, and assessed the methodological quality. A pair-wise analysis and a network meta-analysis were performed. Eight studies with adequate randomization were selected and included in the systematic review. Two studies had a higher methodological quality. Overall, curcumin appears to significantly improve neurological function, as assessed using the Basso, Beattie, Bresnahan (BBB) locomotor rating scale (four studies, n=132; pooled mean difference [MD]=3.09; 95% confidence interval [CI], 3.40-4.45; p=0.04), in a random-effects model and decrease malondialdehyde (MDA) using a fixed-effects model (four studies, n=56; pooled MD=-1.00; 95% CI=-1.59 to -0.42; p=0.00008). Effect size, assessed using the BBB scale, increased gradually with increasing curcumin dosage. The difference between low- and high-dose curcumin using the BBB scale was statistically significant. Neurological recovery and antioxidant effects of curcumin were observed in rats with SCI despite poor study methodological quality.

Natural polyphenols and spinal cord injury

Polyphenols have been shown to have some of the neuroprotective effects against neurodegenerative diseases. These effects are attributed to a variety of biological activities, including free radical scavenging/antioxidant and anti-inflammatory and anti-apoptotic activities. In this regard, many efforts have been made to study the effects of various well-known dietary polyphenols on spinal cord injury (SCI) and to explore the mechanisms behind the neuroprotective effects. The aim of this paper is to present the mechanisms of neuroprotection of natural polyphenols used in animal models of SCI.

Low-dose curcumin stimulates proliferation, migration and phagocytic activity of olfactory ensheathing cells

One of the promising strategies for neural repair therapies is the transplantation of olfactory ensheathing cells (OECs) which are the glial cells of the olfactory system. We evaluated the effects of curcumin on the behaviour of mouse OECs to determine if it could be of use to further enhance the therapeutic potential of OECs. Curcumin, a natural polyphenol compound found in the spice turmeric, is known for its anti-cancer properties at doses over 10 µM, and often at 50 µM, and it exerts its effects on cancer cells in part by activation of MAP kinases. In contrast, we found that low-dose curcumin (0.5 µM) applied to OECs strikingly modulated the dynamic morphology, increased the rate of migration by up to 4-fold, and promoted significant proliferation of the OECs. Most dramatically, low-dose curcumin stimulated a 10-fold increase in the phagocytic activity of OECs. All of these potently stimulated behavioural characteristics of OECs are favourable for neural repair therapies. Importantly, low-dose curcumin gave a transient activation of p38 kinases, which is in contrast to the high dose curcumin effects on cancer cells in which these MAP kinases tend to undergo prolonged activation. Low-dose curcumin mediated effects on OECs demonstrate cell-type specific stimulation of p38 and ERK kinases. These results constitute the first evidence that low-dose curcumin can modulate the behaviour of olfactory glia into a phenotype potentially more favourable for neural repair and thereby improve the therapeutic use of OECs for neural repair therapies.

Curcumin protects against ischemic spinal cord injury: The pathway effect

Inducible nitric oxide synthase and N-methyl-D-aspartate receptors have been shown to participate in nerve cell injury during spinal cord ischemia. This study observed a protective effect of curcumin on ischemic spinal cord injury. Models of spinal cord ischemia were established by ligating the lumbar artery from the left renal artery to the bifurcation of the abdominal aorta. At 24 hours after model establishment, the rats were intraperitoneally injected with curcumin. Reverse transcription-polymerase chain reaction and immunohistochemical results demonstrated that after spinal cord ischemia, inducible nitric oxide synthase and N-methyl-D-aspartate receptor mRNA and protein expression significantly increased. However, curcumin significantly decreased inducible nitric oxide synthase and N-methyl-D-aspartate receptor mRNA and protein expression in the ischemic spinal cord. Tarlov scale results showed that curcumin significantly improved motor function of the rat hind limb after spinal cord ischemia. The results demonstrate that curcumin exerts a neuroprotective fect against ischemic spinal cord injury by decreasing inducible nitric oxide synthase and N-methyl-D-aspartate receptor expression.

Stem cell therapy and curcumin synergistically enhance recovery from spinal cord injury

Acute traumatic spinal cord injury (SCI) is marked by the enhanced production of local cytokines and pro-inflammatory substances that induce gliosis and prevent reinnervation. The transplantation of stem cells is a promising treatment strategy for SCI. In order to facilitate functional recovery, we employed stem cell therapy alone or in combination with curcumin, a naturally-occurring anti-inflammatory component of turmeric (Curcuma longa), which potently inhibits NF-κB. Spinal cord contusion following laminectomy (T9–10) was performed using a weight drop apparatus (10 g over a 12.5 or 25 mm distance, representing moderate or severe SCI, respectively) in Sprague-Dawley rats. Neural stem cells (NSC) were isolated from subventricular zone (SVZ) and transplanted at the site of injury with or without curcumin treatment. Functional recovery was assessed by BBB score and body weight gain measured up to 6 weeks following SCI. At the conclusion of the study, the mass of soleus muscle was correlated with BBB score and body weight. Stem cell therapy improved recovery from moderate SCI, however, it had a limited effect on recovery after severe SCI. Curcumin stimulated NSC proliferation in vitro, and in combination with stem cell therapy, induced profound recovery from severe SCI as evidenced by improved functional locomotor recovery, increased body weight, and soleus muscle mass. These findings demonstrate that curcumin in conjunction with stem cell therapy synergistically improves recovery from severe SCI. Furthermore, our results indicate that the effect of curcumin extends beyond its known anti-inflammatory properties to the regulation of stem cell proliferation.