Upregulation of glycosaminoglycan synthesis by Neurotropin in nucleus pulposus cells via stimulation of chondroitin sulfate N-acetylgalactosaminyltransferase 1: A new approach to attenuation of intervertebral disc degeneration

Minimally Invasive Intradiscal Delivery of BM-MSCs via Fibrous Microscaffold Carriers

Current treatments of degenerated intervertebral discs often provide only temporary relief or address specific causes, necessitating the exploration of alternative therapies. Cell-based regenerative approaches showed promise in many clinical trials, but limitations such as cell death during injection and a harsh disk environment hinder their effectiveness. Injectable microscaffolds offer a solution by providing a supportive microenvironment for cell delivery and enhancing bioactivity. This study evaluated the safety and feasibility of electrospun nanofibrous microscaffolds modified with chitosan (CH) and chondroitin sulfate (CS) for treating degenerated NP tissue in a large animal model. The microscaffolds facilitated cell attachment and acted as an effective delivery system, preventing cell leakage under a high disc pressure. Combining microscaffolds with bone marrow-derived mesenchymal stromal cells demonstrated no cytotoxic effects and proliferation over the entire microscaffolds. The administration of cells attached to microscaffolds into the NP positively influenced the regeneration process of the intervertebral disc. Injectable poly(l-lactide-co-glycolide) and poly(l-lactide) microscaffolds enriched with CH or CS, having a fibrous structure, showed the potential to promote intervertebral disc regeneration. These features collectively address critical challenges in the fields of tissue engineering and regenerative medicine, particularly in the context of intervertebral disc degeneration.

Arginine Biosynthesis Pathway Found to Play a Key Role in the Neuroprotective Effect of Liu-Wei-Luo-Bi (LWLB) Granules in Diabetic db/db Mice with Peripheral Neuropathy Using an Untargeted Metabolomics Strategy

Aim

Liu-Wei-Luo-Bi (LWLB) granules was a Chinese compound prescription for treating diabetic peripheral neuropathy (DPN). The aim of this study was to investigate the effect of LWLB granules on diabetic mice with peripheral neuropathy and to elucidate the potential mechanism based on an untargeted metabolomics approach.

Methods

One hundred forty db/db mice were randomly divided into seven groups: the Control group, DPN group, Mudan (MD) granules group, Epalrestat (Epa) group, and the LWLB low, medium, or high dose (LW-l, LW-m, or LW-h) group. After 12 weeks of treatment, body weight, blood glucose, mechanical pain threshold, motor conduction velocity (MCV), sensory conduction velocity (SCV), and Pathological Organization of the Sciatic and Caudal Nerves in mice were measured. Serum samples were collected for untargeted metabolomics analysis using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) and multivariate statistics. Disease-related pathways were screened out with function enrichment analyses of candidate biomarkers.

Results

LWLB granules can improve the peripheral neuropathy of type 2 diabetic mice with peripheral nerve conduction disorders, mainly through significantly improving the nerve conduction velocity (P < 0.05) and lowering the mechanical pain threshold (P < 0.05). A total of 43 metabolites were identified as potential biomarkers related to the therapeutic effect of LWLB granules. Fifty, 4, and 26; 23, 4, and 22; and 24, 1, and 16 biomarkers were discovered in the LW-l, LW-m, and LW-h groups at the 4th, 6th, and 12th weeks, respectively. Five, three, seven, five, and four metabolic pathways were found in MD, Epa, LW-l, LW-m, and LW-h groups, respectively. The arginine biosynthesis pathway is the overlapping pathway in LW-l, LW-m, and LW-h groups.

Conclusion

LWLB granules have an obvious neuroprotective effect on diabetic peripheral neuropathy, and the metabolism mechanism of LWLB is mainly related to the arginine biosynthesis pathway on diabetic db/db mice with peripheral neuropathy.

Two- and three-dimensional in vitro nucleus pulposus cultures: An in silico analysis of local nutrient microenvironments

Background

It is well established that the unique biochemical microenvironment of the intervertebral disc plays a predominant role in cell viability and biosynthesis. However, unless the effect of microenvironmental conditions is primary to a study objective, in vitro culture parameters that are critical for reproducibility are both varied and not routinely reported.

Aims

This work aims to investigate the local microenvironments of commonly used culture configurations, highlighting physiological relevance, potential discrepancies, and elucidating possible heterogeneity across the research field.

Materials and Methods

This work uses nutrient-transport in silico models to reflect on the effect of often underappreciated parameters, such as culture geometry and diffusional distance (vessel, media volume, construct size), seeding density, and external boundary conditions on the local microenvironment of two-dimensional (2D) and three-dimensional (3D) in vitro culture systems.

Results

We elucidate important discrepancies between the external boundary conditions such as the incubator level or media concentrations and the actual local cellular concentrations. Oxygen concentration and cell seeding density were found to be highly influential parameters and require utmost consideration when utilizing 3D culture systems.

Discussion

This work highlights that large variations in the local nutrient microenvironment can easily be established without consideration of several key parameters. Without careful deliberation of the microenvironment within each specific and unique system, there is the potential to confound in vitro results leading to heterogeneous results across the research field in terms of biosynthesis and matrix composition.

Conclusion

Overall, this calls for a greater appreciation of key parameters when designing in vitro experiments. Better harmony and standardization of physiologically relevant local microenvironments are needed to push toward reproducibility and successful translation of findings across the research field.

Jinmaitong ameliorates diabetic peripheral neuropathy in streptozotocin-induced diabetic rats by modulating gut microbiota and neuregulin 1

Jinmaitong (JMT), a compound prescription of traditional Chinese medicine, has long been used as a therapy for diabetic peripheral neuropathy (DPN). However, the neuroprotective mechanisms of JMT and its effect on gut microbiota remained unknown. Here, we examined the effects of JMT on behavior, pathomorphology and gut microbiota in streptozotocin (STZ)-induced DPN rats. Compared to distilled water administration, JMT reversed decreases in mechanical withdraw threshold and intraepidermal nerve fiber density, improved neurological morphology of sciatic nerves, increased serum neuregulin 1 (NRG1) level and contactin-associated protein (Caspr)-positive paranodes, and decreased amyloid precursor protein (APP) accumulation in DPN rats. More importantly, JMT enriched nine species of the gut microbiota of DPN rats, helping to prevent dysbiosis. Among these species, p_Actinobacteria, p_Proteobacteria and c_Actinobacteria were negatively correlated with DPN phenotypes and positively correlated with serum NRG1 level. These results indicate that JMT may exert a neuroprotective effect by modulating phenotype-associated gut microbiota and increasing serum NRG1 level in STZ-induced DPN rats. JMT may therefore be an effective complementary and alternative anti-DPN therapy.

Age-dependent microstructural changes of the intervertebral disc: a validation of proteoglycan-sensitive spectral CT

Objective

To analyze the two major components of the intervertebral disc (IVD) in an ex vivo phantom, as well as age-related changes in patients.

Methods

Collagen and chondroitin sulfate were imaged at different concentrations in agar solution. Age-related changes in disc density were retrospectively analyzed in normal-appearing discs in dual-energy computed tomography (DECT) images from a patient cohort with various spinal pathologies (n = 136). All computed tomography (CT) scans were acquired using single-source DECT at 80 and 135 kVp with automatic exposure calculation. In 136 patients, the attenuation of normal-appearing discs on collagen/chondroitin maps (cMaps) correlated with the patients’ age with Pearson’s r using standardized regions of interest in the anterior anulus fibrosus (AAF) and nucleus pulposus (NP).

Results

DECT collagen mapping revealed concentration-dependent Hounsfield units (HU) of IVD components. For collagen, we found Pearson’s r = 0.9610 (95% CI 0.6789–0.9959), p = 0.0023 at 120 kVe, and r = 0.8824 (95% CI 0.2495–0.9871), p = 0.0199 in cMap. For chondroitin sulfate, Pearson’s r was 0.9583 (95% CI 0.6603–0.9956), p = 0.0026 at 120 kVp, and r = 0.9646 (95% CI 0.7044–0.9963), p = 0.0019 in cMap. Analysis of normal-appearing IVDs revealed an inverse correlation of density with age in the AAF: Pearson’s r = − 0.2294 at 135 kVp (95% CI − 0.4012 to − 0.04203; p=0.0141) and r = − 0.09341 in cMap (95% CI − 0.2777 to 0.09754; p = 0.0003). In the NP, age and density did not correlate significantly at 135 kVp (p = 0.9228) and in cMap (p = 0.3229).

Conclusions

DECT-based collagen mapping allows microstructural analysis of the two main intervertebral disc components—collagen and chondroitin sulfate. IVD density declines with age, presumably due to a reduction in collagen and chondroitin sulfate content. Age-related alterations of disc microstructure appear most pronounced in the AAF.

Key Points

• DECT-based collagen mapping allows precise analysis of the two main intervertebral disc components—collagen and chondroitin sulfate.

• Intervertebral disc (IVD) density declines with age, presumably due to a reduction in collagen and chondroitin sulfate content.

• Age-related alterations of disc microstructure are most pronounced in the anterior anulus fibrosus (AAF).

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08028-z.

Protracted hypomobility in the absence of trigeminal sensitization after cortical spreading depolarization: Relevance to migraine postdrome

Migraine sufferers often exhibit photophobia and physical hypoactivity in the postdrome and interictal periods, for which no effective therapy currently exists. Cortical spreading depolarization (CSD) is a neural phenomenon underlying migraine aura. We previously reported that CSD induced trigeminal sensitization, photophobia, and hypomobility at 24 h in mice. Here, we examined the effects of CSD induction on light sensitivity and physical activity in mice at 48 h and 72 h. Trigeminal sensitization was absent at both time points. CSD-subjected mice exhibited significantly less ambulatory time in both light (P = 0.0074, the Bonferroni test) and dark (P = 0.0354, the Bonferroni test) zones than sham-operated mice at 72 h. CSD-subjected mice also exhibited a significantly shorter ambulatory distance in the light zone at 72 h than sham-operated mice (P = 0.0151, the Bonferroni test). Neurotropin® is used for the management of chronic pain disorders, mainly in Asian countries. The CSD-induced reductions in ambulatory time and distance in the light zone at 72 h were reversed by Neurotropin® at 0.27 NU/kg. Our experimental model seems to recapitulate migraine-associated clinical features observed in the postdrome and interictal periods. Moreover, Neurotropin® may be effective in ameliorating postdromal/interictal hypoactivity, especially in a light environment.

Association of NAT2 genetic polymorphism with the efficacy of Neurotropin® for the enhancement of aggrecan gene expression in nucleus pulposus cells: a pilot study

BACKGROUND

Intervertebral disc degeneration, one of the major causes of low-back pain, results from altered biosynthesis/turnover of extracellular matrix in the disc. Previously, we reported that the analgesic drug Neurotropin® (NTP) had an anabolic effect on glycosaminoglycan synthesis in cultured nucleus pulposus (NP) cells via the stimulation of chondroitin sulfate N-acetylgalactosaminyltransferase 1. However, its effect on the aggrecan core protein was not significantly detected, because of the data variance. A microarray analysis suggested that the effect of NTP on aggrecan was correlated with N-acetyltransferase 2 (NAT2), a drug-metabolizing enzyme. Specific NAT2 alleles are known to correlate with rapid, intermediate, and slow acetylation activities and side effects of various drugs. We investigated the association between the efficacy of NTP on aggrecan expression and the NAT2 genotype in cell donors.

METHODS

NP cells were isolated from intervertebral disc tissues donated by 31 Japanese patients (28-68 years) who underwent discectomy. NTP was added to the primary cell cultures and its effect on the aggrecan mRNA was analyzed using real-time quantitative PCR. To assess acetylator status, genotyping was performed based on the inferred NAT2 haplotypes of five common single-nucleotide polymorphisms using allele-specific PCR.

RESULTS

The phenotype frequencies of NAT2 in the patients were 0%, 42.0%, and 58.0% for slow, intermediate, and rapid acetylators, respectively. The proportions of responders to NTP treatment (aggrecan upregulation, ≥ 1.1-fold) in the intermediate and rapid acetylators were 76.9% and 38.9%, respectively. The odds ratio of the comparison of the intermediate acetylator status between responders and nonresponders was 5.2 (95% CI 1.06-26.0, P = 0.036), and regarding the 19 male patients, this was 14.0 (95% CI 1.54-127.2, P = 0.012). In the 12 females, the effect was not correlated with NAT2 phenotype but seemed to become weaker along with aging.

CONCLUSIONS

An intermediate acetylator status significantly favored the efficacy of NTP treatment to enhance aggrecan production in NP cells. In males, this tendency was detected with higher significance. This study provides suggestive data of the association between NAT2 variants and the efficacy of NTP treatment. Given the small sample size, results should be further confirmed.

Jinmaitong ameliorates diabetes-induced peripheral neuropathy in rats through Wnt/β-catenin signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Jinmaitong (JMT) is a prescription of Traditional Chinese Medicine, which is composed of ten herbal drugs and two animal drugs. It has long been used for the treatment of diabetic peripheral neuropathy (DPN).

AIM OF STUDY

Wnt/β-catenin pathway is considered as an essential and direct driver of myelinogenesis. This study aims to evaluate the protective effect of JMT against DPN dynamically during a 16-weeks' treatment, and to investigate the underlying mechanism in which the Wnt/β-catenin pathway is involved.

MATERIALS AND METHODS

Diabetic model was induced by single intraperitoneal injection of Streptozotocin (STZ) using male Sprague-Dawley rats. The model rats were divided into five groups and administrated with JMT at three doses (0.437, 0.875, and 1.75 g/kg per day), neurotropin (positive drug, 2.67 NU/kg per day), and placebo (deionized water), respectively, for continuous 8 weeks (n = 9-10), 12 weeks (n = 8-10), or 16 weeks (n = 7-9). Meanwhile, rats in control group were administrated with placebo (n = 10 for 8 weeks, n = 9 for 12 and 16 weeks, respectively). Blood glucose and body weight were monitored every four weeks. Mechanical allodynia was assessed using mechanical withdrawal threshold (MWT) test. The morphological change of sciatic nerves were observed by transmission electron microscope (TEM) and hematoxylin and eosin (HE) stain. The mRNA and protein levels of targeted genes were evaluated by quantitative real time-PCR and western bolt, respectively. Myelin protein zero (MPZ) and mediators involved in Wnt/β-catenin pathway, such as β-catenin, glycogen synthase kinase 3β (GSK-3β), and WNT inhibitory factor-1 (WIF-1), were compared among different groups after treatment of 8, 12, and 16 weeks, respectively.

RESULTS

The mechanical allodynia and peripheral nerve morphology were degenerated in DPN rats over time, and notably improved after JMT-treatment of 12 and 16 weeks. The decreased MPZ level in DPN rats were also significantly amended by JMT. More importantly, we found that the suppressed Wnt/β-catenin pathway in sciatic nerves of DPN rats was overtly up-regulated by JMT in a time-dependent manner. Among the three doses, JMT at the middle dose showed the best effect.

CONCLUSIONS

JMT effectively ameliorated diabetic-induced peripheral neuropathy, which was mediated by the activation of Wnt/β-catenin signaling pathway. This study provided new perspective to understand the neuroprotective mechanism of JMT.

Kelly M, M. Buchowski J, P. Zebala L, Luhmann S, C. Gupta M, A. Setton L. Verteporfin treatment controls morphology, phenotype, and global gene expression for cells of the human nucleus pulposus

Cells of the nucleus pulposus (NP) are essential contributors to extracellular matrix synthesis and function of the intervertebral disc. With age and degeneration, the NP becomes stiffer and more dehydrated, which is associated with a loss of phenotype and biosynthetic function for its resident NP cells. Also, with aging, the NP cell undergoes substantial morphological changes from a rounded shape with pronounced vacuoles in the neonate and juvenile, to one that is more flattened and spread with a loss of vacuoles. Here, we make use of the clinically relevant pharmacological treatment verteporfin (VP), previously identified as a disruptor of yes-associated protein-TEA domain family member-binding domain (TEAD) signaling, to promote morphological changes in adult human NP cells in order to study variations in gene expression related to differences in cell shape. Treatment of adult, degenerative human NP cells with VP caused a shift in morphology from a spread, fibroblastic-like shape to a rounded, clustered morphology with decreased transcriptional activity of TEAD and serum-response factor. These changes were accompanied by an increased expression of vacuoles, NP-specific gene markers, and biosynthetic activity. The contemporaneous observation of VP-induced changes in cell shape and prominent, time-dependent changes within the transcriptome of NP cells occurred over all timepoints in culture. Enriched gene sets with the transition to VP-induced cell rounding suggest a major role for cell adhesion, cytoskeletal remodeling, vacuolar lumen, and MAPK activity in the NP phenotypic and functional response to changes in cell shape.

Neurotropin Inhibits Lipid Accumulation by Maintaining Mitochondrial Function in Hepatocytes via AMPK Activation

The accumulation of lipid droplets in the cytoplasm of hepatocytes, known as hepatic steatosis, is a hallmark of non-alcoholic fatty liver disease (NAFLD). Inhibiting hepatic steatosis is suggested to be a therapeutic strategy for NAFLD. The present study investigated the actions of Neurotropin (NTP), a drug used for chronic pain in Japan and China, on lipid accumulation in hepatocytes as a possible treatment for NAFLD. NTP inhibited lipid accumulation induced by palmitate and linoleate, the two major hepatotoxic free fatty acids found in NAFLD livers. An RNA sequencing analysis revealed that NTP altered the expression of mitochondrial genes. NTP ameliorated palmitate-and linoleate-induced mitochondrial dysfunction by reversing mitochondrial membrane potential, respiration, and β-oxidation, suppressing mitochondrial oxidative stress, and enhancing mitochondrial turnover. Moreover, NTP increased the phosphorylation of AMPK, a critical factor in the regulation of mitochondrial function, and induced PGC-1β expression. Inhibition of AMPK activity and PGC-1β expression diminished the anti-steatotic effect of NTP in hepatocytes. JNK inhibition could also be associated with NTP-mediated inhibition of lipid accumulation, but we did not find the association between AMPK and JNK. These results suggest that NTP inhibits lipid accumulation by maintaining mitochondrial function in hepatocytes via AMPK activation, or by inhibiting JNK.

Jinmaitong, a Traditional Chinese Compound Prescription, Ameliorates the Streptozocin-Induced Diabetic Peripheral Neuropathy Rats by Increasing Sciatic Nerve IGF-1 and IGF-1R Expression

Jinmaitong (JMT) is a Traditional Chinese Compound Prescription for the treatment of diabetic peripheral neuropathy (DPN). This study aims to investigate the effect of JMT on the insulin-like growth factor 1 (IGF-1) and the insulin like growth factor 1 receptor (IGF-1R) expression in sciatic nerves of diabetic rats. Firstly, the chemical profile of JMT was characterized by UPLC/Q-TOF-MS analysis. A total of 72 compounds were putatively identified. Secondly, streptozotocin (STZ)-induced diabetic rats were treated with neurotropin (NTP, 2.67 NU/kg/day) or JMT at low-dosage (0.4375 g/kg/day), medium-dosage (0.875 g/kg/day), and high-dosage (1.75 g/kg/day) for continuous 16 weeks. Blood glucose and body weight were detected every 4 weeks during the experiment. The mechanical pain and morphological change on sciatic nerves were detected by pain measurement instrument and microscopy. The IGF-1 level in serum and tissues were measured though ELISA and immunohistochemistry. The mRNA and protein expressions of IGF-1, IGF-1R, peripheral myelin protein zero (P0), and peripheral myelin protein 22 (PMP22) in the tissues were measured by qRT-PCR and western blot. As a result, JMT had no significant effect on body weight, but reduced the fasting blood glucose levels of diabetic rats. Besides, the pathological morphology, mechanical pain thresholds, serum level and tissue expression of IGF-1, mRNA, and protein levels of IGF-1R, P0, and PMP22 were significantly improved in JMT group at middle dosage. In conclusion, JMT could ameliorate the behavioristics and morphology changes in DPN rats by promoting IGF-1 and IGF-1R gene and protein expressions in sciatic nerves, as well as regulating the peripheral nerve remyelination genes P0 and PMP22 expressions, which provides scientific evidence for the clinical application of JMT in DPN patients.

Neurotropin reduces memory impairment and neuroinflammation via BDNF/NF-κB in a transgenic mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurodegenerative disease with limited treatments and no cure. Neurotropin (NTP) is an analgesic drug widely prescribed for neuropathic pain. Increasing evidence suggests that NTP may also protect against neurodegeneration, but NTP's treatment potential against memory impairments of AD remains to be explored. APP/PS1 mice, which model AD, were given NTP for three months then cognitively tested with the Morris water maze. Their Aβ burden, microglial and astrocytic activation, and BDNF levels were compared to untreated controls using immunofluorescent staining. Expression of pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) and NF-κB pathway related proteins (p65 and IκB-α) were examined by ELISA or Western blots in vivo and in vitro in the microglia cell line. Lastly, BV-2 cells were pre-treated with the selective BDNF inhibitor ANA-12 and with NTP to examine mechanistic pathways. Taken together, NTP treatment reduced cognitive impairment, Aβ deposits, and glial activation in cortex and hippocampus APP/PS1 mice. IL-1β, IL-6 and TNF-α also decreased after NTP treatment in vivo and in vitro, and BDNF levels rose. Also, NTP reduced p65 and IκB-α activation and the effect of NTP on pro-inflammatory cytokines and NF-κB pathway related proteins was abolished by BDNF inhibitor. Our results indicate that NTP reduces neuroinflammation and improves the cognitive deficits in APP/PS1 mice possibly via BDNF/NF-κB pathway. NTP may be a new promising drug candidate for patients with AD.