IntroductionThe degenerate intervertebral disc (IVD) becomes innervated by sensory nerve fibres, and vascularised by blood vessels. This study aimed to identify neurotrophins, neuropeptides and angiogenic factors within native IVD tissue and to further investigate whether pro-inflammatory cytokines are involved in the regulation of expression levels within nucleus pulposus (NP) cells, nerve and endothelial cells.MethodsQuantitative real-time PCR (qRT-PCR) was performed on 53 human IVDs from 52 individuals to investigate native gene expression of neurotrophic factors and their receptors, neuropeptides and angiogenic factors. The regulation of these factors by cytokines was investigated in NP cells in alginate culture, and nerve and endothelial cells in monolayer using RT-PCR and substance P (SP) protein expression in interleukin-1 (IL-1β) stimulated NP cells.ResultsInitial investigation on uncultured NP cells identified expression of all neurotrophins by native NP cells, whilst the nerve growth factor (NGF) receptor was only identified in severely degenerate and infiltrated discs, and brain derived neurotrophic factor (BDNF) receptor expressed by more degenerate discs. BDNF expression was significantly increased in infiltrated and degenerate samples. SP and vascular endothelial growth factor (VEGF) were higher in infiltrated samples. In vitro stimulation by IL-1β induced NGF in NP cells. Neurotropin-3 was induced by tumour necrosis factor alpha in human dermal microvascular endothelial cells (HDMECs). SP gene and protein expression was increased in NP cells by IL-1β. Calcitonin gene related peptide was increased in SH-SY5Y cells upon cytokine stimulation. VEGF was induced by IL-1β and interleukin-6 in NP cells, whilst pleiotrophin was decreased by IL-1β. VEGF and pleiotrophin were expressed by SH-SY5Y cells, and VEGF by HDMECs, but were not modulated by cytokines.ConclusionsThe release of cytokines, in particular IL-1β during IVD degeneration, induced significant increases in NGF and VEGF which could promote neuronal and vascular ingrowth. SP which is released into the matrix could potentially up regulate the production of matrix degrading enzymes and also sensitise nerves, resulting in nociceptive transmission and chronic low back pain. This suggests that IL-1β is a key regulatory cytokine, involved in the up regulation of factors involved in innervation and vascularisation of tissues.

IntroductionThe aims of these studies were to identify the cytokine and chemokine expression profile of nucleus pulposus (NP) cells and to determine the relationships between NP cell cytokine and chemokine production and the characteristic tissue changes seen during intervertebral disc (IVD) degeneration.MethodsReal-time q-PCR cDNA Low Density Array (LDA) was used to investigate the expression of 91 cytokine and chemokine associated genes in NP cells from degenerate human IVDs. Further real-time q-PCR was used to investigate 30 selected cytokine and chemokine associated genes in NP cells from non-degenerate and degenerate IVDs and those from IVDs with immune cell infiltrates (‘infiltrated’). Immunohistochemistry (IHC) was performed for four selected cytokines and chemokines to confirm and localize protein expression in human NP tissue samples.ResultsLDA identified the expression of numerous cytokine and chemokine associated genes including 15 novel cytokines and chemokines. Further q-PCR gene expression studies identified differential expression patterns in NP cells derived from non-degenerate, degenerate and infiltrated IVDs. IHC confirmed NP cells as a source of IL-16, CCL2, CCL7 and CXCL8 and that protein expression of CCL2, CCL7 and CXCL8 increases concordant with histological degenerative tissue changes.ConclusionsOur data indicates that NP cells are a source of cytokines and chemokines within the IVD and that these expression patterns are altered in IVD pathology. These findings may be important for the correct assessment of the ‘degenerate niche’ prior to autologous or allogeneic cell transplantation for biological therapy of the degenerate IVD.

The basic science underlying the process of bone healing has been a topic of intense research activity over the past 50 years. Increasing understanding of events on a molecular level has allowed a greater understanding of factors that might contribute to failure of these mechanisms. From this it has been possible to introduce new treatment methods as adjuncts to traditional methods, both for fresh fractures and for established non-unions. Knowledge of these topics is essential to the day to day practice of the majority of orthopaedic consultants and as such is a favourite topic of examiners in both basic surgical and specialist orthopaedic examinations. The first half of this article summarizes current understanding of the biology of bone healing, highlighting recent advances. The second part is an overview of the aetiology and management of non-union.

Nerve and blood vessel ingrowth during intervertebral disc degeneration, is thought to be a major cause of low back pain, however the regulation of this process is poorly understood. Here, we investigated the expression and regulation of a subclass of axonal guidance molecules known as the class 3 semaphorins, and their receptors; plexins and neuropilins within human NP tissue and their regulation by pro-inflammatory cytokines. Importantly this determined whether semaphorin expression was associated with the presence of nerves and blood vessels in tissues from human intervertebral discs. The study demonstrated that semaphorin3A, 3C, 3D, 3E and 3F and their receptors were expressed by native NP cells and further demonstrated their expression was regulated by IL-1β but to a lesser extent by IL-6 and TNFα. This is the first study to identify sema3C, sema3D and their receptors within the nucleus pulposus of intervertebral discs. Immunopositivity shows significant increases in semaphorin3C, 3D and their receptor neuropilin-2 in degenerate samples which were shown to contain nerves and blood vessels, compared to non-degenerate samples without nerves and blood vessels. Therefore data presented here suggests that semaphorin3C may have a role in promoting innervation and vascularisation during degeneration, which may go on to cause low back pain.

Background: the exact etiology of adolescent idiopathic scoliosis (aiS) is unknown, but recently, vitamin d has been suggested to be of importance in the pathophysiology of aiS. this article sought to (1) highlight the prevalence of vitamin d deficiency in patients undergoing corrective surgery for aiS within the united kingdom and (2) evaluate the correlation and clinical relevance of preoperative back pain with vitamin d deficiency.Methods: data were collected on 201 consecutive patients undergoing corrective surgery for aiS. Baseline data included patient demographics, medical diagnoses, and standing preoperative Cobb angles. all patients had a preoperative 25-hydroxyvitamin d level recorded. one hundred ninety-six patients completed preoperative Scoliosis Research Society-22 outcome scores to quantify preoperative back pain.Results: a total of 177 (89%) patients were young women, and the mean age at time of surgery was 14.9 years (13-18 years). all patients were diagnosed with aiS. the mean Cobb angles at time of surgery was 64°. only 11 (5.5%) patients had "normal" vitamin d levels (>75 nmol/l), with 147 (74%) patients having deficient levels requiring treatment with supplementation. there was no correlation between vitamin d levels and preoperative Cobb angles (r s = −0.12), and there was a moderate correlation identified between the severity of preoperative vitamin d levels and preoperative back pain scores (r s =0.42).Conclusion: Vitamin d deficiency is common in patients with aiS; however, it is comparable to the national prevalence of vitamin d deficiency in healthy adolescent children. there was a strong correlation between preoperative back pain scores and the severity of vitamin d deficiency. these findings suggest that all patients with aiS should be screened for vitamin d deficiency and that supplementation where appropriate may lead to improved pain scores.Clinical Relevance: if vitamin d is prevelant and if vitamin d deficiency is found to cause back pain, then there is an easy/cheap/safe treatement with supplementation.