Chronic low back pain is strongly linked to degeneration of the intervertebral disc (IVD), which currently lacks any targeted treatments. This study explores NPgel, a biomaterial combined with notochordal cells (NC), developmental precursor cells, as a potential solution. NCs, known for anti-catabolic effects on IVD cells, present a promising avenue for regenerating damaged IVD tissue. Bovine IVDs underwent enzymatic degeneration before NPgel (+/- NC) injection. Degenerated bovine IVDs were cultured under biomechanical loading for 21 days. Histology and immunohistochemistry assessed NC survival, phenotype, and matrix production. Within an Background
Methods
Low back pain affects 80% of the population with half of cases attributed to intervertebral disc (IVD) degeneration. However, the majority of treatments focus on pain management, with none targeting the underlying pathophysiological causes. PCRX-201 presents a novel gene therapy approach that addresses this issue. PCRX-201 codes for interleukin-1 receptor antagonist (IL-1Ra), the natural inhibitor of the pro-inflammatory cytokine IL-1, which orchestrates the catabolic degeneration of the IVD. Our objective here is to determine the ability of PCRX-201 to infect human nucleus pulposus (NP) cells and tissue to increase the production of IL-1Ra and assess downstream effects on catabolic protein production. Degenerate human NP cells and tissue explants were infected with PCRX-201 at 0 or 3000 multiplicities of infection (MOI) and subsequently cultured for 5 days in monolayer (n=7), 21 days in alginate beads (n=6) and 14 days in tissue explants (n=5). Cell culture supernatant was collected throughout culture duration and downstream targets associated with pain and degeneration were assessed using ELISA. IL-1Ra production was increased in NP cells and tissue infected with PCRX-201. The production of downstream catabolic proteins such as IL-1β, IL-6, MMP3, ADAMTS4 and VEGF was decreased in both 3D-cultured NP cells and tissue explants. Here, we have demonstrated that a novel gene therapy, PCRX-201, is able to infect and increase the production of IL-1Ra in degenerate NP cells and tissue in vitro. The increase of IL-1Ra also resulted in a decrease in the production of a number of pro-inflammatory and catabolic proteins, suggesting PCRX-201 enables the inhibition of IL-1-driven IVD degeneration. At present, no treatments for IVD degeneration target the underlying pathology. The ability of FX201 to elicit anti-catabolic responses is promising and warrants further investigation in vitro and in vivo, to determine the efficacy of this exciting, novel gene therapy.
Low back pain resulting from Interertebral disc (IVD) degeneration is a serious worldwide problem, with poor treatment options available. Notochordal (NC) cells, are a promising therapeutic cell source with anti-catabolic and regenerative effect. However, their behaviour in the harsh degenerate environment is unknown. Porcine NC cells (pNCs), and Human NP cells from degenerate IVDs were cultured in alginate beads to maintain phenotype. Cells were cultured alone or in combination, or co-stimulated with notochordal cell condition media (NCCM), in media to mimic the healthy and degenerate disc environment, together with controls for up to 1 week. Following culture viability, qPCR and proteomic analysis using Digiwest was performed. A small increase in pNC cell death was observed in degenerated media compared to standard and healthy media, with a further decrease seen when cultured with IL-1β. Whilst no significant differences were seen in phenotypic marker expression in pNCs cultured in any media at gene level (ACAN, KRT8, KRT18, FOXA2, COL1A1 and Brachyury). Preliminary Digiwest analysis showed increased protein production for Cytokeratin 18, src and phosphorylated PKC but a decrease in fibronectin in degenerated media compared to standard media. Human NP cells cultured with NCCM, showed a decrease in IL-8 production compared to human NP cells alone when cultured in healthy media. However, gene expression analysis (ACAN, VEGF, MMP3 and IL-1β) demonstrated no significant difference between NP only and NP+NCCM groups. Studying the behaviour of the NCs in in vitro conditions that mimic the in vivo healthy or degenerate niche will help us to better understand their potential for therapeutic approaches. The potential use of NC cell sources for regenerative therapies can then be translated to investigate the potential use of iPSCs differentiated into NC cells as a regenerative cell source.
Low back pain is strongly associated with degeneration of the intervertebral disc (IVD). During degeneration, altered matrix synthesis and increased matrix degradation, together with accompanied cell loss is seen particularly in the nucleus pulposus (NP). It has been proposed that notochordal (NC) cells, embryonic precursors for the cells within the NP, could be utilized for mediating IVD regeneration. However, injectable biomaterials are likely to be required to support their phenotype and viability within the degenerate IVD. Therefore, viability and phenotype of NC cells were analysed and compared within biomaterial carriers subjected to physiological oxygen conditions over a four-week period were investigated. Porcine NC cells were incorporated into three injectable hydrogels: NPgel (a L-pNIPAM-co-DMAc hydrogel), NPgel with decellularized NC-matrix powder (dNCM) and Albugel (an albumin/ hyaluronan hydrogel). The NCs and biomaterials constructs were cultured for up to four weeks under 5% oxygen (n=3 biological repeats). Histological, immunohistochemical and glycosaminoglycans (GAG) analysis were performed to investigate NC viability, phenotype and extracellular matrix synthesis and deposition. Histological analysis revealed that NCs survive in the biomaterials after four weeks and maintained cell clustering in NPgel, Albugel and dNCM/NPgel with maintenance of morphology and low caspase 3 staining. NPgel and Albugel maintained NC cell markers (brachyury and cytokeratin 8/18/19) and extracellular matrix (collagen type II and aggrecan). Whilst Brachyury and Cytokeratin were decreased in dNCM/NPgel biomaterials, Aggrecan and Collagen type II was seen in acellular and NC containing dNCM/NPgel materials. NC containing constructs excreted more GAGs over the four weeks than the acellular controls. NC cells maintain their phenotype and characteristic features in vitro when encapsulated into biomaterials. NC cells and biomaterial construct could potentially become a therapy to treat and regenerate the IVD.
Low back pain resulting from Intervertebral disc (IVD) degeneration is a serious worldwide problem, with poor treatment options available. Notochordal (NC) cells, are a promising therapeutic cell source with anti-catabolic and regenerative effect, however, their behaviour in the harsh degenerate environment is unknown. Thus, we aimed to investigate and compare their physiological behaviour in Porcine NC cells were encapsulated in 3D alginate beads to maintain their phenotype then cultured in media to mimic the healthy and degenerate disc environment, together with control NC media for 1 week. Following which viability using PI and Calcein AM, RNA extraction and RT-PCR for NC cell markers, anabolic and catabolic genes analysed. Proteomic analysis was also performed using Digiwest technology.Backgrounds and aim
Methodology
Low back pain is strongly associated with degeneration of the intervertebral disc (IVD). During degeneration, altered matrix synthesis and increased matrix degradation, together with accompanied cell loss is seen particularly in the nucleus pulposus (NP). It has been proposed that notochordal (NC) cells, embryonic precursors for the cells within the NP, could be utilized for mediating IVD regeneration. However, injectable biomaterials are likely to be required to support their phenotype and viability within the degenerate IVD. Therefore, viability and phenotype of NC cells were analysed and compared within biomaterial carriers subjected to physiological oxygen conditions over a four-week period were investigated. Porcine NC cells were incorporated into three injectable hydrogels: NPgel (a L-pNIPAM-co-DMAc hydrogel), NPgel with decellularized NC-matrix powder (dNCM) and Albugel (an albumin/ hyaluronan hydrogel). The NCs and biomaterials constructs were cultured for up to four weeks under 5% oxygen (n=3 biological repeats). Histological, immunohistochemical and glycosaminoglycans (GAG) analysis were performed to investigate NC viability, phenotype and extracellular matrix synthesis and deposition.Objectives
Methodology
Current clinical treatment for spinal instability requires invasive spinal fusion with cages and screw instrumentation. We previously reported a novel injectable hydrogel (Bgel), which supports the delivery and differentiation of mesenchymal stem cells (MSCs) to bone forming cells and supports bone formation Bovine and Human Nucleus pulpous tissue explants were injected with Bgel with and without MSCs. Tissue samples were cultured under hypoxia (5%) in standard culture media for 4 weeks. Cell viability, histological assessment of matrix deposition, calcium formation, and cell phenotype analysis using immunohistochemistry for NP matrix and bone markers.Background
Methodology
We have previously reported an injectable hydrogel (NPgel), which could deliver patients own stem cells, via small bore needles, decreasing damage to the annulus fibrosus. NPgel drives differentiation to NP cells and can inhibit the degenerate niche. However, clinical success of NPgel is dependent on the capacity to inject NPgel into naturally degenerate human discs, restore mechanical function to the IVD, prevent extrusion during loading and induce regeneration. This study assessed injectability of NPgel into human IVD, influence on mechanical properties, regeneration ability in an Cadaveric human discs were used to calculate disc height and to determine Youngs Modulus during simulated walking pre and post injection of NPgel, extrusion testing performed. Whole human IVDs were injected with NPgel +/− human BMPCs and maintained in culture under physiological loading regime for 4 weeks. Pre and post culture MRI imaging and in line biomechanical characteristics determined. Histology and immunochemistry performed for anabolic and catabolic factors.Background
Methodology
Intervertebral disc (IVD) degeneration accompanying with low back pain is a serious worldwide problem. Even though, surgical treatments are available for pain relief, there is an urgent need to establish enduring cell-based remedies. Notochordal (NC) cells as the ancestor of nucleus pulposus (NP) cells in human IVD are a promising therapeutic target. It has been reported that the loss of NC cells after childhood could promote the onset of disc degeneration. Thus, we firstly, aimed to optimise the culture of NC cells in vitro without using the FCS in alginate (3D) culture systems, secondly, investigate their behaviour in healthy and degenerate niche and lastly, co-culture these cells with degenerated NP cells to assess their regeneration potentials. Porcine NC cells were extracted using pronase treatment followed by overnight digestion in 0.01% collagenase II. After extraction, cells were culture in 1.2% alginate beads (gold standard 3D culture) in either low glucose DMEM or αMEM medium. Cells were harvested after 24 hours, 1 week and 2 weeks for gene expression analysis and formalin fixed paraffin embedding. Quantitative Real-Time PCR and Immuno-staining were performed for analysis of NC markers (KRT18, FOXA2 and T) and COL I as a negative marker. Next, NC cells were cultured in healthy and degenerate medium to assess their viability and behaviour.Introduction and Objective
Materials and Methods
Injectable hydrogels via minimally invasive surgery offer benefits to the healthcare system, reduced risk of infection, scar formation and the cost of treatment. Development of new treatments with the use of novel biomaterials requires significant pre-clinical testing and must comply with regulations before they can reach the bedside. In the European economic area (EEA) one of the first hurdles of this process is attaining the CE marking which protects the health, safety and environmental aspects of a product. Implanted materials fall under the class III medical device EU745 regulation standards. To attain the CE marking for a product parties must provide evidence of the materials safety with an investigational medicinal product dossier (IMPD). We have been working to develop a new thermoresponsive injectable biomaterial hydrogel (NPgel) for the treatment of intervertebral disc (IVD) disease. A large part of the IMPD requires information on how the hydrogel physical properties change over time in bodily conditions. We have been studying 6 batches of NPgel over 18 months, tracking the materials wet/ dry weight, structure and composition. To date we have found that NPgel in liquids more similar to the body (with protein and salts) appear to be stable and safe, whilst those in distilled water swell and disintegrate over time. Subtle long-term changes to the material composition were found and we are currently investigating its ramifications.Introduction
Methods and Results
We have developed a new synthetic hydrogel that can be injected directly into the intervertebral disc (IVD) without major surgery. Designed to improve fixation of joint prosthesis, support bone healing or improve spinal fusion, the liquid may support the differentiation of native IVD cells towards osteoblast-like cells cultured within the hydrogel. Here we investigate the potential of this gel system (Bgel) to induce bone formation within intervertebral disc tissue. IVD tissue obtained from patients undergoing discectomy, or cadaveric samples, were cultured within a novel explant device. The hydrogel was injected, with and without mesenchymal stem cells (MSCs), and cultured under hypoxia, to mimic the degenerate IVD environment, for 4 weeks. Explants were embedded to wax and native cellular migration into the hydrogel was investigated, together with cellular phenotype and matrix deposition.Introduction
Methods
The intervertebral disc is constantly subjected to forces generated by movement. But degeneration can disrupt normal biomechanics, generating uneven and complex loading patterns. Evidence suggests that these forces are converted into voltages through different mechanisms, such as streaming potentials. This implicates voltage-gated ion channels in the biological remodelling response of the disc to loading. These signalling pathways have not been studied, and this incomplete understanding of disc mechanotransduction may hinder regenerative therapies. The purpose of this study is to identify and determine the role of voltage-gated ion channels in the intervertebral disc and to investigate any changes in degeneration. Primary bovine and human disc cells were cultured in monolayer or alginate beads for experiments. Cells were treated with altered osmolarity alone or in combination with IL-1β. Ion flux was measured through calcium influx and will be further investigated using the xCelligence RTCA CardioECR. Immunohistochemistry was performed on human and bovine discs to evaluate expression levels of ion channels. RNA was extracted from bovine NP cells and will be analysed through PCR/Microarray for gene expression.Purpose and Background
Methods and Results
We have previously reported the development of injectable hydrogels for potential disc regeneration (NPgel) or bone formation which could be utilized in spinal fusion (Bgel). As there are multiple sources of mesenchymal stem cells (MSCs), this study investigated the incorporation of patient matched hMSCs derived from adipose tissue (AD) and bone marrow (BM) to determine their ability to differentiate within both hydrogel systems under different culture conditions. Human fat pad and bone marrow derived MSCs were isolated from femoral heads of patients undergoing hip replacement surgery for osteoarthritis with informed consent. MSCs were encapsulated into either NPgel or Bgel and cultured for up to 6 weeks in 5% (NPgel) or 21% (Bgel) O2. Histology and immunohistochemistry was utilized to determine phenotype. Both fat and bone marrow derived MSCs, were able to differentiate into both cell lineages. NPgel culture conditions increased expression of matrix components such as collagen II and aggrecan and NP phenotypic markers FOXF1 and PAX1, whereas Bgel induced expression of collagen I and osteopontin, indicative of osteogenic differentiation.Purpose of study and background
Methods and Results
Low back pain affects 80% of the population at some point in their lives with 40% of cases attributed to intervertebral disc (IVD) degeneration. A number of potential regenerative approaches are under investigation worldwide, however their translation to clinic is currently hampered by an appropriate model for testing prior to clinical trials. Therefore, a more representative large animal model for IVD degeneration is needed to mimic human degeneration. Here we investigate a caprine IVD degeneration model in a loaded disc culture system which can mimic the native loading environment of the disc. Goat discs were excised and cultured in a bioreactor under diurnal, simulated-physiological loading (SPL) conditions, following 3 days pre load, IVDs were degenerated enzymatically for 2hrs and subsequently loaded for 10 days under physiological loading. A PBS injected group was used as controls. Disc deformation was continuously monitored and changes in disc height recovery quantified using stretched-exponential fitting. Histological staining was performed on caprine discs to assess extracellular matrix production and immunohistochemistry performed to determine expression of catabolic protein expression. The injection of collagenase and cABC induced mechanical behavior akin to that seen in human degeneration. A decrease in collagens and glycosaminoglycans (GAGs) was seen in enzyme injected discs, which was accompanied by increased cellular expression for degradative enzymes and catabolic cytokines.Purpose of study and background
Methods and Results
IVD degeneration is a major cause of Low back pain. We have previously reported an injectable hydrogel (NPgel), which induces differentiation of human MSCs to disc cells and integrates with NP tissue following injection MSCs were cultured in NP gel under 5% O2 in either: standard culture (DMEM, pH7.4); healthy disc (DMEM, pH7.1); degenerate disc (low glucose DMEM, pH6) or degenerate disc plus IL-1β. Following 4 weeks histological staining and immunohistochemical analysis investigated viability, ECM synthesis and matrix degrading enzyme expression. Here we have shown that viability and NP cell differentiation of MSCs incorporated within NPgel was mostly unaffected by treatment with conditions such as low glucose, low pH and the presence of cytokines, all regarded as key contributors to disc degeneration. In addition, the NPgel was shown to prevent MSCs from displaying a catabolic phenotype with low expression of degradative enzymes, highlighting the potential of NPgel to differentiate hMSCs and protect them from the degenerate disc microenvironment.Purpose of study and background
Methods and Results
The intervertebral disc (IVD) is a highly hydrated and hyperosmotic tissue, water and salt content fluctuate daily due to mechanical loading. Resident IVD cells must adapt to this ever-changing osmotic environment, to maintain normal behaviour. However, during IVD degeneration the disc becomes permanently dehydrated and cells can no longer perform their correct function. Here, we investigated how human nucleus pulposus (NP) cells respond to altered osmolality with regards to cell size and the rate of water permeability, along with the potential involvement of aquaporins (AQPs) and transient receptor potential vanilloid (TRPV) membrane channels. Water permeability of NP cells exposed to altered osmolality (225–525mOsm/kg) in the presence or absence of AQP and TRPV channel inhibitors was investigated with the cell-permeable calcein-AM fluorescent dye, and cell size determined using microscopy and flow cytometry.Introduction
Methods
Intervertebral disc (IVD) degeneration is a major cause of low back pain (LBP). We have developed an injectable hydrogel (NPgel), which following injection into bovine IVD explants, integrates with IVD tissue and promotes disc cell differentiation of delivered mesenchymal stem cells (MSCs) without growth factors. Here, we investigated the injection of NPgel+MSCs into IVD explants under degenerate culture conditions. The NPgel integrated with bovine and human degenerate Nucleus Pulposus (NP) tissue and hMSCs produced matrix components: aggrecan, collagen type II and chondroitin sulphate in standard and degenerate culture conditions. Significantly increased cellular immunopositivty for aggrecan was observed within native NP cells surrounding the site where NPgel+MSCs were injected (P≤0.05). In NP explants a significant decrease in catabolic factors were observed where NPgel+MSCs was injected in comparison to controls.Background
Methods and Results
Intervertebral disc (IVD) degeneration is a major cause of low back pain (LBP). Degenerate discs are associated with accelerated cellular senescence. Cell senescence is associated with a secretory phenotype characterised by increased production of catabolic enzymes and cytokines. However to date, the mechanism of cell senescence within disc degeneration is unclear. Senescence can be induced by increased replication or induced by stress such as reactive oxygen species or cytokines. This study investigated the association of cellular senescence with markers of DNA damage and presence of cytoplasmic DNA (which in cancer cells has been shown to be a key regulator of the secretory phenotype), to determine mechanisms of senescence in disc degeneration. Immunohistochemistry for the senescence marker: p16INK4A was firstly utilised to screen human intervertebral discs for discs displaying at least 30% immunopostivity. These discs were then subsequently analysed for immunopostivity for DNA damage markers γH2AX and cGAS and the presence of cytoplasmic DNA. The number of immunopositive cells for p16INK4A positively correlated with the expression of γH2AX and cGAS. Senescent cells were also associated with the presence of cytoplasmic DNA.Background
Methods and Results
The IVD is a highly hydrated, hyperosmolar tissue that allows the correct biomechanical function of the spine. When degenerated, water and ions are lost from the disc, especially within the central nucleus pulposus (NP), producing a hypoosmotic environment in which the resident cells can no longer function correctly, exacerbating the degenerative cascade. One potential way that IVD cells may adapt to their environment is through the expression and regulation of aquaporin (AQP) channels that control the movement of water in and out of cells. During human IVD degeneration AQP1 and 5 expression is decreased, highlighting AQPs may be of importance for the correct function of NP cells. The regulation of AQPs in NP cells by healthy and degenerate conditions, and the potential underlying molecular mechanisms, were investigated in both human and rat IVD cells. The gene and protein expression of AQP1 and AQP5 was upregulated by hyperosmotic conditions (425mOsm/kg H2O) in rat and human NP cells. Lentiviral knockdown of tonicity enhancer binding protein (TonEBP), a transcription factor responsible for maintaining the function of NP cells, resulted in the loss of AQP1 and 5 gene expression under hyperosmotic conditions. The maintenance of the IVD environment and adaptation of cells is vital for the function of the IVD. The regulation of AQPs by physiological conditions and TonEBP suggests a role for these water channels related to the adaptation of disc cells to their environment, which is dysregulated during degeneration.
Intervertebral disc (IVD) degeneration is a major cause of low back pain (LBP). Degenerate discs are associated with accelerated cellular senescence. Cell senescence is associated with a secretory phenotype characterised by increased production of catabolic enzymes and cytokines. However, to date, the mechanism of cell senescence within disc degeneration is unclear. Senescence can be induced by increased replication or induced by stress such as reactive oxygen species or cytokines. This study investigated the association of cellular senescence with markers of DNA damage and presence of cytoplasmic DNA (which in cancer cells has been shown to be a key regulator of the secretory phenotype), to determine mechanisms of senescence in disc degeneration. Immunohistochemistry for the senescence marker: p16INK4A was firstly utilised to screen human intervertebral discs for discs displaying at least 30% immunopostivity. These discs were then subsequently analysed for immunopostivity for DNA damage markers γH2AX and cGAS and the presence of cytoplasmic DNA. The number of immunopositive cells for p16 INK4A positively correlated with the expression of γH2AX and cGAS. Senescent cells were also associated with the presence of cytoplasmic DNA. These new findings elucidated a role of cGAS and γH2AX as a link from genotoxic stress to cytokine expression which is associated with senescent cells. The findings indicate that cellular senescence
