Magnetic fields modulate metabolism and gut microbiome in correlation with Pgc-1α expression: Follow-up to an in vitro magnetic mitohormetic study.

Exercise modulates metabolism and the gut microbiome. Brief exposure to low mT-range pulsing electromagnetic fields (PEMFs) was previously shown to accentuate in vitro myogenesis and mitochondriogenesis by activating a calcium-mitochondrial axis upstream of PGC-1α transcriptional upregulation, recapitulating a genetic response implicated in exercise-induced metabolic adaptations. We compared the effects of analogous PEMF exposure (1.5 mT, 10 min/week), with and without exercise, on systemic metabolism and gut microbiome in four groups of mice: (a) no intervention; (b) PEMF treatment; (c) exercise; (d) exercise and PEMF treatment. The combination of PEMFs and exercise for 6 weeks enhanced running performance and upregulated muscular and adipose Pgc-1α transcript levels, whereas exercise alone was incapable of elevating Pgc-1α levels. The gut microbiome Firmicutes/Bacteroidetes ratio decreased with exercise and PEMF exposure, alone or in combination, which has been associated in published studies with an increase in lean body mass. After 2 months, brief PEMF treatment alone increased Pgc-1α and mitohormetic gene expression and after >4 months PEMF treatment alone enhanced oxidative muscle expression, fatty acid oxidation, and reduced insulin levels. Hence, short-term PEMF treatment was sufficient to instigate PGC-1α-associated transcriptional cascades governing systemic mitohormetic adaptations, whereas longer-term PEMF treatment was capable of inducing related metabolic adaptations independently of exercise.

Effect of BMI on the clinical outcome following microsurgical decompression in over-the-top technique: bi-centric study with an analysis of 744 patients.

PURPOSE: Decompression is one of the most common interventions in spinal surgery. Obesity has become an increasing issue in surgical patients. Therefore, the aim of this study was to analyze the clinical outcome following lumbar microsurgical decompression in correlation with the patient's body mass index (BMI). MATERIALS AND METHODS: A toal of 744 patients with spinal claudication that were seen at two specialized spine centers were included in this study. All patients underwent a bilateral microsurgical decompression in over-the-top technique. Patients were allocated in 4 groups based in their BMI category: 18.5-24.9 (n = 204), 25.0-29.9 (n = 318), 30.0-34.9 (n = 164) and ≥ 35 (n = 58). Clinical outcome data were recorded at baseline as well as 3, 12 and 24 months thereafter within a prospective study framework. The minimum follow-up was 12 months. For statistical analysis, data were adjusted for age, length of surgery and ASA and were analyzed by generalized linear gamma-based models. RESULTS: Postoperative changes in all outcome parameters were clearly dependent on BMI. Patients with higher BMI were characterized by inferior baseline values for VAS Back (p < 0.05). Over the follow-up period, the groups with BMI 30-34.9 and BMI ≥ 35 benefitted significantly less from the surgery than the two slimmer groups (p < 0.05). CONCLUSION: The data obtained from this large, homogenous cohort demonstrate that the quality of life improved substantially in all patients that were treated microsurgically for spinal stenosis. However, a BMI ≥ 30 may be considered as a negative predictor for a significantly inferior clinical outcome.

Extracellular Vesicles: Potential Mediators of Psychosocial Stress Contribution to Osteoporosis?

Osteoporosis is characterized by low bone mass and damage to the bone tissue's microarchitecture, leading to increased fracture risk. Several studies have provided evidence for associations between psychosocial stress and osteoporosis through various pathways, including the hypothalamic-pituitary-adrenocortical axis, the sympathetic nervous system, and other endocrine factors. As psychosocial stress provokes oxidative cellular stress with consequences for mitochondrial function and cell signaling (e.g., gene expression, inflammation), it is of interest whether extracellular vesicles (EVs) may be a relevant biomarker in this context or act by transporting substances. EVs are intercellular communicators, transfer substances encapsulated in them, modify the phenotype and function of target cells, mediate cell-cell communication, and, therefore, have critical applications in disease progression and clinical diagnosis and therapy. This review summarizes the characteristics of EVs, their role in stress and osteoporosis, and their benefit as biological markers. We demonstrate that EVs are potential mediators of psychosocial stress and osteoporosis and may be beneficial in innovative research settings.

Multiscale Regulation of the Intervertebral Disc: Achievements in Experimental, In Silico, and Regenerative Research.

Intervertebral disc (IVD) degeneration is a major risk factor of low back pain. It is defined by a progressive loss of the IVD structure and functionality, leading to severe impairments with restricted treatment options due to the highly demanding mechanical exposure of the IVD. Degenerative changes in the IVD usually increase with age but at an accelerated rate in some individuals. To understand the initiation and progression of this disease, it is crucial to identify key top-down and bottom-up regulations' processes, across the cell, tissue, and organ levels, in health and disease. Owing to unremitting investigation of experimental research, the comprehension of detailed cell signaling pathways and their effect on matrix turnover significantly rose. Likewise, in silico research substantially contributed to a holistic understanding of spatiotemporal effects and complex, multifactorial interactions within the IVD. Together with important achievements in the research of biomaterials, manifold promising approaches for regenerative treatment options were presented over the last years. This review provides an integrative analysis of the current knowledge about (1) the multiscale function and regulation of the IVD in health and disease, (2) the possible regenerative strategies, and (3) the in silico models that shall eventually support the development of advanced therapies.

Expression and activity of hyaluronidases HYAL-1, HYAL-2 and HYAL-3 in the human intervertebral disc.

PURPOSE: Hyaluronic acid plays an essential role in water retention of the intervertebral disc (IVD) and thus provides flexibility and shock absorbance in the spine. Hyaluronic acid gets degraded by hyaluronidases (HYALs), and some of the resulting fragments were previously shown to induce an inflammatory and catabolic response in human IVD cells. However, no data currently exist on the expression and activity of HYALs in IVD health and disease. METHODS: Gene expression, protein expression and activity of HYALs were determined in human IVD biopsies with different degrees of degeneration (n = 50 total). Furthermore, freshly isolated human IVD cells (n = 23 total) were stimulated with IL-1ß, TNF-α or H2O2, followed by analysis of HYAL-1, HYAL-2 and HYAL-3 gene expression. RESULTS: Gene expression of HYAL-1 and protein expression of HYAL-2 significantly increased in moderate/severe disc samples when compared to samples with no or low IVD degeneration. HYAL activity was not significantly increased due to high donor-donor variation, but seemed overall higher in the moderate/severe group. An inflammatory environment, as seen during IVD disease, did not affect HYAL-1, HYAL-2 or HYAL-3 expression, whereas exposure to oxidative stress (100 µM H2O2) upregulated HYAL-2 expression relative to untreated controls. CONCLUSION: Although HYAL-1, HYAL-2 and HYAL-3 are all expressed in the IVD, HYAL-2 seems to have the highest pathophysiological relevance. Nonetheless, further studies will be needed to comprehensively elucidate its significance and to determine its potential as a therapeutic target. These slides can be retrieved under Electronic Supplementary Material.

MicroRNAs in Intervertebral Disc Degeneration, Apoptosis, Inflammation, and Mechanobiology.

Intervertebral disc (IVD) degeneration is a multifactorial pathological process associated with low back pain, the leading cause of years lived in disability worldwide. Key characteristics of the pathological changes connected with degenerative disc disease (DDD) are the degradation of the extracellular matrix (ECM), apoptosis and senescence, as well as inflammation. The impact of nonphysiological mechanical stresses on IVD degeneration and inflammation, the mechanisms of mechanotransduction, and the role of mechanosensitive miRNAs are of increasing interest. As post-transcriptional regulators, miRNAs are known to affect the expression of 30% of proteincoding genes and numerous intracellular processes. The dysregulation of miRNAs is therefore associated with various pathologies, including degenerative diseases such as DDD. This review aims to give an overview of the current status of miRNA research in degenerative disc pathology, with a special focus on the involvement of miRNAs in ECM degradation, apoptosis, and inflammation, as well as mechanobiology.

Effects of Early Life Stress on Bone Homeostasis in Mice and Humans.

Bone pathology is frequent in stressed individuals. A comprehensive examination of mechanisms linking life stress, depression and disturbed bone homeostasis is missing. In this translational study, mice exposed to early life stress (MSUS) were examined for bone microarchitecture (µCT), metabolism (qPCR/ELISA), and neuronal stress mediator expression (qPCR) and compared with a sample of depressive patients with or without early life stress by analyzing bone mineral density (BMD) (DXA) and metabolic changes in serum (osteocalcin, PINP, CTX-I). MSUS mice showed a significant decrease in NGF, NPYR1, VIPR1 and TACR1 expression, higher innervation density in bone, and increased serum levels of CTX-I, suggesting a milieu in favor of catabolic bone turnover. MSUS mice had a significantly lower body weight compared to control mice, and this caused minor effects on bone microarchitecture. Depressive patients with experiences of childhood neglect also showed a catabolic pattern. A significant reduction in BMD was observed in depressive patients with childhood abuse and stressful life events during childhood. Therefore, future studies on prevention and treatment strategies for both mental and bone disease should consider early life stress as a risk factor for bone pathologies.

Sexual and urinary function following anterior lumbar surgery in females.

AIMS: Anterior lumbar interbody fusion procedures (ALIF) and total disc replacement (TDR) with anterior exposure of the lumbar spine entail a risk of a vascular injury and dysfunction of the sympathetic and parasympathetic nerves due to disturbance of the inferior and superior hypogastric plexus. While retrograde ejaculation is a known complication of the anterior spinal approach in males, post-operative sexual as well as urinary function in females has not yet been thoroughly investigated and was hence the aim of this study. METHODS: Fifteen female patients documented their sexual and urinary function preoperatively, 3 months and 6 months postoperatively, using the validated questionnaires FSFI (Female Sexual Function Index) and ICIQ (International Consultation of Incontinence Questionnaire). Randomization tests were used to statistically analyze expectation values over time (two-sided, P < 0.05). RESULTS: While no statistically significant change in the total FSFI score occurred over time, a significant increase in FSFI desire score was noted between preoperative (2.95 ± 0.8) and 6 months follow-up (3.51 ± 0.6, P = 0.02). Urinary continence remained unchanged over time. CONCLUSION: In summary, ALIF and lumbar TDR do not seem to negatively influence sexual and urinary function in females. In contrast, increased sexual desire was noted, likely secondary to post-surgical pain relief.

Expression and Activity of TRPA1 and TRPV1 in the Intervertebral Disc: Association with Inflammation and Matrix Remodeling.

Transient receptor potential (TRP) channels have emerged as potential sensors and transducers of inflammatory pain. The aims of this study were to investigate (1) the expression of TRP channels in intervertebral disc (IVD) cells in normal and inflammatory conditions and (2) the function of Transient receptor potential ankyrin 1 (TRPA1) and Transient receptor potential vanilloid 1 (TRPV1) in IVD inflammation and matrix homeostasis. RT-qPCR was used to analyze human fetal, healthy, and degenerated IVD tissues for the gene expression of TRPA1 and TRPV1. The primary IVD cell cultures were stimulated with either interleukin-1 beta (IL-1ß) or tumor necrosis factor alpha (TNF-α) alone or in combination with TRPA1/V1 agonist allyl isothiocyanate (AITC, 3 and 10 µM), followed by analysis of calcium flux and the expression of inflammation mediators (RT-qPCR/ELISA) and matrix constituents (RT-qPCR). The matrix structure and composition in caudal motion segments from TRPA1 and TRPV1 wild-type (WT) and knock-out (KO) mice was visualized by FAST staining. Gene expression of other TRP channels (A1, C1, C3, C6, V1, V2, V4, V6, M2, M7, M8) was also tested in cytokine-treated cells. TRPA1 was expressed in fetal IVD cells, 20% of degenerated IVDs, but not in healthy mature IVDs. TRPA1 expression was not detectable in untreated cells and it increased upon cytokine treatment, while TRPV1 was expressed and concomitantly reduced. In inflamed IVD cells, 10 µM AITC activated calcium flux, induced gene expression of IL-8, and reduced disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5) and collagen 1A1, possibly via upregulated TRPA1. TRPA1 KO in mice was associated with signs of degeneration in the nucleus pulposus and the vertebral growth plate, whereas TRPV1 KO did not show profound changes. Cytokine treatment also affected the gene expression of TRPV2 (increase), TRPV4 (increase), and TRPC6 (decrease). TRPA1 might be expressed in developing IVD, downregulated during its maturation, and upregulated again in degenerative disc disease, participating in matrix homeostasis. However, follow-up studies with larger sample sizes are needed to fully elucidate the role of TRPA1 and other TRP channels in degenerative disc disease.

Inflammaging in cervical and lumbar degenerated intervertebral discs: analysis of proinflammatory cytokine and TRP channel expression.

PURPOSE: To investigate and compare the occurrence of inflammatory processes in the sites of disc degeneration in the lumbar and cervical spine by a gene array and subsequent qPCR and to investigate the mechanistic involvement of transient receptor potential channels TRPC6 and TRPV4. METHODS: The gene expression of inflammatory cytokines and TRP channels was measured in human disc samples obtained from patients undergoing discectomy at the cervical (n = 24) or lumbar (n = 27) spine for degenerative disc disease (DDD) and disc herniation (DH) and analyzed for differences with regard to spinal level, IVD degeneration grade, Modic grade, age, sex, disc region and surgical extent. RESULTS: Aside from genes with known implication in DDD and DH, four previously unreported genes from the interferon and TRP families (IFNA1, IFNA8, IFNB1, TRPC6) could be detected. A correlation between gene expression and age (IL-15) and IVD degeneration grade (IFNA1, IL-6, IL-15, TRPC6), but not Modic grade, was identified. Significant differences were detected between cervical and lumbar discs (IL-15), nucleus and annulus (IL-6, TNF-α, TRPC6), single-level and multi-level surgery (IL-6, IL-8) as well as DDD and DH (IL-8), while sex had no effect. Multiple gene-gene pair correlations, either between different cytokines or between cytokines and TRP channels, exist in the disc. CONCLUSION: This study supports the relevance of IL-6 and IL-8 in disc diseases, but furthermore points toward a possible pathological role of IL-15 and type I interferons, as well as a mechanistic role of TRPC6. With limited differences in the inflammatory profile of cervical and lumbar discs, novel anti-inflammatory or TRP-modulatory strategies for the treatment of disc pathologies may be applicable independent of the spinal region.

TRPC6 in simulated microgravity of intervertebral disc cells.

PURPOSE: Prolonged bed rest and microgravity in space cause intervertebral disc (IVD) degeneration. However, the underlying molecular mechanisms are not completely understood. Transient receptor potential canonical (TRPC) channels are implicated in mechanosensing of several tissues, but are poorly explored in IVDs. METHODS: Primary human IVD cells from surgical biopsies composed of both annulus fibrosus and nucleus pulposus (passage 1-2) were exposed to simulated microgravity and to the TRPC channel inhibitor SKF-96365 (SKF) for up to 5 days. Proliferative capacity, cell cycle distribution, senescence and TRPC channel expression were analyzed. RESULTS: Both simulated microgravity and TRPC channel antagonism reduced the proliferative capacity of IVD cells and induced senescence. While significant changes in cell cycle distributions (reduction in G1 and accumulation in G2/M) were observed upon SKF treatment, the effect was small upon 3 days of simulated microgravity. Finally, downregulation of TRPC6 was shown under simulated microgravity. CONCLUSIONS: Simulated microgravity and TRPC channel inhibition both led to reduced proliferation and increased senescence. Furthermore, simulated microgravity reduced TRPC6 expression. IVD cell senescence and mechanotransduction may hence potentially be regulated by TRPC6 expression. This study thus reveals promising targets for future studies. These slides can be retrieved under Electronic Supplementary Material.

Transient receptor potential vanilloid 2-mediated shear-stress responses in C2C12 myoblasts are regulated by serum and extracellular matrix.

The developmental sensitivity of skeletal muscle to mechanical forces is unparalleled in other tissues. Calcium entry via reputedly mechanosensitive transient receptor potential (TRP) channel classes has been shown to play an essential role in both the early proliferative stage and subsequent differentiation of skeletal muscle myoblasts, particularly TRP canonical (TRPC) 1 and TRP vanilloid (TRPV) 2. Here we show that C2C12 murine myoblasts respond to fluid flow-induced shear stress with increments in cytosolic calcium that are largely initiated by the mechanosensitive opening of TRPV2 channels. Response to fluid flow was augmented by growth in low extracellular serum concentration (5 vs. 20% fetal bovine serum) by greater than 9-fold and at 18 h in culture, coincident with the greatest TRPV2 channel expression under identical conditions (P < 0.02). Fluid flow responses were also enhanced by substrate functionalization with laminin, rather than with fibronectin, agreeing with previous findings that the gating of TRPV2 is facilitated by laminin. Fluid flow-induced calcium increments were blocked by ruthenium red (27%) and SKF-96365 (38%), whereas they were unaltered by 2-aminoethoxydiphenyl borate, further corroborating that TRPV2 channels play a predominant role in fluid flow mechanosensitivity over that of TRPC1 and TRP melastatin (TRPM) 7.

An Inflammatory Nucleus Pulposus Tissue Culture Model to Test Molecular Regenerative Therapies: Validation with Epigallocatechin 3-Gallate.

Organ cultures are practical tools to investigate regenerative strategies for the intervertebral disc. However, most existing organ culture systems induce severe tissue degradation with only limited representation of the in vivo processes. The objective of this study was to develop a space- and cost-efficient tissue culture model, which represents degenerative processes of the nucleus pulposus (NP). Intact bovine NPs were cultured in a previously developed system using Dyneema jackets. Degenerative changes in the NP tissue were induced either by the direct injection of chondroitinase ABC (1-20 U/mL) or by the diffusion of interleukin-1 beta (IL-1ß) and tumor necrosis factor alpha (TNF-α) (both 100 ng/mL) from the culture media. Extracellular matrix composition (collagens, proteoglycans, water, and DNA) and the expression of inflammatory and catabolic genes were analyzed. The anti-inflammatory and anti-catabolic compound epigallocatechin 3-gallate (EGCG, 10 µM) was employed to assess the relevance of the degenerative NP model. Although a single injection of chondroitinase ABC reduced the proteoglycan content in the NPs, it did not activate cellular responses. On the other hand, IL-1ß and TNF-α significantly increased the mRNA expression of inflammatory mediators IL-6, IL-8, inducible nitric oxide synthase (iNOS), prostaglandin-endoperoxide synthase 2 (PTGS2) and matrix metalloproteinases (MMP1, MMP3, and MMP13). The cytokine-induced gene expression in the NPs was ameliorated with EGCG. This study provides a proof of concept that inflammatory NP cultures, with appropriate containment, can be useful for the discovery and evaluation of molecular therapeutic strategies against early degenerative disc disease.

Chondrogenic Priming at Reduced Cell Density Enhances Cartilage Adhesion of Equine Allogeneic MSCs - a Loading Sensitive Phenomenon in an Organ Culture Study with 180 Explants.

BACKGROUND: Clinical results of regenerative treatments for osteoarthritis are becoming increasingly significant. However, several questions remain UNANSWERED concerning mesenchymal stem cell (MSC) adhesion and incorporation into cartilage. METHODS: To this end, peripheral blood (PB) MSCs were chondrogenically induced and/or stimulated with pulsed electromagnetic fields (PEMFs) for a brief period of time just sufficient to prime differentiation. In an organ culture study, PKH26 labelled MSCs were added at two different cell densities (0.5 x106 vs 1.0 x106). In total, 180 explants of six horses (30 per horse) were divided into five groups: no lesion (i), lesion alone (ii), lesion with naïve MSCs (iii), lesion with chondrogenically-induced MSCs (iv) and lesion with chondrogenically-induced and PEMF-stimulated MSCs (v). Half of the explants were mechanically loaded and compared with the unloaded equivalents. Within each circumstance, six explants were histologically evaluated at different time points (day 1, 5 and 14). RESULTS: COMP expression was selectively increased by chondrogenic induction (p = 0.0488). PEMF stimulation (1mT for 10 minutes) further augmented COL II expression over induced values (p = 0.0405). On the other hand, MSC markers remained constant over time after induction, indicating a largely predifferentiated state. In the unloaded group, MSCs adhered to the surface in 92.6% of the explants and penetrated into 40.7% of the lesions. On the other hand, physiological loading significantly reduced surface adherence (1.9%) and lesion filling (3.7%) in all the different conditions (p < 0.0001). Remarkably, homogenous cell distribution was characteristic for chondrogenic induced MSCs (+/- PEMFs), whereas clump formation occurred in 39% of uninduced MSC treated cartilage explants. Finally, unloaded explants seeded with a moderately low density of MSCs exhibited greater lesion filling (p = 0.0022) and surface adherence (p = 0.0161) than explants seeded with higher densities of MSCs. In all cases, the overall amount of lesion filling decreased from day 5 to 14 (p = 0.0156). CONCLUSION: The present study demonstrates that primed chondrogenic induction of MSCs at a lower cell density without loading results in significantly enhanced and homogenous MSC adhesion and incorporation into equine cartilage.

Activation of intervertebral disc cells by co-culture with notochordal cells, conditioned medium and hypoxia.

BACKGROUND: Notochordal cells (NC) remain in the focus of research for regenerative therapy for the degenerated intervertebral disc (IVD) due to their progenitor status. Recent findings suggested their regenerative action on more mature disc cells, presumably by the secretion of specific factors, which has been described as notochordal cell conditioned medium (NCCM). The aim of this study was to determine NC culture conditions (2D/3D, fetal calf serum, oxygen level) that lead to significant IVD cell activation in an indirect co-culture system under normoxia and hypoxia (2% oxygen). METHODS: Porcine NC was kept in 2D monolayer and in 3D alginate bead culture to identify a suitable culture system for these cells. To test stimulating effects of NC, co-cultures of NC and bovine derived coccygeal IVD cells were conducted in a 1:1 ratio with no direct cell contact between NC and bovine nucleus pulposus cell (NPC) or annulus fibrosus cells (AFC) in 3D alginate beads under normoxia and hypoxia (2%) for 7 and 14 days. As a positive control, NPC and AFC were stimulated with NC-derived conditioned medium (NCCM). Cell activity, glycosaminoglycan (GAG) content, DNA content and relative gene expression was measured. Mass spectrometry analysis of the NCCM was conducted. RESULTS: We provide evidence by flow cytometry that monolayer culture is not favorable for NC culture with respect to maintaining NC phenotype. In 3D alginate culture, NC activated NPC either in indirect co-culture or by addition of NCCM as indicated by the gene expression ratio of aggrecan/collagen type 2. This effect was strongest with 10% fetal calf serum and under hypoxia. Conversely, AFC seemed unresponsive to co-culture with pNC or to the NCCM. Further, the results showed that hypoxia led to decelerated metabolic activity, but did not lead to a significant change in the GAG/DNA ratio. Mass spectrometry identified connective tissue growth factor (CTGF, syn. CCN2) in the NCCM. CONCLUSIONS: Our results confirm the requirement to culture NC in 3D to best maintain their phenotype, preferentially in hypoxia and with the supplementation of FCS in the culture media. Despite these advancements, the ideal culture condition remains to be identified.

The influence of physical and spatial substrate characteristics on endothelial cells.

Cardiovascular diseases are a main cause of death worldwide, leading to a growing demand for medical devices to treat this patient group. Central to the engineering of such devices is a good understanding of the biology and physics of cell-surface interactions. In existing blood-contacting devices, such as vascular grafts, the interaction between blood, cells, and material is one of the main limiting factors for their long-term durability. An improved understanding of the material's chemical- and physical properties as well as its structure all play a role in how endothelial cells interact with the material surface. This review provides an overview of how different surface structures influence endothelial cell responses and what is currently known about the underlying mechanisms that guide this behavior. The structures reviewed include decellularized matrices, electrospun fibers, pillars, pits, and grated surfaces.

Sulfated Hydrogels as Primary Intervertebral Disc Cell Culture Systems.

The negatively charged extracellular matrix plays a vital role in intervertebral disc tissues, providing specific cues for cell maintenance and tissue hydration. Unfortunately, suitable biomimetics for intervertebral disc regeneration are lacking. Here, sulfated alginate was investigated as a 3D culture material due to its similarity to the charged matrix of the intervertebral disc. Precursor solutions of standard alginate, or alginate with 0.1% or 0.2% degrees of sulfation, were mixed with primary human nucleus pulposus cells, cast, and cultured for 14 days. A 0.2% degree of sulfation resulted in significantly decreased cell density and viability after 7 days of culture. Furthermore, a sulfation-dependent decrease in DNA content and metabolic activity was evident after 14 days. Interestingly, no significant differences in cell density and viability were observed between surface and core regions for sulfated alginate, unlike in standard alginate, where the cell number was significantly higher in the core than in the surface region. Due to low cell numbers, phenotypic evaluation was not achieved in sulfated alginate biomaterial. Overall, standard alginate supported human NP cell growth and viability superior to sulfated alginate; however, future research on phenotypic properties is required to decipher the biological properties of sulfated alginate in intervertebral disc cells.

Exploring the Impact of TLR-2 Signaling on miRNA Dysregulation in Intervertebral Disc Degeneration.

Toll-like receptors (TLRs) are key mediators of inflammation in intervertebral disc (IVD) degeneration. TLR-2 activation contributes to the degenerative process by increasing the expression of extracellular matrix-degrading enzymes, pro-inflammatory cytokines, and neurotrophins. As potent post-transcriptional regulators, microRNAs can modulate intracellular mechanisms, and their dysregulation is known to contribute to numerous pathologies. This study aims to investigate the impact of TLR-2 signaling on miRNA dysregulation in the context of IVD degeneration. Small-RNA sequencing of degenerated IVD cells shows the dysregulation of ten miRNAs following TLR-2 activation by PAM2CSK4. The miR-155-5p is most significantly upregulated in degenerated and non-degenerated annulus fibrosus and nucleus pulposus cells. Sequence-based target and pathway prediction shows the involvement of miR-155-5p in inflammation- and cell fate-related pathways and TLR-2-induced miR-155-5p expression leads to the downregulation of its target c-FOS. Furthermore, changes specific to the activation of TLR-2 through fragmented fibronectin are seen in miR-484 and miR-487. Lastly, miR-100-3p, miR-320b, and miR-181a-3p expression exhibit degeneration-dependent changes. These results show that TLR-2 signaling leads to the dysregulation of miRNAs in IVD cells as well as their possible downstream effects on inflammation and degeneration. The identified miRNAs provide important opportunities as potential therapeutic targets for IVD degeneration and low back pain.

Aloe vera-based biomaterial ink for 3D bioprinting of wound dressing constructs.

This study emphasizes the development of a multifunctional biomaterial ink for wound healing constructs. The biomaterial ink benefits from Aloe vera's intrinsic biocompatible, biodegradable, antioxidant, antimicrobial, anti-inflammatory, and immunomodulatory attributes, thus alleviating the need for supplementary substances employed to combat infections and stimulate tissue regeneration. Moreover, this biomaterial ink seeks to address the scarcity of standardized printable materials possessing adequate biocompatibility and physicochemical properties, which hinder its widespread clinical adoption. The biomaterial ink was synthesized via ionic crosslinking to enhance its rheological and mechanical characteristics. The findings revealed that Aloe vera substantially boosted the hydrogel's viscoelastic behavior, enabling superior compressive modulus and the extrusion of fine filaments. The bioprinted constructs exhibited desirable resolution and mechanical strength while displaying a porous microstructure analogous to the native extracellular matrix. Biological response demonstrated no detrimental impact on stem cell viability upon exposure to the biomaterial ink, as confirmed by live/dead assays. These outcomes validate the potential of the developed biomaterial ink as a resource for the bioprinting of wound dressings that effectively foster cellular proliferation, thereby promoting enhanced wound healing by leveraging Aloe vera's inherent properties.