Advancing skeletal health and disease research with single-cell RNA sequencing.

Orthopedic conditions have emerged as global health concerns, impacting approximately 1.7 billion individuals worldwide. However, the limited understanding of the underlying pathological processes at the cellular and molecular level has hindered the development of comprehensive treatment options for these disorders. The advent of single-cell RNA sequencing (scRNA-seq) technology has revolutionized biomedical research by enabling detailed examination of cellular and molecular diversity. Nevertheless, investigating mechanisms at the single-cell level in highly mineralized skeletal tissue poses technical challenges. In this comprehensive review, we present a streamlined approach to obtaining high-quality single cells from skeletal tissue and provide an overview of existing scRNA-seq technologies employed in skeletal studies along with practical bioinformatic analysis pipelines. By utilizing these methodologies, crucial insights into the developmental dynamics, maintenance of homeostasis, and pathological processes involved in spine, joint, bone, muscle, and tendon disorders have been uncovered. Specifically focusing on the joint diseases of degenerative disc disease, osteoarthritis, and rheumatoid arthritis using scRNA-seq has provided novel insights and a more nuanced comprehension. These findings have paved the way for discovering novel therapeutic targets that offer potential benefits to patients suffering from diverse skeletal disorders.

Collagen biomaterials promote the regenerative repair of abdominal wall defects in Bama miniature pigs.

Due to adhesion and rejection of recent traditional materials, it is still challenging to promote the regenerative repair of abdominal wall defects caused by different hernias or severe trauma. However, biomaterials with a high biocompatibility and low immunogenicity have exhibited great potential in the regeneration of abdominal muscle tissue. Previously, we have designed a biological collagen scaffold material combined with growth factor, which enables a fusion protein-collagen binding domain (CBD)-basic fibroblast growth factor (bFGF) to bind and release specifically. Though experiments in rodent animals have indicated the regeneration function of CBD-bFGF modified biological collagen scaffolds, its translational properties in large animals or humans are still in need of solid evidence. In this study, the abdominal wall defect model of Bama miniature pigs was established by artificial operations, and the defective abdominal wall was sealed with or without a polypropylene patch, and unmodified and CBD-bFGF modified biological collagen scaffolds. Results showed that a recurrent abdominal hernia was observed in the defect control group (without the use of mesh). Although the polypropylene patch can repair the abdominal wall defect, it also induced serious adhesion and inflammation. Meanwhile, both kinds of collagen biomaterials exhibited positive effects in repairing abdominal wall defects and reducing regional adhesion and inflammation. However, CBD-bFGF-modified collagen biomaterials failed to induce the regenerative repair reported in rat experiments. In addition, unmodified collagen biomaterials induced abdominal wall muscle regeneration rather than fibrotic repair. These results indicated that the unmodified collagen biomaterials are a better option among translational patches for the treatment of abdominal wall defects.

Spatially multicellular variability of intervertebral disc degeneration by comparative single-cell analysis.

Previous studies have revealed cellular heterogeneity in intervertebral discs (IVDs). However, the cellular and molecular alteration patterns of cell populations during degenerative progression remain to be fully elucidated. To illustrate the cellular and molecular alteration of cell populations in intervertebral disc degeneration (IDD), we perform single cell RNA sequencing on cells from four anatomic sites of healthy and degenerative goat IVDs. EGLN3+ StressCs, TGFBR3+ HomCs and GPRC5A+ RegCs exhibit the characteristics associated with resistance to stress, maintaining homeostasis and repairing, respectively. The frequencies and signatures of these cell clusters fluctuate with IDD. Notably, the chondrogenic differentiation programme of PROCR+ progenitor cells is altered by IDD, while notochord cells turn to stemness exhaustion. In addition, we characterise CAV1+ endothelial cells that communicate with chondrocytes through multiple signalling pathways in degenerative IVDs. Our comprehensive analysis identifies the variability of key cell clusters and critical regulatory networks responding to IDD, which will facilitate in-depth investigation of therapeutic strategies for IDD.

Reversed windshield-wiper effect leads to failure of cement-augmented pedicle screw: Biomechanical mechanism analysis by finite element experiment.

The failure mode of cement-augmented pedicle screw (CAPS) was different from common pedicle screw. No biomechanical study of this failure mode named as "reversed windshield-wiper effect" was reported. To investigate the mechanisms underlying this failure mode, a series of finite element models of CAPS and PS were modified on L4 osseous model. Nine models were created according to the cement volume at 0.5 mL interval (range: 1-5 mL). Pullout load and cranio-caudal loads were applied on the screws. Stress and instantaneous rotation center (IRC) of the vertebra were observed. Under cranio-caudal load, the stress concentrated on the screw tip and pedicle region. The maximal stress (MS) at the screw tip region was +2.143 MPa higher than pedicle region. With cement volume increasing, the maximal stress (MS) at the screw tip region decreased dramatically, while MS at pedicle region was not obviously affected. As dose increased to 1.5 mL, the MS at pedicle region became higher than screw tip region and the maximal stress difference was observed at 3.5 mL. IRC of the vertebra located at the facet joint region in PS model. While IRC in CAPS models shifted anteriorly closer to the vertebral body with the increasing of cement volume. Under axial pull-out load, the maximal stress (MS) of cancellous bone in CAPS models was 29.53-50.04% lower than that 2.228 MPa in PS model. MS in the screw-bone interface did not change significantly with cement volume increasing. Therefore, the possible mechanism is that anterior shift of IRC and the negative difference value of MS between screw tip and pedicle region due to cement augmentation, leading to the screw rotate around the cement-screw complex as the fulcrum point.

Spatially defined single-cell transcriptional profiling characterizes diverse chondrocyte subtypes and nucleus pulposus progenitors in human intervertebral discs.

A comprehensive understanding of the cellular heterogeneity and molecular mechanisms underlying the development, homeostasis, and disease of human intervertebral disks (IVDs) remains challenging. Here, the transcriptomic landscape of 108 108 IVD cells was mapped using single-cell RNA sequencing of three main compartments from young and adult healthy IVDs, including the nucleus pulposus (NP), annulus fibrosus, and cartilage endplate (CEP). The chondrocyte subclusters were classified based on their potential regulatory, homeostatic, and effector functions in extracellular matrix (ECM) homeostasis. Notably, in the NP, a PROCR+ resident progenitor population showed enriched colony-forming unit-fibroblast (CFU-F) activity and trilineage differentiation capacity. Finally, intercellular crosstalk based on signaling network analysis uncovered that the PDGF and TGF-ß cascades are important cues in the NP microenvironment. In conclusion, a single-cell transcriptomic atlas that resolves spatially regulated cellular heterogeneity together with the critical signaling that underlies homeostasis will help to establish new therapeutic strategies for IVD degeneration in the clinic.

Pharmaceutical targeting of succinate dehydrogenase in fibroblasts controls bleomycin-induced lung fibrosis.

Idiopathic pulmonary fibrosis (IPF) is characterized by excessive deposition of extracellular matrix in the lung with fibroblast-to-myofibroblast transition, leading to chronically compromising lung function and death. However, very little is known about the metabolic alterations of fibroblasts in IPF, and there is still a lack of pharmaceutical agents to target the metabolic dysregulation. Here we show a glycolysis upregulation and fatty acid oxidation (FAO) downregulation in fibroblasts from fibrotic lung, and perturbation of glycolysis and FAO affects fibroblasts transdifferentiation. In addition, there is a significant accumulation of succinate both in fibrotic lung tissues and myofibroblasts, where succinate dehydrogenase (SDH) operates in reverse by reducing fumarate to succinate. Then succinate contributes to glycolysis upregulation and FAO downregulation by stabilizing HIF-1α, which promotes the development of lung fibrosis. In addition, we identify a near-infrared small molecule dye, IR-780, as a targeting agent which stimulates mild inhibition of succinate dehydrogenase subunit A (SDHA) in fibroblasts, and which inhibits TGF-ß1 induced SDH and succinate elevation, then to prevent fibrosis formation and respiratory dysfunction. Further, enhanced cell retention of IR-780 is shown to promote severe inhibition of SDHA in myofibroblasts, which may contribute to excessive ROS generation and selectively induces myofibroblasts to apoptosis, and then therapeutically improves established lung fibrosis in vivo. These findings indicate that targeting metabolic dysregulation has significant implications for therapies aimed at lung fibrosis and succinate dehydrogenase is an exciting new therapeutic target to treat IPF.

PC4 serves as a negative regulator of skin wound healing in mice.

BACKGROUND: Human positive cofactor 4 (PC4) was initially characterized as a multifunctional transcriptional cofactor, but its role in skin wound healing is still unclear. The purpose of this study was to explore the role of PC4 in skin wound healing through PC4 knock-in mouse model. METHODS: A PC4 knock-in mouse model (PC4+/+) with a dorsal full-thickness wound was used to investigate the biological functions of PC4 in skin wound healing. Quantitative PCR, Western blot analysis and immunohistochemistry were performed to evaluate the expression of PC4; Sirius red staining and immunofluorescence were performed to explore the change of collagen deposition and angiogenesis. Proliferation and apoptosis were detected using Ki67 staining and TUNEL assay. Primary dermal fibroblasts were isolated from mouse skin to perform cell scratch experiments, cck-8 assay and colony formation assay. RESULTS: The PC4+/+ mice were fertile and did not display overt abnormalities but showed an obvious delay in cutaneous healing of dorsal skin. Histological staining showed insufficient re-epithelialization, decreased angiogenesis and collagen deposition, increased apoptosis and decreased cell proliferation in PC4+/+ skin. Our data also showed decreased migration rate and proliferation ability in cultured primary fibroblasts from PC4+/+ mice in vitro. CONCLUSIONS: This study suggests that PC4 might serve as a negative regulator of skin wound healing in mice.

Metformin mitigates gastrointestinal radiotoxicity and radiosensitises P53 mutation colorectal tumours via optimising autophagy.

BACKGROUND AND PURPOSE: There is an urgent but unmet need for mitigating radiation-induced intestinal toxicity while radio sensitising tumours for abdominal radiotherapy. We aimed to investigate the effects of metformin on radiation-induced intestinal toxicity and radiosensitivity of colorectal tumours. EXPERIMENTAL APPROACH: Acute and chronic histological injuries of the intestine from mice were used to assess radioprotection and IEC-6 cell line was used to investigate the mechanisms in vitro. The fractionated abdominal radiation model of HCT116 and HT29 tumour grafts was used to determine the effects on colorectal cancer. KEY RESULTS: Metformin alleviated radiation-induced acute and chronic intestinal toxicity by optimising mitophagy which was AMPK-dependent. In addition, our data indicated that metformin increased the radiosensitivity of colorectal tumours with P53 mutation both in vitro and in vivo. CONCLUSION AND IMPLICATIONS: Metformin may be a radiotherapy adjuvant agent for colorectal cancers especially those carrying P53 mutation. Our findings provide a new strategy for further precise clinical trials for metformin on radiotherapy.

Fibrogenic fibroblast-selective near-infrared phototherapy to control scarring.

Rationale: Fibroblasts, the predominant cell type responsible for tissue fibrosis, are heterogeneous, and the targeting of unique fibrogenic population of fibroblasts is highly expected. Very recently, elevated glycolysis is demonstrated to play a pivotal role in the determination of fibrogenic phenotype of fibroblasts. However, it is lack of specific strategies for targeting and elimination of such fibrogenic populations. In this study, a novel strategy to use the a near-infrared (NIR) dye IR-780 for the targeting and elimination of a fibrogenic population of glycolytic fibroblasts to control the cutaneous scarring is developed. Methods: The identification and cell properties test of fibrogenic fibroblasts with IR-780 were conducted by using fluorescence activated cell sorting, transplantation experiments, in vivo imaging, RNA sequencing in human cell experiments and mouse and rat wound models. The uptake of IR-780 in fibroblasts mediated by HIF-1α/SLCO2A1 and the metabolic properties of IR-780H fibroblasts were investigated using RNA interference or signaling inhibitors. The fibrogenic fibroblast-selective near-infrared phototherapy of IR-780 were evaluated in human cell experiments and mouse wound models. Results: IR-780 is demonstrated to recognize a unique glycolytic fibroblast lineage, which is responsible for the bulk of connective tissue deposition during cutaneous wound healing and cancer stroma formation. Further results identified that SLCO2A1 is involved in the preferential uptake of IR-780 in fibrogenic fibroblasts, which is regulated by HIF-1α. Moreover, with intrinsic dual phototherapeutic activities, IR-780 significantly diminishes cutaneous scarring through the targeted ablation of the fibrogenic population by photothermal and photodynamic effects. Conclusion: This work provides a unique strategy for the targeted control of tissue scarring by fibrogenic fibroblast-selective near-infrared phototherapy. It is proposed that IR-780 based theranostic methodology holds promise for translational medicine aimed at regulation of fibrogenic behavior.

Cordycepin prevents radiation ulcer by inhibiting cell senescence via NRF2 and AMPK in rodents.

The pathological mechanisms of radiation ulcer remain unsolved and there is currently no effective medicine. Here, we demonstrate that persistent DNA damage foci and cell senescence are involved in radiation ulcer development. Further more, we identify cordycepin, a natural nucleoside analogue, as a potent drug to block radiation ulcer (skin, intestine, tongue) in rats/mice by preventing cell senescence through the increase of NRF2 nuclear expression (the assay used is mainly on skin). Finally, cordycepin is also revealed to activate AMPK by binding with the α1 and γ1 subunit near the autoinhibitory domain of AMPK, then promotes p62-dependent autophagic degradation of Keap1, to induce NRF2 dissociate from Keap1 and translocate to the nucleus. Taken together, our findings identify cordycepin prevents radiation ulcer by inhibiting cell senescence via NRF2 and AMPK in rodents, and activation of AMPK or NRF2 may thus represent therapeutic targets for preventing cell senescence and radiation ulcer.

Photosensitive Hydrogel Creates Favorable Biologic Niches to Promote Spinal Cord Injury Repair.

Photochemistry is considered to be a promising strategy for hydrogels to mimic the complex and dynamic properties of natural extracellular matrix. However, it is seldom applied in 3D tissue engineering and regenerative medicine due to the attenuation of light. In this study, phenyl azide photchemistry and optical fiber technology are first used to localize adhesive protein on the inner surface of the nerve guidance conduit in a 3D hydrogel scaffold. In vitro coculture assay of neural stem cells (NSCs) shows that photoimmobilization of collagen significantly improves the adhesion and survival of NSCs in the conduit, and exhibits synergistic effect with the sustainable release of growth factor. After implantation in transected spinal cord, the optimized hydrogel scaffold is found to improve the locomotion recovery of rats 12 weeks after spinal cord injury (SCI). Histological analysis suggests that the designed hydrogel scaffold provides a favorable biological niche for neuronal regeneration, thus producing directional neuron tissue and promoting the repair of SCI. This study demonstrates a promising hydrogel scaffold for SCI repair and provides the first understanding of the photoimmobilization of adhesive protein in a 3D hydrogel conduit concerning its functions on spinal cord tissue restoration.

Adaptable to Mechanically Stable Hydrogels Based on the Dynamic Covalent Cross-Linking of Thiol-Aldehyde Addition.

We exploit the thiol-aldehyde addition (TAA) reaction to build a dynamic covalent cross-linking (DCC) hydrogel in the physiological-pH environment. Due to the rapid and reversible TAA reaction, the resulting hydrogels are readily adapted for convenient manipulation, for example, free molding, easy injection, and self-healing. Meanwhile, the labile hemithioacetal bonds within the DCC hydrogel can convert to thermodynamically stable bonds via spontaneous thiol transfer reactions, thereby realizing poststabilization as needed. The successful application as a long-term scaffold for repair of barely self-healed bone defect indicated the hydrogels with both adaptability and mechanical stability based on thiol-aldehyde addition reaction is significant for biomedical areas.

Moldable and Removable Wound Dressing Based on Dynamic Covalent Cross-Linking of Thiol-Aldehyde Addition.

The development of a moldable and removable gel technique for wound dressing is becoming highly desirable. Herein, we describe a facile method to generate an adaptable and dissolvable network of PEG-thiols and aldehyde groups in oxidized dextran. The dynamic covalent chemistry of the thiol-aldehyde addition reaction provides hydrogels with typical rheological behavior and thus endows the hydrogels with an excellent adaptability for the initial operation of wound coverage. Upon addition of free thiol compounds, the dynamic covalent cross-linked hydrogels will dissolve via thiol-hemithioacetal exchange reaction. The successful application as a temporary dressing for scalded wounds indicated the hydrogels had both adaptability and dissolvability based on the thiol-aldehyde addition reaction, which is significant for biomedical areas.

Long noncoding RNA OIP5-AS1 causes cisplatin resistance in osteosarcoma through inducing the LPAATß/PI3K/AKT/mTOR signaling pathway by sponging the miR-340-5p.

The abnormal expression of long noncoding RNAs (lncRNAs) plays an important role in the regulation of human cancer progression and drug resistance. The lncRNA OPI5-AS1 is a crucial regulator in some cancers; however, its role in cisplatin resistance of osteosarcoma remains unclear. We found that OIP5-AS1 was significantly upregulated in cisplatin-resistant (CR) osteosarcoma cells MG63-CR and SaOS2-CR compared with the corresponding parental cells. OIP5-AS1 silencing suppressed cell growth in vitro and in vivo, and promoted apoptosis of MG63-CR and SaOS2-CR cells, indicating that knockdown of OIP5-AS1 significantly decreased cisplatin resistance in MG63-CR and SaOS2-CR cells. This conclusion was supported by the decreased expression of the drug resistance-related factors multidrug resistance-associated protein 1 (MRP1) and P-glycoprotein (P-gp) upon OIP5-AS1 silencing. In addition, OIP5-AS1 downregulation suppressed the PI3K/AKT/mTOR signaling pathway. Importantly, we demonstrated that OIP5-AS1 functions as a competing endogenous RNA of miR-340-5p and regulates the expression of lysophosphatidic acid acyltransferase (LPAATß), which is a target of miR-340-5p. Moreover, downregulation of miR-340-5p partly reversed the inhibitory effect of OIP5-AS1 knockdown on the PI3K/AKT/mTOR pathway and therefore counteracted cisplatin resistance in MG63-CR and SaOS2-CR cells. In conclusion, OIP5-AS1 causes cisplatin resistance in osteosarcoma through inducing the LPAATß/PI3K/AKT/mTOR signaling pathway by sponging the miR-340-5p. Our results contribute to a better understanding of the function and mechanism of OIP5-AS1 in osteosarcoma cisplatin resistance.

A model for the ethylene-mediated auxin distribution under Cr(VI) stress in Arabidopsis thaliana.

Chromium is one of the top 20 highly toxic heavy metals, which affect agricultural land and economically important crops all over the world. The plant responds to cope with the adverse effects caused by exogenous stimuli. The most important plant's growth, as well as stress response components, are the diverse group of phytohormones. Plant root being the first organ that counters soil contaminant, can be severely damaged. Auxin and ethylene are the most important phytohormones of the root growth and development. It is also reported that auxin is and ethylene play acts synergistically against various abiotic stresses. In a recently published article in Plant, Cell, and Environment we reported that high Cr(VI) levels-induced ethylene mediates auxin distribution. We further reported that Cr(VI)-induced ethylene-mediated auxin is involved in the primary root growth inhibition. In the current, study we proposed a functional model for the Cr(V)-induced ethylene-mediated root growth inhibition by modulating cell cycle and auxin distribution.

An NIR-Fluorophore-Based Therapeutic Endoplasmic Reticulum Stress Inducer.

The endoplasmic reticulum (ER) stress signaling or unfolded protein response (UPR) is a common feature of many human diseases, including cancer. Excessive activation of ER stress directly induces cell death, holding a new promising strategy for the therapeutic intervention of cancer. Current ER-stress-inducing agents mainly target UPR components or proteasomes, which exert limited treatment efficacy and undesired side effects due to unselective ER stress and poor tumor-specific distribution. In this study, a unique near-infrared (NIR) fluorophore, IR-34, is synthesized and identified to selectively and efficiently trigger tumoricidal ER stress by targeting the mitochondrial protein NDUFS1. IR-34 is demonstrated to specifically accumulate in living cancer cells for tumor NIR imaging and drastically inhibit tumor growth and recurrence without causing apparent toxicity. Thus, this multifunctional NIR fluorophore may represent a novel theranostic agent for tumor imaging-guided treatment and also strengthens the idea that mitochondria could be a useful target for therapeutic ER stress in cancer cells.

Low Magnitude of Compression Enhances Biosynthesis of Mesenchymal Stem Cells towards Nucleus Pulposus Cells via the TRPV4-Dependent Pathway.

Mesenchymal stem cell- (MSC-) based therapy is regarded as a promising tissue engineering strategy to achieve nucleus pulposus (NP) regeneration for the treatment of intervertebral disc degeneration (IDD). However, it is still a challenge to promote the biosynthesis of MSC to meet the requirement of NP regeneration. The purpose of this study was to optimize the compressive magnitude to enhance the extracellular matrix (ECM) deposition towards discogenesis of MSCs. Thus, we constructed a 3D culture model for MSCs to bear different magnitudes of compression for 7 days (5%, 10%, and 20% at the frequency of 1.0 Hz for 8 hours/day) using an intelligent and mechanically active bioreactor. Then, the underlying mechanotransduction mechanism of transient receptor potential vanilloid 4 (TRPV4) was further explored. The MSC-encapsulated hybrids were evaluated by Live/Dead staining, biochemical content assay, real-time PCR, Western blot, histological, and immunohistochemical analysis. The results showed that low-magnitude compression promoted anabolic response where high-magnitude compression induced the catabolic response for the 3D-cultured MSCs. The anabolic effect of low-magnitude compression could be inhibited by inhibiting TRPV4. Meanwhile, the activation of TRPV4 enhanced the biosynthesis analogous to low-magnitude compression. These findings demonstrate that low-magnitude compression promoted the anabolic response of ECM deposition towards discogenesis for the 3D-cultured MSCs and the TRPV4 channel plays a key role on mechanical signal transduction for low-magnitude compressive loading. Further understanding of this mechanism may provide insights into the development of new therapies for MSC-based NP regeneration.

Effectiveness of Transpedicular Dynamic Stabilization in Treating Discogenic Low Back Pain.

PURPOSE: To assess clinical outcomes after dynamic stabilization in discogenic low back pain. METHODS: From April 2012 to January 2015, 23 patients with discogenic low back pain were treated with dynamic stabilization via the Wiltse approach. Main clinical assessments included visual analog scale, Oswestry Disability Index, and complications. Radiographs were evaluated for lumbar range of motion and intervertebral height. The Woodend classification was determined by magnetic resonance imaging. RESULTS: There were 23 cases evaluated with a mean follow-up time of 39 months. At last follow-up, visual analog scale and Oswestry Disability Index scores improved significantly compared with preoperatively (P < 0.05). At the stabilized segments, the height of intervertebral discs was increased significantly after surgery (P < 0.05). At last follow-up, the height was reduced to the preoperative level. At the operated segment, 47.4% of the flexion/extension range of motion was retained. Six discs showed rehydration with 1 grade improvement on the Woodend classification. CONCLUSIONS: Dynamic stabilization was a safe and effective treatment in carefully selected groups of patients with discogenic low back pain and promoted disc regeneration to some extent.

N-Cadherin-Mediated Activation of PI3K/Akt-GSK-3ß Signaling Attenuates Nucleus Pulposus Cell Apoptosis Under High-Magnitude Compression.

BACKGROUND/AIMS: Mechanical overloading-induced nucleus pulposus (NP) apoptosis plays an important role in the pathogenesis of intervertebral disc degeneration. N-cadherin (N-CDH)-mediated signaling preserves normal NP cell phenotype. This study aims to investigate the effects of N-CDH on NP cell apoptosis under high-magnitude compression and the underlying mechanism behind this process. METHODS: Rat NP cells seeded on scaffold were perfusion-cultured using a self-developed perfusion bioreactor for 5 days and experienced different magnitudes (2% and 20% compressive deformation, respectively) of compression at a frequency of 1.0 Hz for 4 hours once per day. The un-loaded NP cells were used as controls. Lentivirus-mediated N-CDH overexpression and inhibitor LY294002 were used to further investigate the role of N-CDH and PI3K/Akt pathway under high-magnitude compression, respectively. NP cell apoptosis was evaluated by caspase-3 activity measured using a commercial kit, flow cytometry, and expression of apoptosis-related molecules analyzed by real-time PCR and western blotting assays. RESULTS: High-magnitude compression significantly increased apoptotic NP cells, caspase-3 activity and expression of pro-apoptotic molecules (Bax and caspase-3/cleaved caspase-3), but decreased expression of anti-apoptotic molecule (Bcl-2). High-magnitude compression decreased expression of N-CDH, p-Akt and p-GSK-3ß. However, N-CDH overexpression attenuated NP cell apoptosis and increased expression of p-Akt and p-GSK-3ß under high-magnitude compression. Further analysis showed that inhibition of the PI3K/Akt pathway suppressed NP cell apoptosis and decreased expression of p-GSK-3ß, but had no significant effects on N-CDH expression under high-magnitude compression. CONCLUSION: N-CDH can attenuate NP cell apoptosis through activating the PI3K/Akt-GSK-3ß signaling under high-magnitude compression.