Chen-Hao Zhao

Background Intervertebral disc (IVD) degeneration (IDD) is a leading cause of low back pain, with limited treatment options. The degenerative disc’s harsh microenvironment promotes nucleus pulposus-derived mesenchymal stem cells (NP-MSCs) death and hinders self repair. Mesencephalic astrocyte-derived neurotrophic factor (MANF), an atypical neurotrophic factor, has protective effects in degenerative diseases. However, its role in IDD is unclear. Methods Assessment of MANF expression was conducted in both human nucleus pulposus tissues and a rat IVD puncture model. An in vitro model of degeneration was established by acid treatment of NP-MSCs, and the functional role of MANF was explored through its knockdown and overexpression. RNA sequencing was employed to identify downstream targets. The therapeutic potential of MANF-overexpressing NP-MSCs was evaluated in a rat puncture model. Results MANF expression was markedly downregulated in degenerated IVD tissues from both human patients and rat models. Correspondingly, in vitro experiments demonstrated that MANF knockdown exacerbated, while its overexpression mitigated, acid-induced apoptosis of NP-MSCs. Mechanistically, MANF attenuated mitochondrial dysfunction and ER stress of NP-MSCs under acidic conditions by maintaining MAM integrity, as demonstrated by the complete abolition of this protection upon treatment with the MAM uncoupler FATE1. Transcriptomic analysis and subsequent validation identified receptor expression-enhancing protein 1 (REEP1) as a critical downstream effector through which MANF safeguards MAM integrity. We further elucidated that MANF upregulates REEP1 expression by directly inhibiting miR-33b-5p. In vivo, transplantation of MANF-overexpressing NP-MSCs effectively attenuated IDD in a rat model. Conclusion MANF protected NP-MSCs from acidosis by sustaining MAM integrity via the MiR-33b-5p/REEP1 axis. These findings reveal MANF’s mechanism and therapeutic potential for IDD.

Background: Fibrous scar formation significantly inhibits axonal regeneration and functional recovery following spinal cord injury (SCI). Atractylodin (ATD), an active constituent of traditional Chinese medicine, exhibits broad pharmacological properties, including anti-inflammatory and anti-fibrotic effects. Nevertheless, the potential therapeutic role of ATD in SCI and its underlying molecular mechanisms remain to be fully elucidated. Methods: An SCI model was established in C57 mice. Motor function was assessed using the Basso Mouse Scale scoring system, inclined plane test, swimming test, and footprint analysis. Immunohistochemical staining was performed to evaluate fibrotic scar formation and neuronal survival. Western blotting and quantitative real-time PCR (qPCR) were also employed to investigate the molecular mechanisms underlying ATD-mediated regulation of fibroblasts following SCI. Results: ATD administration significantly enhanced motor function in SCI mice, reduced the area of fibrotic scars, and suppressed the expression of fibrotic markers. Mechanistically, ATD inhibited Mothers Against Decapentaplegic Homolog 2/3 (SMAD2/3) phosphorylation and nuclear translocation, thereby suppressing fibroblast activation and extracellular matrix deposition, while promoting neuronal survival and axonal regeneration. Conclusions: ATD mitigates fibrotic scar formation by targeting the Transforming Growth Factor Beta (TGF-β)/SMAD pathway, thereby facilitating axonal regeneration and functional recovery. This offers a promising therapeutic strategy for SCI.

Loss of nucleus pulposus (NP) cells is as one of the primary factors initiating intervertebral disc (IVD) degeneration (IVDD); however, the intrinsic physiological mechanisms of endogenous NP-derived stem cell (NPSC)-based therapy in IVDD remain poorly understood. Disturbed iron homeostasis is commonly observed in degenerative diseases, and an acidic microenvironment has been considered a crucial factor in IVDD. The molecular mechanism of ferroptosis in acidic microenvironments during IVDD has not been reported. Herein, we intended to investigate whether acidic conditions can induce ferroptosis in NPSCs and explore the mechanism of IVDD progression through NCOA4-mediated ferritinophagy, which is a type of selective autophagy mediating ferroptosis. The role of ring-box 1 (RBX1) in NCOA4-mediated ferritinophagy in NPSC ferroptosis and IVDD pathogenesis was also explored. First, clinical epidemiology research revealed that a reduction in serum ferritin level was an independent risk factor for IVDD. We then demonstrated that ferroptosis progressively increased in human NP tissues as IVDD advanced and the acidic conditions induced ferroptosis-associated decline in cell viability, reactive oxygen species accumulation, and extracellular matrix degradation in human NPSCs. In an acidic microenvironment, ferroptosis is promoted due to enhanced NCOA4-mediated ferritinophagy in NPSCs. A mechanistic study demonstrated that RBX1-mediated ubiquitination modulated NCOA4 expression and the inhibition of RBX1 promoted ferroptosis through NCOA4-mediated ferritinophagy in the human NPSCs. Our in vivo study further illustrated that RBX1 overexpression ameliorated ferroptotic effects on IVDD progression by suppressing NCOA4-mediated ferritinophagy. Results demonstrated the modulating role of RBX1 in NCOA4-mediated ferritinophagy and NPSC ferroptosis, providing valuable insights into the potential application of endogenous stem cell–based IVD self-repair and self-regeneration for IVDD treatment.

Background C1 transpedicular screw (C1TS) placement provided satisfactory pullout resistance and 3D stability, but its application might be limited in patients with basilar invagination (BI) due to the high incidences of the atlas anomaly and vertebral artery (VA) variation. However, no study has explored the classifications of C1 posterior arch variations and investigated their indications and ideal insertion trajectories for C1TS in BI. Purpose To investigate the bony and surrounding arterial characteristics of the atlas, classify posterior arch variations, identify indications for C1TS, evaluate ideal insertion trajectories for C1TS in BI patients without atlas occipitalization (AO), and compare them with those without BI and AO as control. Methods A total of 130 non-AO patients with and without BI (52 patients and 78 patients, respectively) from two medical centers were included at a 1:1.5 ratio. The posterior arch variations were assessed using a modified C1 morphological classification. Comparisons regarding the bony and surrounding arterial characteristics, morphological classification distributions, and ideal insertion trajectories between BI and control groups were performed. The subgroup analyses based on different morphological classifications were also conducted. In addition, the factors possibly affecting the insertion parameters were investigated using multiple linear regression analyses. Results The BI group was associated with significantly smaller lateral mass height and width, sagittal length of posterior arch, pedicle height, vertical height of posterior arch, and distance between VA and VA groove (VAG) than control group. Four types of posterior arch variations with indications for different screw placement techniques were classified; Classifications I and II were suitable for C1TS. The BI cohort showed a significantly lower rate of Classification I than the control cohort. In the BI group, the subgroup of Classification I had significantly larger distance between the insertion point (IP) and inferior aspect of the posterior arch. In addition, it had the narrowest width along ideal screw trajectory, but a significantly more lateral ideal mediolateral angle than the subgroup of Classification II. Multiple linear regression indicated that the cephalad angle was significantly associated with the diagnosis of BI (B = 3.708, P < 0.001) and sagittal diameter of C1 (B = 3.417, P = 0.027); the ideal mediolateral angle was significantly associated with BMI (B = 0.264, P = 0.031), sagittal diameter of C1 (B = − 4.559, P = 0.002), and pedicle height (B = − 2.317, P < 0.001); the distance between the IP and inferior aspects of posterior arch was significantly associated with age (B = − 0.002, P = 0.035), BMI (B = − 0.007, P = 0.028), sagittal length of posterior arch (B = − 0.187, P = 0.032), pedicle height (B = − 0.392, P < 0.001), and middle and lower parts of posterior arch (B = 0.862, P < 0.001). Conclusion The incidence of posterior arch variation in BI patients without AO was remarkably higher than that in control patients. The insertion parameters of posterior screws were different between the morphological classification types in BI and control groups. The distance between VA V3 segments and VAG in BI cohort was substantially smaller than that in control cohort. Preoperative individual 3D computed tomography (CT), CT angiography and intraoperative navigation are recommended for BI patients receiving posterior screw placement.