Mitochondrial dysfunction: a new molecular mechanism of intervertebral disc degeneration.

OBJECTIVE: Intervertebral disc degeneration (IVDD) is a chronic degenerative orthopedic illness that causes lower back pain as a typical clinical symptom, severely reducing patients' quality of life and work efficiency, and imposing a significant economic burden on society. IVDD is defined by rapid extracellular matrix breakdown, nucleus pulposus cell loss, and an inflammatory response. It is intimately related to the malfunction or loss of myeloid cells among them. Many mechanisms have been implicated in the development of IVDD, including inflammatory factors, oxidative stress, apoptosis, cellular autophagy, and mitochondrial dysfunction. In recent years, mitochondrial dysfunction has become a hot research topic in age-related diseases. As the main source of adenosine triphosphate (ATP) in myeloid cells, mitochondria are essential for maintaining myeloid cell survival and physiological functions. METHODS: We searched the PUBMED database with the search term "intervertebral disc degeneration and mitochondrial dysfunction" and obtained 82 articles, and after reading the abstracts and eliminating 30 irrelevant articles, we finally obtained 52 usable articles. RESULTS: Through a review of the literature, it was discovered that IVDD and cellular mitochondrial dysfunction are also linked. Mitochondrial dysfunction contributes to the advancement of IVDD by influencing a number of pathophysiologic processes such as mitochondrial fission/fusion, mitochondrial autophagy, cellular senescence, and cell death. CONCLUSION: We examine the molecular mechanisms of IVDD-associated mitochondrial dysfunction and present novel directions for quality management of mitochondrial dysfunction as a treatment approach to IVDD.

Strategies for Cartilage Repair in Osteoarthritis Based on Diverse Mesenchymal Stem Cells-Derived Extracellular Vesicles.

Osteoarthritis (OA) causes disability and significant economic and social burden. Cartilage injury is one of the main pathological features of OA, and is often manifested by excessive chondrocyte death, inflammatory response, abnormal bone metabolism, imbalance of extracellular matrix (ECM) metabolism, and abnormal vascular or nerve growth. Regrettably, due to the avascular nature of cartilage, its capacity to repair is notably limited. Mesenchymal stem cells-derived extracellular vesicles (MSCs-EVs) play a pivotal role in intercellular communication, presenting promising potential not only as early diagnostic biomarkers in OA but also as efficacious therapeutic strategy. MSCs-EVs were confirmed to play a therapeutic role in the pathological process of cartilage injury mentioned above. This paper comprehensively provides the functions and mechanisms of MSCs-EVs in cartilage repair.

Cellular senescence - Molecular mechanisms of intervertebral disc degeneration from an immune perspective.

Intervertebral disc degeneration (IVDD) is a frequent and intractable chronic condition in orthopedics that causes enormous discomfort in patients' lives and thoughts, as well as a significant economic burden on society and the nation. As a result, understanding the pathophysiology of IVDD is critical. The pathophysiology of IVDD has been linked to numerous variables, including oxidative stress, apoptosis, matrix metalloproteinases, and inflammatory factors. Cellular senescence has recently attracted a lot of attention in the study of age-related diseases. It has been discovered that IVDD is intimately linked to human senescence, in which nucleus pulposus cell senescence may play a significant role. Previously, our group did a comprehensive and systematic clarification of the pathogenesis of IVDD from an immune perspective and discovered that the fundamental pathogenesis of IVDD is inflammatory upregulation and nucleus pulposus cell death caused by an imbalance in the immune microenvironment. In this review, we will treat nucleus pulposus cell senescence as a novelty point to clarify the pathophysiology of IVDD and further explore the probable relationship between senescence and immunity along with the dysregulation of the immunological microenvironment to propose new therapeutic approaches for IVDD.

[Effectiveness of proximal femoral nail anti-rotation and cerclage fixation for complicated femoral subtrochanteric fractures].

OBJECTIVE: To investigate the effectiveness of proximal femoral nail anti-rotation (PFNA) and cerclage fixation for complicated femoral subtrochanteric fractures. METHODS: A clinical data of 74 patients with complicated femoral subtrochanteric fractures, who were admitted between March 2016 and March 2019 and met the criteria, was retrospectively analyzed. Among them, 39 patients were treated with limited open reduction and PFNA combined with cerclage fixation (observation group) and 35 patients were treated with closed reduction and PFNA fixation (control group). There was no significant difference in gender, age, cause of injury, side and type of fracture, and the time from injury to operation ( P>0.05). The ratio of postoperative hemoglobin (1, 3, and 5 days) to the preoperative hemoglobin, the operation time, the first weight-bearing time after operation, and the hospital stay were recorded. X-ray films were taken to observe fracture healing in the two groups and bone resorption around the cerclage in the observation group, and the fracture healing time was recorded. Hip function was evaluated by Harris scoring. RESULTS: The operation time of the observation group was significantly longer than that of the control group ( P<0.05), but the first weight-bearing time and hospital stay were significantly shorter ( P<0.05). All patients were followed up 12 months. There was no significant difference in the ratios of post- to pre-operative hemoglobin (1, 3, and 5 days) between the two groups ( P>0.05). X-ray film reexamination showed that the fractures of the two groups healed smoothly, and the fracture healing time of the observation group was significantly shorter than that of the control group ( t=-12.989, P=0.000). No bone resorption around the cerclage occurred in the observation group. The Harris scores of the observation group were better than those of the control group at 7 days and 1, 2, and 3 months after operation ( P<0.05), and there was no significant difference between the two groups at 6 months after operation ( t=1.329, P=0.180). CONCLUSION: Compared with PFNA fixation, PFNA combined with cerclage fixation for the complicated femoral subtrochanteric fractures has a shorter operation time, and can obtain immediate stability after fixation, which can meet the needs of patients for early functional exercise.

Near-infrared light-responsive, pramipexole-loaded biodegradable PLGA microspheres for therapeutic use in Parkinson's disease.

Parkinson's disease (PD) is associated with symptoms such as tremor and bradykinesia which, together with a rigorous dosing regimen, can place an untenable burden on patients. These issues underscore the need for triggerable, modulated drug delivery systems. Currently, pramipexole (PRX) is the most widely used non-ergot dopamine agonist for the treatment of PD. In this study, near-infrared light-responsive PRX and hollow gold nanospheres (HGNS)-loaded biodegradable poly (D, L-lactide-co-glycolide) (PLGA) microspheres (PRX/HGNS MS) were fabricated using solid-in-oil-in-water (S/O/W) and water-in-oil-in-water (W/O/W) emulsion-solvent evaporation techniques to achieve modulated drug release. The PRX/HGNS MS were uniform, with an average diameter of approximately 24 µm, favorable PRX and HGNS encapsulation efficiencies (51.71 ±â€¯0.54% and 65.15 ±â€¯2.30%, respectively) and rapid, controllable drug release both in vitro and in vivo. Cytotoxicity tests revealed no significant differences between HGNS and PRX/HGNS MS when compared with a negative control. Pharmacodynamics and immunohistochemistry studies revealed a more rapid recovery of striatum in the group treated with PRX/HGNS MS produced using the S/O/W method. The results clearly demonstrate that light-responsive PRX/HGNS MS produced using the S/O/W method have the potential to address PD patients' mobility problems in a smart, controllable and remotely triggerable manner.

Highly bioactive, bevacizumab-loaded, sustained-release PLGA/PCADK microspheres for intravitreal therapy in ocular diseases.

Bevacizumab, a vascular endothelial growth factor (VEGF)-targeting drug, is widely used as an off-label therapeutic for age-related macular degeneration (AMD). To reduce the monthly administration frequency, this study investigated microspheres comprising a poly(d, l-lactide-co-glycolide)/poly(cyclohexane-1,4-diyl acetone dimethylene ketal) (PLGA/PCADK) blend that could be loaded with bevacizumab-dextran particles using solid-in-oil-in-water (S/O/W) emulsification. Control microspheres were also prepared through water-in-oil-in-water (W/O/W) emulsification. The structural stability of bevacizumab in the polymer monomers was analyzed using dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), size exclusion chromatography (SEC-HPLC), circular dichroism (CD) and fluorescence spectroscopy. Subsequently, microspheres were prepared and evaluated in terms of their morphology, encapsulation efficiency and release behavior. PLGA/PCADK microspheres prepared by the S/O/W method with <20% PCADK showed a smooth spherical structure with a uniform distribution of bevacizumab. The microspheres exhibited a release behavior comprising a slight initial burst and an increasing total release over 50 days both in vitro and in vivo. Additionally, the microspheres were well tolerated by ocular tissue. Finally, a chorioallantoic membrane (CAM) assay revealed that the bioactivity of bevacizumab was retained by PCADK. In conclusion, these results suggest the potential for bevacizumab-loaded PLGA/PCADK microspheres prepared by the S/O/W method as a means of intravitreal therapy for ocular diseases.

[Mechanism of Duhuo Jisheng decotion in delaying degeneration of nucleus pulposus cells in human intervertebral disc].

This paper aimed to investigate the role of Duhuo Jisheng decotion (DHJSD) in delaying human disc degeneration and its possible molecular mechanism. The intervertebral disc specimens were divided into normal and degenerated groups according to Pfirrmann classfication. The expressions of TNF-α, IL-1ß, MMP-3 and MMP-13 in intervertebral disc tissue were detected by Western blot and PCR. Then degenerated human primary NPCs were cultured in vitro, the viability of NPCs treated with stromal cell-derived factor-1 (SDF-1，10 µg·L⁻¹)and various concentrations of DHJSD was assessed by the CCK-8 assay, and the appropriate concentration was screened. The experiment was divided into three groups, control group, SDF-1 group and DHJSD plus SDF-1 group. The levels of TNF-α, IL-1ß, Agg, coIⅡ, MMP-3 and MMP-13 were detected. The levels of CXCR4, NF-κB major groups P65 phosphorylation (p-P65) and nuclear translocation, after treated with CXCR4 siRNA and NF-κB inhibitor (BAY11-7082) were measured by Western blot and immunofluorescence. At the same time, the expression of cell inflammatory factors and extracellular matrix were also measured. The expressions of TNF-α, IL-1ß, MMP-3 and MMP-13 in the degenerated intervertebral disc tissue were significantly increased. In vitro study, the results of CCK-8 indicated that the viability of NPCs was significantly increased when DHJSD concentration was 300 mg·L⁻¹. After the experiment was divided into three groups, compared with SDF-1 group, the expressions of TNF-α, IL-1ß, MMP-3 and MMP-13 in DHJSD group were significantly decreased, but the expressions of Agg, coIⅡ were significantly increased. When CXCR4-siRNA was transfected into NPCs, SDF-1 increased expressions of CXCR4 and p-P65 and inhibited nuclear translocation of P65, whose effect was suppressed by CXCR4-siRNA and DHJSD. In addition, when BAY11-7082 was used to treat NPCs, the expression of TNF-α, IL-1ß, MMP-3 and MMP-13 were significantly decreased. DHJSD could inhibit the production of inflammatory factors and promote the synthesis of extracellular matrix. The potential mechanism may be related to the SDF-1/CXCR4/NF-κB signaling pathway.

Duhuo Jisheng Decoction inhibits SDF-1-induced inflammation and matrix degradation in human degenerative nucleus pulposus cells in vitro through the CXCR4/NF-κB pathway.

Lower back pain (LBP) is the most common disease in orthopedic clinics world-wide. A classic Fangji of traditional Chinese medicine, Duhuo Jisheng Decoction (DHJSD), has been proven clinically effective for LBP but its therapeutic mechanisms remain unclear. We hypothesized that DHJSD might relieve LBP through inhibiting the exaggerated proinflammatory cytokines and extracellular matrix (ECM) degradation. Thus, we studied the effects of DHJSD on stromal cell-derived factor-1 (SDF-1)-induced inflammation and ECM degradation in human nucleus pulposus cells (hNPCs). The primary hNPCs were isolated from either degenerated human intervertebral disc (HID) of LBP patients or normal HID of lumbar vertebral fracture patients, and cultured in vitro. The cells were treated with SDF-1 (10 ng/mL) and subsequently with different concentrations (100-500 µg/mL) of DHJSD for 24 h, respectively. We found that application of DHJSD significantly antagonized the SDF-1-induced production of proinflammatory cytokines and reduction of aggrecan and type II collagen in the hNPCs. DHJSD also markedly reduced the SDF-1-induced increase of CXCR4 and p-p65 and inhibited the nuclear translocation of p65 in the hNPCs. DHJSD, CXCR4-siRNA, and NF-κB inhibitor (BAY11-7082) caused the same inhibition of exaggerated proinflammatory cytokines in the SDF-1-treated hNPCs. These results provided compelling evidence that DHJSD may inhibit the generation of proinflammatory mediators and ECM degradation of HID through an orchestrated targeting at multiple molecules in the SDF-1/CXCR4/NF-κB pathway, thus offered novel mechanistic insights into the clinical effectiveness of DHJSD on LBP.

[Role and mechanism of stromal cell derived factor 1 on proliferation of vascular endothelial cells].

Objective: To investigate the role and relative mechanism of stromal cell derived factorl (SDF-1) secreted by nucleus pulposus cells (NPCs) on the proliferation of vascular endothelial cells (VECs). Methods: The NPCs were isolated from the degenerated disc specimens after discectomy. NPCs at passage 1 were transfected with lentivirus-mediated SDF-1 over-expression; transfected and untransfected NPCs at passage 2 were cultured in the three-dimensional alvetex® scaffold, then they were co-cultured with HMEC-1 cells. The morphology of NPCs was observed by scanning electron microscope (SEM), and the apoptosis of HMEC-1 cells was detected by Annexin V/propidiumiodide staining after 72 hours co-culutre. The proliferation of HMEC-1 cells was detected by cell counting kit 8 at 12, 24, 48, and 72 hours in transfected group and untransfected group, respectively. ELISA was used to measure the vascular endothelial growth factor (VEGF) expression level. The virus transfection efficiency and relative Akt pathway were determined by Western blot. Results: The NPCs maintained cell phenotype and secreted much extracellular matrix in three-dimensional-culture by SEM observation. In the co-culutre system, after NPCs were transfected with SDF-1 over-expression lentivirus, the proliferation of HMEC-1 cells was significantly increased, while the apoptosis was decreased obviously. The ELISA results demonstrated that the amount of VEGF was remarkably increased in the culture medium. Furthermore, SDF-1 promoted the up-regulation of phosphorylate Akt expression; after inhibition of Akt expression by GSK690693, the proliferation rate of VECs decreased significantly. Conclusion: Over-expression of SDF-1 by NPCs is beneficial for VECs proliferation, which is involved in SDF-1-Akt signalling pathway.