Objective. Low back pain (LBP) is one of the top three causes of disability in developed countries, and intervertebral disc degeneration (IDD) is a major contributor to LBP. In the process of IDD, there is a gradual decrease in nucleus pulposus cells (NPCs) and extracellular matrix (ECM). Exosomes are important exocrine mediators of stem cells that can act directly on cells for tissue repair and regeneration. In this study, we determined the antisenescence, cell proliferation promotion, and ECM modulation effects of human urine-derived stem cell (USC) exosomes (USC-exos) on degenerated intervertebral discs and explored the underlying mechanism. Methods and Materials. USCs were identified by multipotent differentiation and flow cytometry for mesenchymal stem cell- (MSC-) specific surface protein markers. USC-exos were isolated from the conditioned medium of USCs by ultracentrifugation and then analyzed by transmission electron microscopy (TEM), particle size analysis, and western blotting (WB) for exosome marker proteins. The effects of USC-exos on NPC proliferation and ECM synthesis were assessed by Cell Counting Kit-8 (CCK-8), WB, and immunofluorescence (IF) analyses. The protein differences between normal and degenerative intervertebral discs were mined, and the temporal and spatial variations in matrilin-3 (MATN3) content were determined by WB and IF in the intervertebral disc tissues. The candidate molecules that mediated the function of USC-exos were screened out and confirmed by multiple assays. Meanwhile, the mechanism underlying the candidate protein in USC-exos-induced cell proliferation and regulation of ECM synthesis promoting the activities of NPCs was explored. In addition, the effects of USC-exos on ameliorating intervertebral disc degeneration (IVD) in mice were examined by assessing computed tomography (CT), magnetic resonance imaging (MRI), and histological analyses. Results. The flow cytometry results showed that USCs were positive for CD29, CD44, and CD73, which are USC surface-specific markers, but negative for CD34 and CD45. In addition, USCs showed osteogenic, adipogenic, and chondrogenic differentiation potential. USC-exos exhibited a cup-shaped morphology, with a mean diameter of 49.7 ± 7.3   nm , and were positive for CD63 and TSG101 and negative for calnexin. USC-exos could promote NPC proliferation and ECM synthesis. The protein content of the matrilin family was significantly reduced in degenerative intervertebral discs, and the decrease in MATN3 was the most significant. USC-exos were found to be rich in MATN3 protein, and exosomal MATN3 was required for USC-exos-induced promotion of NPC proliferation and ECM synthesis, as well as alleviation of intervertebral disc degeneration in IVD rats. In addition, the effects of MATN3 in USC-exos were demonstrated to be achieved by activating TGF-β, which elevated the phosphorylation level of SMAD and AKT. Conclusions. Our study suggests that reduced MATN3 can be considered a characteristic of intervertebral disc degeneration. USC-exos may represent a potentially effective agent for alleviating intervertebral disc degeneration by promoting NPC proliferation and ECM synthesis by transferring the MATN3 protein.

Objective. This study is aimed at determining the effects of human urine-derived stem cell-derived exosomes (USCs-exos) on pressure-induced nucleus pulposus cell (NPC) apoptosis and intervertebral disc degeneration (IDD) and on the ERK and AKT signaling pathways. Methods. The NPCs were obtained from patients with herniated lumbar discs. Western blot analysis (WB) and quantitative real-time polymerase chain reaction (qRT-PCR) were used to determine endoplasmic reticulum (ER) stress levels of NPCs under stress. Human USCs were identified using an inverted microscope, three-line differentiation experiments, and flow cytometry. A transmission microscope, nanoparticle size analysis, and WB procedures were used to identify the extracted exosomes and observe NPC uptake. A control group, a 48 h group, and a USCs-exos group were established. The control group was untreated, and the 48 h group was pressure-trained for 48 h, while the USCs-exos group was pressure-trained for 48 h and treated with USCs-exos. WB, qRT-PCR, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis were used to determine the ER stress levels in stress conditions and after exosomal treatment. The AKT and ERK pathways were partially detected. Magnetic Resonance Imaging (MRI) and computed tomography (CT) were used to evaluate cell degeneration while exosomal effects on the intervertebral disc (IVD) tissue were determined by hematoxylin and eosin (HE) staining, Safranin O-fast green staining, immunohistochemical staining (IHC), nuclear magnetic resonance (NMR), spectrometric detection, and total correlation spectroscopy (TOCSY). IVD metabolites were also identified and quantified. Results. After pressure culture, ER stress markers (GRP78 and C/EBP homologous protein (CHOP)) in the NPCs were significantly elevated with time ( p < 0.05 ). Human USCs are short and spindle-shaped. They can successfully undergo osteogenic, adipogenic, and chondrogenic differentiation. In this study, these stem cells were found to be positive for CD29, CD44, and CD73. The exosomes were centrally located with a diameter of 50-100 nm. CD63 and Tsg101 were highly expressed while the expression of Calnexin was suppressed. The exosomes can be ingested by NPCs. USCs-exos significantly improved ER stress responses and inhibited excessive activation of the unfolded protein response (UPR) as well as cell apoptosis and disc degeneration through the AKT and ERK signaling pathways ( p < 0.05 ). Conclusion. Through the AKT and ERK signaling pathways, USCs-exos significantly inhibit ER stress-induced cell apoptosis and IDD under pressure conditions. It is, therefore, a viable therapeutic strategy.

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Purpose: To compare the clinical effects of local anesthesia (LA), general anesthesia (GA) and modified sensation-motion separation anesthesia (MA) in percutaneous endoscopic interlaminar discectomy (PEID) in the treatment of L5/S1 lumbar disc herniation (LDH) for the purpose of guiding junior surgeons. Methods: Eighty-four patients with L5/S1 LDH underwent PEID using three anesthesia methods. Patients in the LA (26), GA (29) and MA (29) groups received a follow-up examination retrospectively. The general parameters, preparation and anesthesia duration, operative duration, recovery time, incidence of complications, ambulation time, length of hospital stay, incidence of severe complications, and reoperation rate were compared, and clinical outcomes were analyzed using a visual analog scale (VAS), the Oswestry Disability Index (ODI), and the Short-Form Health Survey 36 (SF-36). Results: MA demonstrated obvious advantages over the other two methods with respect to operative duration and resulted in a better intraoperative experience than LA. The patients in the MA group required less time in bed postoperatively and shorter hospital stays than those in the GA group. The mean postoperative VAS, ODI and SF-36 scores were significantly better than the preoperative scores in all groups (P<0.05), but no significant differences in these scores were found among the three groups (P>0.05). Three cases (3/29) of nervous disorder occurred in the GA group. Two patients (one in the GA group (1/29) and one in the LA (1/26) group) underwent revision surgery, with a total recurrence rate of 2.4% (2/84). Conclusion: Due to its high safety and good tolerance by patients, MA is a suitable method for spinal surgeons who are inexperienced with PEID in the treatment of L5/S1 disc herniation.

Previous studies have reported that the Ras homolog family member A (RhoA)/myocardin-related transcription factor A (MRTF-A) nuclear translocation axis positively regulates fibrogenesis induced by mechanical forces in various organ systems. The aim of the present study was to determine whether this signaling pathway was involved in the pathogenesis of nucleus pulposus (NP) fibrosis induced by mechanical overload during the progression of intervertebral disc degeneration (IVDD) and to confirm the alleviating effect of an MRTF-A inhibitor in the treatment of IVdd. NP cells (NPcs) were cultured on substrates of different stiffness (2.9 and 41.7 KPa), which mimicked normal and overloaded microenvironments, and were treated with an inhibitor of MRTF-A nuclear import, ccG-1423. In addition, bipedal rats were established by clipping the forelimbs of rats at 1 month and gradually elevating the feeding trough, and in order to establish a long-term overload-induced model of IVdd, and their intervertebral discs were injected with ccG-1423 in situ. cell viability was determined by cell counting Kit-8 assay, and protein expression was determined by western blotting, immunofluorescence and immunohistochemical staining. The results demonstrated that the viability of NPcs was not affected by the application of force or the inhibitor. In NPcs cultured on stiff matrices, MRTF-A was mostly localized in the nucleus, and the expression levels of fibrotic proteins, including type I collagen, connective tissue growth factor and α-smooth muscle cell actin, were upregulated compared with those in NPcs cultured on soft matrices. The levels of these proteins were reduced by ccG-1423 treatment. In rats, 6 months of upright posture activated MRTF-A nuclear-cytoplasmic trafficking and fibrogenesis in the NP and induced IVdd; these effects were alleviated by ccG-1423 treatment. In conclusion, the results of the present study demonstrated that the RhoA/MRTF-A translocation pathway may promote mechanical overload-induced fibrogenic activity in NP tissue and partially elucidated the molecular mechanisms underlying the occurrence of IVdd.