Objective
To summarize the role of cellular senescence and senescent secretary phenotype in the intervertebral disc (IVD) degeneration.
Methods
Relevant articles that discussed the roles of cellular senescence in the IVD degeneration were extensively reviewed, and retrospective and comprehensive analysis was performed. The senescent phenomenon during IVD degeneration, senescent secretary phenotype of the disc cells, senescent pathways within the IVD microenvironment, as well as the anti-senescent approaches for IVD regeneration were systematically reviewed.
Results
During aging and degeneration, IVD cells gradually and/or prematurely undergo senescence by activating p53-p21-retinoblastoma (RB) or p16INK4A-RB senescent pathways. The accumulation of senescent cells not only decreases the self-renewal ability of IVD, but also deteriorates the disc microenvironment by producing more inflammatory cytokines and matrix degrading enzymes. More specific senescent biomarkers are required to fully understand the phenotype change of senescent disc cells during IVD degeneration. Molecular analysis of the senescent disc cells and their intracellular signaling pathways are needed to get a safer and more efficient anti-senescence strategy for IVD regeneration.
Conclusion
Cellular senescence is an important mechanism by which IVD cells decrease viability and degenerate biological behaviors, which provide a new thinking to understand the pathogenesis of IVD degeneration.
Objective To summarize the research progress of platelet-rich plasma (PRP) for the treatment of discogenic low back pain (DLBP). Methods The literature on the treatment of DLBP with PRP was extensively reviewed, and the classification, treatment mechanism, in vitro and in vivo experiments and clinical trial progress of PRP were summarized. Results According to the PRP composition, preparation methods, and physicochemical properties, there are five commonly used PRP classification systems at present. PRP is involved in delaying or reversing the progress of disc degeneration and pain control by promoting the regeneration of nucleus pulposus cells, increasing the synthesis of extracellular matrix, and regulating the internal microenvironment of degenerative intervertebral disc. Although several in vitro and in vivo studies have confirmed that PRP can promote disc regeneration and repair, significantly relieve pain, and even improve the mobility of DLBP patients. But the contrary conclusion has been reached in a few studies, and there are limitations to the application of PRP. ConclusionCurrent studies have confirmed the effectiveness and safety of PRP in the treatment of DLBP and intervertebral disc degeneration, as well as the advantages of PRP in terms of ease of extraction and preparation, low immunological rejection, high regenerative and repair capacity, and the ability to compensate for the shortcomings of traditional treatment modalities. However, relevant studies are still needed to further optimize PRP preparation methods, unify systematic classification guidelines, and clarify its long-term effectiveness.
ObjectiveTo analyze the relationship between the bone mineral density (BMD) and lumbar intervertebral disc degeneration in rhesus macaques by using T1ρ-MRI.
MethodsTwenty female rhesus macaques at the age of 10.9 years on average (rang, 4-20 years) were selected. The lumbar intervertebral discs were classified by Pfirrmann grading system and the T1ρ relaxation time (T1ρ value) was examined by using MRI (Philips 1.5 Tesla), and then BMD values of the L4,5 vertebrae and femoral ward's triangle were detected by using Osteocore dual energy X-ray absorptiometry. Finally, the relationship of T1ρ value of the lumbar intervertebral discs and Pfirrmann grading with age, weight, BMD of lumbar vertebrae and femoral ward's triangle was analyzed.
ResultsThe BMD values of lumbar vertebrae and femoral ward's triangle were (0.64±0.17) g/cm2 and (0.67±0.19) g/cm2 respectively, showing no significant difference (t=2.893, P=0.128). According to Pfirrmann grading system, there were 7 cases of grade I, 8 cases of grade Ⅱ, and 5 cases of grade Ⅲ at L4,5 intervertebral discs. The T1ρ value of the lumbar intervertebral disc was (104.08±18.65) ms; the T1ρ values of grades I, Ⅱ, and Ⅲ were (121.31±13.44), (104.73±15.01), and (77.41±11.87) ms, respectively. There was a negative correlation between T1ρ value and the age and the BMD of lumbar vertebrae and femoral ward's triangle. There was a positive correlation between Pfirrmann grading and the variables as listed above. Significant negative linear correlation was also observed between T1ρ value and Pfirrmann grading.
ConclusionThe T1ρ value is a reliable index when quantifying lumbar intervertebral disc degeneration, and there is a significant positive correlation between BMD and lumbar intervertebral disc degeneration in rhesus macaques.
Objective Polylactic acid (PLA) patch has proper steric configuration, sufficient mechanic strength, and flexibil ity, to investigate the blocking effect on the intra-discal inflammation after annulus puncture sticked by medical glue so as to seal the pinhole left after annulus puncture. Methods Twenty healthy New Zealand white rabbits (weighing 2.0-2.5 kg) were randomly divided into 4 groups (n=5): groups A, B, C, and D. In group A, the rabbits underwent exposure of intervertebral disc and transverse process at L2-7 as a control; in group B, the rabbits received annulus puncture at L2-7 with an 18-gauge needle; and in groups C and D, the pinholes were sealed respectively with a PLA patch sticked with medical gel and medical gel alone after annulus puncture at L2-7. General condition of rabbits was observed after operation. The intervertebral disc tissue was harvested 1 week after operation. The tissue structure was observed by HE and Masson staining. And the expressions of inflammatory factors l ike interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), and inducible nitric oxide synthase (iNOs) were detected with immunohistochemistry and ELISA. Results All the animals survived till the end of the experiment. In group A at 1 week, the nucleus pulposus tissue had normal structure. In group B at 1 week, leak of nucleus pulposus from the pinhole and sl ight adhesion to the adjacent tissue could be seen, and the nucleus pulposus tissue had significant degenerative change by histological observation. In groups C and D, clots of coagulated medical gel and extensive adhesion to the adjacent tissue could be seen; histological observation suggested that the nucleus pulposus tissue of group C had similar histology manifestation to that of group A; while group D had similar histology manifestation to group B with obviously-decreased cells and disorder of matrix. ELISA test showed remarkably elevated expression level of inflammatory factors including IL-1β, TNF-α, and iNOs in groups B and D when compared with groups A and C, showing significant differences (P lt; 0.05), and similar expression level were observed in groups A and C, groups B and D (P gt; 0.05). Conclusion The PLA patch sticked with medical gel is effective in blocking the intra-discal inflammation 1 week after annulus puncture.
Objective To review the research advances in animal models of human disc degeneration. Methods The relative articles in recent years were extensively reviewed. Studies both at home and abroad were analyzed and classified. The advantages and disadvantages of each method were compared. Results Studies were classified as either experimentally induced models or spontaneous models. The induced models were subdivided as mechanical (alteration of forces on the normal disc), structural (injury or chemical alteration) and genetically induced models. Spontaneous models included those animals that naturally developed degenerative disc disease. Conclusion Animal model of intervertebral disc degeneration is an important path for revealing the pathogenesis of human disc degeneration, and play an important role in testing novel interventions. With recent advances in the relevance of animal models and humans, it has a great prospect in study of human disc degeneration.
ObjectiveTo investigate the influence of endoplasmic reticulum stress (ERS) on smoking-induced nucleus pulposus cells apoptosis and inflammatory response.MethodsBetween October 2016 and October 2018, 25 patients with cervical disc herniation receiving discectomy were collected and divided into smoking group (14 cases) and non-smoking group (11 cases). The baseline data of age, gender, herniated segment, and Pfirrmann grading showed no significant difference between the two groups (P>0.05). The obtained nucelus pulposus tissues were harvested to observe the cell apoptosis via detecting the apoptosis-related proteins (Caspase-3 and PRAP) by TUNEL staining and Western blot test. The nucleus pulposus cells were isolated and cultured with enzyme digestion, of which the third generation cells were used in follow-up experiments. Then, the expressions of inflammatory factors [interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α)] were detected by ELISA; the nuclear translocation of P65 was monitored by cell immunofluorescence staining. Furthermore, ERS-related proteins (GRP78 and CHOP) were detected by Western blot; and endoplasmic reticulum ultrastructure was observed under transmission electron microscope. To verify the regulatory effect of ERS, cells were pretreated by ERS specific inhibitor (4-PBA), then cell apoptosis and inflammatory response were tested.ResultsThe nucleus pulposus tissue observation showed that the cell apoptotic rate and the expressions of apoptosis-related proteins (Caspase-3 and PARP) were obviously higher in smoking group than in non-smoking group (P<0.05). The nucleus pulposus cells observation indicated that the expressions of the inflammatory factors (IL-1β and TNF-α) and the ERS-related proteins (GRP78 and CHOP) were also higher in smoking group than in non-smoking group (P<0.05). The results of cell immunofluorescence staining further confirmed that smoking stimulated nuclear translocation of P65 in nucleus pulposus cells. The ERS injury was much more serious in smoking group than in non-smoking group. Furthermore, after 4-PBA inhibiting ERS, the expressions of GRP78, CHOP, IL-1β, TNF-α, and P65 were significantly decreased (P<0.05), and flow cytometry results showed that cell apoptotic rate in smoking group was decreased, showing significant difference compared with the non-smoking group (P<0.05).ConclusionSomking can stimulate cell apoptosis and inflammatory response in nucleus pulposus cells via ESR pathway. Suppressing ESR may be a novel target to suspend smoking-induced intervertebral disc degeneration.
Objective To introduce the research of nucleus pulposus cells for treating intervertebral disc degeneration. Methods The original articles in recent years about nucleus pulposus cells for treating intervertebral disc degeneration were extensively reviewed, and retrospective and comprehensive analysis was performed. Results Nucleus pulposus cells are not only simply a remnant of embryonic notochordal cells, but have also an important influence on the well-being of the whole disc. The biological treatment strategies aim to regenerate the disc by either trying to improve the micro-enviroment within the disc or to increase the popoulation of the nucleus pulposus, which includes transplanting mesenchymal stem cellsto differentiate into nucleus-l ike cells in the degenerated intervertebral disc. Conclusion Nucleus pulposus cells or ucleus pulposus l ike cells based cell transplantation methods prove to be a promising and real istic approach for the intervertebral disc regeneration.
ObjectiveTo investigate the effect of zinc finger protein A20 on lumbar intervertebral disc degeneration in rabbits.MethodsTwenty-six 3-month-old New Zealand rabbits, 2.0-2.5 kg in weight, were used to establish the model of intervertebral disc degeneration at L3, 4, L4, 5, and L5, 6 by transabdominal needle puncture. At 4 weeks after operation, the 24 rabbits were randomly divided into 4 groups after successful modeling, which checked by MRI. The target intervertebral discs of each group were injected with zinc finger protein A20 overexpressed adenovirus (Ov-A20 group), empty carrier adenovirus (NC group), phosphate buffer saline (control group), and shRNA-A20 adenovirus (Sh-A20 group). The biological responses of animals in each group were comprehensive scored before 1 day of injection and after 1, 2, 3, and 6 days of injection. At 2, 4, and 8 weeks after injection, the animals in each group were observed by MRI to obtain the exact T2 relaxation time (T2 signal value). After MRI examination, the animals were killed to take the degenerative intervertebral disc tissue; and the tissue was detected by Alcian blue staining to observed the intervertebral disc degeneration. The expressions of zinc finger protein A20, collagen Ⅱ, and aggrecan were detected by immunohistochemistry staining. The expressions of zinc finger protein A20, nuclear factor κB binding protein [P65, phosphate P65 (P-P65), collagen Ⅱ, aggrecan], inflammatory factors [tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β)], autophagy-related protein [LC3 (LC3Ⅱ/LC3Ⅰ) and P62] were detected by Western blot.ResultsThe comprehensive score of biological response in each group after injection was significantly lower than that before injection (P<0.05). At 6 days after injection, the comprehensive score of biological response in the Sh-A20 group was significantly lower than that in other groups (P<0.05), and there was no significant difference among other groups (P>0.05). The detection of MRI showed that the T2 signal value in the Ov-A20 group was the highest at 2, 4, and 8 weeks after injection (P<0.05), and the T2 signal value in the Sh-A20 group was the lowest at 2 and 4 weeks after injection (P<0.05). There was no significant difference between other groups (P>0.05). Alcian blue staining showed that the expression of aggrecan was the highest in Ov-A20 group and the lowest in Sh-A20 group at 4 weeks (P<0.05); the expression of aggrecan in Ov-A20 group was the highest at 8 weeks (P<0.05), and there was no significant difference between other groups (P>0.05). Immunohistochemical staining showed that the expressions of zinc finger protein A20, collagen Ⅱ, and aggrecan were the highest in Ov-A20 group and lowest in Sh-A20 group (P<0.05). Western blot showed that the expressions of zinc finger protein A20, collagen Ⅱ, aggrecan, and LC3 (LC3Ⅱ/LC3Ⅰ) proteins were the highest in the Ov-A20 group and the lowest in Sh-A20 group (P<0.05), while the expressions of P-P65, TNF-α, IL-1β, and P62 proteins were the lowest in Ov-A20 group and the highest in Sh-A20 group (P<0.05). There was no significant difference in the expression of p65 protein between groups (P>0.05).ConclusionZinc finger protein A20 can effectively regulate the process of lumbar intervertebral disc degeneration in rabbits by inhibiting inflammation.
Objective
To review the progress of the mechanisms of Wnt/β-catenin and nuclear factor-kappa B (NF-кB) pathways in the process of the intervertebral disc degeneration.
Methods
The related literature about the mechanisms of Wnt/β-catenin and NF-кB pathways in the process of the intervertebral disc degeneration was reviewed, analyzed, and summarized.
Results
Wnt/β-catenin and NF-кB pathways are both activated in the process of the intervertebral disc degeneration, and exist interaction. However, the specific mechanisms and interactive mediums of Wnt/β-catenin and NF-кB pathways in the process of the intervertebral disc degeneration are still unclear.
Conclusion
The mechanisms of Wnt/β-catenin and NF-кB pathways in the process of the intervertebral disc degeneration have to be studied deeply.
Objective To explorer the survival time of autogeneic BMSCs labeled by superparamagnetic iron oxide (SPIO) in rabbit intervertebral discs and the rule of migration so as to prove bases of gene therapy preventing intervertebral disc degeneration. Methods Twelve rabbits were used in this experiment, aged 8-10 weeks, weighing 1.5-2.0 kg and neglecting their gender. BMSCs were separated from rabbits bone marrow by density gradient centrifugation and cultivated, and the 3rd generation of BMSCs were harvested and labeled with SPIO, which was mixed with poly-l-lysine. The label ing efficiency was evaluated by Prussian blue staining and transmission electron microscope. Trypanblau stain and MTT were performed to calculate the cell’ s activity. Rabbits were randomly divided into experimental group (n=8) and control group (n=4), the labeled BMSCs and non-labeled BMSCs (5 × 105/mL) were injected into their own intervertebral discs (L1,2, L2,3, L3,4 and L4,5), respectively. At 2, 4, 6 and 8 weeks, the discs were treated with Perl’s fluid to observe cell survival and distribution. Results The label ing efficiency of BMSCs with SPIO was 95.65% ± 1.06%, the cell activity was 98.28% ± 0.85%. There was no statistically significant difference in cell prol iferation within 7 days between non-labeled and labeled cells (P gt; 0.05). After 8 weeks of operation, the injected cells was al ive. ConclusionLabeled BMSCs with SPIO is feasible in vitro and in vivo, and the cells can survive more than 8 weeks in rabbit discs.
