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.
ObjectiveTo investigate the influence of ISOBAR TTL dynamic internal fixation system on degeneration of adjacent intervertebral disc by MRI measurement of lumbar nucleus pulposus volume in treating lumbar degenerative disease after operation. MethodsBetween March 2010 and October 2011, 34 patients with lumbar intervertebral disc herniation (23 cases of paracentral type and 11 cases of lateral type) underwent operation with ISOBAR TTL dynamic internal fixation system for fixation of single segment, and the clinical data were analyzed retrospectively. There were 20 males and 14 females, aged 39-62 years (mean, 47.5 years). The disease duration was 6-18 months (mean, 14 months). Involved segments included L4, 5 in 21 cases and L5, S1 in 13 cases. The X-ray films and MRI images were taken at 6, 12, 18, 24, 36, and 48 months after surgery. Based on X-ray films, the height of intervertebral space was measured using angle bisectrix method. The nucleus pulposus volume was measured based on the MRI scan. The postoperative change of nucleus pulposus volume and intervertebral disc height were used to evaluate the influence of ISOBAR TTL system on degeneration of adjacent intervertebral disc nucleus pulposus. ResultsThirty patients were followed up 48 months. The height of intervertebral space showed no significant difference between at pre-and post-operation (P>0.05). The nucleus pulposus volume increased after operation, showing no significant difference at 6, 12, and 18 months when compared with preoperative value (P>0.05), but significant difference was found at 24, 36, and 48 months when compared with preoperative value (P < 0.05). The height of nucleus pulposus increased after operation but the width was decreased; the values showed no significant difference at 6, 12, and 18 months when compared with preoperative ones, but showed significant difference at 24, 36, and 48 months when compared with preoperative ones (P < 0.05). The diameter of nucleus pulposus at 18, 24, 36, and 48 months after operation was significantly langer than that at preoperation (P < 0.05). ConclusionISOBAR TTL dynamic internal fixation system can prevent or delay the degeneration of intervertebral discs.
Objective Bone marrow mesenchymal stem cells (BMSCs) transplantation can potentially regenerate the degenerated intervertebral disc, with the underlying regenerating mechanism remaining largely unknown. To investigate the potential of human BMSCs protecting nucleus pulposus cells (NPCs) from oxidative stress-induced apoptosis in a coculturesystem, and to illustrate the possible mechanisms of BMSCs transplantation for intervertebral disc regeneration. Methods BMSCs collected by density gradient centrifugation in Percoll solution were cultured and sub-cultured till passage 3, and the surface molecules of CD34, CD45, and CD13 were identified. NPCs were isolated by collagenase digestion and the chondrocyte l ike phenotype was confirmed by morphologic observation after HE staining, inverted phase contrast microscope, proteoglycan, and collagen type II expression after toluidine blue and immunocytochemistry staining. The 3rd passage BMSCs and the 1st passage NPCs were divided into four groups: group A, NPCs (1 × 106 cells) were cultured alone without apoptosis inducing (negative control); group B, NPCs (1 × 106 cells) were co-cultured with BMSCs (1 × 106 cells) with apoptosis inducing; group C, NPCs (1 × 106 cells) were co-cultured with BMSCs (3 × 105 cells) with apoptosis inducing; group D, NPCs (1 × 106 cells) were cultured alone with apoptosis inducing (positive control). After 3 or 7 days of culture or co-culture, the NPCs in groups B, C, and D were exposed to 0.1 mmol hydrogen peroxide for 20 minutes to induce apoptosis. With DAPI staining cellular nucleus, Annexin-V/propidium iodide staining cellular membrane for flow cytometry analysis, the apoptosis of NPCs in each group was studied both qual itatively and quantitatively. Besides, the changes in Bax/Bcl-2 gene transcription and Caspase-3 protein content, were analyzed with semi-quantitative RT-PCR and Western blot. Results BMSCs were successfully isolated and CD34-, CD45-, and CD13+ were demonstrated; after isolated from degenerated intervertebral discs and sub-cultured, the spindle-shaped 1st passage NPCs maintained chondrocyte phenotype with the constructive expressions of proteoglycan and collagen type II in cytoplasm. DAPI staining showed the nucleus shrinkage of apoptosis NPCs. Co-cultured with BMSCs for 3 days and 7 days, the apoptosis rates of NPCs in groups B (29.26% ± 8.90% and 18.03% ± 2.25%) and C (37.10% ± 3.28% and 13.93% ± 1.25%) were lower than that in group D (54.90% ± 5.97% and 26.97% ± 3.10%), but higher than that of groupA (15.67% ± 1.74% and 8.87% ± 0.15%); all showing significant differences (P lt; 0.05). Besides, semi-quantitative RT-PCR showed Bcl-2 gene transcription up-regulated (P lt; 0.05) and no significant change of Bax (P gt; 0.05); Western blot result showed that the Caspase-3 protein expression of groups B and C was lower than that of group D, and was higher than that of group A; all showing significant differences (P lt; 0.05). Conclusion In a co-culture system without direct cellular interactions, the oxidative stress-induced apoptosis of human NPCs was amel iorated by BMSCs. The enhanced anti-apoptosis abil ity of NPCs preconditioned by co-culturing with BMSCs might come from the decreased Bax/Bcl-2 gene transcription ratio.
Degenerative disc disease is a prevalent chronic disease that orthopaedic surgeons currently face as a difficulty. Tissue engineering represents the most promising possible therapeutic strategy for disc repair and regeneration. Surgery is the primary treatment for degenerative disc disease, but there are still inherent limits in practical practice. Electrospinning technique is a method for manufacturing nanoscale fibers with varied mechanical properties, porosity, and orientation, which can imitate the structural qualities and mechanical properties of natural intervertebral discs. Therefore, electrospinning materials can be utilized for disc regeneration and replacement. This article reviews recent advancements in disc tissue engineering and electrostatically spun nanomaterials typically utilized for the fabrication of disc scaffolds, as well as present and future techniques that may enhance the performance of electrostatically spun fibers.
Objective To detect the cell density, apoptotic rate, and the expressions of BNIP3 in nucleus pulposus of degenerative intervertebral disc of rabbits, so as to further understand the mechanism of intervertebral disc degeneration. Methods Thirty male New Zealand white rabbits, aging 3 months and weighing (2.3 ± 0.2) kg, were divided into sham operation group (control group, n=10) and intervertebral disc degeneration model group (experimental group, n=20). Interbertebral disc degeneration models were establ ished by puncture of L3,4, L4,5, and L5,6 intervertebral discs in the experimental group; intervertebral discs were exposed only and then sutured in the control group. The degree of intervertebral disc degeneration was evaluated according to Pfirrmann classification by MRI at 4 and 8 weeks after establ ishing models. Apototic cells were determined by TUNEL and histological methods, and the immunohistochemical staining was performed to detect the expressions of BNIP3 in nucleus pulposus of intervertebral disc. Results MRI examination showed that the signal intensity decreased gradually at 4 and 8 weeks in the experimental group. There wassignificant difference in the degree of intervertebral disc degeneration between at 4 weeks and at 8 weeks in the experimental group (P lt; 0.05). The histological observation and TUNEL test showed that high density of nucleus pulposus cells and only a few apoptotic cells were observed in the control group; at 4 and 8 weeks, the density of nucleus pulposus cells decreased gradually with more apoptotic cells in the experimental group. There were significant differences in the nucleus pulposus cell density and positive rate of TUNEL staining between 2 groups, and between at 4 weeks and at 8 weeks in the experimental group (P lt; 0.05). The expression of BNIP3 of nucleus pulposus was negative in the control group; however, in the experimental group, the positive expression rates of BNIP3 of nucleus pulposus (the gray values) were 13.45% ± 1.16% and 32.00% ± 1.82% (194.32 ± 4.65 and 117.54 ± 2.11) at 4 and 8 weeks respectively, showing significant differences (P lt; 0.05). Conclusion The decrease of cell density in nucleus pulposus is involved in the development of intervertebral disc degeneration. Cell apoptosis is one of reasons in the decrease of nucleus pulposus cell; BNIP3 is involved in nucleus pulposus cell apoptosis in the degenerative intervertebral disc.
Objective To summarize the research situation of stem cells transplantation for intervertebral disc (IVD) degeneration. Methods The original articles about stem cells transplantation for repair of IVD degeneration were extensively reviewed; the clinical applications, the mechanisms, and related factors to influence repair effect were analyzed; and obstacles in stem cells transplantation for repair of IVD degeneration. Results Autogenic stem cells transplantation can repair IVD degeneration and effectively relieve the symptoms of low back and leg pain. Stem cells can differentiate into disc chondrocytes in the disc microenvironment, increase the production of various growth factors, and exert a trophic effect on disc cells. It is also evident that the transplanted stem cells can potentially protect disc cells from apoptosis and maintain an immune-privileged state in the IVD. Multiple factors such as tissue origin of stem cells, methods to pre-modulate the seeds, choice of injectable scaffolds, and even the severity of degeneration are closely related to the repair effects. To get a more efficient stem cell therapy, future researches are challenged to modulate the migration and distribution of stem cells in the IVD, avoid flow back, and better understand their ability to restore stemness properties within the degenerative disc niche. Conclusion Stem cells transplantation is proven to be a promising biological approach for repair of IVD degeneration.
ObjectiveTo summarize the research progress of hydrogels for the regeneration and repair of degenerative intervertebral disc and to investigate the potential of hydrogels in clinical application.MethodsThe related literature about the role of hydrogels in intervertebral disc degeneration especially for nucleus pulposus was reviewed and analyzed.ResultsHydrogels share similar properties with nucleus pulposus, and it plays an important role in the regeneration and repair of degenerative intervertebral disc, which can be mainly applied in nucleus pulposus prosthesis, hydrogel-based cell therapy, non-cellular therapy, and tissue engineering repair.ConclusionHydrogels are widely used in the regeneration and repair of intervertebral disc, which provides a potential treatment for intervertebral disc degeneration.
Objective To research the transfer of adenovirus human bone morphogenetic protein 4 (Ad-hBMP-4) to human degenerative lumbar intervertebral disc cells in vitro and analyze its effect on the proteoglycan, collagen type II, and Sox9 of intervertebral disc cells. Methods Identified Ad-hBMP-4 was amplified and detected. Degenerative lumbar intervertebral disc cells were aspirated from the degenerative lumbar intervertebral disc of patients with Modic III level disc protrusion (aged, 27-50 years). The expressing position of collagen type II was identified in the intervertebral disc cells through the laser confocal microscope. The intervertebral disc cells at passage 1 were transfected with Ad-hBMP-4 as experimental group. After 3 and 6 days of transfection, RT-PCR was used to detect the mRNA expressions of proteoglycan, collagen type II, and Sox9, and Western blot to detect the expressions of proteoglycan and collagen type II proteins. Non-transfected cells at passage 1 served as control group. Results The virus titer of Ad-hBMP-4 was 5 × 106 PFU/mL. No morphological changes in the cells after transfection by Ad-hBMP-4. Collagen type II mainly expressed in the cell cytoplasm. The mRNA expressions of the proteoglycan, collagen type II, and Sox9 in experimental group at 3 and 6 days after transfection were significantly higher than those in control group by RT-PCR (P lt; 0.05), and the expressions of proteoglycan and collagen type II proteins were significantly higher than those in contorl group by Western blot (P lt; 0.05). There were significant differences between 3 days and 6 days in experimental group (P lt; 0.05). Conclusion Ad-hBMP-4 could transfect human degenerative lumbar intervertebral cells with high efficiency and promote collagen type II, proteoglycan, and Sox9 expressions. hBMP-4 may play an important role in the repair process during early disc degeneration.
Objective To summarize the research progress of intervertebral disc endogenous stem cells for intervertebral disc regeneration and deduce the therapeutic potential of endogenous repair for intervertebral disc degeneration. Methods The original articles about intervertebral disc endogenous stem cells for intervertebral disc regeneration were extensively reviewed; the reparative potential in vivo and the extraction and identification in vitro of intervertebral disc endogenous stem cells were analyzed; the prospect of endogenous stem cells for intervertebral disc regeneration was predicted. Results Stem cell niche present in the intervertebral discs, from which stem cells migrate to injured tissues and contribute to tissues regeneration under certain specific microenvironment. Moreover, the migration of stem cells is regulated by chemokines system. Tissue specific progenitor cells have been identified and successfully extracted and isolated. The findings provide the basis for biological therapy of intervertebral disc endogenous stem cells. Conclusion Intervertebral disc endogenous stem cells play a crucial role in intervertebral disc regeneration. Therapeutic strategy of intervertebral disc endogenous stem cells is proven to be a promising biological approach for intervertebral disc regeneration.
Objective To summarize the research progress of microRNA (miRNA) and its non-viral vector in intervertebral disc degeneration (IDD) and to investigate the potential of non-viral vector delivery of miRNA in clinical application. Methods The related literature about the role of miRNA in IDD and its non-viral delivery system was reviewed and analyzed. Results MiRNA can regulate the related gene expression level and further participate in the pathophysiologic process in degenerated intervertebral disc, miRNA delivered by various non-viral vectors has obtained an ideal effect in some diseases. Conclusion MiRNA plays a great role in the cellular and molecular mechanisms of IDD, as a safe and effective strategy for gene therapy, non-viral vector provides new possibilities for IDD treated with miRNA.