Intervertebral disc tissue engineering based on polymer materials: Research focus and hot spots / 中国组织工程研究

BACKGROUND: In recent years, the rapid development of tissue engineering technology provides a new idea for the treatment of intervertebral disc degeneration; that is, biomaterials are used to reconstruct the damaged intervertebral disc structure. OBJECTIVE: To summarize polymer materials which are applicable for intervertebraltissue engineering construction, and overview the advantages, disadvantages and application progress of each material. METHODS: We searched related articles from inception to February 2020 in PubMed, Web of Science and CNKI databases with “polymer, intervertebral disc, tissue engineering, nucleus pulposus, annulus fibrosus” as English and Chinese key words. Initially 189 related articles were searched, and 109 eligible articles were included in final analysis according to inclusion and exclusion criteria. RESULTS AND CONCLUSION: Intervertebral disc is composed of inner soft nucleus pulposus and outer stiff annulus fibrosus. Accordingly, it requires two components with different structures and functions to reconstruct a complete intervertebral disc with tissue engineering method. Chitosan, alginate and hyaluronic acid are considered as optimal materials for nucleus pulposus construction because of their appropriate swelling character and ability of inducing cells to secrete nucleus pulposus matrix. Silk fibroin, collagen, polyethylene glycol, polylactic acid, polyglycolic acid and polycaprolactone with high mechanical strength are suitable for annulus fibrosus construction to bear high loading burden. By further surface modification, these synthesis scaffolds wound show a better cellular compatibility and promote tissue integrity after in vivo implantation.

Biomechanical characteristics of the lumbar disc after fatigue injury / 中国组织工程研究

BACKGROUND: Lumbar disc herniation is a common clinical disease, and its pathological basis is disc degeneration. Long-term mechanical load is considered to be an important cause of lumbar disc degeneration. Because the occurrence of lumbar disc herniation is strongly associated with its mechanical state, it is necessary to further study the stress/strain behavior in the lumbar disc to provide inspiration for preventing lumbar disc herniation. OBJECTIVE: To analyze the effect of fatigue loading on mechanical properties of the whole and different regions of the intervertebral disc. METHODS: The freshly slaughtered sheep lumbar intervertebral discs L1-L2, L3-L4, and L5-L6 were obtained and made into experimental samples. The experimental samples were fixed on the experimental platform through the upper and lower vertebrae, and a quasi-static compression-cyclic loading compression-quasi-static compression experiment was performed. The L3-L4 motion segment was cut parallel to the sagittal plane, and the non-contact digital image correlation technique was used to record the internal deformation of the lumbar disc during compression. RESULTS AND CONCLUSION: (1) The results showed that all lumbar intervertebral discs exhibited non-linear load-displacement and stress-strain characteristics. (2) Effect of fatigue loading: The Young’s modulus of the lumbar intervertebral disc increased significantly after fatigue loading. (3) Impact of segment changes: The Young’s modulus changed with segment changes as follows: L5-L6 segments < L3-L4 segments < L1-L2 segments. (3) Effect of loading rate: Comparing the mechanical properties under the compression rate of 0.01 mm/s and 0.1 mm/s, it could be seen that with the increase of the compression rate, the Young’s modulus of the intervertebral disc increased significantly. (5) Internal displacement distribution: Fatigue loading had a significant effect on the internal displacement distribution of the lumbar disc under compression. Before fatigue loading, the axial displacement in upper afferent fiber was largest, and the radial displacement in inner afferent fiber was slightly smaller than that in outer afferent fiber. After fatigue loading, the axial displacement in upper afferent fiber was smallest, and the radial displacement in inner afferent fiber was significantly smaller than in outer afferent fiber. (6) The research work in this article has important theoretical guiding significance for preventing lumbar disc herniation in daily life.

P38/akt pathway regulates the oriented differentiation of bone marrow mesenchymal stem cells in nanofiber annulus fibrosus scaffolds with different spatial structures / 中国组织工程研究

BACKGROUND: Previous studies have shown that a variety of materials can be used for the construction of tissue engineering scaffolds. The topological structure of the scaffold surface has a regulatory effect on the biological behaviors such as stem cell proliferation and differentiation, but the specific mechanism is still unclear. OBJECTIVE: To investigate the role of P38 and Akt pathways in the oriented differentiation of bone marrow mesenchymal stem cells in nanofiber scaffolds. METHODS: Three kinds of nanofiber scaffolds (AFS, AYS, 3-DPS) with different structures were constructed. Rat bone marrow mesenchymal stem cells were inoculated on the surface of three kinds of nanofiber scaffolds. After osteogenic induction, cell morphology, adhesion and proliferation were detected. mRNA expression levels of key phenotype molecules (COLIα1, COLIIα1, Aggrecan, Sox-9) were measured using qRT-PCR. Intracellular P38, AKT, ERK1/2 and JNK expression was detected by western blot assay. RESULTS AND CONCLUSION: After 4 and 8 hours of culture, cell adhesion rate of the 13-DPS scaffold group was higher than that of the AFS and AYS scaffold groups (P<0.05). After 7 days of culture, cells of the 13-DPS scaffold group proliferated faster than those of AFS and AYS scaffold groups (P<0.05). Bone marrow mesenchymal stem cells adhered firmly and grew well on three kinds of scaffolds. Fibroblast-like growth was observed on the AFS and AYS scaffolds and chondrocyte-like growth was observed on the 3-DPS scaffold. After 3 weeks of cartilage induction, mRNA expression of COLIIα1, Aggrecan and Sox-9 was higher, and the mRNA expression of COLIα1 was lower, in the 3-DPS scaffold group compared with the other two groups (both P<0.05). After 3 weeks of cartilage induction, relative expression level of p-AKT and p-P38 in the 3-DPS scaffold group was significantly higher than that in the other two groups (both P<0.05). There were no significant differences in AKT total protein and ERK1/2, JNK, P38, p-ERK1/2, p-JNK and p-P38 protein expression levels among three groups. These findings suggest that nanofiber annulus fibrosus scaffolds with different spatial structures can induce the oriented differentiation of bone marrow mesenchymal stem cells through the P38 and AKT pathway, which were the downstream of the Integrin-FAK signaling pathway.

Research progress of intervertebral disc repair with decellularized matrix materials / 中国组织工程研究

BACKGROUND: With the development of tissue engineering, the repair and regeneration of disc becomes possible. Decellularized extracellular matrix is an important means for disc regeneration. OBJECTIVE: To review and summarize the processing, quality control and application of decellularized matrix materials applied in intervertebral disc regeneration in recent years and put forward the prospect. METHODS: PubMed, Web of Science and CNKI databases were searched for the articles concerning decellularized methods and decellularized matrix repairing intervertebral disc with the search terms of “intervertebral disc, decellularization, extracellular matrix, scaffold material, tissue engineering” in English and Chinese, respectively. After screening based on the inclusion and exclusion criteria, the articles with high relevance were included for review. RESULTS AND CONCLUSION: The decellularized tissue-engineered intervertebral disc aims to maintain the physiologically relevant bioactivators to a great extent, improve mechanical properties and biocompatibility, and reduce immunogenicity. The decellularized matrix material can simulate the microenvironment of the extracellular matrix in the intervertebral disc. As a cell carrier, it can well induce the differentiation of seed cells, which has achieved certain progress in the repair of intervertebral discs. However, further studies need to address the following issues: proper porosity of decellularized matrix materials, immunological rejection, implant ways in vivo and repair effect.

Quantitative Predictive Imaging Biomarkers of Lumbar Intervertebral Disc Degeneration

STUDY DESIGN: Observational comparative study. PURPOSE: To compare fractional anisotropy (FA) maps with T2 values of the nucleus pulposus (NP) and annulus fibrosus (AF) of intervertebral discs in healthy volunteers and patients to develop a predictive disc health scale. OVERVIEW OF LITERATURE: T2-weighted magnetic resonance imaging (MRI) is not sensitive to early morphological changes and provides no quantitative biomarker profile for early degeneration. METHODS: We examined 59 healthy controls and 59 patients with back pain by MRI using T2 relaxometry and diffusion tensor imaging (DTI). Each group was divided into three age subgroups: A (50 years, n=21). We obtained FA values for AF and NP and T2 values for NP for each intervertebral disc. Furthermore, we calculated the FA (AF/NP) ratios. RESULTS: We categorized 590 intervertebral discs from 118 participants, 566 of which were analyzed with T2 relaxometry and DTI. The T2 values were as follows: subgroup A, 55.8±4.4 ms; B, 48.5±6.9 ms; C, 45.8±8.7 ms (p120 ms, 90–100 ms, and 70 ms, respectively (p<0.001). Control subgroup A had higher T2 values and AF/NP ratios than subgroups B and C; the AF values were not significantly different. Control subgroup B had higher T2 values and AF/NP ratios than subgroup C but lower FA (NP). CONCLUSIONS: FA maps of the AF/NP ratio and T2 values of NP are potential microstructure biomarkers of normal and degenerating discs and can help detect early degeneration using a predictive disc health score on a continuous scale.

Efficacy of transforaminal laser annuloplasty versus intradiscal radiofrequency annuloplasty for discogenic low back pain

BACKGROUND: Discogenic pain is a common cause of disability and is assumed to be a major cause of non-specific low back pain. Various treatment methods have been used for the treatment of discogenic pain. This study was conducted to compare the therapeutic success of radiofrequency (an intradiscal procedure) and laser annuloplasty (both an intradiscal and extradiscal procedure). METHODS: This single-center study included 80 patients and followed them for 6 months. Transforaminal laser annuloplasty (TFLA, 37 patients) or intradiscal radiofrequency annuloplasty (IDRA, 43 patients) was performed. The main outcomes included pain scores, determined by the numeric rating scale (NRS), and Oswestry disability index (ODI), at pre-treatment and at post-treatment months 1 and 6. RESULTS: The patients were grouped according to procedure. In all procedures, NRS and ODI scores were significantly decreased over time. Mean post-treatment pain scores at months 1 and 6 were significantly lower (P 40%. CONCLUSIONS: Our results indicate that annuloplasty is a reasonable treatment option for carefully selected patients with lower back and radicular pain of discogenic origin, and TFLA might be superior to IDRA in patients with discogenic low back pain.

Energy supply and demand in the intervertebral disc / Fornecimento e demanda de energia no disco intervertebral / Suministro de energía y demanda en el disco intervertebral

ABSTRACT The intervertebral disc (IVD) is one of the parts of the body most commonly affected by disease, and it is only recently that we have come closer to understanding the reasons for its degeneration, in which nutrient supply plays a crucial role. In this literature review, we discuss the basic principles and characteristics of energy supply and demand to the IVD. Specifically, we review how different metabolites influence IVD cell activity, the effects of mechanical loading on IVD cell metabolism, and differences in energy metabolism of the annulus fibrous and nucleus pulposus cell phenotypes. Determining the factors that influence nutrient supply and demand in the IVD will enhance our understanding of the IVD pathology, and help to elucidate new therapeutic targets for IVD degeneration treatment.

RESUMO O disco intervertebral (IVD) é uma das partes mais comuns do corpo e apenas recentemente nos aproximamos de compreender as razões da sua degeneração, em que o suprimento de nutrientes desempenha um papel crucial. Nesta revisão da literatura, discutimos os princípios básicos e as nuances do fornecimento e da demanda de energia para o IVD. Específicamente, analisamos como os diferentes metabólitos influenciam na atividade das células IVD, os efeitos da carga mecânica no metabolismo das células IVD, a diferença no metabolismo energético dos fenótipos das células fibrosas e do núcleo do pulposus anelar. A determinação de fatores que influenciam o suprimento e a demanda de nutrientes no IVD aumentará nossa compreensão da patologia IVD e ajudará a elucidar novos alvos terapêuticos para o tratamento da degeneração IVD.

RESUMEN El disco intervertebral (IVD, por sus siglas en inglés) es una de las partes más comúnmente enfermas del cuerpo y solo recientemente nos acercamos a la comprensión de los motivos de su degeneración, de los cuales el suministro de nutrientes juega un papel crucial. En esta revisión de la literatura discutimos los principios básicos y los matices de la oferta y demanda de energía para el IVD. Específicamente, revisamos cómo los diferentes metabolitos influyen en la actividad de las células IVD, los efectos de la carga mecánica sobre el metabolismo de las células IVD y las diferencias en el metabolismo energético de los fenotipos de las células del anillo fibroso y el núcleo pulposo. La determinación de los factores que influyen en la oferta y demanda de nutrientes en el IVD mejorará nuestra comprensión de la patología IVD y ayudará a dilucidar nuevos objetivos terapéuticos para el tratamiento de la degeneración IVD.

Outcomes of surgical treatment of lumbar disk herniation using an annular closure device / Desfechos do tratamento cirúrgico da hérnia de disco lombar com aparelho de fechamento anular / Resultados del tratamiento quirúrgico de la hernia de disco lumbar utilizando un dispositivo de cierre anular

ABSTRACT Objective: The aim of the study was to investigate the clinical and radiological results of using the annular closure device in patients with lumbar disc herniation (LDH). Methods: The study involved 120 patients with LDH operated on by limited discectomy and annular closure using the Barricaid device. A literature review was conducted to evaluate the effectiveness of the annuloplasty. Results: All patients showed postoperative regression of the radicular pain syndrome and were mobilized on the day of surgery. The correlation between the removed nucleus pulposus and changes in DHI was studied by linear regression. The results revealed that disc height loss is directly correlated with the volume of removed nucleus pulposus (p <0.05). Modic changes were present in 22 (22%) patients. Endplate changes (resorption and erosion) were present in 25 patients (20.7%). We found that these changes in MR and CT images have no effect on the clinical presentation of the disease. No intraoperative complications, such as severe hemorrhage requiring blood transfusion, or injury to the dura mater or nerve roots, were observed in our case series. Postoperative complications occurred in 3 (2.5%) patients. The reoperation rate was 4.2%. Conclusions: The use of the Barricaid annular closure device in 120 patients with lumbar disc herniation and high risk of recurrent herniation showed good clinical and radiographic outcomes. The reoperation rate in our study was 2.5%; disc reherniation at the operated level was observed in 1.7% of patients. This is a good outcome compared to the data reported for patients having a high risk of disc reherniation. Level of Evidence IV; Case series.

RESUMO Objetivo: O objetivo do estudo foi estudar os resultados clínicos e radiológicos do uso do dispositivo de fechamento anular em pacientes com hérnia discal lombar (HDL). Métodos: O estudo envolveu 120 pacientes com LDH operados por discectomia limitada e fechamento anular usando o dispositivo Barricaid. Uma revisão da literatura foi realizada para avaliar a eficácia da anuloplastia. Resultados: Todos os pacientes apresentaram regressão pós-operatória da síndrome da dor radicular e foram mobilizados no dia da cirurgia. A correlação entre o núcleo pulposo removido e as alterações no DHI foi estudada por regressão linear. Revelou-se que a perda de altura discal está diretamente correlacionada com o volume do núcleo pulposo removido (p <0,05). Alterações modicadas reveladas em 22 (22%) pacientes. As alterações no endplate foram reveladas em 25 pacientes (20,7%). Descobrimos que essas mudanças nas imagens de RM e TC não têm efeito sobre a apresentação clínica da doença. Não foram observadas complicações intraoperatórias, como hemorragia grave que necessitou de transfusão sanguínea, lesão da dura-máter ou raízes nervosas, em nossa casuística. Complicações pós-operatórias foram reveladas em 3 (2,5%) pacientes. A taxa de reoperação foi de 4,2%. Conclusão: O uso do dispositivo de fechamento anular Barricaid em 120 pacientes com hérnia discal lombar e alto risco de hérnia recorrente mostrou bons resultados clínicos e radiográficos. A taxa de reoperação em nosso estudo foi de 2,5%; reinteriato discal no nível operado foi observado em 1,7% dos pacientes. É um bom resultado comparado aos dados relatados para pacientes com alto risco de reintervenção com disco. Nível de evidência IV; Série de casos.

RESUMEN Objetivo: El objetivo del estudio fue estudiar los resultados clínicos y radiológicos del uso del dispositivo de cierre anular en pacientes con hernia de disco lumbar (LDH). Métodos: El estudio involucró a 120 pacientes con LDH operados por discectomía limitada y cierre anular usando el dispositivo Barricaid. Se realizó una revisión de la literatura para evaluar la efectividad de la anuloplastia. Resultados: Todos los pacientes mostraron regresión postoperatoria del síndrome de dolor radicular y se movilizaron el día de la cirugía. La correlación entre el núcleo pulposo retirado y los cambios en DHI se estudiaron mediante regresión lineal. Los resultados revelaron que la pérdida de altura del disco se correlaciona directamente con el volumen del núcleo pulposo retirado (p <0,05). Cambios módicos revelados en 22 (22%) pacientes. Los cambios de placa terminal (resorción y erosión) se revelaron en 25 pacientes (20,7%). Descubrimos que estos cambios en las imágenes de RM y TC no tienen ningún efecto sobre la presentación clínica de la enfermedad. En nuestra serie de casos no se observaron complicaciones intraoperatorias, como hemorragia severa que requiriera transfusión de sangre, lesión de la duramadre o raíces nerviosas. Las complicaciones postoperatorias se revelaron en 3 (2,5%) pacientes. La tasa de reoperación fue del 4,2%. Conclusiones: El uso del dispositivo de cierre anular Barricaid en 120 pacientes con hernia de disco lumbar y alto riesgo de hernia recurrente mostró buenos resultados clínicos y radiográficos. La tasa de reoperación en nuestro estudio fue del 2.5%; la hernia recurrente del disco en el nivel operado se observó en el 1,7% de pacientes. Es un buen resultado en comparación con los datos informados para pacientes que tienen un alto riesgo de hernia recurrente del disco. Nivel de evidencia IV; Serie de casos.

Tissue Engineering of the Intervertebral Disc's Annulus Fibrosus: A Scaffold-Based Review Study

Tissue engineering as a high technology solution for treating disc's problem has been the focus of some researches recently; however, the upcoming successful results in this area depends on understanding the complexities of biology and engineering interface. Whereas the major responsibility of the nucleus pulposus is to provide a sustainable hydrated environment within the disc, the function of the annulus fibrosus (AF) is more mechanical, facilitating joint mobility and preventing radial bulging by confining of the central part, which makes the AF reconstruction important. Although the body of knowledge regarding the AF tissue engineering has grown rapidly, the opportunities to improve current understanding of how artificial scaffolds are able to mimic the AF concentric structure—including inter-lamellar matrix and cross-bridges—addressed unresolved research questions. The aim of this literature review was to collect and discuss, from the international scientific literature, information about tissue engineering of the AF based on scaffold fabrication and material properties, useful for developing new strategies in disc tissue engineering. The key parameter of this research was understanding if role of cross-bridges and inter-lamellar matrix has been considered on tissue engineering of the AF.

Treatment of Targeted Percutanous Ozone Ablation on Lumbar Disc Herniation with High Intensity Zone in Lumbar Disc Annulus Fibrosus / 现代生物医学进展

Objective:To observe the clinical effects of targeted percutanous ozone ablation on lumbar disc herniation (LDH) patients with high intensity zone (HIZ) in lumbar disc annulus fibrosus on MRI T2 weighted imaging.Methods:136 LDH patients with HIZ in lumbar disc annulus fibrosus on MRI T2 were divided into two groups according to therapy methods.In group A,75 patients were injected with 2 ～5 mL of 40 μg/mL mixture of O3 and O2 after targeted percutanous puncturing under the guidance of X-Ray machine with C-type arm.In group B,61 patients were treated with conservative treatment.MacNab score criterion and Oswestry disability index (ODI) were used in assessment of the efficacy.Results:Except 24 patients,all the other cases were followed up for 18 ～ 44 months.At the postoperative 1st,2nd,3rd,6th,9th,12th and 18th month,according to MacNab score criterion,the effective rates were respectively 88.00 ％,90.67 ％,93.33 ％,89.39 ％,84.85 ％,78.13 ％ and 73.44 ％ in group A and respectively 68.85 ％,62.30 ％ 55.74 ％,61.82 ％,58.12 ％,54.17 ％ and 47.92 ％ in group B.There were significant differences between two groups at the same time point (P＜0.05).At the postoperative 12th and 18th month,ODI was lower in group A,and there was no significant difference between two time points (P＞0.05).But it was significant different with that preoperatively and in group B at the same time point (P＜0.05).Conclusion:Targeted percutanous ozone ablation is an effective method with stable clinical efficacy in treating LDH with HIZ in lumbar disc annulus fibrosus on MRI T2 weighted imaging.

Expression and significance of MMP-1 and TIMP-1 in the nucleus pulposus and anulus fibrosus of intervertebral disc with different lesions / 局解手术学杂志

Objective To explore the expression and significance of MMP-1 and TIMP-1 in the nucleus pulposus and anulus fibrosus of intervertebral disc with different lesions.Methods From August 2014 to August 2016,34 cases of lumbar disc herniation (the observation group) and 34 case of surgical removal of intervertebral disc in patients with vertebral trauma caused by sudden trauma (the control group) in our hospital were stuided.The nucleus pulposus and anulus fibrosus of intervertebral disc were separated,and the expression of MMP-1 and TIMP-1 were detected by immunohistochemistry.The relationship between MMP-1 and TIMP-1 expression and intervertebral disc degeneration was analyzed.Results The MMP-1 and TIMP-1 expression of nucleus pulposus in the observation group were significantly higher than those in the control group(P>0.05);and the MMP-1 and TIMP-1 expression of nucleus pulposus decreased successively in prominent type,extrusion type,free type lumbar intervertebral disc degeneration(P0.05);and the MMP-1 and TIMP-1 expression of anulus fibrosus decreased successively in prominent type,extrusion type,free type lumbar intervertebral disc degeneration(P<0.05).Patients with high expression of MMP-1 and TIMP-1 in nucleus pulposus and anulus fibrosus had more risk of degenerative disc disease(P<0.05).As a sensitivity prediction of intervertebral disc degeneration,the sensitivity of MMP-1 was 82.35% while the specificity was 94.11%,and the sensitivity of TIMP-1 was 79.41% while the specificity was 88.24%.The prediction sensitivity of intervertebral disc degeneration was 90.91% and the specificity was 97.14% when combined MMP-1 with TIMP-1.Conclusion The expression of MMP-1 and TIMP-1 in the nucleus pulposus and anulus fibrosus of intervertebral disc degeneration was significantly increased,which is of great clinical significance in the diagnosis of intervertebral disc degeneration.

Establishment of annulus fibrosus partial defect model in sheep / 天津医药

Objective To establish an animal model of annulus fibrosus (AF) partial defect for the repairing of interver?tebral disc (IVD) defect. Methods Image J 1.46r software was used to measure the T12/L1-L6/S1 intervertebral height in ovine lumbar spine X-ray films. AF thickness was measured by axial split disc. A 11 blade was used to make a trapezoid de?fect of upper bottom 3 mm, lower bottom 5 mm, height 5 mm and thickness 3 mm, whose lower bottom toward the nucleus pulposus (NP) in the left front of ovine lumbar IVD in vitro. The minimally invasive lateral approach was used to make the same type of trapezoid defect in the left front of the ovine lumbar IVD in vivo. The trapezoidal defect length of the axial divid?ing disc was measured, AF and a small amount of NP from trapezoidal defect in IVD were weighed, and the production of trapezoidal defect in IVD was evaluated. Results The lumbar intervertebral space height of ovine was (4.45 ± 0.28) mm. There were significant differences in the thickness of AF (4.08±0.50) mm , thickness (3 mm) and height (5 mm) of trapezoidal defect (P0. 05). The weights of the AF and NP taken out from ovine lumbar IVD in vitro and in vivo were (0.162 ± 0.011) g and (0.166 ± 0.014) g, and there was no significant difference between them (P > 0.05). Conclusion Through the operation of minimally invasive lateral approach, the method of making a trapezoidal defect in the experiments can establish animal model of AF partial defect, which meets the requirements for the repairing of IVD defect, and is simple, safe and reliable.

Manufacture and evaluation of integrated biphasic silk fibroin scaffold made by annulus fibrosus-nucleus pulposus tissue engineering / 天津医药

Objective To assess the prospect of integrated biphasic silk fibroin scaffold made by annulus fibrosus-nu?cleus pulposus tissue engineering in application as integrated intervertebral disc(IVD). Methods An integrated annulus fi brosus-nucleus pulposus(AF-NP)biphasic scaffold was made by silk fi broin using two different uncomplicated methods which were paraffin spheres-leaching method(outer AF phase)and phase separation method(inner NP phase). The scaf?fold was investigated by general observation, stereomicroscope and scanning electron microscopy(SEM). Its pore size, poros?ity, and compressive elastic modulus were determined. AF and NP cells were isolated from rabbit IVD and seeded into the corresponding phase of the scaffold respectively. The cell-scaffold complex was cultured for 48 hours. The biocompatibility of the scaffold was evaluated by SEM, live/dead staining while CCK-8 assay was used to assess cell proliferation. Results Stereomicroscope and SEM showed that AF phase and NP phase integrated perfectly without cross-linking. Both phases pos?sessed highly interconnected porous structure [pore size of AF and NP phase were(220.0±23.1)μm and(90.0±17.8)μm, re?spectively] and highly porosity(AF and NP phase were respectively 91%and 93%). In addition, this silk biphasic scaffold had impressive mechanical properties(150.7 ± 6.8)kPa. SEM revealed that disc cells attached to regions of pore walls, dis?tributed uniformly and secreted extracellular matrix. Live/Dead staining and cell count kit-8(CCK-8)analysis showed that the silk composite scaffold was non-cytotoxic to disc cells. Conclusion This silk biphasic AF-NP scaffold has satisfied pore size, porosity, biomechanical properties and biocompatibility, so it is ideal candidate for IVD tissue engineering.

Repair Using Conventional Implant for Ruptured Annulus Fibrosus after Lumbar Discectomy: Surgical Technique and Case Series

STUDY DESIGN: A retrospective review of annulus fibrosus repair (AR) using a novel technique with a conventional implant. PURPOSE: The purpose of this study was to present the feasibility and clinico-radiological outcomes of a novel AR technique using a conventional implant to minimize recurrence following a lumbar discectomy (LD). OVERVIEW OF LITERATURE: Conventional repair techniques to prevent recurrence following LD have several drawbacks. The AR surgical technique has received little attention as an adjunct to LD. METHODS: A total of 19 patients who underwent novel AR following LD, and who were available for follow-up for at least three years, were enrolled in this study. Several variables, including the type and size of disc herniation, and the degree of disc degeneration, were evaluated preoperatively. Postoperatively, the presence of clinical and radiological recurrence of disc herniation was evaluated from pain intensity and functional statuses, as well as an enhanced L-spine magnetic resonance imaging at the final follow-up. The presence of a peripheral hollow rim and inserted anchor mobilization were also evaluated during the follow-up. RESULTS: During follow-ups, there were no recurrences of disc herniation or complications, including neurovascular complications. Pain and functional disability improved significantly after surgery, and the improvement was maintained throughout the three-year follow-up period. No mobilization or implant peripheral hollow rim was observed during the follow-up. CONCLUSIONS: This study examined the feasibility of a novel and easily available annulus implant technique following LD. These results suggest performing AR with this technique may be a valuable alternative for optimizing outcomes, if the procedure is performed in proper candidates.

Generation of Proinflammatory Mediator of Intervertebral Disc Cells by Nicotine Stimulation

STUDY DESIGN: Experimental investigation in vitro. OBJECTIVES: To evaluate the relationship between the degeneration of intervertebral disc cells, and low back pain induced by degeneration of intervertebral disc cells and increases in use of proinflammatory mediators via nicotine stimulation. SUMMARY OF LITERATURE REVIEW: Smoking is a leading cause of degeneration of intervertebral disc cells and low back pain. According to the existing literature, nicotine, one of the main ingredients in cigarettes, causes the degeneration of intervertebral disk cells including decrease of glycoprotein through generation of carboxy-hemoglobin, vasoconstriction, and disability of fibrinolysis and changes of metabolism of nucleus pulposus cells. MATERIALS AND METHODS: Annulus fibrosus of intervertebral disc and knee joint cartilage were collected from pigs; these cells were acquired by gradual enzyme decomposition. Using Trypan blue, concentration and survival rate of cells were examined; cells were inserted on alginate beads for tertiary cultivation. Nicotine was then applied at 0, 50, 100, 200 and 300 nM, respectively, and the samples were cultivated for three, six and nine days, respectively. After collecting culture fluid, it was measured for interleukin(IL)-1beta, IL-6 and IL-8 with the ELISA Test. DNA of cells used for cultivation was quantitated and the amount of the resulting proinflammatory mediator was normalized. The results were then compared with the result of same study on cartilage of porcine knee joints. RESULTS: For changes of the inflammatory mediator based on the concentration of nicotine, in nicotine stimulation with low concentration of 50 nM and the control group, there was no significant change, while transient increases of inflammatory mediator showed in nicotine stimulation with concentrations of 100, 200 nM, respectively. There was not a significant increase of IL-1beta observed in all nicotine stimulation groups; these were the same results in porcine cartilage study. The level of IL-6 in 200, 300 nM nicotine concentration showed significant increases, respectively. The level of IL-8 in high dose nicotine stimulation groups also showed significant increases of DNA on the sixth day. And in porcine cartilage study group, significant changes were observed in 200, 300 nM, but the absolute value was lower than that of annulus fibrous cells group. CONCLUSION: Inflammatory mediators such as IL-6 and IL-8 increased as the result of tertiary cultivation of annulus fibrosus cells of porcine intervertebral disk and nicotine stimulation. It is believed that the cells of the disc annulus are more sensitive than articular chondrocytes to nicotine stimulation. This may be the focus of future long-term studies effects of nicotine other inflammatory cytokines.

Effects of different decellularization methods on biomechanical properties and histological structure of annulus fibrosus in pigtail / 医用生物力学

Objective To investigate effects of different de-cellularization methods on biomechanical properties and histological structure of annulus fibrosus in pigtails and provide experimental evidence for the construction of tissue engineering annulus fibrosus. Methods Sixty Fresh annulus fibrosus were dissected from caudal disks of pigs and randomly assigned to 4 groups with 15 in each group. Triton X-100 group(Group A): annulus fibrosus were treated with hypotonic Tris-HCl buffer for 48 hours and de-cellularized with Triton X-100, DNase Ⅰ and RNase A. SDS group (Group B): annulus fibrosus were subjected to 3 cycles of freeze-thaw and subsequently de-cellularized with SDS, DNaseⅠ and RNase A. Trypsin group (Group C): annulus fibrosus were de-cellularized with Tris buffer containing trypsin, DNase Ⅰ and RNase A. Control group: fresh annulus fibrosus underwent no treatment. After the de-cellularization process was completed, hematoxylin-eosin (HE) staining was carried out to examine the efficacy on cell removal, and the ultrastructure of annulus fibrosus were observed by scanning electron microscopy. The collagen content, glycosaminoglycan (GAG) content and biomechanical parameters in each group were also detected. Results HE staining and scanning electron microscopy showed that no residual cells were found in Group A, B and C. The structure of annulus fibrosus in Group A was not disturbed, while that in Group B and C was damaged severely and slightly, respectively. There was no statistical difference in collagen content among Group A, B and C, as compared to the control group (P>0.05). But the GAG content was significantly more lower in Group A, B and C than in the control group (P0.05), while these parameters of Group B were lower than those in the control group (P<0.05). Conclusions The Triton X-100-treated annulus fibrosus retained the major extracellular matrix composition after cell removal and preserved the major structure and mechanical strength, which is preferable for the construction of tissue engineering annulus fibrosus.

Study of the proliferation ability of human degenerate nucleus pulposus and annular fibrosus cell in vitro / 国际生物医学工程杂志

ObjectiveTo explore the proliferation of human degenerate nucleus pulposus and annular fibrosus cell in vitro and compare the different biological behavior between the two kinds of cell after degeneration,and provide the new theoretical basis for the prevention and treatment of degenerative disc disease.MethodsThe samples of intervertebral disc tissue were collected from patients with lumbar disc herniation.The degree of degeneration was assessed by the pathological diagnosis and degenerate nucleus pulposus and annular fibrosus cell were cultured by enzymatic digestion and identified.In each case,the control groups of the nucleus pulposus cells and annulus fibrosus cells were cultured to the fifth generation.The inoculation density of cells was 1×105.The cell morphology of each generation was observed,while the proliferation of cells was detected by flow cytometry after 48h culture with the same conditions.ResultsThe degenerate nucleus pulposus cell and annular fibrosus cell were in good condition in vitro.The percentages of S phase cell and proliferation index (PI) were both on the rise with the subculture.The PI of nucleus pulposus cells reached the peak in the 3rd generation; The PI of annulus cells was the highest in the generation 5.The proliferation activity of degenerate nucleus pulposus cell in 2～4 generations was higher than the degenerate annular fibrosus cell within the same generations (P＜0.05).ConclusionDifferent proliferative characteristics of the degenerate nucleus pulposus and annular fibrosus cell confirmed that the disc degeneration is reversible.The response mechanisms to the degenerate micro-environment are completely different in vivo and affects the entire disc degeneration progress.

Primary Limited Lumbar Discectomy with an Annulus Closure Device: One-Year Clinical and Radiographic Results from a Prospective, Multi-Center Study

OBJECTIVE: Discectomy as a treatment for herniated lumbar discs results in outcomes after surgery that are not uniformly positive. Surgeons face the dilemma between limited nucleus removal which is associated with a higher risk of recurrence, or more aggressive nucleus removal which may lead to disc height loss and persistent back-pain. annulus closure devices may allow for the benefits of limited nucleus removal without the increased risk of recurrence. This is an interim report of an ongoing 24-month post-marketing study of the Barricaid(R) annulus closure device, consisting of a flexible polymer mesh that blocks the defect, held in place by a titanium bone anchor. METHODS: We prospectively enrolled 45 patients at four hospitals, and implanted the Barricaid(R) after a limited discectomy. annulus defect size and volume of removed nucleus were recorded. Reherniations were reported, pain and function were monitored and imaging was performed at regular intervals during 24 months of follow-up. RESULTS: At 12 months postsurgery, pain and function were significantly improved, comparing favorably to reported results from limited discectomy. Disc height has been well maintained. One reherniation has occurred (2.4%), which was associated with a misplaced device. No device fracture, subsidence or migration has been observed. CONCLUSION: The use of an annulus closure device may provide a reduction in reherniation rate for lumbar discectomy patients with large annulus defects who are at the greatest risk of recurrence. Using such a device should provide the surgeon increa- sed confidence in minimizing nucleus removal, which, in turn, may preserve disc height and biomechanics, reducing dege- neration and associated poor clinical outcomes in the long-term. A randomized multicenter study evaluating limited discectomy with and without the Barricaid(R) is currently underway, and will provide a higher level of evidence.

Light Microscopic Study of The Lumbar Intervertebral Disc Showing Inherent Difference Between Anterior & Posterior Annulus Fibrosus - A Risk Factor For Posterior Disc Herniation.

The present study is based upon the light microscopic observations made on the foetuses to determine the structural discrepancy in anterior and posterior annulus fibrosus in the development of human foetal lumbar intervertebral disc. A morphological comparison of the structure of anterior and posterior annulus fibrosus was made to consider the arrangement of lamellar bundles. As the foetus advances in age, the anterior annulus fibrosus becomes thicker than the posterior annulus. A very intricate structure was observed in posterior annulus with large number of loose and discontinuous lamellar bundles and more fibre-interlacing angles. Loose connection of the lamellar bundles in posterior annulus of almost all the foetuses indicates an inherent weakness which may lead to posterior rupture of the disc in later life.

Rabbit Annulus Fibrosus Cell Apoptosis Induced by Mechanical Overload via a Mitochondrial Apoptotic Pathway / 华中科技大学学报（医学）（英德文版）

In order to investigate the apoptotic pathway of rabbit annulus fibrosus(AF)cells induced by mechanical overload,an experimental air-pressure model was established in this study to pressurize the rabbit AF cells in vitro.Cells were randomly divided into five groups in which the cells were exposed to a continuous pressure of 1.1 MPa for different lengths of time(0,5,12,24 and 36 h).The cell proliferation and apoptosis were detected by cell counting kit-8(CCK-8)assay and flow cytometry; thealterations in mitochondrial membrane potential were measured by fluorescence microscopy and fluorescence spectrophotometer; the activities of caspase-8 and 9 were determined by spectrophotometry.The results showed that after the cells were subjected to the pressure for 24 or 36 h,the cell proliferation was inhibited; the ratio of cell apoptosis was increased; the mitochondrial membrane potential was decreased;the activity of caspase-9 was enhanced; no activity changes were observed in caspase-8.The results suggested that treatment with a pressure of 1.1 MPa for more than 24 h can lead to the proliferation inhibition and the apoptosis of rabbit AF cells in vitro,and the mitochondrial-dependent pathway is implicated in the pressure-induced AF cell apoptosis.