阻断双侧终板营养途径构建山羊椎间盘退变模型

目的通过建立山羊腰椎双侧终板营养途径阻断的动物模型,观察椎间盘退变(IDD)的情况,研究椎间盘营养途径与IDD的相关性。方法选取8只24月龄雌性关中山羊,每只山羊L2~3、L3~4作为实验椎间盘,麻醉后在平行于终板2 mm的椎体骨质处造成骨缺损,并使用骨水泥填塞,阻断椎体和终板之间的营养通路,L1~2、L4~5作为对照椎间盘。分别于术后4、12、24、48周行X线、MRI检查,各时间点随机处死2只山羊,采集椎间盘标本,计算骨水泥有效阻断面积、椎间高度指数(DHI)和Pfirrmann分级,并行HE、Masson三色、蛋白多糖、番红O染色组织学检查。结果术后骨水泥有效阻断面积达49.6%~69.6%(60.7%±5.3%)。术后48周时实验椎间盘DHI百分比为60.5%~81.7%(72.7%±5.6%),椎间高度丢失较对照差异有统计学意义(P<0.01);术后48周时实验椎间盘Pfirrmann分级为3~5(4.0±0.7)分,较对照差异有统计学意义(P<0.01)。组织学检查证实,实验椎间盘术后12周即发生退变,并随时间(24、48周)逐步加重。结论骨水泥填塞阻断双侧终板营养途径可以构建山羊IDD的动物模型,阻断终板营养途径可以导致IDD发生。     

Interference in the endplate nutritional pathway causes intervertebral disc degeneration in an immature porcine model

Purpose

Previous studies have shown that blocking the endplate nutritional pathway with bone cement did not result in obvious intervertebral disc degeneration (IDD) in mature animal models. However, there are very few comparable studies in immature animal models. As vertebroplasty currently is beginning to be applied in young, even biologically immature patients, it is important to investigate the effect of cement blocking at the endplate in an immature animal model.

Methods

Two lumbar intervertebral discs in eight immature pigs were either blocked by cement in both endplate pathways or stabbed with a scalpel in the annulus fibrosus (AF) as a positive control, and with a third disc remaining intact as a normal control. Magnetic resonance imaging (MRI) and histology study were performed.

Results

After three months, the cement-blocked discs exhibited severe IDD, with the percentage of disc-height index (DHI), nucleus pulposus (NP) area, and NP T2 value significantly lower than the normal control. These IDD changes were histologically confirmed. Post-contrast MRI showed diseased nutritional diffusion patterns in the cement-blocked discs. Moreover, the degenerative changes of the cement-blocked discs exceeded those of the injured AF positive controls.

Conclusions

The endplate nutritional pathway was interfered with and diseased after three months of bone cement intervention in an immature porcine model. Severe interference in the endplate nutritional pathway in an immature porcine model caused IDD. These findings also draw attention to the fact that interference in endplate nutritional pathways in immature or young patients may affect the vitality of adjacent discs.     

退变椎间盘聚集蛋白聚糖中硫酸软骨素链变化的实验研究

目的：研究内破裂及突出椎间盘细胞合成的聚集蛋白聚糖中硫酸软骨素链（CS）在长度及数量分布上的变化.方法：将正常椎间盘、内破裂（IDD）及突出椎间盘（LIDP）髓核或纤维环的组织20mg培养于24孔板中,用放射性同位素35S-硫酸盐和3H-丝氨酸标记新合成的蛋白聚糖分子.将聚集蛋白聚糖单体从培养的组织片中提取,用四氢硼酸钠或木瓜蛋白酶消化后,凝胶包谱分析硫酸软骨链的变化特征.结果：IDD椎间盘组织内细胞合成的聚集蛋白聚糖内CS链的数量明显减少,但长度保持相对正常;突出椎间盘组织中CS的数量和长度有明显下降和缩短,CS链数量的减少较IDD组织中更为严重.结论：IDD组织合成CS的减少主要是由于生成的CS链数量减少所致,而数量的进一步减少以及CS链长度的缩短是LIDP组织中CS合成量下降的主要原因.     

Three-dimensional microstructural reconstruction of the ovine intervertebral disc using ultrahigh field MRI

BACKGROUND

The intervertebral disc (IVD) is a complex organ that acts as a flexible coupling between two adjacent vertebral bodies and must therefore accommodate compression, bending, and torsion. It consists of three main components, which are elegantly structured to allow this: the annulus fibrosus (AF), the nucleus pulposus (NP), and the end-plates (EP).

NSAID use in intervertebral disc degeneration: what are the effects on matrix homeostasis in vivo?

Background Context

Non-steroidal anti-inflammatory drugs (NSAIDs) are a widely used treatment for low back pain (LBP). Literature on NSAID use in articular cartilage has shown detrimental effects; however, minimal data exist to detail the effects of NSAIDs in intervertebral disc degeneration (IDD). As IDD is a major cause of LBP, we explored the effects of indomethacin, a commonly used NSAID, on disc matrix homeostasis in an animal model of IDD.

Identification of intervertebral disc regeneration with magnetic resonance imaging after a long-term follow-up in patients treated with percutaneous diode laser nucleoplasty: a retrospective clinical and radiological analysis of 14 patients

Purpose

The aim of this study was to demonstrate regeneration of intervertebral discs undergoing laser therapy with sagittal relaxation time (T2) mapping after a long-term follow-up.

Materials and methods

Fourteen patients (9 men, 5 women; age range 20–57 years; mean age 36.5 years) treated with percutaneous 908-nm wave-length diode laser nucleoplasty for lumbar disc prolapsus at our clinic between January 2006 and June 2009 were studied. For the application of laser nucleoplasty in the past, patients who did not have central canal stenosis and/or lateral stenosis, sequestered disc fragment, operation scars and bleeding disorders were selected. The intervertebral disc levels undergoing laser therapy were L3–L4 (n = 2) or L4–L5 (n = 12). Patients were called for follow-up visits after a maximum 6-years (n = 2) or a minimum 3 years (n = 3) with a mean of 4.4 years. The patients’ clinical status for leg pain was evaluated according to the visual analog scale (VAS) and subsequently, a lumbar magnetic resonance imaging was performed. Sagittal T2 mapping was performed for the intervertebral discs undergoing laser nucleoplasty. We analyzed the relationship between T2 in the regions of interest (ROIs), which is known to correlate with changes in the composition of intervertebral discs, and the degree of degeneration determined using the Pfirrmann grading system and VAS of patients.

Results

On the basis of the evaluation of the results of intervertebral discs in all patients, there was a significant increase in T2 in the anterior NP (ROI 2, +10.3 ms; p < 0.05). A significant increase was noted in T2 in the middle NP (ROI 3, +24.6 ms; p < 0.001). The most significant increase was recorded for the posterior NP (ROI 4, +28.6 ms; p < 0.001). No significant decrease was found in T2 in the anterior and posterior AF (ROI 1, ?1.5 ms; p = 0.925; ROI 5, ?0.1 ms; p = 0.683). According to the Pfirrmann grading system, disc degeneration grades before laser therapy were recorded as grade III (n = 6) and grade IV (n = 8) whereas disc degeneration grades after laser therapy were found to be grade I (n = 6) and II (n = 8). A significant decrease was noted in Pfirrmann grades of disc degeneration after laser therapy (p < 0.0005).

Conclusions

In this study, there was a prolongation of T2 indicating regeneration in the nucleus pulposus after laser therapy and these results were found to be consistent with VAS measurements after a long-term follow-up. This study, which demonstrates the quantitative efficacy of laser therapy, indicates that MRG can be more effectively used in the future.     

Injection of human umbilical tissue–derived cells into the nucleus pulposus alters the course of intervertebral disc degeneration in vivo

Background contextPatients often present to spine clinic with evidence of intervertebral disc degeneration (IDD). If conservative management fails, a safe and effective injection directly into the disc might be preferable to the risks and morbidity of surgery.PurposeTo determine whether injecting human umbilical tissue–derived cells (hUTC) into the nucleus pulposus (NP) might improve the course of IDD.DesignProspective, randomized, blinded placebo–controlled in vivo study.Patient sampleSkeletally mature New Zealand white rabbits.Outcome measuresDegree of IDD based on magnetic resonance imaging (MRI), biomechanics, and histology.MethodsThirty skeletally mature New Zealand white rabbits were used in a previously validated rabbit annulotomy model for IDD. Discs L2–L3, L3–L4, and L4–L5 were surgically exposed and punctured to induce degeneration and then 3 weeks later the same discs were injected with hUTC with or without a hydrogel carrier. Serial MRIs obtained at 0, 3, 6, and 12 weeks were analyzed for evidence of degeneration qualitatively and quantitatively via NP area and MRI Index. The rabbits were sacrificed at 12 weeks and discs L4–L5 were analyzed histologically. The L3–L4 discs were fixed to a robotic arm and subjected to uniaxial compression, and viscoelastic displacement curves were generated.ResultsQualitatively, the MRIs demonstrated no evidence of degeneration in the control group over the course of 12 weeks. The punctured group yielded MRIs with the evidence of disc height loss and darkening, suggestive of degeneration. The three treatment groups (cells alone, carrier alone, or cells+carrier) generated MRIs with less qualitative evidence of degeneration than the punctured group. MRI Index and area for the cell and the cell+carrier groups were significantly distinct from the punctured group at 12 weeks. The carrier group generated MRI data that fell between control and punctured values but failed to reach a statistically significant difference from the punctured values. There were no statistically significant MRI differences among the three treatment groups. The treated groups also demonstrated viscoelastic properties that were distinct from the control and punctured values, with the cell curve more similar to the punctured curve and the carrier curve and carrier+cells curve more similar to the control curve (although no creep differences achieved statistical significance). There was some histological evidence of improved cellularity and disc architecture in the treated discs compared with the punctured discs.ConclusionsTreatment of degenerating rabbit intervertebral discs with hUTC in a hydrogel carrier solution might help restore the MRI, histological, and biomechanical properties toward those of nondegenerated controls. Treatment with cells in saline or a hydrogel carrier devoid of cells also might help restore some imaging, architectural, and physical properties to the degenerating disc. These data support the potential use of therapeutic cells in the treatment of disc degeneration.     

Apoptosis,senescence, and autophagy in rat nucleus pulposus cells: Implications for diabetic intervertebral disc degeneration

This research was aimed to study the mechanisms by which diabetes aggravates intervertebral disc degeneration (IDD) and to discuss the relationship between autophagy and IDD in nucleus pulposus (NP) cells. Sixteen weeks after injecting streptozotocin (STZ), the intervertebral discs (IVDs) were studied by histology, Alcian blue, 1,9‐dimethylmethylene blue (DMMB), immunohistochemistry, and RT‐PCR to explore the IDD. The apoptosis and senescence of NP cells was investigated by terminal deoxyribonucleotidyl transferase (TDT)‐mediated dUTP‐digoxigenin nick end labeling (TUNEL) assay, immunohistochemistry, and Western blot for caspase3, caspase8, caspase9, and p16lnk4A (increased in cellular senescence). The level of autophagy in NP cells was detected by Western blot, immunohistochemistry, and transmission electron microscopy (TEM). The proteoglycan and collagen II in the extracellular matrix and the aggrecan and collagen II mRNA expression in NP cells of diabetic rats were decreased compared with the control group. Diabetes increased apoptosis of NP cells and led to activations of initiators of intrinsic (caspases‐9) and extrinsic (caspase‐8) pathways as well as their common executioner (caspase‐3). Cellular senescence was increased about twofold in NP of diabetic rats. In addition, the Western blot, immunohistochemistry, and TEM demonstrated higher level of autophagy in NP cells of diabetic rats than control rats to a statistically significant extent. These findings support that diabetes induced by STZ can cause IDD by accelerating the apoptosis and senescence of NP cells excluding the overweight influence. And the results suggest that the autophagy may be a response mechanism to the change of NP cells in diabetic rats. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 692–702, 2013     

Role of miR‐155 in the regulation of MMP‐16 expression in intervertebral disc degeneration

The molecular mechanisms of intervertebral disc degeneration (IDD) remain elusive. We found that miR‐155 is down‐regulated in degenerative nucleus pulposus (NP), and more severe degeneration is correlated with higher matrix metallopeptidase 16 (MMP‐16) expression. MMP‐16 also degraded matrix aggrecan. Here, we addressed the in vivo miR‐155‐mediated pathological impact on IDD using a classic puncture mouse model. Lentiviral upregulated‐miR‐155 or downregulated‐miR‐155 was transduced into the discs of C57 mice, which was validated by real‐time polymerase chain reaction (real‐time PCR) and in situ hybridization. Immunohistochemistry and western blotting revealed that up‐regulation of miR‐155 resulted in down‐regulation of MMP‐16 and an increase in aggrecan and collagen type II in mouse NP; whereas, down‐regulation of miR‐155 resulted in up‐regulation of MMP‐16 and a decrease in aggrecan in mouse NP. Radiographic and histological analysis showed that the up‐regulation of miR‐155 attenuated IDD, while down‐regulation of miR‐155 resulted in the deterioration of IDD. These findings indicate that decreased miR‐155 contributed to the up‐regulation of MMP‐16 in vivo, and MMP‐16 further degraded aggrecan and collagen type II, leading to the dehydration and degeneration of discs. Our findings revealed a therapeutic role for miR‐155 in IDD. © 2017 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1323–1334, 2017.

     

MRI evaluation of spontaneous intervertebral disc degeneration in the alpaca cervical spine

Animal models have historically provided an appropriate benchmark for understanding human pathology, treatment, and healing, but few animals are known to naturally develop intervertebral disc degeneration. The study of degenerative disc disease and its treatment would greatly benefit from a more comprehensive, and comparable animal model. Alpacas have recently been presented as a potential large animal model of intervertebral disc degeneration due to similarities in spinal posture, disc size, biomechanical flexibility, and natural disc pathology. This research further investigated alpacas by determining the prevalence of intervertebral disc degeneration among an aging alpaca population. Twenty healthy female alpacas comprised two age subgroups (5 young: 2–6 years; and 15 older: 10+ years) and were rated according to the Pfirrmann‐grade for degeneration of the cervical intervertebral discs. Incidence rates of degeneration showed strong correlations with age and spinal level: younger alpacas were nearly immune to developing disc degeneration, and in older animals, disc degeneration had an increased incidence rate and severity at lower cervical levels. Advanced disc degeneration was present in at least one of the cervical intervertebral discs of 47% of the older alpacas, and it was most common at the two lowest cervical intervertebral discs. The prevalence of intervertebral disc degeneration encourages further investigation and application of the lower cervical spine of alpacas and similar camelids as a large animal model of intervertebral disc degeneration. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1776–1783, 2015.     

The presence and distribution of lubricin in the caprine intervertebral disc

Lubricin is a large, multifunctional glycoprotein that is known to play a role as a boundary lubricant in diarthrodial joint articulation. The hypothesis of this study was that lubricin is present in the intervertebral disc in a distribution consistent with serving to facilitate interlamellar tribology. The objectives were to: (1) determine the distribution of lubricin in the normal caprine disc; and (2) investigate the synthesis of lubricin by caprine annulus fibrosus (AF) and nucleus pulposus (NP) cells in vitro, using immunohistochemical methods. Caprine lumbar intervertebral discs from five levels and four animals were studied. Positive staining revealed the presence of the lubricin in the outer AF of nearly all samples. No staining was present in the inner AF or the NP. Within the outer AF, lubricin was prominent in the layers separating lamellae and in the extracellular matrix of the lamellae. Some of the AF cells within the lubricin‐positive regions demonstrated intracellular lubricin staining, suggesting that these cells may be synthesizing the lubricin protein observed. Immunohistochemistry performed on monolayer cultures of primary AF and NP cells demonstrated intracellular lubricin staining in both cell types. Thus, lubricin is selectively present in the outer caprine intervertebral disc AF, and its distribution suggests that it may play a role in interlamellar tribology. Cells from both the annulus and nucleus were found capable of synthesizing lubricin in vitro, suggesting that these cells may be a potential source of the glycoprotein under some conditions. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1398–1406, 2008     

Intervertebral disc degeneration and ectopic bone formation in apolipoprotein E knockout mice

Cardiovascular risk factors are known to be associated with intervertebral disc degeneration, but the underlying mechanism is still unclear. The ApoE knockout (KO) mouse is a well‐established model for atheroscelorosis. We hypothesized that ApoE is involved in maintaining disc health and that ApoE KO mice will develop early disc degeneration. Discs of ApoE KO and wild‐type (WT) mice were characterized with histological/immunological, biochemical, and real‐time RT‐PCR assays. A comparison of the extracellular matrix production was also performed in disc cells. We demonstrated that ApoE was highly expressed in the endplates of WT discs, and ectopic bone formed in the endplates of ApoE KO discs. Glycosaminoglycan content was decreased in both ApoE KO annulus fibrosus (AF) and nucleus pulposus (NP) cells. Collagen levels were increased in AF and decreased in NP cells. Matrix metalloproteinase‐3, ‐9, and ‐13 expressions were increased, which may partially explain the impaired matrix production. We also found collagen I, II, aggrecan, and biglycan mRNA expressions were increased in AF cells but decreased in NP cells. Apoptosis was increased in the ApoE KO NP tissue. These results suggest early disc degeneration changes in the ApoE KO mice. ApoE may play a critical role in disc integrity and function. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 210–217, 2013     

围绝经期女性腰椎椎间盘退变程度的MRI观察

目的探讨围绝经期女性腰椎椎间盘MRI特点及相关退变规律。方法随机选择2014年1月—12月来本院就诊的成年男女患者各420例,记录患者年龄、身高、体质量指数(BMI)、吸烟史、高血压史、糖尿病史、月经史、职业等,每位患者均行腰椎MRI检查。女性患者按照月经史分为5个组:绝经前组(n=76),绝经0年且6年组(n=98),绝经≥6年且11年组(n=82),绝经≥11年且≤15年组(n=80),绝经15年组(n=84)。用Pfirrmann分级系统对腰椎椎间盘退变程度进行分级,用SPSS 19.0软件进行相关数据分析。结果男女患者年龄、BMI、糖尿病史、高血压史、职业等差异无统计学意义(P0.05);男性吸烟率明显高于女性,差异有统计学意义(P0.05)。男性患者Pfirrmann分级≥Ⅲ级的椎间盘比例高于女性(男78.2%,女60.8%),差异有统计学意义(P0.05);PfirrmannⅣ、Ⅴ级时差异更显著。在女性亚组中,绝经前组各椎间盘水平Pfirrmann平均分均显著低于各绝经组,差异有统计学意义(P0.05)。绝经≤15年时,绝经年限越高,L_1/L_2、L_2/L_3、L_4/L_5及L_5/S_1椎间盘Pfirrmann平均分越高,差异有统计学意义(P0.05);绝经≥11年且≤15年组与绝经15年组间各节段椎间盘Pfirrmann平均分差异均无统计学意义(P0.05)。结论男性患者腰椎椎间盘退变较女性严重。绝经后女性腰椎椎间盘退变较绝经前严重,且在绝经≤15年时,绝经年限越长,退变越严重;绝经15年后,腰椎椎间盘退变进程减缓。因此,雌激素水平下降可能是腰椎椎间盘退变的危险因素。     

Asymmetry between the superior and inferior endplates is a risk factor for lumbar disc degeneration

Endplate pathology plays an important role in the development of lumbar disc degeneration. Previous research paid little attention to differences between the superior and inferior endplates as a possible risk factor for disc degeneration. The purpose of this study was to test the hypothesis that asymmetry between the superior and inferior endplates is a risk factor for the development of lumbar disc degeneration. A total of 134 patients with lumbar disc herniation (LDH) and 100 healthy adults (“Controls”) underwent magnetic resonance imaging scans. Each disc was categorized as non‐degenerated (Pfirrmann grades I–II) or degenerated (Pfirrmann grades III–V) and get the following three groups: “Degenerated LDH” discs (n = 145), “Non‐degenerated LDH” discs (n = 525) and “Non‐degenerated Control” discs (n = 500). On mid‐sagittal image, the lumbar endplate morphology could be categorized into three types: Flat, concave, and irregular. Superior and inferior endplates of a given disc were “symmetric” if both were of the same type, and “asymmetric” if they were of different types. The proportion of asymmetric endplates at L4–5 was higher in the “Degenerated LDH” discs group (47%) than in the “Non‐degenerated LDH” discs group (21%) or “Non‐degenerated Control” discs group (7%) (p < 0.05). At L5‐S1 the proportions were 73%, 55%, and 38% (p < 0.05). Asymmetry of superior and inferior endplates in the mid‐sagittal plane is a risk factor for lumbar disc degeneration. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2469–2475, 2018.

     

Disc degeneration contributes to the denser bone in the subendplate but not in the vertebral body in patients with lumbar spinal stenosis or disc herniation

BACKGROUND CONTEXTIt is commonly believed that decreased bone quality would lead to endplate degeneration and arthritic changes in the facet joints, and thus accelerated disc degeneration (DD). However, some more detailed studies of vertebral bone structure have found that bone mineral density (BMD) in the vertebral body is increased rather than decreased in moderate or greater disc degeneration. The relationship between BMD and DD still needs further study. MRI-based vertebral bone quality scores have been shown to be effective in reflecting BMD, rendering a new way to evaluate the changes of vertebral body bone with DD using MRI alone.PURPOSETo evaluate MRI-based vertebral bone quality and Pfirrmann grades in patients with lumbar spinal stenosis or disc herniation, and to identify if DD is associated with denser bone around the endplate.STUDY DESIGN/SETTINGA single-center, retrospective cohort study.PATIENT SAMPLEA total of 130 patients with lumbar disc herniation and lumbar spinal stenosis from January 2019 to November 2020 who had a complete dual-energy X-ray absorptiometry scan and noncontrast lumbosacral spine MRI data.OUTCOME MEASURESThe vertebral bone quality score (VBQ) and sub-endplate bone quality score (EBQ) was calculated as a ratio of the signal intensity of the vertebral bodies and sub-endplate regions to the signal intensity of the cerebrospinal fluid at L3 on the mid-sagittal T1-weighted MRI images, respectively. The Pfirrmann grades of the lumbar discs were assessed as well.METHODSThe age, gender, body mass index, and T-score of the lumbar spine of the patients were collected. The degeneration grades of the lumbar discs were evaluated according to the Pfirrmann classification. VBQ and EBQ were measured through T1-weighted lumbar MRI. The VBQ and EBQ scores were compared between cranial and caudal sides. The correlation between MRI-based bone quality and DD was calculated. A linear regression model was used to examine the association between DD and adjacent EBQ and VBQ.RESULTSThis study included 569 lumbar segments from 130 inpatients. Cranial and caudal EBQ decreased with the increase of the Pfirrmann grade. The discs with Pfirrmann grade 5 had significantly lower caudal EBQ than the discs with Pfirrmann grades 2, 3, and 4. In the osteoporosis patients, the Pfirrmann grades negatively correlated both with the cranial EBQ and caudal EBQ. Pfirrmann grade greater than 4 was an independent contributor to the cranial EBQ, whereas greater than 3 was an independent contributor to the caudal EBQ.CONCLUSIONSDisc degeneration grades correlated with the EBQ but not with the VBQ. In patients with lumbar spinal stenosis or disc herniation, DD contributes to the denser bone in the sub-endplate, but not in the whole vertebral body.     

Bone morphogenic protein-2 signaling in human disc degeneration and correlation to the Pfirrmann MRI grading system

BACKGROUND CONTEXTBack and neck pain secondary to disc degeneration is a major public health burden. There is a need for therapeutic treatments to restore intervertebral disc (IVD) composition and function.PURPOSETo quantify ALK3, BMP-2, pSMAD1/5/8 and MMP-13 expression in IVD specimens collected from patients undergoing surgery for disc degeneration, to correlate ALK3, BMP-2, pSMAD1/5/8 and MMP-13 expression in IVD specimens to the 5-level Pfirrmann MRI grading system, and to compare ALK3, BMP-2, pSMAD1/5/8 and MMP-13 expression between cervical and lumbar degenerative disc specimens.STUDY DESIGNAn immunohistochemical study assessing ALK3, BMP-2, pSMAD1/5/8, and MMP-13 expression levels in human control and degenerative IVD specimens.METHODSHuman IVD specimens were collected from surgical patients who underwent discectomy and interbody fusion at our institution between 1/2015 and 8/2017. Each patient underwent MRI prior to surgery. The degree of disc degeneration was measured according to the 5-level Pfirrmann MRI grading system. Patients were categorized into either the 1) control group (Pfirrmann grades I-II) or 2) degenerative group (Pfirrmann grades III-V). Histology slides of the collected IVD specimens were prepared and immunohistochemical staining was performed to assess ALK3, BMP-2, pSMAD1/5/8, and MMP-13 expression levels in the control and degenerative specimens. Expression levels were also correlated to the Pfirrmann criteria. Lastly, the degenerative specimens were stratified according to their vertebral level and expression levels between the degenerative lumbar and cervical discs were compared.RESULTSFifty-two patients were enrolled; however, 2 control and 2 degenerative patients were excluded due to incomplete data sets. Of the remaining 48 patients, there were 12 control and 36 degenerative specimens. Degenerative specimens had increased expression levels of BMP-2 (p=.0006) and pSMAD1/5/8 (p<.0001). Pfirrmann grade 3 (p=.0365) and grade 4 (p=.0008) discs had significantly higher BMP-2 expression as compared to grade 2 discs. Pfirrmann grade 4 discs had higher pSMAD1/5/8 expression as compared to grade 2 discs (p<.0001). There were no differences in ALK3 or MMP-13 expression between the control and degenerative discs (p>.05). Stratifying the degenerative specimens according to their vertebral level showed no significant differences in expression levels between the lumbar and cervical discs (p>.05).CONCLUSIONSBMP-2 and pSMAD1/5/8 signaling activity was significantly upregulated in the human degenerative specimens, while ALK3 and MMP-13 expression were not significantly changed. The expression levels of BMP-2 and pSMAD1/5/8 correlate positively with the degree of disc degeneration measured according to the Pfirrmann MRI grading system.CLINICAL SIGNIFICANCEBMP-SMAD signaling represents a promising therapeutic target to restore IVD composition and function in the setting of disc degeneration.     

Value of delayed gadolinium‐enhanced magnetic resonance imaging of cartilage for the pre‐operative assessment of cervical intervertebral discs

The study was performed to preoperatively assess the cartilage integrity of cervical intervertebral discs (IVDs) using Delayed Gadolinium‐Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC). Therefore, 53 cervical intervertebral discs of nine preoperative patients with neck and shoulder/arm pain scheduled for discectomy (five females, four males; mean age: 47.1 ± 8.4 years; range: 36–58 years) were included for biochemical analysis in this retrospective study. The patients underwent 3T magnetic resonance imaging (MRI) including biochemical imaging with dGEMRIC and morphological, sagittal T2 weighted (T2w) imaging. Cervical IVDs were rated using an MRI based grading system for cervical IVDs on T2w images. Region‐of‐interest measurements were performed in the nucleus pulposus (NP) and annulus fibrosus (AF) and a dGEMRIC index was calculated. Our results demonstrated that IVDs scheduled for discectomy showed significantly lower dGEMRIC index compared to IVDs that did not require surgical intervention in NP and AF (NP: 898.4 ± 191.9 ms vs. 1,150.3 ± 320.7 ms, p = 0.008; AF: 738.7 ± 183.8 ms vs. 984.6 ± 178.9 ms, p = 0.008). For Miyazaki score 3, the dGEMRIC indices were significantly lower in IVDs scheduled for surgery compared to non‐operated discs for NP (p = 0.043) and AF (p = 0.018). In conclusion we could demonstrate that biochemical imaging with dGEMRIC is feasible in cervical IVDs. Significantly lower dGEMRIC index suggested GAG depletion in degenerated cervical IVD, scheduled for discectomy. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1824–1830, 2017.

     

Photopolymerizable biogel scaffold seeded with mesenchymal stem cells: safety and efficacy evaluation of novel treatment for intervertebral disc degeneration

Tissue engineering approaches to treatment of intervertebral disc degeneration (IDD) represent a novel avenue of addressing the biologic basis of this disease. However, such approaches remain limited by their invasive nature and disruption to the annular fibrosis (AF). This study sought to explore a new minimally‐invasive tissue‐engineering approach utilizing an injection of a photopolymerizable biogel scaffold seeded with mesenchymal stem cells (MSCs) directly into the nucleus pulposus (NP). This study was performed using rabbit specimens for both in vivo and in vitro outcome measures. The treatment in this study was performed by injecting 25 μl of 10% (w/v) methacrylated gelatin biogel with 0.15% (w/v) lithium phenyl 2,4,6‐trimethylbenzoylphosphinate (LAP) and rabbit MSCs (1 × 10⁶) cells/ml into the NP. Samples were then photopolymerized in situ using non‐ultraviolet light irradiation via a fiberoptic wire. For the in vitro arm of this study, gene expression analysis demonstrated increased anabolic activity in irradiated MSCs with and without biogel scaffolds. For the in vivo arm of this study, while GAG analysis did not demonstrate significant differences between groups, MRI analysis exhibited a trend toward improved NP matrix. Histological analysis was consistent with increased cellularity and less severe disc degeneration in the MSC + Gel group. However, osteophyte formation was noted in both Stab and MSC + Gel groups after the study period. Increased matrix gene expression of irradiated groups within in vitro studies indicates a photobiologic effect of 405 nm light. Despite promising anabolic actions, osteophyte formation and AF defects could not be avoided with implementation of this minimally‐invasive tissue‐engineering approach. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1451–1459, 2019.     

Alterations of ADAMTSs and TIMP‐3 in human nucleus pulposus cells subjected to compressive load: Implications in the pathogenesis of human intervertebral disc degeneration

Intervertebral disc degeneration (IDD) pertains to the loss of extracellular matrix (ECM), particularly the early loss of aggrecan, the turnover of which is regulated by ADAMTSs. Amongst the etiological factors of IDD, mechanical stress plays an important role in the physiological and pathological processes of nucleus pulposus (NP) cells. However, the role of ADAMTSs and their inhibitor in human NP cells under mechanical stress has not been elucidated to date. The purpose of this study was to investigate the role of ADAMTSs and TIMP‐3 in NP cells under mechanical stress. Human NP cells isolated from non‐degenerative and degenerative discs were subjected to dynamic compressive load. The expression of ADAMTSs, aggrecan, and TIMP‐3 was detected by quantitative real‐time PCR and/or Western blot. Consequently, the gene expression of ADAMTS‐1, 4, and 5 increased significantly in loaded NP cells compared with not‐loaded cells from either non‐degenerative or degenerative discs, whereas the gene expression of aggrecan decreased significantly. Moreover, Western blot indicated increased protein levels of ADAMTSs‐1, 4, and 5. However, the expression of TIMP‐3 altered insignificantly. Together, this study is the first addressing the underlying mechanisms of compressive load as a contributing factor to IDD in terms of ADAMTSs. Our results suggest that compressive load leads to the increase in ADAMTS‐1, 4, and 5 that contributes to the decrease of aggrecan and IDD via TIMP‐3 independent machinery. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:267–273, 2012