Application of a semiautomated contour segmentation tool to identify the intervertebral nucleus pulposus in MR images

Workflow for Segmentation of Caenorhabditis elegans from Fluorescence Images for the Quantitation of Lipids

The small and transparent nematode Caenorhabditis elegans is increasingly employed for phenotypic in vivo chemical screens. The influence of compounds on worm body fat stores can be assayed with Nile red staining and imaging. Segmentation of C. elegans from fluorescence images is hereby a primary task. In this paper, we present an image-processing workflow that includes machine-learning-based segmentation of C. elegans directly from fluorescence images and quantifies their Nile red lipid-derived fluorescence. The segmentation is based on a J48 classifier using pixel entropies and is refined by size-thresholding. The accuracy of segmentation was >90% in our external validation. Binarization with a global threshold set to the brightness of the vehicle control group worms of each experiment allows a robust and reproducible quantification of worm fluorescence. The workflow is available as a script written in the macro language of imageJ, allowing the user additional manual control of classification results and custom specification settings for binarization. Our approach can be easily adapted to the requirements of other fluorescence image-based experiments with C. elegans.

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.

Evaluation of intervertebral disc regeneration with injection of mesenchymal stem cells encapsulated in PEGDA-microcryogel delivery system using quantitative T2 mapping: a study in canines

Intervertebral disc degeneration (IDD), the primary cause of low back pain, is still a great challenge to spinal surgeons and clinicians. T2 mapping, a biochemical magnetic resonance imaging (MRI) technique to calculate relaxation time, has the potential to offer a quantitative assessment of IDD. The aim of the study was to evaluate the regenerative effects of adipose-derived mesenchymal stem cells (MSCs) encapsulated in PEGDA-microcryogels (PMs) reinforced alginate hydrogel (AH) on the degenerative intervertebral disc (IVD) in a canine model using T2 mapping. Four degeneration-induced IVDs (L3-L4 to L6-L7) of 12 adult beagle dogs were injected with phosphate-buffered saline (PBS), MSCs, AH-PMs, and MSCs-laden AH-PMs, respectively. The intact IVD L7-S1 served as the normal control. IVD height change on plain radiograph, Pfirrmann grade and T2 relaxation time on MRI, histological change, and extracellular matrix (ECM)-associated proteins were evaluated during the 24-week follow-up period. Injection of MSCs-laden AH-PMs had the most satisfactory effects, having less decrease of IVD height, lower Pfirrmann grade, milder histological change, and longer T2 relaxation time (P < 0.05). T2 relaxation time was positively correlated with ECM content (proteoglycan: r = 0.85, P < 0.001; collagen II: r = 0.79, P < 0.001) and IVD height (r = 0.81, P < 0.001), but negatively correlated with Pfirrmann grade and histological grade (rho = -0.86, P < 0.001; rho = -0.95, P < 0.001). These results suggest that T2 mapping has the potential to quantitatively evaluate the repairing effects of cell-based engineering treatments on IDD for a long-term follow-up.

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.

PURPOSE

This study aimed to determine the effects of oral indomethacin administration on IDD in an in vivo rabbit model. This study hypothesized that indomethacin use would accelerate the progression of IDD based upon serial imaging and tissue outcomes.

STUDY DESIGN/SETTING

This was a laboratory-based, controlled, in vivo evaluation of the effects of oral indomethacin administration on rabbit intervertebral discs.

METHODS

Six skeletally mature New Zealand white rabbits were divided into two groups: disc puncture alone to induce IDD (Puncture group) and disc puncture plus indomethacin (Punc+Ind group). The Punc+Ind group received daily administration of 6mg/kg oral indomethacin. Serial magnetic resonance imaging (MRI) was obtained at 0, 4, 8, and 12 weeks. The MRI index and the nucleus pulposus (NP) area were calculated. Discs were harvested at 12 weeks for determination of disc glycosaminoglycan (GAG) content, relative gene expression measured by real-time polymerase chain reaction, and histologic analyses.

RESULTS

The MRI index and the NP area of punctured discs in the Punc+Ind group demonstrated no worsening of degeneration compared with the Puncture group. Histologic analysis was consistent with less severe disc degeneration in the Punc+Ind group. Minimal differences in gene expression of matrix genes were observed between Puncture and Punc+Ind groups. The GAG content was higher in animals receiving indomethacin in both annulus fibrosus and NP at adjacent uninjured discs.

CONCLUSIONS

Oral indomethacin administration did not result in acceleration of IDD in an in vivo rabbit model. Future research is needed to ascertain long-term effects of indomethacin and other NSAIDs on disc matrix homeostasis.

Survivin-TGFB3-TIMP1 Gene Therapy Via Lentivirus Vector Slows the Course of Intervertebral Disc Degeneration in an In Vivo Rabbit Model

STUDY DESIGN

The ability of lentivirus vector (LV) survivin-transforming growth factor beta 3 (TGFB3)-tissue inhibitor of metalloproteinases 1 (TIMP1) on slowing disc degeneration was evaluated by an animal experiment.

OBJECTIVE

The aim of the study was to investigate the effect of LV survivin-TGFB3-TIMP1 on slowing disc degeneration in an in vivo rabbit model.

SUMMARY OF BACKGROUND DATA

Cell apoptosis, increase of catabolic activity, and decrease of anabolic activity were the mechanisms of disc degeneration. Meanwhile, survivin, TGFB3, and TIMP1 can influence above process, respectively. However, there were no researches conducted to evaluate the effect of an LV containing all three proteins (referred to as LV-survivin-TGFB3-TIMP1) on slowing disc degeneration in vivo.

METHODS

Twenty skeletally mature female New Zealand White rabbits were randomly divided into four groups: nonpunctured sham surgical group (group A, n = 5), punctured blank control group (group B, n = 5), punctured empty vector control group (group C, n = 5), and the treatment group (group D, n = 5). Computed tomography-guided puncture was performed at the L3-L4 and L4-L5 discs, in accordance with a previously validated rabbit annulotomy model for intervertebral disc degeneration. After 3 weeks, LV-carrying survivin, TGFB3, and TIMP1 were injected into the nucleus pulposus. Serial magnetic resonance imaging studies at 0, 3, and 12 weeks were performed. The rabbits were sacrificed at 12 weeks, and the histology, immunofluorescence, quantitative real-time polymerase chain reaction, Western blot, and caspase-3 activity was used for evaluation.

RESULTS

Magnetic resonance imaging, histology, gene expression, protein content, and apoptosis analyses of group A showed no disc degeneration. Groups B and C showed disc degeneration, which increased over time, and no significant difference was observed between the two groups (P > 0.05). In group D, there was less disc degeneration compared to the punctured control groups and the difference was statistically significant (P < 0.05).

CONCLUSION

The injection of LV-carrying survivin-TGFB3-TIMP1 into punctured rabbit intervertebral discs helps delay degenerative disc changes. Although data from animal models should be extrapolated to the human condition with caution, this study shows promise for gene therapy to decelerate disc degeneration.

LEVEL OF EVIDENCE

N/A.

Associations between serum biomarkers and pain and pain-related function in older adults with low back pain: a pilot study

OBJECTIVES

To examine the relationship between serum biomarkers and self-reported pain intensity and pain-related function, in addition to the contribution of magnetic resonance imaging (MRI) findings of lumbar spine degenerative changes, in older adults with chronic low back pain.

DESIGN

Single-center cross-sectional cohort study.

SETTING

Academic medical center.

PARTICIPANTS

Individuals aged 60 and older with axial low back pain without radiculopathy or previously diagnosed osteoarthritis of the knee or hip or pain outside the low back that is more severe than the back pain (n = 43).

MEASUREMENTS

To examine pain-related impairment, pain was measured on a pain thermometer and the McGill Pain Questionnaire Short Form was administered. To examine pain-related function or activity limitation, the Roland Morris Disability Questionnaire, Short Physical Performance Battery (SPPB), and repetitive trunk rotation were used. Single plasma samples were obtained before and after physical performance tests and analyzed for inflammatory markers (E-selectin and regulated on activation, normal T cell expressed and secreted (RANTES)), inhibitors of catabolic enzymes (tissue inhibitor of metalloproteinases-1 (TIMP-1)), markers of matrix turnover (C- telopeptide of type II collagen (CTX-II) and aggrecan chondroitin sulfate 846 (CS846)), and stress biomarkers (neuropeptide Y (NPY)). Conventional nongadolinium lumbar MRI was performed and analyzed quantitatively and clinically.

RESULTS

Composite MRI measurements did not show significant correlation with pain or pain-related function. Basal levels and changes in serum biomarkers in response to activity, particularly NPY and RANTES, demonstrated associations with pain and pain-related function in addition to the explanatory power of MRI-based results.

CONCLUSION

Serum biomarkers may be a metric for assessment of active disease in older adults, in whom imaging changes are ubiquitous. In addition, changing levels of biomarkers in response to activity suggests that they may be useful as metrics to measure treatment responses in future studies and may reflect potential targets for use in designing personalized treatment for older adults with low back pain.

Correlation of pain with objective quantification of magnetic resonance images in older adults with chronic low back pain

STUDY DESIGN

Cross sectional study.

OBJECTIVE

The goal of this study is to identify relationships between objectively measured and subjectively scored parameters and reported pain.

SUMMARY OF BACKGROUND DATA

Studies have demonstrated the unreliability of magnetic resonance imaging (MRI)-based parameters to identify pathological pain generators of chronic low back pain, but they were based on visual inspection and subjective assessment of lumbar disc features. Advancements in computer image analysis provide objective measurements of lumbar disc features.

METHODS

Two radiologists evaluated 39 axial and sagittal T1- and T2-weighted MR images of patients with chronic axial low back pain (age, >65 yr) and graded 4 subjective lumbar disc parameters (T2 signal intensity, nucleus shape, Modic changes, and osteophyte formation) whose sum is the cumulative MRI score. Objective parameter, MRI index, was calculated as the product of the measured lumbar disc area and total disc MRI signal intensity. Discs were sorted from least to the most degenerated relative to each parameter. Pearson correlation coefficient and multiple linear regression analysis were performed between the reported pain score and each parameter.

RESULTS

The most and least degenerated discs in each patient, as assessed by MRI index, had the highest negative and positive correlation coefficient and regression weight contribution, respectively. All subjective parameters had low correlation coefficients and regression goodness of fit.

CONCLUSION

Although limited by small sample size, the objective parameter, MRI index, can be a potential imaging biomarker used to identify possible pain generators. This study presents a potential new application of MR imaging in identifying pain generators of patients with chronic low back pain.

Quantitative T2 mapping to characterize the process of intervertebral disc degeneration in a rabbit model

BACKGROUND

To investigate the potential of T2 mapping for characterizing the process of intervertebral disc degeneration (IDD) in a rabbit model.

METHODS

Thirty-five rabbits underwent an annular stab to the L4/5 discs (L5/6 discs served as internal normal controls). Degenerative changes were graded according to the modified Thompson classification and quantified in T2 respectively at pre-operation, 1, 3, 6, 12 and 24 weeks postoperatively. After MRI analysis, expression analysis of aggrecan and type II collagen gene in nucleus pulposus (NP) was performed using real time polymerase chain reaction (real-time PCR). The longitudinal changes in NP T2 and gene expressions were studied by repeated measures and ANOVA, linear regression was performed for their correlations through the process of IDD. The reliability analysis of method of measurement of NP T2 was also performed.

RESULTS

There was a strong inverse correlation between NP T2 and Thompson grades (r = -0.85). The decline of L4/5 NP T2 through 24 weeks was nonlinear, the most significant decrease was observed in 3 weeks postoperatively (P<0.05). The tendency was confirmed at gene expression levels. NP T2 correlated strongly with aggrecan (R² = 0.85, P<0.01) and type II collagen (R² = 0.78, P<0.01) gene expressions. The intraclass correlation coefficients for interobserver and intraobserver reliability were 0.963 and 0.977 respectively.

CONCLUSIONS

NP T2 correlates well with aggrecan and type II collagen gene expressions. T2 mapping could act as a sensitive, noninvasive tool for quantitatively characterizing the process of IDD in longitudinal study, help better understanding of the pathophysiology of IDD, assist us to detect the degenerative cascade, and develop a T2-based quantification scale for evaluation of IDD and efficacy of therapeutic interventions.

Glucosamine supplementation demonstrates a negative effect on intervertebral disc matrix in an animal model of disc degeneration

STUDY DESIGN

Laboratory based controlled in vivo study.

OBJECTIVE

To determine the in vivo effects of oral glucosamine sulfate on intervertebral disc degeneration.

SUMMARY OF BACKGROUND DATA

Although glucosamine has demonstrated beneficial effect in articular cartilage, clinical benefit is uncertain. A Centers for Disease Control report from 2009 reported that many patients are using glucosamine supplementation for low back pain, without significant evidence to support its use. Because disc degeneration is a major contributor of low back pain, we explored the effects of glucosamine on disc matrix homeostasis in an animal model of disc degeneration.

METHODS

Eighteen skeletally mature New Zealand White rabbits were divided into 4 groups: control, annular puncture, glucosamine, and annular puncture + glucosamine. Glucosamine treated rabbits received daily oral supplementation with 107 mg/d (weight based equivalent to human 1500 mg/d). Annular puncture surgery involved puncturing the annulus fibrosus of 3 lumbar discs with a 16-gauge needle to induce degeneration. Serial magnetic resonance images were obtained at 0, 4, 8, 12, and 20 weeks. Discs were harvested at 20 weeks for determination of glycosaminoglycan content, relative gene expression measured by real time polymerase chain reaction, and histological analyses.

RESULTS

The magnetic resonance imaging index and nucleus pulposus area of injured discs of glucosamine treated animals with annular puncture was found to be lower than that of degenerated discs from rabbits not supplemented with glucosamine. Consistent with this, decreased glycosaminoglycan was demonstrated in glucosamine fed animals, as determined by both histological and glycosaminoglycan content. Gene expression was consistent with a detrimental effect on matrix.

CONCLUSION

These data demonstrate that the net effect on matrix in an animal model in vivo, as measured by gene expression, magnetic resonance imaging, histology, and total proteoglycan is antianabolic. This raises concern about this commonly used supplement, and future research is needed to establish the clinical relevance of these findings.

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

BACKGROUND CONTEXT

Patients 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.

PURPOSE

To determine whether injecting human umbilical tissue-derived cells (hUTC) into the nucleus pulposus (NP) might improve the course of IDD.

DESIGN

Prospective, randomized, blinded placebo-controlled in vivo study.

PATIENT SAMPLE

Skeletally mature New Zealand white rabbits.

OUTCOME MEASURES

Degree of IDD based on magnetic resonance imaging (MRI), biomechanics, and histology.

METHODS

Thirty 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.

RESULTS

Qualitatively, 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.

CONCLUSIONS

Treatment 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.

Injection of AAV2-BMP2 and AAV2-TIMP1 into the nucleus pulposus slows the course of intervertebral disc degeneration in an in vivo rabbit model

BACKGROUND CONTEXT

Intervertebral disc degeneration (IDD) is a common cause of back pain. Patients who fail conservative management may face the morbidity of surgery. Alternative treatment modalities could have a significant impact on disease progression and patients' quality of life.

PURPOSE

To determine if the injection of a virus vector carrying a therapeutic gene directly into the nucleus pulposus improves the course of IDD.

STUDY DESIGN

Prospective randomized controlled animal study.

METHODS

Thirty-four skeletally mature New Zealand white rabbits were used. In the treatment group, L2-L3, L3-L4, and L4-L5 discs were punctured in accordance with a previously validated rabbit annulotomy model for IDD and then subsequently treated with adeno-associated virus serotype 2 (AAV2) vector carrying genes for either bone morphogenetic protein 2 (BMP2) or tissue inhibitor of metalloproteinase 1 (TIMP1). A nonoperative control group, nonpunctured sham surgical group, and punctured control group were also evaluated. Serial magnetic resonance imaging (MRI) studies at 0, 6, and 12 weeks were obtained, and a validated MRI analysis program was used to quantify degeneration. The rabbits were sacrificed at 12 weeks, and L4-L5 discs were analyzed histologically. Viscoelastic properties of the L3-L4 discs were analyzed using uniaxial load-normalized displacement testing. Creep curves were mathematically modeled according to a previously validated two-phase exponential model. Serum samples obtained at 0, 6, and 12 weeks were assayed for biochemical evidence of degeneration.

RESULTS

The punctured group demonstrated MRI and histologic evidence of degeneration as expected. The treatment groups demonstrated less MRI and histologic evidence of degeneration than the punctured group. The serum biochemical marker C-telopeptide of collagen type II increased rapidly in the punctured group, but the treated groups returned to control values by 12 weeks. The treatment groups demonstrated several viscoelastic properties that were distinct from control and punctured values.

CONCLUSIONS

Treatment of punctured rabbit intervertebral discs with AAV2-BMP2 or AAV2-TIMP1 helps delay degenerative changes, as seen on MRI, histologic sampling, serum biochemical analysis, and biomechanical testing. Although data from animal models should be extrapolated to the human condition with caution, this study supports the potential use of gene therapy for the treatment of IDD.