Sangwook Tim Yoon

ISSLS Prize Winner : LMP-1 Upregulates Intervertebral Disc Cell Production of Proteoglycans and BMPs In Vitro and In Vivo

Study Design. Experiments using both in vitro tissue culture and in vivo rabbit methods were used to study the effect of Lim Mineralization Protein-1 (LMP-1) on intervertebral disc (IVD) cell production of proteoglycans and bone morphogenetic proteins (BMPs). Objectives. To determine the effect of LMP-1 overexpression in IVD cells on the production of proteoglycans and BMPs both in vitro and in vivo and to show that LMP-1 mediates the control of proteoglycan production through its action on BMPs. Summary of Background Data. Because BMPs are known to increase proteoglycan synthesis and LMP-1 is known to upregulate BMPs in certain cells, it was hypothesized that LMP-1 may increase proteoglycan production in IVD cells. Methods. DMMB, real-time polymerase chain reaction, and ELISA methods were used to quantitate proteoglycan, mRNA, and protein levels, respectively. Noggin was used to block the effect of the adenovirus carrying LMP-1 (AdLMP-1) on proteoglycan synthesis. In vivo experiments using intradiscal AdLMP-1 injection were performed with New Zealand White rabbits. Three weeks later, the mRNA levels of LMP-1, aggrecan, BMP-2, and BMP-7 were measured. Results. In vitro experiments revealed that the sulfated glycosaminoglycan (sGAG) and aggrecan mRNA levels were significantly increased with AdLMP-1 treatment. Similarly, BMP-2 and BMP-7 mRNA and protein levels increased significantly, but BMP-4 and BMP-6 levels were unchanged. Noggin blocked the upregulation of proteoglycan by AdLMP-1. In vivo discs injected with AdLMP-1 had significantly elevated levels of LMP-1, BMP-2, and BMP-7 mRNA. Conclusions. LMP-1 overexpression increases disc cellproduction of proteoglycan, BMP-2, and BMP-7. LMP-1mediates the control of proteoglycan production through its action on BMP.

Efficacy and safety of surgical decompression in patients with cervical spondylotic myelopathy: results of the AOSpine North America prospective multi-center study.

BACKGROUND Cervical spondylotic myelopathy is the leading cause of spinal cord dysfunction worldwide. The objective of this study was to evaluate the impact of surgical decompression on functional, quality-of-life, and disability outcomes at one year after surgery in a large cohort of patients with this condition. METHODS Adult patients with symptomatic cervical spondylotic myelopathy and magnetic resonance imaging evidence of spinal cord compression were enrolled at twelve North American centers from 2005 to 2007. At enrollment, the myelopathy was categorized as mild (modified Japanese Orthopaedic Association [mJOA] score ≥ 15), moderate (mJOA = 12 to 14), or severe (mJOA < 12). Patients were followed prospectively for one year, at which point the outcomes of interest included the mJOA score, Nurick grade, Neck Disability Index (NDI), and Short Form-36 version 2 (SF-36v2). All outcomes at one year were compared with the preoperative values with use of univariate paired statistics. Outcomes were also compared among the severity classes with use of one-way analysis of variance. Finally, a multivariate analysis that adjusted for baseline differences among the severity groups was performed. Treatment-related complication data were collected and the overall complication rate was calculated. RESULTS Eighty-five (30.6%) of the 278 enrolled patients had mild cervical spondylotic myelopathy, 110 (39.6%) had moderate disease, and 83 (29.9%) had severe disease preoperatively. One-year follow-up data were available for 222 (85.4%) of 260 patients. There was a significant improvement from baseline to one year postoperatively (p < 0.05) in the mJOA score, Nurick grade, NDI score, and all SF-36v2 health dimensions (including the mental and physical health composite scores) except general health. With the exception of the change in the mJOA, the degree of improvement did not depend on the severity of the preoperative symptoms. These results remained unchanged after adjusting for relevant confounders in the multivariate analysis. Fifty-two patients experienced complications (prevalence, 18.7%), with no significant differences among the severity groups. CONCLUSIONS Surgical decompression for the treatment of cervical spondylotic myelopathy was associated with improvement in functional, disability-related, and quality-of-life outcomes at one year of follow-up for all disease severity categories. Furthermore, complication rates observed in the study were commensurate with those in previously reported cervical spondylotic myelopathy series.

Anterior versus posterior surgical approaches to treat cervical spondylotic myelopathy: Outcomes of the prospective multicenter AOSpine north America CSM study in 264 patients

Study Design. A prospective observational multicenter study. Objective. To help solve the debate regarding whether the anterior or posterior surgical approach is optimal for patients with cervical spondylotic myelopathy (CSM). Summary of Background Data. The optimal surgical approach to treat CSM remains debated with varying opinions favoring anterior versus posterior surgical approaches. We present an analysis of a prospective observational multicenter study examining outcomes of surgical treatment for CSM. Methods. A total of 278 subjects from 12 sites in North America received anterior/posterior or combined surgery at the discretion of the surgeon. This study focused on subjects who had either anterior or posterior surgery (n = 264, follow-up rate, 87%). Outcome measures included the modified Japanese Orthopedic Assessment scale, the Nurick scale, the Neck Disability Index, and the Short-Form 36 (SF-36) Health Survey version 2 Physical and Mental Component Scores. Results. One hundred and sixty-nine patients were treated anteriorly and 95 underwent posterior surgery. Anterior surgical cases were younger and had less severe myelopathy as assessed by mJOA and Nurick scores. There were no baseline differences in Neck Disability Index or SF-36 between the anterior and posterior cases. Improvement in the mJOA was significantly lower in the anterior group than posterior group (2.47 vs. 3.62, respectively, P < 0.01), although the groups started at different levels of baseline impairment. The extent of improvement in the Nurick Scale, Neck Disability Index, SF-36 version 2 Physical Component Score, and SF-36 version 2 Mental Component Score did not differ between the groups. Conclusion. Patients with CSM show significant improvements in several health-related outcome measures with either anterior or posterior surgery. Importantly, patients treated with anterior techniques were younger, with less severe impairment and more focal pathology. We demonstrate for the first time that, when patient and disease factors are controlled for, anterior and posterior surgical techniques have equivalent efficacy in the treatment of CSM. Level of Evidence: 3

The expression of anabolic cytokines in intervertebral discs in age-related degeneration.

Study Design. Quantitative analysis of endogenous messenger ribonucleic acid (mRNA) expression of anabolic cytokines in the anulus fibrosus and nucleus pulposus tissue from the intervertebral discs of young and old rabbits was performed. Objectives. To measure the expression of anabolic cytokines bone morphogenetic protein-2 (BMP-2), BMP-7, transforming growth factor-β (TGF-β), and insulin-like growth factor-I (IGF-I) in the anulus fibrosus and nucleus pulposus tissue from young and old rabbits to determine if there are differences with age. Summary of Background Data. Disc degeneration increases with age and is associated with compromised disc chondrocytic function. Molecules such as BMP-2, BMP-7, TGF-β, and IGF-I are known to up-regulate disc cell synthesis of key chondrocytic matrix molecules in vitro, and have been proposed as therapeutic agents to prevent disc degeneration. Previous studies have shown that exogenous anabolic cytokines can up-regulate disc-cell function both in vitro and in vivo, however, the endogenous expression of anabolic cytokines in the disc is still unknown. Methods. New Zealand white rabbits aged 3 years (old) and 6 months (young) were used. Quantitative real-time polymerase chain reaction was performed to measure the mRNA levels of BMP-2, BMP-7, TGF-β1, and IGF-I from anulus fibrosus and nucleus pulposus tissue from young and old rabbits. The discs form the young rabbits represent nondegenerated discs, and the discs from the old rabbits represent discs at the onset of degeneration. Results. In the nucleus pulposus, the mRNA levels, given as a ratio of old to young, were 3.6 for BMP-2 (P = 0.004), 61 for BMP-7 (P = 0.02), 4.0 for TGF-β1 (P = 0.3), and 0.6 for IGF-I (P = 0.2). In the anulus fibrosus, the mRNA levels, given as a ratio of old to young, were 1.6 for BMP-2 (P = 0.07), 4.6 for BMP-7 (P = 0.004), 2.9 for TGF- β1 (P = 0.01), and 2.0 for IGF-I (P = 0.1). Conclusion. The disc tissue from the old rabbits as compared to the young rabbits showed, in general, significantly higher mRNA levels of endogenous BMP-2, BMP-7, and TGF-β in both the anulus fibrosus and nucleus pulposus. The similar patterns of up-regulation in gene expression with age shown by these 3 anabolic cytokines suggest a common pathway in terms of regulation and transcription in the early stage of disc degeneration. The knowledge of the age-related pattern in endogenous gene expression of these anabolic cytokines could provide important information for clinical interventional therapy.

Outcomes after laminoplasty compared with laminectomy and fusion in patients with cervical myelopathy: a systematic review.

Study Design. Systematic review. Objective. To determine the effectiveness and safety of cervical laminoplasty versus laminectomy and fusion for the treatment of cervical myelopathy, and to identify any patient subgroups for whom one treatment may result in better outcomes than the other. Summary of Background Data. Cervical laminoplasty and cervical laminectomy plus fusion are both procedures that treat cervical stenosis induced myelopathy by expanding the space available for the spinal cord. Although there are strong proponents of each procedure, the effectiveness, safety, and differential effectiveness and safety of laminoplasty versus laminectomy and fusion remains unclear. Methods. A systematic search of multiple major medical reference databases was conducted to identify studies that compared laminoplasty with laminectomy and fusion. Studies could include either or both cervical myelopathic spondylosis (CSM) and ossification of the posterior longitudinal ligament. Randomized controlled trials and cohort studies were included. Case reports and studies with less than 10 patients in the comparative group were excluded. Japanese Orthopaedic Association, modified Japanese Orthopaedic Association, and Nurick scores were the primary outcomes measuring myelopathy effectiveness. Reoperation and complication rates were evaluated for safety. Clinical recommendations were made through a modified Delphi approach by applying the Grading of Recommendations Assessment, Development and Evaluation/Agency for Healthcare Research and Quality criteria. Results. The search strategy yielded 305 citations, and 4 retrospective cohort studies ultimately met our inclusion criteria. For patients with CSM, data from 3 class of evidence III retrospective cohort studies suggest that there is no difference between treatment groups in severity of myelopathy or pain: 2 studies reported no significant difference between treatment groups in severity of myelopathy, and 3 studies found no significant difference in pain outcomes between treatment groups. For patients with ossification of the posterior longitudinal ligament, one small class of evidence III retrospective cohort study reported significant improvements in myelopathy severity after laminectomy and fusion compared with laminoplasty, but no differences in long-term pain between treatment groups. The overall evidence on the comparative safety of laminoplasty compared with laminectomy and fusion is inconsistent. Reoperation rates were lower after laminoplasty in 2 of 3 studies reporting. However, the incidence of debilitating neck pain was higher after laminoplasty as reported by one study; results on neurological complications were inconclusive, with 2 studies reporting. Results on kyphotic deformity were inconsistent, with opposite results in the 2 studies reporting. After laminectomy and fusion, 1% to 38% of patients had pseudarthrosis. Infection rates were slightly lower after laminoplasty, but the results are not likely to be statistically significant. Conclusion. For patients with CSM, there is low-quality evidence that suggests that laminoplasty and laminectomy and fusion procedures are similarly effective in treating CSM. For patients with ossification of the posterior longitudinal ligament, the evidence regarding the effectiveness of these procedures is insufficient. For both patient populations, the evidence as to whether one procedure is safer than the other is insufficient. Higher-quality research is necessary to more clearly delineate when one procedure is preferred compared with the other. Evidence-Based Clinical Recommendations. Recommendation. For CSM, evidence suggests that laminoplasty and laminectomy-fusion procedures can be similarly effective. We suggest that surgeons consider each case individually and take into account their own familiarity and expertise with each procedure. Overall Strength of Evidence. Low Strength of Recommendation. Weak

Spine fusion by gene therapy

Over 250 000 patients each year undergo a spine fusion procedure in the US. This constitutes 50% of all bone graft procedures. Despite best efforts, a large percentage of spine fusions (up to 35%) fail to form a solid bony arthrodesis. This is a significant clinical problem and has led to research in bone formation biology to augment spine fusion rates. Both recombinant and purified osteoinductive cytokines have been studied in pilot and pivotal studies in humans. At this point, recombinant human bone morphogenetic protein-2 has received FDA approved for lumbar interbody application with titanium cages. Despite these successes, limitations of directly applying osteoinductive proteins related to cost and carriers remain to be overcome. Gene therapy for spine fusion and other bone healing applications are being pursued as an alternative strategy. This article will review the state of the art of local gene therapy for bone formation and to highlight specific issues, which must be addressed when pursuing such a program. A critical step in using gene therapy for bone formation is choosing an appropriate osteoinductive gene. In choosing the gene, one must consider the differences in efficacy of the gene as well as the gene availability due to proprietary constraints. The choice of delivery vector is important. Factors such as the potency of the gene and the specific application intended play a role in this decision. Next, the effective dose, transduction time, and gene transfer method must be established. The choice of carrier material to form the scaffold for the new bone formation is another critical step that must be optimized for successful bone formation. Finally, a strategy for in vitro and in vivo testing must be developed to maximize the chances of success in human trials.

Predictive factors affecting outcome after cervical laminoplasty.

Study Design. Systematic review. Objective. To determine whether various preoperative factors affect patient outcome after cervical laminoplasty for cervical spondylotic myelopathy (CSM) and/or ossification of posterior longitudinal ligament (OPLL). Summary of Background Data. Cervical laminoplasty is a procedure designed to decompress the spinal cord by enlarging the spinal canal while preserving the lamina. Prior research has identified a variety of potential predictive factors that might affect outcomes after this procedure. Methods. A systematic search of multiple major medical reference databases was conducted to identify studies explicitly designed to evaluate the effect of preoperative factors on patient outcome after cervical laminoplasty for CSM or OPLL. Studies specifically designed to evaluate potential predictive factors and their associations with outcome were included. Only cohort studies that used multivariate analysis, enrolled at least 20 patients, and adjusted for age as a potential confounding variable were included. JOA (Japanese Orthopaedic Association), modified JOA, and JOACMEQ-L (JOA Cervical Myelopathy Evaluation Questionnaire lower extremity function section) scores were the main outcome measures. Clinical recommendations and consensus statements were made through a modified Delphi approach by applying the GRADE (Grading of Recommendation Assessment, Development and Evaluation)/AHRQ (Agency for Healthcare Research and Quality) criteria. Results. The search strategy yielded 433 citations, of which 1 prospective and 11 retrospective cohort studies met our inclusion criteria. Overall, the strength of evidence from the 12 studies is low or insufficient for most of the predictive factors. Increased age was not associated with poorer JOA outcomes for patients with CSM, but there is insufficient evidence to make a conclusion for patients with OPLL. Increased severity of disease and a longer duration of symptoms might be associated with JOA outcomes for patients with CSM. Hill-shaped lesions might be associated with poorer JOA outcomes for patients with OPLL. There is insufficient evidence to permit conclusions regarding other predictive factors. Conclusion. Overall, the strength of evidence for all of the predictive factors was insufficient or low. Given that cervical myelopathy due to CSM tends to be progressive and that increased severity of myelopathy and duration of symptoms might be associated with poorer outcomes after cervical laminoplasty for CSM, it is preferable to perform laminoplasty in patients with CSM earlier rather than waiting for symptoms to get worse. Further research is needed to more clearly identify predictive factors that affect outcomes after cervical laminoplasty because there were relatively few studies identified that used multivariate analyses to control for confounding factors and many of these studies did not provide a detailed description of the multivariate analyses or the magnitude of effect estimates. Evidence-Based Clinical Recommendations. Recommendation 1. For patients with CSM, increased age is not a strong predictor of clinical neurological outcomes after laminoplasty; therefore, age by itself should not preclude cervical laminoplasty for CSM. Overall Strength of Evidence. Low Strength of Recommendation. Strong Recommendation 2. For patients with CSM, increased severity of disease and a longer duration of symptoms might be associated with poorer clinical neurological outcomes after laminoplasty; therefore, we recommend that patients be informed about this. Overall Strength of Evidence. Low Strength of Recommendation. Strong Summary Statements. For patients with OPLL, hill-shaped lesions might be associated with poorer clinical neurological outcomes after laminoplasty; therefore, surgeons might consider potential benefits and risks of alternative or additional surgery.

Do the Adjacent Level Intervertebral Discs Degenerate After a Lumbar Spinal Fusion? An Experimental Study Using a Rabbit Model

Study Design. A rabbit model of disc degeneration adjacent to a lumbar spinal fusion. Objective. To use a rabbit model to determine the long-term changes in the intervertebral discs at the levels above (cephalad) and below (caudad) 2 fused lumbar levels. Summary of Background Data. Lumbar spinal fusion is generally carried out to eliminate motion at a specific lumbar level. However, it is commonly thought that by eliminating motion at a level, one increases the motion at the adjacent levels cephalad and caudad the fused levels. There have been studies that have reported on degeneration occurring at the cephalad and caudad levels adjacent to the fused levels. Methods. A total of 9 New Zealand white, female rabbits: 4 rabbits in the control group and 5 rabbits in the experimental group. The 5 rabbits in the experimental group underwent a posterolateral 2-level lumbar spinal fusion from L3 to L5. The changes in the lumbar discs were assessed using radiographs, magnetic resonance (MR) images, and histology at 6 months and 12 months. Results. The results at 6 months are less clear than those at 12 months. The results at 12 months for the experimental group are (1) the intervertebral disc height decreased at the caudad adjacent level and to a lesser extent at the cephalad adjacent level; (2) the MRI scores for the discs at the caudad and cephalad adjacent levels showed severe loss of signal intensity as compared to the discs at the same levels in the control group. This loss was more pronounced at the caudad level where the loss of signal intensity was similar to that seen at the fused levels; (3) the histologic analysis showed severe degenerative changes with a lack of live cells in the nucleus pulposus and in the endplate at the caudad adjacent level. At the cephalad level, live cells were apparent (albeit few) in the nucleus pulposus, and there was a more normal looking endplate with live cells. Conclusion. The intervertebral discs at both the cephalad and the caudad levels adjacent to the 2 fused lumbar levels in this rabbit-model experiment carried out over 12 months after surgery showed degenerative changes asassessed using disc-height measurements, MR images, and histology, and the effect was more severe at the caudad adjacent level.

Mild diabetes is not a contraindication for surgical decompression in cervical spondylotic myelopathy: results of the AOSpine North America multicenter prospective study (CSM)

BACKGROUND CONTEXT Cervical spondylotic myelopathy (CSM) is a chronic spinal cord disease and can lead to progressive or stepwise neurologic decline. Several factors may influence this process, including extent of spinal cord compression, duration of symptoms, and medical comorbidities. Diabetes is a systemic disease that can impact multiple organ systems, including the central and peripheral nervous systems. There has been little information regarding the effect of diabetes on patients with coexistent CSM. PURPOSE To provide empirical data regarding the effect of diabetes on treatment outcomes in patients who underwent surgical decompression for coexistent CSM. STUDY DESIGN/SETTING Large prospective multicenter cohort study of patients with and without diabetes who underwent decompressive surgery for CSM. PATIENT SAMPLE Two hundred thirty-six patients without and 42 patients with diabetes were enrolled. Of these, 37 were mild cases and five were moderate cases. Four required insulin. There were no severe cases associated with end-organ damage. OUTCOME MEASURES Self-report measures include Neck Disability Index and version 2 of 36-Item Short Form Health Survey (SF-36v2), and functional measures include modified Japanese Orthopedic Association (mJOA) score and Nurick grade. METHODS We compared presurgery symptoms and treatment outcomes between patients with and without diabetes using univariate and multivariate models, adjusting for demographics and comorbidities. RESULTS Diabetic patients were older, less likely to smoke, and more likely to be on social security disability insurance. Patients with diabetes presented with a worse Nurick grade, but there were no differences in mJOA and SF-36v2 at presentation. Overall, there was a significant improvement in all outcome parameters at 12 and 24 months. There was no difference in the level of improvement between the patients with and without diabetes, except in the SF-36v2 Physical Functioning, in which diabetic patients experienced significantly less improvement. There were no differences in surgical complication rates between diabetic patients and nondiabetic patients. CONCLUSIONS Except for a worse Nurick grade, diabetes does not seem to affect severity of symptoms at presentation for surgery. More importantly, with the exception of the SF-36v2 Physical Functioning scores, outcomes of surgical treatment are similar in patients with diabetes and without diabetes. Surgical decompression is effective and should be offered to patients with diabetes who have symptomatic CSM and are appropriate surgical candidates.

The AdLMP-1 transfection in two different cells; AF cells, chondrocytes as potential cell therapy candidates for disc degeneration

SummaryBackground. LMP-1 is known to increase proteoglycan production through the upregulating the BMPs and it is also known that BMP-2 acts on anulus fibrosus cells and chondrocytes to increase proteoglycan production. Method. We carried out an experiment, the effect of AdLMP-1 transfection on AF cells and chondrocytes in the production of sulfated-glycosaminoglycans, mRNA expression (aggrecan, type I, II collagen, LMP-1, BMP-2, and BMP-7), and immunofluorescence staining.AF cells and chondrocytes were grown in monolayer and treated for 6 days with AdLMP1-green fluorescence protein (GFP) (10, 20, and 30 multiplicity of infection [MOI]). After 6 days, the sGAG content in the media was quantified using 1,9-dimethylmethylene blue staining. The mRNA expression was measured with real-time PCR after 20 MOI infection of AdLMP1-GFP. The each cells treated with 20 MOI infection of AdGFP was used as a control group for the mRNA expression.The each cell group was immunofluorescence stained with each antibodies in the chamber slide at 3 × 104 cells/chamber. Findings. 1) The sGAG production was maximum in 20 MOI AdLMP1-GFP infection on the AdLMP-1 treatment for both of AF cells and chondrocytes. 2) The mRNA expression of aggrecan, type I collagen, type II collagen, LMP-1, BMP-2, and BMP-7 is increased in both AF cells and chondrocytes in 20 MOI AdLMP1-GFP infection. 3) On the immunofluorescence staining results, the positive immunofluorescence stained cell numbers are increased after 20 MOI AdLMP1-GFP infection concordant with upregulation of mRNA expression. Conclusions. The AdLMP-1 treatments in AF cells and chondrocytes may be useful for cell transplantation therapy in disc degeneration.