Alterations in DNA methylation machinery in a rat model of osteoarthritis of the hip.

BACKGROUND: This study aimed to validate alterations in the gene expression of DNA methylation-related enzymes and global methylation in the peripheral blood mononuclear cell (PBMC) and synovial tissues of animal hip osteoarthritis (OA) models. METHODS: Animals were assigned to the control (no treatment), sham (25 µL of sterile saline), and OA (25 µL of sterile saline and 2 mg of monoiodoacetate) groups. Microcomputed tomography scan, histopathological assessment and pain threshold measurement were performed after induction. The mRNA expression of the DNA methylation machinery genes and global DNA methylation in the PBMC and hip synovial tissue were evaluated. RESULTS: The OA group presented with hip joint OA histopathologically and radiologically and decreased pain threshold. The mRNA expression of DNA methyltransferase (Dnmt 3a), ten-eleven translocation (Tet) 1 and Tet 3 in the synovial tissue of the OA group was significantly upregulated. Global DNA methylation in the synovial tissue of the OA group was significantly higher than that of the control and sham groups. CONCLUSIONS: The intra-articular administration of monoiodoacetate induced hip joint OA and decreased pain threshold. The DNA methylation machinery in the synovial tissues of hip OA was altered.

Bone union-promoting effect of romosozumab in an ovariectomized rat posterolateral lumbar fusion model.

Spinal fixation surgery has been increasingly performed in patients with osteoporosis. Romosozumab, a drug that was introduced in Japan recently, is known to possibly promote bone healing. However, few studies have reported the therapeutic effects of romosozumab in clinical practice in Japan. Therefore, here, we investigated the effects of romosozumab dosage on bone fusion promotion using an ovariectomized rat spinal fusion model. Eight-week-old female Sprague-Dawley rats were matched by body weight and divided into three groups: 1.0 romosozumab (R) group (Evenity®, 25 mg/kg), 1/10R group (Evenity®, 2.5 mg/kg), and control (C) group (saline). Subcutaneous injections were administered twice a week for 8 weeks postoperatively. Computed tomography scans were performed every 2 weeks from the time of surgery till 8 weeks postoperatively. The mean fusion rates in terms of volume were significantly higher in the R groups [1/10R, 1.0R] than in the C group from 4 weeks postoperatively. The rate of increase was significantly higher in the 1.0R group from 4 weeks postoperatively and in the 1/10R group from 6 weeks postoperatively, than in the C group. The proportion of trabecular bone area was approximately 1.5 times higher in the R groups than in the C group. No significant differences were observed between the R groups. Our results suggest that romosozumab stimulates bone growth at the graft site, and similar effects were achieved at 1/10 of the standard dosage.

Short-Term Clinical and Radiographic Evaluation of Patients Treated With Expandable and Static Interbody Spacers Following Lumbar Lateral Interbody Fusion.

OBJECTIVE: The goal of this study was to evaluate, using computed tomography (CT) and magnetic resonance imaging (MRI), patients who underwent oblique lateral interbody fusion (OLIF) using either expandable or static interbody spacers. METHODS: Thirty-five patients with degenerative disc disease were surgically treated with one-level OLIF and were followed up for more than 6 months. The Static group consisted of 22 patients, and 13 patients were in the Expandable group. Intraoperative findings included operative time (min), blood loss (ml), and cage size. Low back pain, leg pain, and leg numbness were measured using the Japanese Orthopedic Association score, visual analogue score, and the Roland-Morris Disability Questionnaire. Radiologic evaluation using computed tomography (CT) and magnetic resonance imaging (MRI) allowed measurement of cage subsidence, cross-sectional area (CSA) of the dural sac, disc height, segmental lordosis, foraminal height, and foraminal CSA preoperatively and 6 months postoperatively. RESULTS: The Expandable group had significantly larger cage height and lordosis than the Static group (P < 0.05). The Expandable group also had greater dural sac area expansion and enlargement of the intervertebral foramen, as well as better correction of vertebral body slip (P < 0.05). Cage subsidence was significantly lower in the Expandable group (P < 0.05). JOA and VAS scores for leg numbness were significantly better in the Expandable group (P < 0.05). CONCLUSIONS: Compared with static spacers, expandable spacers significantly enlarged the dural sac area, corrected vertebral body slippage, expanded the intervertebral foramen, and achieved good indirect decompression while reducing cage subsidence, resulting in improvement in clinical symptoms.

Quantitative evaluation of the lumbar ligamentum flavum using MRI T2-mapping: Efficacy of its clinical application in patients with lumbar spinal stenosis.

OBEJECTIVE: To perform a magnetic resonance imaging T2-mapping of the ligamentum flavum in healthy individuals and patients with lumbar spinal stenosis scheduled for surgery and compare the T2 relaxation times. SUBJECTS AND METHODS: The T2 relaxation time of the ligamentum flavum was compared among 3 groups, healthy young individuals (H group (age< 50)), healthy middle-aged and older individuals (H group (age≥50)), and patients with lumbar spinal stenosis (L group). Additionally, the thickness of the ligament was measured in the axial image plane, and the occupied area ratio of each fiber was measured by staining the surgically obtained ligament, and each was correlated with the T2 relaxation time. We also evaluated the adhesion of the ligamentum flavum with the dura mater during the surgery. RESULTS: The T2 relaxation times were significantly prolonged in H group (age ≥50) and L group (P < 0.001) compared to H group (age<50). The relationship between collagen fiber and T2 relaxation times was significantly positive (r = 0.720, P < 0.001). Moreover, the relaxation times were significantly prolonged in those with adhesion of the ligamentum flavum with the dura mater (P < 0.05). The cut-off for the relaxation time was 50 ms (sensitivity: 62.50%, false positive rate: 10.8%). CONCLUSION: Healthy middle-aged and older individuals and patients with lumbar spinal stenosis and adhesion of the ligamentum flavum with the dura mater have prolonged T2 relaxation times. Hence, the adhesion between the ligamentum flavum and dura mater should be considered in cases with a relaxation time ≥50 ms.

Objective Assessment of Sleep Disorders in Patients with Lumbar Spinal Stenosis Using Wearable Trackers.

Introduction: Low-back pain causes sleep disorders, which impairs the quality of life (QOL) of patients. Sleep disorders are associated with lumbar spinal stenosis (LSS); however, the postoperative effects of LSS surgery on sleep disorders are unknown. This study aimed to assess sleep disorders in patients with LSS using wearable activity trackers and determine whether surgery improves sleep quality. Methods: A total of 39 patients scheduled for LSS surgery (mean age 71.1±8.7 years; 22 men and 17 women) were studied. Sleep disorders in the participants were objectively evaluated using a wearable Motionlogger Micro system. Sleep efficiency (SEf), mean active count (MAC), and wake after sleep onset (WASO) were measured before and 6 months following surgery. Furthermore, the patient-based outcomes of pain and QOL-related scores were measured and compared with those of healthy participants. The group with improved SEf following surgery was designated as "nonpoor sleepers," whereas the group that did not exhibit improvements was designated as "poor sleepers." The two groups were compared based on patient factors, patient-based questionnaires, and sleep disorder measurements. Results: The SEf and WASO were significantly worse in patients with LSS compared with healthy participants (P<0.05). Furthermore, the SEf in patients with LSS was associated with the Oswestry Disability Index scores. No improvement was observed in the SEf, MAC, and WASO before and after surgery. Evaluation of each case revealed 21 and 12 cases of nonpoor and poor sleepers, respectively. Preoperative low-back pain was significantly associated with improvement in postoperative sleep quality. Conclusions: Sleep disorders in patients with LSS were evaluated, and improvement in sleep disorders following surgery was associated with the intensity of preoperative low-back pain. Sleep disorders are associated with QOL disorders, suggesting that focusing on the treatment of sleep disorders is important in the management of patients with LSS.

Efficacy of radial shock wave therapy on rat models of adjuvant arthritis.

BACKGROUND: Extracorporeal shock wave therapy (ESWT) is an effective treatment for musculoskeletal pain, tendinopathy, and fasciitis with an anti-inflammatory effect. ESWT can be categorized into two groups: radial pressure wave (RPW) and focused shock wave (FSW). Although there have been several studies on the inflammation and pain-improvement mechanisms of FSW, there are few studies on the pain-improvement mechanisms of RPW. This study aimed to elucidate the efficacy of RPW in a rat model of adjuvant arthritis. METHODS: Ninety-six rats were randomly categorized into three groups: RPW, control, and sham as follows: (I) RPW group, which received RPW application after complete Freund's adjuvant (CFA) injection; (II) Control group, which received only CFA injection; and (III) Sham group, which received only saline injection. All rats were evaluated at 0, 4, 7, 14, 28, and 56 days post-RPW application based on foot circumference, von Frey test, and immunohistochemistry of nerve fibers for calcitonin gene-related peptide (CGRP) and protein gene product (PGP) 9.5 in plantar skins. RESULTS: There were no significant differences in foot circumference between the RPW and control groups at any time point. The RPW group showed significant improvements in the von Frey test results on days 7 and 14. The total CGRP-immunoreactive (ir) and PGP9.5-ir nerve fiber lengths in the RPW group decreased on day 0; however, both were increased in the control group. The CGRP-ir and PGP9.5-ir nerve fibers in the RPW group were significantly shorter than those in the control group until day 14 after RPW. CONCLUSIONS: RPW improved the mechanical hypersensitivity between days 7 and 14 after application. Like FSW, RPW also induced the degeneration of sensory nerve fibers in the skin in the early period after irradiation, and reinnervation occurred between 14 and 28 days. Thus, our results demonstrate one of the pain relief mechanisms after RPW application.

Combined effect of DBM, PRP, and bone marrow fluid on bone union in a rat posterolateral fusion model.

Platelet-rich plasma (PRP) promotes bone union through osteoinduction. We investigated whether adding demineralized bone matrix (DBM), derived naturally from biomaterial and with various growth factors, for osteoconductivity and bone marrow fluid for osteogenesis results in different bone unions. Eight-week-old male Sprague-Dawley rats were divided into four groups of five based on transplantation material: sham control (C group); DBM alone (D group); DBM + PRP (DP group); and DBM + PRP + bone marrow fluid (DPB group). After posterolateral fusion at L3-5, postoperative weekly CT imaging determined average number of bone union in facet joints (4 joints × 5 animals = 20 joints) and bone formation. Pathological evaluation and bone strength were assessed using 3-point bending two weeks postoperatively. Facet joint bone union at four weeks postoperatively was 4/20 (20%, DP group) and 8/20 (40%, DPB group) joints. Six weeks postoperatively, it was 7/20 (35%, D group), 12/20 (60%, DP group), and 16/20 (80%, DPB group). Eight weeks postoperatively, it was 13/20 (65%, D group), 17/20 (85%, DP group), and 20/20 (100%, DPB group), suggesting that DPB > DP > D > C. Bone formation and bone strength showed a similar DPB > DP > D > C group trend. Adding PRP and bone marrow fluid to DBM promotes bone union and strength.

Analgesic effects and arthritic changes following intra-articular injection of diclofenac etalhyaluronate in a rat knee osteoarthritis model.

BACKGROUND: Diclofenac etalhyaluronate (DF-HA) is a recently developed analgesic conjugate of diclofenac and hyaluronic acid that has analgesic and anti-inflammatory effects on acute arthritis. In this study, we investigated its analgesic effect on osteoarthritis, using a rat model of monoiodoacetate (MIA). METHODS: We injected MIA into the right knees of eight 6-weeks-old male Sprague-Dawley rats. Four weeks later, rats were randomly injected with DF-HA or vehicle into the right knee. Seven weeks after the MIA injection, fluorogold (FG) and sterile saline were injected into the right knees of all the rats. We assessed hyperalgesia with weekly von Frey tests for 8 weeks after MIA administration. We took the right knee computed tomography (CT) as radiographical evaluation every 2 weeks. All rats were sacrificed 8 weeks after administration of MIA for histological evaluation of the right knee and immunohistochemical evaluation of the DRG and spinal cord. We also evaluated the number of FG-labeled calcitonin gene-related peptide (CGRP)-immunoreactive(ir) neurons in the dorsal root ganglion (DRG) and ionized calcium-binding adapter molecule 1 (Iba1)-ir microglia in the spinal cord. RESULTS: Administration of DF-HA significantly improved pain sensitivity and reduced CGRP and Iba1 expression in the DRG and spinal cord, respectively. However, computed tomography and histological evaluation of the right knee showed similar levels of joint deformity, despite DF-HA administration. CONCLUSION: DF-HA exerted analgesic effects on osteoarthritic pain, but did not affect joint deformity.

Updates on cadaver surgical training in Japan: a systematic facility at Chiba University.

Cadaver surgical training (CST), which ensures medical safety by improving the skills of surgeons, is popular overseas. However, training involves ethical issues given the use of cadavers. In 2012, the Japan Surgical Society and the Japanese Association of Anatomists compiled and opened the "Guidelines for Cadaver Dissection in Education and Research of Clinical Medicine (Guideline 2012)" to the public. This has allowed Japan to conduct CST or research under the regulations of Postmortem Examination and Corpse Preservation Act and the Body Donation Act. However, its dissemination has been sluggish. The Clinical Anatomy Lab (CAL), established in 2010 at Chiba University, is a facility for conducting CST and research. In the 11 years since its inception, 250 programs have been implemented. Orthopedics had the most implemented in the clinical field, with 120 (48%), followed by emergency and critical care medicine with 27 (10.8%), and neurological surgery with 27 (10. 8%). Based on the purpose of the training, the most common objective for the programs (approximately 83%) was education. Further, the highest number of programs was recorded in 2018 (34) and participants in 2017 (631). The implementation of CST requires more than just guiding surgeons to a dissection practice room. There are several methods of preserving cadavers to make them suitable for CST. For various surgical simulations, an operating table is more suitable than a dissection table. The current paper provides information on how to implement CST in universities that have so far only worked on anatomy education for medical students.

Bone union-promoting effect of romosozumab in a rat posterolateral lumbar fusion model.

This study investigated the effect of romosozumab on bone union in a rat posterolateral lumbar fixation model. Posterolateral lumbar fixation was performed on 8-week-old male Sprague Dawley rats (n = 20). For bone grafting, autogenous bone (40 mg) was harvested from the spinous processes of the 10th thoracic vertebra until the 2nd lumbar vertebra and implanted between the intervertebral joints and transverse processes of the 4th and 5th lumbar vertebrae on both sides. Rats were matched by body weight and equally divided into two groups: R group (Evenity®, 25 mg/kg) and control (C) group (saline). Subcutaneous injections were administered twice a week until 8 weeks after surgery. Computed tomography was performed at surgery and week 8 after surgery. The area and percentage of bone trabeculae in the total area of bone fusion were calculated. Statistical analysis was performed using an unpaired t test (p < 0.05). We found that the R group rats had significantly higher mean bone union rate and volume than did the C group rats at all time courses starting week 4 after surgery. The R group had significantly higher increase rates than did the C group at weeks 4 and 6 after surgery. The percentage of bone trabeculae area in the R group was approximately 1.7 times larger than that in the C group. Thus, we demonstrated that romosozumab administration has stimulatory effects on bony outgrowth at bone graft sites. We attribute this to the modeling effect of romosozumab.

Usefulness of Simultaneous Magnetic Resonance Neurography and Apparent T2 Mapping for the Diagnosis of Cervical Radiculopathy.

STUDY DESIGN: Retrospective observational study. PURPOSE: We investigated the correlation between T2 relaxation times and clinical symptoms in patients with cervical radiculopathy caused by cervical disk herniation. OVERVIEW OF LITERATURE: There are currently no imaging modalities that can assess the affected cervical nerve roots quantitatively. METHODS: A total of 14 patients with unilateral radicular symptoms and five healthy subjects were subjected to simultaneous apparent T2 mapping and neurography with nerve-sheath signal increased with inked rest-tissue rapid acquisition of relaxation enhancement signaling (SHINKEI-Quant) using a 3-Tesla magnetic resonance imaging. The Visual Analog Scale (VAS) score for neck pain and upper arm pain was used to evaluate clinical symptoms. T2 relaxation times of the cervical dorsal root ganglia of the brachial plexus were measured bilaterally from C4 to C8 in patients with radicular symptoms and from C5 to C8 in healthy controls. The T2 ratio was calculated as the affected side to unaffected side. RESULTS: When comparing nerve roots bilaterally at each spinal level, no significant differences in T2 relaxation times were found between patients and healthy subjects. However, T2 relaxation times of nerve roots in the patients with unilateral radicular symptoms were significantly prolonged on the involved side compared with the uninvolved side (p<0.05). The VAS score for upper arm pain was not significantly correlated with the T2 relaxation times, but was positively correlated with the T2 ratio. CONCLUSIONS: In patients with cervical radiculopathy, the SHINKEI-Quant technique can be used to quantitatively evaluate the compressed cervical nerve roots. The VAS score for upper arm pain was positively correlated with the T2 ratio. This suggests that the SHINKEI-Quant is a potential tool for the diagnosis of cervical nerve entrapment.

Improvements in Intractable Lumbar and LowerExtremity Symptoms after Systemic Administration of Tocilizumab, an Anti-interleukin-6 Receptor Antibody.

STUDY DESIGN: Prospective cohort study (open-label, single-arm, and non-blinded). PURPOSE: This study aims to determine the effects of systemic administration of tocilizumab, an anti-interleukin-6 (IL-6) receptor antibody on refractory low back pain and leg symptoms. OVERVIEW OF LITERATURE: IL-6 overexpression is associated with neuropathic pain pathogenesis, which is potentially followed by chronic low back pain, including leg pain and numbness. This finding suggest that inhibition of IL-6 at the site of pain or in the transmission pathway could provide novel therapeutic targets for chronic low back pain. METHODS: This prospective, single-arm study included 11 patients (eight men; mean age, 62.7 years) with ≥3-months' chronic pain history due to lumbar disease. Subcutaneous TCZ injections were administered twice, at a 2-week interval. We evaluated low back pain, leg pain, and leg numbness using numeric rating scales and the Oswestry Disability Index (ODI; baseline and 6 months postinjection); serum IL-6 and tumor necrosis factor-α levels (baseline and 1 month postinjection); and clinical adverse events. RESULTS: Intractable symptoms reduced after TCZ administration. Low back pain improved for 6 months. Improvements in leg pain and numbness peaked at 4 and 1 month, respectively. Improvements in ODI were significant at 1 month and peaked at 4 months. Serum IL-6 was increased at 1 month. IL-6 responders (i.e., patients with IL-6 increases >10 pg/mL) showed particularly significant improvements in leg pain at 2 weeks, 1 month, and 2 months compared with nonresponders. We observed no apparent adverse events. CONCLUSIONS: Systemic TCZ administration improved symptoms effectively for 6 months, with peak improvements at 1-4 months and no adverse events. Changing serum IL-6 levels correlated with leg pain improvements; further studies are warranted to elucidate the mechanistic connections between lumbar disorders and inflammatory cytokines.

Analgesic effects and arthritic changes following tramadol administration in a rat hip osteoarthritis model.

We investigated the analgesic effects of tramadol and the arthritic changes following tramadol administration in the rat hip osteoarthritis (OA) model using mono-iodoacetate (MIA). The right hip joints of male Sprague-Dawley rats (n = 5 rats/group) in the Sham group were injected with 25 µl of sterile saline and 1% of fluorogold (FG) retrograde neurotracer. In the MIA + Vehicle and MIA + Tramadol groups, FG and 25 µl of sterile saline with 0.5 mg of MIA were injected into the right hip joint. The MIA + Vehicle and MIA + Tramadol groups were administered daily for 4 weeks, either sterile saline (10 mg/kg, intraperitoneal [i.p.]) or tramadol (10 mg/kg, i.p.). We assessed hyperalgesia every week after MIA administration. Histopathological changes and immunoreactive neurons for calcitonin gene-related peptide (CGRP) in dorsal root ganglia (DRG) were evaluated after 4 weeks of treatment. MIA injection into the hip joint led to mechanical hyperalgesia (p < 0.01), which was significantly reduced by tramadol administration (p < 0.01). Furthermore, daily i.p injection of tramadol significantly suppressed CGRP expression in DRG (p < 0.0001). MIA + Vehicle and MIA + Tramadol groups showed significant cartilage reduction and degeneration compared to the Sham group (p < 0.0001). Interestingly, OA changes significantly progressed in the MIA + Tramadol group compared to the MIA + Vehicle group (p < 0.0001).

Effect of voluntary running activity on mRNA expression of extracellular matrix genes in a mouse model of intervertebral disc degeneration.

INTRODUCTION: Low back pain (LBP), a leading cause of global disability, is often associated with intervertebral disc degeneration (IDD). Exercise therapy is recommended for chronic LBP management and affects many tissues and organ systems. However, the ability of exercise to repair the extracellular matrix (ECM) in degenerating discs is unclear. The aims of the study were to examine mRNA expression of ECM structural components (collagen I, II, X, aggrecan) and regulators of matrix turnover (matrix metalloproteinases (MMP)-3, - 9, - 13, ADAMTS-4, - 5, TIMP1-4, CCN2) between age-matched (a) wild-type and secreted protein acidic and rich in cysteine (SPARC)-null, (b) sedentary and active, and (c) male and female mice. METHODS: At 8 months of age, male and female SPARC-null and wild-type control mice received a home cage running wheel or a control, fixed wheel for 6 months. Deletion of the SPARC gene results in progressive IDD beginning at 2 to 4 months of age. Increased activity was confirmed, and qPCR was performed on excised lumbar discs. RESULTS: Male SPARC-null mice expressed less aggrecan mRNA than wild-type controls. After 6 months of running, collagen, MMP3, and MMP13 expression was increased in male and MMP3 was increased in female SPARC-null mice. Sex differences were observed in wild-type mice and in response to IDD and long-term running. CONCLUSIONS: Voluntary running results in changes in mRNA consistent with increased ECM turnover and disc regeneration. Improved disc ECM might contribute to the beneficial effects of exercise on LBP and may create an intradiscal environment hospitable to regenerative therapies. Sex-specific differences should be considered in the development of disc-targeting therapies.

Time-Course Changes in Bone Metabolism Markers and Density in Patients with Osteoporosis Treated with Romosozumab: A Multicenter Retrospective Study.

PURPOSE: In this multicenter retrospective observational study, we examined the early effects of romosozumab in patients with severe osteoporosis in terms of time-course changes in bone metabolism marker, improvement in bone density, and adverse effects. MATERIALS AND METHODS: Patients with severe osteoporosis were included. We investigated the progress of TRACP 5b and P1NP before and 1-2 months after the administration of romosozumab. We also investigated the bone density of lumbar spine, femoral neck, and the entire femur, measured by the DXA method, before and 5-7 months after the administration of romosozumab. RESULTS: A total of 70 patients (7 males and 63 females, age 75.0±3.6 years) participated in this study. Significant improvements in TRACP 5b and P1NP levels were observed before and 1-2 months after romosozumab administration. The average bone density of lumbar spine, femoral neck, and the entire femur were measured before and 5-7 months after romosozumab administration; and a significant increase only observed in the lumbar spine. CONCLUSION: Consistent with the findings of previous clinical studies, romosozumab has both bone formation-enhancing and bone resorption effects (dual effect). In addition, romosozumab also demonstrated improvement in bone density from the early phase after the administration, though the result was only seen in the lumbar spine.

Comparison between intervertebral oblique lumbar interbody fusion and transforaminal lumbar interbody fusion: a multicenter study.

This study aimed to perform a comparative analysis of postoperative results between lumbar degenerative spondylolisthesis (LDS) treated with oblique lateral interbody fusion (OLIF) and transforaminal lumbar interbody fusion (TLIF) from the Chiba spine surgery registry database. Sixty-five patients who underwent single-level OLIF (O group) for LDS with ≥ 3 years' follow-up were retrospectively reviewed. The control group comprised 78 patients who underwent single-level TLIF (T group). The analyzed variables included global alignment, radiological parameters of fused segments, asymptomatic and symptomatic ASD incidence, clinical outcomes at 3 years postoperatively using the Japanese Orthopedic Association Back Pain Evaluation Questionnaire data, visual analogue scale scores for low back pain, lower extremity pain, and lower extremity numbness. There was no significant change in global alignment between the two groups. The rate of improvement in anterior intervertebral disc height was not significantly different between the groups at 1-month postoperatively. However, at the final evaluation, the anterior intervertebral disc height and incidence of asymptomatic ASD were significantly higher in the O group. There was no significant difference in symptomatic ASD, reoperation cases, or clinical results between groups. Thus, single-level OLIF can maintain the corrected disc height, but as it has no effect on global alignment, its benefit is limited.

An Injectable Hyaluronic Acid Hydrogel Promotes Intervertebral Disc Repair in a Rabbit Model.

STUDY DESIGN: An in vivo model to study the effect of an injectable hyaluronic acid (HA) hydrogel following puncture-induced lumbar disc injury in rabbits. OBJECTIVES: The aim of this study was to determine the efficacy of an injectable HA hydrogel to maintain disc height and tissue hydration, promote structural repair, and attenuate inflammation and innervation in the lumbar discs. SUMMARY OF BACKGROUND DATA: Previously, we have demonstrated that HA hydrogel alleviated inflammation, innervation, and pain to promote disc repair. Nevertheless, the effect of an injectable HA hydrogel in the lumbar disc in a weight-bearing animal model was not performed. METHODS: We have adopted a surgically puncture-induced disc injury at lumbar levels in a rabbit model. The discs were grouped into sham, puncture with water injection, and puncture with HA hydrogel injection. Postoperatively, we measured changes in disc height using x-ray. We used magnetic resonance imaging to assess disc degeneration on tissue hydration after euthanasia. Post-mortem, we determined histological changes, innervation (PGP9.5) and inflammation (interleukin [IL]-6, IL-1ß, and tumor necrosis factor [TNF]-α) in the discs. RESULTS: We have demonstrated a significant reduction of disc height and T2/T1ρ mapping with histological evidence of degenerative discs, increase of innervation and inflammation in puncture-induced disc injury over time. In the HA hydrogel group, disc height was increased at weeks four and eight. A slight increase of T2 mapping, but significantly in T1ρ mapping, was observed in the HA hydrogel group at week 8. We observed homogenous NP distribution and organised AF lamellae at week eight and a slight reduced innervation score in the treatment group. HA hydrogel significantly downregulated IL-6 expression at day 1. This, however, was only slightly reduced for IL-1ß and TNF-α. CONCLUSION: An injectable HA hydrogel had the protective effects in suppressing the loss of disc height, promoting tissue hydration for structural repair, and attenuating inflammation and innervation to prevent further disc degeneration.Level of Evidence: N/A.

Exercise attenuates low back pain and alters epigenetic regulation in intervertebral discs in a mouse model.

BACKGROUND CONTEXT: Chronic low back pain (LBP) is a multifactorial disorder with complex underlying mechanisms, including associations with intervertebral disc (IVD) degeneration in some individuals. It has been demonstrated that epigenetic processes are involved in the pathology of IVD degeneration. Epigenetics refers to several mechanisms, including DNA methylation, that have the ability to change gene expression without inducing any change in the underlying DNA sequence. DNA methylation can alter the entire state of a tissue for an extended period of time and thus could potentially be harnessed for long-term pain relief. Lifestyle factors, such as physical activity, have a strong influence on epigenetic regulation. Exercise is a commonly prescribed treatment for chronic LBP, and sex-specific epigenetic adaptations in response to endurance exercise have been reported. However, whether exercise interventions that attenuate LBP are associated with epigenetic alterations in degenerating IVDs has not been evaluated. PURPOSE: We hypothesize that the therapeutic efficacy of physical activity is mediated, at least in part, at the epigenetic level. The purpose of this study was to use the SPARC-null mouse model of LBP associated with IVD degeneration to clarify (1) if IVD degeneration is associated with altered expression of epigenetic regulatory genes in the IVDs, (2) if epigenetic regulatory machinery is sensitive to therapeutic environmental intervention, and (3) if there are sex-specific differences in (1) and/or (2). STUDY DESIGN: Eight-month-old male and female SPARC-null and age-matched control (WT) mice (n=108) were assigned to exercise (n=56) or sedentary (n=52) groups. Deletion of SPARC is associated with progressive IVD degeneration and behavioral signs of LBP. The exercise group received a circular plastic home cage running wheel on which they could run freely. The sedentary group received an identical wheel secured in place to prevent rotation. After 6 months, the results obtained in each group were compared. METHODS: After 6 months of exercise, LBP-related behavioral indices were determined, and global DNA methylation (5-methylcytosine) and epigenetic regulatory gene mRNA expression in IVDs were assessed. This project was supported by the Canadian Institutes for Health Research. The authors have no conflicts of interest. RESULTS: Lumbar IVDs from WT sedentary and SPARC-null sedentary mice had similar levels of global DNA methylation (%5-mC) and comparable mRNA expression of epigenetic regulatory genes (Dnmt1,3a,b, Mecp2, Mbd2a,b, Tet1-3) in both sexes. Exercise attenuated LBP-related behaviors, decreased global DNA methylation in both WT (p<.05) and SPARC-null mice (p<.01) and reduced mRNA expression of Mecp2 in SPARC-null mice (p<.05). Sex-specific effects of exercise on expression of mRNA were also observed. CONCLUSIONS: Exercise alleviates LBP in a mouse model. This may be mediated, in part, by changes in the epigenetic regulatory machinery in degenerating IVDs. Epigenetic alterations due to a lifestyle change could have a long-lasting therapeutic impact by changing tissue homeostasis in IVDs. CLINICAL SIGNIFICANCE: This study confirmed the therapeutic benefits of exercise on LBP and suggests that exercise results in sex-specific alterations in epigenetic regulation in IVDs. Elucidating the effects of exercise on epigenetic regulation may enable the discovery of novel gene targets or new strategies to improve the treatment of chronic LBP.

The Effect of Megakaryocytes and Platelets Derived from Human-Induced Pluripotent Stem Cells on Bone Formation.

INTRODUCTION: Platelet-rich plasma (PRP) is drawing attention as a substance that can promote bone formation. The growth factors present in PRP are stable for a long time after freeze-drying. However, the effects of PRP are inconsistent, and its effects on bone union in spinal surgery remain controversial. The immortalized megakaryocyte cell lines (imMKCLs) derived from human-induced pluripotent stem cells (hiPSCs) have been developed to produce numerous stable and clinically functional platelets. In this study, growth factors present in freeze-dried hiPSC-derived imMKCLs and platelets (iPS-MK/Plts) were evaluated, and their ability to promote bone formation was examined using a rat lumbar artificial bone grafting model. METHODS: We prepared freeze-dried iPS-MK/Plts and quantified their growth factors by enzyme-linked immunosorbent assays. Surgical grafting of artificial bone to the lumbar transverse processes was performed in 8-week-old female rats, which were divided into two groups: artificial bone graft (control) and artificial bone graft plus freeze-dried iPS-MK/Plts (iPS group). Transplantation was performed only on the left side. Eight weeks after the surgery, we captured computed tomography images and compared bilateral differences in the bone volume of the graft site in each rat. We also compared the left side/right side bone volume ratio between the two groups. RESULTS: The freeze-dried iPS-MK/Plts contained numerous growth factors. While there was no significant increase in bone volume on the transplanted side than that on the non-grafted side in the control group, bone volume significantly increased on the transplanted side in the iPS group, as evidenced by augmented mean left/right bone volume ratio of the iPS group compared with that of the control group. But the new bone observed in the iPS group was histologically normal. CONCLUSIONS: Freeze-dried hiPSC-derived MKCLs and platelets contain several stable growth factors and have the potential for promoting new bone formation.

Background factors for chronic low back pain resistant to cognitive behavioral therapy.

This study examined the factors that inhibit the therapeutic effects of cognitive behavioral therapy (CBT) and clarify the adaptation judgment criteria of CBT. We included patients with chronic low back pain and allocated them to the adaptation (with visual analog scale [VAS] improvement) or non-adaptation group (without VAS improvement). The patients were analyzed using various psychological tests. CBT improved depressive symptoms and catastrophic thinking; however, they were not correlated with the VAS and did not directly affect low back pain improvement. The non-adaptation group showed an unexplainable/vague sense of anxiety; an excessive focus on searching for pain; a strong intimacy desire; a strong tendency of medical dependency; and fantasy or distortion of the actual experience, especially self-image. Moreover, the patients showed a low ability to objectively express or attribute meaning to pain due to poor language skills, attention-deficit hyperactivity disorder, and emotional value judgment. Individuals with the aforementioned characteristics of pre-CBT psychological tests should select a different treatment approach given the high poor-adaption possibility. Even patients with depressive or anxious symptoms are not necessarily adaptable for CBT. Therefore, pre-CBT tests for treatment suitability are necessary. Future studies should establish a protocol for psychotherapy suitable for the non-adaptation group.