Hitoshi Tonomura

Hyperthermia for the treatment of articular cartilage with osteoarthritis

Osteoarthritis (OA) is one of the most frequent musculoskeletal disorders in the elderly population. OA is characterised by a gradual loss of extracellular matrix in the articular cartilage of joints. OA can only be managed by artificial joint replacement when joint destruction becomes severe. Therefore, it is preferable to administer conservative therapy that is easy, simple and effective in inhibiting OA progression at the early stage. Heat shock protein 70 (Hsp70) has a protective effect on the cartilage and inhibits the apoptosis of chondrocytes. Heat stimulation by microwave to the joints can increase Hsp70 expression in chondrocytes, and at the same time, Hsp70 expression partially enhances matrix metabolism of the cartilage. These findings suggest that hyperthermia can be positively applied to the treatment of OA. Hyperthermia is therefore expected to be an inexpensive and less-invasive conservative therapy for OA.

Induction of chondrogenic phenotype in synovium-derived progenitor cells by intermittent hydrostatic pressure

OBJECTIVE The aim of this study was to investigate the effect of intermittent hydrostatic pressure (IHP) on chondrogenic differentiation of synovium-derived progenitor cells (SPCs). METHODS SPCs, bone marrow-derived progenitor cells and skin fibroblasts from rabbits were subjected to IHP ranging from 1.0 to 5.0 MPa. The mRNA expression of proteoglycan core protein (PG), collagen type II and SOX-9 was examined using real-time reverse transcriptase-polymerase chain reaction (RT-PCR). The production of SOX-9 protein and glycosaminoglycan (GAG) by SPCs was analyzed by Western blot and the dimethylmethylene blue assay. In addition, mitogen-activated protein (MAP) kinase inhibitors for c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and the p38 pathway were used to identify the signal transduction pathways. RESULTS Real-time RT-PCR showed that mRNA expression of PG, collagen type II and SOX-9 was significantly enhanced only in SPCs receiving 5.0 MPa of IHP. The production of SOX-9 protein and GAG by SPCs was also increased by exposure to 5.0 MPa of IHP. These up-regulated expressions were suppressed by pretreatment with an inhibitor of JNK, but not with inhibitors of ERK or p38. CONCLUSION Our results demonstrated that the exposure of SPCs to 5.0 MPa of IHP could facilitate induction of the chondrogenic phenotype by the MAP kinase/JNK pathway. This finding suggests the potential for IHP utilization in regenerative treatments for cartilage injuries or osteoarthritis.

Enhanced expression of interleukin-6, matrix metalloproteinase-13, and receptor activator of NF-κB ligand in cells derived from osteoarthritic subchondral bone

BackgroundThe aim of this study was to clarify the significance of subchondral bone in the pathology of osteoarthritis (OA) by investigating the expression of inflammatory cytokines, proteases, and receptor activator of NF-κB ligand (RANKL)/receptor activator of NF-κB (RANK)/osteoprotegerin (OPG) involved in cartilage degeneration.MethodsSubchondral bone was obtained from 19 patients diagnosed with knee OA and 4 patients diagnosed with femoral neck fracture. Subchondral bone osteoblasts (SBOs) were isolated, and total RNA was extracted. Messenger RNA expression of inflammatory cytokines, proteases, and RANKL/RANK/OPG were analyzed using a real-time reverse transcription-polymerase chain reaction (RT-PCR).ResultsReal-time RT-PCR showed that mRNA expressions of interleukin-6 (IL-6), matrix metalloproteinase-13 (MMP-13), and RANKL were significantly enhanced in OA SBOs compared to SBOs without OA. The expressions of these genes was greater in patients with severe cartilage damage than in those with mild cartilage damage. A high correlation between mRNA expression of IL-6 and that of MMP-13 was found in OA SBOs.ConclusionThe increases in IL-6, MMP-13, and RANKL expression in OA SBOs suggest that in subchondral bone OA progression involves abnormal osseous tissue remodeling, which induces mechanical property changes. Cartilage degeneration in OA may also be due, at least in part, to IL-6 and MMP-13 produced by SBOs. Comprehensive research on these pathological features may lead to the development of more effective therapies for OA by administration of molecules that affect bone remodeling and metabolism.

Combined microwave irradiation and intraarticular glutamine administration-induced HSP70 expression therapy prevents cartilage degradation in a rat osteoarthritis model.

The objective of the present study was to investigate the effects of heat stimulation and glutamine (Gln) on the expression of extracellular matrix genes and heat shock protein 70 (HSP70) in rat articular cartilage in vivo and to determine whether HSP70 expression achieved with a combination of microwave (MW) and Gln suppresses osteoarthritis (OA) progression in a rat OA model. Stimulation at 40 W was assumed to be appropriate in the present study, and the effects of heat treatment at this intensity were evaluated. Articular cartilage was collected at 8 h after heat stimulation and/or intraarticular Gln administration, and total RNA was extracted. The expression of HSP70, aggrecan, and type II collagen was quantified using real‐time RT‐PCR. Cartilage samples from the OA model were subjected to hematoxylin and eosin (HE) and safranin O staining. HSP70 and aggrecan expression was greatest in a group receiving both MW and Gln. In the rat OA model, the severity of OA was significantly milder in a group receiving MW and Gln than in the control group. HSP70, stimulated by the combination of MW heat and Gln, may be involved in the suppression of OA progression.

Hepatocyte growth factor/c-met promotes proliferation, suppresses apoptosis, and improves matrix metabolism in rabbit nucleus pulposus cells in vitro

The etiology of intervertebral disc (IVD) degeneration is closely related to apoptosis and extracellular matrix degradation in nucleus pulposus (NP) cells. These defects in NP cells are induced by excessive external stressors such as reactive oxygen species (ROS) and inflammatory cytokines. Recently, hepatocyte growth factor (HGF) has been shown to repair damage in various diseases through anti‐apoptotic and anti‐inflammatory activity. In this study, we investigated the effects of HGF on NP cell abnormality caused by ROS and inflammatory cytokines by using primary NP cells isolated from rabbit IVD. HGF significantly enhanced the proliferation of NP cells. Apoptosis of NP cells induced by H2O2 or TNF‐α was significantly inhibited by HGF. Induction of mRNA expression of the inflammation mediators cyclooxygenase‐2 and matrix metalloproteinase‐3 and ‐9 by TNF‐α was significantly suppressed by HGF treatment. Expression of c‐Met, a specific receptor for HGF, was confirmed in NP cells and was increased by TNF‐α, suggesting that inflammatory cytokines increase sensitivity to HGF. These findings demonstrate that activation of HGF/c‐Met signaling suppresses damage caused by ROS and inflammation in NP cells through multiple pathways. We further suggest the clinical potential of HGF for counteracting IVD degradation involved in NP cell abnormalities.

Influence of extracellular matrix on the expression of inflammatory cytokines, proteases, and apoptosis-related genes induced by hydrostatic pressure in three-dimensionally cultured chondrocytes

BackgroundThe purpose of this study was to investigate the influence of hydrostatic pressure (HP) on the gene expression of cartilage matrix, cytokines, and apoptosis-associated factors in chondrocytes in which the cartilage was in extracellular matrix (ECM)-rich or ECM-poor condition.MethodsChondrocytes were isolated from rabbit joints and cultured in alginate beads. Immediately after embedding (0W group) or after 2 weeks culture (2W group), the amounts of glycosaminoglycan (GAG) in the alginate beads were quantified. Both groups were exposed to continuous HP of 10 or 50 MPa for 12 h. The expression of inflammatory cytokines, proteases, and apoptosis-related factors were examined by reverse transcription-polymerase chain reaction (RT-PCR). The expression of proteoglycan core protein (PG) and collagen type II were quantified by real-time RT-PCR.ResultsAll of the GAG components in alginate beads markedly increased in the 2W group. The expression of PG and collagen type II increased after exposure to 10 MPa in both groups. In the 0W group, these levels decreased after exposure to 50 MPa of HP. The expression of interleukins IL-6 and IL-8 increased after exposure to HP in the 0W group. HP at 50 MPa induced mRNA expression of ADAMTS-5 in the 0W group but not in the 2W group. The expression of Fas increased after exposure to HP in the 0W group.ConclusionsThese findings suggested that nonphysiological, excessive HP on chondrocytes with the ECM in poor condition reduced matrix gene expression and increased expression of the genes associated with apoptosis and catabolism of the cartilage matrix. These results might therefore be associated with the pathogenesis of osteoarthritis.

Prevention of neurological complications using a neural monitoring system with a finger electrode in the extreme lateral interbody fusion approach

OBJECTIVE Extreme lateral interbody fusion (XLIF) is a minimally disruptive surgical procedure that uses a lateral approach. There is, however, concern about the development of neurological complications when this approach is used, particularly at the L4-5 level. The authors performed a prospective study of the effects of a new neural monitoring system using a finger electrode to prevent neurological complications in patients treated with XLIF and compared the results to results obtained in historical controls. METHODS The study group comprised 36 patients (12 male and 24 female) who underwent XLIF for lumbar spine degenerative spondylolisthesis or lumbar spine degenerative scoliosis at L4-5 or a lower level. Using preoperative axial MR images obtained at the mid-height of the disc at the treated level, we calculated the psoas position value (PP%) by dividing the distance from the posterior border of the vertebral disc to the posterior border of the psoas major muscle by the anteroposterior diameter of the vertebral disc. During the operation, the psoas major muscle was dissected using an index finger fitted with a finger electrode, and threshold values of the dilator were recorded before and after dissection. Eighteen cases in which patients had undergone the same procedure for the same indications but without use of the finger electrode served as historical controls. Baseline clinical and demographic characteristics, PP values, clinical results, and neurological complications were compared between the 2 groups. RESULTS The mean PP% values in the control and finger electrode groups were 17.5% and 20.1%, respectively (no significant difference). However, 6 patients in the finger electrode group had a rising psoas sign with PP% values of 50% or higher. The mean threshold value before dissection in the finger electrode group was 13.1 ± 5.9 mA, and this was significantly increased to 19.0 ± 1.5 mA after dissection (p < 0.001). A strong negative correlation was found between PP% and threshold values before dissection, but there was no correlation with threshold values after dissection. The thresholds after dissection improved to 11 mA or higher in all patients. There were no serious neurological complications in any patient, but there was a significantly lower incidence of transient neurological symptoms in the finger electrode group (7 [38%] of 18 cases vs 5 [14%] of 36 cases, p = 0.047). CONCLUSIONS The new neural monitoring system using a finger electrode may be useful to prevent XLIF-induced neurological complications.

Evaluation of resorption and biocompatibility of collagen hemostats in the spinal epidural space

BACKGROUND CONTEXT Collagen hemostats have different characteristics depending on their properties and configuration. In vivo serial evaluation of local reactions because of placement of hemostats in the epidural space has not been reported. PURPOSE This study compared the resorption and biocompatibility of two types of collagen hemostats placed in the epidural space. STUDY DESIGN This in vivo study used experimental animals to evaluate collagen hemostats that were placed in the epidural space. METHODS A ligamentum flavum resection model was created in Japanese white rabbits (n=65). A microfibrillar collagen hemostat (MCH group, n=5), cotton-type collagen hemostat (CCH group, n=5) that was chemically cross-linked, or no hemostat (control group, n=4) was placed in the spinal epidural space. For histologic evaluation, each group was euthanized 1, 2, 4, and 8 weeks postoperatively (PO), and hematoxylin-eosin and immunohistochemical (IHC) staining for inflammatory cytokines (tumor necrosis factor [TNF]-α, interleukin [IL]-6), cyclooxygenase (COX)-2, and macrophages (CD68) was performed. To evaluate exudate accumulation and the degree of inflammation in the epidural space, magnetic resonance imaging at 7.04 T was serially performed in each group (n=3) under anesthesia and sedation. RESULTS The collagen hemostats in both groups were reabsorbed at 4 weeks PO. In the MCH group, there was inflammatory cell infiltration and granuloma formation around the hemostat, TNF-α-positive cells were seen up to 1 week, and IL-6-, COX-2-, and CD68-positive cells were seen at all evaluation times. In the CCH group, no inflammatory cell infiltration around the hemostat was observed, and IHC staining showed no positive cells at 4 weeks PO and later. T2*-weighted MR images showed significantly higher mean signal intensity of the epidural space in the MCH group than in the CCH group but only at 1 week PO (p<.05). CONCLUSIONS Resorption of both hemostats was similar. In the MCH group, there was intense tissue inflammation around the hemostatic material, and MR images showed high signal intensity because of exudate accumulation in the epidural space. This indicated a strong foreign-body reaction to the MCH, thus demonstrating a difference in biocompatibility with the CCH.

Magnetic Resonance Imaging Evaluation of the Effects of Surgical Invasiveness on Paravertebral Muscles Following Muscle-preserving Interlaminar Decompression (MILD).

Study Design: This is a retrospective study. Objectives: The aim of this study was to determine the extent of damage to the paravertebral muscles after muscle-preserving interlaminar decompression (MILD) using magnetic resonance imaging to evaluate changes in the multifidus muscle (MF). Summary of Background Data: Short-term surgical outcomes of MILD for lumbar spinal canal stenosis (LSCS) are satisfactory; however, the extent of damage to the paravertebral muscles after MILD remains unclear. Methods: Thirty-four patients (18 men/16 women; mean age: 72.6 y) who had LSCS treated with MILD were retrospectively investigated. A total of 61 decompressed disk levels [L2/3(5); L3/4(21); L4/5(30); L5/S(5)] and 34 nondecompressed levels (L1/2) were assessed. There was 1 decompressed disk level in 12 cases, 2 in 17 cases, and 3 in 5 cases. Magnetic resonance imaging scans were obtained before surgery and at 3 and 12–18 months after surgery, using the same scanner. The rate of paravertebral muscle atrophy was evaluated to compare the area of the MF in the T2-weighted axial plane (intervertebral disk level) preoperatively and postoperatively, using OsiriX Medical Imaging Software. Changes in muscle signal intensity were also recorded. Statistical analysis was performed using 3-way analysis of variance with the post hoc Fisher PSLD test. Results: The rate of MF atrophy was 4.0% at the decompressed levels and 2.1% at the nondecompressed levels. There were no changes of signal intensity in the MF between the preoperative and postoperative periods. In decompressed levels, muscle atrophy and signal intensity were significantly improved from 3 months to 12–18 months after surgery. The number and level of the decompressed disks did not affect the extent of muscle injury. Conclusions: The extent of paravertebral muscle injury after MILD is satisfactory. The midline interlaminar approach used in this technique may prevent local denervation and irreversible damage to the paravertebral muscles. These results indicate that MILD is useful to treat LSCS less invasively.

Innovative Technique for the Placement of the Drainage Tube for Microendoscopic Spinal Decompression.

Study Design: A technical note and retrospective study. Objectives: The objectives were to describe a new method of drainage tube placement during microendoscopic spinal decompression, and compare the positioning and fluid discharge obtained with this method and the conventional method. Summary of Background Data: To prevent postoperative epidural hematoma after microendoscopic decompression, a drainage tube must be placed in a suitable location. However, the narrow operative field makes precise control of the position of the tube technically difficult. We developed a method to reliably place the tube in the desired location. Materials and Methods: We use a Deschamps aneurysm needle with a slightly curved tip, which we call a drain passer. With the microendoscope in position, the drain passer, with a silk thread passed through the eye at the needle tip, is inserted percutaneously into the endoscopic field of view. The drainage tube is passed through the loop of silk thread protruding from the inside of the tubular retractor, and the thread is pulled to the outside, guiding the end of the drainage tube into the wound. This method was used in 23 cases at 44 intervertebral levels (drain passer group), and the conventional method in 20 cases at 32 intervertebral levels (conventional group). Postoperative plain radiographs were taken, and the amount of fluid discharge at postoperative hour 24 was measured. Results: Drainage tube positioning was favorable at 43 intervertebral levels (97.7%) in the drain passer group and 26 intervertebral levels (81.3%) in the conventional group. Mean fluid discharge was 58.4±32.2 g in the drain passer group and 38.4±23.0 g in the conventional group. Positioning was significantly better and fluid discharge was significantly greater in the drain passer group. Conclusion: The results indicate that this method is a useful drainage tube placement technique for preventing postoperative epidural hematoma.