Shurei Sugita

Notch signaling in chondrocytes modulates endochondral ossification and osteoarthritis development

Here we examined the involvement of Notch signaling in the endochondral ossification process, which is crucial for osteoarthritis (OA) development. Intracellular domains of Notch1 and -2 were translocated into the nucleus of chondrocytes with their differentiation in mouse limb cartilage and in mouse and human OA articular cartilage. A tissue-specific inactivation of the Notch transcriptional effector recombination signal binding protein for Ig kappa J (RBPjκ) in chondroprogenitor cells of SRY-box containing gene 9 (Sox9)-Cre;Rbpjfl/fl mouse embryos caused an impaired terminal stage of endochondral ossification in the limb cartilage. The RBPjκ inactivation in adult articular cartilage after normal skeletal growth using type II collagen (Col2a1)-CreERT;Rbpjfl/fl mice by tamoxifen injection caused resistance to OA development in the knee joint. Notch intracellular domain with the effector RBPjκ stimulated endochondral ossification through induction of the target gene Hes1 in chondrocytes. Among the Notch ligands, Jagged1 was strongly induced during OA development. Finally, intraarticular injection of N-[N-(3,5-diflurophenylacetate)-l-alanyl]-(S)-phenylglycine t-butyl ester (DAPT), a small compound Notch inhibitor, to the mouse knee joint prevented OA development. The RBPjκ-dependent Notch signaling in chondrocytes modulates the terminal stage of endochondral ossification and OA development, representing an extracellular therapeutic target of OA.

Transcription factor Hes1 modulates osteoarthritis development in cooperation with calcium/calmodulin-dependent protein kinase 2

Significance Here we demonstrate that Hes1, an important target of Notch signaling, modulated pathogenesis of osteoarthritis by using Col2a1-CreERT;Hes1fl/fl mice. Adamts5 and Mmp13, catabolic enzymes that break down cartilage matrix, were induced by Hes1. Additionally, microarray analysis and ChIP-seq revealed novel Hes1 target genes, including Il6 and Il1rl1, coding a receptor for IL-33. CaMK2δ was activated during osteoarthritis development. CaMK2δ formed a protein complex with Hes1, and switched it from a transcriptional repressor to a transcriptional activator to induce cartilage catabolic factors. Notch signaling modulates skeletal formation and pathogenesis of osteoarthritis (OA) through induction of catabolic factors. Here we examined roles of Hes1, a transcription factor and important target of Notch signaling, in these processes. SRY-box containing gene 9 (Sox9)-Cre mice were mated with Hes1fl/fl mice to generate tissue-specific deletion of Hes1 from chondroprogenitor cells; this deletion caused no obvious abnormality in the perinatal period. Notably, OA development was suppressed when Hes1 was deleted from articular cartilage after skeletal growth in type II collagen (Col2a1)-CreERT;Hes1fl/fl mice. In cultured chondrocytes, Hes1 induced metallopeptidase with thrombospondin type 1 motif, 5 (Adamts5) and matrix metalloproteinase-13 (Mmp13), which are catabolic enzymes that break down cartilage matrix. ChIP-seq and luciferase assays identified Hes1-responsive regions in intronic sites of both genes; the region in the ADAMTS5 gene contained a typical consensus sequence for Hes1 binding, whereas that in the MMP13 gene did not. Additionally, microarray analysis, together with the ChIP-seq, revealed novel Hes1 target genes, including Il6 and Il1rl1, coding a receptor for IL-33. We further identified calcium/calmodulin-dependent protein kinase 2δ (CaMK2δ) as a cofactor of Hes1; CaMK2δ was activated during OA development, formed a protein complex with Hes1, and switched it from a transcriptional repressor to a transcriptional activator to induce cartilage catabolic factors. Therefore, Hes1 cooperated with CaMK2δ to modulate OA pathogenesis through induction of catabolic factors, including Adamts5, Mmp13, Il6, and Il1rl1. Our findings have contributed to further understanding of the molecular pathophysiology of OA, and may provide the basis for development of novel treatments for joint disorders.

Intraoperative ultrasonographic evaluation of posterior decompression via laminoplasty in patients with cervical ossification of the posterior longitudinal ligament: correlation with 2-year follow-up results

OBJECT The aim in this prospective study was to determine the morphological limitations of laminoplasty for cervical ossification of the posterior longitudinal ligament (OPLL) by using intraoperative ultrasonography and to investigate correlations between ultrasonographic findings and 2-year follow-up results. METHODS Included in this study were 40 patients who underwent double-door laminoplasty for cervical myelopathy due to OPLL. Intraoperative ultrasonography was used to evaluate posterior shift of the spinal cord after the posterior decompression procedure. To determine the decompression status of the cord, the authors classified ultrasonographic findings into 3 types on the basis of the presence or absence of spinal cord contact with OPLL after decompression: Type 1, noncontact; Type 2, contact and apart; and Type 3, contact. Patients were divided accordingly into Group 1, showing Type 1 or 2 findings, representing sufficient decompression; and Group 2, showing Type 3 findings with insufficient decompression. Preoperative sagittal alignment of the cervical spine (C2-7 angle) and preoperative maximal thickness of OPLL were compared between groups. The authors also investigated the morphological limitations of laminoplasty and 2-year follow-up results by using the Japanese Orthopedic Association (JOA) scoring system. RESULTS According to receiver operating characteristic curve analysis, an OPLL maximal thickness > 7.2 mm was a cutoff value for insufficient decompression. However, sufficient or insufficient decompression did not correlate with 2-year results, as determined by JOA scores. The C2-7 angle had no impact on ultrasonographic findings. CONCLUSIONS Laminoplasty has a morphological limitation for thick OPLLs, and a thickness > 7.2 mm represents a theoretical cutoff for residual cord compression after laminoplasty. According to 2-year results, however, laminoplasty can remain the first choice for any type of multiple-level OPLL.

Regulation of Chondrocyte Survival in Mouse Articular Cartilage by p63

Transcription factor p63, of the p53 family, regulates cell proliferation, survival, and apoptosis in various cells and tissues. This study was undertaken to examine the expression and roles of p63 transcript variants in the mouse growth plate and articular chondrocytes.

p63 Regulates Chondrocyte Survival in Articular Cartilage

Transcription factor p63, of the p53 family, regulates cell proliferation, survival, and apoptosis in various cells and tissues. This study was undertaken to examine the expression and roles of p63 transcript variants in the mouse growth plate and articular chondrocytes.

Hand-Held Bone Cutting Tool With Autonomous Penetration Detection for Spinal Surgery

In spinal surgery, a surgeon often needs to remove some parts of the spine to relieve the pressure on the spinal cord or other nerves. In this procedure, the surgeon needs to cut and drill some holes in the spine. This operation is very risky because there are some nerves beneath the target bones, and this procedure therefore requires a skilled and experienced surgeon. However, if the cutting tool could detect penetration of the bone autonomously, the safety of the procedure would be improved drastically. This study presents a hand-held bone cutting tool system that detects the penetration of the workpiece. The system learns the cutting states and motion states from demonstrations by a surgeon, and it autonomously detects the penetration of the workpiece and stops the actuation of the cutting tool immediately before total penetration. The proposed scheme for penetration detection does not require knowledge of the shape and the position of the workpiece and, therefore, it does not require any costly systems, such as robotic arms and position sensor systems. In addition, the proposed scheme can be easily applied to various shapes of the cutting tool, such as drills and saws. The developed system was evaluated through experiments. The results showed that the performance of the developed system was satisfactory in both a motorized and a hand-held setup.

Optimal treatment for Spinal Cord Injury associated with cervical canal Stenosis (OSCIS): a study protocol for a randomized controlled trial comparing early versus delayed surgery

BackgroundThe optimal management of acute cervical spinal cord injury (SCI) associated with preexisting canal stenosis remains to be established. The objective of this study is to examine whether early surgical decompression (within 24 hours after admission) would result in greater improvement in motor function compared with delayed surgery (later than two weeks) in cervical SCI patients presenting with canal stenosis, but without bony injury.Methods/designOSCIS is a randomized, controlled, parallel-group, assessor-blinded, multicenter trial. We will recruit 100 cervical SCI patients who are admitted within 48 hours of injury (aged 20 to 79 years; without fractures or dislocations; American Spinal Injury Association (ASIA) grade C; preexisting spinal canal stenosis). Patients will be enrolled from 36 participating hospitals across Japan and randomly allocated in a 1:1 ratio to either early surgical decompression (within 24 hours after admission) or delayed surgery following at least two weeks of conservative treatment. The primary outcomes include: 1) the change from baseline to one year in the ASIA motor score; 2) the total score of the Spinal Cord Independence Measure and 3) the proportion of patients who are able to walk without human assistance. The secondary outcomes are: 1) the health-related quality of life as measured by the Medical Outcomes Study Short Form 36 and the EuroQol 5 Dimension; 2) the Neuropathic Pain Symptom Inventory and 3) the walking status as evaluated with the Walking Index for Spinal Cord Injury II. The analysis will be on an intention-to-treat basis. The primary analysis will be a comparison of the primary and secondary outcomes one year after the injury.DiscussionThe results of this study will provide evidence of the potential benefit of early surgical decompression compared to the current ‘watch and wait’ strategy.Trial registrationUMIN000006780; NCT01485458

Autonomous penetration detection for bone cutting tool using demonstration-based learning

In orthopedic surgery, bone-cutting procedures are frequently performed. However, bone-cutting procedures are very risky in cases where vital organs or nerves exist beneath the target bones. In such cases, surgeons are required to determine the depth of the penetration into the bone by using only their haptic senses. Thus, we developed a handheld bone-cutting-tool system that detects the penetration of the cutting material. The developed system autonomously detects the penetration before total penetration and stops the actuation of the cutting tool, leaving a very thin remnant of work material. The developed system estimates the cutting resistance by using its motors current and rotational speed. On the basis of data collected preoperatively, the system estimates the cutting state by using a support vector machine (SVM). According to the SVM outputs, the system detects the penetration of the work material and autonomously stops the actuation of the cutting tool. The proposed method was verified through experiments, and the results showed that the developed system successfully detected the penetrations of work materials and stopped autonomously immediately before total penetration. This study showed that the autonomous detection of bone penetration with a hand-held bone-cutting tool is feasible by using the proposed scheme.

Is a right pedicle screw always away from the aorta in scoliosis

Study Design. Retrospective analysis. Objective. We evaluated the aorta safety in placement of a right pedicle screw in scoliotic patients. Summary of Background Data. Past reports emphasized the aorta risk in placing pedicle screws on the concave left side in right thoracic scoliosis. However, risk on the right side has drawn limited interest. Methods. Thirty-four scoliotic patients with an average age of 18.0 years were evaluated. The Cobb angle averaged 59.0° ± 14.0°. From computed tomographic data, we evaluated the aorta location relative to the spine at each level from T4 to L4 and simulated placement of a right pedicle screw with a direction different from the ideal trajectory. Sensitivity analysis was performed independently by variable direction errors and screw length: the maximum error of trajectory was set to 5° in the medial direction and to 5°, 10°, or 20° in the lateral direction, and a screw length was set at 40, 45 or 50 mm. We defined “aorta-at-risk” when a patient has some level where a simulated pedicle screw involves the aorta, and compared the curve characteristics (the apical vertebral translation, the Cobb angle and the Nash-Moe grade) between the aorta-at-risk cases and the aorta-no-risk cases. Results. In left thoracic or lumbar curves, the aorta often resided in front of right pedicles at the periapical level. In a scenario of a simulated pedicle screw with a maximum error of 20° in the lateral direction and a screw length of 50 mm, the aorta was at risk in 7 (33%) of 21 left lumbar curves. Curve characteristics of the aorta-at-risk cases at L1 were a larger apical vertebral translation (P = 0.003), a larger Cobb angle (P = 0.006), and a larger Nash-Moe grade (P = 0.017) compared with those of the aorta-no-risk cases. Conclusion. Surgeons need to pay attention to the position of the aorta in placing a pedicle screw on the right at the periapical level of a left curve either in thoracic or lumbar spine.

Ossification of the posterior atlantoaxial membrane associated with an os odontoideum: a case report.

We report a case of ossification of the posterior atlantoaxial membrane associated with an os odontoideum in a 46-year-old woman. She developed myelopathy following a minor motor vehicle accident. The patient underwent posterior atlantoaxial arthrodesis and resection of the ossified lesion and recovered uneventfully. Long-standing atlantoaxial instability might have played a role in ectopic ossification of the posterior atlantoaxial membrane.