Interactive parallel sex pheromone circuits that promote and suppress courtship behaviors in the cockroach.

Many animals use multicomponent sex pheromones for mating, but the specific function and neural processing of each pheromone component remain unclear. The cockroach Periplaneta americana is a model for studying sex pheromone communication, and an adult female emits major and minor sex pheromone components, periplanone-B and -A (PB and PA), respectively. Attraction and courtship behaviors (wing-raising and abdominal extension) are strongly expressed when adult males are exposed to PB but weakly expressed when they are exposed to PA. When major PB is presented together with minor PA, behaviors elicited by PB were impaired, indicating that PA can both promote and suppress courtship behaviors depending on the pheromonal context. In this study, we identified the receptor genes for PA and PB and investigated the effects of knocking down each receptor gene on the activities of PA- and PB-responsive sensory neurons (PA- and PB-SNs), and their postsynaptic interneurons, and as well as effects on courtship behaviors in males. We found that PB strongly and PA weakly activate PB-SNs and their postsynaptic neurons, and activation of the PB-processing pathway is critical for the expression of courtship behaviors. PA also activates PA-SNs and the PA-processing pathway. When PA and PB are simultaneously presented, the PB-processing pathway undergoes inhibitory control by the PA-processing pathway, which weakens the expression of courtship behaviors. Our data indicate that physiological interactions between the PA- and PB-processing pathways positively and negatively mediate the attraction and courtship behaviors elicited by sex pheromones.

Parallel olfactory processing in a hemimetabolous insect.

To represent specific olfactory cues from the highly complex and dynamic odor world in the brain, insects employ multiple parallel olfactory pathways that process odors with different coding strategies. Here, we summarize the anatomical and physiological features of parallel olfactory pathways in the hemimetabolous insect, the cockroach Periplaneta americana. The cockroach processes different aspects of odor stimuli, such as odor qualities, temporal information, and dynamics, through parallel olfactory pathways. These parallel pathways are anatomically segregated from the peripheral to higher brain centers, forming functional maps within the brain. In addition, the cockroach may possess parallel pathways that correspond to distinct types of olfactory receptors expressed in sensory neurons. Through comparisons with olfactory pathways in holometabolous insects, we aim to provide valuable insights into the organization, functionality, and evolution of insect olfaction.

Cuticular hydrocarbon reception by sensory neurons in basiconic sensilla of the Japanese carpenter ant.

To maintain the eusociality of a colony, ants recognize subtle differences in colony-specific sets of cuticular hydrocarbons (CHCs). The CHCs are received by female-specific antennal basiconic sensilla and processed in specific brain regions. However, it is controversial whether a peripheral or central neural mechanism is mainly responsible for discrimination of CHC blends. In the Japanese carpenter ant, Camponotus japonicus, about 140 sensory neurons (SNs) are co-housed in a single basiconic sensillum and receive colony-specific blends of 18 CHCs. The complexity of this CHC sensory process makes the neural basis of peripheral nestmate recognition difficult to understand. Here, we electrophysiologically recorded responses of single basiconic sensilla to each of 18 synthesized CHCs, and identified CHC responses of each SN co-housed in a single sensillum. Each CHC activated different sets of SNs and each SN was broadly tuned to CHCs. Multiple SNs in a given sensillum fired in synchrony, and the synchronicity of spikes was impaired by treatment with a gap junction inhibitor. These results indicated that SNs in single basiconic sensilla were electrically coupled. Quantitative analysis indicated that the Japanese carpenter ants have the potential to discriminate chemical structures of CHCs based on the combinational patterns of activated SNs. SNs of ants from different colonies exhibited different CHC response spectra. In addition, ants collected from the same colony but bred in separate groups also exhibited different CHC response spectra. These results support the hypothesis that the peripheral sensory mechanism is important for discrimination between nestmate and non-nestmate ants.

Silencing the odorant receptor co-receptor impairs olfactory reception in a sensillum-specific manner in the cockroach.

Insects detect odors via a large variety of odorant receptors (ORs) expressed in olfactory sensory neurons (OSNs). The insect OR is a heteromeric complex composed of a ligand-specific receptor and the co-receptor (ORco). In this study, we identified the ORco gene of the cockroach, Periplaneta americana (PameORco), and performed RNAi-based functional analysis of PameORco. All OSNs in the basiconic sensilla expressed PameORco and received a large variety of odors including sex pheromones. In trichoid sensilla, a PameORco-positive OSN was consistently paired with a PameORco-negative OSN tuned to acids. In adult cockroaches injected with PameORco dsRNA at the nymphal stage, the expression of PameORco, odor receptions via ORs, and its central processing were strongly suppressed. These results provide new insights into the molecular basis of olfactory reception in the cockroach. The long-lasting and irreversible effects of PameORco RNAi would be an effective method for controlling the household pest.

Two-level Posterior Lumbar Interbody Fusion at the Lumbosacral Segment has a High Risk of Pseudarthrosis and Poor Clinical Outcomes: Comparison Between the Lumbar and Lumbosacral Segments.

STUDY DESIGN: This was a retrospective study. OBJECTIVES: The purposes of this study were to investigate the fusion rate and clinical outcomes of 2-level posterior lumbar interbody fusion (PLIF). SUMMARY OF BACKGROUND DATA: PLIF provides favorable clinical outcomes and a high fusion rate. However, most extant studies have been limited to the results of single-level PLIF. Clinical outcomes and fusion rate of 2-level PLIF are unknown. MATERIALS AND METHODS: In total, 73 patients who underwent 2-level PLIF below L3 between 2008 and 2016 (follow-up period >2 y) were included. Patients were divided into the 2 groups on the basis of surgical level. The lumbar group included 48 patients who underwent L3/4/5 PLIF, and the lumbosacral group included 25 patients who underwent L4/5/S PLIF. Fusion rate and clinical outcomes were compared. The Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and a visual analog scale were used for evaluation. RESULTS: Fusion rate was significantly lower in the lumbosacral group (lumbar 96% vs. lumbosacral 64%; P<0.001). Eight of 9 cases of pseudarthrosis occurred at the lumbosacral segment. Improvement in the mental health domain of the JOAPEQ was significantly lower in the lumbosacral group (lumbar 16 vs. lumbosacral 10; P=0.02). The VAS data showed that improvements in the following variables were significantly lower in the lumbosacral group than in the lumbar group: pain in low back (lumbar -38 vs. lumbosacral -23; P=0.004), pain in buttocks or lower leg (lumbar -48 vs. lumbosacral -29; P=0.04), and numbness in buttocks or lower leg (lumbar -44 vs. lumbosacral -33; P=0.04). CONCLUSIONS: Two-level PLIF at the lumbosacral segment demonstrated a significantly lower fusion rate and poorer clinical outcomes than that at the lumbar-only segments. Some reinforcement for the sacral anchor is recommended to improve fusion rate, even for short fusion like 2-level PLIF, if the lumbosacral segment is included. LEVEL OF EVIDENCE: Level III.

Sensory neurons that respond to sex and aggregation pheromones in the nymphal cockroach.

In the common pest cockroach, Periplaneta americana, behavioural responses to the sex and aggregation pheromones change in an age-dependent manner. Nymphs are attracted by the aggregation pheromone periplanolide-E (PLD-E) but not by the sex pheromone periplanone-B (PB) in faeces. Adults display prominent behaviours to PB but not to PLD-E. Despite the significant behavioural differences depending on postembryonic developmental stages, peripheral codings of the sex and aggregation pheromones have not been studied in the nymph of any insects as far as we know. In this study, we morphologically and electrophysiologically identified antennal sensilla that respond to PB and PLD-E in nymphal cockroaches. Although nymphs lacked the sex pheromone-responsive single-walled B (sw-B) sensilla identified in adult males, we found PB-responsive sensory neurons (PB-SNs) within newly identified sw-A2 sensilla, which exhibit different shapes but have the same olfactory pores as sw-B sensilla. Interestingly, PLD-E-responsive sensory neurons (PLD-E-SNs) were also identified in the same sensillar type, but PB and PLD-E were independently detected by different SNs. Both PB-SNs and PLD-E-SNs showed high sensitivity to their respective pheromones. The hemimetabolous insect nymph has an ability to detect these pheromones, suggesting that behaviours elicited by pheromones might be established in brain centres depending on postembryonic development.

Two types of sensory proliferation patterns underlie the formation of spatially tuned olfactory receptive fields in the cockroach Periplaneta americana.

In the cockroach Periplaneta americana, to represent pheromone source in the receptive space, axon terminals of sex pheromone-receptive olfactory sensory neurons (pSNs) are topographically organized within the primary center, the macroglomerulus, according to the peripheral locations of sex pheromone-receptive single walled (sw)-B sensilla. In this study, we sought to determine when and where pSNs emerge in the nymphal antenna. We revealed two different pSN proliferation patterns that underlie the formation of topographic organization in the macroglomerulus. In nymphal antennae, which lack sw-B sensilla, pSNs are identified in the shorter sensilla, termed sw-A sensilla. Because new sw-A sensilla emerge on the proximal antenna at every molt, topographic organization in the macroglomerulus must be formed by adding axon terminals of newly emerged pSNs to the lateral region in the macroglomerulus at each molt. At the final molt, a huge number of new sw-B sensilla appeared throughout the whole antenna. Sw-B sensilla in the proximal part of the adult antenna were newly formed during the last instar stage, whereas those located in the distal antenna were transformed from sw-A sensilla. This transformation was accompanied by an increase in the number of pSNs. Axon terminals of newborn pSNs in new sw-B sensilla were recruited to the lateral part of the macroglomerulus, whereas those of newborn pSNs in transformed sw-B sensilla were recruited to the macroglomerulus according to the sensillar location. These mechanisms enable an increase in sensitivity to sex pheromone in adulthood while retaining the topographic map formed during the postembryonic development.

Conventional JOA score for cervical myelopathy has a rater's bias -In comparison with JOACMEQ.

BACKGROUND: The JOA (Japan Orthopaedic Association) score has been a standard outcome measure to evaluate cervical myelopathy in Japan. Despite its reliability and convenience, there can be a rating bias in the JOA score. The current study was conducted to delineate the rater's bias of the JOA score by comparing it with a new objective outcome measure. METHODS: Two hundred and thirty four operative candidates with cervical myelopathy were included in the study. The patients were divided into four groups according to the surgeon (92 patients in group A, 60 patients in group B, 38 patients in group C and 44 patients in group D). Each patient's preoperative JOA score was exclusively recorded by the surgeon himself, while JOACMEQ (Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire) was recorded by each patient. Disease severity, the most important prognostic factor, was equalized between patient groups by a special statistical method called inverse-probability weighting (IPW). To define similarity of the two groups, Cohen's d was used. RESULTS: After the adjustment, the differences of the JOA score were only 0.1 between groups A and D and 0 between groups B and C. The values of Cohen's d were also very small both between groups A and D (3%), and between groups B and C (0.3%). The averaged JOA scores of groups A and D were higher by 0.4-0.8 than those of groups B and C, while the averaged JOA scores were almost the same both between groups A and D, and between groups B and C. Surgeons A and D had the same tendency to give higher JOA scores than surgeons B and C did. CONCLUSIONS: The current study confirmed there is a definite rater's bias in the JOA score. JOACMEQ is to be applied as a more reliable outcome measure to evaluate myelopathy patients.

Clinical Outcomes After Posterior Lumbar Interbody Fusion: Comparison of Cortical Bone Trajectory and Conventional Pedicle Screw Insertion.

STUDY DESIGN: This study is a retrospective cohort study using prospectively collected data. OBJECTIVE: To compare the effectiveness of posterior lumbar interbody fusion (PLIF) using the cortical bone trajectory (CBT) and conventional pedicle screw (PS) techniques. SUMMARY OF BACKGROUND DATA: There are few published studies to date comparing PLIF using CBT technique with PLIF using the conventional PS technique. METHODS: We studied 119 consecutive patients who underwent single-level PLIF between 2010 and 2014 with a minimum 12-month follow-up. Forty-two patients underwent CBT-PLIF (the CBT group) and 77 underwent conventional PS-PLIF (the PS group). Clinical outcomes were assessed by the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and visual analog scale (VAS). To assess perioperative pain, a 6-point Numeric Rating Scale score and the total amount of diclofenac sodium suppositories used were recorded. The operative time and blood loss were recorded. Muscle damage was evaluated by serum creatine kinase concentrations. Fusion status was evaluated using 3-dimensional computed tomography 12 months postoperatively. We used inverse probability of treatment weighting based on the propensity score to reduce confounding factors. RESULTS: There were no significant between-group differences in operative time or fusion rates, whereas the CBT group experienced significantly less blood loss, lower postoperative creatine kinase levels, less diclofenac sodium suppositories, and lower Numeric Rating Scale scores than the PS group did. The change in the JOABPEQ subdomain score for social life function 1 month postoperatively was the only significantly different factor among the JOABPEQ and VAS scores. CONCLUSIONS: Both procedures were comparable in terms of clinical outcomes and fusion rates, but CBT-PLIF provided the additional benefits of less blood loss, less intraoperative muscle damage, less perioperative pain, and earlier recovery to normal activities.

Preoperative retrolisthesis as a predictive risk factor of reoperation due to delayed-onset symptomatic foraminal stenosis after central decompression for lumbar canal stenosis without fusion.

BACKGROUND CONTEXT: For patients diagnosed with lumbar central canal stenosis with asymptomatic foraminal stenosis (FS), surgeons occasionally only decompress central stenosis and preserve asymptomatic FS. These surgeries have the potential risk of converting preoperative asymptomatic FS into symptomatic FS postoperatively by accelerating spinal degeneration, which requires reoperation. However, little is known about delayed-onset symptomatic FS postoperatively. PURPOSE: This study aimed to evaluate the rate of reoperation for delayed-onset symptomatic FS after lumbar central canal decompression in patients with preoperative asymptomatic FS, and determine the predictive risk factors of those reoperations. STUDY DESIGN: This study is a retrospective cohort study. PATIENT SAMPLE: Two hundred eight consecutive patients undergoing posterior central decompression for lumbar canal stenosis between January 2009 and June 2014 were included in this study. OUTCOME MEASURES: The number of patients who had preoperative FS and the reoperation rate for delayed-onset symptomatic FS at the index levels were the outcome measures. METHODS: Patients were divided into two groups with and without preoperative asymptomatic FS at the decompressed levels. The baseline characteristics and revision rates for delayed-onset symptomatic FS were compared between the two groups. Predictive risk factors for such reoperations were determined using multivariate logistic regression and receiver operating characteristics analyses. RESULTS: Preoperatively, 118 patients (56.7%) had asymptomatic FS. Of those, 18 patients (15.3%) underwent reoperation for delayed-onset symptomatic FS at a mean of 1.9 years after the initial surgery. Posterior slip in neutral position and posterior extension-neutral translation were significant risk factors for reoperation due to FS. The optimal cutoff values of posterior slip in neutral position and posterior extension-neutral translation for predicting the occurrence of such reoperations were both 1 mm; 66.7% of patients who met both of these cutoff values had undergone reoperation. CONCLUSIONS: This study demonstrated that 15.3% of patients with preoperative asymptomatic FS underwent reoperation for delayed-onset symptomatic FS at the index levels at a mean of 1.9 years after central decompression, and preoperative retrolisthesis was a predictive risk factor for such a reoperation. These findings are valuable for establishing standards of appropriate treatment strategies in patients with lumbar central canal stenosis with asymptomatic FS.

Preoperative retrolisthesis as a risk factor of postdecompression lumbar disc herniation.

OBJECT: In this study, the authors aimed to identify specific risk factors for postdecompression lumbar disc herniation (PDLDH) in patients who have not undergone discectomy and/or fusion. METHODS: Between 2007 and 2012, 493 patients with lumbar spinal stenosis underwent bilateral partial laminectomy without discectomy and/or fusion in a single hospital. Eighteen patients (herniation group [H group]: 15 men, 3 women; mean age 65.1 years) developed acute sciatica as a result of PDLDH within 2 years after surgery. Ninety patients who did not develop postoperative acute sciatica were selected as a control group (C group: 75 men, 15 women; mean age 65.4 years). Patients in the C group were age and sex matched with those in the H group. The patients in the groups were also matched for decompression level, number of decompression levels, and surgery date. The radiographic variables measured included percentage of slippage, intervertebral angle, range of motion, lumbar lordosis, disc height, facet angle, extent of facet removal, facet degeneration, disc degeneration, and vertebral endplate degeneration. The threshold for PDLDH risk factors was evaluated using a continuous numerical variable and receiver operating characteristic curve analysis. The area under the curve was used to determine the diagnostic performance, and values greater than 0.75 were considered to represent good performance. RESULTS: Multivariate analysis revealed that preoperative retrolisthesis during extension was the sole significant independent risk factor for PDLDH. The area under the curve for preoperative retrolisthesis during extension was 0.849; the cutoff value was estimated to be a retrolisthesis of 7.2% during extension. CONCLUSIONS: The authors observed that bilateral partial laminectomy, performed along with the removal of the posterior support ligament, may not be suitable for lumbar spinal stenosis patients with preoperative retrolisthesis greater than 7.2% during extension.

Vertebral osteolytic defect due to cellulose particles derived from gauze fibers after posterior lumbar interbody fusion.

Vertebral cystic lesions may be observed in pseudarthroses after lumbar fusion surgery. The authors report a rare case of pseudarthrosis after spinal fusion, accompanied by an expanding vertebral osteolytic defect induced by cellulose particles. A male patient originally presented at the age of 69 years with leg and low-back pain caused by a lumbar isthmic spondylolisthesis. He underwent a posterior lumbar interbody fusion, and his neurological symptoms and pain resolved within a year but recurred 14 months after surgery. Radiological imaging demonstrated a cystic lesion on the inferior endplate of L-5 and the superior endplate of S-1, which rapidly enlarged into a vertebral osteolytic defect. The patient underwent revision surgery, and his low-back pain resolved. A histopathological examination demonstrated foreign body-type multinucleated giant cells, containing 10-µm particles, in the sample collected just below the defect. Micro-Fourier transform infrared spectroscopy revealed that the foreign particles were cellulosic, presumably originating from cotton gauze fibers that had contaminated the interbody cages used during the initial surgery. Vertebral osteolytic defects that occur after interbody fusion are generally presumed to be the result of infection. This case suggests that some instances of vertebral osteolytic defects may be aseptically induced by foreign particles. Hence, this possibility should be carefully considered in such cases, to help prevent contamination of the morselized bone used for autologous grafts by foreign materials, such as gauze fibers.

Repair of meniscal lesions using a scaffold-free tissue-engineered construct derived from allogenic synovial MSCs in a miniature swine model.

The menisci of the knee are fibro-cartilaginous tissues and play important roles in the joint, and the loss of the meniscus predisposes the knee to degenerative changes. However, the menisci have limited healing potential due to the paucity of vascularity. The purpose of the present study was to test the feasibility of a scaffold-free tissue-engineered construct (TEC) derived from synovial mesenchymal stem cells (MSCs) to repair incurable meniscal lesions. Porcine synovial MSCs were cultured in monolayers at high density in the presence of ascorbic acid followed by the suspension culture to develop a three-dimensional cell/matrix construct (TEC). A 4-mm cylindrical defect was created bilaterally in the medial meniscus of skeletally mature miniature pigs. The defects were implanted with an allogenic TEC or were left empty. After 6 months, the TEC-treated defects were consistently repaired by a fibro-cartilaginous tissue with good tissue integration to the adjacent host meniscal tissue, while the untreated were either partially or not repaired. The ratio of Safranin O positive area within the central body of the meniscus adjacent to the original defect was significantly higher in the TEC-treated group than in the control group. Moreover, TEC treatment significantly reduced the size and severity of post-traumatic chondral lesions on the tibial plateau. These results suggest that the TEC could be a promising stem cell-based implant to repair meniscal lesions with preventive effects from meniscal body degeneration and the development of post-traumatic arthritis.

The influence of skeletal maturity on allogenic synovial mesenchymal stem cell-based repair of cartilage in a large animal model.

One of the potential factors that may affect the results of mesenchymal stem cell (MSC)-based therapy is the age of donors and recipients. However, there have been no controlled studies to investigate the influence of skeletal maturity on the MSC-based repair of cartilage. The purpose of this study was to compare the repair quality of damaged articular cartilage treated by a scaffold-free three-dimensional tissue-engineered construct (TEC) derived from synovial MSCs between immature and mature pigs. Synovial MSCs were isolated from immature and mature pigs and the proliferation and chondrogenic differentiation capacities were compared. The TEC derived from the synovial MSCs were then implanted into equivalent chondral defects in the medial femoral condyle of both immature and mature pigs, respectively. The implanted defects were morphologically and biomechanically evaluated at 6 months postoperatively. There was no skeletal maturity-dependent difference in proliferation or chondrogenic differentiation capacity of the porcine synovial MSCs. The TEC derived from synovial MSCs promoted the repair of chondral lesion in both immature and mature pigs without the evidence of immune reaction. The repaired tissue by the TEC also exhibited similar viscoelastic properties to normal cartilage regardless of the skeletal maturity. The results of the present study not only suggest the feasibility of allogenic MSC-based cartilage repair over generations but also may validate the use of immature porcine model as clinically relevant to test the feasibility of synovial MSC-based therapies in chondral lesions.

Scaffold-free tissue-engineered construct-hydroxyapatite composites generated by an alternate soaking process: potential for repair of bone defects.

Mesenchymal stem cell (MSC)-based tissue-engineered construct (TEC)-hydroxyapatite (HAp) composites were developed by an alternate soaking process. The TEC derived from cultured synovial MSCs was alternately immersed in varying concentrations of CaCl(2)/Tris-HCl and Na(2)HPO(4)/Tris-HCl buffers, and HAp formation was analyzed by Fourier transform infrared spectroscopy (FT-IR), wide-angle X-ray diffraction, and scanning electron microscopy (SEM). These analyses clearly demonstrated HAp formation in the TEC. Specifically, SEM assessments showed that spherical HAp crystals of approximately 1 mum were directly formed on the surfaces of the cells and extracellular matrix (ECM) fibers. Cytotoxicity from exposure to calcium or phosphate buffers of >100 mM concentrations as assessed by LIVE/DEAD staining and total DNA assays was detected, but such cytotoxicity was not detected following exposure to concentrations of <50 mM. The HAp nanocrystals (ca. approximately 500 nm) were formed after 20 cycles in 10 mM calcium or phosphate buffers, and cell survival in the composites was confirmed. Moreover, preliminary implantation of TEC-HAp composites derived from rabbit synovial MSCs to rabbit osteochondral defects exhibited accelerated osteoinduction. These composites may be the first example of a hybrid material that consists of ECM, HAp nanocrystals, and living MSCs, and the TEC-HAp composite could be a unique and useful material for bone tissue engineering.

A comparison between injection speed and iodine delivery rate in contrast-enhanced computed tomography (CT) for normal beagles.

The purpose of this study was to compare between the injection speed and iodine delivery rate in order to establish a concept for reproducible contrast timing in contrast-enhanced computed tomography (CT) for small animals. Clinically healthy beagle dogs were administered a nonionic iodinate contrast medium at a dose of 800 mgI/kg; they were divided into 3 groups (n=5, crossover method): in one group, the injection speed was fixed at 1.0 ml/sec, and in the second and third groups, the iodine delivery rate was fixed (the injection durations were 30 and 60 sec, respectively). The variation in scatter of the time to aortic and hepatic peak enhancement in the fixed iodine delivery groups was lower than that in the fixed injection speed group. These results suggest that in contrast-enhanced CT for small animals, the contrast medium should be injected at a fixed iodine delivery rate in order to provide reproducible contrast timing.

In vitro generation of a scaffold-free tissue-engineered construct (TEC) derived from human synovial mesenchymal stem cells: biological and mechanical properties and further chondrogenic potential.

The purpose of this study was to characterize a tissue-engineered construct (TEC) generated with human synovial mesenchymal stem cells (MSCs). MSCs were cultured in medium with ascorbic acid 2-phosphate (Asc-2P) and were subsequently detached from the substratum. The detached cell/matrix complex spontaneously contracted to develop a basic TEC. The volume of the TEC assessed by varying initial cell density showed that it was proportional to initial cell densities up to 4 x 10(5) cells/cm(2). Assessment of the mechanical properties of TEC using a custom device showed that the load at failure and stiffness of the constructs significantly increased with time of culture in the presence of Asc-2P, while in the absence of Asc-2P, the constructs were mechanically weak. Thus, the basic TEC possesses sufficiently self-supporting mechanical properties in spite of not containing artificial scaffolding. TEC further cultured in chondrogenic media exhibited positive alcian blue staining with elevated expression of chondrogenic marker genes. Based on these findings, such human TEC may be a promising method to promote cartilage repair for future clinical application.

Cartilage repair using an in vitro generated scaffold-free tissue-engineered construct derived from porcine synovial mesenchymal stem cells.

The objective was to in vitro generate a mesenchymal stem cell (MSC)-based tissue-engineered construct (TEC) to facilitate in vivo repair in a porcine chondral defect model. Porcine synovial MSCs were cultured in monolayer at high density and were subsequently detached from the substratum. The cell/matrix complex spontaneously contracted to develop a basic TEC. Immunohistochemical analysis showed that the basic TEC contained collagen I and III, fibronectin, and vitronectin. The basic TEC exhibited stable adhesion to the surface of a porcine cartilage matrix in an explant culture system. The TEC cultured in chondrogenic media exhibited elevated expression of glycosaminoglycan and chondrogenic marker genes. The TEC were implanted in vivo into chondral defects in the medial femoral condyle of 4-month-old pigs, followed by sacrifice after 6 months. Implantation of a TEC into chondral defects initiated repair with a chondrogenic-like tissue, as well as secure biological integration to the adjacent cartilage. Histologically, the repair tissue stained positively with Safranin O and for collagen II. Biomechanical evaluation revealed that repair tissue exhibited mechanical properties similar to those of normal porcine cartilage in static compression and friction tests. This technology is a unique and promising method for stem cell-based cartilage repair.

Imatinib mesylate inhibits osteoclastogenesis and joint destruction in rats with collagen-induced arthritis (CIA).

Macrophage colony-stimulating factor (M-CSF) is a key factor for osteoclastogenesis at the bone-pannus interface in patients with rheumatoid arthritis as well as a receptor activator of NF-kappaB ligand (RANKL). Imatinib mesylate inhibits the phosphorylation of c-fms, a receptor for M-CSF. The present study investigates the effect of imatinib mesylate on joint destruction in rats with collagen-induced arthritis (CIA) and on osteoclastogenesis in vitro. Imatinib mesylate (50 or 150 mg/kg), dexamethasone, or vehicle was administered daily to CIA rats for 4 weeks from the onset of arthritis. Hind-paw swelling and body weight were measured weekly. At weeks 2 and 4, the metatarsophalangeal (MTP) joints and the ankle and subtalar joints were radiographically and histologically assessed. The effect of imatinib mesylate on osteoclast formation from rat bone marrow cells with M-CSF and soluble RANKL (sRANKL) in vitro was also examined. Radiographic assessment showed that 150 mg/kg imatinib mesylate suppressed the destruction of the MTP and the ankle and subtalar joints at week 2, and MTP joint destruction at week 4 in CIA rats, although hind-paw swelling was not suppressed. The number of TRAP-positive cells at the bone-pannus interface was significantly reduced in the group administered with 150 mg/kg imatinib mesylate compared with that given vehicle at week 4. Imatinib mesylate dose-dependently inhibited the proliferation of M-CSF-dependent osteoclast precursor cells in vitro as well as osteoclast formation induced by M-CSF and sRANKL. These findings suggest that imatinib mesylate could prevent joint destruction in patients with rheumatoid arthritis.