Yutaka Miyanaga

Collagen hybridization with poly(l-lactic acid) braid promotes ligament cell migration

Abstract The purpose of this study is to evaluate the cellular response to a poly( l -lactic acid) (PLLA)-collagen hybrid scaffold for ligament regeneration based on tissue engineering. A three-dimensional (four-axis) braid with a diameter of 2.5 mm was made from PLLA filaments. The braid was further hybridized with bovine type I collagen to prepare the PLLA-collagen hybrid braid. Cellular responses of ligament cells to the PLLA and PLLA-collagen hybrid braids were evaluated both in vitro and in vivo. More cells and more homogeneous cell distribution were observed in vitro in the hybrid braid than in the PLLA braid. More fibroblast immigration and neo-angiogenesis were detected in the hybrid braid than in the PLLA braid when implanted on ruptured medial collateral ligament (MCL). Hybridization with collagen facilitated cell seeding and spatial cell distribution, and promoted cell immigration and neo-angiogenesis. The hybrid braid would be useful for ligament tissue engineering.

Effects of different exposures of hyperbaric oxygen on ligament healing in rats

Hyperbaric oxygen (HBO) is a method of augmenting, intermittently, oxygen availability to tissues. We examined the effect of three different HBO exposures on the healing of experimentally induced ligament lacerations in the right hind limb of 44 male Wistar rats. Animals were divided into four groups after ligament injury: (a) control group, animals breathed room air at 1 ATA (atmosphere absolute) in a hyperbaric chamber for 60 min; (b) HBO treatment at 1.5 ATA for 30 min once a day, (c) HBO treatment at 2 ATA for 30 min once a day, (d) 2 ATA for 60 min once a day. At 14 days post‐ligament injury, we compared the ligaments of the four treatment groups for gross appearance, histology and expression of pro‐α(I) mRNA by northern hybridization. Our results indicate that HBO was effective in promoting ligament healing compared to control (p < 0.01). Of these three exposures, HBO at 2 ATA for 60 min was the most effective, resulting in enhanced extra‐cellular matrix deposition as measured by collagen synthesis.

Hyperbaric Oxygen as an Adjuvant for Athletes

AbstractThere has recently been a resurgence in interest in hyperbaric oxygen (HBO) treatment in sports therapy, especially in Japan. Oxygen naturally plays a crucial role in recovery from injury and physiological fatigue. By performing HBO treatment, more oxygen is dissolved in the plasma of the pulmonary vein via the alveolar, increasing the oxygen reaching the peripheral tissues. HBO treatment is therefore expected to improve recovery from injury and fatigue.HBO treatment has been reported to reduce post-injury swelling in animals, and in humans; swelling was also mitigated, but to a lesser extent. Positive results have also been reported regarding tissue remodelling after injury, with injuries involving bones, muscles and ligaments showing improved recovery. Furthermore, HBO treatment has effectively increased recovery from fatigue. This was clearly seen at the Nagano Winter Olympics, where sports players experiencing fatigue were successfully treated, enabling the players to continue performing in the games.Despite its potential, HBO treatment does have its risks. Increasing oxygen levels in tissues poses a risk to DNA through oxidative damage, which can lead to pathological changes in the CNS and the lungs. Regarding the operating of HBO systems, safer administration should be advised.Further research into HBO treatment is required if this therapy is to become more widespread. It should become possible to tailor treatment to an individual’s condition in order to use HBO treatment efficiently.

Differences in EMG Activity in Scapular Plane Abduction under Variable Arm Positions and Loading Conditions

PURPOSE The present study was performed to investigate the activities of four shoulder muscles-the supraspinatus, the middle deltoid, the infraspinatus, and the upper trapezius-in scapular plane abduction in various exercise conditions. METHODS Eight male subjects (mean +/- SD: 23.4 +/- 1.3 yr) with an asymptomatic nondominant left shoulder participated in this study. Each subject performed scapular plane abduction with humeral external rotation (full can position) and with humeral internal rotation (empty can position), producing constant target torques of 4 and 12 N.m, respectively. In addition, the subjects performed each exercise in the supine position with the limb supported by straps. Electromyogram (EMG) was recorded with intramuscular electrodes at the supraspinatus and infraspinatus, and with surface electrodes placed at the middle deltoid and upper trapezius. The EMG activity (RMS) of each muscle was normalized according to the highest EMG activity (100% MVC) during a maximum manual muscle test for the corresponding muscle (% MVC). RESULTS EMG activity of the supraspinatus was significantly greater than those of the other shoulder muscles in the full can position from 10-20 degrees to 50-60 degrees arcs with a target torque of 4 N.m (P < 0.05). In contrast, the supraspinatus and middle deltoid showed similar EMG activities under other exercise conditions. CONCLUSIONS These results suggest that there is an exercise condition that induces greater activity of the supraspinatus in scapular plane abduction.

Mechanical stretch in anterior cruciate ligament derived cells regulates type I collagen and decorin expression through extracellular signal-regulated kinase 1/2 pathway

Abstract Anterior cruciate ligament (ACL) is continuously exposed to tensile load, which is generally recognized to be an essential factor in maintaining the physiological homeostasis of the ACL fibers during daily activities. Although this kind of mechanical stimulation is clearly known to play an important role in quickening repair of ACL injury, responses of ACL cells to mechanical stimulation still remain unclear. We have investigated whether extracellular signal-regulated kinase 1/2 (ERK1/2) in human ruptured ACL-derived cells are phosphorylated and involved in type I collagen (Col I) and decorin gene expression by mechanical stimulation. Mechanical stretch stimulates time-dependent phosphorylation of ERK1/2 in human ruptured ACL-derived cells. While Col I gene expression levels were increased in 48-h continuous mechanical stretch, decorin gene expression levels were decreased for 24-h continuous stimulation. Decorin gene expression levels were increased, however, in mechanical stretch+PD98059, which is an inhibitor of ERK pathway, treated cells as compared with control cells at 24 h. Our results show that ERK pathway is stimulated by mechanical stretch, and may be involved in regulation of Col I and decorin gene expression in ACL-derived cells.

A new socket design for the dysplastic acetabulum in total hip replacement.

A special socket was designed by holography for total hip replacement for the treatment of the dysplastic acetabulum and correction of the deformation pattern. Excellent clinical results of 12 cases demonstrate that the special socket design provides good stability as well as favorable redistribution of mechanical forces about the hip joint.

Effects of transcutaneous topical injection of oxygen on vascular endothelial growth factor gene into the healing ligament in rats

The effects of intermittent exposure to oxygen injection on an experimentally induced ligament tear were studied in the right hind limb of 17 male Sprague–Dawley rats. Two rats were used for monitoring the partial oxygen pressure (pO2) of subcutaneous tissue and 15 rats were divided into the following three groups of 5 after an experimentally induced ligament tear: Group A, control group; Group B, injection of 0.5 ml hyaluronan to the wound transcutaneously; Group C, injection of 0.5 ml hyaluronan mixed with haemoglobin and oxygen (n = 5). At 7 days post‐ligament injury, we compared the ligaments of the three treatment groups for gross appearance, histology and expression of vascular endothelial growth factor (VEGF) mRNA by RT‐PCR. Our results indicate that the pO2 was immediately elevated to 334.6 mmHg by topical oxygen injection and this method was effective in promoting vessel formation in comparison to the control group (p < 0.01). However, the expression of VEGF mRNA in the topical oxygen injection group (Group C) was lower than that in control group (p < 0.05). Our results suggest that oxygen is able to accelerate vessel formation in spite of its effect of decreasing VEGF mRNA. Our method of using topical injection proved to be useful in healing the ligament and the wound.

Calcium Phosphate Hybridized with Human Semitendinosus and Gracilis Tendon Grafts

We hybridized calcium phosphate (CaP) with human semitendinosus and gracilis (ST/G) tendon grafts using an alternate soaking process. To evaluate quantitatively and histologically assess the CaP hybridized human ST/G tendon grafts, we classified them into three groups according to their soaking time – number of soaking cycle: 30 sec – 20 cycles (Group A), 1 min – 15 cycles (Group B), 3 min – 5 cycles (Group C). The tendon grafts were divided into three parts: tibial end (TE), femoral end (FE) and intra-articular (IA) portion. TE was secured using the Krackow technique with No. 2 nonabsorbable sutures, and an Endobutton-CL (Smith & Nephew, USA) was passed through the looped FE, as performed clinically. Then, the IA portion was covered with the sleeve of a rubber glove to prevent CaP hybridization. More soaking cycles induced greater deposition of CaP in the tendon grafts when the total soaking time was the same. Covering the IA portion with a rubber sleeve prevented of CaP deposition. A large amount of CaP in TE was deposited because suture holes increased the total contact area with the solutions.

Dynamic viscoelasticity of the healing ligament treated by in vivo intermittent oxygen exposure in rats

Abstract The effects of intermittent exposure to hyperbaric oxygen (HBO) on experimentally induced ligament tear were studied in the right hind limb of 10 male Wistar rats. Ten rats were divided into the following two groups of five: Group A, merely exposed to normobaric room air (control group); Group B, treated with HBO at 2 ATA 100% O2×60 min×once/day (HBO group). The dynamic stiffness and tanδ of the injured patellar ligament were measured 4 weeks after infliction with the original viscoelastic spectrometer. From our results, the stiffness of injured ligament did not recover from the average of control site at 4 weeks after injury, whether or not HBO was used (p This study suggests, from the point of elasticity, that the ligament of accelerated collagen synthesis with HBO were still fragile at the time of 4 weeks after wounding. However, dynamic viscoelasticity was found to be not influenced enough by in vivo intermittent oxygen supply.

Effect of exercise on mechanical properties and density of bone

Effects of swimming and running trainings on mechanical properties of bone and bone density were investigated. Mechanical tests were conducted for tibial bone. The dynamic stiffness and tan δ were measured by a viscoelastic spectrometer. The three‐point bending test was performed with an Instron‐type universal testing machine. Bone mineral content was measured by photon absorptimetry at the middle site of the tibial bone. In the swimming case the stiffness and tan δ were, in average, larger for the trained rats than for the controlled group. The strength and the bone density were also larger for the trained group. In the running case, the negative effects were observed on these variables.