Repair of segmental bone defects in rabbit tibia promoted by a complex of β-tricalcium phosphate and hepatocyte growth factor

Background: Segmental bone defect repair remains a clinical and scientific challenge with increasing interest focused on bone tissue engineering. Clinical studies are ongoing to address application of hepatocyte growth factor (HGF) for treatment of some diseases; however, the use of HGF in bone tissue engineering has not been addressed. This study was performed to evaluate the effect of HGF in a complex of β-tricalcium phosphate (β-TCP) and collagen in repairing segmental bone defects. Methods: Segmental bone defects 5 mm long were created in the middle of the tibial shafts of rabbits. The defect was stabilized with external fixators and implanted with a complex of β-TCP granules and collagen, with or without 100 μg recombinant human HGF. Biweekly, bone regeneration and β-TCP resorption were assessed radiographically and histologically. At 4 and 8 weeks, bone regeneration was evaluated by use of micro-computed tomography and mechanical tests. Results: Compared with the bone tissue treated with β-TCP and collagen, mineralization, angiogenesis, new bone formation, and absorption of β-TCP were promoted 4 weeks postoperatively by treatment with HGF in the β-TCP and collagen group. These changes were associated with promoting biomechanical regeneration. By 8 weeks, the formation of bone marrow in newly generated bone and absorption of the β-TCP granules were completed in a shorter period by combining HGF with β-TCP and collagen, compared with tissues without HGF. Conclusions: The combined application of HGF in a β-TCP and collagen matrix promoted histological bone healing and augmented mechanical strength of the healing bone, particularly in the early stages. The combined use of HGF and β-TCP for treatment of bone defects made a substantial difference. © 2012 The Japanese Orthopaedic Association.金沢大学博士学位論文 五嶋謙一, Theisis of GOSHIMA, Kenich

Promotion of rabbit ligament healing by local delivery of hepatocyte growth factor

Background: Extracapsular ligament injuries of the knee and ankle are common injuries. Ligaments heal slowly, usually over months or longer by scar formation rather than by tissue regeneration. This study was performed to evaluate the therapeutic effect of locally delivered recombinant hepatocyte growth factor (HGF) on the early healing of ligaments in a rabbit model. Methods: Japanese white rabbits were subjected to a standardized gap injury in the medial collateral ligaments (MCLs) of both knees. Each rabbit underwent bilateral transection of the midsubstance of the MCL, which was not repaired. During postoperative days 0-6, the rabbits were injected with 10 μg human recombinant HGF into the right MCL, while the left MCL was injected with saline alone. One, 3, 6, and 12 weeks after surgery, experimental rabbits were sacrificed. The structural properties of the femur-MCL-tibia complex were then assessed and the tissue was subjected to histological evaluation. To see the distribution of cells that express c-Met receptor, the tissue was subjected to immunohistochemistry. Results: Immunohistochemical evaluation revealed that c-Met expression was observed particularly at opposing ligament ends in the HGF-treated limbs 1 week after surgery. Histological evaluation revealed earlier neovascularization and more aligned collagen fibers in the MCLs of the HGF-treated group than the control group. In mechanical evaluations, similar ligament failure modes were noted in the two groups. After 3 weeks, HGF-treated limbs had significantly improved structural properties than the paired control limbs. Conclusions: Our findings indicate local administration of recombinant HGF promotes early steps in ligament healing and the repair of structural properties in a rabbit model. Local administration of HGF may represent a new therapeutic approach to accelerating healing and rehabilitation after ligament injury. © 2011 The Japanese Orthopaedic Association

Precise risk factors for Osgood–Schlatter disease

Introduction: A number of studies have examined the risk factors for Osgood–Schlatter disease (OSD). Studies on risk factors have not necessarily accurately demonstrated the risk factors of this disease because they were not prospective cohort studies or the populations in the studies were not categorized by the skeletal maturation of the tibial tuberosity. We can identify the precise risk factors for OSD by performing a prospective cohort study of a group of asymptomatic patients in particular times of adolescent using ultrasonography. In the present study, we aimed to investigate the precise risk factors for OSD. Methods: For all examinations, we used a 3-stage classification for tibial tuberosity development observed on ultrasonography: sonolucent (stage S), individual (stage I), and connective stages (stage C). Among 150 players with 300 knees, we included 37 male players with 70 knees at asymptomatic stage I on the first examination. We re-examined the included knees 1 year after the first examination and compared 10 knees with OSD (OSD group) and 60 knees without OSD (control group). Height, body weight, body mass index, tightness of the quadriceps femoris and hamstring muscles, muscle strength during knee extension, and flexion were assessed during the first medical examination. Results: The incidence of OSD was 14.3 % in this 1-year cohort study. A significant difference was found in body weight, quadriceps muscle tightness, and muscle tightness and strength during knee extension between the 2 groups. The precise risk factors for OSD were increased, namely the quadriceps femoris muscle tightness and strength during knee extension and flexibility of the hamstring muscles, using logistic regression analysis. Conclusions: This information may be useful for teaching quadriceps stretching in preadolescent male football players with stage I. © 2015 Springer-Verlag Berlin Heidelber

Relationship between the skeletal maturation of the distal attachment of the patellar tendon and physical features in preadolescent male football players

Purpose: The aim of this study was to compare ultrasonography stages of the tibial tuberosity development and physical features. Methods: This study examined 200 knees in 100 male football players aged 10-15 years. Tibial tuberosity development on ultrasonography was divided into 3 stages: Sonolucent stage (stage S), Individual stage (stage I), and Connective stage (stage C). Age, height, quadriceps and hamstring muscle tightness, and muscle strength in knee extension and flexion were determined. These findings were compared with the respective stages of development. Results: The tibial tuberosity was stage S in 27 knees, stage I in 69 knees, and stage C in 104 knees, with right and left sides at the same stage in 95 %. Average age and height significantly increased with advancing tibial tuberosity development. Quadriceps tightness increased with tibial tuberosity development. Hamstring tightness decreased with development. The strength of both knee extension and flexion increased with advancing development, with a greater change seen in knee extension, hamstring/quadriceps ratio: stage C, 0.74; stage A, 0.64; stage E, 0.53. Conclusions: Osgood-Schlatter pathogenesis reportedly involves increased quadriceps tightness with rapidly increasing femoral length during tibial tuberosity development. In this study, it was confirmed that quadriceps tightness increased, yet hamstring tightness decreased, suggesting that quadriceps tightness is not due to femoral length alone. Other factors, including muscle strength, may be involved. The study shows that thigh muscle tightness and thigh muscle performance change with the skeletal maturation of the distal attachment of the patellar tendon. These results add new information to the pathogenesis of Osgood-Schlatter disease. Level of evidence: Cross-sectional study, Level III. © 2012 Springer-Verlag Berlin Heidelberg

Comparison of Targeted vs Random Biopsies for Surveillance of Ulcerative Colitis-Associated Colorectal Cancer

Background & AimsA random biopsy is recommended for surveillance of ulcerative colitis (UC)-associated colorectal cancer. However, a targeted biopsy might be more effective. We conducted a randomized controlled trial to compare rates of neoplasia detection by targeted vs random biopsies in patients with UC.MethodsWe performed a study of 246 patients with UC for 7 years or more, seen at 52 institutions in Japan from October 1, 2008 through December 31, 2010. Patients were randomly assigned to the random group (4 random biopsies collected every 10 cm in addition to targeted biopsies, n = 122) or the target group (biopsies collected from locations of suspected neoplasia, n = 124). The primary end point was the number of neoplastic lesions detected in a single surveillance colonoscopy. We estimated the ratio and difference in the mean number of neoplastic lesions between the groups. We also evaluated the non-inferiority between the groups as an exploratory study. A non-inferiority margin of 0.65 (0.13 of 0.20) was considered for the ratio of the mean number of neoplastic lesions between groups.ResultsThe mean number of biopsies found to contain neoplastic tissue per colonoscopy was 0.211 (24 of 114) in the target group and 0.168 (18 of 107) in the random group (ratio of 1.251; 95% confidence interval, 0.679–2.306). The lower limit was above the non-inferiority margin of 0.65. Neoplasias were detected in 11.4% of patients in the target group and 9.3% of patients in the random group (P = .617). Larger numbers of biopsy samples per colonoscopy were collected in the random group (34.8 vs 3.1 in the target group; P < .001), and the total examination time was longer (41.7 vs 26.6 minutes in the target group; P < .001). In the random group, all neoplastic tissues found in random biopsies were collected from areas of the mucosa with a history or presence of inflammation.ConclusionsIn a randomized controlled trial, we found that targeted and random biopsies detect similar proportions of neoplasias. However, a targeted biopsy appears to be a more cost-effective method. Random biopsies from areas without any signs of present or past inflammation were not found to contain neoplastic tissues. Clinical Trial Registry: UMIN000001608

Familial predisposition to anterior cruciate ligament injury

Although several risk factors for anterior cruciate ligament (ACL) injury have been evaluated in the literature, there are few reports on familial predisposition. This study investigated the familial predisposition to ACL injury. The study included 350 patients who underwent ACL reconstruction between January 2005 and September 2008. All patients were surveyed by telephone or a written questionnaire about family history (FH) of ACL injury, sports played by family members, and mechanisms of injury. We also compared age, sex, height, weight, body mass index, Tegner activity score, general joint laxity, and tibial slope between an FH group (with FH) and a control group (without FH). In addition, we compared the incidence of ACL graft rupture and contralateral ACL rupture 2 years after primary surgery. Complete information was obtained from 316 patients, 38 (12.0%) of whom had FH of ACL injury. Two families had three members with ACL injuries. Of the 40 family members with ACL injuries, 38 (95%) had noncontact injuries and 34 (85%) shared a similar mechanism of injury with the related patient. No significant differences were identified between the two groups, except that tibial slope was significantly greater in the FH group than in the control group. Although the incidence of repeat ACL injury was greater in the FH group (23.7%) than in the control group (16.4%), there was no significant difference. Our results indicated a high probability of familial predisposition to many of the identified risk factors for ACL injury. In addition, patients with FH of ACL injury might be at high risk for initial and repeat ACL injuries. Therefore, prevention programs should be implemented for patients with FH of ACL injury in order to decrease the risk of these injuries

Key Process and Factors Controlling the Direct Translocation of Cell-Penetrating Peptide through Bio-Membrane

Cell-penetrating peptide (CPP) can directly penetrate the cytosol (cytolysis) and is expected to be a potent vector for a drug delivery system (DDS). Although there is general agreement that CPP cytolysis is related to dynamic membrane deformation, a distinctive process has yet to be established. Here, we report the key process and factors controlling CPP cytolysis. To elucidate the task, we have introduced trypsin digestion of adsorbed CPP onto giant unilamellar vesicle (GUV) to quantify the adsorption and internalization (cytolysis) separately. Also, the time-course analysis was introduced for the geometric calculation of adsorption and internalization amount per lipid molecule consisting of GUV. As a result, we found that adsorption and internalization assumed to occur successively by CPP molecule come into contact with membrane lipid. Adsorption is quick to saturate within 10 min, while cytolysis of each CPP on the membrane follows successively. After adsorption is saturated, cytolysis proceeds further linearly by time with a different rate constant that is dependent on the osmotic pressure. We also found that temperature and lipid composition influence cytolysis by modulating lipid mobility. The electrolyte in the outer media is also affected as a chemical mediator to control CPP cytolysis by following the Hoffmeister effect for membrane hydration. These results confirmed the mechanism of cytolysis as temporal and local phase transfer of membrane lipid from L&alpha; to Mesh1, which has punctured bilayer morphologies