leptin and Femoral-Fractures

The combination of traumatic brain injury (TBI) and long-bone fracture leads to increased formation of callus and mineral density in wild-type (WT) mice. However, this effect was not detected radiologically in leptin-deficient mice. Due to the complex interactions between hormonal and bone metabolism and the important role of leptin in this setting, our aim was to investigate morphologic properties and the tissue composition in the fracture callus comparing WT and leptin-deficient mice.. Female C57/Black6N mice (n=36) and leptin deficient ob/ob mice (n=36) each were assigned to two groups (fracture Fx/combined trauma Fx/TBI). Femoral osteotomy was stabilized with external fixator, TBI was induced with controlled cortical impact injury. After sacrifice of the animals, femora were harvested, cryofixated, and 7 µm slices were prepared. Staining was performed adhering to Movat's Pentachrome protocol. Histomorphometric analysis, quantifying percentage of mineralized bone area, and a semi-quantitative evaluation of bone bridging were performed.. Leptin deficient mice showed a higher rate of non-union after osteotomy, less callus formation in the osteotomy gap, and unexpected bone and cartilage formation independent of the osteotomy region.. Leptin plays an important role in fracture healing and bone formation. Without Leptin, the positive effect of TBI on fracture healing ceases. The comprehension of the underlying pathophysiological process could sign important for novel strategies in stimulation of fracture healing.

Topics: Animals; Brain Injuries, Traumatic; Disease Models, Animal; Female; Femoral Fractures; Femur; Fracture Healing; Leptin; Mice; Osteogenesis; Osteotomy

Leptin's role in bone formation has been reported, however, its mechanism of affecting bone metabolism is remaining unclear. In this study, we aimed to test whether leptin has a positive effect on fracture healing through the possible mechanism of increasing vascular endothelial growth factor (VEGF) expression in callus tissue.. Standardized femur fractures were created in leptin-deficient ob/ob and wildtype C57BL/6J mice, and recombinant mouse leptin or its vehicle (physiological saline) was administered intraperitoneally during the study. Body weight, radiological, histologic and immunoblotting analyses were performed at different stages of fracture healing.. The results showed that leptin treatment led to lower rate of body weight change in both mice genotypes. Radiological and histological analyses showed that the experimental groups had better fracture healing at 14, 21 and 28 days compared to the control groups. Leptin-treated groups had significantly higher VEGF expression in callus compared with the control groups at 2 and 3 weeks post-fracture except normal mice at 2 weeks, and leptin-deficient mice had higher VEGF levels in calluses than normal mice at the same timepoint.. Low-dose systemically-administered leptin has a positive effect on promoting fracture healing during the latter stages in a clinically-relevant mouse bone fracture model, and increase callus VEGF levels.

Topics: Animals; Bony Callus; Disease Models, Animal; Femoral Fractures; Fracture Healing; Injections, Intraperitoneal; Leptin; Male; Mice; Mice, Inbred C57BL; Mice, Obese; RNA, Messenger; Tomography, X-Ray Computed; Vascular Endothelial Growth Factor A

Patients with traumatic brain injury (TBI) and long-bone fractures can show increased callus formation. This effect has already been reproduced in wild-type (wt) mice. However, the mechanisms remain poorly understood. Leptin is significantly increased following TBI, while its role in bone healing remains unclear. The aim of this study was to evaluate fracture healing in leptin-deficient ob/ob mice and to measure any possible impact of TBI on callus formation. 138 female, 12 weeks old, ob/ob mice were divided into four groups: Control, fracture, TBI and combined trauma. Osteotomies were stabilized with an external fixator; TBI was induced with Controlled Cortical Impact Injury. Callus bridging was weekly evaluated with in vivo micro-CT. Biomechanical testing was performed ex vivo. Micro-CT showed high non-union rates after three and four weeks in the fracture and combined trauma group. No differences were observed in callus volume, density and biomechanical properties at any time point. This study shows that bony bridging is impaired in the present leptin-deficient trauma model. Furthermore, the phenomenon of increased callus formation after TBI could not be reproduced in ob/ob mice, as in wt mice. Our findings suggest that the increased callus formation after TBI may be dependent on leptin signaling.

Topics: Animals; Bony Callus; Brain Injuries, Traumatic; Female; Femoral Fractures; Fracture Healing; Leptin; Mice; Mice, Obese; Random Allocation

BACKGROUND Leptin plays a crucial role in bone metabolism, and its level is related to bone callus formation in the fracture repair process. The objective of this study was to evaluate the effect of recombinant leptin on the healing process of femoral fractures in rats. MATERIAL AND METHODS Forty-eight male Sprague Dawley (SD) rats with an average body weight of 389 g (range: 376-398 g) and an average age of 10 weeks were included in this animal research, and all rats were randomly divided into two major groups. Then standardized femur fracture models were implemented in all SD rats. Rats in the control group were treated with only 0.5 mL of physiological saline, and rats in the experimental group were treated with recombinant leptin 5 μg/kg/d along with the same 0.5 mL of physiological saline for 42 days intraperitoneally. At the same time, each major group was evenly divided into three parallel subgroups for each parallel bone evaluation separately at the second, fourth, and sixth weeks. Each subgroup included eight rats. RESULTS The total radiological evaluation results showed that the healing progress of femoral fracture in the experimental group was superior to that in the control group from the fourth week. At the sixth week, experimental group rats began to present significantly better femoral fracture healing progress than that of the control group rats. Results of biomechanics show the ultimate load (N) and deflection ultimate load (mm) of the experimental group rats was significantly increased compared with that of the control group rats from the fourth week. CONCLUSIONS Our results suggest that leptin may have a positive effect on SD rat femur fracture healing.

Topics: Animals; Disease Models, Animal; Femoral Fractures; Fracture Healing; Leptin; Male; Random Allocation; Rats; Rats, Sprague-Dawley; Recombinant Proteins

To evaluate the effect of leptin combined with CoCl2 on rat femur fracture healing. 48 male Sprague Dawley rats were randomly divided into two main groups. Then standardized femur fractures were created to all rats. Control group rats were treated with 0.5 mL physiological saline, and experimental group rats were treated with 5 μg/Kg.d leptin and 15 mg/Kg.d CoCl2 along with 0.5 mL physiological saline for 42 days intraperitoneally. Each main group was divided into three subgroups for each evaluation at second, fourth and sixth weeks, each subgroup included eight rats. The radiological evaluation showed that the fracture healing progress of experimental group was superior to control group from second week. At fourth week, experimental group had better fracture healing progress than control group significantly. Results of biomechanics show the ultimate load (N) and deflection ultimate load (mm) of experimental group was significantly increased than that in control group from fourth week. The present result demonstrated that leptin combined with CoCl2 significantly increased the mRNA expression levels of HIF1A, Vegfa, Runx2, Bmp2, Bglap and Alpl. It suggested that leptin combined with CoCl2 have a positive effect on rat femur fracture healing by activating the HIF1A pathway.

Topics: Animals; Cobalt; Core Binding Factor Alpha 1 Subunit; Disease Models, Animal; Drug Therapy, Combination; Femoral Fractures; Fracture Healing; Hypoxia-Inducible Factor 1, alpha Subunit; Injections, Intraperitoneal; Leptin; Male; Random Allocation; Rats; Rats, Sprague-Dawley; Treatment Outcome; Up-Regulation; Vascular Endothelial Growth Factor A

Previously reported fracture rates in patients with spinal cord injury range from 1% to 20%. However, the exact role of spinal cord injury in bone metabolism has not yet been clarified. In order to investigate the effects of serum leptin and bone mineral density on the healing of long bone fractures in men with spinal cord injury, 15 male SCI patients and 15 matched controls were involved in our study. The outcome indicated that at 4 and 8 weeks after bone fracture, callus production in patients with spinal cord injury was lower than that in controls. Besides, bone mineral density was significantly reduced at 2, 4 and 8 weeks. In addition, it was found that at each time point, patients with spinal cord injury had significantly higher serum leptin levels than controls and no association was found between serum leptin level and bone mineral density of lumbar vertebrae. Moreover, bone mineral density was positively correlated with bone formation in both of the groups. These findings suggest that in early phases i.e. week 4 and 8, fracture healing was impaired in patients with spinal cord injury and that various factors participated in the complicated healing process, such as hormonal and mechanical factors.

Topics: Adult; Biomarkers; Bone Density; Femoral Fractures; Fracture Healing; Fractures, Bone; Humans; Leptin; Male; Middle Aged; Spinal Cord Injuries; Spine; Tibial Fractures; Young Adult

Obesity is considered a clinical risk sign for Legg-Calvé-Perthes disease (LCPD). Leptin is primarily secreted by adipocytes, and it regulates adipose tissue mass and body weight. Furthermore, obesity is clearly associated with increased leptin levels. We investigated the roles of leptin and the soluble leptin receptor (sOB-R) in LCPD. This matched case-control study included 38 male and 3 female patients with LCPD, and an equal number of age-(range was 4-12) and sex-matched control patients with healthy fractures. Serum leptin and sOB-R levels were quantified with ELISA. The free leptin index (FLI) was defined as the ratio of leptin to sOB-R levels. Serum leptin levels, sOB-R, and FLI were compared between groups. The relationship between leptin, disease severity, and treatment outcomes were analyzed in the LCPD group. There were no significant differences between groups in terms of age, sex, and body mass index (BMI) percentile. Mean leptin levels (p = 0.042), sOB-R levels (p = 0.003), and FLI (p = 0.013) differed significantly between groups. In the LCPD group, the serum leptin levels, sOB-R levels, and FLI differed significantly between the lateral pillar and Stulberg classification groups (p < 0.05). Also, the leptin levels and FLI increased significantly according to the lateral pillar and Stulberg classifications even after adjusting for age and BMI percentile (p < 0.05). Circulating leptin and FLI were significantly higher in the LCPD group. Furthermore, leptin, disease severity, and treatment outcomes were associated. This correlation suggests that leptin might play an important role in LCPD pathogenesis.

Topics: Body Mass Index; Case-Control Studies; Child; Female; Femoral Fractures; Femur Head Necrosis; Humans; Legg-Calve-Perthes Disease; Leptin; Male; Obesity; Radiography; Receptors, Leptin; Risk Factors; Solubility

We hypothesized that leptin is expressed in a specific time sequence during fracture healing, and its deficiency leads to impaired healing.. Control (C57BL/6) mice and leptin -/- obese (ob/ob) mice were used. ARM 1:: Fracture callus was harvested at 1, 3, 5, 7, 10, 14, and 21 days (n = 8/time point) after closed middiaphyseal femur fractures were created in 56 C57BL/6 mice, and reverse transcriptase polymerase chain reaction analysis was then performed. Levels of leptin were tracked at each time point listed. ARM 2:: Forty-two C57BL/6 controls and 42 ob/ob mice underwent open stabilized middiaphyseal femur fractures, and tissues were harvested at 14, 21, and 42 days and radiographic, histologic, and quantitative computerized tomography analyses were performed. ARM 3:: Murine recombinant leptin was applied directly at the newly created fracture site in 2 separate groups (10 or 100 μg of leptin) of 42 ob/ob mice. Two-factor analysis of variance and the Student t-test were used for statistical analysis.. The time course of Leptin mRNA expression within a fracture callus was detected. Delay in callus maturation was demonstrated radiographically and histologically in the ob/ob mice. ob/ob fractures had an increase in total callus volume by quantitative computerized tomography (P < 0.05). Application of local leptin at both doses reversed the delay in healing.. Leptin is expressed in a unique time course during fracture healing and leptin deficiency leads to impaired fracture healing that reverses by local application of leptin.

Topics: Animals; Bony Callus; Disease Models, Animal; Female; Femoral Fractures; Fracture Healing; Leptin; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Obese; Obesity; Recombinant Proteins; RNA, Messenger; Time Factors; Tomography, X-Ray Computed; Treatment Outcome

To observe serum and callus leptin expression within the setting of fracture and traumatic brain injury (TBI).. A total of 64 male SD rats were randomized equally into 4 groups: nonoperated group, TBI group, fracture group, and fracture+TBI group. Rats were sacrificed at 2, 4, 8 and 12 weeks after fracture+TBI. Serum leptin was detected using radioimmunoassay, and callus formation was measured radiologically. Callus leptin was analyzed by immunohistochemistry.. Serum leptin levels in the fracture group, TBI group and combined fracture+TBI group were all significantly increased compared with control group at the 2 week time-point (P less than 0.05). Serum leptin in the combined fracture +TBI group was significantly higher than that in the fracture and TBI groups at 4 and 8 weeks after injury (P less than 0.05). The percentage of leptin-positive cells in the fracture+TBI callus and callus volume were significantly higher than those in the fracture-only group (P less than 0.01).. We demonstrated elevated leptin expression within healing bone especially in the first 8 weeks in a rat model of fracture and TBI. A close association exists between leptin levels and the degree of callus formation in fractures.

Topics: Animals; Brain Injuries; Femoral Fractures; Fracture Healing; Immunohistochemistry; Leptin; Male; Osteogenesis; Rats; Rats, Sprague-Dawley

Few studies have reported a relationship between leptin induced by spinal cord injury (SCI) and healing bone tissue.. To observe serum and callus leptin expression within the setting of fracture and traumatic SCI.. Seventy-two male Sprague Dawley rats were randomized equally into four groups: control, SCI group, fracture group, and fracture/SCI group. Rats were sacrificed at 7, 14, 21, and 28 days post-fracture/SCI. Serum leptin was detected using radioimmunoassay at 1, 7, 14, 21, and 28 days, and callus formation was measured radiologically at 14, 21, and 28 days. Callus leptin was analyzed by means of immunohistochemistry.. Serum leptin in the fracture group, SCI group, and combined fracture/SCI group were all significantly increased compared to control group at the 1, 7, 14, and 2-day time points (P < 0.05). Serum leptin in the combined fracture/SCI group was significantly higher than in the fracture group at 7, 14, and 21 days (P < 0.05), and higher than in SCI groups at 14 and 21days after operation (P < 0.05). The percentage of leptin-positive cells in the fracture/SCI callus, and callus volume was significantly higher than in the fracture-only group (P < 0.001).. Overall, elevated leptin expression was demonstrated within healing bone especially in the 21 days of a rat model combining fracture and SCI. A close association exists between leptin levels and the degree of callus formation in fractures.

Topics: Animals; Disease Models, Animal; Femoral Fractures; Leptin; Male; Microscopy, Electron, Transmission; Muscle, Skeletal; Radioimmunoassay; Random Allocation; Rats; Rats, Sprague-Dawley; Spinal Cord; Spinal Cord Injuries; Statistics as Topic; Time Factors