Fracture Healing In Ovariectomized Rats Research Articles

Autologous ADSCs with exogenous NPY promotes fracture healing in ovariectomized rats

ObjectiveTo evaluate the role of autologous adipose-derived stem cells (ADSCs) with exogenous neuropeptide Y (NPY) on osteoporotic fracture healing. MethodsWe established a fracture healing model in ovariectomized rats of osteoporosis. Autologous ADSCs, isolated from rats' subcutaneous adipose tissue, with exogenous NPY were transplanted into the fracture site four times a week. The fracture healing was observiked with X-ray diagnostic techniques, and the rats’ tibias were taken out for section-staining and micro-CT scanning 3 and 6 weeks after fracture. Next, we explored the underlying mechanism by which the transplantation contributed to fracture healing. ResultsCo-culture and co-transplantation of ADSCs with NPY could stimulate the osteoporotic fracture healing. NPY may promote the osteogenic differentiation of ADSCs through Y1 receptor. ConclusionThis result provides a platform for the development of novel therapies for bone regeneration with endogenous ADSCs.

The effects of romosozumab combined with active vitamin D3 on fracture healing in ovariectomized rats

BackgroundIn this study, we investigated the potential acceleration of fracture healing and bone mineral density-increasing effects of romosozumab and active vitamin D3 combination therapy for fractures in ovariectomized rats.MethodsOvariectomy was performed on 40 24-week-old female Sprague–Dawley rats. After 8 weeks, the rats were subjected to periosteum removal and osteotomy of the femoral shaft followed by osteosynthesis with intramedullary nailing to create fracture models. The rats were then divided into four groups: C group (control), R group (receiving romosozumab at 25 mg/kg once a month via subcutaneous injection), VD group (receiving active vitamin D3 at 0.2 µg/kg twice a week via subcutaneous injection), and R + VD group. Further, 10 rats were included in a sham group. At 10 weeks after the intervention, both femurs were removed and blood samples were collected from all rats. Soft X-ray imaging was used to evaluate bone union, and microcomputed tomography (micro-CT) was used for bone morphometric evaluation. Toluidine blue staining was used for the histopathological evaluation of the undecalcified specimens, and bone turnover marker levels were measured using enzyme-linked immunosorbent assay.ResultsBone morphometry analysis via micro-CT revealed increased mineral density of the trabecular bone in the R + VD group femurs, demonstrating the effectiveness of romosozumab plus active vitamin D3 combination therapy. However, there were no differences in bone union evaluated using soft X-ray imaging, indicating no acceleration of fracture healing.ConclusionsAlthough romosozumab and active vitamin D3 combination therapy increased trabecular bone volume, there was no evidence on its ability to accelerate fracture healing.Graphical abstract

Once-weekly parathyroid hormone combined with ongoing long-term alendronate treatment promotes osteoporotic fracture healing in ovariectomized rats.

This study examined the effect of once-weekly parathyroid hormone (PTH) combined with alendronate upon osteoporotic fracture healing after long-term alendronate anti-osteoporosis therapy. Seventy-six 12-week-old female Sprague-Dawley rats were either sham operated or bilaterally ovariectomized (OVX). Following confirmation of osteoporosis 3 months after OVX, the remaining 64 animals received alendronate therapy. After 3 months of alendronate treatment, all rats underwent unilateral transverse tibial osteotomy. Animals were immediately randomly assigned to one of four groups: (1) alendronate followed by vehicle (ALN-VEH), (2) continuation of alendronate (ALN-ALN), (3) alendronate followed by once-weekly PTH alone (ALN-PTH), (4) continuation of alendronate combined with once-weekly PTH (ALN-ALN + PTH) until collection at 4 or 8 weeks after osteotomy. The fractured tibia was assessed using x-ray, dual-energy x-ray absorptiometry, microcomputed tomography, biomechanical testing, histology, and sequential fluorescence labeling. The ALN-ALN + PTH treatment significantly increased total callus volume, mineralized callus volume, mineralized callus volume/total callus volume, and biomechanical strength of the callus relative to ALN-VEH and ALN-PTH treatments at both 4 and 8 weeks and produced more mature trabecular bone compared with ALN-ALN treatment at 8 weeks. RANKL/osteoprotegerin (OPG) are osteoclastogenesis markers, while cluster of differentiation 31 (CD31) is an important marker of angiogenesis. Qualitative immunohistochemical analysis revealed that CD31 and OPG expression was was strong after ALN-ALN + PTH compared with ALN-ALN treatment, whereas RANKL expression was weak after ALN-ALN + PTH versus ALN-PTH treatment. Our study showed that once-weekly PTH combined with alendronate was beneficial in promoting the healing of fractures acquired after long-term alendronate therapy in OVX-induced osteoporotic rats.

Icariin Promotes Fracture Healing in Ovariectomized Rats

BackgroundOsteoporotic fractures are common in postmenopausal women and associated with complications. Numerous studies have demonstrated that icariin can be used to treat fractures and osteoporosis. Herein, we evaluated the efficacy of gavage-administered icariin to promote fracture healing in postmenopausal osteoporotic fracture (POF) rats.Material/MethodsIn this study, ovariectomy-induced POF rats were treated with 600 mg/kg icariin. Micro-computed tomography (micro-CT) was used to assess fracture healing; besides, serum APK, TRACP-5b, and E2 expression levels were detected by commercial kits, and the uterine index was calculated. In addition, the expression of osteogenesis-related proteins (Runx 2 and COL1A2) in the callus was measured by western blot, whereas the expression of OPG/RANKL pathway proteins was measured by western blot and immunohistochemical analysis.ResultsOur data revealed that icariin promoted the expression level of Runx 2 and COL1A2 and suppressed the expression level of serum bone turn over biomarkers via the OPG/RANKL pathway. Besides, a more mature callus was observed in the POF rats receiving icariin than in the untreated POF rats, while serum E2 and uterine index were unaffected by icariin treatment.ConclusionsThese results revealed that icariin could promote fracture healing in ovariectomized rats via OPG/RANKL signaling, and that serum E2 and uterine index were not affected by icariin treatment.

Regulatory effect of mechanical vibration on fibroblast growth factor 23 antibody during fracture healing in ovariectomized rats

Objective To investigate the regulatory effect of mechanical vibration intervention on endocrine hormone fibroblast growth factor23 (FGF23) in ovariectomized fracture rats. Methods A model of postmenopausal osteoporosis was established in 45 female rats, and the animals were randomly divided into three groups: Sham operation group (Sham, n=15), ovariectomized fracture model group (OVX, n=15) and ovariectomized fracture vibration group (OVX-V, n=15). The rats in OVX-V group were subjected to whole-body vibration at a frequency of 35 Hz, a vibration amplitude of 2 mm, and an acceleration of 0.5 g, 20 min/d and 5 t/w, 5 days after fracture surgery. The rats in Sham group and OVX group were placed on the vibrating table for 20 min at 5th day after the operation, and no vibration was performed. Western blotting was used to detect the expression of FGF23 protein in the fracture end of rats. SPSS 19.0 statistical software was used to analyze the results. The results were expressed as mean±standard deviation (Mean±SD). Comparisons between groups were analyzed by one-way ANOVA. Results The protein expression of FGF23 in the fracture end of OVX-V group was significantly lower than that in OVX group at 2nd, 4th and 6th week [(0.846±0.012, 1.315±0.021, 1.315±0.021) vs. (0.703±0.009, 0.466±0.011, 0.380±0.005), P<0.01]. . The protein expression of FGF23 in the fracture end of OVX group was significantly higher than that in Sham group at 2nd, 4th and 6th week [(0.168±0.004, 0.321±0.003, 0.417±0.009) vs. (0.846±0.012, 1.315±0.021, 1.315±0.021), P<0.01), showing an increasing trend, suggesting that mechanical vibration can reduce the expression level of FGF23 in the bone tissue of oarotomy rats. Conclusion Mechanical vibration can reduce the expression of FGF23 in bone tissue, promote osteoblast differentiation, regulate bone mineralization and promote postmenopausal osteoporosis fracture healing. Key words: Mechanical vibration; Osteoporosis; Fracture; Endocrine hormones; Fibroblast growth factor23

Sustained-release of sclerostin single-chain antibody fragments using poly(lactic-co-glycolic acid) microspheres for osteoporotic fracture repair.

Osteoporotic fracture is one of the most common bone diseases in middle and old age, as the most serious consequence of osteoporosis. Sclerostin single‐chain antibody fragments (SCL‐scFv) have been proven to promote bone formation by binding to scleroprotein, a natural antagonist of the Wnt pathway, but it is difficult to rule alone due to the weak permeability and immunogenicity. Herein, we prepared poly(lactic‐co‐glycolic acid) microspheres as a sustained‐release vehicle to prolong the activity of SCL‐scFv. The morphology of microspheres were uniform and nearly sphere, loading efficiency and encapsulation efficiency of SCL‐scFv microspheres were 6.28 ± 1.04% and 48.37 ± 8.11%, respectively. Approximately 90% of the SCL‐scFvs were released from the microspheres over 28 days with initial burst releasing (38%) in the first 4 days. Sustained‐release of active SCL‐scFv from microspheres promoted bone marrow mesenchymal stem cells osteogenic differentiation in vitro and enhanced fracture healing in ovariectomized rats by improving bone mass and bone formation in the fracture region. All these findings demonstrate that the microspheres are able to simultaneously achieve localized long‐term SCL‐scFv controlled release and effectively promote bone formation, which provides a promising approach for osteoporotic fracture.

Therapeutic effects of whole-body vibration on fracture healing in ovariectomized rats: a systematic review and meta-analysis.

Whole-body vibration (WBV), providing cyclic mechanical stimulation, has been used to accelerate fracture healing in preclinical studies. This study aimed to summarize and evaluate the effects of WBV on bone healing in ovariectomized rat models and then analyze its potential effects on fractures in human postmenopausal osteoporosis. PubMed, EMBASE, Web of Science, China National Knowledge Infrastructure, VIP, SinoMed, and WanFang databases were searched from their inception date to September 2017, and an updated search was conducted in January 2018. Studies that evaluated the effects of WBV on bone healing compared with control groups in ovariectomized rats were included. Two authors selected studies, extracted data, and assessed the methodological quality. Meta-analyses were performed when the same outcomes were reported in two or more studies. Nine eligible studies were selected. In treatment groups, callus areas were significantly improved in the first 3 weeks, normalized total bone volume and total tissue volume values increased dramatically at 8 weeks, and the mechanical tests showed a significant difference at the end point of the study. This study suggested that WBV could accelerate callus formation in the early phase of bone healing, promote callus mineralization and maturity in the later phase, and restore mechanical properties of bones.

Gene Therapy with Tetracycline-Regulated Human Recombinant COLIA1 cDNA Direct Adenoviral Delivery Enhances Fracture Healing in Osteoporotic Rats.

A number of previous studies have indicated that the genetic variation at the collage type I alpha 1 (COLIA1) gene locus influences susceptibility to osteoporosis. However, seldom have studies reported the effect of gene delivery using an adenovirus vector carrying human recombinant COLIA1 cDNA on stimulating osteogenic activity of osteoblasts and enhancing fracture healing of ovariectomized rats. The current study was performed to demonstrate whether direct gene delivery using an adenovirus vector carrying human recombinant COLIA1 cDNA could stimulate osteogenic activity of osteoblast in vitro and enhance fracture healing of ovariectomized rats in vivo. In vitro, the tet-on system regulated COLIA1 gene adenovirus was constructed and transfected to osteoblasts. COLIA1 mRNA and collagen type I levels were assessed by reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay to determine whether adenovirus transfected successfully. Osteogenic activity of the osteoblasts was assessed by alkaline phosphatase activity, immunohistochemical staining, immunofluorescent staining, mineralized matrix formation, and extracellular calcium levels. In vivo, adenovirus-delivered COLIA1 gene was injected into the fracture site of the tibia in an ovariectomized rat model of osteoporosis, and bone callus condition was assessed to determine whether the COLIA1 gene could accelerate osteoporotic fracture healing. In vitro, the results showed that COLIA1 gene adenovirus transfection could increase osteoblast COLIA1 gene expression and collagen type I protein synthesis, increase alkaline phosphatase activity, and stimulate calcium nodules formation, which exhibited a direct osteogenic effect on the osteoblasts. In vivo, local injection of COLIA1 gene adenovirus increased collagen type I expression, restored bone mineral density, and accelerated fracture healing in ovariectomized rats, without increasing serum collagen type I and liver COLIA1 mRNA levels. This study suggests direct gene delivery using an adenovirus carrying human COLIA1 cDNA can stimulate the osteogenic activity of osteoblasts in vitro and enhance bone fracture healing in vivo. The tet-on system is an ideal gene regulatory system for effective and safe regulation of the therapeutic gene.

Local application of an ibandronate/collagen sponge improves femoral fracture healing in ovariectomized rats.

Non-union is a major clinical problem in the healing of fractures, especially in patients with osteoporosis. The systemic administration of drugs is time consuming and large doses are demanding and act slowly, whereas local release acts rapidly, increases the quality and quantity of the bone tissue. We hypothesize that local delivery demonstrates better therapeutic effects on an osteoporotic fracture. The aim of this paper is to investigate the effect of the local application of ibandronate loaded with a collagen sponge on regulating bone formation and remodeling in an osteoporotic rat model of fracture healing. We found that the local delivery of ibandronate exhibited excellent effects on improving the bone microarchitecture and suppressed effects on bone remodeling. At 4 weeks, more callus formation and improvement of mechanical character and microstructure were observed in a local delivery via μCT, mechanical test, histological research and serum analysis. The suppression of bone remodeling was compared with a systemic treatment at 12 weeks, and the structural mechanical properties and microarchitecture were also improved with local delivery. This research identifies an earlier, safer and integrated approach for local delivery of ibandronate with collagen and provides a better strategy for the treatment of osteoporotic fracture in rats.

Parathyroid hormone (1–34) promotes fracture healing in ovariectomized rats with type 2 diabetes mellitus

Reports about effects of PTH plus insulin on callus formation of osteoporotic fracture with T2DM were limited. This study was designed to investigate the effects of the combination of PTH and insulin on fracture healing in OVX rats with T2DM. Two-month-old female rats were randomly divided into five groups: normal fracture (F), OVX fracture (OF), T2DM+OVX fracture (DOF), insulin-treated (2-4u/daylight, 4-6u/night, DOFI), and treated with insulin and PTH (50μg/kg/day, 5days/week, DOFIP). A closed mid-shaft fracture was established in the right femurs of all rats after 6weeks of OVX. Rats were euthanized at 2 and 3weeks post-fracture according to the time schedule, respectively. The administration of insulin alone or insulin combined with PTH significantly increased mineralized bone volume fraction (BV/TV) and connectivity density (Conn.D) compared with those of the DOF group at 3weeks post-fracture and also increased cartilaginous callus area ratio in the DOFI and DOFIP groups at 2weeks and bony callus area ratio in the DOFIP groups at both the 2 and 3weeks post-fracture. OVX rats with T2DM exhibited a marked delay in the fracture healing process; insulin treatment ameliorated these effects, and the healing process was enhanced following treatment with a combination of insulin and PTH.

Bone graft substitutes and bone morphogenetic proteins for osteoporotic fractures: what is the evidence?

Despite improvements in implants and surgical techniques, osteoporotic fractures remain challenging to treat. Among other major risk factors, decreased expression of morphogenetic proteins has been identified for impaired fracture healing in osteoporosis. Bone grafts or bone graft substitutes are often used for stabilizing the implant and for providing a scaffold for ingrowth of new bone. Both synthetic and naturally occurring biomaterials are available. Products generally contain hydroxyapatite, tricalcium phosphate, dicalcium phosphate, calcium phosphate cement, calcium sulfate (plaster of Paris), or combinations of the above. Products have been used for the treatment of osteoporotic fractures of the proximal humerus, distal radius, vertebra, hip, and tibia plateau. Although there is generally consensus that screw augmentation increased the biomechanical properties and implant stability, the results of using these products for void filling are not unequivocal. In osteoporotic patients, Bone Morphogenetic Proteins (BMPs) have the potential impact to improve fracture healing by augmenting the impaired molecular and cellular mechanisms. However, the clinical evidence on the use of BMPs in patients with osteoporotic fractures is poor as there are no published clinical trials, case series or case studies. Even pre-clinical literature on in vitro and in vivo data is weak as most articles focus on the beneficial role for BMPs for restoration of the underlying pathophysiological factors of osteoporosis but do not look at the specific effects on osteoporotic fracture healing. Limited data on animal experiments suggest stimulation of fracture healing in ovariectomized rats by the use of BMPs. In conclusion, there is only limited data on the clinical relevance and optimal indications for the use of bone graft substitute materials and BMPs on the treatment of osteoporotic fractures despite the clinical benefits of these materials in other clinical indications. Given the general compromised outcome in osteoporotic fractures and limited alternatives for enhancement of fracture healing, clinicians and researchers should focus on this important topic and provide more data in this field in order to enable a sound clinical use of these materials in osteoporotic fractures.

Piper Sarmentosum: A New Hope for the Treatment of Osteoporosis

Osteoporosis is a major global health problem. Osteoporosis is characterized by the loss of bone mass and strength which leads to an increased risk of fracture. Glucocorticoid treatment is the leading cause of secondary osteoporosis. Glucocorticoid action in bone depends upon the expression of 11beta-hydroxysteroid dehydrogenase type 1 enzyme (11β-HSD1). The oestrogen deficient state causes osteoporosis due to enhancement of osteoclastogenesis by oxidative stress which leads to increased bone resorption. Piper sarmentosum (Daun Kaduk) is commonly used in the local cuisine of South East Asia. It is also traditionally used to treat many diseases such as inflammation, dermatitis and joint pain. Studies have revealed antioxidant properties through its flavonoids compound naringenin which acts as a superoxide scavenger that may help in the endogenous antioxidant defence system to protect bone against osteoporosis. Recent studies found that Ps extract has the ability to inhibit the expression and activity of 11β-HSD1 in adipose tissue and bone which restored bone structure and strength. It also accelerates fracture healing in the oestrogen deficient state through its antioxidant properties. The cost of conventional treatment is high and together with the adverse effects it leads to noncompliance. Treatment modalities with herbal medicine, less side effects and is cheaper need to be explored.This review focused on the therapeutic effect of Ps extract on fracture healing in ovariectomized rats and its protective effects against glucocorticoid induced osteoporotic rats.

Intermittent Administration of Human Parathyroid Hormone before Osteosynthesis Stimulates Cancellous Bone Union in Ovariectomized Rats

It has been reported that intermittent administration of human parathyroid hormone (h-PTH) promotes bone healing after surgery for osteoporotic fractures. If bone healing is promoted by the administration of h-PTH during pre-operative waiting period, we can prevent prolonged bed rest. Therefore, we evaluated the effects of pre-operative h-PTH treatment on cancellous bone union and its mechanism for fracture healing in ovariectomized rats as a model for osteoporosis. Ovariectomized 7-month-old female Sprague-Dawley rats underwent an osteotomy of the proximal tibia as a fracture model, and h-PTH (30 μg/kg body weight) or vehicle was administered as a pre-operative treatment for one week. After the one-week treatment, tibiae were fixed with wire for osteosynthesis, and h-PTH or vehicle was administered for 1 or 3 weeks following wire fixation. In addition to bone histomorphometry, we used alcian blue/hematoxylin stained sections for evaluating cartilage volume and immunostained sections for analyzing the expression of proliferating cell nuclear antigen (PCNA) for cell proliferation and that of Sox9 and Runx2, differentiation markers for cartilage cells and osteoblasts, respectively. Pre-operative treatment with PTH significantly increased bone volume. Pre-operative and pre- to post-operative treatment with PTH for 2 weeks significantly promoted bone union. Pre-operative treatment with PTH significantly increased cartilage volume, and pre- to post-operative treatment with PTH for 2 weeks significantly increased the percentage of cells positive for Runx2 (p < 0.01), but not PCNA or Sox9. Pre-operative administration of h-PTH enhances bone union by promoting cartilage formation and cell differentiation to osteoblasts, but not by promoting cell proliferation.

Locally Administrated Perindopril Improves Healing in an Ovariectomized Rat Tibial Osteotomy Model

Angiotensin-converting enzyme inhibitors are widely prescribed to regulate blood pressure. High doses of orally administered perindopril have previously been shown to improve fracture healing in a mouse femur fracture model. In this study, perindopril was administered directly to the fracture area with the goal of stimulating fracture repair. Three months after being ovariectomized (OVX), tibial fractures were produced in Sprague–Dawley rats and subsequently stabilized with intramedullary wires. Perindopril (0.4 mg/kg/day) was injected locally at the fractured site for a treatment period of 7 days. Vehicle reagent was used as a control. Callus quality was evaluated at 2 and 4 weeks post-fracture. Compared with the vehicle group, perindopril treatment significantly increased bone formation, increased biomechanical strength, and improved microstructural parameters of the callus. Newly woven bone was arranged more tightly and regularly at 4 weeks post-fracture. The ultimate load increased by 66.1 and 76.9% (p<0.01), and the bone volume over total volume (BV/TV) increased by 29.9% and 24.3% (p<0.01) at 2 and 4 weeks post-fracture, respectively. These findings suggest that local treatment with perindopril could promote fracture healing in ovariectomized rats.

Expression of TGF-β1 in the blood during fracture repair in an estrogen-deficient rat model

OBJECTIVES:Previous studies have reported that osteoporosis due to estrogen deficiency influences fracture healing. Transforming growth factor (TGF-β) has been found to be involved in fracture healing via the regulation of the differentiation and activation of osteoblasts and osteoclasts. The current study aimed to determine the effects of estrogen on the expression of TGF-β1 during fracture healing in ovariectomized rats.METHODS:Thirty female Sprague-Dawley rats weighing 200–250 g were assigned to: (i) a sham-operated group that was given a normal saline; (ii) an ovariectomized control group that was given a normal saline; or (iii) an ovariectomized + estrogen (100 µg/kg/day) group that was treated with conjugated equine estrogen. The right femur of all rats was fractured, and a Kirschner wire was inserted six weeks post-ovariectomy. Treatment with estrogen was given for another six weeks post-fracture. At the end of the study, blood samples were taken, and the right femur was harvested and subjected to biomechanical strength testing.RESULTS:The percentage change in the plasma TGF-β1 level before treatment was significantly lower in the ovariectomized control and estrogen groups when compared with the sham group (p<0.001). After six weeks of treatment, the percentage change in the plasma TGF-β1 level in the estrogen group was significantly higher compared with the level in the ovariectomized control group (p = 0.001). The mean ultimate force was significantly increased in the ovariectomized rats treated with estrogen when compared with the ovariectomized control group (p = 0.02).CONCLUSION:These data suggest that treatment with conjugated equine estrogen enhanced the strength of the healed bone in estrogen-deficient rats by most likely inducing the expression of TGF-β1.

Simvastatin promotes femoral fracture healing in ovariectomized rats

Objective: Previous studies have reported osteoporosis delayed fracture healing, and research about the influence of statins on bone formation and fracture healing is increasing. The present study was to study the effects of simvastatin on osteoporotic fracture healing by treating the rat model with bilateral ovariectomies and femur fracture operations. Methods: The osteoporotic rat model was established by bilateral ovariectomies in 12-weekold female Sprague-Dawley rats, and was successfully confirmed by dual-energy X-ray absorptiometry (DXA) detection of bonemineral density 4 weeks later. Right midshaft femur facture model was established 4 weeks after ovariectomy and fixed intramedullaryly, administered with simvastatin once per two days (5 mg/kg) or equal volume of normal saline. Right femurs were harvested the 6thweek after the fracture operation for the CR films and (DEXA) bone mineral density measurements, and then were decalcified for paraffin sections, and stainedwithHE BMD assessment revealed a significantly increasedmBMDof the simvastatin group than that of the vehicle group, though an increased tBMD and dBMD were also observed in simvastatin treated rats. No significant difference could be detected compared to the vehicle group; and expression levels of BMP-2 and VEGF, but not TRAP, of the simvastatin treatment group were significantly higher than those of the vehicle group. Conclusions: Simvastatin treatment accelerates the fracture healing in ovariectomized rats, improving woven bone to remodel into lamellar bone and increasing the expression of BMP-2 and VEGF probably participates in this process.

Yeast-Incorporated Gallium Promotes Fracture Healing by Increasing Callus Bony Area and Improving Trabecular Microstructure on Ovariectomized Osteopenic Rats

The purpose of this study was to analyze the impact of yeast-incorporated gallium on fracture healing in ovariectomized osteopenic rats. Forty Wistar female rats used were divided into three groups: sham-operated rats (SHAM), ovariectomized (OVX) rats, and ovx rats treated with yeast-bound gallium (YG). A standardized fracture-healing model with stable plate fixation was established for rat femoral. After 4-week stable fixation, animals were killed to prepare bones for Micro-CT, biomechanical testing, and histomorphometry. In addition, bone samples were obtained to evaluate the content of mineral substances in bones. Quantitative analysis of the bones from animals in the organic gallium group revealed significantly increased mineral contents compared to bones from OVX and SHAM groups. Micro-CT showed that treatment with yeast-incorporated gallium increased BV/TV and trabecular thickness and decreased trabecular separation in ovx animals. Histomorphometric evaluation demonstrated that YG increased callus area and callus bone formation. Yeast-bound gallium also improved the biomechanical properties of bone healing. In conclusion, this study suggests that yeast-incorporated gallium could promote fracture healing in ovariectomized rats.

Systemic treatment with strontium ranelate promotes tibial fracture healing in ovariectomized rats

Systemic treatment with strontium ranelate (SR) was performed on ovariectomized (OVX) rats with fractured tibiae. Callus quality was assessed by radiographic, histological, micro-computerized tomography, and biomechanical examinations at 4 and 8 weeks after fracture. Results revealed that systemic applied SR promoted osteoporotic fracture healing. Several studies have demonstrated the dual effect of SR on osteoporotic and undisturbed bone. However, reports of their effect on osteoporotic fracture healing are limited. This study was designed to investigate the effects of SR on bone regeneration in OVX rats with fractured tibiae. Three months after being OVX, female Sprague-Dawley rats accepted bilateral osteotomy on proximal tibiae fixed with intramedullary wires and were divided into two groups: OVX and OVX + SR (625 mg/kg/day). Callus quality was evaluated at 4 and 8 weeks postfracture. Compared with OVX group, SR treatment significantly increased bone formation, BMD, biomechanical strength, and improved microstructural properties of the callus. The ultimate load was increased by 211.0% and 61.4% (p<0.01), and the total bone volume of callus by 74.8% and 79.3% (p<0.01) at 4 and 8 weeks postfracture, respectively. SR treatment also promoted healing progress with increased osteogenesis at 4 weeks; more mature and tightly arranged woven or lamellar bone at 8 weeks across the fracture gap in histological analysis. This study suggests that systemic treatment with strontium ranelate could promote tibial fracture healing in OVX rats.

Locally applied simvastatin promotes fracture healing in ovariectomized rat

Simvastatin solution was injected subcutaneously to the site of fractured tibiae of ovariectomized rats. Afterwards healing quality was evaluated by morphologic, radiographic, biomechanical, histological and histomorphometric methods at 1, 2 and 4 weeks after fracture. Results showed that locally applied simvastatin improved fracture healing. Many studies have documented an anabolic effect of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, statins, on undisturbed bone. Reports of their effects, however, on fractured skeletal systems have been limited. A study was, therefore, conducted to check the effects of statins on fracture healing. Simvastatin (10 mg/kg/day) was injected subcutaneously to tissue overlying the site of fractured tibiae of ovariectomized rats for a treatment period of 5 days. Vehicle reagent was used as a control. Healing quality was evaluated at 1, 2 and 4 weeks after fracture. Compared with that in the vehicle group, the callus cross-section area in simvastatin-treated rats was significantly enlarged by 21.3% (p < 0.05) at 1 week and by 21.5% (p < 0.05) at 2 weeks; new woven bone was relatively substantive and arranged more tightly and regularly at 2 and 4 weeks; and maximal load was increased by 57.5% (p < 0.05) at 2 weeks and by 31.4% (p < 0.05) at 4 weeks. Histomorphometrically, simvastatin was associated with a significant (p < 0.05) increase of mineralization width (MLW), mineralization volume (MLV) and mineral apposition rate (MAR). The current study suggests that local application of simvastatin could promote fracture healing in ovariectomized rats.

Effect of intermittent administration of parathyroid hormone on fracture healing in ovariectomized rats.

The effects of intermittent administration of parathyroid hormone on fracture healing in ovariectomized rats were examined to evaluate its potential use as a therapeutic agent for osteoporotic fractures. Three months postovariectomy, bilateral tibial shaft fractures were induced and stabilized by intramedullary nailing with Kirschner wires. Saline, 17beta-estradiol (Sigma Chemical Corp, St Louis, Mo), or recombinant human parathyroid hormone (1-84) (Korean Green-Cross Pharm Corp, Seoul, Korea) was given once a day for 30 consecutive days during fracture healing. Fracture healing was assessed by morphometric and mechanical analysis of fracture callus. Intermittent parathyroid hormone administration increased the morphometric and mechanical parameters in a dose-dependent manner. A bone-resorption inhibiting agent, 17beta-estradiol did not offer advantage in terms of fracture healing in ovariectomized rats. Findings suggest intermittent parathyroid hormone administration may benefit osteoporosis and fracture.