Promotion of fracture healing by vitamin E in rats

Patients Undergoing Surgery for Hip Fractures Suffer from Severe Oxidative Stress as Compared to Patients with Hip Osteoarthritis Undergoing Total Hip Arthroplasty

Hip fractures are associated with the highest degree of morbidity and mortality of all fractures in elderly patients and pose a major risk for subsequent fractures. Patients with hip fractures also present accelerated bone turnover despite early stable fracture fixation and early mobilization. We aimed to evaluate oxidative stress in two groups of patients (25 patients each, matched for age, side, and BMI) who underwent internal fixation of hip fractures and total hip arthroplasty for hip osteoarthritis. Blood samples were taken from all patients during admission, the day of surgery, the 4^th postoperative day, and the 15^th postoperative day. Reduced (GSH) and oxidized (GSSG) glutathione, GSH/GSSG, catalase (CAT), thiobarbituric acid reactive substances (TBARS), protein carbonyls (PC), and total antioxidant capacity (TAC) as a widely used battery of redox biomarkers were recorded from blood samples. Patients with hip fractures who undergo fixation surgery, compared to those with hip osteoarthritis, suffer significant oxidative stress with an active but insufficient first line of oxidative defense, an intensive first line reaction, a very active second line of oxidative defense, and a low plasma antioxidant capacity. Surgery worsened already present lipid- and protein-related tissue damage. The severe oxidative stress observed may explain high morbidity and mortality rates and high bone turnover status, as well as the high incidence of refractures. Furthermore, the question of whether antioxidant therapy measures should be introduced in the management of hip fracture patients is raised.

Circulating Alpha-Tocopherol Levels, Bone Mineral Density, and Fracture: Mendelian Randomization Study

Recent cohort studies indicate a potential role of the antioxidant α-tocopherol in reducing bone loss and risk of fractures, especially hip fractures. We performed a Mendelian randomization investigation of the associations of circulating α-tocopherol with estimated bone mineral density (eBMD) using heel ultrasound and fractures, identified from hospital records or by self-reports and excluding minor fractures. Circulating α-tocopherol was instrumented by three genetic variants associated with α-tocopherol levels at p < 5 × 10^-8 in a genome-wide association meta-analysis of 7781 participants of European ancestry. Summary-level data for the genetic associations with eBMD in 426,824 individuals and with fracture (53,184 cases and 373,611 non-cases) were acquired from the UK Biobank. Two of the three genetic variants were strongly associated with eBMD. In inverse-variance weighted analysis, a genetically predicted one-standard-deviation increase of circulating α-tocopherol was associated with 0.07 (95% confidence interval, 0.05 to 0.09) g/cm² increase in BMD, which corresponds to a >10% higher BMD. Genetically predicted circulating α-tocopherol was not associated with odds of any fracture (odds ratio 0.97, 95% confidence interval, 0.91 to 1.05). In conclusion, our results strongly strengthen a causal link between increased circulating α-tocopherol and greater BMD. Both an intervention study in those with a low dietary intake of α-tocopherol is warranted and a Mendelian randomization study with fragility fractures as an outcome.

Evaluation of the effects of vitamins C and E on experimental orthodontic tooth movement

Background. This experimental study aimed to assess the effects of Vitamins C and E on orthodontic tooth movement.

Methods. Fifty-one male Wistar albino rats were divided into six groups: five appliance groups and one control group. The appliance groups had an orthodontic appliance consisting of a closed-coil spring ligated between the maxillary incisor and maxillary first molar (50 g). Vitamin E and C (150 mg/kg) were injected intraperitoneally per day in the first and second groups, respectively. Vitamins E and C (20 μL) were locally injected into the periodontal gap of the moving teeth in the third and fourth groups, respectively, once every three days. No vitamin was injected in the last (fifth) appliance group.The experimental period was 18 days. Histological and biochemical (alkaline phosphatase, osteocalcin, and NTx levels) evaluations of the samples were performed, and maxillary incisor‒molar distance was measured before and after the experiment.

Results. The amount of tooth movement was similar in the appliance groups. All the vitamin groups showed significantly increased osteoblastic activity, while those treated with systemic vitamins exhibited significantly increased numbers of collagen fibers on the tension side compared to the appliance control group (P<0.05).

Conclusion. Vitamin C and E supplements positively affected bone formation on the tension side of the teeth during experimental orthodontic tooth movement.

Advances and Promises of Nutritional Influences on Natural Bone Repair

Impaired fracture healing continues to be a significant public health issue. This is more frequently observed in aging populations and patients with co-morbidities that can directly influence bone repair. Tremendous progress has been made in the development of biologics to enhance and accelerate the healing process; however, side-effects persist that can cause significant discomfort and tissue damage. This has been the impetus for the development of safe and natural strategies to hasten natural bone healing. Of the many possible approaches, nutrition represents a safe, affordable, and non-invasive strategy to positively influence each phase of fracture repair. However, our understanding of how healing can be hindered by malnutrition or enhanced with nutritional supplementation has lagged behind the advancements in both surgical management and the knowledge of molecular and cellular drivers of skeletal fracture repair. This review serves to bridge this knowledge gap as well as define the importance of nutrition during fracture healing. The extant literature clearly indicates that pre-existing nutritional deficiencies should be corrected, and nutritional status should be carefully monitored to prevent the development of malnutrition for the best possible healing outcome. It remains unclear, however, whether the provision of nutrients beyond sufficiency has any benefit on fracture repair and patient outcomes. The combined body of pre-clinical studies using a variety of animal models suggests a promising role of nutrition as an adjuvant therapy to facilitate fracture repair, but extensive research is needed, specifically at the clinical level, to clarify the utility of nutritional interventions in orthopedics. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:695-707, 2020.

Dysfunctional stem and progenitor cells impair fracture healing with age

Successful fracture healing requires the simultaneous regeneration of both the bone and vasculature; mesenchymal stem cells (MSCs) are directed to replace the bone tissue, while endothelial progenitor cells (EPCs) form the new vasculature that supplies blood to the fracture site. In the elderly, the healing process is slowed, partly due to decreased regenerative function of these stem and progenitor cells. MSCs from older individuals are impaired with regard to cell number, proliferative capacity, ability to migrate, and osteochondrogenic differentiation potential. The proliferation, migration and function of EPCs are also compromised with advanced age. Although the reasons for cellular dysfunction with age are complex and multidimensional, reduced expression of growth factors, accumulation of oxidative damage from reactive oxygen species, and altered signaling of the Sirtuin-1 pathway are contributing factors to aging at the cellular level of both MSCs and EPCs. Because of these geriatric-specific issues, effective treatment for fracture repair may require new therapeutic techniques to restore cellular function. Some suggested directions for potential treatments include cellular therapies, pharmacological agents, treatments targeting age-related molecular mechanisms, and physical therapeutics. Advanced age is the primary risk factor for a fracture, due to the low bone mass and inferior bone quality associated with aging; a better understanding of the dysfunctional behavior of the aging cell will provide a foundation for new treatments to decrease healing time and reduce the development of complications during the extended recovery from fracture healing in the elderly.

Silicon nitride enhances osteoprogenitor cell growth and differentiation via increased surface energy and formation of amide and nanocrystalline HA for craniofacial reconstruction

The bioactive silicon nitride (Si₃N₄) has been FDA cleared for use as spinal intervertebral arthrodesis devices. Because its surface properties promote bone ongrowth and ingrowth, it also has the potential to benefit craniofacial reconstruction. Thus, the aim of this work was to determine whether the surface properties of Si₃N₄ could enhance the osteoblast cell growth, differentiation and nucleation of hydroxyapatite (HA) crystals compared to conventional implant materials such as titanium (Ti) and polyether ether ketone (PEEK). X-ray absorbance near-edge structure analysis (XANES) indicated the presence of Si-Si, Si-O and Si-N bonding. Surface wettability studies confirmed that Si₃N₄ exhibits the lowest contact angle and highest surface energy. Cell culture studies showed that osteoblast growth was enhanced on Si₃N₄ after 1 day and up to 7 days. Si₃N₄ surface induced highest surface coverage and thickness of nanocrystalline HA (211) and (203) in cell-free in vitro studies after 7 days of culture. Raman spectroscopy analysis confirmed the presence of surface functional groups consisting of phosphate and carbonate species. Interestingly, Si₃N₄ surface showed amide and hydroxyproline groups, the precursors to collagen, which were not observed on Ti and PEEK surfaces. Furthermore, Si₃N₄ surface indicated high expression of RUNX2, enhanced cell differentiation and dense collagenous ECM after 30 days of the in vitro study. The present study concluded that Si₃N₄ surface enhances osteoprogenitor cell adhesion, growth, RUNX2 expression and ECM formation via the coupled effects of higher surface energy and the presence of amide and nanocrystalline HA functional groups.

The Molecular Mechanism of Vitamin E as a Bone-Protecting Agent: A Review on Current Evidence

Bone remodelling is a tightly-coordinated and lifelong process of replacing old damaged bone with newly-synthesized healthy bone. In the bone remodelling cycle, bone resorption is coupled with bone formation to maintain the bone volume and microarchitecture. This process is a result of communication between bone cells (osteoclasts, osteoblasts, and osteocytes) with paracrine and endocrine regulators, such as cytokines, reactive oxygen species, growth factors, and hormones. The essential signalling pathways responsible for osteoclastic bone resorption and osteoblastic bone formation include the receptor activator of nuclear factor kappa-B (RANK)/receptor activator of nuclear factor kappa-B ligand (RANKL)/osteoprotegerin (OPG), Wnt/β-catenin, and oxidative stress signalling. The imbalance between bone formation and degradation, in favour of resorption, leads to the occurrence of osteoporosis. Intriguingly, vitamin E has been extensively reported for its anti-osteoporotic properties using various male and female animal models. Thus, understanding the underlying cellular and molecular mechanisms contributing to the skeletal action of vitamin E is vital to promote its use as a potential bone-protecting agent. This review aims to summarize the current evidence elucidating the molecular actions of vitamin E in regulating the bone remodelling cycle.

Strong binding active constituents of phytochemical to BMPR1A promote bone regeneration: In vitro, in silico docking, and in vivo studies

Two of the most problematic orthopedic and neurosurgeon visits are associated with spine and craniofacial fractures. Therefore, more attention needs to be paid to finding a medicine to repair these fractures. Amongst the most mysterious herbs, Aloe vera stands out. In the present study, the ameliorating function of A. vera on osteogenesis was studied in vitro and in vivo. Osteoblast-like cells were exposed to A. vera, followed by analysis of cell viability, lactate dehydrogenase release, and intracellular reactive oxygen species (ROS) production. The results showed an enhanced cell biocompatibility in a dose-dependent manner due to attenuated intracellular ROS production. Furthermore, a docking study indicated that the strong affinity of A. vera constituents to type I bone morphogenic protein receptor (BMPR1A) without the involvement of the BMPR1A chain B. The induction of osteogenesis prompts extracellular calcium deposition by osteoblasts, which affirms successful in vitro bone regeneration. However, injection of A. vera in rats with critical size calvarial defects induced Runx2, alkaline phosphatase (ALP), OCN, and BMP2 genes overexpression, which led to the formation of victorious bone with enhanced bone density and ALP activity. It is worthy to note that Aloin has the highest affinity to BMPR1A, whereas there are no reports regarding the impact of Aloenin, Aloesin, and γ-sitosterol on osteogenesis. Furthermore, some of them have antitumor potency, and it might be proposed that they are considered as a bone substitute in the osteotomy site of osteosarcoma with the aim of bone recovery and suppression of osteosarcoma. The whole consequences of this investigation manifests the plausibility of using A. vera as an antioxidant and osteoconductive substitute.

Interleukin-6 as possible early marker of stress response after femoral fracture

Bone fracture healing is a complex process which at best results in full recovery of function and structure of injured bone tissue, but all the mechanisms involved in this process, and their mutual interaction, are not fully understood. Despite advancement of surgical procedures, this type of fractures is still a major public health concern. In the last few decades, a lot of attention is focused on the oxygen-free radicals and inflammatory response markers as important factors of skeletal injury. Thus, the aim of the present study was to follow the changes in redox balance and inflammatory response in elderly patients with femoral fractures during the earliest stages of fracture healing, by measuring the values of the observed markers immediately after fracture, as well as the first, third, and seventh postoperative day. Present study was performed on a group of 65 elderly patients with femoral neck fractures, recruited from the Orthopedic Clinic, Clinical Centre Kragujevac in the period from February to May 2015. Redox status was measured spectrophotometrically and evaluated by measuring the levels of index of lipid peroxidation (measured as TBARS), nitrite (NO₂^-), superoxide anion radical (O₂^-), and hydrogen peroxide (H₂O₂) in plasma, while activities of corresponding antioxidative enzymes, catalase (CAT), superoxide dismutase (SOD), and reduced glutathione (GSH) were measured in erythrocytes. The cytokine concentrations of interleukin (IL)-6 and tumor necrosis factor (TNF)-α were determined in plasma, using ELISA assays specific for human cytokines. Our study showed that redox status and TNF-α in elderly patients with femoral fractures did not show statistically significant changes during the early phase of fracture healing. On the other hand, IL-6 increased statistically in first day after intervention. This preliminary study has shown our observations, and we hope that these results may help in better understanding mechanisms which are included at fracture healing. More importantly, this study attempted to create a platform for further research.

The effect of immunonutrition (glutamine, alanine) on fracture healing

Background

Methods

Results

Conclusion

Amorphous Silica: A New Antioxidant Role for Rapid Critical-Sized Bone Defect Healing

Traumatic fractures cause structurally unstable sites due to severe bone loss. Such fractures generate a high yield of reactive oxygen species (ROS) that can lead to oxidative stress. Excessive and prolonged ROS activity impedes osteoblast differentiation and instigates long healing times. Stimulation of antioxidants such as superoxide dismutase (SOD1), are crucial to reduce ROS, stimulate osteogenesis, and strengthen collagen and mineral formation. Yet, no current fixative devices have shown an ability to enhance collagen matrix formation through antioxidant expression. This study reports plasma-enhanced chemical vapor deposition based amorphous silicon oxynitride (Si(ON)x) as a potential new fracture healing biomaterial that adheres well to the implant surface, releases Si(+4) to enhance osteogenesis, and forms a surface hydroxyapatite for collagen mineral attachment. These materials provide a sustained release of Si(+4) in physiological environment for extended times. The dissolution rate partially depends on the film chemistry and can be controlled by varying O/N ratio. The presence of Si(+4) enhances SOD1, which stimulates other osteogenic markers downstream and leads to rapid mineral formation. In vivo testing using a rat critical-sized calvarial defect model shows a more rapid bone-regeneration for these biomaterials as compared to control groups, that implies the clinical significance of the presented biomaterial.

Intake and serum concentrations of α-tocopherol in relation to fractures in elderly women and men: 2 cohort studies

BACKGROUND

A reduction in the formation of free radicals and oxidative stress might reduce the rate of bone loss and muscle wasting.

OBJECTIVE

The objective was to determine whether α-tocopherol intake or serum concentrations are associated with fracture risk in older women and men.

DESIGN

Two cohort studies, the Swedish Mammography Cohort (SMC; n = 61,433 women) and the Uppsala Longitudinal Study of Adult Men (ULSAM; n = 1138 men), were used.

RESULTS

During 19 y of follow-up, 14,738 women in the SMC experienced a first fracture at any site (3871 hip fractures). A higher hip fracture rate was observed with lower intakes of α-tocopherol. Compared with the highest quintile of intake, the lowest quintile had a multivariable-adjusted HR of 1.86 (95% CI: 1.67, 2.06). The HR of any fracture was 1.20 (95% CI: 1.14, 1.28). α-Tocopherol-containing supplement use was associated with a reduced rate of hip fracture (HR: 0.78; 95% CI: 0.65, 0.93) and any fracture (HR: 0.86; 95% CI: 0.78, 0.94). Compared with the highest quintile of α-tocopherol intake in ULSAM (follow-up: 12 y), lower intakes (quintiles 1-4) were associated with a higher rate of hip fracture (HR: 3.33; 95% CI: 1.43, 7.76) and any fracture (HR: 1.84; 95% CI: 1.18, 2.88). The HR for hip fracture in men for each 1-SD decrease in serum α-tocopherol was 1.58 (95% CI: 1.13, 2.22) and for any fracture was 1.23 (95% CI: 1.02, 1.48).

CONCLUSION

Low intakes and low serum concentrations of α-tocopherol are associated with an increased rate of fracture in elderly women and men.

Influence of caffeic acid phenethyl ester on bone healing in a rat model

OBJECTIVE

To examine the effects of caffeic acid phenethyl ester (CAPE; a component of honey bee-hive propolis with antioxidant, anti-inflammatory, antiviral and anticancer properties) on bone regeneration and fibrotic healing in a rat model.

METHODS

Male Sprague-Dawley rats (n = 63; mean age 7 weeks; weight 280-490 g) were randomly divided into three groups: A, cranial defect with no bone healing treatment (n = 21); B, cranial defect treated with CAPE (n = 21); C, cranial defect treated with CAPE and β-tricalcium phosphate/hydroxyl apatite (n = 21). Rats were anaesthetized with ketamine (8 mg/100 g) by intraperitoneal injection and a cranial critical size bone defect was created. Following surgery, CAPE (10 µmol/kg) was administered by daily intraperitoneal injection. Seven rats in each group were killed at days 7, 15 and 30 following surgery. Bone regeneration, fibrotic healing and osteoblast activity were evaluated by histopathology.

RESULTS

Statistically significant differences in healing were found between all groups. There were no statistically significant within-group differences between day 7 and 15. At day 30, bone healing scores were significantly higher in groups B and C compared with group A.

CONCLUSION

CAPE significantly improved bone-defect healing in a rat model, suggesting that CAPE has beneficial effects on bone healing.

Effects of vitamin e on bone biomechanical and histomorphometric parameters in ovariectomized rats

The present study examined the dose-dependent effect of vitamin E in reversing bone loss in ovariectomized (Ovx) rats. Sprague-Dawley rats were either Sham-operated (Sham) or Ovx and fed control diet for 120 days to lose bone. Subsequently, rats were divided into 5 groups (n = 12/group): Sham, Ovx-control, low dose (Ovx + 300 mg/kg diet; LD), medium dose (Ovx + 525 mg/kg diet; MD), and high dose (Ovx + 750 mg/kg diet; HD) of vitamin E and sacrificed after 100 days. Animals receiving MD and HD of vitamin E had increased serum alkaline phosphatase compared to the Ovx-control group. Bone histomorphometry analysis indicated a decrease in bone resorption as well as increased bone formation and mineralization in the Ovx groups supplemented with MD and HD of vitamin E. Microcomputed tomography findings indicated no effects of vitamin E on trabecular bone of fifth lumbar vertebrae. Animals receiving HD of vitamin E had enhanced fourth lumbar vertebra quality as evidenced by improved ultimate and yield load and stress when compared to Ovx-control group. These findings demonstrate that vitamin E improves bone quality, attenuates bone resorption, and enhances the rate of bone formation while being unable to restore bone density and trabecular bone structure.

Vitamin e and the healing of bone fracture: the current state of evidence

Background. The effect of vitamin E on health-related conditions has been extensively researched, with varied results. However, to date, there was no published review of the effect of vitamin E on bone fracture healing. Purpose. This paper systematically audited past studies of the effect of vitamin E on bone fracture healing. Methods. Related articles were identified from Medline, CINAHL, and Scopus databases. Screenings were performed based on the criteria that the study must be an original study that investigated the independent effect of vitamin E on bone fracture healing. Data were extracted using standardised forms, followed by evaluation of quality of reporting using ARRIVE Guidelines, plus recalculation procedure for the effect size and statistical power of the results. Results. Six animal studies fulfilled the selection criteria. The study methods were heterogeneous with mediocre reporting quality and focused on the antioxidant-related mechanism of vitamin E. The metasynthesis showed α-tocopherol may have a significant effect on bone formation during the normal bone remodeling phase of secondary bone healing. Conclusion. In general, the effect of vitamin E on bone fracture healing remained inconclusive due to the small number of heterogeneous and mediocre studies included in this paper.

The effects of alpha-tocopherol supplementation on fracture healing in a postmenopausal osteoporotic rat model

OBJECTIVE

Osteoporosis increases the risk of bone fractures and may impair fracture healing. The aim of this study was to investigate whether alpha-tocopherol can improve the late-phase fracture healing of osteoporotic bones in ovariectomized rats.

METHOD

In total, 24 female Sprague-Dawley rats were divided into three groups. The first group was sham-operated, and the other two groups were ovariectomized. After two months, the right femora of the rats were fractured under anesthesia and internally repaired with K-wires. The sham-operated and ovariectomized control rat groups were administered olive oil (a vehicle), whereas 60 mg/kg of alpha-tocopherol was administered via oral gavage to the alpha-tocopherol group for six days per week over the course of 8 weeks. The rats were sacrificed, and the femora were dissected out. Computed tomography scans and X-rays were performed to assess fracture healing and callus staging, followed by the assessment of callus strengths through the biomechanical testing of the bones.

RESULTS

Significantly higher callus volume and callus staging were observed in the ovariectomized control group compared with the sham-operated and alpha-tocopherol groups. The ovariectomized control group also had significantly lower fracture healing scores than the sham-operated group. There were no differences between the alpha-tocopherol and sham-operated groups with respect to the above parameters. The healed femora of the ovariectomized control group demonstrated significantly lower load and strain parameters than the healed femora of the sham-operated group. Alpha-tocopherol supplementation was not able to restore these biomechanical properties.

CONCLUSION

Alpha-tocopherol supplementation appeared to promote bone fracture healing in osteoporotic rats but failed to restore the strength of the fractured bone.

Tocotrienol supplementation improves late-phase fracture healing compared to alpha-tocopherol in a rat model of postmenopausal osteoporosis: a biomechanical evaluation

This study investigated the effects of α-tocopherol and palm oil tocotrienol supplementations on bone fracture healing in postmenopausal osteoporosis rats. 32 female Sprague-Dawley rats were divided into four groups. The first group was sham operated (SO), while the others were ovariectomised. After 2 months, the right femora were fractured under anesthesia and fixed with K-wire. The SO and ovariectomised-control rats (OVXC) were given olive oil (vehicle), while both the alpha-tocopherol (ATF) and tocotrienol-enriched fraction (TEF) groups were given alpha-tocopherol and tocotrienol-enriched fraction, respectively, at the dose of 60 mg/kg via oral gavages 6 days per week for 8 weeks. The rats were then euthanized and the femora dissected out for bone biomechanical testing to assess their strength. The callous of the TEF group had significantly higher stress parameter than the SO and OVXC groups. Only the SO group showed significantly higher strain parameter compared to the other treatment groups. The load parameter of the OVXC and ATF groups was significantly lower than the SO group. There was no significant difference in the Young's modulus between the groups. In conclusion, tocotrienol is better than α-tocopherol in improving the biomechanical properties of the fracture callous in postmenopausal osteoporosis rat model.

Fracture healing under healthy and inflammatory conditions

Optimal fracture treatment requires knowledge of the complex physiological process of bone healing. The course of bone healing is mainly influenced by fracture fixation stability (biomechanics) and the blood supply to the healing site (revascularization after trauma). The repair process proceeds via a characteristic sequence of events, described as the inflammatory, repair and remodeling phases. An inflammatory reaction involving immune cells and molecular factors is activated immediately in response to tissue damage and is thought to initiate the repair cascade. Immune cells also have a major role in the repair phase, exhibiting important crosstalk with bone cells. After bony bridging of the fragments, a slow remodeling process eventually leads to the reconstitution of the original bone structure. Systemic inflammation, as observed in patients with rheumatoid arthritis, diabetes mellitus, multiple trauma or sepsis, can increase fracture healing time and the rate of complications, including non-unions. In addition, evidence suggests that insufficient biomechanical conditions within the fracture zone can influence early local inflammation and impair bone healing. In this Review, we discuss the main factors that influence fracture healing, with particular emphasis on the role of inflammation.

Effects of α-tocopherol on the early phase of osteoporotic fracture healing

Fracture healing is a complex process, which is more complicated if the bone is osteoporotic. One of the vitamin E isomers, α-tocopherol, has been found to prevent osteoporosis and improve bone fracture healing but its role in the healing of osteoporotic fractures is still unclear. We carried out a study on the effects of α-tocopherol supplementation on osteoporotic fracture healing using an ovariectomized rat model, whereby we focused on the early phase of fracture healing, that is, the phase with excessive production of free radicals. Twenty-four female Sprague-Dawley rats were divided into three groups: sham-operated (SO), ovariectomized-control (OVC), and ovariectomized + α-tocopherol supplementation (ATF) groups. The right femora of all the rats were fractured at mid-diaphysis and K-wires were inserted for internal fixation. After 2 weeks of treatment, the rats were euthanized and the femora were dissected out for measurement of callous volume by CT-scan and radiological staging of callous formation and fracture healing. The oxidative parameters of the fractured femora were also measured. The results showed that the callous volume and callous staging were not different between the groups. However, the fracture healing stage of the OVC group was lower than the SO group, while α-tocopherol supplementation in the ATF group had improved the healing until it was comparable to the SO group. The activities of the anti-oxidatant enzymes, superoxide dismutase, and glutathione peroxidase in the ATF group were found to be significantly higher than in the OVC group. In conclusion, α-tocopherol improved fracture healing but had no effect on the callous volume and staging. The improvement in fracture healing may be due to the increased activities of the anti-oxidatant enzymes in the bone during the early phase of fracture healing of osteoporotic bone.

Effect of alpha-tocopherol on bone formation during distraction osteogenesis: a rabbit model

Purpose

The purpose of this study was to evaluate the effects of alpha-tocopherol on distraction osteogenesis.

Materials and methods

Right tibias of 30 New Zealand white rabbits were distracted at a rate of 0.5 mm/day for 20 days with a circular external fixator. Experimental group rabbits (n = 15) were administered i.m. 20 mg/kg/day alpha-tocopherol for 30 days. Radiographic examinations were performed at the 20th, 30th and 40th days. Bone scintigraphy was performed at the 5th and 20th days. Serum total antioxidant capacity (TAC) was measured at the 5th and 30th days. All animals were sacrificed and the right tibias of all animals were harvested for histopathologic examination at the 40th day.

Results

Radiologic scores were statistically similar at the 20th day. However, the experimental group demonstrated higher radiologic scores at the 30th and 40th days. A scintigraphic baseline study at the 5th day of the study showed statistically similar osteoblastic activities in both groups. However, at the 20th day, osteoblastic activity was significantly higher in the experimental group. Serum TAC values were also significantly higher in the experimental group at the 30th day. At necropsy, histopathologic examination revealed statistically significantly higher scores in the experimental group.

Conclusion

The results of this study show that alpha-tocopherol has beneficial effects on new bone formation during distraction osteogenesis.

Effects of propolis on fracture healing: an experimental study

Propolis is a substance of honeybee origin with known antioxidant effects. The purpose of this study was to examine the effects of propolis on fracture healing and the antioxidant system in an experimental setting. Thirty-two rats that underwent experimental femur fracture and then fixation were randomly allocated in one of four groups: two control groups (Control-3w and Control-6w) and two treatment groups (Propolis-3w and Propolis-6w). Treatment groups received propolis until killing (at 3 or 6 weeks). X-ray, histological, bone mineral density measurement findings and endogenous antioxidant levels were examined. The bone mineral density was higher, radiological and histological evaluation scores were better, and superoxide dismutase, total glutathione and myeloperoxidase levels were lower among the rats that received oral propolis treatment compared with the controls. In addition, bone mineral density and histological assessment scores showed time-dependent improvement in the treatment group. In conclusion, the findings of this study suggest that propolis has some time-dependent beneficial effects on fracture healing.

Stimulation of Bone Formation by Dietary Boron in an Orthopedically Expanded Suture in Rabbits

Objective: To evaluate the effects of dietary boron on bone regeneration in rabbits in response to expansion of the midpalatal suture during different retention periods.

Materials and Methods: Twenty-eight 12-week-old New Zealand white male rabbits were separated into four equal groups: group 1 (B+10) and group 2 (B−10) had retention periods of 10 days with or without boron intake, respectively. Group 3 (B+20, with boron) and group 4 (B−20, without boron) were retained for 20 days. All groups had a 5-day expansion period. For both B+ groups, boron was prepared in distilled water and given to the rabbits during their (1) nursery phase (40 days), (2) expansion phase, and (3) retention period at a dosage of 3 mg/kg daily by oral gavage. Bone regeneration in the midpalatal suture was evaluated by a bone histomorphometric method, and the mineralized area (Md.Ar), fibrosis area (Fb.Ar), mineralized area/fibrosis area (Md.Ar/Fb.Ar), bone area (B.Ar) and osteoblast number (N.Ob) parameters were evaluated.

Results: Statistical analysis showed significant differences between groups for all investigated measurements. Md.Ar (P &lt; .01), Md.Ar/Fb.Ar (P &lt; .001), B.Ar (P &lt; .01), and N.Ob (P &lt; .01) parameters were increased and Fb.Ar (P &lt; .01) was decreased in groups B+10 and B+20. No significant differences were observed during an additional 10-day retention period in all groups (P &lt; .05).

Conclusions: Boron has a positive effect on the early phase of bone regeneration of the midpalatal suture in response to expansion and may be beneficial in routine maxillary expansion procedures.

Scavenger receptor of class B expressed by osteoblastic cells are implicated in the uptake of cholesteryl ester and estradiol from LDL and HDL3

Lipoproteins transport many vitamins and hormones that have been shown to be necessary for bone formation. However, the metabolism of LDL and HDL3 by bone-forming osteoblastic cells remains unknown. Here we report that osteoblastic cells express scavenger receptors of class B that are implicated in the uptake of cholesterol and estradiol from LDL and HDL3.

INTRODUCTION

The bone tissue is continuously remodeled, and its integrity requires a balance between osteoclastic bone resorption and osteoblastic bone formation. Recent studies have reported the importance of triglyceride-rich lipoproteins for the delivery of lipophilic vitamins necessary for normal bone metabolism. However, the ability of osteoblastic cells to process low- and high-density lipoproteins (LDL and HDL3) and the receptors involved remain unknown.

MATERIALS AND METHODS

Binding, competition, degradation, and selective uptake assays with LDL and HDL3 radiolabeled in their protein and lipid moieties or with [3H]estradiol were conducted on human osteoblasts (MG-63 cell line and primary cultures of human osteoblasts [hOB cells]) and on mouse osteoblasts (MC3T3-E1 cell line and primary cultures of murine osteoblasts [mOB cells]). The expression of scavenger receptors (SRs) by osteoblastic cells was determined by RT-PCR and Western immunoblotting, and cellular localization was assessed by sucrose gradient fractionation.

RESULTS

Osteoblastic cells were able to bind, internalize, and degrade HDL3 and LDL and are capable of selectively taking up cholesteryl esters (CEs) from these lipoproteins. Also, we provide evidence that osteoblastic cells express SR-BI, SR-BII, and CD36 (SR-Bs receptors) and that these receptors are localized in membrane lipid rafts or caveolin-rich membranes. The selective uptake of CE from LDL and HDL3 by osteoblastic cells was strongly inhibited by the known SR-B ligand oxidized LDL, indicating that SR-B receptors are responsible for the selective uptake. Finally, estradiol carried by LDL and HDL3 was selectively transferred to the osteoblastic cells also through SR-B receptors.

CONCLUSIONS

Overall, our results suggest a novel mechanism for the routing of cholesterol and estradiol to osteoblasts involving the metabolism of LDL and HDL3 by SR-B receptors.

Fracture healing in the elderly patient

Clinical experience gives rise to the impression that there are differences in fracture healing in different age groups. It is evident that fractures heal more efficiently in children than in adults. However, minimal objective knowledge exists to evaluate this assumption. Temporal, spatial, and cellular quantitative and qualitative interrelationships, as well as signaling molecules and extracellular matrix have not been comprehensively and adequately elucidated for fracture healing in the geriatric skeleton. The biological basis of fracture healing will provide a context for revealing the pathophysiology of delayed or even impaired bone regeneration in the elderly. We will summarize experimental studies on age-related changes at the cellular and molecular level that will add to the pathophysiological understanding of the compromised bone regeneration capacity believed to exist in the elderly patient. We will suggest why this understanding would be useful for therapeutics focused on bone regeneration, in particular fracture healing at an advanced age.

Does long-term ischemia affect the oxidant status during fracture healing?

INTRODUCTION

The influence of transient circulatory arrest on oxidant status during the healing of a tibial fracture was investigated in rats by the use of a hindlimb tourniquet technique.

MATERIALS AND METHODS

One of the most reliable indicators for cytological damage is lipid peroxidation, which can be demonstrated by malondialdehyde (MDA) levels. Fifty-eight Wistar rats were used in this study. To determine the basal MDA levels of bone, 10 rats not exposed to ischemia were killed by an overdose of ether. The remaining 48 rats were randomly divided into two groups (control and ischemia). The control and ischemia groups were then randomly divided into 4 groups of 6 rats each. In 48 rats, the left tibia was fractured and fixed intramedullarly. In the ischemic group, complete acute transient ischemia for 4.5 h was imposed after the fracture. In the control group, no other intervention except the fracture was done. Rats from the control and ischemic groups were killed on days 3, 7, 14, and 28, and MDA levels were determined in tibial bone and callus tissue. The MDA levels of the control and ischemic groups were compared with basal MDA levels in the bone of 10 rats.

RESULTS

There was an apparent difference between the basal and control group MDA levels on days 3 and 7 (p < 0.01), between the basal and ischemic group MDA levels on days 3, 7, and 14 (p < 0.01). In addition, the ischemic group showed a statistically significant increase in MDA levels on days 3, 7 and 14 compared with the control group (p < 0.01).

CONCLUSION

We conclude that complete acute transient ischemia affects the oxidant status during fracture healing. This effect especially occurs during the ischemic period, inflammation, and callus formation of fracture healing.