Mature Bone Structure Research Articles

Comparison of the effects of fluoxetine and venlafaxine on bone healing in a rat calvarial defect model

ObjectiveThe purpose of this study was to compare the effects of the selective serotonin reuptake inhibitor (SSRI) fluoxetine and the serotonin-norepinephrine reuptake inhibitor (SNRI) venlafaxine on bone defect healing. Materials and MethodsWistar rats were randomly divided into three groups of eight animals each. The first received 0.1 ml/kg sterile saline solution, the second 5 mg/kg fluoxetine, and the third 5 mg/kg venlafaxine, daily by gastric gavage over 7 weeks. At week 3 of drug therapy, 5-mm diameter calvarial defects were created in the parietal bone of all of the animals. All rats were euthanized four weeks after surgery, micro-CT analysis and histomorphometric analysis were carried out to evaluate the following parameters: Bone volume fraction (BV/TV), bone surface (BS), bone surface density (BS/BV; bone surface/bone volume, 1/mm), trabecular number (Tb. N), trabecular thickness (Tb. Th), areas of new bone structure (positive areas), areas of mature bone structure (negative areas). ResultsMicro-CT analysis showed the presence of similar levels of bone formation within the defect site in all three groups (p>0.05). Histomorphometric analysis revealed the presence of bone-forming cells at the defect periphery, with less activity indicating bone formation at the center. No statistically significant difference was observed between the groups (p>0.05). ConclusionBased on the findings of this study, it can be said that the use of both antidepressants hasn't any effect on bone defect healing.

Proximal femoral growth plate mechanical behavior: Comparison between different developmental stages

In long bones the growth plate is a cartilaginous structure located between the epiphysis and the diaphysis. This structure regulates longitudinal growth and helps determine the structure of mature bone through the process of endochondral ossification. During human growth the femur's proximal growth plate experiences changes in its morphology that may be related to its mechanical environment. Thus, in order to test this hypothesis from a computational perspective, a finite element analysis on a proximal femur was performed on which we modeled different physeal geometries corresponding to the shapes acquired for this structure in a child between the ages of five to eleven. Results show augmented Von Mises stress values with increasing irregularities in physeal geometry, whereas displacement decreased with increased irregularities in the growth plate's morphology. Such observations suggest that growth plate's shape changes follows a possible mechanical adaptation on imposed loads to sustain a person's increasing body mass during growth.

Investigation of ossification in the posterior longitudinal ligament using micro-focus X-ray CT scanning and histological examination.

BackgroundOssification in the posterior longitudinal ligament (PLL) correlates with changes of enthesis during the early stages of development, but this issue remains controversial, as little is known regarding the details of this process. The aim of the present study was to elucidate part of the ossification mechanism. Thus, in the present study, we observed and evaluated minute ossifications in the PLL that did not exhibit symptoms of ossification of the posterior longitudinal ligament (OPLL).MethodsThe subjects in the present study were derived from serial autopsy cases from January 2009 to December 2013 at Toho University Omori Medical Center, Japan. Minute ossifications in the PLL from autopsy subjects without any history of OPLL were screened as high-density areas using micro-focus X-ray CT, and the foci were histologically examined. Subsequently, we conducted both micro-focus X-ray CT image analysis and histological examination, and evaluated the correlation between these findings and putative predictive factors reported in previous studies.ResultsA total of 103 individuals among the 267 subjects involved in the present study were analyzed within the study period. There were no cases involving OPLL identification prior to death, and no subjects presented with neurological symptoms of myelopathy. The incidence of cases involving high-density areas greater than 0.1 mm2 in the PLL was 46.6 %, half of which revealed mature bone structures inside this area. Thus, the high-density areas comprised three types: a continuous posterior-annular fibrosus type (23 cases), an isolated posterior-annular fibrosus type (11 cases), and a posterior-vertebral type (29 cases). However, a positive correlation was observed between the proportion of high-density areas, age (Pearson r = 0.265, p < 0.01), and HbA1c (Pearson r = 0.294, p < 0.01). Histological examination confirmed that these high-density areas involved calcification with or without mature bone formation.ConclusionsWe evaluated minute foci of calcification with and without ossification in the PLL from 103 cadavers, generating the following observations:Minute calcification foci greater than 0.1 mm2 were observed in the PLL of 48 cases (46.6 %), half of which revealed mature bone structures inside this area (23.3 %).The proportion of minute calcification foci observed in the present study was correlated with age and glucose tolerance, suggesting changes in the OPLL in the early stage.Three different mechanisms of ossification were suggested: The two structures developed behind the disc might reflect the elongation of enthesis or rupture of annular fibrosus, while the remaining structure developed behind the vertebral body might reflect a dystrophic calcification-based bony metaplasia sequence.

Maxillary Sinus Floor Elevation Using BMP-2 and Nell-1 Gene-Modified Bone Marrow Stromal Cells and TCP in Rabbits

This study evaluated the synergistic osteogenic effect of bone morphogenetic protein-2 (BMP-2) and Nel-like molecule-1 (Nell-1) genes in a rabbit maxillary sinus floor elevation model. Bone marrow stromal cells (bMSCs) were cultured and transduced with AdEGFP, AdNell-1, AdBMP-2, or AdNell-1+AdBMP-2 overexpression virus. These gene-modified autologous bMSCs were then combined with a β-tricalcium phosphate (β-TCP) granule scaffold and used to elevate the maxillary sinus floor in rabbits. bMSCs cotransduced with AdNell-1+AdBMP-2 demonstrated a synergistic effect on osteogenic differentiation as detected by real-time PCR analysis on markers of runt-related transcription factor-2, osteocalcin, collagen type 1, alkaline phosphatase activity, and calcium deposits in vitro. As for maxillary sinus floor elevation in a rabbit model in vivo, AdNell-1+AdBMP-2 gene-transduced autologeous bMSCs/β-TCP complex had the largest bone area and most mature bone structure among the groups, as detected by HE staining and immunohistochemistry at weeks 2 and 8 after implantation. Our data suggested that the BMP-2 and Nell-1 genes possessed a synergistic effect on osteogenic differentiation of bMSCs, while bMSCs modified with the BMP-2 and Nell-1 genes could promote new bone formation and maturation in the rabbit maxillary sinus model.

Trifocal Biplanar Distraction-Compression Osteosynthesis

Surgical treatment of calvarial defects and deformities has some drawbacks such as donor site morbidity or use of allogenic materials. In this experimental study, we presented a three-dimensional reconstruction of cranial defects by using trifocal biplanar distraction-compression osteosynthesis (TBDCO).Eight sheep with a mean age of 2 years were divided into 2 groups as the control (n = 3) and distraction groups (n = 5). All the animals were operated on under general anesthesia, and 80 x 50-mm full-thickness calvarial defects were created. In the control group, no treatment was performed. In the distraction group, TBDCO was performed with a custom-made distraction device with 2 transport segments. After 5 days of latency period, the anterior transport segment was distracted to a posterior and superior direction (0.7 and 0.3 mm, respectively) and the posterior transport segment was distracted obliquely to an anterior and superior direction (0.7 and 0.3 mm, respectively) with a resulting total vectorial movement of 0.75 mm/d. Active distraction was approximately 29 days, and the consolidation period was 60 days.No major complications were seen during the whole procedure. In the control group, the bone defects remained unhealed. In the distraction group, defects healed and the reconstructed calvarium was dome shaped. Preoperative and postoperative cranial volume measurements of the distraction group animals revealed an increase in cranial volume (P < 0.05). Histologic evaluation showed inductive bone regeneration and mature bone structure development within the distraction zone. Trifocal biplanar distraction-compression osteosynthesis is an effective and safe technique for three-dimensional closure of the cranial defects. In clinical practice, it could provide several advantages over currently available reconstructive procedures.

Calvarial Reshaping Using Bifocal Bidirectional Transport Distraction Osteogenesis

The aim of this study is to assess 3-dimensional reconstruction of cranial defects by use of bifocal bidirectional transport distraction osteogenesis (BBTDO). This study was performed on 8 sheep, divided into a control group (n = 3) and treatment group (n = 5). Full-thickness cranial defects (50 x 40 mm) were created on calvaria. In the control group only the skin was closed. In the treatment group BBTDO was performed. Distraction was performed with a custom-made distraction device with a transport segment of 40 x 20 mm. After a 5-day period of latency, distraction was applied to the transport segment. During the first 20 days of distraction, the transport segment was distracted 1 mm in the forward direction and 0.5 mm in the upward direction. After the next 20 days of distraction, the transport segment was distracted 1 mm forward and 0.5 downward. After a total of 40 days' distraction, a 30-day consolidation period was applied. Macroscopic, radiologic (computed tomography with volume measurements), and histologic evaluations were done. No major complications were seen during the whole study period. In the control group the bone defects remained unhealed at the end of the study period. The same-sized defects in the treatment group healed with a convexity like the calvaria. Preoperative and postoperative cranial volume measurements of the treatment group animals showed an increase in cranial volume (P < .05). Histologic evaluation showed inductive bone regeneration and mature bone structure development within the distraction zone. The BBTDO is an effective and safe technique for 3-dimensional closure of cranial defects.

Maxillary sinus floor elevation using a tissue‐engineered bone complex with β‐TCP and BMP‐2 gene‐modified bMSCs in rabbits

To study the effects of maxillary sinus floor elevation by a tissue-engineered bone complex with beta tricalcium phosphate (beta-TCP) and bone morphogenetic protein-2 (BMP-2) gene-modified bone marrow stromal cells (bMSCs) in rabbits. bMSCs derived from New Zealand rabbit bone marrow were cultured and transduced with the adenovirus with BMP-2 (AdBMP-2), adenovirus with enhanced green fluorescent protein gene (AdEGFP) in vitro. Gene transfer efficiency was detected by EGFP expression. These gene-modified autologous bMSCs were then combined with a beta-TCP granule scaffold at a concentration of 2 x 10(7) cells/ml and used to elevate the maxillary sinus floor in rabbits. Twenty rabbits were randomly allocated into groups and sacrificed at weeks 2 and 8. For each time point, 20 maxillary sinus floor elevation surgeries were made bilaterally in 10 rabbits for the following groups (n=5 per group): group A (beta-TCP alone), group B (untransduced bMSCs/beta-TCP), group C (AdEGFP-bMSCs/beta-TCP), and group D (AdBMP-2-bMSCs/beta-TCP). All samples were evaluated by histology and histomorphometric analysis. The fate of implanted bMSCs was traced initially by a confocol fluorescent microscope in the AdEGFP group. Gene transfer efficiency reached up to 60-80% with 50 PFU/cell transduction as demonstrated by fluorescent microscopic analysis in the AdEGFP group. The augmented maxillary sinus height was maintained for the four groups till 8 weeks post-surgery, while new bone area increased over the time. At week 2, bone areas in groups B-D were significantly larger than those in group A, while at week 8, in group D, the BMP-2 gene-enhanced tissue-engineered bone had the largest bone area among the groups (P<0.05, ANOVA). In that group, a mature bone structure was detected in the center of the elevated space. Under a confocal microscope, green fluorescence in newly formed bone was observed for the EGFP group, which suggested that those implanted bMSCs might have contributed to the new bone formation. bMSCs modified with the AdBMP-2 gene can promote new bone formation and maturation in the rabbit maxillary sinus. BMP-2 regional gene therapy and a tissue engineering technique could be effectively used in maxillary sinus elevation and bone regeneration.

Novel maxillary reconstruction with ectopic bone formation by GMP adipose stem cells

Microvascular reconstruction is the state-of-the-art in many fields of defect surgery today. Currently, reconstruction of large bony defects involves harvesting of autologous bone causing donor site morbidity and risk of infection. Specifically, utilizing autologous adipose stem cells (autoASCs), large quantities of cells can be retrieved for cell therapy applications and the risk of tissue rejection is diminished. The authors describe the first case report of a microvascular custom-made ectopic bone flap employing good manufacturing practice (GMP) level ASCs. The patient underwent a hemimaxillectomy due to a large keratocyst. After 36 months of follow-up, the defect was reconstructed with a microvascular flap using autoASCs, beta-tricalcium phosphate and bone morphogenetic protein-2. ASCs were isolated and expanded in clean room facilities according to GMP standards and were characterized in vitro. After 8 months of follow-up, the flap had developed mature bone structures and vasculature and was transplanted into the defect area. Postoperative healing has been uneventful, and further rehabilitation with dental implants has been started. The in vitro characterization demonstrated multipotentiality and mesenchymal stem cell characteristics in ASCs. This is the first clinical case where ectopic bone was produced using autoASCs in microvascular reconstruction surgery and it will pave way for new clinical trials in the field.

Ultrastructure of Bone Mineralization and Osseointegration with Hydroxyapatite-Coated Bone Implants in Vivo

Abstract The need to optimize adhesion between the femoral stem and surrounding tissue has led to the development of plasma-sprayed HA (PSHA) coatings as attachment facilitators for hip prostheses. The mechanisms underlying this facilitation are incompletely understood, and the long-term efficacy of HA coatings in maintaining bonding to bone remains largely unexplored. in this study, two in vivo models—canine and human—were employed for study by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to elucidate the sequence of early bone mineralization and the longer term fate of HA coatings. High-resolution SEM and TEM of whole bone and anorganic bone were employed to establish the structure of mature bone for comparison. Whole and Anorganic Bone.Anorganic bone derived from bovine trabecular bone was examined in low-voltage field-emission SEM(LV-FESEM) and high-resolution TEM to establish the morphology of the mineral component of bone [1,2]. Trabeculae were seen to comprise oriented fiber bundles (Fig. 1), each fiber comprising an array of oriented apatite platelets (Fig. 2) arranged like a sheared stack of dominoes with approximately the 64-nm stagger of collagen hole zones.

Effects of high-fat diet on mature bone mineral content, structure, and mechanical properties.

Diets with a high saturated fat content can produce deleterious effects on the absorption of dietary calcium and consequently an adverse effect on bone mineralization in growing animals. Hence dietary fat may have long-term consequences for skeletal health and skeletal pathologies such as osteoporosis. Whether a diet high in saturated fat has similar negative effects on adult bone, however, remains unresolved. Thus, we investigated effects of a high-fat diet on mature bone structure and mechanics. Adult (40-week-old) roosters were maintained for 20 weeks on either a diet high in saturated fat (HF) or a low-fat (LF) diet. Cortical bone samples (tarsometatarsus) were tested mechanically in three-point bending, and cancellous bone cores from the femoral condyles and tibial plateau (four sites per knee) were tested mechanically in compression. Cortical bone cross-sectional areal data were also compared among the groups, and bone mineral content (BMC) was determined (by ashing) for both cortical bone and cancellous bone samples. There were no significant high-fat diet effects on mature cortical bone mechanical properties, geometric structure, or mineral content. Diet, however, did affect cancellous bone composition. For example, LF cancellous BMC was significantly greater than HF. Mechanical properties of the cancellous bone showed similar trends such that LF cancellous bone strength was consistently greater than HF. The potential for adverse effects of a HF diet on intestinal calcium absorption in the mature animal may be more apparent in cancellous bone, with its faster rate of turnover, than in cortical bone. Changes in cancellous bone structure and mechanical properties, related to dietary saturated fats, may have implications for understanding the role of nutrition in skeletal health and prevention of pathological bone loss (osteoporosis).

The natural history of pulmonary ossification

Introduction: Pulmonary ossification (PO) is a rare pathologic finding, defined as a widespread heterotopic bone formation within the lungs. PO occurs in two forms. The first form is the nodular circumscribed type; the second form is the racemose or branching type. Males are more often affected than females. PO occurs more commonly in older patients, in the sixth decade. The most common site of occurrence is the basal lobes. Material and Methods: Autopsy of a 65 year old man revealed advanced hepatic cirrhosis. Death resulted from fatal hemorrhage from ruptured esophageal varices. In addition we found widespread PO in both lungs. About 100 tissue samples were taken from the lungs, processed in a histokinetic tissue processor, impregnated with paraplast, and cut into 5 μ sections. The sections were stained as follows: Hematoxylin and Eosin, Verhoef's elastic stain, van Gieson Trichrome stain, Gordon and Sweet's Silver impregnation, Prussian Blue reaction, PAS reaction, Celestin blue, Hematoxylin, Ethanolic-Saffron, Alcian Green (pH 2.8, CHESA) stain reaction. Results: The formation and growth of these bony structures occur as a type of osseous metaplasia of the connective tissue. Mesenchymal cells proliferate in the interstitial tissue and produce osteoid. Insofar as formation and growth take place in the absence of blood vessels, immature (woven) bone is formed. This is true for the nodular circumscribed type of PO. In the branching type of PO blood vessel proliferation is often observed, which results in the formation of mature (lamellar) bone. These mature bone structures often enclose an endosteum-lined marrow cavity which contains fat or red marrow. Finally, we also observed peculiar desmoid-like connective tissue proliferation, which occasionally showed transformation into bone. Discussion: PO occurs in two forms. The nodular cirbumscribed type is composed of osseous and osteoid material without marrow elements. It is usually deposited within the lung septa. The second form is the racemose type. It consists of branching spicules of bone in the alveolar septa. This osseous tissue contains mostly marrow elements. As for the pathogenesis of PO, we believe in heterotopic bone formation resulting from connective tissue proliferation which subsequently undergoes osseous metaplasia. In addition to PO, we found peculiar desmoid-like connective tissue proliferation in the lungs, which occasionally showed transformation into bone. PO appears to be functionally unimportant.