Quantitative bone single photon emission computed tomography analysis of the effects of duration of bisphosphonate administration on the parietal bone.

Effects of long-term bisphosphonate (BP) administration on the metabolism of healthy bone and the concomitant changes in imaging are unclear. Hence, we aimed to retrospectively investigate the effects of long-term BP administration on the intact parietal bone using the standardised uptake value (SUV) derived from single photon emission computed tomography (SPECT). We enrolled 29 patients who had odontogenic infection, osteoporosis, bone metastasis cancer, or rheumatoid arthritis, and classified them into BP-naïve: A (14 patients) and BP-treated: B, < 4 years (7 patients) and C, ≥ 4 years (8 patients) groups. We measured the maximum bilateral SUV (SUVmax) of the parietal bone using quantitative bone SPECT software. There were significant differences in the duration of BP administration and SUVmax of the parietal bone among the diseases (P < 0.0001 and P = 0.0086, respectively). There was a positive correlation between the duration of BP administration and SUVmax of the parietal bone (rs = 0.65, P = 0.0002). The SUVmax was significantly different between A and B (P = 0.02) and between A and C (P = 0.0024) groups. This is the first report on the correlation between long-term BP administration and the SUVmax of the parietal bone using the quantitative bone SPECT analysis.

Effect of Morphogenetic Protein BMP-2 on X-Ray Density of Bone Defect in the Experiment.

In experiments on Wistar rats, a simulated defect in the flat bones of the skull was filled with a collagen sponge of animal origin impregnated with BMP-2 or pure sponge; in control rats, the defect was left open. During follow-up, X-ray density of the collagen sponge in the experimental groups differed significantly. The results attest to the absence of spontaneous remodeling of the bone tissue under conditions modeled focal defect. Moreover, stimulation of reparative processes by the collagen matrix did not lead to positive dynamics. Saturation of the collagen sponge with BMP-2 in a concentration of 0.05 mg/ml allowed increasing Xray density of the bone starting from week 4.

Ketamine decreases cell viability of bone explants and impairs bone healing in rats.

BACKGROUND: Ketamine is a widely used anesthetic in experimental medicine. We have also used ketamine for surgical interventions and imaging in rats and found significantly impaired ossification between identically performed experiments, which only differed in the number of anesthetic events. In order to investigate this phenomenon, we estimated the absorbed ionizing radiation and also studied whether ketamine administration has disadvantageous effect on bone cell viability. METHODS: Spongious bone chips and parietal bone disks were harvested from rats. Explants were incubated in stem cell media containing 0.02, 0.2 and 2 mM ketamine. After 3 days of incubation, tetrazolium-based spectrophotometric assay was performed to measure cell viability. Size-specific dose estimation was used to calculate ionizing radiation of computed tomography imaging. RESULTS: We found that ketamine supplementation with 0.2 mM slightly decreased cell viability, while 2 mM caused significant reduction both in the spongious and cortical explants. The cumulative ionizing radiation was found to be negligible compared to irradiation dosages used to impair ossification. CONCLUSIONS: We conclude that multiple ketamine administration was responsible for the diminished regenerative potential of bone tissue in the present experimental setup. For this reason, we suggest that ketamine anesthesia should be avoided in studies investigating bone regeneration.

Evaluating the bioactivity of a hydroxyapatite-incorporated polyetheretherketone biocomposite.

BACKGROUND: Polyetheretherketone (PEEK) exhibits stable chemical properties, excellent biocompatibility, and rational mechanical properties that are similar to those of human cortical bone, but the lack of bioactivity impedes its clinical application. METHODS: In this study, hydroxyapatite (HA) was incorporated into PEEK to fabricate HA/PEEK biocomposite using a compounding and injection-molding technique. The tensile properties of the prepared HA/PEEK composites (HA content from 0 to 40 wt%) were tested to choose an optimal HA content. To evaluate the bioactivity of the composite, the cell attachment, proliferation, spreading and alkaline phosphatase (ALP) activity of MC3T3-E1 cells, and apatite formation after immersion in simulated body fluid (SBF), and osseointegration in a rabbit cranial defect model were investigated. The results were compared to those from ultra-high molecular weight polyethylene (UHMWPE) and pure PEEK. RESULTS: By evaluating the tensile properties and elastic moduli of PEEK composite samples/PEEK composites with different HA contents, the 30 wt% HA/PEEK composite was chosen for use in the subsequent tests. The results of the cell tests demonstrated that PEEK composite samples/PEEK composite exhibited better cell attachment, proliferation, spreading, and higher ALP activity than those of UHMWPE and pure PEEK. Apatite islands formed on the HA/PEEK composite after immersion in SBF for 7 days and grew continuously with longer time periods. Animal tests indicated that bone contact and new bone formation around the HA/PEEK composite were more obvious than those around UHMWPE and pure PEEK. CONCLUSIONS: The HA/PEEK biocomposite created by a compounding and injection-molding technique exhibited enhanced osteogenesis and could be used as a candidate of orthopedic implants.

Calcium-containing scaffolds induce bone regeneration by regulating mesenchymal stem cell differentiation and migration.

BACKGROUND: Osteoinduction and subsequent bone formation rely on efficient mesenchymal stem cell (MSC) recruitment. It is also known that migration is induced by gradients of growth factors and cytokines. Degradation of Ca2+-containing biomaterials mimics the bone remodeling compartment producing a localized calcium-rich osteoinductive microenvironment. The aim of our study was to determine the effect of calcium sulfate (CaSO4) on MSC migration. In addition, to evaluate the influence of CaSO4 on MSC differentiation and the potential molecular mechanisms involved. METHODS: A circular calvarial bone defect (5 mm diameter) was created in the parietal bone of 35 Balb-C mice. We prepared and implanted a cell-free agarose/gelatin scaffold alone or in combination with different CaSO4 concentrations into the bone defects. After 7 weeks, we determined the new bone regenerated by micro-CT and histological analysis. In vitro, we evaluated the CaSO4 effects on MSC migration by both wound healing and agarose spot assays. Osteoblastic gene expression after BMP-2 and CaSO4 treatment was also evaluated by qPCR. RESULTS: CaSO4 increased MSC migration and bone formation in a concentration-dependent manner. Micro-CT analysis showed that the addition of CaSO4 significantly enhanced bone regeneration compared to the scaffold alone. The histological evaluation confirmed an increased number of endogenous cells recruited into the cell-free CaSO4-containing scaffolds. Furthermore, MSC migration in vitro and active AKT levels were attenuated when CaSO4 and BMP-2 were in combination. Addition of LY294002 and Wortmannin abrogated the CaSO4 effects on MSC migration. CONCLUSIONS: Specific CaSO4 concentrations induce bone regeneration of calvarial defects in part by acting on the host's undifferentiated MSCs and promoting their migration. Progenitor cell recruitment is followed by a gradual increment in osteoblast gene expression. Moreover, CaSO4 regulates BMP-2-induced MSC migration by differentially activating the PI3K/AKT pathway. Altogether, these results suggest that CaSO4 scaffolds could have potential applications for bone regeneration.

Reversible Alopecia with Localized Scalp Necrosis After Accidental Embolization of the Parietal Artery with Hyaluronic Acid.

Hyaluronic acid (HA) filler injection is widely used for soft-tissue augmentation. Complications associated with HA filling are not uncommon; however, HA-induced alopecia is a rarely reported complication that could result in severe secondary psychological trauma. The etiology, clinical traits, treatment strategies, outcomes, and possible reversibility of HA-induced alopecia have not been characterized. Here, we report a case in which bilateral temple injections of 6.5 mL of HA led to persistent pain over the left scalp for several days. Although the pain was relieved at day 9 after 600 U of hyaluronidase were injected in the left temple, the patient developed localized alopecia at the left temporoparietal region with central skin necrosis at day 15. After topical applications of recombinant bovine basic fibroblast growth factor gel and 2% minoxidil spay, the necrotic skin wound was healed at day 42. Hair regrowth and normal hair density were restored at day 74. Analyses of Doppler ultrasound examinations and histopathology of the skin biopsy suggested that mild ischemia of the left temporoparietal region led to reversible alopecia, while the permanent hair loss in the left parietal area was associated with severe skin ischemia. Therefore, the key to treatment would be to focus on the effective correction of severe ischemia-induced skin necrosis to prevent permanent hair loss. Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Starch-derived absorbable polysaccharide hemostat enhances bone healing via BMP-2 protein.

Surgical hemostasis is critical in reducing the likelihood of excessive bleeding and blood transfusion. In treating some cases, commonly used hemostatic agent showed limited efficacy and prolonged degradation and clearance, causing an inhibition of bone healing. Starch absorbable polysaccharide (SAPH) is a novel hemostatic agent made from a plant starch, which can be completely absorbed and achieve better hemostatic effects than many commonly used hemostatic agents. However, whether SAPH can induce a promotion of bone healing remains unknown. In this study, we used a model of rabbit parietal bone defect and a mouse osteoblast cell line MC3T3-E1 to evaluate the effects of SAPH on bone healing. We found that SAPH significantly decreased bone healing scores, reduced defective area of parietal bone, and increased the areas of bone trabeculae and cavitas medullaris. In addition, SAPH enhanced MC3T3-E1 osteoblasts proliferation, up-regulated the expressions of alkaline phosphatase (ALP) and osteocalcin and increased the level of bone morphogenetic protein 2 (BMP-2) in MC3T3-E1 osteoblasts. These SAPH-induced benefits in MC3T3-E1 osteoblasts were significantly abolished by the application of BMP-2-siRNA. These findings suggested that SAPH enhances bone healing, promotes the proliferation, differentiation and maturation of osteoblast by up-regulating BMP-2 expression in osteoblastic cells.

Effects of caffeic acid phenethyl ester on wound healing in calvarial defects.

OBJECTIVE: The aim of this study is to analyze histologically the effect of CAPE on bone healing of Critical Size Defect (CSD) in rat calvaria. STUDY DESIGN: Thirty-two 3-month-old male rats were used. The animals were randomly divided into four groups. Group A received isotonic saline solution, Group B received CAPE (50 mmol/kg) locally, Group C received CAPE (100 mmol/kg) locally and Group D received CAPE (10 mmol/kg/day i.p. for 28 days) systematically. A 5-mm diameter calvarial defect was created in the right side of the parietal bone without damaging the underlying dura mater. Twenty-eight days after the surgery, all the animals were sacrificed. The original defect area was removed from the animal's calvarium bone en bloc. Beginning at the center of the surgical defect, serial sections of 6 µm thick were cut longitudinally. The sections were stained with hematoxylin and eosin for analysis under a light microscope. The sections were analyzed for the presence of inflammatory infiltrate, connective tissue formation and new bone formation. Computer-assisted histomorphometic measurements were carried out with an automated image analysis system. RESULTS: The total new bone areas were significantly greater in group D than in all groups and group C was statistically insignificant from the other groups (p < 0.05). Group B had a greater, but not statistically significant (p > 0.05), amount of total regenerated bone area than the control group. CONCLUSION: The results indicate that 100 mmol/kg topical and 10 mmol/kg/day systemic application of CAPE increases bone healing, especially with systemic application.

Effect of rhBMP-2 dose on bone formation/maturation in a rat critical-size calvarial defect model.

BACKGROUND: Application of recombinant human bone morphogenetic protein-2 (rhBMP-2) has been associated with significant adverse events in craniofacial settings, including swelling and seroma formation. Recent work has demonstrated an inverse relationship between bone formation/maturation and rhBMP-2 dose, frequency/severity of adverse events increasing with rising dose. OBJECTIVE: The objective of this study was to determine the most effective dose for rhBMP-2 soak-loaded onto an absorbable collagen sponge (ACS) carrier for bone formation/maturation using an established defect model. METHODS: One hundred sixty-eight outbred male Sprague-Dawley rats, age 11-13 weeks, weight 325-375 g randomized into seven groups of 24 subdivided into groups of eight, were used to provide radiographic and light microscopy observations of bone formation/maturation and aberrant healing events at 2, 4 and 8 weeks following application of rhBMP-2/ACS into critical-size, ø8-mm, through-through, calvarial osteotomy defects for a dose of 1.25, 2.5, 5.0, 10.0 and 20.0 µg rhBMP-2/defect, or serve as ACS or sham-surgery controls. RESULTS: rhBMP-2 dosages ≥ 2.5 µg/defect showed histological defect closure >90% within 2 weeks, and complete resolution within 4 weeks. Adverse healing events including swelling, excessive bone formation or seroma formation could not be determined with certainty in this defect model. Notably ACS control sites showed complete defect closure at the 8-week healing interval. CONCLUSIONS: rhBMP-2/ACS accelerates local bone formation in the rat critical-size through-through calvarial defect model once reaching an osteoinductive dose threshold. This threshold may already be reached at a 1.25-/2.5-µg dose in this model. No further enhancement to bone formation/maturation may be observed adding rhBMP-2 above the 2.5-µg dose. The 1.25-20.0 µg dose range did not invoke appreciable aberrant healing events.

Modification of xenogeneic graft materials for improved release of P-15 peptides in a calvarium defect model.

Particulate bone augmentation is an established clinical alternative to regenerate bone. However, in regions of poor bone quality or previously infected sites, the clinical outcomes are more inconsistent. For that purpose, peptides have been added to particulate materials in an attempt to render them with antibacterial properties or to improve their osseoconductivity. For instance, competence-stimulating peptide (CSP) has been studied to decrease the division rate of Streptococcus mutans. Also, the addition of a specific short amino acid sequence peptide derived from type I collagen (P-15) to the bone substitutes has been introduced in an attempt to increase its osseoconductivity. The present study hypothesized that xenogeneic graft materials with and without CSP would present improved host-to-biomaterial response when used in combination with P-15. Particulate graft materials with and without P-15, OsteoGraf with CSP and OsteoGraf, were implanted in an 8-mm rabbit calvarial defect for 4 weeks, and thereafter, histological and histomorphometrical evaluation was performed. The results showed that both OsteoGraf and CSP groups with the addition of P-15 induced bone growth towards the center of the defect. Furthermore, the addition of CSP to Osteograf showed a tendency to increase its osteoconductivity when combined with P-15. The results of the current study suggested that P-15 had some impact on osteogenesis; however, the effect differed between different bone substitute materials. Further investigation is necessary to clarify its effectiveness when used in combination with bone substitutes.

Demineralization of the contacting surfaces in autologous onlay bone grafts improves bone formation and bone consolidation.

BACKGROUND: Autologous bone grafts are usually well consolidated after 4 to 5 months but can be incompletely interlocked with the native bone. This study investigated the effect of acid demineralization of the graft-bed interface on graft consolidation. METHODS: Onlay bone grafts were performed on the calvaria of 36 guinea pigs. Half of the animals had the graft-bed contacting surfaces demineralized with 50% citric acid (pH 1.0) for 3 minutes (test group). The other half received no demineralization (control group). The bone grafts were immobilized by a resorbable membrane glued to the recipient bed with cyanoacrylate. After 7, 30, and 90 days, specimens (n = 6) were obtained for light microscopy. Data from qualitative analysis and computerized histomorphometry were statistically processed at a significance level of 5%. RESULTS: Osteogenesis was not seen at the interface after 7 days. After 30 days, the test group showed 34.39% ± 13.4% of the interface area filled with mineralized tissue, compared to 17.14% ± 8.6% in the control group (P = 0.026). After 90 days, the mean percentages of mineralized tissue at the interface in the test and control specimens were 54.00% ± 11.23% and 38.65% ± 7.76% (P = 0.041), respectively. Within groups, a higher percentage of the area filled with mineralized tissue was seen at 90 days compared to 30 days (P = 0.004 for control and 0.041 for test). CONCLUSIONS: Demineralization of the contacting surfaces between autologous bone graft and bone bed improved new bone formation and bone consolidation. These data need to be confirmed in humans.

Enamel matrix derivative: protein components and osteoinductive properties.

BACKGROUND: Although enamel matrix derivative (EMD) has demonstrated the ability to promote angiogenesis and osteogenesis both in vitro and in vivo, the specific elements within the EMD compound responsible for these effects remain unknown. METHODS: Nine different protein pools from a commercially produced EMD were collected based on molecular weight. Six of these pools, along with the complete EMD unfractionated compound and positive and negative controls, were tested for their ability to induce bone formation in a calvarial induction assay. Immunocytochemistry of phosphorylated SMAD1/5/8 (phospho-SMAD), osterix, and vascular endothelial growth factor A (VEGF-A) was carried out at selected time points. Finally, proteomic analysis was completed to determine the specific protein-peptide content of the various osteoinductive pools. RESULTS: One of the lower-molecular-weight pools tested, pool 7, showed bone induction responses significantly greater than those of the other pools and the complete EMD compound and was concentration dependent. Dynamic bone formation rate analysis demonstrated that pool 7 was optimally active at the 5- to 10-µg concentration. It was demonstrated that EMD and pool 7 induced phospho-SMAD, osterix, and VEGF-A, which is indicative of increased bone morphogenetic protein (BMP) signaling. Proteomic composition analysis demonstrated that pool 7 had the highest concentration of the biologically active amelogenin-leucine-rich amelogenin peptide and ameloblastin 17-kDa peptides. CONCLUSIONS: These studies demonstrate that the low-molecular-weight protein pools (7 to 17 kDa) within EMD have greater osteoinductive potential than the commercially available complete EMD compound and that the mechanism of action, in part, is through increased BMP signaling and increased osterix and VEGF-A. With this information, selected components of EMD can now be formulated for optimal osteo- and angio-genesis.

Effects of laser and ozone therapies on bone healing in the calvarial defects.

This study aims to analyze the effect of the low-level laser therapy (LLLT) and ozone therapy on the bone healing of critical size defect (CSD) in rat calvaria. A total of 30 Wistar male rats were used. A 5-mm-diameter trephine bur was used to create CSD on the right side of the parietal bone of each rat calvarium. Once the bone was excised, a synthetic biphasic calcium phosphate graft material was implanted to all the bone defect sites. The animals were randomly divided into 3 groups as follows: the control group (n = 10), which received no LLLT or ozone therapy; the LLLT group (n = 10), which received only LLLT (120 seconds, 3 times a week for 2 weeks); and the ozone therapy group (n = 10) (120 seconds, 3 times a week for 2 weeks). After 1 month, all the rats were killed, and the sections were examined to evaluate the presence of inflammatory infiltrate, connective tissue, and new bone formation areas. Histomorphometric analyses showed that in the LLLT and ozone groups, the new bone areas were significantly higher than in the control group (P < 0.05). In the LLLT group, higher new bone areas were found than in the ozone group (P < 0.05). This study demonstrated that both ozone and laser therapies had a positive effect on bone formation in rat calvarial defect, compared with the control group; however, ozone therapy was more effective than LLLT (808 nm; 0.1 W; 4 J/cm(2); 0.028 cm(2), continuous wave mode).

Comparative study of fibrin and chemical synthetic sealant on dural regeneration and brain damage.

OBJECT: Several materials, such as polyethylene glycol (PEG) hydrogel and fibrin glue, have been used to seal dural incisions after brain and spinal surgeries. Although the use of PEG sealant is gaining popularity, it can be associated with postoperative cerebrospinal fluid leakage and infection. However, the reasons for this association are currently unknown. The present study aimed to investigate the effects of PEG sealant and fibrin glue on wound healing and brain damage in vivo. METHODS: Oval-shaped bone defects and dural defects were created bilaterally over the parietal lobes of 22 Japanese white rabbits. The dural defects were covered with 0.5 ml of fibrin glue on one side and 0.5 ml of PEG sealant on the other side. Dural regeneration and brain damage were investigated in each harvested brain and dura mater using light microscopy. RESULTS: Dural regeneration was more effective in the presence of fibrin glue than it was with PEG sealant (p = 0.014). Of the 22 rabbits, 11 showed thick (Grades ++ and +++) dural regeneration by 28 days postsurgery in the hemisphere where fibrin glue was used, whereas Grade +++ dural regeneration was not observed in the PEG hydrogel hemisphere, and only 4 rabbits showed Grade ++ regeneration. Abscess and granulation formation also tended to be more severe when PEG hydrogel sealant was used. No Grade ++ granulation/abscess formation was observed with fibrin glue, and Grade + was only observed in 13 of 22 rabbits. Conversely, with PEG hydrogel sealant, only 2 rabbits did not show granulation/abscess formation, and Grade +, ++, and +++ granulation/abscess formation was observed in 8, 7, and 5 rabbits, respectively. The extent of cortical damage was significantly greater in rabbits with abscesses and granulations, compared with rabbits without these lesions (p = 0.007). CONCLUSIONS: Dural regeneration tended to occur more rapidly with fibrin glue, whereas granulation was more likely with PEG hydrogel sealant, which led to postoperative complications. Histological analysis indicated that PEG hydrogel sealant inhibited the normal tissue healing process and that outcomes were improved by the use of fibrin glue.

Influence of acidic fibroblast growth factor on bone regeneration in experimental cranial defects using spongostan and Bio-Oss as protein carriers.

The objective of this study was to valuate 2 substances as potential carriers of fibroblast growth factor 1 (FGF-1) in a rat craniectomy model: gelatin sponge (Spongostan; Ferrosan A/S, Søborg, Denmark) and natural bone mineral (Bio-Oss; Geistlich Biomaterials, Wolhusen, Switzerland).Forty-eight adult male Sprague-Dawley rats were used. A 5-mm-diameter circular craniectomy was performed in the left parietal bone. Animals were divided into 6 experimental groups of 8 rats, each group receiving a different treatment: control (no substance added), Spongostan, Bio-Oss, FGF, FGF + Spongostan, and FGF + Bio-Oss. Animals were killed 12 weeks after surgery.Descriptive histology and stereology were used, the latter to measure the volumes of regenerated bone and Bio-Oss remaining in the defect. Analysis of variance was used to determine differences in bone regeneration between groups, and Mann-Whitney U test was used to compare the volume of remaining Bio-Oss particles.Histologically, the control defects behaved like critical size defects, showing incomplete bone regeneration. Only the FGF + Spongostan group achieved nearly complete bone regeneration. Bio-Oss particles seemed to reduce centripetal bone regeneration. Spongostan by itself did not interfere with spontaneous bone healing.Stereologic measurements of the volume of new bone growth, measured in cubic millimeter, were as follows: control group, 3.86 ± 1.03; Bio-Oss, 2.26 ± 1.06; Spongostan, 3.00 ± 0.81; FGF, 3.99 ± 1.85; FGF + Bio-Oss, 3.02 ± 1.88; and FGF + Spongostan, 8.93 ± 1.28. Analysis of variance showed a statistically significant difference between the FGF + Spongostan group and the other groups (P < 0.001). Comparison among the other groups did not show significant differences.Fibroblast growth factor 1 with a Spongostan carrier has shown great efficacy for bone regeneration in cranial critical size defects in rats. Bio-Oss did not produce a regenerative effect, either alone or with FGF-1.

Isotretinoin effect on the repair of bone defects - a study in rat calvaria.

BACKGROUND: Isotretinoin is a vitamin A derivative, indicated for the treatment of patients with severe acne, which shows several side effects on bone metabolism. OBJECTIVE: This study analyzed the process of bone repair in rats receiving 7.5 mg/kg/day of oral isotretinoin. METHODS: Thirty-three male albino Wistar rats, at approximately 60 days of age, were randomly assigned to control (n = 15) and experimental (n = 18) groups. Only the experimental group underwent oral isotretinoin therapy. In both groups, a 2-mm cavity was established in the calvarium of each animal. The animals were euthanize 21, 28 and 90 days postoperatively. The parietal bone was removed and the surgical specimens underwent histological examination. Computed histomorphometry allowed the measurement of the total area of bone defects and the proportion of newly formed bone at the different observation time points. RESULTS: In the experimental group, the results, expressed as mean percentage of newly formed bone, were: 25.37% (±9.14) at day 21; 41.78% (±7.00) at day 28; and 57.51% (±11.62) at day 90. In the control group, the results were: 17.10% (±9.23) at day 21; 34.42% (±7.70) at day 28; and 48.49% (±16.40) at day 90. CONCLUSION: These results enabled us to conclude that isotretinoin promoted acceleration in the process of new bone formation in rat calvaria, although this increase was not statistically significant.

Effects of mesenchymal stem cells in critical size bone defect.

BACKGROUND AND OBJECTIVES: The aim of this study was to compare culture-expanded, bone marrow-derived mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) loaded to biphasic calcium phosphate (BCP) bone ceramic in the repair of rat calvarial bone. MATERIALS AND METHODS: Critical-size (7 mm dia.) calvarial defects were prepared in the frontal-parietal bones of 90 adult female Sprague-Dawley rats. Rats were randomly divided into 5 groups, according to defect filling, as follows: Group I (n = 21), BCP; Group II (n = 21), BCP+PRP; Group III (n = 21), BCP+MSC; Group IV (n = 21), BCP+PRP+MSC; Group V (n = 6) (control), no treatment. Animals were sacrificed at 2, 8 and 12 weeks postsurgery and bone regeneration was evaluated both histologically and immunohistochemically. RESULTS: Statistically significant differences were observed in bone osteoblastic activity in calvarial defects among the groups (p < 0.05). PRP and MSC used in combination with BCP as a defect filling resulted in greater osteoblastic bone formation activity when compared to the use of BCP alone. CONCLUSIONS: The combination of mesenchymal stem cells, platelet rich plasma and synthetic bone substitute was found to be more effective in inducing new bone formation (osteogenesis) than the use of platelet rich plasma combined with synthetic bone substitute and the use of synthetic bone substitute alone.

Changes in biomechanical strain and morphology of rat calvarial sutures and bone after Tgf-ß3 inhibition of posterior interfrontal suture fusion.

Craniofacial sutures are bone growth fronts that respond and adapt to biomechanical environments. Little is known of the role sutures play in regulating the skull biomechanical environment during patency and fusion conditions, especially how delayed or premature suture fusion will impact skull biomechanics. Tgf-ß3 has been shown to prevent or delay suture fusion over the short term in rat skulls, yet the long-term patency or its consequences in treated sutures is not known. It was therefore hypothesized that Tgf-ß3 had a long-term impact to prevent suture fusion and thus alter the skull biomechanics. In this study, collagen gels containing 3 ng Tgf-ß3 were surgically placed superficial to the posterior interfrontal suture (IFS) and deep to the periosteum in postnatal day 9 (P9) rats. At P9, P24, and P70, biting forces and strains over left parietal bone, posterior IFS, and sagittal suture were measured with masticatory muscles bilaterally stimulated, after which the rats were sacrificed and suture patency analyzed histologically. Results demonstrated that Tgf-ß3 treated sutures showed less fusion over time than control groups, and strain patterns in the skulls of the Tgf-ß3-treated group were different from that of the control group. Although bite force increased with age, no alterations in bite force were attributable to Tgf-ß3 treatment. These findings suggest that the continued presence of patent sutures can affect strain patterns, perhaps when higher bite forces are present as in adult animals.

Mixture of hyaluronic acid, chondroitin 6 sulphate and dermatan sulphate used to completely regenerate bone in rat critical size defect model.

Skeletal bone losses are mainly filled with autologous graft or artificial materials. Osteoblasts are essential to maintain bone homeostasis and bone repair through a matrix synthesis. We have previously demonstrated that adherence and regenerative matrix composition are fundamental to bone healing, even in critical situations. In this work the critical size defect technique was used to evaluate the systemic activity on bone regeneration of a novel mixture of extracellular polysaccharides. A 5mm diameter hole was made in each parietal bone of male Wistar rats. The right parietal bone hole was filled with a mixture of hyaluronic acid, chondroitin 6 sulphate, and dermatan sulphate mixed with 2.5% NaCl solution, while the left hole was left free of material and untreated and considered as control. Twenty-one days after surgery, the holes and surrounding tissues were examined visually, using X-rays, and by histological staining. Using the matrix substitute, bone healing was almost complete after 21 days in the treated hole and always complete in the control side due to some systemic effect. Neovascularization was also observed along with organized trabecular bone on both sides. No abnormal bone growth or connective tissue abnormalities were noted. At the end of the experiment, 95.1% (± 3.2) bone healing (n=20) was observed on the treated side; conversely, healing bone and histological structure were better on the control side.

Effects of zoledronic acid on sutural bone formation: a computed tomography study.

The aim of this study was to investigate the effects of systemically applied zoledronic acid (ZA) on osteoblastic bone formation and relapse in the rat sagittal suture after expansion. Eighteen 12-week-old male Wistar rats were divided into three groups. In groups 1 and 2, a saline solution was given subcutaneously after expansion and the retention period lasted for 14 and 7 days, respectively. In group 3, 0.1 mg of ZA was diluted with saline and given subcutaneously after expansion: the retention period lasted for 7 days. Computed tomography (CT) measurements were obtained at the start of the study (T1), after expansion (T2), after the retention period (T3), and after the follow-up period (T4). The amount of expansion and relapse and the density of the newly formed bone in the expansion area were measured. The mean bone density values in hounsfield unit (HU) of the newly formed bone were recorded using MX View Workstation. Data were analysed using the Kruskal-Wallis, Friedman, Wilcoxon, and Mann-Whitney U-tests. The results showed that there were significant differences between the groups in the density of newly formed bone after the retention period (P < 0.05). Statistically significant differences were observed when the relapse percentages were compared between the groups (P < 0.05). ZA stimulated bone formation and decreased the relapse ratio after expansion in the rat sagittal suture.