Early Phase Of Bone Healing Research Articles

Immunomodulation Using BMP-7 and IL-10 to Enhance the Mineralization Capacity of Bone Progenitor Cells in a Fracture Hematoma-Like Environment.

Following biomaterial implantation, a failure to resolve inflammation during the formation of a fracture hematoma can significantly limit the biomaterial's ability to facilitate bone regeneration. This study aims to combine the immunomodulatory and osteogenic effects of BMP-7 and IL-10 with the regenerative capacity of collagen-hydroxyapatite (CHA) scaffolds to enhance in vitro mineralization in a hematoma-like environment. Incubation of CHA scaffolds with human whole blood leads to rapid adsorption of fibrinogen, significant stiffening of the scaffold, and the formation of a hematoma-like environment characterized by a limited capacity to support the infiltration of human bone progenitor cells, a significant upregulation of inflammatory cytokines and acute phase proteins, and significantly reduced osteoconductivity. CHA scaffolds functionalized with BMP-7 and IL-10 significantly downregulate the production of key inflammatory cytokines, including IL-6, IL-8, and leptin, creating a more permissive environment for mineralization, ultimately enhancing the biomaterial's osteoconductivity. In conclusion, targeting the onset of inflammation in the early phase of bone healing using BMP-7 and IL-10 functionalized CHA scaffolds is a promising approach to effectively downregulate inflammatory processes, while fostering a more permissive environment for bone regeneration.

Bone healing, tissue effects and biomechanical fixation of ‘smooth’ ceramic-coated zirconia-based dental implants: An in vivo study in sheep

In this study, the effect of coating a zirconia-based ceramic oral implant with a material of the same composition to build a relatively smooth surface with three different porosity features was evaluated in vivo, at 4 and 8 weeks after implantation in sheep femoral condyles. The results showed that at 4 weeks, the three coated zirconia-based implants with smoother surface topographies behaved similarly and promoted faster bone healing compared to the results obtained in the same zirconia- or titanium-based implants, but with rougher sandblasted and acid-etched surfaces. In addition, higher pull-out strengths were estimated in the coated-ceramic sample compared to titanium sandblasted and etched one. The present work showed that zirconia coatings with smoother surfaces than those conventionally used in the market improved the early phase of bone healing, paving the way for shorter treatment times and improved patient outcomes.

Influence of Scaffold Microarchitecture on Angiogenesis and Regulation of Cell Differentiation during the Early Phase of Bone Healing: A Transcriptomics and Histological Analysis.

The early phase of bone healing is a complex and poorly understood process. With additive manufacturing, we can generate a specific and customizable library of bone substitutes to explore this phase. In this study, we produced tricalcium phosphate-based scaffolds with microarchitectures composed of filaments of 0.50 mm in diameter, named Fil050G, and 1.25 mm named Fil125G, respectively. The implants were removed after only 10 days in vivo followed by RNA sequencing (RNAseq) and histological analysis. RNAseq results revealed upregulation of adaptive immune response, regulation of cell adhesion, and cell migration-related genes in both of our two constructs. However, significant overexpression of genes linked to angiogenesis, regulation of cell differentiation, ossification, and bone development was observed solely in Fil050G scaffolds. Moreover, quantitative immunohistochemistry of structures positive for laminin revealed a significantly higher number of blood vessels in Fil050G samples. Furthermore, µCT detected a higher amount of mineralized tissue in Fil050G samples suggesting a superior osteoconductive potential. Hence, different filament diameters and distances in bone substitutes significantly influence angiogenesis and regulation of cell differentiation involved in the early phase of bone regeneration, which precedes osteoconductivity and bony bridging seen in later phases and as consequence, impacts the overall clinical outcome.

Microdialysis Reveals Anti-Inflammatory Effects of Sulfated Glycosaminoglycanes in the Early Phase of Bone Healing.

Although chronic inflammation inhibits bone healing, the healing process is initiated by an inflammatory phase. In a well-tuned sequence of molecular events, pro-inflammatory cytokines are secreted to orchestrate the inflammation response to injury and the recruitment of progenitor cells. These events in turn activate the secretion of anti-inflammatory signaling molecules and attract cells and mediators that antagonize the inflammation and initiate the repair phase. Sulfated glycosaminoglycanes (sGAG) are known to interact with cytokines, chemokines and growth factors and, thus, alter the availability, duration and impact of those mediators on the local molecular level. sGAG-coated polycaprolactone-co-lactide (PCL) scaffolds were inserted into critical-size femur defects in adult male Wistar rats. The femur was stabilized with a plate, and the defect was filled with either sGAG-containing PCL scaffolds or autologous bone (positive control). Wound fluid samples obtained by microdialysis were characterized regarding alterations of cytokine concentrations over the first 24 h after surgery. The analyses revealed the inhibition of the pro-inflammatory cytokines IL-1β and MIP-2 in the sGAG-treated groups compared to the positive control. A simultaneous increase of IL-6 and TNF-α indicated advanced regenerative capacity of sGAG, suggesting their potential to improve bone healing.

Low Young's Modulus TiNbSn Alloy Locking Plates Accelerate Osteosynthesis in Rabbit Tibiae.

A new beta TiNbSn alloy with a low Young's modulus of approximately 40 GPa has been developed to resolve the stress shielding by Young's modulus divergence. In this study, the efficacy of TiNbSn alloy locking plates on bone repair is compared to that of commercially pure titanium (CP-Ti). The TiNbSn alloy and CP-Ti, which have Young's moduli of 49.1 GPa and 107 GPa, respectively, were compared. Male Japanese white rabbits were anesthetized, and osteotomy and osteosynthesis with locking plates were performed on the right tibia. The bone repair was assessed using micro-computed tomography (CT), histomorphometry, immunohistochemistry, and mechanical testing. Micro-CT, histomorphometry, immunohistochemistry, and mechanical testing were performed four weeks after osteotomy. Six weeks after surgery, micro-CT and mechanical testing were performed. Micro-CT analysis at four weeks after surgery showed that the intramedullary fracture callus in the TiNbSn alloy group had more bone volume and numerous bridging structures compared to the CP-Ti group (CP-Ti vs. TiNbSn alloy, 34.3 ± 13.1 mm3 vs. 61.3 ± 19.6 mm3, p = 0.02; mean ± standard deviation). At four weeks post-osteotomy, the healed tibia showed significantly higher strength in the TiNbSn alloy group compared with CP-Ti (CP-Ti vs. TiNbSn alloy, 81.3 ± 31.2 N vs. 133.7 ± 46.6 N, p = 0.04). TiNbSn alloy locking plates had a more positive impact on bone formation and bone strength restoration than the CP-Ti locking plates during the early phase of bone healing.

Influence of a Calcium Phosphate Coating (BONIT®) on the Proliferation and Differentiation Potential of Human Mesenchymal Stroma Cells in the Early Phase of Bone Healing.

When implanting osteosynthetic materials or orthopedic implants, the surface condition plays a decisive role for mid- to long-term osseointegration. BONIT®, an electrochemically produced calcium phosphate (CaP) coating, has been used in the surface refinement of implants since 1995. More than 3.5 million coated implants have been successfully placed so far. BONIT® has thus been able to demonstrate clinical success. However, due to its surface properties and solubility, and the resulting difficulty in culturing cells, there are no in vitro studies investigating its influence at the molecular level, particularly on bone metabolism. In a first step, the cells from a total of ten donors were seeded separately on four different surfaces: 1. a pure corundum-blasted titanium surface (CELLTex®, CT), 2. CT with additional BONIT® coating (CT + B), 3. a hydroxyapatite-blasted titanium surface (DUOTex®, DT), 4. DT with additional BONIT® coating (DT + B). In a second step, the cells were grown for 48 h. The proliferation behavior and differentiation potential of hMSCs were investigated at three consecutive time points (12 h, 24 h and 48 h) by quantifying the mRNA expression of ten important differentiation markers using quantitative real-time polymerase chain reaction (qRT-PCR). We were able to show that BONIT® has an influence on the early proliferation and differentiation behavior of hMSCs in patients of all age groups. The additional BONIT® coating on CELLTex® or DUOTex® led to a defined mRNA expression pattern for the investigated factors: a tendency towards a higher expression rate with coating present could be found for bone morphogenetic protein 2 (BMP2), osteopontin (OPN), osteocalcin (OC), receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG). A similar or lower expression rate was detected for runt-related transcription factor 2 (RUNX2), alpha-1 type I collagen (COL1A1), alkaline phosphatase (AP), osteonectin (ON) and insulin-like growth factor I (IGF1). We have developed a new method that allows the cultivation of human mesenchymal stromal cells (hMSCs) on the soluble coating BONIT® for gene expression analysis. BONIT® has a significant influence on the proliferation and differentiation behavior of human mesenchymal stroma cells. This study describes a defined gene expression pattern of bone metabolism that may help to understand the influence of this CaP coating on the early phase of implant osseointegration.

Notch signaling enhances bone regeneration in the zebrafish mandible.

Loss or damage to the mandible caused by trauma, treatment of oral malignancies, and other diseases is treated using bone-grafting techniques that suffer from numerous shortcomings and contraindications. Zebrafish naturally heal large injuries to mandibular bone, offering an opportunity to understand how to boost intrinsic healing potential. Using a novel her6:mCherry Notch reporter, we show that canonical Notch signaling is induced during the initial stages of cartilage callus formation in both mesenchymal cells and chondrocytes following surgical mandibulectomy. We also show that modulation of Notch signaling during the initial post-operative period results in lasting changes to regenerate bone quantity one month later. Pharmacological inhibition of Notch signaling reduces the size of the cartilage callus and delays its conversion into bone, resulting in non-union. Conversely, conditional transgenic activation of Notch signaling accelerates conversion of the cartilage callus into bone, improving bone healing. Given the conserved functions of this pathway in bone repair across vertebrates, we propose that targeted activation of Notch signaling during the early phases of bone healing in mammals may both augment the size of the initial callus and boost its ossification into reparative bone.

Wealth index is significantly associated with the early phase of fracture healing among fractured patients at the University of Gondar Specialized Hospital, Northwest Ethiopia

Bone fracture is a cause of 5 million annual injuries globally. It contributes to profound physical impairment, a reduction in quality of life, long hospitalization time, and reduced institutional care. The socioeconomical impact of bone fracture will be high in the next 50 years in developing countries, including Ethiopia. This study aimed to assess the factors associated with the early phase of fracture healing among fractured adult patients at the University of Gondar Specialized hospital, Northwest Ethiopia. A secondary data analysis was done from the previous institution-based prospective follow-up study from March to June 2015. An interviewer-administered pretested and structured questionnaire was used to collect the data. Early ossification of fractured bone was defined when the bone was ossified/calcified within 1 month of the fracture using X-ray findings. Data were entered into EpiInfo version 3.5.3 software and exported to SPSS version 20 for Windows for further analysis. Binary logistic regression analysis was employed to find factors associated with early ossification of a fractured bone. In the multivariable model, variables that had a p–value of < 0.05 were considered statistically significant. Also, a 95% CI for odds ratios was calculated to see the degree of association. In total, 118 participants with a bone fracture participated in this study. Of all, 36.4% of them had ossified bone during the early phase of bone healing. Dietary diversity score (DDS) [AOR = 18.6, 95% CI (4.10–84.34)], the type of fractured bone [AOR: = 0.13, 95% CI (0.03–0.50)], and household wealth index [AOR = 8.6, 95% CI (1.51–49.05)] were independently associated with the early phase of fractured bone healing/ossification. Bone ossification during the first month of fracture was low. Dietary diversity score, type of fractured bone, and household wealth index were the factors associated with the early phase of bone ossification. So, improving dietary practice after the incident is essential. Also, health care providers will have to consider the fractured bone type and household assets during the clinical intervention for fractured bone.

Human iPSC-derived iMSCs improve bone regeneration in mini-pigs

Autologous bone marrow concentrate (BMC) and mesenchymal stem cells (MSCs) have beneficial effects on the healing of bone defects. To address the shortcomings associated with the use of primary MSCs, induced pluripotent stem cell (iPSC)-derived MSCs (iMSCs) have been proposed as an alternative. The aim of this study was to investigate the bone regeneration potential of human iMSCs combined with calcium phosphate granules (CPG) in critical-size defects in the proximal tibias of mini-pigs in the early phase of bone healing compared to that of a previously reported autograft treatment and treatment with a composite made of either a combination of autologous BMC and CPG or CPG alone. iMSCs were derived from iPSCs originating from human fetal foreskin fibroblasts (HFFs). They were able to differentiate into osteoblasts in vitro, express a plethora of bone morphogenic proteins (BMPs) and secrete paracrine signaling-associated cytokines such as PDGF-AA and osteopontin. Radiologically and histomorphometrically, HFF-iMSC + CPG transplantation resulted in significantly better osseous consolidation than the transplantation of CPG alone and produced no significantly different outcomes compared to the transplantation of autologous BMC + CPG after 6 weeks. The results of this translational study imply that iMSCs represent a valuable future treatment option for load-bearing bone defects in humans.

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

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

Biological Compatibility Profile on Biomaterials for Bone Regeneration.

Large non-union bone fractures are a significant challenge in orthopedic surgery. Although auto- and allogeneic bone grafts are excellent for healing such lesions, there are potential complications with their use. Thus, material scientists are developing synthetic, biocompatible biomaterials to overcome these problems. In this study, we present a multidisciplinary platform for evaluating biomaterials for bone repair. We combined expertise from bone biology and immunology to develop a platform including in vitro osteoclast (OC) and osteoblast (OB) assays and in vivo mouse models of bone repair, immunogenicity, and allergenicity. We demonstrate how to perform the experiments, summarize the results, and report on biomaterial biocompatibility. In particular, we tested OB viability, differentiation, and mineralization and OC viability and differentiation in the context of β-tricalcium phosphate (β-TCP) disks. We also tested a β-TCP/Collagen (β-TCP/C) foam which is a commercially available material used clinically for bone repair in a critical-sized calvarial bone defect mouse model to determine the effects on the early phase of bone healing. In parallel experiments, we evaluated immune and allergic responses in mice. Our approach generates a biological compatibility profile of a bone biomaterial with a range of parameters necessary for predicting the biocompatibility of biomaterials used for bone healing and repair in patients.

Change in serum level of vitamin D and associated factors at early phase of bone healing among fractured adult patients at University of Gondar teaching hospital, Northwest Ethiopia: a prospective follow up study

IntroductionCurrently, Vitamin D deficiency is a major public health problem and it affects more than one billion people worldwide. Vitamin D is crucial for bone mineralization and ossification. Patients with fractures need Vitamin D for the healing of their fractured bone. The current study was carried out to determine if there is change in the serum level of Vitamin–D associated with factors at early phase of fractured bone healing (ossification) process among adult fractured patients at University of Gondar teaching hospital, Northwest Ethiopia.MethodsThis facility-based prospective follow up study was conducted from March to June 2016. Data was collected by an interviewer, and pretested and structured questionnaires were used. Biological samples were collected to determine the serum level of vitamin–D in all subjects. In addition, X–Ray findings were used to determine the early phase of bone healing process. Data was entered into EPI INFO version 3.5.3 and analyzed using the Statistical Package for Social Sciences (SPSS) version 20. Both bivariate and multivariate logistic regression analysis was done to screen for factors associated with decreased serum levels of Vitamin–D. In the Multivariate regression analysis, those variables which had a P–value of <0.05 were considered as independently associated with change in serum level of Vitamin–D.ResultsA total of 118 adult patients with fractures participated in this study. The prevalence of patients’ with decreased serum levels of vitamin–D at post-test was 63.6% [95% CI; (0.551–0.720)]. Inadequate intake of milk and milk products in the 1st week of fracture [AOR = 95%CI: 0.20 (0.05–0.90)], Poor Dietary Diversity Score [AOR = 95% CI: 29.1 (2.27–371.65)], and ossified bone [AOR =95% CI: 4.10 (1.12–14.95)] showed statistically significant association with decreased serum level of Vitamin–D.Conclusion and recommendationsDecreased serum level of Vitamin–D at early phase of fractured bone healing process was found in the majority of patients (>63%) raising concern for Vitamin D deficiency to be a significant public health problem in the study population. It was statistically associated with: poor dietary diversity score, in adequate intake of milk and milk products in the 1stone week of fracture and ossified (healed) bone. Introducing hospital based Vitamin–D supplementation and integrated with health and nutritional education is a vital intervention needed to improve serum levels of Vitamin–D.

Tibiotalocalcaneal Arthrodesis Utilizing a Titanium Intramedullary Nail with an Internal Pseudoelastic Nitinol Compression Element

Category: Ankle, Ankle Arthritis, Hindfoot, Trauma Introduction/Purpose: Fusion construct stability and compression across arthrodesis sites must be optimized in tibiotalocalcaneal (TTC) arthrodesis using a retrograde locking intramedullary nail. Compression generated with modern TTC nails may dissipate with time, theoretically caused by settling of the arthrodesis surfaces and bone resorption during the early phase of bone healing. One millimeter of bone resorption has been shown to dramatically decrease compressive forces across an arthrodesis site. An arthrodesis nail with an internal pseudoelastic nickel titanium alloy (nitinol) compression element has the potential to create sustained compression across tibiotalar and subtalar arthrodesis surfaces. The purpose of this study is to evaluate the effectiveness of this nail in creating and sustaining compression across the tibiotalar and subtalar joints and to report rates of both union and complications. Methods: In this retrospective case series, we hypothesize that union rates will be higher than those reported in the literature. Secondly, we aim to define a more precise CT-based fusion rate for tibiotalocalcaneal arthrodesis. Finally, we aim to provide in vivo evidence of dynamic compression via the internal pseudoelastic nitinol element. A query of the OrthoCarolina administrative database was performed based on the CPT codes for tibiotalar and subtalar arthrodesis from January 2013 to June 2016. CT scans were reviewed on a cut-by-cut basis using sagittal reformats to calculate a percentage of joint surface bony union; at least 50% joint surface bone bridging was used to define union. Intra-operative and post- operative radiographs were calibrated and reviewed in order to measure subsidence (thus continual compression postoperatively) of the nitinol element relative to the intramedullary nail, using the PA screw as a reference. Results: 20 patients were identified and included in analysis. Three patients were excluded. A median of 93% and 84% of the tibiotalar and subtalar joint surfaces united, respectively. Union rate of arthrodesis surfaces among patients without Charcot was 94%. Three patients had Charcot osteoarthopathy and five had talar avascular necrosis; a history of Charcot was a risk factor for nonunion (p=0.04). 87% of all arthrodesis surfaces united. 79% of patients went on to both tibiotalar and subtalar union. The PA screw was found to travel an average of 3.5 mm from intra-operative to initial 2-3 week post-operative radiographs (p&lt;0.0001), providing additional compression postoperatively. 4 revision surgeries were required at a median 9 months post-operative, 2 for deep infection but 0 for delayed or nonunion. Conclusion: Regarding the primary outcome measure, arthrodesis union based on CT scans using a conservative 50% joint surface bone bridging cut-off to define union, the rate of union was high even in the face of challenging clinical scenarios. The percentage of arthrodesis surfaces that fused was higher than anticipated. Unloading of the pseudoelastic nitinol element occurred over the first 2-3 post-operative weeks and represents in vivo evidence that the dynamic compression generated by this nail works.

Evaluation of light-emitting diode photobiomodulation on bone healing of rat calvarial defects

One of the major problems in modern dentistry is the recovery of bone defects. The aim of this prospective experimental study was to evaluate the effect of light-emitting diode (LED) photobiomodulation therapy on bone healing of rat calvarial defects. Twenty-eight male Sprague Dawley rats were used for the study. Critical size defects with 5 mm diameter were made with a trephine bur used in a low-speed handpiece under continuous sterile saline irrigation on each side of the sagittal suture. All critical size defects on the right side were filled with corticocancellous bone graft material and all the defects on the left side were left empty. The animals were randomly divided into two groups of 14 rats each. Group I received LED therapy and Group II did not receive any therapy. OsseoPulse® LED device (Biolux Research Ltd.) 618 nm wavelength and 20 mW/cm2 output power irradiation was started immediately after the surgery and was applied for 20 minutes at 24-h intervals for 7 and 14 days. In each group, seven rats were sacrificed on the 8th day and the remaining rats were sacrificed on the 15th day. Bone healing of the non-grafted side was statistically significant in Group I on both 8th day and 15th day; on the other hand, in the grafted side, enhanced bone healing was dominantly observed on the 15th day in Group I, compared to Group II, although the difference was not significant. Within the limits of this study, the findings suggested that LED therapy might have a favourable effect in the early phase of bone healing.

Improved bone defect healing by a superagonistic GDF5 variant derived from a patient with multiple synostoses syndrome

Multiple synostoses syndrome 2 (SYNS2) is a rare genetic disease characterized by multiple fusions of the joints of the extremities, like phalangeal joints, carpal and tarsal joints or the knee and elbows. SYNS2 is caused by point mutations in the Growth and Differentiation Factor 5 (GDF5), which plays an essential role during skeletal development and regeneration. We selected one of the SYNS2-causing GDF5 mutations, p.N445T, which is known to destabilize the interaction with the Bone Morphogenetic Protein (BMP) antagonist NOGGIN (NOG), in order to generate the superagonistic GDF5 variant GDF5N445T. In this study, we tested its capacity to support regeneration in a rat critical-sized defect model in vivo. MicroCT and histological analyses indicate that GDF5N445T-treated defects show faster and more efficient healing compared to GDF5 wild type (GDF5wt)-treated defects. Microarray-based gene expression and quantitative PCR analyses from callus tissue point to a specific acceleration of the early phases of bone healing, comprising the inflammation and chondrogenesis phase. These results support the concept that disease-deduced growth factor variants are promising lead structures for novel therapeutics with improved clinical activities.

The Early Phases of Bone Healing Can Be Differentiated in a Rat Osteotomy Model by Focused Transverse-Transmission Ultrasound

Here we describe the use of a 5-MHz focused transmission system to image the bone repair region and to distinguish the early healing phases in a rat osteotomy (OT) model. Twelve-month-old female rats underwent a 2-mm OT. After 6 wk of consolidation, 2-D projection images of time-of-flight, speed of sound, and ultrasound attenuation were measured in vitro. The tissue types in the OT gap region were assessed by site-matched histology sections and micro-computed tomography (μCT). In the cases investigated, OT gap regions containing fibrous tissue (group A) were found to have similar properties compared with adjacent muscle tissue, whereas regions filled with cartilage and mineralized callus tissues (group B) differed significantly. Analysis of variance revealed that the healing group had a stronger effect on acoustic parameters (F < 35) than on μCT-based parameters (F < 22). This pilot study reports the feasibility of transverse transmission quantitative ultrasound in assessment of the onset of cartilage formation during callus formation.

Effect of PDGF-BB, IGF-I Growth Factors and their Combination Carried by Liposomes in Tooth Socket Healing

This work evaluated the bone-forming potential of the platelet-derived growth factor isoform BB (PDGF-BB), insulin-like growth factor I (IGF-I), and mixed PDGF-BB/IGF-I delivered in liposomes compared with phosphate buffered saline (PBS), in the healing process of rat tooth sockets. One hundred and twelve Wistar rats were randomized into 7 groups of 16 animals each and were evaluated at 3, 7, 14 and 21 days after extraction of the maxillary second molars. The left sockets were treated with PBS (P), empty liposome (L), IGF-I in PBS (IP), IGF-I in liposome (IL), PDGF-BB in PBS (PDP), PDGF-BB in liposome (PDL) and both growth factors (GFs) together within liposomes (PDIL). The right sockets were filled with blood clot (BC). Histological and histomorphometric analyses were used to evaluate the formation of new bone and blood vessels. Immunohistochemistry was performed to evaluate the expression of osteocalcin and vascular endothelial growth factor (VEGF) during bone repair. Data were tested statistically using a Tukey's test according to a Dunn's analysis and Mann-Whitney U test followed by Kruskal-Wallis one-way analysis. Results were considered significant when p<0.05. A significantly higher percentage of bone trabeculae and a higher number of blood vessels were observed in the IL, PDL and PDIL groups (p<0.05). However, these GF-liposome groups had statistically similar results. Immunohistochemical assays first detected osteocalcin and VEGF expression at 3 days followed by a peak at 7 days. Lower immunoreactivity levels were observed in the BC, L, P, IP and PDP groups compared with the IL, PDL and PDIL groups (p<0.05). The results suggest that GFs carried by liposomes, either in isolated or mixed forms, enhanced the healing process in rat tooth sockets. The differential expression of the osteogenic markers VEGF and osteocalcin in the early phases of bone healing support these findings.

The early phase influence of bone marrow concentrate on metaphyseal bone healing

Bone marrow concentrate (BMC) contains high densities of progenitor cells. Therefore, in critical size defects BMC may have the potency to support bone healing. The aim of this study was to investigate the effect of BMC in combination with calcium phosphate granules (CPG) on bone defect healing in a metaphyseal long bone defect in mini-pigs. A metaphyseal critical-size bone defect at the proximal tibia of 24 mini-pigs was filled with CPG combined with BMC, CPG solely (control group) or with an autograft. Radiological and histomorphometrical evaluations after 6 weeks (42 days) showed significantly more bone formation in the BMC group in the central area of the defect zone and the cortical defect zone compared to the CPG group. At the same time the resorption rate of CPG increased significantly in the BMC group. Nevertheless, compared to the BMC group the autograft group showed a significantly higher new bone formation radiologically and histomorphometrically. In BMC the count of mononuclear cells was significantly higher compared to the bone marrow aspirate (3.5-fold). The mesenchymal progenitor cell characteristics of the cells in BMC were confirmed by flow cytometry. Cells from BMC created significantly larger colonies of alkaline phosphatase-positive colony forming units (CFU-ALP) (4.4-fold) compared to cells from bone marrow aspirate. Nevertheless, even in the BMC group complete osseous bridging was only detectable in isolated instances of the bone defects. Within the limitations of this study the BMC+CPG composite promotes bone regeneration in the early phase of bone healing significantly better than the isolated application of CPG. However, the addition of BMC does not lead to a solid fusion of the defect in the early phase of bone healing an still does not represent an equal alternative to autologous bone.

Serum levels of fibroblast growth factor 2 in children with orthopedic diseases: Potential role in predicting bone healing

Fibroblast growth factor 2 (FGF-2) plays an important role in the early phases of bone healing. In this study, we measured FGF-2 serum levels in 88 children undergoing surgical treatment for congenital (n = 49) or acquired (n = 39) orthopedic conditions, which were associated (n = 35) or not (n = 53) with bone lesions, to assess whether serum levels of FGF-2 varied according to the underlying disease and may predict clinical outcomes. FGF-2 serum levels were significantly lower in patients who did not heal after surgery (p = 0.008). Diagnostic accuracy was validated statistically, and the ROC curve provided a threshold value useful in discriminating good versus poor outcomes. The relationship between FGF-2 and bone healing was supported by in vitro experiments. A mineralization assay was performed on bone marrow stromal cells from three patients with congenital pseudarthrosis, who had low serum levels of FGF-2 and a poor clinical outcome after surgical treatment. Autologous serum alone was not sufficient to induce in vitro mineralization, but it did occur when cells were cultured with different sources of exogenous growth factors (GFs), including recombinant FGF-2 and homologous serum collected from children with fractures, high FGF-2 levels, and a good clinical outcome. In conclusion, our findings suggest that osteoinductive GFs are essential for bone repair, and that the amount of circulating FGF-2 may predict bone healing.

Synthetic Peptide-conjugated Titanium Alloy for Enhanced Bone Formation In Vivo

There are growing demands for bioactive titanium implants that could shorten the healing period, promote faster rehabilitation, and thereby increase the success rate of treating patients with poor bone quality. A synthetic receptor-binding peptide mimicking bone morphogenetic protein-2 (BMP-2) was covalently linked to a titanium alloy with two types of topography—machined (TiMA) and rough (TiGB)—by using a chemical conjugation process. In vivo osseointegration capacity was evaluated chronologically using histomorphometric analysis at 2, 4, and 8 weeks after implantation in the distal femurs of rabbits. In the histologic examinations, peri-implant bone formation was more active around TiGB than TiMA. Compared to the control groups (nonconjugated TiMA and TiGB) at 2, 4, and 8 weeks, the peptide-conjugated groups (TiMA-P and TiGB-P) had more mature new bone, thicker trabeculae, more rapid bone maturation, and higher affinity index (percentage of new bone contact length) in histomorphometric analysis. Particularly, differences in the affinity index between the peptide-conjugated and nonconjugated groups were more pronounced at the early phase of peri-implant healing (2 and 4 weeks). However, at 8 weeks, enhanced bone formation was less prominent according to peptide conjugation, especially in specimens with a rough surface. The titanium alloys in the rabbit femurs led to a significant increase of bone growth when modified with bioactive peptides, especially during the early phase of bone healing. These results confirm that biochemical modifications of titanium surfaces can enhance the rate of bone healing compared with that of untreated titanium surfaces.