Variability of BMP-2 content in DBM products derived from different long bone.

Demineralized bone matrix (DBM) has been regarded as an ideal bone substitute as a native carrier of bone morphogenetic proteins (BMPs) and other growth factors. However, the osteoinductive properties diverse in different DBM products. We speculate that the harvest origin further contributing to variability of BMPs contents in DBM products besides the process technology. In the study, the cortical bone of femur, tibia, humerus, and ulna from a signal donor were prepared and followed demineralizd into DBM products. Proteins in bone martix were extracted using guanidine-HCl and collagenase, respectively, and BMP-2 content was detected by sandwich enzyme-linked immunosorbent assay (ELISA). Variability of BMP-2 content was found in 4 different DBM products. By guanidine-HCl extraction, the average concentration in DBMs harvested from ulna, humerus, tibia, and femur were 0.613 ± 0.053, 0.848 ± 0.051, 3.293 ± 0.268, and 21.763 ± 0.344, respectively (p < 0.05), while using collagenase, the levels were 0.089 ± 0.004, 0.097 ± 0.004, 0.330 ± 0.012, and 1.562 ± 0.008, respectively (p < 0.05). In general, the content of BMP-2 in long bones of Lower limb was higher than that in long bones of upper limb, and GuHCl had remarkably superior extracted efficiency for BMP-2 compared to collagenase. The results suggest that the origin of cortical bones harvested to fabricate DBM products contribute to the variability of native BMP-2 content, while the protein extracted method only changes the measured values of BMP-2.

Evaluation of BMP-2, VEGF, and Vitamin D Receptor Levels in the Ligamentum Flavum of Patients with Lumbar Spinal Stenosis and Disc Herniation.

AIM: To histopathologically evaluate and compare bone morphogenetic protein (BMP)-2, vascular endothelial growth factor (VEGF), and vitamin D receptor (VDR) levels in the ligamentum flavum (LF) of patients with lumbar spinal stenosis (LSS) and lumbar disc herniation (LDH). MATERIAL AND METHODS: Surgical specimens of the LF in 25 patients who underwent surgery for LDH and 25 patients who underwent surgery for LSS were examined histopathologically. The prevalence and severity of BMP-2, VEGF, and VDR immunoreactivity were evaluated to create histoscores (prevalence × severity), which were compared between groups. RESULTS: The mean BMP-2 histoscore was similar in both groups. In the LSS group, the mean VEGF histoscore was significantly higher and the mean VDR histoscore was significantly lower. CONCLUSION: Elevated VEGF and decreased VDR levels in the LF in LSS are associated with more intense inflammation and chronic process of the disease. The prominent expression of BMP-2 in the LF in both diseases suggests that BMP-2 might be affected by inflammation regardless of chronic pressure and degeneration.

Examination of the Role of Cells in Commercially Available Cellular Allografts in Spine Fusion: An in Vivo Animal Study.

BACKGROUND: Despite the extensive use of cellular bone matrices (CBMs) in spine surgery, there is little evidence to support the contribution of cells within CBMs to bone formation. The objective of this study was to determine the contribution of cells to spinal fusion by direct comparisons among viable CBMs, devitalized CBMs, and cell-free demineralized bone matrix (DBM). METHODS: Three commercially available grafts were tested: a CBM containing particulate DBM (CBM-particulate), a CBM containing DBM fibers (CBM-fiber), and a cell-free product with DBM fibers only (DBM-fiber). CBMs were used in viable states (CBM-particulatev and CBM-fiberv) and devitalized (lyophilized) states (CBM-particulated and CBM-fiberd), resulting in 5 groups. Viable cell counts and bone morphogenetic protein-2 (BMP-2) content on enzyme-linked immunosorbent assay (ELISA) within each graft material were measured. A single-level posterolateral lumbar fusion was performed on 45 athymic rats with 3 lots of each product implanted into 9 animals per group. After 6 weeks, fusion was assessed using manual palpation, micro-computed tomography (µ-CT), and histological analysis. RESULTS: The 2 groups with viable cells were comparable with respect to cell counts, and pairwise comparisons showed no significant differences in BMP-2 content across the 5 groups. Manual palpation demonstrated fusion rates of 9 of 9 in the DBM-fiber specimens, 9 of 9 in the CBM-fiberd specimens, 8 of 9 in the CBM-fiberv specimens, and 0 of 9 in both CBM-particulate groups. The µ-CT maturity grade was significantly higher in the DBM-fiber group (2.78 ± 0.55) compared with the other groups (p < 0.0001), while none of the CBM-particulate samples demonstrated intertransverse fusion in qualitative assessments. The viable and devitalized samples in each CBM group were comparable with regard to fusion rates, bone volume fraction, µ-CT maturity grade, and histological features. CONCLUSIONS: The cellular component of 2 commercially available CBMs yielded no additional benefits in terms of spinal fusion. Meanwhile, the groups with a fiber-based DBM demonstrated significantly higher fusion outcomes compared with the CBM groups with particulate DBM, indicating that the DBM component is probably the key determinant of fusion. CLINICAL RELEVANCE: Data from the current study demonstrate that cells yielded no additional benefit in spinal fusion and emphasize the need for well-designed clinical studies on cellular graft materials.

The role of TRPM7 in vascular calcification: Comparison between phosphate and uremic toxin.

AIMS: Vascular calcification is a common complication in patients with chronic kidney disease and associated with increased morbidity and mortality. The role of TRPM7 in vascular smooth muscle cell (VSMC) transformation during vascular calcification is not clear. We aim to investigate the effects of phosphate and indoxyl sulphate on the expression of TRPM7 and calcification-related molecules in VSMC. MAIN METHODS: Human aortic smooth muscle cells (HASMC) were treated with phosphate (3.3 mM) or indoxyl sulphate (500 µM and 1000 µM). 2-APB, a channel blocker of TRPM7 was added simultaneously in blocking experiment. Cells were then examined grossly and alizarin red solution was employed for calcification assessment. Lastly, cells were harvested for gene expression and protein abundance analysis. KEY FINDINGS: Phosphate treatment induced significant increase in BMP2, RUNX2, BMP7, vitamin D receptor (VDR), calcium sensing receptor (CaSR) and TRPM7, but 1-alpha hydroxylase, klotho, DKK1 and sclerostin were not changed. The addition of 2-APB prevented increase of BMP2, RUNX2, BMP7, VDR, CaSR and TRPM7. Indoxyl sulphate treatment was associated with decrease in TRPM7 and DKK1, but increase in RUNX2, BMP2 and VDR were noted. There were no significant alterations in BMP7, CaSR, klotho,1-alpha hydroxylase and sclerostin. Co-treatment with 2-APB reversed the increase in VDR. SIGNIFICANCE: Both phosphate and indoxyl sulphate induced calcification in VSMC but it was more prominent in phosphate. TRPM7 was upregulated by phosphate but downregulated in indoxyl sulphate treatment. Vascular calcification was reduced by blocking TRPM7 with 2-APB and there was partial anti-calcification effect in indoxyl sulphate.

Cyclosporine A impairs bone repair in critical defects filled with different osteoconductive bone substitutes.

The aim of this study was to assess the influence of cyclosporine administration on the repair of critical-sized calvaria defects (CSDs) in rat calvaria filled with diverse biomaterials. Sixty animals were divided into two groups: the control (CTR) group (saline solution) and the cyclosporine (CCP) group (cyclosporine, 10 mg/kg/day). These medications were administered daily by gavage, beginning 15 days before the surgical procedure and lasting until the day the animals were euthanized. A CSD (5 mm Ø) was made in the calvaria of each animal, which was allocated to one of 3 subgroups, according to the biomaterial used to fill the defect: coagulum (COA), deproteinized bovine bone (DBB), or biphasic calcium phosphate ceramics of hydroxyapatite and ß-phosphate tricalcium (HA/TCP). Euthanasia of the animals was performed 15 and 60 days after the surgical procedure (n = 5 animals/period/subgroup). Bone repair (formation) assessment was performed through microtomography and histometry, while the analyses of the expression of the BMP2, Osteocalcin, and TGFß1 proteins were performed using immunohistochemistry. The CSDs not filled with biomaterials demonstrated lower bone formation in the CCP group. At 15 days, less bone formation was observed in the CSDs filled with DBB, a smaller volume of mineralized tissue was observed in the CSDs filled with HA/TCP, and the expression levels of BMP2 and osteocalcin were lower in the CCP group compared to the CTR group. The use of cyclosporine impaired bone repair in CSD, and this effect can be partially explained by the suppression of BMP2 and osteocalcin expression.

Cyclosporine A impairs bone repair in critical defects filled with different osteoconductive bone substitutes

Abstract The aim of this study was to assess the influence of cyclosporine administration on the repair of critical-sized calvaria defects (CSDs) in rat calvaria filled with diverse biomaterials. Sixty animals were divided into two groups: the control (CTR) group (saline solution) and the cyclosporine (CCP) group (cyclosporine, 10 mg/kg/day). These medications were administered daily by gavage, beginning 15 days before the surgical procedure and lasting until the day the animals were euthanized. A CSD (5 mm Ø) was made in the calvaria of each animal, which was allocated to one of 3 subgroups, according to the biomaterial used to fill the defect: coagulum (COA), deproteinized bovine bone (DBB), or biphasic calcium phosphate ceramics of hydroxyapatite and β-phosphate tricalcium (HA/TCP). Euthanasia of the animals was performed 15 and 60 days after the surgical procedure (n = 5 animals/period/subgroup). Bone repair (formation) assessment was performed through microtomography and histometry, while the analyses of the expression of the BMP2, Osteocalcin, and TGFβ1 proteins were performed using immunohistochemistry. The CSDs not filled with biomaterials demonstrated lower bone formation in the CCP group. At 15 days, less bone formation was observed in the CSDs filled with DBB, a smaller volume of mineralized tissue was observed in the CSDs filled with HA/TCP, and the expression levels of BMP2 and osteocalcin were lower in the CCP group compared to the CTR group. The use of cyclosporine impaired bone repair in CSD, and this effect can be partially explained by the suppression of BMP2 and osteocalcin expression.

Cyclosporine A impairs bone repair in critical defects filled with different osteoconductive bone substitutes

Abstract The aim of this study was to assess the influence of cyclosporine administration on the repair of critical-sized calvaria defects (CSDs) in rat calvaria filled with diverse biomaterials. Sixty animals were divided into two groups: the control (CTR) group (saline solution) and the cyclosporine (CCP) group (cyclosporine, 10 mg/kg/day). These medications were administered daily by gavage, beginning 15 days before the surgical procedure and lasting until the day the animals were euthanized. A CSD (5 mm Ø) was made in the calvaria of each animal, which was allocated to one of 3 subgroups, according to the biomaterial used to fill the defect: coagulum (COA), deproteinized bovine bone (DBB), or biphasic calcium phosphate ceramics of hydroxyapatite and β-phosphate tricalcium (HA/TCP). Euthanasia of the animals was performed 15 and 60 days after the surgical procedure (n = 5 animals/period/subgroup). Bone repair (formation) assessment was performed through microtomography and histometry, while the analyses of the expression of the BMP2, Osteocalcin, and TGFβ1 proteins were performed using immunohistochemistry. The CSDs not filled with biomaterials demonstrated lower bone formation in the CCP group. At 15 days, less bone formation was observed in the CSDs filled with DBB, a smaller volume of mineralized tissue was observed in the CSDs filled with HA/TCP, and the expression levels of BMP2 and osteocalcin were lower in the CCP group compared to the CTR group. The use of cyclosporine impaired bone repair in CSD, and this effect can be partially explained by the suppression of BMP2 and osteocalcin expression.

Incremental effects of diabetes mellitus and chronic kidney disease in medial arterial calcification: Synergistic pathways for peripheral artery disease progression.

Diabetes mellitus (DM) and chronic kidney disease (CKD) separately are known to facilitate the progression of medial arterial calcification (MAC) in patients with symptomatic peripheral artery disease (PAD), but their combined effect on MAC and associated mediators of calcification is not well studied. The association of MAC and calcification inducer bone morphogenetic protein (BMP-2) and inhibitor fetuin-A, with PAD, is well known. Our aim was to investigate the association of MAC with alterations in BMP-2 and fetuin-A protein expression in patients with PAD with DM and/or CKD. Peripheral artery plaques (50) collected during directional atherectomy from symptomatic patients with PAD were evaluated, grouped into no-DM/no-CKD (n = 14), DM alone (n = 10), CKD alone (n = 12), and DM+CKD (n = 14). MAC density was evaluated using hematoxylin and eosin, and alizarin red stain. Analysis of inflammation, neovascularization, BMP-2 and fetuin-A protein density was performed by immunohistochemistry. MAC density, inflammation grade and neovessel content were significantly higher in DM+CKD versus no-DM/no-CKD and CKD (p < 0.01). BMP-2 protein density was significantly higher in DM+CKD versus all other groups (p < 0.01), whereas fetuin-A protein density was significantly lower in DM+CKD versus all other groups (p < 0.001). The combined presence of DM+CKD may be associated with MAC severity in PAD plaques more so than DM or CKD alone, as illustrated in this study, where levels of calcification mediators BMP-2 and fetuin-A protein were related most robustly to DM+CKD. Further understanding of mechanisms involved in mediating calcification and their association with DM and CKD may be useful in improving management and developing therapeutic interventions.

BMP-2 and type I collagen preservation in human deciduous teeth after demineralization.

BACKGROUND: Great interest has recently been focused on tooth and tooth derivatives as suitable substrates for the treatment of alveolar bone defects. Here, we propose the use of demineralized baby teeth (BT) as potential grafting materials for bone augmentation procedures. METHODS: Particles of human BT (Ø < 1 mm) were demineralized by means of a chemical/thermal treatment. Demineralized BT particles were thoroughly characterized by scanning electron microscopy/energy dispersive X-ray analyses to evaluate the effects of the demineralization on BT topography and mineral phase composition, and by enzyme-linked immunosorbent assays (ELISA) to quantify collagen and bone morphogenetic protein-2 (BMP-2) protein contents. The response of SAOS-2 cells to exogenous BMP-2 stimulation was evaluated to identify the minimum BMP-2 concentration able to induce osteodifferentiation in vitro (alkaline phosphatase (ALP) activity). RESULTS: The demineralization treatment led to a dramatic decrease in relative Ca and P content (%) of ≈75% with respect to the native BT particles, while preserving native protein conformation and activity. Interestingly, the demineralization process led to a rise in the bioavailability of BMP-2 in BT particles, as compared to the untreated counterparts. The BMP-2 content found in demineralized BT was also proved to be very effective in enhancing ALP activity, thus in the osteodifferentiation of SAOS-2 cells in vitro, as confirmed by cell experiments performed upon exogenously added BMP-2. CONCLUSIONS: In this study we demonstrate that the BMP-2 content found in demineralized BT is very effective in inducing cell osteodifferentiation, and strengthens the idea that BTs are very attractive bioactive materials for bone-grafting procedures.

The topography and proliferative activity of cells immunoreactive to various growth factors in rat femoral bone tissues after experimental fracture and implantation of titanium implants with bioactive biodegradable coatings.

BACKGROUND: Biodegradable implant coatings promote proliferation and expression of BMP-2, VEGF, and TGF-ß2 genes and enhance BMP-2, VEGF, and TGF-ß2 regulatory effects at different stages of reparative osteogenesis. OBJECTIVE: To study the topography and ratio of PCNA-, VEGF-, BMP-2-, and TGF-ß2-immunoreactive cells in rat femoral bone after closed fracture and implantation of titanium implants with biodegradable calcium phosphate and hydroxyapatite coatings. METHODS: Standard titanium implant screws and similar implants with bioactive coatings were used. A total of 18 rats were randomly divided into three groups, two experimental and a control one. The rats in the first experimental group were implanted with implants without specific coating, while those in the second group, with implants with specific coatings. The control rats were subjected to the same fracture as the experimental ones without subsequent implantation. On days 7, 14, and 30 of experiment, the rats were sampled for histological examination. Histological sections were prepared and processed for PCNA, BMP-2, VEGF, and TGF-ß2 immunoreactivity. RESULTS: In the regeneration zone, PCNA-immunoreactive cells substantially outnumbered other immunoreactive cell types. During the first two weeks after fracture, in the immediate vicinity of implant surface, the rate of VEGF production increased in osteoblast subpopulations and level of TGF-32 immunoreactivity decreased in chondroblasts. The level of TGF-32 was maximum on day 30 of experiment. BMP-2-immunoreactive osteocytes were found in the zone of external general plates. They accumulated at implants with calcium phosphate coating. Their number gradually increased by day 30 of experiment. CONCLUSIONS: The present data suggest that biodegradable implant coatings promote proliferation and expression of BMP-2, VEGF, and TGF-ß2 genes and enhance BMP-2, VEGF, and TGF-ß2 regulatory effects at different stages of reparative osteogenesis.

Protective Mechanism of Adipose-Derived Stem Cells in Remodelling of the Skin Stem Cell Niche During Photoaging.

BACKGROUND/AIMS: Skin photoaging is primarily caused by the functional attrition of skin stem cells. The skin stem cell niche plays an important role in maintaining stem cell survival and behaviour. In our study, we hypothesized that UVB irradiation induces skin photoaging by changing skin stem cell niches and that transferred adipose-derived stem cells (ADSCs) can remodel the niches by affecting the BMP signalling pathway and transdifferentiating into skin stem cells. METHODS: Sixty-four C57BL/6J mice were divided into the following groups: a control group, the UVB group and the UVB+ADSCs group. Western blot assays, immunofluorescence analysis and real-time PCR were used to measure differences in the expression of niche components among the three groups. Furthermore, we tested whether transplanted ADSCs express skin stem cell markers, such as p63, α6-integrin and CD34. RESULTS: The expression levels of Bmp4, its downstream factors Smad1 and MAPK1 and a regulatory factor of the niche, i.e., NFATc1, were lower in the UVB group than were those in the control group (P< 0.05) but higher in the UVB+ADSCs group than were those in the UVB group (P< 0.05). Compared with Bmp4, Nanog (a downstream factor of Bmp4), and MMP13 (a regulatory factor of the niche), ICAM-1 (a proinflammatory gene), p63 (a basal transcription factor), ß1-integrin, Mtnr1a and Tyr (melanogenesis-related factors) showed the opposite expression trends (P< 0.05). Bmp2 and Collagen IV levels did not significantly change among the three groups (P> 0.05). Skin stem cell markers, such as p63, α6-integrin and CD34, were coexpressed in the ADSCs, which suggested the ADSCs may transdifferentiate into skin stem cells. CONCLUSION: We found that UVB irradiation results in typical photoaging signs by altering skin stem cell niches and that Bmp4 was a key factor in BMP signalling in hair follicles. ADSCs reversed these typical photoaging signs by remodelling skin stem cell niches through BMP4 pathway modulation and transdifferentiation into skin stem cells.

Imaging of growth factors on a human tooth root canal by surface-enhanced Raman spectroscopy.

Endodontic treatment of immature permanent teeth with necrotic pulp poses several clinical challenges and is one of the most demanding interventions in endodontics. Recently, with new discoveries in the field of tissue engineering, novel treatment protocols have been established. The most promising treatment modality is revascularization, whose integral part is the exposure of collagen matrix and embedded growth factors. However, optimization of the treatment protocol requires a development of analytical procedures able to analyze growth factors directly on the sample surface. In this work, method based on surface-enhanced Raman spectroscopy (SERS) was developed to investigate the influence of the time of the medical treatment using EDTA on exposure and accessibility of the growth factors, namely TGF-ß1, BMP-2, and bFGF on the dentine surface. The nanotags, which consist of magnetic Fe3O4@Ag nanocomposite covalently functionalized by tagged antibodies (anti-TGF-ß1-Cy3, anti-BMP-2-Cy5, and anti-bFGF-Cy7), were employed as a SERS substrate. Each antibody was coupled with a unique label allowing us to perform a parallel analysis of all three growth factors within one analytical run. Developed methodology presents an interesting alternative to a fluorescence microscopy and in contrary allows evaluating a chemical composition and thus minimizing possible false-positive results. Graphical abstract.

Non-invasive tri-modal visualisation via PET/SPECT/µCT of recombinant human bone morphogenetic protein-2 retention and associated bone regeneration: A proof of concept.

Bone morphogenetic proteins (BMP's) are vital for bone and cartilage formation, where bone morphogenetic protein-2 (BMP-2) is acknowledged as a growth factor in osteoblast differentiation. However, uncontrolled delivery may result in adverse clinical effects. In this study we investigated the possibility for longitudinal and non-invasive monitoring of implanted [125I]BMP-2 retention and its relation to ossification at the site of implantation. A unilateral critically sized femoral defect was produced in the left limb of rats while the right femur was retained intact as a paired reference control. The defect was filled with a hyaluronan hydrogel with 25% hydroxyapatite alone (carrier control; n = 2) or combined with a mixture of [125I]BMP-2 (150 µg/ml; n = 4). Bone formation was monitored using micro computed tomography (µCT) scans at 1, 3, 5, 7, 9 and 12 weeks. The retention of [125I]BMP-2 was assessed with single photon emission computed tomography (SPECT), and the bone healing process was followed with sodium fluoride (Na18F) using positron emission tomography (PET) at day 3 and at week 2, 4, and 6. A rapid burst release of [125I]BMP-2 was detected via SPECT. This was followed by a progressive increase in uptake levels of [18F]fluoride depicted by PET imaging that was confirmed as bone formation via µCT. We propose that this functional, non-invasive imaging method allows tri-modal visualisation of the release of BMP-2 and the following in vivo response. We suggest that the potential of this novel technique could be considered for preclinical evaluation of novel smart materials on bone regeneration.

Mg-based bone implants show promising osteoinductivity and controllable degradation: A long-term study in a goat femoral condyle fracture model.

In this work, the in vivo biocompatibility and biodegradation behavior of Mg-Nd-Zn-Zr alloy (denoted as JDBM) screws were studied using a goat femoral condyle fracture model. Blood analysis indicates that the liver and kidney functions of goats were not affected by JDBM, JDBM coated with brushite (denoted as JDBM-DCPD) and PLA implants. Radiographic analysis shows that JDBM-DCPD screw has lower degradation rate than JDBM. Histological images show that compared with PLA, JDBM and JDBM-DCPD show superior effect to promote more new bone formation. JDBM-DCPD group has more new bone formation than JDBM group, indicating good osteoinductivity of DCPD coating. JDBM group show higher osteogenic factors level (BMP2, ALP and OC) in peri-implant callus tissue than PLA group. Long-term (18months) in vivo implants Micro-CT result shows that the degradation of JDBM-DCPD screw may be slower than desirable, and the thickness of DCPD coating could be further adjusted to match the degradation to the bone recovery.

Collagen I derived recombinant protein microspheres as novel delivery vehicles for bone morphogenetic protein-2.

Bone morphogenetic protein-2 (BMP-2) is a powerful osteoinductive protein; however, there is a need for the development of a safe and efficient BMP-2 release system for bone regeneration therapies. Recombinant extracellular matrix proteins are promising next generation biomaterials since the proteins are well-defined, reproducible and can be tailored for specific applications. In this study, we have developed a novel and versatile BMP-2 delivery system using microspheres from a recombinant protein based on human collagen I (RCP). In general, a two-phase release pattern was observed while the majority of BMP-2 was retained in the microspheres for at least two weeks. Among different parameters studied, the crosslinking and the size of the RCP microspheres changed the in vitro BMP-2 release kinetics significantly. Increasing the chemical crosslinking (hexamethylene diisocyanide) degree decreased the amount of initial burst release (24h) from 23% to 17%. Crosslinking by dehydrothermal treatment further decreased the burst release to 11%. Interestingly, the 50 and 72µm-sized spheres showed a significant decrease in the burst release compared to 207-µm sized spheres. Very importantly, using a reporter cell line, the released BMP-2 was shown to be bioactive. SPR data showed that N-terminal sequence of BMP-2 was important for the binding and retention of BMP-2 and suggested the presence of a specific binding epitope on RCP (KD: 1.2nM). This study demonstrated that the presented RCP microspheres are promising versatile BMP-2 delivery vehicles.

Use of a fluorescent probe to monitor the enhanced affinity of rh-BMP-2 to silicated-calcium phosphate synthetic bone graft substitutes under competitive conditions.

A comparative investigation was undertaken on 1-2mm sized granules of two forms of synthetic bone graft substitute (SBG) with identical pore structure but varied bulk chemistry, stoichiometric hydroxyapatite (HA) and silicate substituted (0.8wt% Si) hydroxyapatite (SA), to assess the influence of SBG chemistry on the relative affinity of an osteogenic growth factor (GF), recombinant human bone morphogenetic protein-2 (rhBMP-2). A previously described novel fluorescent probe, fluoresceinthioureidoaminocaproic acid (FTCA), was covalently attached to rhBMP-2 to give FTCA-rhBMP-2 and facilitate the quantitative monitoring of GF uptake and release from the two chemistries of SBG. The relative affinity of rhBMP-2 for the HA and SA granules was assessed at a physiologically relevant concentration of 300ngmL-1 from three (increasingly complex) environments; phosphate buffered saline (PBS), minimum Eagles' medium (MEM) and serum supplemented MEM (SCEM) in order to closely mimic clinical bone repair procedures. The results demonstrated that rhBMP-2 affinity to SBGs was highly sensitive to both SBG chemistry and the composition of the local environment. Under the most physiologically relevant competitive conditions of SCEM, rhBMP-2 showed greater affinity to SA (P<0.05) such that 50% of the rhBMP-2 in solution was adsorbed to the SA granules after only 15min, as compared to 30% adsorbed to the HA granules. Subsequent investigation of the desorption of adsorbed GF from the SBGs demonstrated that a significantly higher percentage of the adsorbed rhBMP-2 was desorbed from HA as compared to SA granules. Together, these observations suggested that at physiologically relevant concentrations and conditions, rhBMP-2 has a greater affinity to silicate-substituted hydroxyapatite as compared to stoichiometric hydroxyapatite, which may in part explain the enhanced osteoconductivity and reported osteoinductivity for silicate-substituted hydroxyapatite based SBGs.

Peripheral denervation participates in heterotopic ossification in a spinal cord injury model.

We previously reported the development of a new acquired neurogenic HO (NHO) mouse model, combining spinal cord transection (SCI) and chemical muscle injury. Pathological mechanisms responsible for ectopic osteogenesis after central neurological damage are still to be elucidated. In this study, we first hypothesized that peripheral nervous system (PNS) might convey pathological signals from injured spinal cord to muscles in NHO mouse model. Secondly, we sought to determine whether SCI could lead to intramuscular modifications of BMP2 signaling pathways. Twenty one C57Bl6 mice were included in this protocol. Bilateral cardiotoxin (CTX) injection in hamstring muscles was associated with a two-stage surgical procedure, combining thoracic SCI with unilateral peripheral denervation. Volumes of HO (Bone Volume, BV) were measured 28 days after surgery using micro-computed tomography imaging techniques and histological analyses were made to confirm intramuscular osteogenesis. Volume comparisons were conducted between right and left hind limb of each animal, using a Wilcoxon signed rank test. Quantitative polymerase chain reaction (qPCR) was performed to explore intra muscular expression of BMP2, Alk3 and Id1. Nineteen mice survive the complete SCI and peripheral denervation procedure. When CTX injections were done right after surgery (n = 7), bilateral HO were detected in all animals after 28 days. Micro-CT measurements showed significantly increased BV in denervated paws (1.47 mm3 +/- 0.5) compared to contralateral sides (0.56 mm3 +/-0.4), p = 0.03. When peripheral denervation and CTX injections were performed after sham SCI surgery (n = 6), bilateral HO were present in three mice at day 28. Quantitative PCR analyses showed no changes in intra muscular BMP2 expression after SCI as compared to control mice (shamSCI). Peripheral denervation can be reliably added to spinal cord transection in NHO mouse model. This new experimental design confirms that neuro inflammatory mechanisms induced by central or peripheral nervous system injury plays a key role in triggering ectopic osteogenesis.

Expression of BMP-2 in Vascular Endothelial Cells of Recipient May Predict Delayed Graft Function After Renal Transplantation.

BACKGROUND/AIMS: Delayed graft function (DGF) is associated with adverse outcomes after renal transplantation. Bone morphogenetic protein-2 (BMP-2) is involved in both endothelial function and immunological events. We compared expression of BMP-2 in epigastric artery of renal transplant recipients with immediate graft function (IGF) and DGF. METHODS: 79 patients were included in this prospective study. Patients were divided in IGF group (64 patients) and DGF group (15 patients). BMP-2 expression in intima media (BMP2m) and endothelium (BMP2e) of epigastric artery was assessed by immunohistochemistry. RESULTS: Lower intensity of BMP2e staining was recorded in DGF compared to IGF. In DGF patients, 93% had no expression of BMP2e and 7% had 1st grade expression, compared to 45% and 41% in IGF group, respectively (P=0.001) (P<0.001 for no expression and P = 0.015 for 1st grade expression). Patients who had BMP2e staining positive had lower odds for DGF (OR 0.059 [0.007, 0.477]) and this remained significant even after adjustment for donor and recipient variables, cold ischemia time, and immunological matching (OR 0.038 [0.003, 0.492]). CONCLUSIONS: Our results demonstrate that BMP-2 expression in endothelial cells of epigastric arteries may predict development of DGF.

Altered DNA Methylation of Long Noncoding RNA H19 in Calcific Aortic Valve Disease Promotes Mineralization by Silencing NOTCH1.

BACKGROUND: Calcific aortic valve disease is characterized by an abnormal mineralization of the aortic valve. Osteogenic activity in the aortic valve is under the control of NOTCH1, which regulates the expression of key pro-osteogenic genes such as RUNX2 and BMP2. Long noncoding RNAs (lncRNAs) may reprogram cells by altering the gene expression pattern. METHODS: Multidimensional genomic profiling was performed in human aortic valves to document the expression of lncRNAs and the DNA methylation pattern in calcific aortic valve disease. In-depth functional assays were carried out to document the impact of lncRNA on the mineralization of the aortic valve. RESULTS: We documented that lncRNA H19 (H19) was increased in calcific aortic valve disease. Hypomethylation of the promoter region was observed in mineralized aortic valves and was inversely associated with H19 expression. Knockdown and overexpression experiments showed that H19 induces a strong osteogenic phenotype by altering the NOTCH1 pathway. Gene promoter analyses showed that H19 silenced NOTCH1 by preventing the recruitment of p53 to its promoter. A knockdown of H19 in valve interstitial cells (VICs) increased the expression of NOTCH1 and decreased the level of RUNX2 and BMP2, 2 downstream targets repressed by NOTCH1. In rescue experiments, the transfection of a vector encoding for the active Notch intracellular domain prevented H19-induced mineralization of valve interstitial cells. CONCLUSIONS: These findings indicate that a dysregulation of DNA methylation in the promoter of H19 during calcific aortic valve disease is associated with a higher expression of this lncRNA, which promotes an osteogenic program by interfering with the expression of NOTCH1.

Growth Factors in Bone Marrow Blood of the Mandible With Application of Extracorporeal Shock Wave Therapy.

INTRODUCTION: Enhancement of bone regeneration is crucial to dental implantology. Growth factors play a significant role during osteogenesis and angiogenesis. Extracorporeal shock wave therapy (ESWT) enhances bone healing; however, no studies have yet been performed in oral implantology. MATERIALS AND METHODS: Twenty patients who underwent bilateral mandibular wisdom tooth removal were included. ESWT was applied to 1 side of the jaw. Blood samples were collected from the peripheral vein (PB), mandibular bone marrow without and with ESWT (BM-/+SW). Quantity and quality of the growth factors bone morphogenetic protein (BMP)-2, BMP-4, insulin-like growth factor 1 (IGF-1), vascular endothelial growth factor (VEGF), and transforming growth factor-beta (TGF-ß) were investigated via ELISA and cell proliferation assay. RESULTS: ELISA revealed superior amounts of IGF-1 and VEGF in BM-/+SW compared to PB (P < 0.05). TGF-ß demonstrated no variance. Levels of BMP-2 and BMP-4 were too low for adequate detection in the ELISA. No difference was noticed upon ESWT. The cell proliferation assay did not identify any changes comparing PB versus BM-SW versus BM + SW. CONCLUSION: IGF-1 and VEGF are present at higher levels in mandibular bone marrow than in peripheral blood (PB). This study did not identify any benefits of extracorporeal shock wave therapy to increase the investigated growth factors.