BACKGROUND

Increasingly, reports of frequent and occasionally catastrophic complications associated with use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in spinal fusion surgeries are being published. In the original peer review, industry-sponsored publications describing the use of rhBMP-2 in spinal fusion, adverse events of these types and frequency were either not reported at all or not reported to be associated with rhBMP-2 use. Some authors and investigators have suggested that these discrepancies were related to inadequate peer review and editorial oversight.

OBJECTIVE

To compare the conclusions regarding the safety and related efficacy published in the original rhBMP-2 industry-sponsored trials with subsequently available Food and Drug Administration (FDA) data summaries, follow-up publications, and administrative and organizational databases.

METHODS

Systematic review.

METHODS

Results and conclusions from original industry-sponsored rhBMP-2 publications regarding safety and related efficacy were compared with available FDA data summaries, follow-up publications, and administrative and organizational database analyses.

RESULTS

There were 13 original industry-sponsored rhBMP-2 publications regarding safety and efficacy, including reports and analyses of 780 patients receiving rhBMP-2 within prospective controlled study protocols. No rhBMP-2-associated adverse events (0%) were reported in any of these studies (99% confidence interval of adverse event rate <0.5%). The study designs of the industry-sponsored rhBMP-2 trials for use in posterolateral fusions and posterior lateral interbody fusion were found to have potential methodological bias against the control group. The reported morbidity of iliac crest donor site pain was also found to have serious potential design bias. Comparative review of FDA documents and subsequent publications revealed originally unpublished adverse events and internal inconsistencies. From this review, we suggest an estimate of adverse events associated with rhBMP-2 use in spine fusion ranging from 10% to 50% depending on approach. Anterior cervical fusion with rhBMP-2 has an estimated 40% greater risk of adverse events with rhBMP-2 in the early postoperative period, including life-threatening events. After anterior interbody lumbar fusion rates of implant displacement, subsidence, infection, urogenital events, and retrograde ejaculation were higher after using rhBMP-2 than controls. Posterior lumbar interbody fusion use was associated with radiculitis, ectopic bone formation, osteolysis, and poorer global outcomes. In posterolateral fusions, the risk of adverse effects associated with rhBMP-2 use was equivalent to or greater than that of iliac crest bone graft harvesting, and 15% to 20% of subjects reported early back pain and leg pain adverse events; higher doses of rhBMP-2 were also associated with a greater apparent risk of new malignancy.

CONCLUSIONS

Level I and Level II evidence from original FDA summaries, original published data, and subsequent studies suggest possible study design bias in the original trials, as well as a clear increased risk of complications and adverse events to patients receiving rhBMP-2 in spinal fusion. This risk of adverse events associated with rhBMP-2 is 10 to 50 times the original estimates reported in the industry-sponsored peer-reviewed publications.

Despite fluctuations in dietary iron intake and intermittent losses through bleeding, the plasma iron concentrations in humans remain stable at <em>10</em>-30 μM. While most of the iron entering blood plasma comes from recycling, appropriate amount of iron is absorbed from the diet to compensate for losses and maintain nontoxic amounts in stores. Plasma iron concentration and iron distribution are similarly regulated in laboratory rodents. The hepatic peptide hepcidin was identified as the systemic iron-regulatory hormone. In the efferent arc, hepcidin regulates intestinal iron absorption, plasma iron concentrations, and tissue iron distribution by inducing degradation of its receptor, the cellular iron exporter ferroportin. Ferroportin exports iron into plasma from absorptive enterocytes, from macrophages that recycle the iron of senescent erythrocytes, and from hepatocytes that store iron. In the more complex and less well understood afferent arc, hepatic hepcidin synthesis is transcriptionally regulated by extracellular and intracellular iron concentrations through a molecular complex of <em>bone</em> <em>morphogenetic</em> <em>protein</em> receptors and their iron-specific ligands, modulators and iron sensors. Through as yet undefined pathways, hepcidin is also homeostatically regulated by the iron requirements of erythroid precursors for hemoglobin synthesis. In accordance with the role of hepcidin-mediated iron redistribution in host defense, hepcidin production is regulated by inflammation as well. Increased hepcidin concentrations in plasma are pathogenic in iron-restrictive anemias including anemias associated with inflammation, chronic kidney disease and some cancers. Hepcidin deficiency causes iron overload in hereditary hemochromatosis and ineffective erythropoiesis. Hepcidin, ferroportin and their regulators represent potential targets for the diagnosis and treatment of iron disorders and anemias. This article is part of a Special Issue entitled: Cell Biology of Metals.

<em>Bone</em> is formed by a series of complex events involving the mineralization of extracellular matrix <em>proteins</em> rigidly orchestrated by cells with specific functions of maintaining the integrity of the <em>bone</em>. <em>Bone</em>, similar to other calcified tissues, is an intimate composite of the organic (collagen and noncollagenous <em>proteins</em>) and inorganic or mineral phases. The <em>bone</em> mineral idealized as calcium hydroxyapatite, Ca<em>10</em> (PO4)(6)(OH)2, is a carbonatehydroxyapatite, approximated by the formula: (Ca,X)(<em>10</em>)(PO4,HPO4,CO3)(6)(OH,Y)2, where X are cations (magnesium, sodium, strontium ions) that can substitute for the calcium ions, and Y are anions (chloride or fluoride ions) that can substitute for the hydroxyl group. The current author presents a brief review of CaP biomaterials that now are used as grafts for <em>bone</em> repair, augmentation, or substitution. Commercially-available CaP biomaterials differ in origin (natural or synthetic), composition (hydroxyapatite, beta-tricalcium phosphate, and biphasic CaP), or physical forms (particulates, blocks, cements, coatings on metal implants, composites with polymers), and in physicochemical properties. CaP biomaterials have outstanding properties: similarity in composition to <em>bone</em> mineral; bioactivity (ability to form <em>bone</em> apatitelike material or carbonate hydroxyapatite on their surfaces), ability to promote cellular function and expression leading to formation of a uniquely strong <em>bone</em>-CaP biomaterial interface; and osteoconductivity (ability to provide the appropriate scaffold or template for <em>bone</em> formation). In addition, CaP biomaterials with appropriate three-dimensional geometry are able to bind and concentrate endogenous <em>bone</em> <em>morphogenetic</em> <em>proteins</em> in circulation, and may become osteoinductive (capable of osteogenesis), and can be effective carriers of <em>bone</em> cell seeds. Therefore, CaP biomaterials potentially are useful in tissue engineering for regeneration of hard tissues.

The differentiation capacity of human embryonic stem cells (hESCs) holds great promise for therapeutic applications. We report a novel three-stage method to efficiently direct the differentiation of human embryonic stem cells into hepatic cells in serum-free medium. Human ESCs were first differentiated into definitive endoderm cells by 3 days of Activin A treatment. Next, the presence of fibroblast growth factor-4 and <em>bone</em> <em>morphogenetic</em> <em>protein</em>-2 in the culture medium for 5 days induced efficient hepatic differentiation from definitive endoderm cells. Approximately 70% of the cells expressed the hepatic marker albumin. After <em>10</em> days of further in vitro maturation, these cells expressed the adult liver cell markers tyrosine aminotransferase, tryptophan oxygenase 2, phosphoenolpyruvate carboxykinase (PEPCK), Cyp7A1, Cyp3A4 and Cyp2B6. Furthermore, these cells exhibited functions associated with mature hepatocytes including albumin secretion, glycogen storage, indocyanine green, and low-density lipo<em>protein</em> uptake, and inducible cytochrome P450 activity. When transplanted into CCl4 injured severe combined immunodeficiency mice, these cells integrated into the mouse liver and expressed human alpha-1 antitrypsin for at least 2 months. In addition, we found that the hESC-derived hepatic cells were readily infected by human immunodeficiency virus-hepatitis C virus pseudotype viruses.

CONCLUSIONS

We have developed an efficient way to direct the differentiation of human embryonic stem cells into cells that exhibit characteristics of mature hepatocytes. Our studies should facilitate searching the molecular mechanisms underlying human liver development, and form the basis for hepatocyte transplantation and drug tests.

One approach to resolving the complexities of chondrogenesis is to examine simplified systems in vitro. We analyzed cartilage differentiation by human adult stem cells from <em>bone</em> marrow stroma. Marrow stromal cells were cultured as micromass pellets for 21 days in serum-free medium containing transforming growth factor (TGF)-beta3, dexamethasone, and <em>bone</em> <em>morphogenetic</em> <em>protein</em> (BMP)-6. Assays for pulse-labeled [3H]DNA and for total DNA indicated that there was little proliferation and a progressive loss of cells in the pellets. There were continuous increases in mRNAs for cartilage matrix (proteoglycans and COL2, -9, -<em>10</em>, and -11), receptors [fibroblast growth factor 2 (FGFR2) and parathyroid hormone-related peptide receptor (PTHrP-R)], and transcription factors (SOX5, -6, and -9) as demonstrated by histochemical and microarray assays. Reverse transcription-PCR assays for 11 mRNAs confirmed the microarray data. SOX4, vascular endothelial growth factor (VEGF), and matrix metallo<em>protein</em>ase 14 (MMP14) increased at day 1 and decreased thereafter, suggesting roles early in chondrogenesis. Also, forkhead, CD<em>10</em>, and MMP13 increased up to day 7 and decreased thereafter, suggesting roles in an intermediate stage of chondrogenesis. In addition, two collagens (COL3A1 and COL16A1), a signaling molecule (WNT11), a homeobox homolog (BAPX1), a receptor (IL-1R1), an IGFs modulator (IGFBP5), and a mettalo<em>protein</em>ase (MMP16) increased progressively up to about day 14, suggesting roles later in chondrogenesis. Our results indicate that the simplicity of the system makes it possible to define in detail the cellular and molecular events during chondrogenesis.

Chordin (Chd) is an abundant <em>protein</em> secreted by Spemann organizer tissue during gastrulation. Chd antagonizes signaling by mature <em>bone</em> <em>morphogenetic</em> <em>proteins</em> (BMPs) by blocking binding to their receptors. Recombinant Xenopus Chd binds to BMP-4 with high affinity (KD, 3 x <em>10</em>(-<em>10</em>) M), binding specifically to BMPs but not to activin or TGF-beta1. Chd <em>protein</em> is able to dorsalize mesoderm and to neuralize ectoderm in Xenopus gastrula explants at 1 nM. We propose that the noncell-autonomous effects of Spemann's organizer on dorsoventral patterning are executed in part by diffusible signals that directly bind to and neutralize ventral BMPs during gastrulation.

Fractures are the most common large-organ, traumatic injuries to humans. The repair of <em>bone</em> fractures is a postnatal regenerative process that recapitulates many of the ontological events of embryonic skeletal development. Although fracture repair usually restores the damaged skeletal organ to its pre-injury cellular composition, structure and biomechanical function, about <em>10</em>% of fractures will not heal normally. This article reviews the developmental progression of fracture healing at the tissue, cellular and molecular levels. Innate and adaptive immune processes are discussed as a component of the injury response, as are environmental factors, such as the extent of injury to the <em>bone</em> and surrounding tissue, fixation and the contribution of vascular tissues. We also present strategies for fracture treatment that have been tested in animal models and in clinical trials or case series. The biophysical and biological basis of the molecular actions of various therapeutic approaches, including recombinant human <em>bone</em> <em>morphogenetic</em> <em>proteins</em> and parathyroid hormone therapy, are also discussed.

Cells from fetal or neonatal skeleton can synthesize <em>bone</em>-like tissue in vitro. In contrast, formation of <em>bone</em>-like tissue in vitro by cells derived from adult animals has rarely been reported and has not been achieved using cells from <em>bone</em> marrow. We have explored development of <em>bone</em>-like tissue in vitro by <em>bone</em> marrow stromal cells. Marrow stromal cells obtained from 40-43-day-old Wistar rats were grown in primary culture for 7 days and then subcultured for 20-30 days. Cells were cultured in either alpha-minimal essential medium containing 15% fetal bovine serum, antibiotics, and 50 micrograms/ml ascorbic acid, or the above medium supplemented with either <em>10</em> mM Na-beta-glycerophosphate, <em>10</em>(-8) M dexamethasone, or a combination of both. Cultures were examined using phase-contrast microscopy, undemineralized and demineralized tissue histology, histochemistry (for alkaline phosphatase activity), immunohistochemistry (for collagen type, osteonectin, and <em>bone</em> Gla-<em>protein</em>), scanning and transmission electron microscopy, energy dispersive X-ray microanalysis, and X-ray diffraction. Collagenous, mineralized nodules exhibiting morphological and ultrastructural characteristics similar to <em>bone</em> were formed in the cultures, but only in the presence of both beta-glycerophosphate and dexamethasone. Cells associated with the nodules exhibited alkaline phosphatase activity. The matrix of the nodules was composed predominantly of type-I collagen and both osteonectin and Gla-<em>protein</em> were present. X-ray microanalysis showed the presence of Ca and P, and X-ray diffraction indicated the mineral to be hydroxyapatite. The nodules were also examined for <em>bone</em> <em>morphogenetic</em> <em>protein</em>-like activity. Paired diffusion chambers containing partly demineralized nodules and fetal muscle were implanted intraperitonealy in rats. Induction of cartilage in relation to muscle was observed histologically after 40 days in the chambers. This finding provided further support for the <em>bone</em>-like nature of the nodules. The observations show that <em>bone</em>-like tissue can be synthesized in vitro by cells cultured from young-adult <em>bone</em> marrow, provided that the medium contains both beta-glycerophosphate and, particularly, dexamethasone.

Human embryonic stem cells (hESCs) randomly differentiate into multiple cell types during embryoid body (EB) development. To date, characterization of specific factors capable of influencing hematopoietic cell fate from hESCs remains elusive. Here, we report that the treatment of hESCs during EB development with a combination of cytokines and <em>bone</em> <em>morphogenetic</em> <em>protein</em>-4 (BMP-4), a ventral mesoderm inducer, strongly promotes hematopoietic differentiation. Hematopoietic progenitors of multiple lineages were generated from EBs and were found to be restricted to the population of progeny expressing cell surface CD45. Addition of BMP-4 had no statistically significant effect on hematopoietic differentiation but enabled significant enhancement in progenitor self-renewal, independent of cytokine treatment. Hematopoietic commitment was characterized as the temporal emergence of single CD45+ cells first detectable after day <em>10</em> of culture and was accompanied by expression of hematopoietic transcription factors. Despite the removal of cytokines at day <em>10</em>, hematopoietic differentiation of hESCs continued, suggesting that cytokines act on hematopoietic precursors as opposed to differentiated hematopoietic cells. Our study establishes the first evidence for the role of cytokines and BMP-4 in promoting hematopoietic differentiation of hESC lines and provides an unprecedented system to study early developmental events that govern the initiation of hematopoiesis in the human.

Generation of hepatocytes from human embryonic stem cells (hESCs) could represent an advantageous source of cells for cell therapy approaches as an alternative to orthotopic liver transplantation. However, the generation of differentiated hepatocytes from hESCs remains a major challenge, especially using a method compatible with clinical applications. We report a novel approach to differentiate hESCs into functional hepatic cells using fully defined culture conditions, which recapitulate essential stages of liver development. hESCs were first differentiated into a homogenous population of endoderm cells using a combination of activin, fibroblast growth factor 2, and <em>bone</em> <em>morphogenetic</em> <em>protein</em> 4 together with phosphoinositide 3-kinase inhibition. The endoderm cells were then induced to differentiate further into hepatic progenitors using fibroblast growth factor <em>10</em>, retinoic acid, and an inhibitor of activin/nodal receptor. After further maturation, these cells expressed markers of mature hepatocytes, including asialoglyco<em>protein</em> receptor, tyrosine aminotransferase, alpha1-antitrypsin, Cyp7A1, and hepatic transcription factors such as hepatocyte nuclear factors 4alpha and 6. Furthermore, the cells generated under these conditions exhibited hepatic functions in vitro, including glycogen storage, cytochrome activity, and low-density lipo<em>protein</em> uptake. After transduction with a green fluorescent <em>protein</em>-expressing lentivector and transplantation into immunodeficient uPA transgenic mice, differentiated cells engrafted into the liver, grew, and expressed human albumin and alpha1-antitrypsin as well as green fluorescent <em>protein</em> for at least 8 weeks. In addition, we showed that hepatic cells could be generated from human-induced pluripotent cells derived from reprogrammed fibroblasts, demonstrating the efficacy of this approach with pluripotent stem cells of diverse origins.

CONCLUSIONS

We have developed a robust and efficient method to differentiate pluripotent stem cells into hepatic cells, which exhibit characteristics of human hepatocytes. Our approach should facilitate the development of clinical grade hepatocytes for transplantation and for research on drug discovery.

Morphogenesis of the mouse lung involves reciprocal interactions between the epithelial endoderm and the surrounding mesenchyme, leading to an invariant early pattern of branching that forms the basis of the respiratory tree. There is evidence that Fibroblast growth factor <em>10</em> (Fgf<em>10</em>) and <em>Bone</em> <em>Morphogenetic</em> <em>Protein</em> 4 (Bmp4), expressed in the distal mesenchyme and endoderm, respectively, play important roles in branching morphogenesis. To examine these roles in more detail, we have exploited an in vitro culture system in which isolated endoderm is incubated in Matrigel(TM) substratum with Fgf-loaded beads. In addition, we have used a Bmp4(lacZ) line of mice in which lacZ faithfully reports Bmp4 expression. Analysis of lung endoderm in vivo shows a dynamic pattern of Bmp4(lacZ) expression during bud outgrowth, extension and branching. In vitro, Fgf<em>10</em> induces both proliferation and chemotaxis of isolated endoderm, whether it is derived from the distal or proximal lung. Moreover, after 48 hours, Bmp4(lacZ) expression is upregulated in the endoderm closest to the bead. Addition of 30-50 ng/ml of exogenous purified Bmp4 to the culture medium inhibits Fgf-induced budding or chemotaxis, and inhibits overall proliferation. By contrast, the Bmp-binding <em>protein</em> Noggin enhances Fgf-induced morphogenesis. Based on these and other results, we propose a model for the combinatorial roles of Fgf<em>10</em> and Bmp4 in branching morphogenesis of the lung.

During cardiogenesis, perturbation of a key transition at mid-gestation from cardiac patterning to cardiac growth and chamber maturation often leads to diverse types of congenital heart disease, such as ventricular septal defect (VSD), myocardium noncompaction, and ventricular hypertrabeculation. This transition, which occurs at embryonic day (E) 9.0-9.5 in murine embryos and E24-28 in human embryos, is crucial for the developing heart to maintain normal cardiac growth and function in response to an increasing hemodynamic load. Although, ventricular trabeculation and compaction are key <em>morphogenetic</em> events associated with this transition, the molecular and cellular mechanisms are currently unclear. Initially, cardiac restricted cytokine <em>bone</em> <em>morphogenetic</em> <em>protein</em> <em>10</em> (BMP<em>10</em>) was identified as being upregulated in hypertrabeculated hearts from mutant embryos deficient in FK506 binding <em>protein</em> 12 (FKBP12). To determine the biological function of BMP<em>10</em> during cardiac development, we generated BMP<em>10</em>-deficient mice. Here we describe an essential role of BMP<em>10</em> in regulating cardiac growth and chamber maturation. BMP<em>10</em> null mice display ectopic and elevated expression of p57(kip2) and a dramatic reduction in proliferative activity in cardiomyocytes at E9.0-E9.5. BMP<em>10</em> is also required for maintaining normal expression levels of several key cardiogenic factors (e.g. NKX2.5 and MEF2C) in the developing myocardium at mid-gestation. Furthermore, BMP<em>10</em>-conditioned medium is able to rescue BMP<em>10</em>-deficient hearts in culture. Our data suggest an important pathway that involves a genetic interaction between BMP<em>10</em>, cell cycle regulatory <em>proteins</em> and several major cardiac transcription factors in orchestrating this transition in cardiogenesis at mid-gestation. This may provide an underlying mechanism for understanding the pathogenesis of both structural and functional congenital heart defects.

BACKGROUND

Most patients with familial primary pulmonary hypertension have defects in the gene for bone morphogenetic protein receptor II (BMPR2), a member of the transforming growth factor beta (TGF-beta) superfamily of receptors. Because patients with hereditary hemorrhagic telangiectasia may have lung disease that is indistinguishable from primary pulmonary hypertension, we investigated the genetic basis of lung disease in these patients.

METHODS

We evaluated members of five kindreds plus one individual patient with hereditary hemorrhagic telangiectasia and identified 10 cases of pulmonary hypertension. In the two largest families, we used microsatellite markers to test for linkage to genes encoding TGF-beta-receptor proteins, including endoglin and activin-receptor-like kinase 1 (ALK1), and BMPR2. In subjects with hereditary hemorrhagic telangiectasia and pulmonary hypertension, we also scanned ALK1 and BMPR2 for mutations.

RESULTS

We identified suggestive linkage of pulmonary hypertension with hereditary hemorrhagic telangiectasia on chromosome 12q13, a region that includes ALK1. We identified amino acid changes in activin-receptor-like kinase 1 that were inherited in subjects who had a disorder with clinical and histologic features indistinguishable from those of primary pulmonary hypertension. Immunohistochemical analysis in four subjects and one control showed pulmonary vascular endothelial expression of activin-receptor-like kinase 1 in normal and diseased pulmonary arteries.

CONCLUSIONS

Pulmonary hypertension in association with hereditary hemorrhagic telangiectasia can involve mutations in ALK1. These mutations are associated with diverse effects, including the vascular dilatation characteristic of hereditary hemorrhagic telangiectasia and the occlusion of small pulmonary arteries that is typical of primary pulmonary hypertension.

In the aorta, diabetes activates an osteogenic program that includes expression of <em>bone</em> <em>morphogenetic</em> <em>protein</em>-2 (BMP2) and the osteoblast homeo<em>protein</em> Msx2. To evaluate BMP2-Msx2 signaling in vascular calcification, we studied primary aortic myofibroblasts. These cells express vascular smooth muscle cell (VSMC) markers, respond to BMP2 by up-regulating Msx2, and undergo osteogenic differentiation with BMP2 treatment or transduction with a virus encoding Msx2. The osteoblast factor osterix (Osx) is up-regulated <em>10</em>-fold by Msx2, but Runx2 mRNA is unchanged; the early osteoblast marker alkaline phosphatase increases 50-fold with mineralized nodule formation enhanced 30-fold. Adipocyte markers are concomitantly suppressed. To better understand Msx2 actions on osteogenesis versus adipogenesis, mechanistic studies were extended to C3H<em>10</em>T1/2 mesenchymal cells. Msx2 enhances osteogenic differentiation in synergy with BMP2. Osteogenic actions depend upon intrinsic Msx2 DNA binding; the gain-of-function variant Msx2(P148H) directs enhanced mineralization, whereas the binding-deficient variant Msx2(T147A) is inactive. Adipogenesis (lipid accumulation, Pparg expression) is inhibited by Msx2. By contrast, suppression of adipogenesis does not require Msx2 DNA binding; inhibition occurs in part via <em>protein</em>-<em>protein</em> interactions with C/EBPalpha that control Pparg transcription. Thus, Msx2 regulates osteogenic versus adipogenic differentiation of aortic myofibroblasts. Myofibroblasts capable of both fates can be diverted to the osteogenic lineage by BMP2-Msx2 signaling and contribute to vascular calcification.

BACKGROUND

Mutations in the type II receptor for bone morphogenetic protein (BMPR-II), a receptor member of the transforming growth factor-beta (TGF-beta) superfamily, underlie many cases of familial and sporadic primary pulmonary hypertension (PPH). We postulated that pulmonary artery smooth muscle cells (PASMCs) from patients with PPH might demonstrate abnormal growth responses to TGF-beta superfamily members.

RESULTS

For studies of (3)H-thymidine incorporation or cell proliferation, PASMCs (passages 4 to 8) were derived from main pulmonary arteries. In control cells, 24-hour incubation with TGF-beta(1) (10 ng/mL) or bone morphogenetic protein (BMP)-2, -4, and -7 (100 ng/mL) inhibited basal and serum-stimulated (3)H-thymidine incorporation, and TGF-beta(1) and BMPs inhibited the proliferation of serum-stimulated PASMCs. In contrast, TGF-beta(1) stimulated (3)H-thymidine incorporation (200%; P<0.001) and cell proliferation in PASMCs from PPH but not from patients with secondary pulmonary hypertension. In addition, BMPs failed to suppress DNA synthesis and proliferation in PASMCs from PPH patients. Reverse transcription-polymerase chain reaction of PASMC mRNA detected transcripts for type I (TGF-betaRI, Alk-1, ActRI, and BMPRIB) and type II (TGF-betaRII, BMPR-II, ActRII, ActRIIB) receptors. Receptor binding and cross-linking studies with (125)I-TGF-beta(1) confirmed that the abnormal responses in PPH cells were not due to differences in TGF-beta receptor binding. Mutation analysis of PASMC DNA failed to detect mutations in TGF-betaRII and Alk-1 but confirmed the presence of a mutation in BMPR-II in 1 of 5 PPH isolates.

CONCLUSIONS

We conclude that PASMCs from patients with PPH exhibit abnormal growth responses to TGF-beta(1) and BMPs and that altered integration of TGF-beta superfamily growth signals may contribute to the pathogenesis of PPH.

METHODS

A prospective randomized clinical study was conducted.

OBJECTIVE

To determine whether the dose and carrier that were successful in rhesus monkeys could induce consistent radiographic spine fusion in humans.

BACKGROUND

Preclinical studies have demonstrated that recombinant human bone morphogenetic protein-2 (rhBMP-2), an osteoinductive bone morphogenetic protein, is successful at generating spine fusion in rabbits and rhesus monkeys.

METHODS

For this study, 25 patients undergoing lumbar arthrodesis were randomized (1:2:2 ratio) based on the arthrodesis technique: autograft/Texas Scottish Rite Hospital (TSRH) pedicle screw instrumentation (n = 5), rhBMP-2/TSRH (n = 11), and rhBMP-2 only without internal fixation (n = 9). On each side, 20 mg of rhBMP-2 were delivered on a carrier consisting of 60% hydroxyapatite and 40% tricalcium phosphate granules (10 cm /side). The patients had single-level disc degeneration, Grade 1 or less spondylolisthesis, mechanical low back pain with or without leg pain, and at least 6 months failure of nonoperative treatment.

RESULTS

All 25 patients were available for follow-up evaluation (mean, 17 months; range 12-27 months). The radiographic fusion rate was 40% (2/5) in the autograft/TSRH group and 100% (20/20) with rhBMP-2 group with or without TSRH internal fixation ( = 0.004). A statistically significant improvement in Oswestry score was seen at 6 weeks in the rhBMP-2 only group (-17.6; = 0.009), and at 3 months in the rhBMP-2/TSRH group (-17.0; = 0.003), but not until 6 months in the autograft/TSRH group (-17.3; = 0.041). At the final follow-up assessment, Oswestry improvement was greatest in the rhBMP-2 only group (-28.7, < 0.001). The SF-36 Pain Index and PCS subscales showed similar changes.

CONCLUSIONS

This pilot study is the first with at least 1 year of follow-up evaluation to demonstrate successful posterolateral spine fusion using a BMP-based bone graft substitute, with radiographs and CT scans as the determinant. Consistently, rhBMP-2 was able to induce bone in the posterolateral lumbar spine when delivered at a dose of 20 mg per side with or without the use of internal fixation. Patients with spondylolisthesis classified higher than Meyerding Grade 1 or with more than 5 mm of translational motion may still require internal fixation. Some patients did smoke during the postoperative period, and all in the rhBMP-2 groups still obtained solid fusions.

CONCLUSIONS

Consistently, rhBMP-2 with the biphasic calcium phosphate granules induced radiographic posterolateral lumbar spine fusion with or without internal fixation in patients whose spondylolisthesis did not exceed Grade 1. Statistically greater and quicker improvement in patient-derived clinical outcome was measured in the rhBMP-2 groups.

The pulmonary arteries (PA) in pulmonary arterial hypertension (PAH) are constricted and remodeled;. They have suppressed apoptosis, partly attributable to suppression of the <em>bone</em> <em>morphogenetic</em> <em>protein</em> axis and selective downregulation of PA smooth muscle cell (PASMC) voltage-gated K+ channels, including Kv1.5. The Kv downregulation-induced increase in [K+]i, tonically inhibits caspases, further suppressing apoptosis. Mitochondria control apoptosis and produce activated oxygen species like H2O2, which regulate vascular tone by activating K+ channels, but their role in PAH is unknown. We show that dichloroacetate (DCA), a metabolic modulator that increases mitochondrial oxidative phosphorylation, prevents and reverses established monocrotaline-induced PAH (MCT-PAH), significantly improving mortality. Compared with MCT-PAH, DCA-treated rats (80 mg/kg per day in drinking water on day 14 after MCT, studied on day 21) have decreased pulmonary, but not systemic, vascular resistance (63% decrease, P<0.002), PA medial thickness (28% decrease, P<0.0001), and right ventricular hypertrophy (34% decrease, P<0.001). DCA is similarly effective when given at day 1 or day 21 after MCT (studied day 28) but has no effect on normal rats. DCA depolarizes MCT-PAH PASMC mitochondria and causes release of H2O2 and cytochrome c, inducing a <em>10</em>-fold increase in apoptosis within the PA media (TUNEL and caspase 3 activity) and decreasing proliferation (proliferating-cell nuclear antigen and BrdU assays). Immunoblots, immunohistochemistry, laser-captured microdissection-quantitative reverse-transcription polymerase chain reaction and patch-clamping show that DCA reverses the Kv1.5 downregulation in resistance PAs. In summary, DCA reverses PA remodeling by increasing the mitochondria-dependent apoptosis/proliferation ratio and upregulating Kv1.5 in the media. We identify mitochondria-dependent apoptosis as a potential target for therapy and DCA as an effective and selective treatment for PAH.

The neural crest is a stem population critical for development of the vertebrate craniofacial skeleton and peripheral ganglia. Neural crest cells originate along the border between the neural plate and epidermis, migrate extensively and generate numerous derivatives, including neurons and glia of the peripheral nervous system, melanocytes, <em>bone</em> and cartilage of the head skeleton. Impaired neural crest development is associated with human defects, including cleft palate. Classically, the neural crest has been thought to form by interactions at the border between neural and non-neural ectoderm or mesoderm, and defined factors such as <em>bone</em> <em>morphogenetic</em> <em>proteins</em> (BMPs) and Wnt <em>proteins</em> have been postulated as neural crest-inducers. Although competence to induce crest cells declines after stage <em>10</em> (ref. 14), little is known about when neural crest induction begins in vivo. Here we report that neural crest induction is underway during gastrulation and well before proper neural plate appearance. We show that a restricted region of chick epiblast (stage 3-4) is specified to generate neural crest cells when explanted under non-inducing conditions. This region expresses the transcription factor Pax7 by stage 4 + and later contributes to neural folds and migrating neural crest. In chicken embryos, Pax7 is required for neural crest formation in vivo, because blocking its translation inhibits expression of the neural crest markers Slug, Sox9, Sox<em>10</em> and HNK-1. Our results indicate that neural crest specification initiates earlier than previously assumed, independently of mesodermal and neural tissues, and that Pax7 has a crucial function during neural crest development.

The murine Foxf1 gene, encoding a forkhead - or winged helix - transcription factor, is expressed in splanchnic mesenchyme during organogenesis. The concentration of expression to subepithelial mesenchyme suggested that Foxf1 is activated by paracrine signals from endodermal epithelia. Homozygous Foxf1-null mice die before embryonic day <em>10</em>, owing to defects in extra-embryonic mesoderm, and do not provide any information about the role of Foxf1 in morphogenesis of endodermally derived organs. We show that, on CD1 genetic background, Foxf1 heterozygote perinatal mortality is around 90%. The haploinsufficiency causes a variable phenotype that includes lung immaturity and hypoplasia, fusion of right lung lobes, narrowing of esophagus and trachea, esophageal atresia and tracheo-esophageal fistula. Similar malformations are observed in mutants that are defective in the sonic hedgehog (Shh) signaling pathway, and we show that exogenous Shh activates transcription of Foxf1 in developing lung. Foxf1 mRNA is absent in the lungs, foregut and sclerotomes of Shh(-/-) embryos, but persists in tissues where indian hedgehog (Ihh) is expressed. In lung organ cultures, activation of Foxf1 by Shh is counteracted by <em>bone</em> <em>morphogenetic</em> <em>protein</em> 4 (BMP4). Fibroblast growth factor (FGF) <em>10</em> and FGF7 both decrease Foxf1 expression and we speculate that this is mediated by transcriptional activation of epithelial Bmp4 (in the case of FGF<em>10</em>) and by inhibition of Shh expression for FGF7.

Although growth factors naturally exert their <em>morphogenetic</em> influences within the context of the extracellular matrix microenvironment, the interactions among growth factors, their receptors, and other extracellular matrix components are typically ignored in clinical delivery of growth factors. We present an approach for engineering the cellular microenvironment to greatly accentuate the effects of vascular endothelial growth factor-A (VEGF-A) and platelet-derived growth factor-BB (PDGF-BB) for skin repair, and of <em>bone</em> <em>morphogenetic</em> <em>protein</em>-2 (BMP-2) and PDGF-BB for <em>bone</em> repair. A multifunctional recombinant fragment of fibronectin (FN) was engineered to comprise (i) a factor XIIIa substrate fibrin-binding sequence, (ii) the 9th to <em>10</em>th type III FN repeat (FN III9-<em>10</em>) containing the major integrin-binding domain, and (iii) the 12th to 14th type III FN repeat (FN III12-14), which binds growth factors promiscuously, including VEGF-A165, PDGF-BB, and BMP-2. We show potent synergistic signaling and morphogenesis between α5β1 integrin and the growth factor receptors, but only when FN III9-<em>10</em> and FN III12-14 are proximally presented in the same polypeptide chain (FN III9-<em>10</em>/12-14). The multifunctional FN III9-<em>10</em>/12-14 greatly enhanced the regenerative effects of the growth factors in vivo in a diabetic mouse model of chronic wounds (primarily through an angiogenic mechanism) and in a rat model of critical-size <em>bone</em> defects (through a mesenchymal stem cell recruitment mechanism) at doses where the growth factors delivered within fibrin only had no significant effects.

Pulmonary arterial hypertension (PAH) is a rare disorder that may be hereditable (HPAH), idiopathic (IPAH), or associated with either drug-toxin exposures or other medical conditions. Familial cases have long been recognized and are usually due to mutations in the <em>bone</em> <em>morphogenetic</em> <em>protein</em> receptor type 2 gene (BMPR2), or, much less commonly, 2 other members of the transforming growth factor-beta superfamily, activin-like kinase-type 1 (ALK1) and endoglin (ENG), which are associated with hereditary hemorrhagic telangiectasia. In addition, approximately 20% of patients with IPAH carry mutations in BMPR2. We provide a summary of BMPR2 mutations associated with HPAH, most of which are unique to each family and are presumed to result in loss of function. We review the finding of missense variants and variants of unknown significance in BMPR2 in IPAH/HPAH, fenfluramine exposure, and PAH associated with congenital heart disease. Clinical testing for BMPR2 mutations is available and may be offered to HPAH and IPAH patients but should be preceded by genetic counseling, since lifetime penetrance is only <em>10</em>% to 20%, and there are currently no known effective preventative measures. Identification of a familial mutation can be valuable in reproductive planning and identifying family members who are not mutation carriers and thus will not require lifelong surveillance. With advances in genomic technology and with international collaborative efforts, genome-wide association studies will be conducted to identify additional genes for HPAH, genetic modifiers for BMPR2 penetrance and genetic susceptibility to IPAH. In addition, collaborative studies of BMPR2 mutation carriers should enable identification of environmental modifiers, biomarkers for disease development and progression, and surrogate markers for efficacy end points in clinical drug development, thereby providing an invaluable resource for trials of PAH prevention.

The major Food and Drug Association-approved osteoinductive factors in wide clinical use are <em>bone</em> <em>morphogenetic</em> <em>proteins</em> (BMPs). Although BMPs can promote robust <em>bone</em> formation, they also induce adverse clinical effects, including cyst-like <em>bone</em> formation and significant soft tissue swelling. In this study, we evaluated multiple BMP2 doses in a rat femoral segmental defect model and in a minimally traumatic rat femoral onlay model to determine its dose-dependent effects. Results of our femoral segmental defect model established a low BMP2 concentration range (5 and <em>10</em> μg/mL, total dose 0.375 and 0.75 μg in 75 μg total volume) unable to induce defect fusion, a mid-range BMP2 concentration range able to fuse the defect without adverse effects (30 μg/mL, total dose 2.25 μg in 75 μg total volume), and a high BMP2 concentration range (150, 300, and 600 μg/mL, total dose 11.25, 22.5, and 45 μg in 75 μg total volume) able to fuse the defect, but with formation of cyst-like bony shells filled with histologically confirmed adipose tissue. In addition, compared to control, 4 mg/mL BMP2 also induced significant tissue inflammatory infiltrates and exudates in the femoral onlay model that was accompanied by increased numbers of osteoclast-like cells at 3, 7, and 14 days. Overall, we consistently reproduced BMP2 side effects of cyst-like <em>bone</em> and soft tissue swelling using high BMP2 concentration approaching the typical human 1500 μg/mL.

Genome-wide association studies (GWAS) have identified 14 tagging single nucleotide polymorphisms (tagSNPs) that are associated with the risk of colorectal cancer (CRC), and several of these tagSNPs are near <em>bone</em> <em>morphogenetic</em> <em>protein</em> (BMP) pathway loci. The penalty of multiple testing implicit in GWAS increases the attraction of complementary approaches for disease gene discovery, including candidate gene- or pathway-based analyses. The strongest candidate loci for additional predisposition SNPs are arguably those already known both to have functional relevance and to be involved in disease risk. To investigate this proposition, we searched for novel CRC susceptibility variants close to the BMP pathway genes GREM1 (15q13.3), BMP4 (14q22.2), and BMP2 (20p12.3) using sample sets totalling 24,9<em>10</em> CRC cases and 26,275 controls. We identified new, independent CRC predisposition SNPs close to BMP4 (rs1957636, P = 3.93×<em>10</em>(-<em>10</em>)) and BMP2 (rs4813802, P = 4.65×<em>10</em>(-11)). Near GREM1, we found using fine-mapping that the previously-identified association between tagSNP rs4779584 and CRC actually resulted from two independent signals represented by rs16969681 (P = 5.33×<em>10</em>(-8)) and rs11632715 (P = 2.30×<em>10</em>(-<em>10</em>)). As low-penetrance predisposition variants become harder to identify-owing to small effect sizes and/or low risk allele frequencies-approaches based on informed candidate gene selection may become increasingly attractive. Our data emphasise that genetic fine-mapping studies can deconvolute associations that have arisen owing to independent correlation of a tagSNP with more than one functional SNP, thus explaining some of the apparently missing heritability of common diseases.

Epidemiological studies suggest that Mediterranean diets rich in resveratrol are associated with reduced risk of coronary artery disease. However, the mechanisms by which resveratrol exerts its cardioprotective effects are not completely understood. Because TNF-alpha-induced endothelial activation and vascular inflammation play a critical role in vascular aging and atherogenesis, we evaluated whether resveratrol inhibits TNF-alpha-induced signal transduction in human coronary arterial endothelial cells (HCAECs). We found that TNF-alpha significantly increased adhesiveness of the monocytic THP-1 cells to HCAECs, an effect that could be inhibited by pretreatment with resveratrol and the NF-kappaB inhibitor pyrrolidine dithiocarbamate. Previously, we found that TNF-alpha activates NAD(P)H oxidases, and our recent data showed that TNF-alpha-induced endothelial activation was prevented by the NAD(P)H oxidase inhibitor apocynin or catalase plus SOD. Resveratrol also inhibited H(2)O(2)-induced monocyte adhesiveness. Using a reporter gene assay, we found that, in HCAECs, TNF-alpha significantly increased NF-kappaB activity, which could be inhibited by resveratrol (>50% inhibition at <em>10</em>(-6) mol/l) and pyrrolidine dithiocarbamate. Resveratrol also inhibited TNF-alpha-induced, NF-kappaB-driven luciferase expression in rat aortas electroporated with the reporter gene construct. In TNF-alpha-treated HCAECs, resveratrol (in the submicromolar range) significantly attenuated expression of NF-kappaB-dependent inflammatory markers inducible nitric oxide synthase, IL-6, <em>bone</em> <em>morphogenetic</em> <em>protein</em>-2, ICAM-1, and VCAM. Thus resveratrol at nutritionally relevant concentrations inhibits TNF-alpha-induced NF-kappaB activation and inflammatory gene expression and attenuates monocyte adhesiveness to HCAECs. We propose that these anti-inflammatory actions of resveratrol are responsible, at least in part, for its cardioprotective effects.