Gene Encoding Bone Morphogenetic Protein Research Articles

Clinical and hemodynamic phenotype of BMPR2 variation carriers with pulmonary arterial hypertension: A systematic review and a call to action

Background: Carriers of variations in the gene encoding bone morphogenetic protein receptor type 2 (BMPR2∆) are at high risk for severe pulmonary arterial hypertension (PAH+). Aim: To define the clinical and hemodynamic phenotype of BMPR2∆/PAH+ patients. Methods: We performed a systematic review encompassing observational data until July 2019 about BMPR2∆ and confirmed PAH diagnosis. According to international clinical guidelines, we aimed to determine the clinical and hemodynamic phenotype of BMPR2D/PAH+ patients. We also explored functional assessment and risk stratification. PROSPERO ID CRD42019124324. Results: We included 54 reports with 6,668 PAH+ patients, 1,220 were BMPR2∆/PAH+ with an allele frequency within studies ranging from 8.8% to 24.9%. Female sex was predominant, and age at diagnosis ranged from 32.2 to 46.2 years. We observed the occurrence of BMPR2∆ across all PAH clinical classifications, except for schistosomiasis. BMPR2∆ correlated with severity signs and symptoms in PAH, poor functional class, severe pulmonary hypertension with elevated pulmonary vascular resistance, and low cardiac index and output. The clinical and hemodynamic missing data ranged between 28%-49% and 50%-65%, respectively. Conclusion: BMPR2∆/PAH+ patients present a phenotype with high mortality risk. The clinical triad of dyspnea, syncope, and hemoptysis could suggest BMPR2∆/PAH+. However, poor clinical and hemodynamic characterization hinders translating the benefits of genomic analyses to the clinical setting.

BMPR2 variants in pulmonary arterial hypertension. Are they really worrisome?

Abstract Background Pulmonary arterial hypertension (PAH) is a rare and severe disease. The discovery of the gene encoding Bone Morphogenetic Protein Receptor Type 2 (BMPR2) in 2000 was the first evidence of an association between genetics and PAH. BMPR2 mutation carriers are younger and have higher haemodynamic severity, determining higher risk than sporadic cases. In the last few years, novel genetic variants have been identified. The risk of mortality of the currently known mutations is scarce. Purpose To describe the role of gene variants regarding long-term survival in a cohort of PAH patients. Methods We included patients diagnosed with PAH between January 2011-December 2020, following the ESC/ERC Guidelines recommendations. At least one genetic study was available in included individuals. Pulmonary venooclusive disease, PAH associated with congenital heart disease, or connective tissue disorders were excluded. Three groups were compared: no mutation, BMPR2 carriers and other genetic variants. Comparison of qualitative and quantitative variables was done by Chi-square test and ANOVA test, respectively. Crude and adjusted Log-rank test was performed for the evaluation of mortality. Results 361 were finally included. The most frequent gene variant was BMPR2. Among the eight other gene variants, there were 2 cases of KCKN3, 2 of ACVRL1, and 1 case of KCNA5, TBX4, CPS1, and GDF2. BMPR2 and the rest of mutation carriers were younger at diagnosis and had worse haemodynamic parameters than non-carriers. Nevertheless, these patients tended to perform higher distances in the 6-minute walk test. Interestingly, BMPR2 patients had higher DLCO values at diagnosis (table). After 104.1±77.2 months of follow-up, there was a tendency for BMPR2 carriers toward lower crude free survival of mortality or lung transplantation. Nevertheless, this survival benefit disappears when adjusted by age (Table, figure). Conclusions The diagnostic yields of genetic analysis for pathogenic or likely pathogenic variants in idiopathic PAH are approximately 11%. BMPR2 is the most frequent causal gene. These patients are associated with marked haemodynamic impairment. Nevertheless, its younger age probably determines the better long-term results regarding mortality or lung transplantation observed when comparing these results with sporadic patients or those carrying other mutations. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Rio Hortega grant. Instituto de Salud Carlos III (ISCIII), Ministry of Science and Innovation, Spanish Government.

The role of genomics and genetics in pulmonary arterial hypertension.

[No abstract. Showing first paragraph of article]Although pulmonary hypertension (PH) had been recognised for centuries, it was not until the invention of cardiac catheterisation in the 1950s that enabled an accurate gene encoding bone morphogenetic protein receptor type 2, in patients with familial and clinical diagnosis. The discovery of heterozygous germline mutations in BMPR2, the idiopathic forms of pulmonary arterial hypertension (PAH) was another breakthrough in understanding the disease and initiated a new era in care of patients with this condition.

The features of rare pathogenic BMPR2 variants in pulmonary arterial hypertension: Comparison between patients and reference population

BackgroundMutations in the gene encoding bone morphogenetic protein receptor type 2 (BMPR2) are the most common genetic risk factors underlying pulmonary arterial hypertension (PAH). However, the features of PAH-related BMPR2 rare variants remain unclear. We propose that the discrepancy of BMPR2 rare variants landscape between patients with PAH and reference population would be important to address the genetic background of PAH-related variants. MethodsWe genotyped BMPR2 rare variants in 670 Chinese patients with pulmonary arterial hypertension. The BMPR2 rare variants were screened in 10,508 reference people from two exome databases. ResultsThe prevalence of rare BMPR2 variants in patients with PAH was significantly higher compared to the reference population (21.5%, 144/670 vs 0.87%, 91/10508, p = 1.3 × 10−118). In patients with PAH, 49% of identified BMPR2 rare variants were loss-of-function or splicing. These BMPR2 rare variants were only observed in 1% of the reference population (p = 9.0 × 10−12). Arg491, which is absent in the reference population, represented as hot-spot site (14.6%, 21/144) in PAH patients. BMPR2 missense mutations in PAH patients were more likely distributed in extracellular ligand-binding domain (ECD, 29.7% vs 11.1%, p < 0.001). Compared with Non-PAH-related variations, PAH-related missense variants tend to alter the amino acid electric status (51.4% vs 23.3%, p < 0.001). ConclusionsBMPR2 variants located in extracellular ligand-binding domain or altered the amino acid electric status are more pathogenic.

Clinical characteristics and survival of Chinese patients diagnosed with pulmonary arterial hypertension who carry BMPR2 or EIF2KAK4 variants

BackgroundVariants in the gene encoding bone morphogenetic protein receptor type II (BMPR2) are the most common genetic cause of pulmonary arterial hypertension (PAH), whereas biallelic variants in the eukaryotic translation initiation factor 2 alpha kinase 4 gene (EIF2AK4) are described in pulmonary veno-occlusive disease/pulmonary capillary haemangiomatosis (PVOD/PCH). Racial background may influence the clinical characteristics of patients diagnosed with PAH or PVOD/PCH. Here, we compared the clinical characteristics and survival between patients with BMPR2 variants or EIF2AK4 variants in a Chinese population.MethodsHeterozygous variants in BMPR2 and homozygous or compound heterozygous biallelic EIF2AK4 variants predicted to be deleterious were identified as potentially causal. Clinical and radiological data were collected and analysed. The primary outcomes were death or lung transplantation. Hazard ratios (HRs) for death or transplantation associated with the presence of BMPR2 or biallelic EIF2AK4 variants were calculated using Cox proportional hazards models to analyse patient survival.ResultsTwo hundred thirty-two patients with PAH were enrolled for genetic testing, and PAH patients with associated conditions were excluded from the study. Forty-five patients with BMPR2 variants and 11 patients with biallelic EIF2AK4 variants were recruited. PAH patients with BMPR2 or biallelic EIF2AK4 variants presented symptoms at the ages of 25.57 ± 10.17 years and 31.6 ± 9.38 years, respectively. The whole group of patients showed female dominance either with BMPR2 variants or biallelic EIF2AK4 variants. Specific radiological abnormalities are more prominent in EIF2AK4 variant carriers but can also be found in some patients with BMPR2 variants. Biallelic EIF2AK4 variant carriers had worse survival than BMPR2 variant carriers (p < 0.0001).ConclusionsClinical pictures of PAH patients with BMPR2 and biallelic EIF2AK4 variants in the Chinese population differ from other populations by a younger age at diagnosis and demonstrate female dominance in the whole patient group. High-resolution chest CT can help assist in differentiating PAH with PVOD/PCH. BMPR2 variants and biallelic EIF2AK4 variants are associated with adverse outcomes, but the survival of patients with biallelic EIF2AK4 variants is dismal.

Screening strategies for pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is rare and, if untreated, has a median survival of 2–3 years. Pulmonary arterial hypertension may be idiopathic (IPAH) but is frequently associated with other conditions. Despite increased awareness, therapeutic advances, and improved outcomes, the time from symptom onset to diagnosis remains unchanged. The commonest symptoms of PAH (breathlessness and fatigue) are non-specific and clinical signs are usually subtle, frequently preventing early diagnosis where therapies may be more effective. The failure to improve the time to diagnosis largely reflects an inability to identify patients at increased risk of PAH using current approaches. To date, strategies to improve the time to diagnosis have focused on screening patients with a high prevalence [systemic sclerosis (10%), patients with portal hypertension assessed for liver transplantation (2–6%), carriers of mutations of the gene encoding bone morphogenetic protein receptor type II, and first-degree relatives of patients with heritable PAH]. In systemic sclerosis, screening algorithms have demonstrated that patients can be identified earlier, however, current approaches are resource intensive. Until, recently, it has not been considered possible to screen populations for rare conditions such as IPAH (prevalence 5–15/million/year). However, there is interest in the use of artificial intelligence approaches in medicine and the application of diagnostic algorithms to large healthcare data sets, to identify patients at risk of rare conditions. In this article, we review current approaches and challenges in screening for PAH and explore novel population-based approaches to improve detection.

BMP4 mutations in tooth agenesis and low bone mass

ObjectiveTo identify an uncommon genetic cause of tooth agenesis (TA) by utilizing whole exome sequencing (WES) and targeted Sanger sequencing in a cohort of 120 patients with isolated TA. DesignOne deleterious mutation in the gene encoding bone morphogenetic protein 4 (BMP4) was identified in 6 unrelated patients with TA by WES. After that, the coding exons of BMP4 were examined in 114 TA patients using Sanger sequencing. Dual-energy X-ray absorptiometry (DEXA) was used to measure the bone mineral density of patients who carried a BMP4 mutation. Finally, preliminary functional studies of two BMP4 mutants were performed. ResultsWe detected 3 novel missense mutations (c.58 G > A: p.Gly20Ser, c.326 G > T: p.Arg109Leu and c.614 T > C: p.Val205Ala) and 1 reported mutation in the BMP4 gene among 120 TA probands. The previously reported BMP4 mutation (c.751C > T: p.His251Tyr) was associated with urethra and eye anomalies. By extending the pedigrees, we determined that the tooth phenotypes had an autosomal dominant inheritance pattern, as individuals carrying a BMP4 mutation exhibit different types of dental anomalies. Interestingly, we observed that patients harboring a BMP4 mutation manifested early onset osteopenia or osteoporosis. Further in vitro functional assays demonstrated that two BMP4 mutants resulted in a decreased activation of Smad signaling. Therefore, a loss-of-function in BMP4 may contribute to the clinical phenotypes seen in this study. ConclusionsWe identified 4 mutations in the BMP4 gene in 120 TA patients. To our knowledge, this is the first study to describe human skeletal diseases associated with BMP4 mutations.

Bmpr2 Mutant Rats Develop Pulmonary and Cardiac Characteristics of Pulmonary Arterial Hypertension.

Monoallelic mutations in the gene encoding bone morphogenetic protein receptor 2 ( Bmpr2) are the main genetic risk factor for heritable pulmonary arterial hypertension (PAH) with incomplete penetrance. Several Bmpr2 transgenic mice have been reported to develop mild spontaneous PAH. In this study, we examined whether rats with the Bmpr2 mutation were susceptible to developing more severe PAH. The zinc finger nuclease method was used to establish rat lines with mutations in the Bmpr2 gene. These rats were then characterized at the hemodynamic, histological, electrophysiological, and molecular levels. Rats with a monoallelic deletion of 71 bp in exon 1 (Δ 71 rats) showed decreased BMPRII expression and phosphorylated SMAD1/5/9 levels. Δ 71 Rats develop age-dependent spontaneous PAH with a low penetrance (16%-27%), similar to that in humans. Δ 71 Rats were more susceptible to hypoxia-induced pulmonary hypertension than wild-type rats. Δ 71 Rats exhibited progressive pulmonary vascular remodeling associated with a proproliferative phenotype and showed lower pulmonary microvascular density than wild-type rats. Organ bath studies revealed severe alteration of pulmonary artery contraction and relaxation associated with potassium channel subfamily K member 3 (KCNK3) dysfunction. High levels of perivascular fibrillar collagen and pulmonary interleukin-6 overexpression discriminated rats that developed spontaneous PAH and rats that did not develop spontaneous PAH. Finally, detailed assessments of cardiomyocytes demonstrated alterations in morphology, calcium (Ca2+), and cell contractility specific to the right ventricle; these changes could explain the lower cardiac output of Δ 71 rats. Indeed, adult right ventricular cardiomyocytes from Δ 71 rats exhibited a smaller diameter, decreased sensitivity of sarcomeres to Ca2+, decreased [Ca2+] transient amplitude, reduced sarcoplasmic reticulum Ca2+ content, and short action potential duration compared with right ventricular cardiomyocytes from wild-type rats. We characterized the first Bmpr2 mutant rats and showed some of the critical cellular and molecular dysfunctions described in human PAH. We also identified the heart as an unexpected but potential target organ of Bmpr2 mutations. Thus, this new genetic rat model represents a promising tool to study the pathogenesis of PAH.

Use of Bone Morphogenetic Protein 15 Polymorphisms to Predict Ovarian Stimulation Outcomes in Infertile Brazilian Women.

Polymorphisms in the gene encoding bone morphogenetic protein 15 (BMP15) can result in inhibited secretion or lowered bioactivity of the BMP15 protein. BMP15 levels are associated with follicle-stimulating hormone receptor (FSHR) action on granulosa cells, wherein FSHR increases the sensitivity of ovarian follicles to follicle-stimulating hormone (FSH). In this study we evaluated the BMP15 polymorphisms A905 > G/rs3897937, C901 > T/rs17003221, and C-9 > G/rs3810682 in infertile Brazilian women in terms of anti-Mullerian hormone (AMH), FSH, and estradiol serum levels, as well as controlled ovarian hyperstimulation response and assisted reproduction outcomes. A cross-sectional study comprising 186 infertile women who underwent the first cycle of high complexity assisted reproduction treatment was conducted using the TaqMan assay for quantitative polymerase chain reaction genotyping. Serum AMH, FSH, and estradiol levels were measured by enzyme-linked immunosorbent assay. For C901 > T (rs17003221) carriers, there was a statistically significant difference among carriers of a polymorphic BMP15 genotype (TT) and the estradiol concentration. These women had higher estradiol levels than women who had homozygous wild type or heterozygous genotypes. There was also a positive correlation between serum AMH and the C-9 > G (rs3810682) polymorphism, wherein women carrying both polymorphic alleles (homozygous, GG) had higher average AMH levels than heterozygous women. However, none of the three polymorphisms studied showed a statistically significant correlation with assisted reproduction outcome. Oocytes are known to secrete factors that regulate follicular development and oocyte maturation. Abnormal expression of these factors may thus be involved in follicular development disorders. A recent study highlighted the importance of BMP15 in regulating ovulation rates in sheep and that heterozygous deletions in the -9C > G polymorphism reduced BMP15 concentrations, increased granulosa cell FHSR mRNA levels, elevated estrogen secretion, and activated production of stem cell factors. In this study we found that BMP15 polymorphisms affected estrogen and AMH levels. BMP15 polymorphisms are not correlated with ovarian stimulation and assisted reproduction outcomes in infertile Brazilian women.

BMP15 regulates the inhibin/activin system independently of ovulation rate control in sheep.

Polymorphisms in the gene encoding bone morphogenetic protein 15 (BMP15) have been associated with multiple ovulations in sheep. As BMP15 regulates inhibin expression in rodents, we assumed that the ovarian inhibin/activin system could mediate part of the effect of BMP15 mutations in the regulation of ovulation rate in sheep. To answer this question, we have studied the effects of two natural loss-of-function mutations of BMP15 on the expression of components of this system. The FecXR and the FecXGr mutations, when present respectively in Rasa Aragonesa ewes at the heterozygous state and in Grivette ewes at the homozygous state, were associated with a twofold increase in ovulation rate. There were only small differences between mutant and wild-type ewes for mRNA expression of INHA, INHBA, ACVR1B, ACVR2A, FST or TGFBR3 in granulosa cells and inhibin A or activin A concentrations in follicular fluid. Moreover, the effects of mutations differed between breeds. In cultures of granulosa cells from wild-type ewes, BMP15, acting alone or in synergy with GDF9, stimulated INHA, INHBA and FST expression, but inhibited the expression of TGFBR3 Activin A did not affect INHBA expression, but inhibited the expression of ACVR2A also. The complexity of the inhibin/activin system, including positive and antagonistic elements, and the differential regulation of these elements by BMP15 and activin can explain that the effects of BMP15 mutations differ when present in different genetic backgrounds. In conclusion, the ovarian inhibin/activin system is unlikely to participate in the increase of ovulation rate associated with BMP15 mutations in sheep.

Characterization of the Enhanced Bone Regenerative Capacity of Human Periodontal Ligament Stem Cells Engineered to Express the Gene Encoding Bone Morphogenetic Protein 2

Human periodontal ligament stem cells (hPDLSCs) are considered an appropriate cell source for therapeutic strategies. The aims of this study were to investigate the sustainability of bone morphogenetic protein 2 (BMP2) secretion and the bone regenerative capacity of hPDLSCs that had been genetically modified to express the gene encoding BMP2 (BMP2). hPDLSCs isolated from healthy third molars were transduced using replication-deficient recombinant adenovirus (rAd) encoding BMP2 (hPDLSCs/rAd-BMP2), and the cellular characteristics and osteogenic potentials of hPDLSCs/rAd-BMP2 were analyzed both in vitro and in vivo. hPDLSCs/rAd-BMP2 successfully secreted BMP2, formed colonies, and expressed immunophenotypes similar to their nontransduced counterparts. As to their osteogenic potential, hPDLSCs/rAd-BMP2 formed greater mineralized nodules and exhibited significantly higher levels of expression of BMP2 and the gene encoding alkaline phosphatase, and formed more and better quality bone than other hPDLSC-containing or recombinant human BMP2-treated groups, being localized at the initial site until 8 weeks. The findings of the present study demonstrate that hPDLSCs/rAd-BMP2 effectively promote osteogenesis not only in vitro but also in vivo. The findings also suggest that hPDLSCs can efficiently carry and deliver BMP2, and that hPDLSCs/rAd-BMP2 could be used in an attractive novel therapeutic approach for the regeneration of deteriorated bony defects.

Report of a newly indentified patient with mutations in BMP1 and underlying pathogenetic aspects

Osteogenesis imperfecta is a genetic condition characterized by bone fragility and recurrent fractures, which in the large majority of patients are caused by defects in the production of type I collagen. Mutations in the gene encoding bone morphogenetic protein 1 (BMP1, also known as procollagen C-endopeptidase) have been associated with osteogenesis imperfecta in two sib pairs. In this report, we describe an additional patient with osteogenesis imperfecta with normal bone density and a recurrent, homozygous c.34G>C mutation in BMP1. Western blot analysis of dermal fibroblasts from this patient showed decreased protein levels of the two alternatively spliced products of BMP1 and abnormal cleavage of the C-terminal propeptide of type I procollagen. In addition, fluorescence and electron microscopy showed impaired assembly of type I collagen fibrils in the extracellular matrix of cultured fibroblasts derived from two patients: the patient described here and a previously reported patient with a homozygous BMP1 c.747C>G mutation. We conclude that BMP1 is essential for human type I collagen fibrilogenesis.

S141 BMP9 is required for LPS-mediated neutrophil recruitment to PAH-patient derived blood outgrowth endothelial cells with BMPR-II mutations

IntroductionHeterozygous mutations in the gene encoding bone morphogenetic protein (BMP) receptor II (BMPR-II) are present in >70% of patients with heritable pulmonary arterial hypertension (hPAH) and 15–26% of idiopathic PAH...

Transcriptional repression of Bmp2 by p21Waf1/Cip1 links quiescence to neural stem cell maintenance

Relative quiescence and self renewal are defining features of adult stem cells, but their potential coordination remains unclear. Subependymal neural stem cells (NSCs) lacking cyclin-dependent kinase (CDK) inhibitor (CKI) 1a (p21) exhibit rapid expansion that is followed by their permanent loss later in life. Here we demonstrate that transcription of the gene encoding bone morphogenetic protein 2 (Bmp2) in NSCs is under the direct negative control of p21 through actions that are independent of CDK. Loss of p21 in NSCs results in increased levels of secreted BMP2, which induce premature terminal differentiation of multipotent NSCs into mature non-neurogenic astrocytes in an autocrine and/or paracrine manner. We also show that the cell-nonautonomous p21-null phenotype is modulated by the Noggin-rich environment of the subependymal niche. The dual function that we describe here provides a physiological example of combined cell-autonomous and cell-nonautonomous functions of p21 with implications in self renewal, linking the relative quiescence of adult stem cells to their longevity and potentiality.

A Case of Idiopathic Pulmonary Arterial Hypertension with aBMPR2Mutation

본 증례는 국내에서 처음으로 밝혀진 BMPR2 ìœ ì „ìž 돌연변이에 의한 폐동맥 ê³ í˜ˆì••ì¼ 뿐 아니라 ì „ ì„¸ê³„ì ìœ¼ë¡œë„ 처음 발견된 exon 8의 c.1042_1047delGTTATT 돌연변이에 대한 ë³´ê³ ì´ë‹¤. 환자는 NYHA class III ì •ë„ì˜ 운동 시 호흡곤란 및 객혈로 내원한 43세 남자 환자로서 특발성 íë™ë§¥ê³ í˜ˆì••ìœ¼ë¡œ 확진되었다. 중심 단어: íë™ë§¥ê³ í˜ˆì••; BMPR2 돌연변이

A new haplotype in BMP4 implicated in ossification of the posterior longitudinal ligament (OPLL) in a Chinese population

Previous genome-wide microarray analysis of candidate genes involved in the ossification of the posterior longitudinal ligament (OPLL) of the spine resulted in the identification of a novel, clinically relevant gene encoding bone morphogenetic protein 4 (BMP4) but was defined only by its expression patterns. The complete genomic BMP4 coding DNA from 450 patients with OPLL and 550 matched controls were sequenced and compared. We identified 18 SNPs, among which the minor alleles of SNP8 (C>T; p < 0.001; OR: 1.58), SNP13 (rs17563C>T; p < 0.001; OR: 1.76), and SNP14 (rs76335800A>T; p < 0.001; OR: 1.68) were associated with OPLL. Logistic regression analysis showed that the additive model of SNP8 (p < 0.001; OR: 3.48), SNP13 (p < 0.001; OR: 2.22), and SNP14 (p < 0.001; OR: 1.99) retained statistical significance. Linkage disequilibrium (LD) analysis identified a 3-kbp block of intense LD in BMP4 and 1 specific haplotype, TGGGCTT (p < 0.001, OR: 2.54), which was associated with OPLL-associated risk alleles and increased severity of OPLL, as shown by the distribution of ossified vertebrae in patients with OPLL (p = 0.002). Novel mutations in the BMP4 gene and a specific haplotype TGGGCTT appear to contribute to the risk of developing OPLL. Also the severity of OPLL seems to be mediated predominantly by genetic variations in this specific BMP4 gene region, but might be associated with other certain clinical and demographic characteristics in the Chinese population studied.

Pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: pathophysiology

Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are two of the key subgroups of pulmonary hypertension. They are characterised by different risk factors. PAH can be associated with mutations in the gene encoding bone morphogenetic protein receptor type II (BMPR2), HIV infection, congenital heart disease, connective tissue disease (such as systemic sclerosis), and exposure to particular drugs and toxins including fenfluramine derivatives. In contrast, CTEPH can be associated with anti-phospholipid antibodies, splenectomy and the presence of a ventriculo-atrial shunt or an infected pacemaker. The first-line therapies used to treat PAH and CTEPH also differ. While medical therapy tends to be used for patients with PAH, pulmonary endarterectomy is the treatment of choice for patients with CTEPH. However, there are possible common mechanisms behind the two diseases, including endothelial cell dysfunction and distal pulmonary artery remodelling. Further research into these similarities is needed to assist the development of targeted pharmacological therapies for patients with inoperable CTEPH and patients who have persistent pulmonary hypertension after endarterectomy.

Viral vector-induced expression of bone morphogenetic protein 2 produces inhibition of tumor growth and bone differentiation of stem cells

A number of hormonal factors have been shown to be instrumental in the calcification process. This study represents an attempt at using one of these factors to specifically induce calcification of tumors to arrest tumor growth. The gene encoding bone morphogenetic protein 2 (BMP-2) was placed under transcriptional control of the promoter for carcinoembryonic antigen (CEA). This gene cassette was cloned into a herpes simplex virus (HSV) amplicon vector (HSV-CEA-BMP2). This vector was used to induce local BMP-2 production in CEA-expressing tumor cells to retard cell growth. Lysates of tumor cells treated with HSV-CEA-BMP2 were applied to stem cells to determine if BMP-2 expression promotes differentiation to bone lineage. pHSV-CEA-BMP2 efficiently transduced both CEA-expressing and non-expressing cells. BMP-2 was only expressed in CEA-positive cells. BMP-2 expression led to an inhibition of tumor cell growth. BMP-2 released by these CEA-expressing tumors also drove the differentiation of mesenchymal stem cells to bone lineage. This proof-of-concept study demonstrates that tumor cells can be specifically engineered to produce BMP-2, which leads to growth retardation and to the differentiation of non-committed stem cells to bone. This 'Medusa' effect can theoretically be exploited to retard tumor growth.

Evidence of dysfunction of endothelial progenitors in pulmonary arterial hypertension.

Severe pulmonary arterial hypertension (PAH) is characterized by the formation of plexiform lesions and concentric intimal fibrosis in small pulmonary arteries. The origin of cells contributing to these vascular lesions is uncertain. Endogenous endothelial progenitor cells are potential contributors to this process. To determine whether progenitors are involved in the pathobiology of PAH. We performed immunohistochemistry to determine the expression of progenitor cell markers (CD133 and c-Kit) and the major homing signal pathway stromal cell-derived factor-1 and its chemokine receptor (CXCR4) in lung tissue from patients with idiopathic PAH, familial PAH, and PAH associated with congenital heart disease. Two separate flow cytometric methods were employed to determine peripheral blood circulating numbers of angiogenic progenitors. Late-outgrowth progenitor cells were expanded ex vivo from the peripheral blood of patients with mutations in the gene encoding bone morphogenetic protein receptor type II (BMPRII), and functional assays of migration, proliferation, and angiogenesis were undertaken. measurements and main results: There was a striking up-regulation of progenitor cell markers in remodeled arteries from all patients with PAH, specifically in plexiform lesions. These lesions also displayed increased stromal cell-derived factor-1 expression. Circulating angiogenic progenitor numbers in patients with PAH were increased compared with control subjects and functional studies of late-outgrowth progenitor cells from patients with PAH with BMPRII mutations revealed a hyperproliferative phenotype with impaired ability to form vascular networks. These findings provide evidence of the involvement of progenitor cells in the vascular remodeling associated with PAH. Dysfunction of circulating progenitors in PAH may contribute to this process.

Bone morphogenetic protein signalling in heritable versus idiopathic pulmonary hypertension

Mutations in the gene encoding bone morphogenetic protein (BMP) receptor type 2 (BMPR-2) have been reported in pulmonary arterial hypertension (PAH), but their functional relevance remains incompletely understood. BMP receptor expression was evaluated in human lungs and in cultured pulmonary artery smooth muscle cells (PASMCs) isolated from 19 idiopathic PAH patients and nine heritable PAH patients with demonstrated BMPR-2 mutations. BMP4-treated PASMCs were assessed for Smad and p38 mitogen-activated protein kinase (MAPK) signalling associated with mitosis and apoptosis. Lung tissue and PASMCs from heritable PAH patients presented with decreased BMPR-2 expression and variable increases in BMPR-1A and BMPR-1B expression, while a less important decreased BMPR-2 expression was observed in PASMCs from idiopathic PAH patients. Heritable PAH PASMCs showed no increased phosphorylation of Smad1/5/8 in the presence of BMP4, which actually activated the p38MAPK pathway. Individual responses varied from one mutation to another. PASMCs from PAH patients presented with an in vitro proliferative pattern, which could be inhibited by BMP4 in idiopathic PAH but not in heritable PAH. PASMCs from idiopathic PAH and more so from heritable PAH presented an inhibition of BMP4-induced apoptosis. Most heterogeneous BMPR-2 mutations are associated with defective Smad signalling compensated for by an activation of p38MAPK signalling, accounting for PASMC proliferation and deficient apoptosis.