Pathologic and enzyme histochemical studies on bone formation induced by bone morphogenetic protein in mouse muscle tissue

Tracheobronchopathia Osteochondroplastica Associated with Fibrotic Interstitial Lung Disease

Tracheobronchopathia osteochondroplastica (TPO) is a very rare, benign disorder involving the lumen of the trachea-bronchial tree. However, its etiology is unknown. In our first case, observation for several years showed that TPO worsened as interstitial lung disease was aggravated. In the second case, the lung parenchymal lesion on computed tomography (CT) was found to be compatible with interstitial lung abnormality (ILA). We believe that our cases suggest a common pathogenetic relationship between TPO and fibrotic interstitial lung disease. TGF-β is likely a common factor in the pathogenesis of TPO and fibrotic interstitial lung disease.

Biosilica: Molecular Biology, Biochemistry and Function in Demosponges as well as its Applied Aspects for Tissue Engineering

Biomineralization, biosilicification in particular (i.e. the formation of biogenic silica, SiO(2)), has become an exciting source of inspiration for the development of novel bionic approaches following 'nature as model'. Siliceous sponges are unique among silica-forming organisms in their ability to catalyze silica formation using a specific enzyme termed silicatein. In this study, we review the present state of knowledge on silicatein-mediated 'biosilica' formation in marine demosponges, the involvement of further molecules in silica metabolism and their potential applications in nano-biotechnology and bio-medicine. While most forms of multicellular life have developed a calcium-based skeleton, a few specialized organisms complement their body plan with silica. Only sponges (phylum Porifera) are able to polymerize silica enzymatically mediated in order to generate massive siliceous skeletal elements (spicules) during a unique reaction, at ambient temperature and pressure. During this biomineralization process (i.e. biosilicification), hydrated, amorphous silica is deposited within highly specialized sponge cells, ultimately resulting in structures that range in size from micrometres to metres. This peculiar phenomenon has been comprehensively studied in recent years, and in several approaches, the molecular background was explored to create tools that might be employed for novel bioinspired biotechnological and biomedical applications. Thus, it was discovered that spiculogenesis is mediated by the enzyme silicatein and starts intracellularly. The resulting silica nanoparticles fuse and subsequently form concentric lamellar layers around a central protein filament, consisting of silicatein and the scaffold protein silintaphin-1. Once the growing spicule is extruded into the extracellular space, it obtains final size and shape. Again, this process is mediated by silicatein and silintaphin-1/silintaphin-1, in combination with other molecules such as galectin and collagen. The molecular toolbox generated so far allows the fabrication of novel micro- and nano-structured composites, contributing to the economical and sustainable synthesis of biomaterials with unique characteristics. In this context, first bioinspired approaches implement recombinant silicatein and silintaphin-1 for applications in the field of biomedicine (biosilica-mediated regeneration of tooth and bone defects) with promising results.

BMPs: Options, indications, and effectiveness

Alteration of the bone healing process with bone morphogenetic proteins offers a new perspective in orthopaedic surgery in those adverse situations that necessitate bone grafting. BMPs have been demonstrated to be effective and safe for human application and have an efficacy comparable with that of autologous bone grafting. Nevertheless, clinical trials with level 1 evidence are still limited in their ability to extrapolate robust and safe clinical conclusions for the possible indications mentioned in this article. Future research should refine issues regarding the relative effectiveness of bone morphogenetic proteins, the interaction between bone morphogenetic protein subtypes, and their specific effect on various target cell populations.

Molecular mechanisms of HIF-1alpha modulation induced by oxygen tension and BMP2 in glioblastoma derived cells

Background

Glioblastoma multiforme (GBM) is one of most common and still poorly treated primary brain tumors. In search for new therapeutic approaches, Bone Morphogenetic Proteins (BMPs) induce astroglial commitment in GBM-derived cells in vitro. However, we recently suggested that hypoxia, which is characteristic of the brain niche where GBM reside, strongly counter-acts BMP effects. It seems apparent that a more complete understanding of the biology of GBM cells is needed, in particular considering the role played by hypoxia as a signaling pathways regulator. HIF-1α is controlled at the transcriptional and translational level by mTOR and, alike BMP, also mTOR pathway modulates glial differentiation in central nervous system (CNS) stem cells.

Methodology/Principal Findings

Here, we investigate the role of mTOR signaling in the regulation of HIF-1α stability in primary GBM-derived cells maintained under hypoxia (2% oxygen). We found that GBM cells, when acutely exposed to high oxygen tension, undergo Akt/mTOR pathway activation and that BMP2 acts in an analogous way. Importantly, repression of Akt/mTOR signaling is maintained by HIF-1α through REDD1 upregulation. On the other hand, BMP2 counter-acts HIF-1α stability by modulating intracellular succinate and by controlling proline hydroxylase 2 (PHD2) protein through inhibition of FKBP38, a PHD2 protein regulator.

Conclusions/Significance

In this study we elucidate the molecular mechanisms by which two pro-differentiating stimuli, BMP2 and acute high oxygen exposure, control HIF-1α stability. We previously reported that both these stimuli, by inducing astroglial differentiation, affect GBM cells growth. We also found differences in high oxygen and BMP2 sensitivity between GBM cells and normal cells that should be further investigated to better define tumor cell biology.

Intramuscular osteoinduction and bone marrow formation by the implantation of rhBMP-2 with atelopeptide type I collagen

The study examines the osteoinductive potential of recombinant human morphogenetic protein 2 (rhBMP-2) radiologically and histologically in rat calf muscle. Ten male Wistar rats were used. rhBMP-2 50 microg was implanted with atelopeptide type I collagen as carrier in a pouch in rat calf muscle (n = 5), and atelopeptide type I collagen alone was implanted in a further five as control. Induction of osteogenesis at 4 weeks was investigated. In all rats in which rhBMP-2 had been implanted there was a radio-opaque shadow in the muscle in the soft tissue radiograph. No such shadows were noted in the control group. Histological examination showed bony trabeculum, osteoblasts, and vigorous bone marrow including fatty marrow and angioid tissue both at the margins and in the center of the excised lumps in the rhBMP-2 group. There were no such signs in the control group. rhBMP-2 may be capable not only of inducing the formation of bone, but also of inducing a 'self-supporting bone organ' in the muscle.

Immunohistochemical evaluation of bone morphogenetic protein (BMP) in mixed tumor of skin

Immunohistochemical reaction of bone morphogenetic protein (BMP) was assessed in 19 cases of skin mixed tumor and 5 cases of skin appendage tumors by using monoclonal antibody raised against BMP. All cases of skin mixed tumor showed positive staining for BMP in modified myoepithelial cells located at the periphery of tubulo-ductal or solid structures, and in plasmacytoid or tumor cells in hyalinous structures. Chondroidally changed cells also showed a strong BMP immunoreactivity. Tumors originating from sweat glands were devoid of BMP immunoreactivity. It is concluded that BMP is synthesized and produced in modified or transformed myoepithelial cells in skin mixed tumor and participates in the process of chondroid changes in the tumor.

Histogenesis and possible mechanism of chondroid changes in mixed tumour of the skin: immunohistochemical evaluation of bone morphogenetic protein, glycosaminoglycans, keratin, vimentin and neuronal markers

The distribution of immunoreactivity of bone morphogenetic protein (BMP), the glycosaminoglycans chondroitin 4-sulphate (C4SPG), chondroitin 6-sulphate (C6SPG), dermatan sulphate (DSPG) and keratan sulphate proteoglycans (KSPG), cytokeratin (K8.12), vimentin, glial fibrillary acidic protein (GFAP), actin, desmin, S-100 protein and neuron-specific enolase (NSE) in mixed tumour of the skin was investigated using immunohistochemical methods using monoclonal (MoAb) and polyclonal antibodies (PoAb). A strong BMP immunoreactivity was found characteristically in outer tumour cells of tubuloductal structures and modified myoepithelial cells. Modified myoepithelial cells and chondroidally changed cells showed positive immunoreactivity for C4SPG, C6SPG and DSPG; and KSPG was more pronounced in the modified myoepithelial cells. Vimentin, S-100 protein, GFAP and NSE, but not actin and desmin, were distribute in the outer tumour cells and modified myoepithelial cells in chondroidally changed tissue. Two factors show that chondrogenesis in mixed tumour of the skin is associated with the modified myoepithelial cells through the activity of BMP and biosynthesis of glycosaminoglycans as matrix substance. First, outer or basal tumour cells in mixed tumour of the skin is characterized by the presence of positive immunoreactivity for BMP, KSPG, vimentin, cytokeratin K8.12, S-100 protein, GFAP and NSE, and second, there is a matrix of chondroidally changed tissue containing the reaction products of C4SPG, C6SPG, DSPF and KSPG.

An immunohistochemical study of bone morphogenetic protein in pleomorphic adenoma of the salivary gland

Bone morphogenetic protein (BMP) is a potent induction factor for new bone formation including heterotopic chondro-ossification in soft tissues. The immunohistochemical reaction for BMP was studied in 23 cases of pleomorphic adenoma of salivary gland by using a monoclonal antibody produced by hybridoma technique. Positive BMP immunoreactivity was seen in 87% of tumours. Immunohistochemical expression of BMP was observed in modified myoepithelial cells (88% cases), luminal tumour cells of tubulo-ductal structures (78% cases) and chondroid cells in hyaline tissue (22% cases). The authors concluded that the simultaneous presence of glycosaminoglycans as matrix substance with BMP-mediated cellular activity of modified myoepithelial cells in the formation of chondroid structures in pleomorphic adenomas of the salivary glands.

Immunohistochemical localization of bone morphogenetic protein (BMP) in calcifying fibrous epulis

Immunohistochemical detection of bone morphogenetic protein (BMP) in calcifying fibrous epulis was performed to elucidate the biological process of ossification and cemento-ossification. In a total 25 cases, 15 (60%) showed positive BMP staining in bone forming areas. Histopathological features of developing hard tissues were varied, consisting of structures such as woven bone and cemento-osseous formations. BMP immunostaining was limited to osteoblasts and fibrous connective tissue surrounding the bone matrix. BMP was concentrated in the periodontal fibres and in dense fibrous structures in the cemento-osseous masses. On the basis of histopathological and immunohistochemical features, the histogenesis of ossifying and cemento-ossifying processes appear to be of two possible origins; the excessive proliferation of periodontal ligament and a metaplastic process occurring in the connective tissue fibres (non-periodontal in origin), with the former being more common.