Interactions of Human Endothelial and Multipotent Mesenchymal Stem Cells in Cocultures

Current strategies for tissue engineering of bone rely on the implantation of scaffolds, colonized with human mesenchymal stem cells (hMSC), into a recipient. A major limitation is the lack of blood vessels. One approach to enhance the scaffold vascularisation is to supply the scaffolds with endothelial cells (EC)

GDF-15 is abundantly expressed in plexiform lesions in patients with pulmonary arterial hypertension and affects proliferation and apoptosis of pulmonary endothelial cells

<p>Abstract</p> <p>Background</p> <p>Growth-differentiation factor-15 (GDF-15) is a stress-responsive, transforming growth factor-β-related cytokine, which has recently been reported to be elevated in serum of patients with idiopathic pulmonary arterial hypertension (IPAH). The aim of the study was to examine the expression and biological roles of GDF-15 in the lung of patients with pulmonary arterial hypertension (PAH).</p> <p>Methods</p> <p>GDF-15 expression in normal lungs and lung specimens of PAH patients were studied by real-time RT-PCR and immunohistochemistry. Using laser-assisted micro-dissection, GDF-15 expression was further analyzed within vascular compartments of PAH lungs. To elucidate the role of GDF-15 on endothelial cells, human pulmonary microvascular endothelial cells (HPMEC) were exposed to hypoxia and laminar shear stress. The effects of GDF-15 on the proliferation and cell death of HPMEC were studied using recombinant GDF-15 protein.</p> <p>Results</p> <p>GDF-15 expression was found to be increased in lung specimens from PAH patients, com-pared to normal lungs. GDF-15 was abundantly expressed in pulmonary vascular endothelial cells with a strong signal in the core of plexiform lesions. HPMEC responded with marked upregulation of GDF-15 to hypoxia and laminar shear stress. Apoptotic cell death of HPMEC was diminished, whereas HPMEC proliferation was either increased or decreased depending of the concentration of recombinant GDF-15 protein.</p> <p>Conclusions</p> <p>GDF-15 expression is increased in PAH lungs and appears predominantly located in vascular endothelial cells. The expression pattern as well as the observed effects on proliferation and apoptosis of pulmonary endothelial cells suggest a role of GDF-15 in the homeostasis of endothelial cells in PAH patients.</p

Das murine Leuk&auml;mievirus Akv wirkt als Promoter der Knochentumorentwicklung fos-transgener M&auml;use.

Newborn hMT-fos-LTR transgenic C3H mice and their non-transgenic siblings were infected with Akv, derived from the ecotropic provirus of the AKR mouse. Bone sarcomas in non-infected transgenics were observed in 20% (3/15) of females at 448 +/- 25 days and in 8% (1/12) of males at 523 days. Akv-infected transgenics developed bone tumors with higher frequency and at younger age: Females in 69% (20/28) at 268 +/- 122 days, males in 83% (24/29) at 279 +/- 109 days. In the majority of the bone tumors of Akv-infected transgenics (70% in females, 59% in males) cellular atypia was lacking and the histological pattern resembled human parosteal osteosarcoma. Only 50% (12/24) of bone tumors in Akv-infected transgenics revealed newly integrated virus sequences by Southern analysis. PCR analysis detected Akv sequences in DNAs of all tumors. Obviously, the insertion of Akv in a few cells induced the considerably accelerated bone tumor growth

Vascular Targeted Agents for the Treatment of Angiosarcoma

Background: Angiogenesis is the process of new blood vessel formation, and is regulated by angiogenic growth factors including vascular endothelial growth factor (VEGF). Angiosarcomas are rare, aggressive vascular tumours. Studies were performed to investigate the expression of angiogenic growth factors in angiosarcoma, and to assess vascular targeted agents for the treatment of angiosarcoma. Methods: In vitro studies compared two human cutaneous angiosarcoma cell lines (ASM and ISO-HAS) with human dermal microvascular endothelial cells (HuDMECs). The cell lines were compared in functional assays, including cell viability, cell differentiaiton and cell migration assays, and protein expression profiled using antibody arrays. Cell responses to vascular targeted agents were compared, including response to bevacizumab an anti-VEGF antibody, axitinib a VEGF receptor (VEGFR) tyrosine kinase inhibitor, selumetinib a MEK inhibitor, and DMXAA a vascular disrupting agent. Immunohistochemistry studies measured the expression of angiogenic growth factors in angiosarcoma tumour specimens using benign vascular lesions for comparison, and assessed canine angiosarcoma as a model of human angiosarcoma. Results: ASM and ISO-HAS demonstrated accelerated growth kinetics, chaotic tubule formation, and increased cell migration compared to HuDMECs. ASM and ISO-HAS expressed significantly increased VEGF compared to HuDMECs. Only minor responses were observed to VEGF targeted agents in functional assays despite western blot studies that showed target inhibition of VEGFR2 phosphorylation,. Striking responses were seen however to selumetinib and DMXAA. Immunohistochemistry studies demonstrated benign and malignant vascular tumours expressed a range of pro-angiogenic growth factors, however analysis did not distinguish malignant from benign vascular tumours. The morphology of canine angiosarcoma was similar to human angiosarcoma. VEGF and VEGFR2 expression was significantly increased in canine angiosarcoma compared to benign vascular lesions. Conclusion: These studies predict limited in vivo angiosarcoma tumour response to VEGF targeted agents. Selumetinib and DMXAA are suggested for further study. Canine angiosarcomas represent a potential model of human angiosarcoma to be explored in future studies