Project description:Endochondral ossification (EO) is the natural route for the regeneration of large and mechanically challenged bone defects. Regeneration occurs via a fibrocartilagenous phase which turns into bone upon vascularization and the formation of a transient collagen type X extra cellular matrix. These two critical initiator of EO are mediated by Hedgehog proteins. We investigated a tissue engineering approach using Sonic Hedgehog (Shh) as a pleiotropic factor regulating the in vitro formation of a vascularized bone tissue precursor for in vivo endochondral bone formation. The tissue engineered graft was formed using human mesenchymal stem cells and prevascularized using human umbilical vein endothelial cells. We show that Shh induced, in vitro, the maturation of the engineered vascular network along with the expression of collagen type X which resulted, in vivo, in an improved vascularization and the rapid formation of large amounts of osteoids through EO. Osteoids further matured into, currently unmatched, clinically relevant amount of lamellar bone including osteoclasts, bone lining cells and bone marrow-like cavities. This result suggests that Hh is a master regulator of EO allowing for the formation of complex tissues with considerable therapeutic potential for bone regeneration. The effect of Cyclopamine on expression of Hedgehog, angiogenesis and axon guidance marker genes was analyzed by seeding a coculture of 92% hMSCs and 8% huvEC supplemented or not in cyclopamine, for 12 days
Project description:Endochondral ossification (EO) is the natural route for the regeneration of large and mechanically challenged bone defects. Regeneration occurs via a fibrocartilagenous phase which turns into bone upon vascularization and the formation of a transient collagen type X extra cellular matrix. These two critical initiator of EO are mediated by Hedgehog proteins. We investigated a tissue engineering approach using Sonic Hedgehog (Shh) as a pleiotropic factor regulating the in vitro formation of a vascularized bone tissue precursor for in vivo endochondral bone formation. The tissue engineered graft was formed using human mesenchymal stem cells and prevascularized using human umbilical vein endothelial cells. We show that Shh induced, in vitro, the maturation of the engineered vascular network along with the expression of collagen type X which resulted, in vivo, in an improved vascularization and the rapid formation of large amounts of osteoids through EO. Osteoids further matured into, currently unmatched, clinically relevant amount of lamellar bone including osteoclasts, bone lining cells and bone marrow-like cavities. This result suggests that Hh is a master regulator of EO allowing for the formation of complex tissues with considerable therapeutic potential for bone regeneration.
Project description:Successful implantation and long-term survival of engineered tissue grafts hinges on adequate vascularization of the implant. Endothelial cells are essential for patterning vascular structures, but they require supportive mural cells such as pericytes/mesenchymal stem cells (MSCs) to generate stable, functional blood vessels.1-5 While there is evidence that the angiogenic effect of MSCs is mediated via the secretion of paracrine signals,6,7 the identity of these signals is unknown. Here, by utilizing two functionally distinct human MSC clones, we found that so-called “pericytic” MSCs secrete the pro-angiogenic neurovascular guidance molecule SLIT3,8 which guides vascular development by directing ROBO4-positive endothelial cells to form networks in engineered tissue. In contrast, “non-pericytic” MSCs exhibit reduced activation of the SLIT3/ROBO4 pathway and do not support vascular networks. Using live cell imaging of organizing 3D vascular networks, we show that knockdown of SLIT3 in MSCs leads to disorganized clustering of ECs, and knockdown of its receptor ROBO4 in ECs abolishes the generation of functional human blood vessels in an in vivo xenogenic implant. These data suggest that the SLIT3/ROBO4 pathway regulates MSC-guided vascularization in engineered tissues. Heterogeneity of SLIT3 expression may underlie the variable clinical success of MSCs for tissue repair applications. 4 samples with 2 replicates each
Project description:Formation of organ-specific vasculatures requires cross-talk between developing tissue and specialized endothelial cells. Here we show how developing zebrafish spinal cord neurons coordinate vessel growth through balancing of neuron-derived Vegfaa, with neuronal sFlt1 restricting Vegfaa-Kdrl mediated angiogenesis at the neurovascular interface. Neuron-specific loss of flt1 or increased neuronal vegfaa expression promotes angiogenesis and peri-neural tube vascular network formation. Combining loss of neuronal flt1 with gain of vegfaa promotes sprout invasion into the neural tube. Upon loss of neuronal flt1, ectopic sprouts emanate from veins involving special angiogenic cell behaviors including nuclear positioning and a molecular signature distinct from primary artery or secondary venous sprouting. Manipulation of AV identity or Notch signaling established that ectopic sprouting in flt1 mutants requires venous endothelium. Conceptually our data suggest that spinal cord vascularization proceeds from veins involving two-tiered regulation of neuronal sFlt1 and Vegfaa via a novel sprouting mode.
Project description:In order to find the difference between human lung tissue-derived fibroblasts and human vascular adventitial fibroblasts for enhancing tumor formation ablity of human lung adenocarcinoma cell line A549, we found that human vascular adventitial fibroblasts enhance A549 tumor formation in vivo compared to human lung tissue-derived fibroblasts. To find the responsible genes for this phenomena, we used microarray analysis to find the expression difference between lung tissue-derived fibroblasts and vascular adventitial fibroblas Cultured human lung tissue-derived fibroblasts and human vascular adventitial fibroblasts were analyzed in replicates.
Project description:In order to find the difference between human lung tissue-derived fibroblasts and human vascular adventitial fibroblasts for enhancing tumor formation ablity of human lung adenocarcinoma cell line A549, we found that human vascular adventitial fibroblasts enhance A549 tumor formation in vivo compared to human lung tissue-derived fibroblasts. To find the responsible genes for this phenomena, we used microarray analysis to find the expression difference between lung tissue-derived fibroblasts and vascular adventitial fibroblas
Project description:Formation of blood vessels requires the concerted regulation of an unknown number of genes in a spatial-, time- and dosage-dependent manner. We investigated vascular development in vivo by determining global gene regulation throughout the formation of the chick chorio-allantoic membrane (CAM). Our study provides a comprehensive molecular map of vascular maturation during developmental angiogenesis and might thus be a valuable resource to streamline further research of candidates susceptible to mediate pathological angiogenesis.
Project description:Numerous studies have suggested a link between fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) signaling pathways; however the nature of this link has not been established. To evaluate this relationship we investigated VEGF signaling in endothelial cells with disrupted FGF signaling in vitro and in vivo. We find that endothelial cells lacking FGF signaling become unresponsive to VEGF due to down regulation of VEGFR2 expression caused by reduced Vegfr2 enhancer activation, which is in turn caused by reduced activation of Ets family transcription factors. In vivo this manifests in the loss of vascular integrity and morphogenesis. Thus, basal FGF stimulation of the endothelium is required for maintenance of VEGFR2 expression and the ability to respond to VEGF stimulation and accounts for the hierarchic control of vascular formation by FGFs and VEGF. Primary mouse lung endothelial cells were transduced with either Adeno-Null (empty) or Adeno- dominant negative FGF receptor 1 and harvested 24 hours after transduction. Total RNA was extracted and subjected to the analysis using SuperArray GEArray Q Series Mouse Angiogenesis Gene Array. Comparisons were made between treatments.
Project description:Here we report the reprogramming of human fibroblasts to produce chemically-induced osteogenic cells (ciOG), and explore the potential uses of ciOG in bone repair and disease treatment. A chemical cocktail of RepSox, forskolin, and phenamil was used for osteogenic induction of fibroblasts by activation of RUNX2 expression. Following a maturation, the cells differentiated toward an osteoblast phenotype that produced mineralized tissue. When generated on a nanofiber substrate ciOG accelerated osteogenic gene expressions and mineralization compared to PCL film followed by bone matrix formation in a calvarial defect, indicating that the engineered biomaterial promotes the osteogenic capacity of ciOG in vivo.
Project description:Successful implantation and long-term survival of engineered tissue grafts hinges on adequate vascularization of the implant. Endothelial cells are essential for patterning vascular structures, but they require supportive mural cells such as pericytes/mesenchymal stem cells (MSCs) to generate stable, functional blood vessels.1-5 While there is evidence that the angiogenic effect of MSCs is mediated via the secretion of paracrine signals,6,7 the identity of these signals is unknown. Here, by utilizing two functionally distinct human MSC clones, we found that so-called “pericytic” MSCs secrete the pro-angiogenic neurovascular guidance molecule SLIT3,8 which guides vascular development by directing ROBO4-positive endothelial cells to form networks in engineered tissue. In contrast, “non-pericytic” MSCs exhibit reduced activation of the SLIT3/ROBO4 pathway and do not support vascular networks. Using live cell imaging of organizing 3D vascular networks, we show that knockdown of SLIT3 in MSCs leads to disorganized clustering of ECs, and knockdown of its receptor ROBO4 in ECs abolishes the generation of functional human blood vessels in an in vivo xenogenic implant. These data suggest that the SLIT3/ROBO4 pathway regulates MSC-guided vascularization in engineered tissues. Heterogeneity of SLIT3 expression may underlie the variable clinical success of MSCs for tissue repair applications.