RESUMO
Vascularization plays a significant role in promoting the expedited process of bone regeneration while also enhancing the stability and viability of artificial bone implants. Although titanium alloy scaffolds were designed to mimic the porous structure of human bone tissues to facilitate vascularization in bone repair, their biological inertness restricted their broader utilization. The unique attribute of Metal-organic framework (MOF) MIL-53(Fe), known as "breathing", can facilitate the efficient adsorption of extracellular matrix proteins and thus provide the possibility for efficient interaction between scaffolds and cell adhesion molecules, which helps improve the bioactivity of the titanium alloy scaffolds. In this study, MIL-53(Fe) was synthesized in situ on the scaffold after hydrothermal treatment. The MIL-53(Fe) endowed the scaffold with superior protein absorption ability and preferable biocompatibility. The scaffolds have been shown to possess favorable osteogenesis and angiogenesis inducibility. It was indicated that MIL-53(Fe) modulated the mechanotransduction process of endothelial cells and induced increased cell stiffness by promoting the adsorption of adhesion-mediating extracellular matrix proteins to the scaffold, such as laminin, fibronectin, and perlecan et al., which contributed to the activation of the endothelial tip cell phenotype at sprouting angiogenesis. Therefore, this study effectively leveraged the intrinsic "breathing" properties of MIL-53 (Fe) to enhance the interaction between titanium alloy scaffolds and vascular endothelial cells, thereby facilitating the vascularization inducibility of the scaffold, particularly during the sprouting angiogenesis phase. This study indicates that MIL-53(Fe) coating represents a promising strategy to facilitate accelerated and sufficient vascularization and uncovers the scaffold-vessel interaction from a biomechanical perspective.
Assuntos
Neovascularização Fisiológica , Alicerces Teciduais , Titânio , Titânio/química , Humanos , Alicerces Teciduais/química , Neovascularização Fisiológica/efeitos dos fármacos , Células Endoteliais/efeitos dos fármacos , Estruturas Metalorgânicas/química , Estruturas Metalorgânicas/farmacologia , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Osteogênese/efeitos dos fármacos , Ligas/química , Células Endoteliais da Veia Umbilical Humana , Próteses e Implantes , Mecanotransdução Celular , Adesão Celular/efeitos dos fármacos , Engenharia Tecidual/métodosRESUMO
The development of the neocortex involves an interplay between neural cells and the vasculature. However, little is known about this interplay at the ultrastructural level. To gain a 3D insight into the ultrastructure of the developing neocortex, we have analyzed the embryonic mouse neocortex by serial block-face scanning electron microscopy (SBF-SEM). In this study, we report a first set of findings that focus on the interaction of blood vessels, notably endothelial tip cells (ETCs), and the neural cells in this tissue. A key observation was that the processes of ETCs, located either in the ventricular zone (VZ) or subventricular zone (SVZ)/intermediate zone (IZ), can enter, traverse the cytoplasm, and even exit via deep plasma membrane invaginations of the host cells, including apical progenitors (APs), basal progenitors (BPs), and newborn neurons. More than half of the ETC processes were found to enter the neural cells. Striking examples of this ETC process "invasion" were (i) protrusions of apical progenitors or newborn basal progenitors into the ventricular lumen that contained an ETC process inside and (ii) ETC process-containing protrusions of neurons that penetrated other neurons. Our observations reveal a - so far unknown - complexity of the ETC-neural cell interaction.
RESUMO
Graphene oxide (GO) exhibits good mechanical and physicochemical characteristics and has extensive application prospects in bone tissue engineering. However, its effect on angiogenesis is unclear, and its potential toxic effects are heavily disputed. Herein, we found that nanographene oxide (NGO) synthesized by one-step water electrolytic oxidation is smaller and shows superior biocompatibility. Moreover, NGO significantly enhanced angiogenesis in calvarial bone defect areas in vivo, providing a good microenvironment for bone regeneration. Endothelial tip cell differentiation is an important step in the initiation of angiogenesis. We verified that NGO activates endothelial tip cells by coupling with lysophosphatidic acid (LPA) in serum via strong hydrogen bonding interactions, which has not been reported. In addition, the mechanism by which NGO promotes angiogenesis was systematically studied. NGO-coupled LPA activates LPAR6 and facilitates the formation of migratory tip cells via Hippo/Yes-associated protein (YAP) independent of reactive oxygen species (ROS) stimulation or additional complex modifications. These results provide an effective strategy for the application of electrochemically derived NGO and more insight into NGO-mediated angiogenesis.
RESUMO
During development, endothelial tip cells (ETCs) located at the leading edge of growing vascular plexus guide angiogenic sprouts to target vessels, and thus, ETC pathfinding is fundamental for vascular pattern formation in organs, including the brain. However, mechanisms of ETC pathfinding remain largely unknown. Here, we report that Piezo1-mediated Ca2+ activities at primary branches of ETCs regulate branch dynamics to accomplish ETC pathfinding during zebrafish brain vascular development. ETC branches display spontaneous local Ca2+ transients, and high- and low-frequency Ca2+ transients cause branch retraction through calpain and branch extension through nitric oxide synthase, respectively. These Ca2+ transients are mainly mediated by Ca2+-permeable Piezo1 channels, which can be activated by mechanical force, and mutating piezo1 largely impairs ETC pathfinding and brain vascular patterning. These findings reveal that Piezo1 and downstream Ca2+ signaling act as molecular bases for ETC pathfinding and highlight a novel function of Piezo1 and Ca2+ in vascular development.
Assuntos
Vasos Sanguíneos/crescimento & desenvolvimento , Encéfalo/irrigação sanguínea , Cálcio/metabolismo , Células Endoteliais/metabolismo , Canais Iônicos/genética , Neovascularização Fisiológica/genética , Proteínas de Peixe-Zebra/genética , Animais , Encéfalo/crescimento & desenvolvimento , Sinalização do Cálcio , Calpaína/metabolismo , Canais Iônicos/metabolismo , Mecanotransdução Celular , Mutação , Óxido Nítrico Sintase/metabolismo , Peixe-Zebra , Proteínas de Peixe-Zebra/metabolismoRESUMO
Angiogenesis is largely driven by motile endothelial tip-cells capable of invading avascular tissue domains and enabling new vessel formation. Highly responsive to Vascular Endothelial Growth-Factor-A (VEGFA), endothelial tip-cells also suppress angiogenic sprouting in adjacent stalk cells, and thus have been a primary therapeutic focus in addressing neovascular pathologies. Surprisingly, however, there remains a paucity of specific endothelial tip-cell markers. Here, we employ transcriptional profiling and a lacZ reporter allele to identify Kcne3 as an early and selective endothelial tip-cell marker in multiple angiogenic contexts. In development, Kcne3 expression initiates during early phases of angiogenesis (E9) and remains specific to endothelial tip-cells, often adjacent to regions expressing VEGFA. Consistently, Kcne3 activation is highly responsive to exogenous VEGFA but maintains tip-cell specificity throughout normal retinal angiogenesis. We also demonstrate endothelial tip-cell selectivity of Kcne3 in several injury and tumor models. Together, our data show that Kcne3 is a unique marker of sprouting angiogenic tip-cells and offers new opportunities for investigating and targeting this cell type.
Assuntos
Células Endoteliais/fisiologia , Neovascularização Patológica/genética , Neovascularização Fisiológica/genética , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Fator A de Crescimento do Endotélio Vascular/fisiologia , Animais , Animais Recém-Nascidos , Diferenciação Celular/genética , Células Cultivadas , Retinopatia Diabética/genética , Retinopatia Diabética/patologia , Embrião de Mamíferos , Células Endoteliais/patologia , Feminino , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Morfogênese/genética , Neovascularização Patológica/metabolismo , Gravidez , Retina/metabolismo , Retina/patologia , Vasos Retinianos/metabolismo , Vasos Retinianos/patologiaRESUMO
Exosomes secreted by adipose-derived stem cells (ADSCs) have been shown to promote angiogenesis. This study aimed to investigate the effect of exosomes from ADSCs (ADSCs-Exos) on proliferation and migration of endothelial tip cells. In this study, ADSCs were analyzed by flow cytometry. The protein levels were examined by western blot. Cell proliferation and migration were assessed by CCK-8 assay, EdU cell proliferation assay and transwell migration assay. A luciferase reporter assay was performed to confirm whether sema3A was a direct target of miR-199a/b-3p. The results showed that ADSCs-Exos strikingly promoted the proliferation and migration of endothelial tip cells. The expression levels of miR-199a-3p and miR-199b-3p were strikingly increased in ADSCs and ADSCs-Exos. Compared to the Exosscramble group, the proliferation and migration of endothelial tip cells was dramatically increased in the Exos199 mimic group, but remarkably decreased in the Exos199 inhibitor group. Moreover, Sema3A was a target of miR-199-3p. The stimulatory effects of Exos199 mimic on the proliferation and migration of endothelial tip cells were negated by Sema3A overexpression. Besides, the expression of tissue inhibitor of metalloproteinase 3 (TIMP3) was decreased, and the expression of matrix metalloproteinases 9 (MMP9) and proliferating cell nuclear antigen (PCNA) were increased in endothelial tip cells co-cultured with ADSCs-Exos, which were substantially enhanced by Exos199 mimic treatment. However, the effect of Exos199 mimic on the protein expression of TIMP3, MMP9 and PCNA were negated by upregulation of Sema3A. In conclusion, exosomes from miR-199-3p-modified ADSCs promote proliferation and migration of endothelial tip cells by downregulation of sema3A.
RESUMO
Filopodia are highly dynamic, rod-like protrusions that are found in abundance at the leading edge of migrating cells such as endothelial tip cells and at axonal growth cones of developing neurons. One proposed function of filopodia is that of an environmental probe, which serves to sense guidance cues during neuronal pathfinding and blood vessel patterning. However, recent studies show that tissue guidance occurs unhindered in the absence of filopodia, suggesting a dispensability of filopodia in this process. Here, we discuss evidence that support as well as dispute the role of filopodia in guiding the formation of stereotypic neuronal and blood vessel patterns.