A Fully Human Monoclonal Antibody Targeting cKIT Is a Potent Inhibitor of Pathological Choroidal Neovascularization in Mice.

Stem cell factor (SCF) and its receptor, cKIT, are novel regulators of pathological neovascularization in the eye, which suggests that inhibition of SCF/cKIT signaling may be a novel pharmacological strategy for treating neovascular age-related macular degeneration (AMD). This study evaluated the therapeutic potential of a newly developed fully human monoclonal antibody targeting cKIT, NN2101, in a murine model of neovascular AMD. In hypoxic human endothelial cells, NN2101 substantially inhibited the SCF-induced increase in angiogenesis and activation of the cKIT signaling pathway.

Src tyrosine kinase regulates the stem cell factor-induced breakdown of the blood-retinal barrier.

Purpose: Stem cell factor (SCF) has been recently acknowledged as a novel endothelial permeability factor. However, the mechanisms by which SCF-induced activation of the SCF cognate receptor, cKit, enhances endothelial permeability have not been fully elucidated. This study aimed to investigate the role of Src in SCF-induced breakdown of the blood-retinal barrier (BRB).

Fibroblast Growth Factor 12 Is a Novel Regulator of Vascular Smooth Muscle Cell Plasticity and Fate.

Objective: Vascular smooth muscle cells (VSMCs) modulate their phenotype between synthetic and contractile states in response to environmental changes; this modulation plays a crucial role in the pathogenesis of restenosis and atherosclerosis. Here, we identified fibroblast growth factor 12 (FGF12) as a novel key regulator of the VSMC phenotype switch.

Approach And Results: Using murine models and human specimens, we found that FGF12 was highly expressed in contractile VSMCs of normal vessel walls but was downregulated in synthetic VSMCs from injured and atherosclerotic vessels.

Stem cell factor is a potent endothelial permeability factor.

Objective: Although stem cell factor (SCF) has been shown to play a critical role in hematopoiesis, gametogenesis, and melanogenesis, the function of SCF in the regulation of vascular integrity has not been studied.

Approach And Results: We demonstrated that SCF binds to and activates the cKit receptor in endothelial cells, thereby increasing the internalization of vascular endothelial-cadherin and enhancing extravasation of dyes to a similar extent as vascular endothelial growth factor. SCF-mediated cKit activation in endothelial cells enhanced the phosphorylation of endothelial nitric oxide (NO) synthase via the phosphoinositide 3-kinase/Akt signaling pathway and subsequently increased the production of NO.

Reactive oxygen species regulate the quiescence of CD34-positive cells derived from human embryonic stem cells.

Aims: Reactive oxygen species (ROS) are involved in a wide range of cellular processes. However, few studies have examined the generation and function of ROS in human embryonic vascular development. In this study, the sources of ROS and their roles in the vascular differentiation of human embryonic stem cells (hESCs) were investigated.

Cooperation of endothelial and smooth muscle cells derived from human induced pluripotent stem cells enhances neovascularization in dermal wounds.

Human induced pluripotent stem cells (hiPSCs) are generated through the reprogramming of somatic cells into an embryonic stem cell-like state, such that vascular cells differentiated from hiPSCs might be a suitable autologous cell source for vascular regeneration. The goal of this study was to assess whether cotransplantation of endothelial cells (ECs) and smooth muscle cells (SMCs) differentiated from hiPSCs could promote neovascularization and tissue repair in a murine dermal wound model. hiPSCs were differentiated into ECs and SMCs; the differentiated cells displayed cell-specific surface markers.

Distinct transcriptional profiles of angioblasts derived from human embryonic stem cells.

Identification of differentially expressed genes in angioblasts derived from human embryonic stem cells (hESCs) is of great interest for elucidating the molecular mechanisms underlying human vasculogenesis. The aim of this study was to define hESC-derived angioblasts at the clonal level and to perform comparative transcriptional analysis to characterize their distinct gene expression profiles. In a clonal analysis performed in cell-specific differentiation media, hESC-derived CD34(+)CD31(+) cells were identified as angioblasts in that they exhibited a significantly higher ability to form endothelial cell (EC) and smooth muscle cell (SMC) colonies than CD34(+)CD31(-) and CD34(-) cell populations did.

Positive correlation between the dysregulation of transforming growth factor-β1 and aneurysmal pathological changes in patients with Marfan syndrome.

Background: Our goal was to investigate the correlation between the dysregulation of transforming growth factor-β1 (TGF-β1) and cystic medial degeneration in the aortic aneurysmal tissues of in Marfan syndrome (MFS) patients. Although aortic aneurysm in animal models of MFS is related to the dysregulation of TGF-β, it has yet to be determined whether TGF-β dysregulation correlates with pathogenic aneurysmal characteristics in MFS patients.

Methods And Results: Compared with aortic tissue from normal individuals, the medial layers of aortic tissue from MFS patients exhibited profound cystic medial degeneration and cellular apoptosis.

alpha B-crystallin is expressed in myelinating oligodendrocytes of the developing and adult avian retina.

It is well known that the expression of α B-crystallin (aBC) is increased in neurons and glia under pathologic conditions. However, the expression of aBC during the normal development of the central nervous system has not been reported. This study aimed to clarify the cell type in the chick retina in which aBC is expressed and timing of aBC expression in this cell type during development.

Tie1 regulates the Tie2 agonistic role of angiopoietin-2 in human lymphatic endothelial cells.

Although Angiopoietin (Ang) 2 has been shown to function as a Tie2 antagonist in vascular endothelial cells, several recent studies on Ang2-deficient mice have reported that, like Ang1, Ang2 acts as a Tie2 agonist during in vivo lymphangiogenesis. However, the mechanism governing the Tie2 agonistic activity of Ang2 in lymphatic endothelial cells has not been investigated. We found that both Ang1 and Ang2 enhanced the in vitro angiogenic and anti-apoptotic activities of human lymphatic endothelial cells (HLECs) through the Tie2/Akt signaling pathway, while only Ang1 elicited such effects in human umbilical vein vascular endothelial cells (HUVECs).

Vascular differentiation of multipotent spermatogonial stem cells derived from neonatal mouse testis.

We previously reported the successful establishment of embryonic stem cell (ESC)-like multipotent spermatogonial stem cells (mSSCs) from neonatal mouse testis. Here, we examined the ability of mSSCs to differentiate into vascular endothelial cells and smooth muscle cells, and compared to that of mouse ESCs. We used real-time reverse transcriptase polymerase chain reaction and immunohistochemistry to examine gene expression profiles of mSSCs and ESCs during in vitro vascular differentiation.

Angiopoietin-1 gene therapy attenuates hypertension and target organ damage in nitric oxide synthase inhibited spontaneously hypertensive rats.

Background And Objectives: In our previous study, we found that the gene transfer of a potent derivative of cartilage oligomeric matrix protein Angiopoietin-1 (COMP-Ang-1) substantially prevented hypertension, microvascular rarefaction, and target organ damage in spontaneously hypertensive rats (SHRs). The purpose of the present study was to examine the role of nitric oxide (NO) in the therapeutic effects observed after COMP-Ang-1 gene transfer.

Materials And Methods: To exclude the NO-mediated effects in COMP-Ang-1 gene therapy, the SHRs were treated with an NO synthase (NOS) inhibitor, N(w)-nitro-L-arginine methyl ester (L-NAME) before the electrophoretic gene transfer.

Human cord blood-derived endothelial progenitor cells and their conditioned media exhibit therapeutic equivalence for diabetic wound healing.

Transplantation of human cord blood-derived endothelial progenitor cells (EPCs) is reported to contribute to neovascularization in various ischemic diseases. However, the possible beneficial role and underlying mechanisms in diabetes-impaired wound healing have been less well characterized. In this study, EPC transplantation stimulated keratinocyte and fibroblast proliferation substantially as early as 3 days after injury, leading to significantly accelerated wound closure in streptozotocin-induced diabetic nude mice, compared to PBS control.

Functional recapitulation of smooth muscle cells via induced pluripotent stem cells from human aortic smooth muscle cells.

Rationale: Generation of induced pluripotent stem (iPS) cells has been intensively studied by a variety of reprogramming methods, but the molecular and functional properties of the cells differentiated from iPS cells have not been well characterized.

Objective: To address this issue, we generated iPS cells from human aortic vascular smooth muscle cells (HASMCs) using lentiviral transduction of defined transcription factors and differentiated these iPS cells back into smooth muscle cells (SMCs).

Methods And Results: Established iPS cells were shown to possess properties equivalent to human embryonic stem cells, in terms of the cell surface markers, global mRNA and microRNA expression patterns, epigenetic status of OCT4, REX1, and NANOG promoters, and in vitro/in vivo pluripotency.

Enhanced dermal wound neovascularization by targeted delivery of endothelial progenitor cells using an RGD-g-PLLA scaffold.

Endothelial progenitor cells (EPCs), endothelial precursors that promote neovascularization in ischemic tissues, have shown the limited vascular regeneration efficacy due to their poor homing into injured sites and low survival, so that a variety of biosynthetic scaffolds have been employed as cell delivery vehicles to overcome the current cell transplantation methods. However, few paralleled studies that directly compare the efficacy of EPCs seeded within synthetic scaffolds to that of EPCs delivered by the conventional transplantation techniques used for EPC therapies have been performed. To address these issues, RGD-g-PLLA biosynthetic scaffold was developed for the targeted EPC delivery and was found to successfully support the in vitro growth and endothelial functions of EPCs.

Angiopoietin-1 prevents hypertension and target organ damage through its interaction with endothelial Tie2 receptor.

Aims: The endothelium has emerged recently as a therapeutic target in the treatment of hypertension because endothelial dysfunction and subsequent vascular rarefaction cause target organ damage and further elevate blood pressure (BP). It led us to hypothesize that one of the endothelial survival factors, a potent derivative of angiopoietin-1 (cartilage oligomeric matrix protein, COMP-Ang-1), could be a novel class of antihypertensive agents that maintain endothelial integrity and function, thereby preventing the development of hypertension and target organ damage.

Methods And Results: To study the role of COMP-Ang-1 in preventing hypertension and target organ damage, a COMP-Ang-1 plasmid was electroporated into adductor muscles of 6 weeks old, pre-hypertensive, spontaneously hypertensive rats (SHRs), and the secretion of its expressed protein into the bloodstream was confirmed by western blotting.