Endothelial Progenitor Research Articles

Wnt signaling mediates acquisition of blood-brain barrier properties in naïve endothelium derived from human pluripotent stem cells.

Endothelial cells (ECs) in the central nervous system (CNS) acquire their specialized blood-brain barrier (BBB) properties in response to extrinsic signals, with Wnt/β-catenin signaling coordinating multiple aspects of this process. Our knowledge of CNS EC development has been advanced largely by animal models, and human pluripotent stem cells (hPSCs) offer the opportunity to examine BBB development in an in vitro human system. Here, we show that activation of Wnt signaling in hPSC-derived naïve endothelial progenitors, but not in matured ECs, leads to robust acquisition of canonical BBB phenotypes including expression of GLUT-1, increased claudin-5, decreased PLVAP, and decreased permeability. RNA-seq revealed a transcriptome profile resembling ECs with CNS-like characteristics, including Wnt-upregulated expression of LEF1, APCDD1, and ZIC3. Together, our work defines effects of Wnt activation in naïve ECs and establishes an improved hPSC-based model for interrogation of CNS barriergenesis.

Engineering injectable vascularized tissues from the bottom-up: Dynamics of in-gel extra-spheroid dermal tissue assembly

Modular tissue engineering approaches open up exciting perspectives for the biofabrication of vascularized tissues from the bottom-up, using micro-sized units such as spheroids as building blocks. While several techniques for 3D spheroid formation from multiple cell types have been reported, strategies to elicit the extra-spheroid assembly of complex vascularized tissues are still scarce. Here we describe an injectable approach to generate vascularized dermal tissue, as an example application, from spheroids combining fibroblasts and endothelial progenitors (OEC) in a xeno-free (XF) setting. Short-term cultured spheroids (1 day) were selected over mature spheroids (7 days), as they showed significantly higher angiogenic sprouting potential. Embedding spheroids in fibrin was crucial for triggering cell migration into the external milieu, while providing a 3D framework for in-gel extra-spheroid morphogenesis. Migrating fibroblasts proliferated and produced endogenous ECM forming a dense tissue, while OEC self-assembled into stable capillaries with lumen and basal lamina. Massive in vitro interconnection between sprouts from neighbouring spheroids rapidly settled an intricate vascular plexus. Upon injection into the chorioallantoic membrane of chick embryos, fibrin-entrapped pre-vascularized XF spheroids developed into a macrotissue with evident host vessel infiltration. After only 4 days, perfused chimeric capillaries with human cells were present in proximal areas, showing fast and functional inosculation between host and donor vessels. This method for generating dense vascularized tissue from injectable building blocks is clinically relevant and potentially useful for a range of applications.

Nonbone Marrow CD34+ Cells Are Crucial for Endothelial Repair of Injured Artery.

[Figure: see text].

A Feasibility Study on 3D Bioprinting of Microfat Constructs Towards Wound Healing Applications.

Chronic wounds affect over 400,000 people in the United States alone, with up to 60,000 deaths each year from non-healing ulcerations. Tissue grafting (e.g., autografts, allografts, and xenografts) and synthetic skin substitutes are common treatment methods, but most solutions are limited to symptomatic treatment and do not address the underlying causes of the chronic wound. Use of fat grafts for wound healing applications has demonstrated promise but these grafts suffer from low cell viability and poor retention at the wound site resulting in suboptimal healing of chronic wounds. Herein, we report on an innovative closed-loop fat processing system (MiniTCTM) that can efficiently process lipoaspirates into microfat clusters comprising of highly viable regenerative cell population (i.e., adipose stromal cells, endothelial progenitors) preserved in their native niche. Cryopreservation of MiniTCTM isolated microfat retained cell count and viability. To improve microfat retention and engraftment at the wound site, microfat was mixed with methacrylated collagen (CMA) bioink and 3D printed to generate microfat-laden collagen constructs. Modulating the concentration of microfat in CMA constructs had no effect on print fidelity or stability of the printed constructs. Results from the Alamar blue assay showed that the cells remain viable and metabolically active in microfat-laden collagen constructs for up to 10 days in vitro. Further, quantitative assessment of cell culture medium over time using ELISA revealed a temporal expression of proinflammatory and anti-inflammatory cytokines indicative of wound healing microenvironment progression. Together, these results demonstrate that 3D bioprinting of microfat-laden collagen constructs is a promising approach to generate viable microfat grafts for potential use in treatment of non-healing chronic wounds.

An efficient method to generate kidney organoids at the air-liquid interface.

The prevalence of kidney dysfunction continues to increase worldwide, driving the need to develop transplantable renal tissues. The kidney develops from four major renal progenitor populations: nephron epithelial, ureteric epithelial, interstitial and endothelial progenitors. Methods have been developed to generate kidney organoids but few or dispersed tubular clusters within the organoids hamper its use in regenerative applications. Here, we describe a detailed protocol of asynchronous mixing of kidney progenitors using organotypic culture conditions to generate kidney organoids tightly packed with tubular clusters and major renal structures including endothelial network and functional proximal tubules. This protocol provides guidance in the culture of human embryonic stem cells from a National Institute of Health-approved line and their directed differentiation into kidney organoids. Our 18-day protocol provides a rapid method to generate kidney organoids that facilitate the study of different nephrological events including in vitro tissue development, disease modeling and chemical screening. However, further studies are required to optimize the protocol to generate additional renal-specific cell types, interconnected nephron segments and physiologically functional renal tissues.

A study focused on macrophages modulation induced by the Polymeric Electrospun Matrices (EL-Ms) for application in tissue regeneration: In vitro proof of concept

A successful regenerative process has to consider the role of immune system after surgical implantation of a polymer-based matrix due to the reaction of monocytes and macrophages cells after contact with biomaterial. Pro-inflammatory (TNF-alfa, IL-6 and IL-8) and anti-inflammatory (IL-10) cytokines released by macrophages cells are fundamental in acute inflammatory response (2–3 days) to destroy pathogens and help scaffold during regenerative process supporting the up-regulation of ECM and endothelial progenitor cells.Aim of this work was to evaluate the in vitro acute response induced by pre-optimized polymeric electrospun matrices (EL-Ms), after 3 days contact with macrophages (M0) and EL-Ms ability to modulate M1 and/or M2 macrophages polarization.Biological characterization included MTT, LDH and Live/Dead assays, immunological characterization by ELISA for cytokine-expression levels determination. Morphological characterization was carried out by Confocal Laser Scanning Microscopy and Scanning Electron Microscopy.The results showed an initial pro-inflammatory response (after 24 h) characterized by release of TNF-alfa, IL-6 and IL-8 cytokines. A preferential anti-inflammatory response was highlighted after 72 h, demonstrated by higher release of IL-10 and elongation of macrophages in contact with EL-Ms, that is typical of M2 cell polarization.EL-Ms could be used as eligible support to enhance tissue regeneration promoting an anti-inflammatory response.

Immune response as a new player in mitral valve prolapse

Mitral valve prolapse (MVP) affects 3% of the population and is characterized by a myxomatous MV remodeling. The pathophysiological mechanisms involved in MVP remain elusive and the only therapeutic option is to perform MV surgery. The first causing mutation in MVP has been identified on the FLNA gene. We recently generated a KI rat for the FLNA-P637Q mutation that develops MVP. A recent RNA-seq analysis revealed an upregulation of genes involved in immune response and inflammation pathways in the valves of KI rats compared to WT. The aim of this study was then to identify and quantify the immune cells present in MVs and assess their role in the development and/or progression of the disease. Flow cytometry was used to quantify the hematopoietic cells (CD45), resident macrophages (CD206), myeloid lineage (CD11b), endothelial progenitors (CD34) and endothelial cells (CD31) in the MV of 3-weeks old KI and WT rats. The location of those cells within the MV tissues was analysed by immunofluorescence on cryosectioned MVs. Cytometry results showed a higher proportion of CD45+ and CD206+ cells in the KI rats compared to WT (20% vs. 14% and 28% vs. 16%, respectively) but similar proportion of CD31+ (14%). The CD45 and CD206 immunofluorescences performed on WT animals showed a clear localization of the positive cells on the edge of the atrial side of the leaflet, in the sub-endothelium layer. In KI rats, CD45+ and CD206+ cells were diffusely located: close to the atrial side of the MV leaflet, but also into the medial third of the leaflet. This preliminary study showed that recruitment of immune cells in MVP could be an important player in the pathophysiological process leading the disease. To elucidate the specific roles of this pathway, the temporal recruitment of immune cells and their specific activity need to be studied over the course of the disease progression.

HDL biodistribution and brain receptors in zebrafish, using HDLs as vectors for targeting endothelial cells and neural progenitors

High density lipoproteins (HDLs) display pleiotropic functions such as anti-inflammatory, antioxidant, anti-protease, and anti-apoptotic properties. These effects are mediated by four main receptors: SCARB1 (SR-BI), ABCA1, ABCG1, and CD36. Recently, HDLs have emerged for their potential involvement in brain functions, considering their epidemiological links with cognition, depression, and brain plasticity. However, their role in the brain is not well understood. Given that the zebrafish is a well-recognized model for studying brain plasticity, metabolic disorders, and apolipoproteins, it could represent a good model for investigating the role of HDLs in brain homeostasis. By analyzing RNA sequencing data sets and performing in situ hybridization, we demonstrated the wide expression of scarb1, abca1a, abca1b, abcg1, and cd36 in the brain of adult zebrafish. Scarb1 gene expression was detected in neural stem cells (NSCs), suggesting a possible role of HDLs in NSC activity. Accordingly, intracerebroventricular injection of HDLs leads to their uptake by NSCs without modulating their proliferation. Next, we studied the biodistribution of HDLs in the zebrafish body. In homeostatic conditions, intraperitoneal injection of HDLs led to their accumulation in the liver, kidneys, and cerebral endothelial cells in zebrafish, similar to that observed in mice. After telencephalic injury, HDLs were diffused within the damaged parenchyma and were taken up by ventricular cells, including NSCs. However, they failed to modulate the recruitment of microglia cells at the injury site and the injury-induced proliferation of NSCs. In conclusion, our results clearly show a functional HDL uptake process involving several receptors that may impact brain homeostasis and suggest the use of HDLs as delivery vectors to target NSCs for drug delivery to boost their neurogenic activity.

Bone regeneration associated with low-level laser therapy in implantology

Several therapies for tissue regeneration in implantology have been explored for their ability to enhance bone regeneration such as low-level laser therapy (LLLT), also known as photobiomodulation. This technique has been shown to reduce inflammation and edema, induce analgesia, and promote healing in a range of musculoskeletal pathologies with cost-effective for healing therapy. The endothelial progenitor and hematopoietic stem cells, together with LLLT improving their capacity to induce angiogenesis, recruit other cells to a site of injury and secrete growth factors and cytokines that have a paracrine effect on surrounding cells. A critical review and comprehensively analyze of tissue regeneration associated to newer regenerative techniques as LLLT, platelet derivatives and mesenchymal stem cells (MSCs) at preimplant sites was released. An electronic search in PubMed via Medline and Embase was conducted of publications from the previous 10 years. English language articles related to the subject were found using selected keywords. We summarize the photobiomodulation properties and its relation with platelet derivatives and MSCs and discuss the efficacy of these therapies for tissue repair. The LLLT is well-documented therapy but further research studies relating LLLT to tissue regeneration in periodontics and implantology are needed.

Cellular remodeling of fibrotic conduit as vascular graft

The replacement of small-diameter arteries remains an unmet clinical need. Here we investigated the cellular remodeling of fibrotic conduits as vascular grafts. The formation of fibrotic conduit around subcutaneously implanted mandrels involved not only fibroblasts but also the trans-differentiation of inflammatory cells such as macrophages into fibroblastic cells, as shown by genetic lineage tracing. When fibrotic conduits were implanted as vascular grafts, the patency was low, and many fibrotic cells were found in neointima. Decellularization and anti-thrombogenic coating of fibrotic conduits produced highly patent autografts that remodeled into neoarteries, offering an effective approach to obtain autografts for clinical therapy. While autografts recruited mostly anti-inflammatory macrophages for constructive remodeling, allogenic DFCs had more T cells and pro-inflammatory macrophages and lower patency. Endothelial progenitors and endothelial migration were observed during endothelialization. Cell infiltration into DFCs was more efficient than decellularized arteries, and infiltrated cells remodeled the matrix and differentiated into smooth muscle cells (SMCs). This work provides insight into the remodeling of fibrotic conduits, autologous DFCs and allogenic DFCs, and will have broad impact on using fibrotic matrix for regenerative engineering.

Abstract 341: Protective Role of Myeloid Cell-specific Erbb3 Signaling After Transverse Aortic Constriction

Introduction: Understanding molecular mechanisms underlying cardiac hypertrophy is crucial for protecting against cardiac remodeling, or slowing down its destined pathway to heart failure. Recent studies revealed that myeloid cells play an important role in the regulation of hypertrophic remodeling. Neuregulin-1 (NRG-1) has been shown to play an essential role in the regulation of tissue-protective and pro-survival processes in response to tissue injury in the cardiovascular system. We find that NRG-1 receptors, including ErbB2 and ErbB3, are expressed and functionally active in cardiac myeloid cells. We hypothesized that the NRG-1/ErbB3 signaling in myeloid cells plays a protective role in cardiac hypertrophic remodeling. To test this hypothesis, we examined the effect of Erbb3 gene ablation in mouse myeloid cells on cardiac hypertrophic remodeling induced by pressure overload. Methods and results: Myeloid-specific ErbB3-deficient mice (ErbB3 MyeKO ) were generated by crossing Erbb3 -floxed mice with LysM-Cre transgenic mice. Cardiac hypertrophic remodeling was established in mice by transverse aortic constriction (TAC). Five days after TAC, survival was dramatically reduced in male ErbB3 MyeKO mice (20% vs. 90%, p=0.021 , MyeKO vs. MyeWT). The post-mortem examination of lung weight to body weight ratio suggested that acute pulmonary edema was developed in ERBB3 MyeKO mice. In order to determine the cellular and molecular mechanisms involved in the increased mortality in ErbB3 MyeKO males, cardiac cell populations were examined at day 3 post-TAC using flow cytometry. A significant accumulation of myeloid cells was found in control but not in ErbB3 MyeKO males. This was accompanied by increased proliferation of Sca-1 positive non-immune cells (endothelial cells and cardiac progenitors) in control but not ErbB3 MyeKO males. An antibody-based protein array analysis revealed that IGF-1 expression was significantly downregulated only in ErbB3 MyeKO males after TAC. Conclusion: Our data highlight the important role of myeloid cell-specific ErbB3 signaling in the accumulation of myeloid cells that contributes to the development of compensatory hypertrophy and the prevention of acute heart failure in male mice.

Effect of 8-week resistance trainings in different environmental conditions on endothelial progenitor cells and some cardiovascular risk factors in overweight men

Background: Vascular endothelial dysfunction is pathological conditions that may be due to complications of obesity in various arteries. The purpose of this study was to investigate the effect of 8 weeks resistance training in different environmental conditions on endothelium progenitor cells (EPCS) (Marker of CD34), oxidized-LDL (oxLDL) and C-reactive protein (CRP) in overweight men. Methods: For this Purpose, 30 overweigh male students in Kermanshah city with the mean age of 19.8± 1.13 yr participated in this study, voluntarily. Subjects randomly assigned into 3 groups including hypoxic and normoxic resistance training, and hypoxic exposure. Participants performed the protocols 3 days per week for 8 weeks with 70% of 1RM. The oxLDL, CRP, and CD34 were measured before and after the intervention. T-test, one-Way ANOVA, Wilcoxon and Kruskal-Wallis tests were used to analyzing the data. Results: There was a significant decrease in CRP and oxLDL levels in the hypoxic resistance (P=0.001, P=0.005), normoxic resistance (P=0.003, P=0.013) and hypoxic exposure (P=0.003, P=0.005), respectively. However, no significant difference was observed between variations of the groups. The cells of CD34 was increased after the hypoxic resistance (P=0.005), normoxic resistance (P=0.005), and hypoxia exposure (P=0.004). No significant difference was observed between variations of the groups. Conclusion: Considering the similar effects of hypoxic exposure with other groups on study variables, it may be possible to use hypoxic exposure as a beneficial manner for some overweight individuals at the injury and special circumstances.

Pannexin-1 channel \u201cfuels\u201d by releasing ATP from bone marrow cells a state of sterile inflammation required for optimal mobilization and homing of hematopoietic stem cells

An efficient harvest of hematopoietic stem/progenitor cells (HSPCs) after pharmacological mobilization from the bone marrow (BM) into peripheral blood (PB) and subsequent proper homing and engraftment of these cells are crucial for clinical outcomes from hematopoietic transplants. Since extracellular adenosine triphosphate (eATP) plays an important role in both processes as an activator of sterile inflammation in the bone marrow microenvironment, we focused on the role of Pannexin-1 channel in the secretion of ATP to trigger both egress of HSPCs out of BM into PB as well as in reverse process that is their homing to BM niches after transplantation into myeloablated recipient. We employed a specific blocking peptide against Pannexin-1 channel and noticed decreased mobilization efficiency of HSPCs as well as other types of BM-residing stem cells including mesenchymal stroma cells (MSCs), endothelial progenitors (EPCs), and very small embryonic-like stem cells (VSELs). To explain better a role of Pannexin-1, we report that eATP activated Nlrp3 inflammasome in Gr-1+ and CD11b+ cells enriched for granulocytes and monocytes. This led to release of danger-associated molecular pattern molecules (DAMPs) and mitochondrial DNA (miDNA) that activate complement cascade (ComC) required for optimal egress of HSPCs from BM. On the other hand, Pannexin-1 channel blockage in transplant recipient mice leads to a defect in homing and engraftment of HSPCs. Based on this, Pannexin-1 channel as a source of eATP plays an important role in HSPCs trafficking.

679-P: Endothelial and Hematopoietic Progenitor Cells Are Reduced at Rest and Have an Attenuated Mobilization Response to Exercise in People with Type 1 Diabetes

Aims: Endothelial and Hematopoietic Progenitor Cells (EPCs and HPCs) promote vascular health through secreting proangiogenic factors and replacing damaged cells. Exercise has been shown to be a mobiliser of these rare cells in healthy individuals, however, the response in chronic diseases such as type 1 diabetes (T1D) is unclear. We compared EPC and HPC counts at rest and after acute exercise in people with and without T1D. Methods: Thirty T1D participants (38±12 years, HbA1c 58.5±9.3 mmol/mol-1, diabetes duration 20±13 years) and 30 age, sex, BMI and fitness matched non diabetes controls were recruited. After a maximal exercise test, participants attended a second visit to complete 45mins of walking at 60%VO2peak. Blood samples were taken at rest, immediately and 1 hour post exercise. Circulating levels of two HPCs and five EPC phenotypes were enumerated by flow cytometry. Data (mean±SD) were analysed by mixed model ANOVA and t-test with significance accepted at p≤0.05. Results: The T1D group had significantly lower rest count of HPCs and EPCs, ranging from 21 to 41% lower across all samples compared to the control. Exercise mobilized all cell phenotypes in both groups, with significant increases from rest to post exercise, while HPCs and CD34+CD31+ EPCs remained elevated 1hr post exercise. However, the change (Δ) in HPCs and EPCs from rest to post exercise was greater in the control versus T1D group, with higher CD34+CD45dim HPCs (p=0.03, Δ 48±65 vs. 24±33 cells/ml), as well as CD34+CD31+ (p=0.04, Δ 23±19 vs. 15±25 cells/ml) and CD34+VEGFR2+ EPCs (p=0.02, Δ 24 ±24 vs. 15±31 cells/ml). Conclusion: People with T1D have reduced numbers of HPCs and EPCs at rest and also display a blunted exercise induced increase in these rare blood vessel protecting cells. Further research is needed to understand the clinical significance of an attenuated exercise mobilization of these EPCs and HPCs phenotypes in predicting future cardiovascular complications in T1D. Disclosure G.S. Taylor: None. K. Smith: None. J. Scragg: None. A. Bashir: None. A. Flatt: None. E.J. Stevenson: None. J.A. Shaw: Advisory Panel; Self; Medtronic. Speaker’s Bureau; Self; Novo Nordisk A/S. M.D. Ross: None. D.J. West: None. Funding Diabetes Research & Wellness Foundation (to D.J.W.)

Eyeing the Extracellular Matrix in Vascular Development and Microvascular Diseases and Bridging the Divide between Vascular Mechanics and Function.

The extracellular matrix (ECM) is critical in all aspects of vascular development and health: supporting cell anchorage, providing structure, organization and mechanical stability, and serving as a sink for growth factors and sustained survival signals. Abnormal changes in ECM protein expression, organization, and/or properties, and the ensuing changes in vascular compliance affect vasodilator responses, microvascular pressure transmission, and collateral perfusion. The changes in microvascular compliance are independent factors initiating, driving, and/or exacerbating a plethora of microvascular diseases of the eye including diabetic retinopathy (DR) and vitreoretinopathy, retinopathy of prematurity (ROP), wet age-related macular degeneration (AMD), and neovascular glaucoma. Congruently, one of the major challenges with most vascular regenerative therapies utilizing localized growth factor, endothelial progenitor, or genetically engineered cell delivery, is the regeneration of blood vessels with physiological compliance properties. Interestingly, vascular cells sense physical forces, including the stiffness of their ECM, through mechanosensitive integrins, their associated proteins and the actomyosin cytoskeleton, which generates biochemical signals that culminate in a rapid expression of matricellular proteins such as cellular communication network 1 (CCN1) and CCN2 (aka connective tissue growth factor or CTGF). Loss or gain of function of these proteins alters genetic programs of cell growth, ECM biosynthesis, and intercellular signaling, that culminate in changes in cell behavior, polarization, and barrier function. In particular, the function of the matricellular protein CCN2/CTGF is critical during retinal vessel development and regeneration wherein new blood vessels form and invest a preformed avascular neural retina following putative gradients of matrix stiffness. These observations underscore the need for further in-depth characterization of the ECM-derived cues that dictate structural and functional properties of the microvasculature, along with the development of new therapeutic strategies addressing the ECM-dependent regulation of pathophysiological stiffening of blood vessels in ischemic retinopathies.

Cellular and Molecular Mechanisms of Kidney Development: From the Embryo to the Kidney Organoid.

Development of the metanephric kidney is strongly dependent on complex signaling pathways and cell–cell communication between at least four major progenitor cell populations (ureteric bud, nephron, stromal, and endothelial progenitors) in the nephrogenic zone. In recent years, the improvement of human-PSC-derived kidney organoids has opened new avenues of research on kidney development, physiology, and diseases. Moreover, the kidney organoids provide a three-dimensional (3D) in vitro model for the study of cell-cell and cell-matrix interactions in the developing kidney. In vitro re-creation of a higher-order and vascularized kidney with all of its complexity is a challenging issue; however, some progress has been made in the past decade. This review focuses on major signaling pathways and transcription factors that have been identified which coordinate cell fate determination required for kidney development. We discuss how an extensive knowledge of these complex biological mechanisms translated into the dish, thus allowed the establishment of 3D human-PSC-derived kidney organoids.

Increased mobilization of mesenchymal stem cells in patients with acute respiratory distress syndrome undergoing extracorporeal membrane oxygenation.

The acute respiratory distress syndrome (ARDS) is characterized by pulmonary epithelial and endothelial barrier dysfunction and injury. In severe forms of ARDS, extracorporeal membrane oxygenation (ECMO) is often the last option for life support. Endothelial progenitor (EPC) and mesenchymal stem cells (MSC) can regenerate damaged endothelium and thereby improve pulmonary endothelial dysfunction. However, we still lack sufficient knowledge about how ECMO might affect EPC- and MSC-mediated regenerative pathways in ARDS. Therefore, we investigated if ECMO impacts EPC and MSC numbers in ARDS patients. Peripheral blood mononuclear cells from ARDS patients undergoing ECMO (n = 16) and without ECMO support (n = 12) and from healthy volunteers (n = 16) were isolated. The number and presence of circulating EPC and MSC was detected by flow cytometry. Serum concentrations of vascular endothelial growth factor (VEGF) and angiopoietin 2 (Ang2) were determined. In the ECMO group, MSC subpopulations were higher by 71% compared to the non-ECMO group. Numbers of circulating EPC were not significantly altered. During ECMO, VEGF and Ang2 serum levels remained unchanged compared to the non-ECMO group (p = 0.16), but Ang2 serum levels in non-survivors of ARDS were significantly increased by 100% (p = 0.02) compared to survivors. ECMO support in ARDS is specifically associated with an increased number of circulating MSC, most likely due to enhanced mobilization, but not with a higher numbers of EPC or serum concentrations of VEGF and Ang2.

Primary Hemangiosarcoma of the Falciform Fat in Seven Dogs (2007-2015).

Canine hemangiosarcoma (HSA), a malignant neoplasm of vascular endothelial or bone marrow progenitor cell origin, most often affects the spleen, heart, and liver and typically has an aggressive biologic behavior. Canine HSA arising from the falciform fat/ligament represents a rare anatomic variant, with only two reports in the veterinary literature. In this study, we describe the clinical presentation, treatment, and outcome of seven dogs with primary HSA of the falciform ligament. Histologic grade and mitotic score were not significantly associated with outcome. All dogs had the primary tumor surgically excised except for one diagnosed at necropsy. Median overall survival for all dogs diagnosed prior to necropsy was 339 days, and the 1 yr survival rate was 50%. Four dogs were treated with adjuvant chemotherapy and had a significantly longer median overall survival (394 versus 83 days) than those that did not (P = .018). Dogs with HSA of the falciform ligament may have improved 1 yr survival rates and longer median survival time compared with dogs with HSA in more common visceral locations.

Toward the Clinical Application of Therapeutic Angiogenesis Against Pediatric Ischemic Retinopathy.

Therapeutic angiogenesis refers to strategies of inducing angiogenesis to treat diseases involving ischemic conditions. Historically, most attempts and achievements have been related to coronary and peripheral artery diseases. In this review, we propose the clinical application of therapeutic angiogenesis for the treatment of pediatric ischemic retinopathy, including retinopathy of prematurity, familial exudative retinopathy, and NDP-related retinopathy. These diseases are all characterized by the reduction of physiological angiogenesis and the following induction of pathological angiogenesis. Therapeutic angiogenesis, which supplements insufficient physiological angiogenesis, may be a therapeutic approach for ischemic conditions. Various molecules and modalities can be utilized to apply therapeutic angiogenesis for the treatment of ischemic retinopathy, as in coronary and peripheral artery diseases. Experiences with cardiovascular diseases provide a useful reference for the further clinical application of therapeutic angiogenesis in pediatric ischemic retinopathy. Recombinant proteins and gene therapy are powerful tools to deliver angiogenic factors to retinal tissues directly. Furthermore, endothelial progenitor or bone marrow-derived cells can be injected into the vitreous cavity of the eye for therapeutic angiogenesis. Intraocular injections are highly promising for the delivery of therapeutics for therapeutic angiogenesis. We expect that therapeutic angiogenesis will be a breakthrough in the treatment of pediatric ischemic retinopathy.

Endothelial Progenitor and Mesenchymal Stromal Cells in Newborns With Congenital Diaphragmatic Hernia Undergoing Extracorporeal Membrane Oxygenation.

Background: Endothelial progenitor (EPC) and mesenchymal stromal cells (MSC) can regenerate damaged endothelium and thereby improve pulmonary endothelial dysfunction. We do not know, how extracorporeal membrane oxygenation (ECMO) might affect EPC- and MSC-mediated regenerative pathways in patients with congenital diaphragmatic hernia (CDH). Therefore, we investigated, if ECMO support impacts EPC and MSC numbers in CDH patients.Methods: Peripheral blood mononuclear cells from newborns with ECMO-dependent (n = 18) and ECMO-independent CDH (n = 12) and from healthy controls (n = 12) were isolated. The numbers of EPC and MSC were identified by flowcytometry. Serum levels of vascular endothelial growth factor (VEGF) and angiopoietin (Ang)-2 were determined.Results: EPC and MSC were elevated in newborns with CDH. ECMO-dependent infants had higher EPC subpopulation counts (2,1–7,6-fold) before treatment compared to ECMO-independent infants. In the disease course, EPC and MSC subpopulation counts in ECMO-dependent infants were lower than before ECMO initiation. During ECMO, VEGF serum levels were significantly reduced (by 90.5%) and Ang2 levels significantly increased (by 74.8%).Conclusions: Our data suggest that ECMO might be associated with a rather impaired mobilization of EPC and MSC and with a depression of VEGF serum levels in newborns with CDH.