Vessel Stability Research Articles

Accelerated and Improved Vascular Maturity after Transplantation of Testicular Tissue in Hydrogels Supplemented with VEGF- and PDGF-Loaded Nanoparticles.

Avascular transplantation of frozen–thawed testicular tissue fragments represents a potential future technique for fertility restoration in boys with cancer. A significant loss of spermatogonia was observed in xeno-transplants of human tissue most likely due to the hypoxic period before revascularization. To reduce the effect of hypoxia–reoxygenation injuries, several options have already been explored, like encapsulation in alginate hydrogel and supplementation with nanoparticles delivering a necrosis inhibitor (NECINH) or VEGF. While these approaches improved short-term (5 days) vascular surfaces in grafts, neovessels were not maintained up to 21 days; i.e., the time needed for achieving vessel stabilization. To better support tissue grafts, nanoparticles loaded with VEGF, PDGF and NECINH were developed. Testicular tissue fragments from 4–5-week-old mice were encapsulated in calcium-alginate hydrogels, either non-supplemented (control) or supplemented with drug-loaded nanoparticles (VEGF-nanoparticles; VEGF-nanoparticles + PDGF-nanoparticles; NECINH-nanoparticles; VEGF-nanoparticles + NECINH-nanoparticles; and VEGF-nanoparticles + PDGF-nanoparticles + NECINH-nanoparticles) before auto-transplantation. Grafts were recovered after 5 or 21 days for analyses of tissue integrity (hematoxylin–eosin staining), spermatogonial survival (immuno-histo-chemistry for promyelocytic leukemia zinc finger) and vascularization (immuno-histo-chemistry for α-smooth muscle actin and CD-31). Our results showed that a combination of VEGF and PDGF nanoparticles increased vascular maturity and induced a faster maturation of vascular structures in grafts.

DPSCs treated by TGF-\u03b21 regulate angiogenic sprouting of three-dimensionally co-cultured HUVECs and DPSCs through VEGF-Ang-Tie2 signaling

BackgroundMaintaining the stability and maturation of blood vessels is of paramount importance for the vessels to carry out their physiological function. Smooth muscle cells (SMCs), pericytes, and mesenchymal stem cells (MSCs) are involved in the maturation process of the newly formed vessels. The aim of this study was to investigate whether transforming growth factor beta 1 (TGF-β1) treatment could enhance pericyte-like properties of dental pulp stem cells (DPSCs) and how TGF-β1-treated DPSCs for 7 days (T-DPSCs) stabilize the newly formed blood vessels.MethodsWe utilized TGF-β1 to treat DPSCs for 1, 3, 5, and 7 days. Western blotting and immunofluorescence were used to analyze the expression of SMC markers. Functional contraction assay was conducted to assess the contractility of T-DPSCs. The effects of T-DPSC-conditioned media (T-DPSC-CM) on human umbilical vein endothelial cell (HUVEC) proliferation and migration were examined by MTT, wound healing, and trans-well migration assay. Most importantly, in vitro 3D co-culture spheroidal sprouting assay was used to investigate the regulating role of vascular endothelial growth factor (VEGF)-angiopoietin (Ang)-Tie2 signaling on angiogenic sprouting in 3D co-cultured spheroids of HUVECs and T-DPSCs. Angiopoietin 2 (Ang2) and VEGF were used to treat the co-cultured spheroids to explore their roles in angiogenic sprouting. Inhibitors for Tie2 and VEGFR2 were used to block Ang1/Tie2 and VFGF/VEGFR2 signaling.ResultsWestern blotting and immunofluorescence showed that the expression of SMC-specific markers (α-SMA and SM22α) were significantly increased after treatment with TGF-β1. Contractility of T-DPSCs was greater compared with that of DPSCs. T-DPSC-CM inhibited HUVEC migration. In vitro sprouting assay demonstrated that T-DPSCs enclosed HUVECs, resembling pericyte-like cells. Compared to co-culture with DPSCs, a smaller number of HUVEC sprouting was observed when co-cultured with T-DPSCs. VEGF and Ang2 co-stimulation significantly enhanced sprouting in HUVEC and T-DPSC co-culture spheroids, whereas VEGF or Ang2 alone exerted insignificant effects on HUVEC sprouting. Blocking Tie2 signaling reversed the sprouting inhibition by T-DPSCs, while blocking VEGF receptor (VEGFR) signaling boosted the sprouting inhibition by T-DPSCs.ConclusionsThis study revealed that TGF-β1 can induce DPSC differentiation into functional pericyte-like cells. T-DPSCs maintain vessel stability through Ang1/Tie2 and VEGF/VEGFR2 signaling.

Notch regulates vascular collagen IV basement membrane through modulation of lysyl hydroxylase 3 trafficking

Collagen type IV (Col IV) is a basement membrane protein associated with early blood vessel morphogenesis and is essential for blood vessel stability. Defects in vascular Col IV deposition are the basis of heritable disorders, such as small vessel disease, marked by cerebral hemorrhage and drastically shorten lifespan. To date, little is known about how endothelial cells regulate the intracellular transport and selective secretion of Col IV in response to angiogenic cues, leaving a void in our understanding of this critical process. Our aim was to identify trafficking pathways that regulate Col IV deposition during angiogenic blood vessel development. We have identified the GTPase Rab10 as a major regulator of Col IV vesicular trafficking during vascular development using both in vitro imaging and biochemistry as well as in vivo models. Knockdown of Rab10 reduced de novo Col IV secretion in vivo and in vitro. Mechanistically, we determined that Rab10 is an indirect mediator of Col IV secretion, partnering with atypical Rab25 to deliver the enzyme lysyl hydroxylase 3 (LH3) to Col IV-containing vesicles staged for secretion. Loss of Rab10 or Rab25 results in depletion of LH3 from Col IV-containing vesicles and rapid lysosomal degradation of Col IV. Furthermore, we demonstrate that Rab10 is Notch responsive, indicating a novel connection between permissive Notch-based vessel maturation programs and vesicle trafficking. Our results illustrate both a new trafficking-based component in the regulated secretion of Col IV and how this vesicle trafficking program interfaces with Notch signaling to fine-tune basement membrane secretion during blood vessel development.

Role of Notch in endothelial biology.

The Notch signalling pathway is one of the main regulators of endothelial biology. In the last 20years the critical function of Notch has been uncovered in the context of angiogenesis, participating in tip-stalk specification, arterial-venous differentiation, vessel stabilization, and maturation processes. Importantly, pharmacological compounds targeting distinct members of the Notch signalling pathway have been used in the clinics for cancer therapy. However, the underlying mechanisms that support the variety of outcomes triggered by Notch in apparently opposite contexts such as angiogenesis and vascular homeostasis remain unknown. In recent years, advances in -omics technologies together with mosaic analysis and high molecular, cellular and temporal resolution studies have allowed a better understanding of the mechanisms driven by the Notch signalling pathway in different endothelial contexts. In this review we will focus on the main findings that revisit the role of Notch signalling in vascular biology. We will also discuss potential future directions and technologies that will shed light on the puzzling role of Notch during endothelial growth and homeostasis. Addressing these open questions may allow the improvement and development of therapeutic strategies based on modulation of the Notch signalling pathway.

Integrating Microfluidic Models with Hemoglobin‐Based Oxygen Carriers for Investigating Oxygen‐Mediated Endothelial Function

Inadequate oxygen delivery to tissue, or hypoxia, is caused by extensive abnormalities in the structure and function of the vascular network. Hypoxia also has a significant role in vascular diseases such as stroke, pregnancy disorders, and cancer. Despite its prevalence, there is no established method for alleviating hypoxia and its deleterious effects to vascular function. Existing experimental models are incapable of enabling cellular and intercellular microcirculatory measurements while also controlling the local oxygen environment, impeding our ability to mechanistically study these effects. Hemoglobin-based oxygen carriers (HBOCs) are a promising class of red blood cell substitute which have been well characterized for transfusion medicine applications, yet little has been done to study the effects of HBOC administration on vascular function at the cellular level. In this work, we put forth a novel integration of microfluidic vascular models with HBOCs to investigate the effects of oxygen transport in microcirculation in vitro. We hypothesize that alleviating hypoxia with HBOCs restores normal blood vessel structure and function. We fabricated fully-lumenized microvessels in vitro which mimic post-capillary venules. We assessed vessel stability by immunofluorescence staining, and permeability under environmentally-controlled normoxic and hypoxic conditions. We then synthesized polymerized hemoglobin (PolyHb), an HBOC with favorable molecular weight and oxygen-carrying properties to alleviate hypoxia while minimizing extravasation and subsequent toxicity. We validated that PolyHb may be synthesized under varying conditions to selectively control the HBOC size and oxygen affinity, demonstrating that these properties can be modified to enable favorable oxygen transport and may be varied based on the desired application. As compared to previous generation HBOCs, PolyHb can attain molecular weights which will enable intravascular circulation to minimize toxicity, making PolyHb an ideal candidate for microfluidic investigation into the physiological effects of rescuing hypoxia. In future work, we will perfuse PolyHb through the engineered microvessels at constant flow and physiological shear stress levels to assess the ability of PolyHb to relieve induced hypoxia under imposed circumferential and longitudinally oriented hypoxia gradients.

THE PROTECTIVE EFFECT AND MECHANISM OF HSP47 IN HYPERTENSIVE INTRACEREBRAL HEMORRHAGE

Objective: Hypertensive intracerebral hemorrhage (ICH) has a high mortality rate, but there is no effective treatment,so how to prevent it has become a top priority. Heat shock protein 47 (HSP47) is a molecular chaperone for collagen synthesis and is responsible for transporting procollagen from the endoplasmic reticulum to the golgi lumen, effectively maintaining the three-dimensional structure of collagen. Absence of HSP47 may affect collagen synthesis and the stability of extracellular matrix (ECM), further damaging the stability of blood vessels. Therefore, we aimed to explore the role of HSP47 in ICH. Design and method: Spontaneous hypertensive ICH of mice were induced by angiotensin II and L-NAME We found that the level of HSP47 gradually decreased with the increase of modelling days. The adeno-associated virus was delivered into brain by stereotactic injection to overexpress HSP47. Results: The incidence of ICH were decreased significantly in mice by HSP47 overexpression. At the same time, the number and size of ICH in mice were significantly reduced. Experimental results show that HSP47 overexpression was sufficient to enhance ECM integrity and reduce VSMC apoptosis before ICH. Conclusions: These results suggest that HSP47 may have a protective effect on hypertensive ICH. Therefore, we emphasize that overexpression of HSP47 may be a new strategy for clinical treatment of hypertensive ICH.

Microvascular cells: A special focus on heterogeneity of pericytes in diabetes associated complications.

Pericytes (PC) are microvascular mural cells that make specific cell-to-cell contacts with the endothelial cells (EC). These cells are obligatory constituents of the microvessels including the retinal vasculature and they serve as regulators of vascular development, stabilization, maturation and remodeling. During early stages of diabetic retinopathy (DR), apoptotic loss of PC surrounding the retinal vasculature occurs. This may lead to reduced vessel stability, the onset of EC apoptosis, and subsequent retinal ischemia leading to angiogenesis and eventually, severe vision loss due to late proliferative diabetic retinopathy (PDR). Similarly, diabetic nephropathy (DN) is a chronic kidney disease due to hyperglycemia that particularly affects renal PC. Chronic high blood glucose level causes migration of peritubular PC away from the capillary into the interstitial space, which destabilizes the micro vessels, resulting in microvascular rarefaction. In both diabetes associated complications, the identification of specific biomarkers is necessary to stabilize the PC at an early stage. This review largely covers the importance of PC towards the pathogenesis of diabetes associated complications, and their heterogeneity in healthy and angiogenic vasculature.

Cellular mitosis predicts vessel stability in a mechanochemical model of sprouting angiogenesis.

Angiogenesis, the formation of new vessels, occurs in both developmental and pathological contexts. Prior research has investigated vessel formation to identify cellular phenotypes and dynamics associated with angiogenic disease. One major family of proteins involved in angiogenesis are the Rho GTPases, which govern function related to cellular elongation, migration, and proliferation. Using a mechanochemical model coupling Rho GTPase activity and cellular and intercellular mechanics, we investigate the role of cellular mitosis on sprouting angiogenesis. Mitosis-GTPase synchronization was not a strong predictor of GTPase and thus vessel signaling instability, whereas the location of mitotic events was predicted to alter GTPase cycling instabilities. Our model predicts that middle stalk cells undergoing mitosis introduce irregular dynamics in GTPase cycling and may provide a source of aberrant angiogenesis. We also find that cellular and junctional tension exhibit spatial heterogeneity through the vessel, and that tension feedback, specifically in stalk cells, tends to increase the maximum forces generated in the vessel.

Robust smooth control for global uniform asymptotic stabilization of underactuated surface vessels with unknown model parameters

AbstractThis paper investigates how to design controllers to stabilize the underactuated surface vessel to desired constant location and orientation with vanishing velocities. The first control law is designed as a smooth function of position and orientation errors without using model parameters, where a gain is made time‐varying to get over the nonholonomic constraint on model. Skew‐symmetric and damping terms in model are exploited to help construct two particular Lyapunov functions, and Barbalat's lemma are combined to verify the global uniform asymptotic convergence of errors and velocities. Then, the second and the third control laws are devised as the forms of the first controller plus velocity feedbacks and can achieve the same stability as the first one but have a weaker gain condition. All the three controllers are robust to model parameters due to their absence in controllers and only require three model parameters' upper/lower bounds, decreasing the identification workload greatly. Moreover, they are the first smooth ones capable of achieving global uniform asymptotic full‐state stabilization control of vessel with unknown model parameters. Effectiveness of the proposed controllers is demonstrated by numerical simulations.

The progression of intracerebral hemorrhage (ICH) is related to the expression of integrin \u03921 (ITGB1)

BackgroundIntracerebral hemorrhage (ICH) is fatal and detrimental to quality of life. Clinically, options for monitoring are often limited, potentially missing subtle neurological changes. Integrin β 1 (ITGB1) and β 3 (ITGB3) are the main components of integrin family receptors, which regulate the formation and stability of blood vessels. This study explored the relationship between the expression of ITGB1 and ITGB3 in intracerebral hemorrhage (ICH) to analyze their functional and clinical relevance.MethodsThe expression of ITGB1 and ITGB3 in ICH was accomplished by immunohistochemical (IHC) staining and western blotting (WB) analysis, respectively.ResultsFurthermore, the results demonstrated that ITGB1 was expressed in ICH tissues, but ITGB3 was not expressed in ICH tissues.ConclusionsIn summary, the clinical progression of ICH was related to the expression of ITGB1. ITGB1 may be a potential biomarker and contribute to the treatment of ICH.

An In Vitro Co-Culture Model of Bone Marrow Mesenchymal Stromal Cells and Peripheral Blood Mononuclear Cells Promotes the Differentiation of Myeloid Angiogenic Cells and Pericyte-Like Cells.

Mesenchymal stromal cells (MSCs) are known to stimulate the survival and growth of endothelial cells (ECs) by producing paracrine signals, as well as to differentiate into pericytes and thereby support blood vessel formation and stability. On the other hand, cells with an EC-like phenotype have been found within the CD14+ and CD34+ cell populations of peripheral blood (PB) mononuclear cells (MNCs). The aim of this study was to investigate the proangiogenic differentiation potential of human MSC-MNC co-cultures. Bone marrow-derived MSCs (2,500 cells/cm2) were co-cultured with MNCs (50,000 cells/cm2), which were isolated from the PB of healthy donors. MSCs and MNCs cultured alone at same cell densities were used as controls. Cells in MNC fraction and in co-cultures were isolated for CD14, CD34, and CD31 surface markers with magnetic-activated cell sorting. Co-cultures were analyzed for cell proliferation and morphology, as well as for the expression of various hematopoietic, endothelial, and pericyte markers by immunocytochemistry, quantitative PCR (qPCR), and flow cytometry. Vascular endothelial growth factor (VEGF) expression and secretion was measured with qPCR and enzyme-linked immunosorbent assay, respectively. Our results show that in co-cultures with MSCs, CD14+CD45+ MNCs differentiated into spindle-shaped, nonproliferative, EC-like, myeloid angiogenic cells (MACs) expressing CD31, but also into pericyte-like cells expressing neural/glial antigen 2 (NG2) and CD146. Functionality of the isolated MACs was demonstrated in co-cultures with human umbilical vein endothelial cells, where they supported the formation of tube-like structures. NG2+ cells of MNC-origin were found among both CD34-CD14+ and CD34-CD14- cell populations, indicating the existence of different subtypes of pericyte-like cells. In addition, VEGF was shown to be secreted in MSC-MNC co-cultures, mainly by MSCs. In conclusion, MSCs were shown to possess proangiogenic capacity in MSC-MNC co-cultures as they supported the differentiation of functional MACs, as well as the differentiation of pericyte-like cells of MNC origin. This phenomenon was mediated at least partially via secreted VEGF.

Experimental and numerical investigation on the load stability of coal cargoes during marine transport

During marine transport of coal commodities, cargo slip or liquefaction failure scenarios within the hold may occur under cyclic ship motions. The resulting cargo shift affects the vessel stability, and subsequently endangers goods and crews on board the vessel. This study aims to investigate the coal cargo stability under marine transport conditions. A suite of six coal samples was selected to undertake a series of undrained cyclic triaxial tests to investigate their liquefaction resistance. Results were subsequently compared to the liquefaction threshold advised by International Maritime Organisation. It was suggested that finer coals were observed to be more susceptible to liquefaction. In addition, discrete element modelling of the coal cargoes was conducted to study the cargo slip susceptibility. Calibration was performed to ensure materials modelled in the numerical program reflected the physical behaviours. Results indicated coarser coal samples with lower moisture contents exhibited cargo slip failures under nominated rolling ship motion. Nevertheless, resulting centre of gravity shift from cargo slip exhibited negligible effect on the cargo stability. Outcomes of this study provided important safety guidelines on marine transportation of coal commodities.

CU06-1004-Induced Vascular Normalization Improves Immunotherapy by Modulating Tumor Microenvironment via Cytotoxic T Cells.

Blocking the immune evasion mechanism of tumor cells has become an attractive means for treating cancers. However, the usage of a drug such as nivolumab (αPD-1), which blocks programmed cell death protein 1 (PD-1), turned out to be only effective against certain types of cancer. Especially, vascular abnormal structures of which deter delivery route by leakage and cause the poor perfusion were considered to be environment unfavorable to T cells and immune checkpoint blockade (ICB) delivery within the tumor microenvironment (TME). Herein, we report stabilization of tumor blood vessels by endothelial dysfunctional blocker CU06-1004, which modified the TME and showed synergistic effects with immunotherapy anti-PD-1 antibody. CU06-1004 combination therapy consistently prolonged the survival of tumor-bearing mice by decreasing tumor growth. T-cell infiltration increased in the tumors of the combination group, with cytotoxic CD8+ T cell activity within the tumor parenchyma upregulated compared with anti-PD-1 monotherapy. Tumor inhibition was associated with reduced hypoxia and reduced vessel density in the central region of the tumor. These effects correlated significantly with enhanced expression of IFN gamma and PD-L1 in tumors. Taken together, our findings suggest that CU06-1004 is a potential candidate drug capable of improving therapeutic efficacy of anti-PD-1 through beneficial changes in the TME.

Implementation of Pericytes in Vascular Regeneration Strategies.

For the survival and integration of complex large-sized tissue-engineered (TE) organ constructs that exceed the maximal nutrients and oxygen diffusion distance required for cell survival, graft (pre)vascularization to ensure medium or blood supply is crucial. To achieve this, the morphology and functionality of the microcapillary bed should be mimicked by incorporating vascular cell populations, including endothelium and mural cells. Pericytes play a crucial role in microvascular function, blood vessel stability, angiogenesis, and blood pressure regulation. In addition, tissue-specific pericytes are important in maintaining specific functions in different organs, including vitamin A storage in the liver, renin production in the kidneys and maintenance of the blood-brain-barrier. Together with their multipotential differentiation capacity, this makes pericytes the preferred cell type for application in TE grafts. The use of a tissue-specific pericyte cell population that matches the TE organ may benefit organ function. In this review, we provide an overview of the literature for graft (pre)-vascularization strategies and highlight the possible advantages of using tissue-specific pericytes for specific TE organ grafts. Impact statement The use of a tissue-specific pericyte cell population that matches the tissue-engineered (TE) organ may benefit organ function. In this review, we provide an overview of the literature for graft (pre)vascularization strategies and highlight the possible advantages of using tissue-specific pericytes for specific TE organ grafts.

Active control synthesis of nonlinear pitch-roll motions for marine vessels

This paper investigates the dynamical analysis and control synthesis for fractional-order pitch-roll system of marine vessels under regular waves. Suppression of the effects of roll and pitch motions is critical in improving maneuverability and stability of marine vessels with ensuring the safety of cargo and comfort to sailors. The pitch-roll mode shows complex behaviours such as period-2 motion, symmetry-breaking, torus attractor, and resonance depending on initial conditions, natural frequencies, wave frequencies, and wave amplitudes. Specifically, the nonlinear behaviours are characterized by phase portraits, bifurcation diagrams, and stability analysis. The nonlinear vibration patterns are observed even under regular waves because the pitch-roll motions are strongly coupled with two perpendicular directions. To secure the upright position of the vessels in heavy weather, adaptive fractional-order sliding mode control (AFOSMC) scheme has been employed to effectively regulate pitch-roll modes against extreme sea states. The closed stability of the ship pitch-roll system has been guaranteed by the Lyapunov theory. Numerical simulations have been extensively conducted to validate the effectiveness of the proposed control algorithms. To design more comfortable and safe vessels, this study presents pitch-roll resonance eliminations, stabilization and the challenges associated with robust vessel design.

Matricellular Protein SPARCL1 Regulates Blood Vessel Integrity and Antagonizes Inflammatory Bowel Disease.

BackgroundThe understanding of vascular plasticity is key to defining the role of blood vessels in physiologic and pathogenic processes. In the present study, the impact of the vascular quiescence marker SPARCL1 on angiogenesis, capillary morphogenesis, and vessel integrity was evaluated.MethodsAngiogenesis was studied using the metatarsal test, an ex vivo model of sprouting angiogenesis. In addition, acute and chronic dextran sodium sulfate colitis models with SPARCL1 knockout mice were applied.ResultsThis approach indicated that SPARCL1 inhibits angiogenesis and supports vessel morphogenesis and integrity. Evidence was provided that SPARCL1-mediated stabilization of vessel integrity counteracts vessel permeability and inflammation in acute and chronic dextran sodium sulfate colitis models. Structure-function analyses of purified SPARCL1 identified the acidic domain of the protein necessary for its anti-angiogenic activity.ConclusionsOur findings inaugurate SPARCL1 as a blood vessel–derived anti-angiogenic molecule required for vessel morphogenesis and integrity. SPARCL1 opens new perspectives as a vascular marker of susceptibility to colitis and as a therapeutic molecule to support blood vessel stability in this disease.

Engineering Extracellular Vesicles for Cancer Therapy.

Extracellular vesicles (EVs) are lipid bilayer containing nanovesicles that have a predominant role in intercellular communication and cargo delivery. EVs have recently been used as a means for drug delivery and have been depicted to elicit no or minimal immune response in vivo. The stability, biocompatibility and manipulatable tumour homing capabilities of these biological vessels make them an attractive target for the packaging and delivery of drugs and molecules to treat various diseases including cancer. The following chapter will summarise current EV engineering techniques for the purpose of delivering putative drugs and therapeutic molecules for the treatment of cancer. The relevance of EV source will be discussed, as well as the specific modifications required to manufacture them into suitable vehicles for molecular drug delivery. Furthermore, methods of EV cargo encapsulation will be evaluated with emphasis on intercellular coordination to allow for the effective emptying of therapeutic contents into target cells. While EVs possess properties making them naturally suitable nanocarriers for drugs and molecules, many challenges with clinical translation of EV-based platforms remain. These issues need to be addressed in order to harness the true potential of the EV-based therapeutic avenue.

Tumor Microenvironment-Associated Pericyte Populations May Impact Therapeutic Response in Thyroid Cancer.

Thyroid cancer is the most common endocrine malignancy, and aggressive radioactive iodine refractory thyroid carcinomas still lack an effective treatment. A deeper understanding of tumor heterogeneity and microenvironment will be critical to establishing new therapeutic approaches. One of the important influencing factors of tumor heterogeneity is the diversity of cells in the tumor microenvironment. Among these are pericytes, which play an important role in blood vessel stability and angiogenesis, as well as tumor growth and metastasis. Pericytes also have stem cell-like properties and are a heterogeneous cell population, and their lineage, which has been challenging to define, may impact tumor resistance at different tumor stages. Pericytes are also important stroma cell types in the angiogenic microenvironment which express tyrosine-kinase (TK) pathways (e.g., PDGFR-β). Although TK inhibitors (TKI) and BRAFV600E inhibitors are currently used in the clinic for thyroid cancer, their efficacy is not durable and drug resistance often develops. Characterizing the range of distinct pericyte populations and distinguishing them from other perivascular cell types may enable the identification of their specific functions in the thyroid carcinoma vasculature. This remains an essential step in developing new therapeutic strategies. Also, assessing whether thyroid tumors hold immature and/or mature vasculature with pericyte populations coverage may be key to predicting tumor response to either targeted or anti-angiogenesis therapies. It is also critical to apply different markers in order to identify pericyte populations and characterize their cell lineage. This chapter provides an overview of pericyte ontogenesis and the lineages of diverse cell populations. We also discuss the role(s) and targeting of pericytes in thyroid carcinoma, as well as their potential impact on precision targeted therapies and drug resistance.

New data in a mouse model of spontaneous choroidal neovascularisation support the role of angiopoietin‐2 inhibition in driving sustained vascular stabilisation and reduced fibrosis progression

PurposeTo explore the vessel stabilisation potential of dual angiopoietin‐2 (Ang‐2)/vascular endothelial growth factor‐A (VEGF‐A) inhibition in a mouse model of spontaneous choroidal neovascularisation (sCNV) in the context of phase 2 clinical data on faricimab, a bispecific antibody that binds to and neutralises both Ang‐2 and VEGF‐A.MethodsSeven‐week‐old JR5558 mice, developing sCNV in both eyes, were treated intraperitoneally with mouse cross‐reactive tool antibodies against Ang‐2, VEGF‐A, or both (bispecific antibody VA2); n = 7–15 mice per group. Fluorescein angiography (FA)‐evaluated CNV leakage and fibronectin (fibrosis marker) deposition on the retinal pigment epithelium (RPE)/choroid and around CNV lesions were assessed at baseline and 1 (PT1), 3 (PT2) and 5 weeks (PT3) post treatment to assess the effects on CNV lesion activity relative to untreated/IgG‐exposed mice.ResultsAnti‐Ang‐2‐, anti‐VEGF‐A‐ and VA2‐treated mice showed a significant reduction in CNV leakage (p < 0.05 to p < 0.001) versus controls at PT1, maintained only in anti‐Ang‐2‐ and VA2‐treated mice at PT2/3 (p < 0.05 to p < 0.0001). Lesions treated with anti‐VEGF alone showed reactivation on FA at PT2. The area of fibronectin staining on RPE/choroid and around lesions was significantly reduced with VA2 (38%; p < 0.01) and anti‐Ang‐2 (41%; p < 0.001) versus IgG control at PT1; the effect of VEGF‐A inhibition alone was not significant. At PT2 and PT3, only VA2 inhibition showed significant reduction in fibronectin staining over both control groups (by 47%; p < 0.01 and 54%; p < 0.05, respectively).ConclusionsFaricimab's potential for extended durability observed in phase 2 clinical trials was further explored in a mouse model of sCNV. CNV leakage and fibronectin staining around CNV lesions were suppressed for longer with dual Ang‐2/VEGF‐A inhibition versus VEGF‐A alone. These findings support the hypothesis that the sustained efficacy of faricimab observed in phase 2 trials is due to vessel‐stabilising effects driven by Ang‐2 inhibition.

Angiopoietin-2 Promotes Inflammatory Activation in Monocytes of Systemic Sclerosis Patients

Angiopoietin-2 (Ang-2), a ligand of the tyrosine kinase receptor Tie2, is essential for vascular development and blood vessel stability and is also involved in monocyte activation. Here, we examined the role of Ang-2 on monocyte activation in patients with systemic sclerosis (SSc). Ang-2 levels were measured in serum and skin of healthy controls (HCs) and SSc patients by ELISA and array profiling, respectively. mRNA expression of ANG2 was analyzed in monocytes, dermal fibroblasts, and human pulmonary arterial endothelial cells (HPAECs) by quantitative PCR. Monocytes were stimulated with Ang-2, or with serum from SSc patients in the presence of a Tie2 inhibitor or an anti-Ang2 neutralizing antibody. Interleukin (IL)-6 and IL-8 production was analyzed by ELISA. Ang-2 levels were elevated in the serum and skin of SSc patients compared to HCs. Importantly, serum Ang-2 levels correlated with clinical disease parameters, such as skin involvement. Lipopolysaccharide (LPS) LPS, R848, and interferon alpha2a (IFN-α) stimulation up-regulated the mRNA expression of ANG2 in monocytes, dermal fibroblasts, and HPAECs. Finally, Ang-2 induced the production of IL-6 and IL-8 in monocytes of SSc patients, while the inhibition of Tie2 or the neutralization of Ang-2 reduced the production of both cytokines in HC monocytes stimulated with the serum of SSc patients. Therefore, Ang-2 induces inflammatory activation of SSc monocytes and neutralization of Ang-2 might be a promising therapeutic target in the treatment of SSc.