A Rare Location of Pseudoaneurysm in Subaortic Ring after Bentall Operation

Bentall operation is considered a gold standard of surgery in the treatment of ascending aortic aneurysm. This operation with en-bloc resection of ascending aorta and aortic valve requires aortic valve with two coronary bottoms re-replacements in a prepared composite graft. The four important locations for the pseudoaneurysm include proximal and distal composite graft anastomosis and two coronary bottom sites. However, many complications have been reported with this technique but the most serious complication associated with this operation is defined as pseudoaneurysm. We report an exceedingly rare case of subaortic ring pseudoaneurysm in retro composite graft position enclosed by infected surgical that was used to control bleeding in this location. Dehiscence occurred between the aortic ring and the underlying left ventricular muscle. The aortic ring was separated from the underlying muscle by the high tensile strength of sewing ring sutures. The pseudoaneurysm compressing the left atrium without communicating with any cardiac chamber and presenting with high fever (39°C), chills, a few months after Bentall operation. The patient underwent redo operation and repair of the dehiscence’s site. The 6-month follow-up revealed no recurrence of a pseudoaneurysm. The uniqueness of this case report is related to the site of pseudoaneurysm between the aortic ring and underlying left ventricular muscle that have not been reported in the medical literature so far.

Proangiogenic Effect of Affinin and an Ethanolic Extract from Heliopsis longipes Roots: Ex Vivo and In Vivo Evidence

Angiogenesis, the formation of new blood vessels, underlies tissue development and repair. Some medicinal plant-derived compounds can modulate the angiogenic response. Heliopsis longipes, a Mexican medicinal plant, is widely used because of its effects on pain and inflammation. The main bioactive phytochemicals from H. longipes roots are alkamides, where affinin is the most abundant. Scientific studies show various medical effects of organic extracts of H. longipes roots and affinin that share some molecular pathways with the angiogenesis process, with the vasodilation mechanism of action being the most recent. This study investigates whether pure affinin and the ethanolic extract from Heliopsis longipes roots (HLEE) promote angiogenesis. Using the aortic ring rat assay (ex vivo method) and the direct in vivo angiogenesis assay, where angioreactors were implanted in CD1 female mice, showed that affinin and the HLEE increased vascular growth in a dose-dependent manner in both bioassays. This is the first study showing the proangiogenic effect of H. longipes. Further studies should focus on the mechanism of action and its possible therapeutic use in diseases characterized by insufficient angiogenesis.

Hypoxia Increases Nitric Oxide-Dependent Inhibition of Angiogenic Growth

Nitric oxide (NO) is a proangiogenic factor acting through the soluble guanylate cyclase (sGC) pathway. However, angiogenic growth increases energy demand, which may be hampered by NO inhibition of cytochrome c oxidase (CcO). Then, NO activity would be the balanced result of sGC activation (pro-angiogenic) and CcO inhibition (anti-angiogenic). NO activity in a rat and eNOS−/− mice aortic ring angiogenic model and in a tube formation assay (human aortic endothelial cells) were analyzed in parallel with mitochondrial O2 consumption. Studies were performed with NO donor (DETA-NO), sGC inhibitor (ODQ), and NOS or nNOS inhibitors (L-NAME or SMTC, respectively). Experiments were performed under different O2 concentrations (0–21%). Key findings were: (i) eNOS-derived NO inhibits angiogenic growth by a mechanism independent on sGC pathway and related to inhibition of mitochondrial O2 consumption; (ii) NO inhibition of the angiogenic growth is more evident in hypoxic vessels; (iii) in the absence of eNOS-derived NO, the modulation of angiogenic growth, related to hypoxia, disappears. Therefore, NO, but not lower O2 levels, decreases the angiogenic response in hypoxia through competitive inhibition of CcO. This anti-angiogenic activity could be a promising target to impair pathological angiogenesis in hypoxic conditions, as it occurs in tumors or ischemic diseases.

Emergent role of SARAF and store-operated Ca2+ entry in angiogenesis

Angiogenesis is a multistep process that controls endothelial cell (EC) functioning to form new blood vessels from preexisting vascular beds. This process is tightly regulated by pro-angiogenic factors, such as vascular endothelial growth factor (VEGF), which promotes signaling pathways involving the increase in the intracellular Ca2+ concentration ([Ca2+]i). Recent evidence suggests that store-operated Ca2+ entry (SOCE) might play a role in angiogenesis. However, little is known regarding the role of SARAF, SOCE-associated regulatory factor in this process. The aim of this study is to examine the role of SARAF in angiogenesis. In vitro angiogenesis was studied using human umbilical endothelial cells (HUVECs) for tube formation assay and vessel sprouting using rat aortic ring by Matrigel assay supplemented with endothelial cell basal medium enriched with different growth factors (VEGF, FGF, b-EGF, and IGF). HUVECs migration was evaluated by wound healing assay, and HUVECs proliferation using Ki67+ marker. Ex vivo angiogenesis was examined by whole mount mice retina on P6 in neonatal mice injected with increasing concentrations of a SOCE inhibitor, GSK-7975A, on P3, P4, and P5. We observed that SOCE inhibition with GSK-7975A blocks aorta sprouting, as well as HUVEC tube formation and migration. The intraperitoneal injection of GSK-7975A also delays the development of retinal vasculature assessed at postnatal day 6 in mice since it reduces vessel length and the number of junctions while it increases lacunarity. Moreover, we found that knockdown of SARAF using siRNA impairs VEGF-mediated [Ca2+]i increase and HUVEC tube formation, proliferation, and migration. Our data show for the first that SOCE inhibition prevents angiogenesis using different approaches and we provide evidence indicating that SARAF plays a critical role in angiogenesis.

Angiogenesis is Inhibited by Arsenic Trioxide Through Downregulation of the CircHIPK3/miR-149-5p/FOXO1/VEGF Functional Module in Rheumatoid Arthritis

Angiogenesis is a crucial event in the pathogenesis of rheumatoid arthritis (RA). Arsenic trioxide (ATO, As2O3) has been reported to inhibit synovial angiogenesis via the vascular endothelial growth factor (VEGF)-centered functional module. However, the exact mechanisms of ATO on VEGF modulation remain unclear. Circular RNAs (circRNAs) are emerging as important regulators in RA, and the detailed mechanisms remain largely unknown. Here, we reported a circRNA (circHIPK3), the expression of which was significantly increased in RA fibroblast-like synoviocytes (RA-FLS) after TNF-α induction. Moreover, VEGF content in the supernatants of a RA-FLS and human dermal microvascular endothelial cell (HDMEC) co-culture as well as in RA-FLS co-cultured was significantly elevated in accordance with circHIPK3 levels. This increased VEGF expression may significantly upregulate endothelial tube formation and transwell migration, as well as microvessel sprouting in the ex vivo aortic ring assay. CircHIPK3 was further illustrated to be a sponge for the forkhead box transcription factor O1 (FOXO1)-targeting miR-149-5p, leading to the changing expression of the downstream VEGF. These networked factors mainly form a functional module regulating angiogenesis in RA-FLS, and the expression of this functional module could be significantly downregulated by ATO with a consistently reduced vascularity in vitro. In the collagen-induced arthritis (CIA) mice model, an intra-articular injection of the adeno-associated virus-si-circHIPK3 or ATO was demonstrated to alleviate the synovial VEGF expression and arthritis severity respectively. Thus, we elucidate a previously unknown mechanism between circRNAs and RA, and ATO has a significant protective effect on RA-FLS and CIA synovium via its inhibition of the angiogenic functional module of circHIPK3/miR-149-5p/FOXO1/VEGF, suggesting great potential for the combination therapy of ATO with circHIPK3 silencing.

Annexin A2 Promotes Angiogenesis After Ischemic Stroke Via Annexin A2 Receptor - AKT/ERK Pathways

Promoting angiogenesis to restore circulation to the ischemic tissue is still an important therapeutic target in stroke. Here, we ask whether the Ca2+-regulated, phospholipid-and membrane-binding protein-Annexin A2 (ANXA2) may regulate angiogenesis after stroke.Compared with wild type (WT) mice, the density of microvessels in brain and the number of new vessels sprouting from aortic ring were significantly increased in Anxa2 knock-in (ANXA2+/+) mice. After focal cerebral ischemia, proliferation of brain endothelial cells in ANXA2+/+ mice was significantly elevated at 7 days post-stroke, which further improved behavioral recovery. To assess the pro-angiogenic mechanisms of ANXA2, we used brain endothelial cells cultures to investigate its effects on cell tube-formation and migration. Recombinant ANXA2 increased tube-formation and migration of brain endothelial cells either under normal condition or after OGD injury. These protective effects of recombinant ANXA2 were regulated by interaction with ANXA2 receptor (A2R), and the ability of ANXA2-A2R to activate AKT/ERK pathways. Taken together, our study indicates that ANXA2 might be involved in angiogenesis after ischemic stroke. Further investigation of ANXA2-A2R will provide a new therapeutic target for stroke.

Cyclic GMP-Dependent Regulation of Vascular Tone and Blood Pressure Involves Cysteine-Rich LIM-Only Protein 4 (CRP4)

The cysteine-rich LIM-only protein 4 (CRP4), a LIM-domain and zinc finger containing adapter protein, has been implicated as a downstream effector of the second messenger 3′,5′-cyclic guanosine monophosphate (cGMP) pathway in multiple cell types, including vascular smooth muscle cells (VSMCs). VSMCs and nitric oxide (NO)-induced cGMP signaling through cGMP-dependent protein kinase type I (cGKI) play fundamental roles in the physiological regulation of vascular tone and arterial blood pressure (BP). However, it remains unclear whether the vasorelaxant actions attributed to the NO/cGMP axis require CRP4. This study uses mice with a targeted deletion of the CRP4 gene (CRP4 KO) to elucidate whether cGMP-elevating agents, which are well known for their vasorelaxant properties, affect vessel tone, and thus, BP through CRP4. Cinaciguat, a NO- and heme-independent activator of the NO-sensitive (soluble) guanylyl cyclase (NO-GC) and NO-releasing agents, relaxed both CRP4-proficient and -deficient aortic ring segments pre-contracted with prostaglandin F2α. However, the magnitude of relaxation was slightly, but significantly, increased in vessels lacking CRP4. Accordingly, CRP4 KO mice presented with hypotonia at baseline, as well as a greater drop in systolic BP in response to the acute administration of cinaciguat, sodium nitroprusside, and carbachol. Mechanistically, loss of CRP4 in VSMCs reduced the Ca2+-sensitivity of the contractile apparatus, possibly involving regulatory proteins, such as myosin phosphatase targeting subunit 1 (MYPT1) and the regulatory light chain of myosin (RLC). In conclusion, the present findings confirm that the adapter protein CRP4 interacts with the NO-GC/cGMP/cGKI pathway in the vasculature. CRP4 seems to be part of a negative feedback loop that eventually fine-tunes the NO-GC/cGMP axis in VSMCs to increase myofilament Ca2+ desensitization and thereby the maximal vasorelaxant effects attained by (selected) cGMP-elevating agents.

Interleukin-17A Triggers the Release of Platelet-Derived Factors Driving Vascular Endothelial Cells toward a Pro-Angiogenic State

Platelets comprise a highly interactive immune cell subset of the circulatory system traditionally known for their unique haemostatic properties. Although platelets are considered as a vault of growth factors, cytokines and chemokines with pivotal role in vascular regeneration and angiogenesis, the exact mechanisms by which they influence vascular endothelial cells (ECs) function remain underappreciated. In the present study, we examined the role of human IL-17A/IL-17RA axis in platelet-mediated pro-angiogenic responses. We reveal that IL-17A receptor (IL-17RA) mRNA is present in platelets transcriptome and a profound increase is documented on the surface of activated platelets. By quantifying the protein levels of several factors, involved in angiogenesis, we identified that IL-17A/IL17RA axis selectively induces the release of vascular endothelial growth factor, interleukin -2 and -4, as well as monocyte chemoattractant protein -1 from treated platelets. However, IL-17A exerted no effect on the release of IL-10, an anti-inflammatory factor with potentially anti-angiogenic properties, from platelets. Treatment of human endothelial cell two-dimensional tubule networks or three-dimensional spheroid and mouse aortic ring structures with IL-17A-induced platelet releasate evoked pro-angiogenic responses of ECs. Our findings suggest that IL-17A may critically affect platelet release of pro-angiogenic factors driving ECs towards a pro-angiogenic state.