Tracking Radiolabeled Endothelial Microvesicles Predicts Their Therapeutic Efficacy: A Proof-of-Concept Study in Peripheral Ischemia Mouse Model Using SPECT/CT Imaging

Microvesicles, so-called endothelial large extracellular vesicles (LEVs), are of great interest as biological markers and cell-free biotherapies in cardiovascular and oncologic diseases. However, their therapeutic perspectives remain limited due to the lack of reliable data regarding their systemic biodistribution after intravenous administration. Methods: Applied to a mouse model of peripheral ischemia, radiolabeled endothelial LEVs were tracked and their in vivo whole-body distribution was quantified by microSPECT/CT imaging. Hindlimb perfusion was followed by LASER Doppler and motility impairment function was evaluated up to day 28 post-ischemia. Results: Early and specific homing of LEVs to ischemic hind limbs was quantified on the day of ischemia and positively correlated with reperfusion intensity at a later stage on day 28 after ischemia, associated with an improved motility function. Conclusions: This concept is a major asset for investigating the biodistribution of LEVs issued from other cell types, including cancer, thus partly contributing to better knowledge and understanding of their fate after injection.

Analysis of cytokines in the aqueous humor during intravitreal Ranibizumab treatment of diabetic macular edema

This study aimed to analyze the concentrations of VEGF, b-FGF, TNF, interleukin (IL)-1, IL-6, IL-8, IL-10, and IL-12 in the aqueous humor of patients with diabetic macular edema with and without peripheral retinal ischemia and to ascertain the changes in the levels of these molecules during treatment with ranibizumab. A therapeutic, prospective, randomized interventional study was carried out. Twenty-four eyes from 24 patients were studied and divided into 3 groups. Group 1 (9 eyes) included patients with diabetic macular edema without peripheral ischemia. Group 2 (10 eyes) included patients with diabetic macular edema with peripheral ischemia. Group 3 (5 eyes), the control group, included patients without systemic and/or eye diseases. Patients in Groups 1 and 2 received 3 intravitreal injections of 2 mg/0.05 ml ranibizumab at an interval of approximately 30 days. Before administering the injections, the aqueous humor was collected. In the control group, aqueous humor was collected before facetectomy. During treatment, the median IL-6 concentration significantly increased in Group 1 but showed a slight but not significant decrease in Group 2. Interleukin 8 levels were significantly different at the end of treatment compared to the beginning in Groups 1 and 2. TNF, IL-1, IL-10, and IL-12 levels were practically unchanged in both groups. VEGF was significantly reduced at the end of the study in Groups 1 and 2. B-FGF was not detected in most of the studied patients, and in those with detectable levels, there was no significant variation. There was a significant increase in the median level of interleukin 6 in the group without ischemia and a significant decrease in VEGF in both groups. The cytokines TNF, IL-1, IL-10, and IL-12 did not show significant variation.

Fluocinolone Implant for Idiopathic Retinal Vasculitis, Aneurysms, and Neuroretinitis Syndrome: A Case Report

Idiopathic retinal vasculitis, aneurysms, and neuroretinitis (IRVAN) syndrome is a rare and progressive disorder that predominantly affects both the eyes of young female individuals and can threaten visual function. Peripheral ischemia and macular exudation are common findings in patients. The treatment options include panretinal photocoagulation (PRP), systemic immunosuppression, and intravitreal antiangiogenic and corticosteroid therapy. Fluocinolone acetonide intravitreal implant is approved for the treatment of nonanterior noninfectious uveitis and diabetic macular edema (ME), with an estimated therapeutic duration of 3 years. We describe a case of IRVAN syndrome in a child with ME who had been previously treated with PRP, antiangiogenic therapy, and several dexamethasone intravitreal implants and received a fluocinolone acetonide intravitreal implant in her right eye. The patient showed stabilization of the visual acuity and a marked reduction of the macular thickness 1 month after the treatment. At 12-month follow-up, the patient required perifoveal focal photocoagulation due to a rebound of the ME. After 2 years of follow-up, visual acuity remains stable and macular retinal thickening under control. Local long-standing steroid therapy has proved to be quite efficient in controlling the progression of the disease in our patient.

Extended-Duration Low-intensity Apixaban to Prevent Recurrence in Patients with Provoked Venous Thromboembolism: Design of the HI-PRO Trial

Patients with acute venous thromboembolism (VTE) in the setting of transient provoking factors are typically treated with short-term anticoagulation. However, the risk of recurrence may be increased in the presence of enduring risk factors. In such patients, the optimal duration of treatment remains uncertain. HI-PRO is a single-center, double-blind randomized trial. Patients with deep vein thrombosis (DVT) or pulmonary embolism (PE) following a major provoking factor, including major surgery or major trauma, who completed at least 3 months of standard-dose therapeutic anticoagulation and have at least one enduring risk factor (such as obesity or heart failure), will be considered for inclusion. Patients will be randomized to apixaban 2.5 mg twice daily or placebo for 12 months. The primary efficacy outcome will be symptomatic recurrent VTE –a composite of DVT and/or PE at 12 months after randomization. Secondary efficacy outcomes include a composite of death due to cardiovascular causes, nonfatal myocardial infarction, stroke or systemic embolism, major adverse limb events, or coronary or peripheral ischemia requiring revascularization at 12 months, and individual components of these outcomes. The primary safety outcome is major bleeding according to the International Society on Thrombosis and Haemostasis definition. The study plans to enroll 600 patients (300 per arm) to have 80% power for detecting a 75% relative risk reduction in the primary outcome. Active recruitment began in March 2021. HI-PRO will provide clinically meaningful data on whether patients with provoked VTE and enduring risk factors have fewer adverse clinical outcomes if prescribed low-intensity extended duration anticoagulation.

Analysis of Cytokines in the Aqueous Humor During Intravitreal Treatment With Ranibizumab in Diabetic Macular Edema

Purpose: This study aimed to analyze the concentrations, in aqueous humor, of VEGF, b-FGF, TNF, and interleukins 1, 6, 8, 10, and 12 in patients with diabetic macular edema, with and without peripheral retinal ischemia, and to analyze the variation of the levels of these molecules, during the treatment with ranibizumab.Methods: A therapeutic, prospective, randomized interventional study was carried out. Twenty-four eyes from 24 patients were studied, divided into 3 groups. Group 1, (9 eyes), patients with EMD without peripheral ischemia. Group 2 (10 eyes), patients with EMD with peripheral ischemia. Group 3, (5 eyes), control group, formed by patients without systemic and/or eye diseases. Patients in groups 1 and 2 were treated with 3 intravitreal injections of 2 mg/0.05 ml of ranibizumab, with intervals of approximately 30 days. Before performing the injections, the aqueous humor was collected. In the control group, the material was collected before the facectomy procedure. Results: During treatment, the medians of IL-6 concentrations showed a statistically significant increase, in group 1 and group 2, there was a slight decrease, not statistically significant. Interleukin 8 showed statistically significant variations in groups 1 and 2, at the end of treatment. TNF, IL-1, IL-10, and IL-12 had their concentrations practically unchanged, in both groups. VEGF showed a statistically significant reduction in groups 1 and 2 at the end of the study. B-FGF was not detected in most of the studied patients, and in those that were found, they did not present statistically significant numbers. Conclusion: There were statistically significant variations in the increase of their median levels in interleukin 6, in the group without ischemia and a decrease in VEGF in both groups. The cytokines TNF, IL-1, IL-10, and IL-12 did not show statistically significant variations.

Endothelial Aryl Hydrocarbon Receptor Nuclear Translocator Mediates the Angiogenic Response to Peripheral Ischemia in Mice With Type 2 Diabetes Mellitus

Hypoxia-inducible factors (HIFs) are the master regulators of angiogenesis, a process that is impaired in patients with diabetes mellitus (DM). The transcription factor aryl hydrocarbon receptor nuclear translocator (ARNT, also known as HIF1β) has been implicated in the development and progression of diabetes. Angiogenesis is driven primarily by endothelial cells (ECs), but both global and EC-specific loss of ARNT-cause are associated with embryonic lethality. Thus, we conducted experiments in a line of mice carrying an inducible, EC-specific ARNT-knockout mutation (ArntΔEC, ERT2) to determine whether aberrations in ARNT expression might contribute to the vascular deficiencies associated with diabetes. Mice were first fed with a high-fat diet to induce diabetes. ArntΔEC, ERT2 mice were then adminstrated with oral tamoxifen to disrupt Arnt and peripheral angiogenesis was evaluated by using laser-Doppler perfusion imaging to monitor blood flow after hindlimb ischemia. The ArntΔEC, ERT2 mice had impaired blood flow recovery under both non-diabetic and diabetic conditions, but the degree of impairment was greater in diabetic animals. In addition, siRNA-mediated knockdown of ARNT activity reduced measurements of tube formation, and cell viability in human umbilical vein endothelial cells (HUVECs) cultured under high-glucose conditions. The ArntΔEC, ERT2 mutation also reduced measures of cell viability, while increasing the production of reactive oxygen species (ROS) in microvascular endothelial cells (MVECs) isolated from mouse skeletal muscle, and the viability of ArntΔEC, ERT2 MVECs under high-glucose concentrations increased when the cells were treated with an ROS inhibitor. Collectively, these observations suggest that declines in endothelial ARNT expression contribute to the suppressed angiogenic phenotype in diabetic mice, and that the cytoprotective effect of ARNT expression in ECs is at least partially mediated by declines in ROS production.

Succinate Injection Rescues Vasculature and Improves Functional Recovery Following Acute Peripheral Ischemia in Rodents: A Multimodal Imaging Study

Succinate influences angiogenesis and neovascularization via a hormonelike effect on G-protein-coupled receptor 91 (GPR91). This effect has been demonstrated in the pathophysiology of diabetic retinopathy and rheumatoid arthritis. To evaluate whether succinate can play a role in acute peripheral ischemia, a preclinical study was conducted with ischemic mice treated with succinate or PBS and evaluated by imaging. Acute ischemia was followed by an increased in GPR91 expression in the ischemic muscle. As assessed with LASER-Doppler, succinate treatment resulted in an earlier and more intense reperfusion of the ischemic hindlimb compared to the control group (* p = 0.0189). A microPET study using a radiolabeled integrin ligand ([68Ga]Ga-RGD2) showed an earlier angiogenic activation in the succinate arm compared to control mice (* p = 0.020) with a prolonged effect. Additionally, clinical recovery following ischemia was better in the succinate group. In conclusion, succinate injection promotes earlier angiogenesis after ischemia, resulting in a more effective revascularization and subsequently a better functional recovery.