Radiotracer Imaging of Unstable Plaque
Robert J. Gropler, David K. Glover, Albert J. Sinusas, Heinrich Taegtmeyer in Cardiovascular Molecular Imaging, 2007
As an atherosclerotic lesion progresses from fatty streak to frank plaque apoptotic death of vascular smooth muscle cells increases as the neotimal lesion grows and the vessel remodels (19–21). In cell culture, plaque-derived vascular smooth muscle cells from human lesions undergo apoptosis at faster rate than nonatherosclerotic vessels (19). An early detectable change in cells undergoing programmed cell death is the externalization of phosphatidylserine (PS), a component of the cell membrane lipid bilayer (22). Normally PS is located on the inner bilayer but under internal signals the lipid components of the membrane are redistributed and PS moves from the inner to outer layer making it available for binding. Annexin V is an endogenous protein (35 kDa) that binds specifically to PS with very high affinity (22). Annexin V can be bound to 99mTc making it a probe that targets apoptosis. Because of the abundance of binding sites in tissue undergoing apoptosis and because of the commonality of programmed cell death to several prevalent diseases many experimental studies and clinical studies have been reported using 99mTc-annexin V to target apoptosis in cancer, myocardial infarction, and for vascular imaging (8,23–25).
The Etiology of the Antiphospholipid Syndrome
Howard J.A. Carp in Recurrent Pregnancy Loss, 2020
Furthermore, aPL may influence the placental circulation by attacking certain placental epitopes such as Annexin A5, a potent anticoagulant protein. Annexin V, found on the apical surface of placental syncytiotrophoblast, forms a protective shield on the phospholipid surface, blocking phospholipids from becoming available for coagulation reactions. The annexin-V shield could be damaged by either binding to anti-annexin-V or preventing its binding to the PL membrane, or by blocking autoantibodies against annexin-V/PL [36]. Anti-annexin-V autoantibodies have been detected in patients with systemic lupus erythematosus (SLE) and APS associated with pregnancy loss, while reduced levels of annexin-V have been observed on the placental villi of women with aPL, recurrent pregnancy loss, and a thrombogenic background [37].
Multimodality probes for cardiovascular imaging
Yi-Hwa Liu, Albert J. Sinusas in Hybrid Imaging in Cardiovascular Medicine, 2017
As with single-modality tracers, apoptosis can be investigated by targeting annexin signaling (Bauwens et al. 2011; Laufer et al. 2009; Wang et al. 2013). PEGylated micelles were engineered to include an iron oxide core or Gd-DTPA lipids, with additional fluorescent lipid markers incorporated into the lipid bilayer and further functionalized with Annexin A5-cys to target apoptosis. Superparamagnetic micelles exhibited increased relaxivity on transmission electron microscopy as defined by high r2/r1 ratio (as a negative contrast agent), with an average diameter of ~10 nm. Functionalized liposomes showed high calcium-dependent binding to phosphatidylserine in ellipsometry measurements (Andree et al. 1990). MR imaging of apoptotic Jurkat cell pellets displayed hypointesity on T2-weighted MR and hyperintensity on T1-weighted MR, with prolonged relaxation rates confirmed. Fluorescence imaging verified localization within the apoptotic cells (Figure 11.1) (van Tilborg et al. 2006). More extensive in vivo studies remain in progress.
Does LH supplementation in poor responders affect granulosa cells apoptosis rate in ART? A prospective randomised controlled trial
Published in Journal of Obstetrics and Gynaecology, 2022
Sebnem Alanya Tosun, Enis Ozkaya, Basak Aru, Gulderen Yanikkaya Demirel, Ebru Cogendez, Mehmet Sipahi
Flow cytometry is an actual technique used to detect GCs (about 5000 per follicle) and CD45 monoclonal antibody is useful to remove the white blood cell fraction to improve the accuracy of isolating them. During the apoptosis process, phosphatidylserine (PS) translocates from the inner side of the plasma membrane to the outer side and causes the asymmetric shape of the plasma membrane as an early event. Annexin V is a calcium-dependent phospholipid-binding protein that strongly interacts with PS (van Engeland et al. 1998). Additionally, co-staining with propidium iodide (PI) and analysing by flow cytometry, GCs are assessable as viable cells (annexin V− PI−), early apoptotic cells (annexinV+ PI−), late apoptotic cells (annexin V+ PI+) and necrotic cells (annexinV−PI+) (Fan et al. 2019). There was no significant effect of hyaluronidase treatment on cell viability and apoptosis rates.
Acriflavine-loaded solid lipid nanoparticles: preparation, physicochemical characterization, and anti-proliferative properties
Published in Pharmaceutical Development and Technology, 2021
Somayeh Vandghanooni, Forough Rasoulian, Masoud Eskandani, Sattar Akbari Nakhjavani, Morteza Eskandani
The treated A549 cells were stained with annexin V-FITC/PI and then a flow cytometry technique was performed to detect necrosis and apoptosis. Annexin V is a calcium/phospholipid-binding protein that has a high tendency to phosphatidylserine (Ptd-L-Ser). During apoptosis, phosphatidylserines turn from the inside of the cell wall to the outside of the cell membrane. These changes are the first differentiation of apoptotic cells which can be labeled with a fluorescent probe and detected (Van Heerde et al. 1995; Bossy-Wetzel and Green 2000; Esposito et al. 2005; Niu and Chen 2010). In this experiment, PI is also used, which can label the broken DNA at the final stages of apoptosis or necrosis. In our experiments, the incidence of apoptosis was confirmed in A549 cells which were treated with plain ACF and ACF-SLNs (Figure 6). The results showed that approximately 48% of the treated cells with plain ACF were in apoptosis, while less than 3% of the cells were in necrosis after 48 h. In the case of ACF-SLNs, as Figure 6 shows, ∼55% of the treated cells were in apoptosis and 5% of the cells were in necrosis after 48 h. The results showed that ACF-SLNs and the plain drug led to cell death, mainly by activating the apoptotic pathways.
Development of a PHBV nanoparticle as a peptide vehicle for NOD1 activation
Published in Drug Delivery, 2021
Mauricio Cabaña-Brunod, Pablo A. Herrera, Valeria Márquez-Miranda, Felipe M. Llancalahuen, Yorley Duarte, Danilo González-Nilo, Juan A. Fuentes, Cristián Vilos, Luis Velásquez, Carolina Otero
As different concentrations of PHBV NPs generate a discrete cytotoxic effect on RAW 264.7 cells. The next step was to determine whether these NPs could be triggering some apoptosis process. To this end, we evaluated the integrity of the cell membrane by annexin V, an apoptosis early marker. Annexin V preferentially binds to phospholipids that are translocated from the inside to the outside of the cell membrane in the early stages of apoptosis. Results obtained by flow cytometry indicate no significant changes in apoptosis levels concerning the negative control with only culture medium (except at a concentration of 1000 µg/ml) (Figure 6(A)). Furthermore, at a chosen concentration of 100 µg/ml, empty NPs do not show significant changes in apoptosis levels over time when measured at different times (1, 2, 4, 6, 24, and 48 h) (Figure 6(B)). As a positive control, a concentration of 1 µM H2O2 was used as an oxidizing agent capable of inducing apoptosis by over 50% in RAW 264.7 cells (Piao et al., 2011).