Abstract 15017: Nanoanalytical Analysis of Bisphosphonate-Induced Alteration of Microcalcifications Using a 3D Hydrogel Platform
Vascular calcification predicts atherosclerotic plaque rupture and cardiovascular events. Retrospective studies of women taking bisphosphonates (BiP), a proposed therapy for vascular calcification, paradoxically increased risk in patients with prior acute events but decreased risk in other patients. We recently demonstrated that calcifying extracellular vesicles (EV) released by cells within the plaque aggregate and nucleate calcific mineral. We hypothesize that BiP block EV aggregation and modify existing mineral growth, potentially altering microcalcification morphology and the resultant risk of plaque rupture. 3D collagen hydrogels incubated with calcifying EV modeled fibrous cap calcification, serving as a platform to image mineral nucleation and test potential therapies for vascular calcification. This study visualized EV aggregation and formation of stress-inducing microcalcifications at single-EV resolution, via scanning electron microscopy. Finite element analysis (FEA) of a representative microcalcification formed in the 3D platform predicted a consequential 350% increase in fibrous cap tensile stress (Figure, red color). Energy-dispersive x-ray spectroscopy (EDS) confirmed that EV aggregates contained calcium and phosphorous. BiP (ibandronate) treatment added on day 0 decreased the size (21.5 μm2 vs. 14.2 μm2) and EDS-detected calcium (4.32% by weight (wt%) vs. 2.36 wt%) and phosphorous (4.26 wt% vs. 1.94 wt%) comprising EV aggregates measured on day 8. However, an increase in mineral was measured when BiP was added at later time points (Graph). BiP treatment altered microcalcification morphology in a time-dependent manner. These findings support our hypothesis that BiP alter EV-driven calcification, which may help explain confounding clinical data. The study confirmed that our 3D hydrogel is a viable platform to study EV-mediated mineral nucleation and evaluate potential therapies for cardiovascular calcification.
Author Disclosures: J.L. Ruiz: None. J.D. Hutcheson: None. L. Cardoso: None. T. Pham: None. S. Weinbaum: None. E. Aikawa: None.
- © 2016 by American Heart Association, Inc.