Size-dependent interactions between calciprotein particles and vascular endothelium.

The underlying mechanisms governing the interactions between nanoparticles and vascular endothelial barrier remain largely unexplored, which is crucial for the optimal design of nanoparticles for clinical applications. In this study, the size-dependent interactions between calciprotein particles (CPPs) and endothelial cells (ECs) were investigated using a rat model of chronic kidney disease (CKD) induced by 5/6 nephrectomy. Two primary types of CPP1 were studied: small-sized CPP1 (S-CPP1, <50 nm) and larger CPP1 (L-CPP1, <100 nm), detected three and five weeks post-surgery, respectively. By adjusting the amounts of Ca, HPO and HPO ions in Dulbecco's Modified Eagle Medium supplemented with 10 % (V/V) fetal bovine serum and 1 % (V/V) Pen-Strep solution, S-CPP1 (<50 nm) with an elliptical shape, L-CPP1 (50-100 nm), and secondary CPPs (CPP2, >100 nm) with a needle-like crystalline structure, resembling endogenous CPPs, were synthesized. The results showed that S-CPP1 significantly increased endothelial permeability at concentrations of 445 μg/mL and 890 μg/mL, thereby disrupting the integrity of the endothelial barrier formed by a confluent monolayer of ECs. Immunofluorescence analysis revealed that L-CPP1 was internalized by ECs via endocytosis, while S-CPP1 disrupted VE-cadherin junctions, leading to irregular cell morphology and widened intercellular gaps. These structural changes likely contribute to medial calcification as CPPs accumulate within the circulatory system. In conclusion, the findings underscore that the interaction between CPPs and the vascular endothelium is strongly size-dependent, with significant implications for vascular system health and the design of nanoparticle-based therapies.