The mounting interest in layered double hydroxide (LDH) nanoparticles as drug carriers and bio-imaging contrast agents makes biosafety evaluation of LDH essential. Considering the important role of blood circulation in bio-distribution of nanoparticles, the present work evaluated the impact of MgAl-LDHs on key components of the circulatory system, including vascular cells (vascular smooth muscle cells (SMCs) and endothelial cells (HUVECs)), red blood cells (RBCs), and complement activation. The results showed that LDH had no effects on SMCs and HUVECs at concentrations up to 500 and 10 mu g/mL respectively, in terms of cell proliferation and viability. LDH (10 mu g/mL) did not change either the migration distance or the number of migrating SMCs in culture. Moreover, LDH (400 mu g/mL) had a negligible effect on RBCs' lysis, and there was no significant increase in levels of complement activation product, C5a, in the presence of LDH (20 or 200 mu g/mL). The low toxicity for vascular cells and blood cells combined with low immunogenicity sheds a light on the biosafety of LDH nanoparticles, and encourages further studies into their biomedical applications. (C) 2017 Elsevier Inc. All rights reserved.