Microfluidic interactions between red blood cells and drug carriers by image analysis techniques

Blood is a complex biological fluid composed of deformable cells and platelets suspended in plasma, a protein-rich liquid. The peculiar nature of blood needs to be considered when designing a drug delivery strategy based on systemically administered carriers. Here, we report on an in vitro fluid dynamic investigation of the influence of the microcapillary flow of red blood cells (RBCs) on micron-sized carriers by high-speed imaging methods. The experiments were carried out in a 50 mu m diameter glass capillary that mimicked the hydrodynamic conditions of human microcirculation. Spherical mu-particles (mu-Ps), with sizes ranging between 0.5 and 3 mu m, were tested. Images of the flowing RBCs and mu-Ps were acquired by a high-speed/high-magnification microscopy. The transport and distribution of rigid particles in a suspension of RBCs under shear flow were investigated by analyzing: (i) the velocity profile of both mu-Ps and RBCs in the capillary; (ii) the radial distribution of mu-Ps in the presence of RBCs; (iii) the migration of mu-Ps towards the vessel wall due to their hydrodynamic interactions with RBCs. This study suggests that the therapeutic efficacy of mu-Ps could be ultimately affected by their interactions with the flowing RBCs in the vasculature. (C) 2016 IPEM. Published by Elsevier Ltd. All rights reserved.