Vitamin B12-mediated transport of nanoparticles across Caco-2 cells

Several studies have shown that Caco-2 cells have the capability to transport peptides and proteins from their apical to basal surfaces when these molecules are linked to vitamin B-12 (VB12). In this study we have extended these studies and have shown that Caco-2 cells are also able to internalize and transport VB12-modifed nanoparticles from their apical to basal surfaces. Uptake and transport of nanoparticles was found to occur in both a VB12-dependent intrinsic factor (IF)-independent manner as well as in a VB12-dependent IF-dependent manner. Both IF-independent and IF-dependent VB12-mediated uptake and transport were dependent upon the surface density of VB12 as a reduction in surface modification of the nanoparticles with VB,, resulted in a reduced level of both VB12-mediated and IF-mediated uptake. At lower levels of VB,, modification there was no apparent non-IF-mediated uptake; however, VB12-IF-mediated uptake was still measurable. These studies show that Caco-2 cell cultures are a suitable model for the study of VB12-mediated uptake and transport of nanoparticles, and suggest that for effective oral uptake of VB12-coated nanoparticles high surface densities of VB12 are required. (C) 1999 Elsevier Science B.V. All rights reserved.