In vitro behaviour of hybrid lipid/chitosan nanoparticles for the oral delivery of heparin

Enhanced oral bioavailability of poorly aqueous soluble drugs encapsulated in a number of lipid-based formulations, including emulsions, micellar systems, self-emulsifying drug delivery systems, liposomes and solid lipid nanoparticles (SLN) via lymphatic delivery has been documented. In the present work, SLN were designed for the oral delivery of heparin in order to take advantage from the lymphatic intestinal transport pathway. In order to improve the incorporation of a high hydrophilic compound in a lipid matrix, heparin was “insolubilized” by the coupling with chitosan. In this aim we have developed chitosan/heparin Polyelectrolyte complexes (PEC). Such as systems are able to complex stably heparin (up to pH < 6.8) (Paliwal R. et al. 2012) and after pelletization by centrifugation were embedded in SLN obtaining a hybrid system lipid/chitosan nanoparticles (PEC-SLN). Since no in-vitro lymphoid tissue is currently available, CaCo-2 cell monolayer could be considered an alternative in vitro model to be used as a screening tool before animal studies are undertaken. In this work naked PEC, hybrid PEC-SLN as well as heparin-loaded SLN (Hep-SLN) were characterized as regard as the size, Z-potential, morphology, drug loading and in vitro drug release. Moreover, FITC labeled PEC along with Red Nile labeled PEC-SLN and empty SLN were evaluated on CaCo-2 cell line in order to study their cytotoxicity by MTT test and their cell internalization ability by cytometric and confocal analysis. Finally, transepithelial electrical resistance (TEER) was measured on NCM460 cells in order to evaluate the integrity of the tight junctions.