EVALUATION OF STABILITY AND INTERNALIZATION BY EUCARIOTIC CELLS OF POLYMER LIPIDS COMPLEXES FORMED BY LACTIC ACID BACTERIAL LIPIDS

SZYMANOWSKI F.; HUGO A.A; PÉREZ P.F.

Tucuman

Simposio; V Simposio Internacional de Bacterias Lácticas.; 2016

CERELA

Liposomes areattractive vehicles for drug delivery and their lipid composition is crucialfor the stabilization of liposome formulations. Bacterial lipids are mainlyfound in cell membranes and play a main role in stabilizing the membranestructure when cells are exposed to stress. Lipids from lactic acid bacteria (LAB)represent natural formulations that may be potentially useful in drug delivery.The internalization of liposomes by target cells can be favored by theincorporation of pH-sensitive polymers, such as Poly (2-(dimethylamino) ethylmethacrylate) (PDMAEMA). The aim of this work was the study of the mechanismsof cellular uptake of liposomes formed by lipids of Lactobacillus delbrueckii subsp. lactis CIDCA 133 and their serum stability in vitro. Fluorescentliposomes were prepared by reverse-phase evaporation. The dried lipid film wasrehydrated with calcein or carboxifluorescein (CF) buffer. To form polymerlipid complexes (PLCs), cholesterol PDMAEMA (CHO-PDMAEMA) was added. Lecithin(LC) liposomes were used as controls. Stability of liposomes was evaluated by releaseof entrapped CF in the presence of different concentrations of normal fetalbovine serum (FBS). Liposome uptake by eukaryotic cells (HEK 293 andCaco-2/TC7) was evaluated by flow cytometry in the presence of endocytosisinhibitors. Intracellular localization of liposomes was assessed by confocalmicroscopy. CHO-PDMAEMA containing liposomesshowed higher cargo capacity and were more internalized by eukaryotic cellsthan bare liposomes. Bacterial liposomes were more stable than lecithin (LC) liposomesat all the serum concentrations assayed. Bacterial and LC liposomes suffered anoticeable decrease of internalization by cells at 4°C. The uptake of liposomesshowed a significantly decrease with caveolae inhibitors whereas it was similarto control with clarthrin and macropinocytosis inhibitors. Confocal images correlatedwith those results showing colocalization between liposomes and albumin whichis a marker of caveolae pathway. Liposomes did not colocalize with lysotrackerindicating that they did not route to lysosomes. The main problems associated to drugdelivery systems are the degradation in the bloodstream and/or theintracellular destruction of liposome cargo. In this work we demonstrated thatPLCs formed by LAB lipids are very stable in the presence of serum and thatthey internalize through the caveolae endocytic pathway (a non-degradativepathway). Our results support the potential use of LAB lipids in liposome drugdelivery systems.