Abstract
Anionic liposomal formulations have previously shown to have intrinsic tolerogenic capacity and these properties have been related to the rigidity of the particles. The combination of highly rigid anionic liposomes to deliver tolerogenic adjuvants and antigen peptides has potential applications for the treatment of autoimmune and inflammatory diseases. However, the preparation of these highly rigid anionic liposomes using traditional methods such as lipid film hydration presents problems in terms of scalability and loading efficiency of some costly tolerogenic adjuvants like 1-α,25-dihydroxyvitaminD3. Here we propose the use of an off-the-shelf staggered herringbone micromixer for the preparation of these formulations and performed a systematic study on the effect of temperature and flow conditions on the size and polydispersity index of the formulations. Furthermore, we show that the system allows for the encapsulation of a wide variety of peptides and significantly higher loading efficiency of 1-α,25-dihydroxyvitaminD3 compared to the traditional lipid film hydration method, without compromising their non-inflammatory interaction with dendritic cells. Therefore, the microfluidics method presented here is a valuable tool for the preparation of highly rigid tolerogenic liposomes in a fast, size-tuneable and scalable manner.
Highlights
Liposomes are nanometer size vesicles formed by a lipid bilayer enclosing an aqueous core and are used for various applications, including vaccination
Temperature of the system is a key parameter for the preparation of monodisperse highly rigid anionic liposomes by microfluidics
In previous studies we have shown that highly rigid anionic liposomal formulations containing distearoyl-sn-glycero-3-phosphoglycerol (DSPG) are more efficient at delivering their cargo and inducing T regulatory cells[3]
Summary
Liposomes are nanometer size vesicles formed by a lipid bilayer enclosing an aqueous core and are used for various applications, including vaccination. The physicochemical properties of liposomal formulations can influence their capacity to induce tolerogenic immune response, the generation of a strong tolerogenic response might require the inclusion of tolerogenic adjuvants Immune modulatory molecules such as 1-α,25dihydroxyvitaminD3 (VD3), rapamycin or retinoic acid have been widely studied for their capacity to induce tolerogenic dendritic cells and may provide interesting adjuvants for tolerogenic vaccines[4,5,6]. Despite their high hydrophobicity index, the loading efficiency of these molecules, specially VD3, into highly rigid anionic liposomes using the traditional lipid film hydration method is surprisingly low (Table 1) with only a small fraction (
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