Researchers of University of Sassari, Italy, have studied the effect of polymer coating in immune cells response. Pluronic (Pluro), chitosan (Chito), and polyethylene glycol-polylactic acid (PEG) were grafted around biodegradable lipid nanocapsules (NCs), made of olive oil in core and epikuron 145V in shell. First, it was noticed that PEGs and Pluro NCs were stable in physiological condition while Chito were not. In vitro studies demonstrated the uptake of the three polymer-coated NCs by different immune cells line (T cells, monocyte, lymphocytes T helper etc.). The PEG NCs had no cytotoxic effect in the different cell lines. However, pluro NCs were cytotoxic for monocyte, and Chito NCs were shown to be deleterious for monocyte and T cells. Incubation of the different NCs with human peripheral blood mononuclear cells (PBCMS) confirmed the stealthy behavior of PEG NCs (no immune activation and cytokine secretion). On the contrary, immune activation was observed with Pluro and Chito NCs along with cytokine secretion produced by monocyte for both systems, which is a marker of immune response. Specific Th2 cells cytokine secretion was produced after Chito NCs uptake, which would be characteristic of allergic response.
The paper confirms the safety and stealthy behavior of PEG coating. On the contrary, Pluro and Chito NCs induce an immune response and do not seem appropriate for in vivo application. Finally, aggregation observed for Chito NCs does not, in our point of view, conclude the allergic character of the polymer, as it was suggested.