PEI – a potent, but not harmless, mucosal immuno-stimulator of mixed T-helper cell response and FasL-mediated cell death in mice

Gene Expression Profiles in Mouse Lung Tissue after Administration of Two Cationic Polymers Used for Nonviral Gene Delivery

“…Earlier studies have shown that chitosan has immunostimulatory properties and it has therefore been used as a nasal adjuvant for protein antigen formulations in humans (9). In a recent study, we found that PEI can also stimulate the immune system (10) and, in an attempt to obtain more detailed information about how these polymers affect relevant tissues, we undertook this study on the local tissue effect after pulmonary delivery of the formulations to mice.…”

Improved chitosan-mediated gene delivery based on easily dissociated chitosan polyplexes of highly defined chitosan oligomers

“…5 These polymers are synthetic and not biocompatible and a rough correlation between toxicity and efficiency has been suggested for PEI. 6 In particular, several recent studies have addressed concerns about the toxicity of conventional PEI, [7][8][9] although PEIs of decreased molecular weights and degree of branching seem to have a reduced toxicity. 10,11 Therefore, the search for alternative biocompatible cationic polymers that form efficient and nontoxic polyplexes is motivated.…”

Liposome-based polymer complex as a novel adjuvant: enhancement of specific antibody production and isotype switch

“…PEI activates Th1 and Th2 gene expression in murine splenocytes. 35 Although only a few PEI molecules are incorporated into LPPC (1 µg/100 µg LPPC), they contribute to the positive charge on the surface zeta potential of LPPC. 20 As a cationic liposome, the positive charge of PEI aids particle uptake by the electronic interaction between LPPC and APCs.…”