Stability and bioactivity of chitosan as a transfection agent in primary human cell cultures: A case for chitosan-only controls.

•Chitosan microparticle size is augmented by incubation under cell culture conditions.•Chitosan polymers modulate viability in cells exposed to acidotic conditions.•Transfection with chitosan particles enhances CD59 mRNA but not surface expression.•Chitosan polymers directly alter CD59 surface expression in primary human cells.