Protein nanoparticles: cellular uptake, intracellular distribution, biodegradation and induction of cytokine gene expression.

Intracellular delivery of protein nanoparticles (NP) is required for nanomedicine. Our research was focused on the quantitative analysis of protein NP intracellular accumulation and biodegradation in dynamics along with host cytokine gene expression. Fluorescent NP fabricated by nanoprecipitation without cross-linking of bovine serum albumin (BSA) and human immunoglobulins (hIgG) pre-labeled with Rhodamine B were non-toxic for human cells. Similar gradual uptake of the NP during 2 days and subsequent slowdown until background values for 5 days for human cell lines and donor blood mononuclear cells revealed that NP internalization was neither cell-type nor protein-specific. NP delivery into cells was inhibited by homologous and heterologous NP but did not depend on the presence of BSA or hIgG in culture media. The protein NP internalization induced interferon α, β, λ but neither γ nor interleukin 4 and 6 gene expression. Accordingly, cellular uptake of non-toxic protein NP induced Th1 polarized innate response.