Modification of primary amines to higher order amines reduces in vivo hematological and immunotoxicity of cationic nanocarriers through TLR4 and complement pathways

Randall Toy; Pallab Pradhan; Vijayeetha Ramesh; Nelson C. Di Paolo; Blake Lash; Jiaying Liu; Emmeline L. Blanchard; Philip J. Santangelo; Dmitry M. Shayakhmetov; Krishnendu Roy

The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. . https://doi.org/10.1101/647305 doi: bioRxiv preprint CONCLUSIONS Taken together, our findings illustrate that in vivo systemic toxicity is regulated by a combination of different biological phenomena -TLR activation, complement activation, liver toxicity, and changes in hematology. The contributions of each biological phenomenon to cationic nanomaterial toxicity is different for different materials -for bPEI, toxicity profile is driven by liver toxicity and changes in hematology; while for chitosan, the toxicity profile is governed by a balance of TLR and complement activation. The classification of what makes a "safe nanoparticle" must be determined by a weighted consideration of each of these in vivo biological phenomena. We also conclude that chemical modifications do not affect toxicity in the same manner when applied to different polymers. Our results also show that in vitro measures of the innate immune response, as with the example of IAA-modified chitosan, do not accurately predict in vivo toxicity. Therefore, it is essential to move beyond in vitro cytotoxicity screens for nanomaterials to more informative, and detailed in vivo toxicity tests to appropriately select nanoparticle candidates for clinical nucleic acid delivery.