Harnessing human blood to examine bio-nano interactions at the cellular level

Aim: The capacity to predict interactions between nanomaterials and primary human cells will benefit the rational design of novel nano medicines. However, these fundamental relationships have not been adequately defined. By... [ view full abstract ]

Aim: The capacity to predict interactions between nanomaterials and primary human cells will benefit the rational design of novel nano medicines. However, these fundamental relationships have not been adequately defined. By examining various nanoparticle systems with fresh human blood cells, we aim to establish principles of bio-nano interactions and generate predictive relationships that can inform the next generation of nanomedicines.

Methods: Four separate nanoparticle technologies were used to generate particles with varying charge and surface chemistries. Each particle was incubated with fresh healthy human blood (to study cell association/uptake) or purified cells (to study immune activation) at 37˚C and 4˚C and analysed by flow cytometry.

Results: The properties of nanoparticles significantly impact immunological outcomes, including immunoactivation and leukocyte uptake.
a. Hyperbranched polymers (HBPs) differentially activate primary human blood dendritic cells based on charge. HBP of 8 nm diameter were prepared and tested under endotoxin-free conditions. Cationic (+16 mV) HBPs activated myeloid dendritic cells (DC; 51.7 ± 4.3% IL-8+) but not plasmacytoid DCs, while neutral and anionic (-15 mV) HBPs were not immunostimulatory to either subset.
b. Charge dictates HBP association with different immune cell subsets. Cationic HBPs associated with most cell types (monocytes, granulocytes, DCs and B cells), while at 37˚C anionic HBPs preferentially associated with cells specialized for pathogen clearance and processing.
c. Nanoparticles engineered with terminal disulphides displayed enhanced association with human blood components, particularly phagocytic cells and platelets, over control nanoparticles.
d. Altering the chemical composition of nanoparticle surfaces can reduce phagocytic clearance. Linear poly(ethylene)glycol surfaces reduced phagocytic uptake compared with brushed poly(ethylene)glycol of the same molecular weight.

Conclusion/Future: We are in the process of creating a nanoparticle ‘characteristic matrix’ to examine the effect of single nanoparticle characteristics on immunoactivation and blood interaction profiles. We will subsequently apply mathematical modelling principles to generate predictive models of bio-nano interactions.