Long Circulating Nanoparticles as Potential Antigen Carriers in Angiogenic Blood Vessels: Towards Tolerogenesis

Infants do not produce typical immune responses to foreign ABO-blood group antigens compared to older individuals who have a fully developed immune system. Therefore, incompatible donor organs can be transplanted into infants without rejection, which results in immunological tolerance. As a result, we hypothesized that intentional introduction of ABO-antigens would also induce tolerance and extend the period of time for safe ABO- incompatible transplantations. A proposed method to induce tolerance is by conjugating antigens to long-circulating silica nanoparticles and injecting them into blood vessels to promote maximum exposure of lymphocytes to the antigens. Here, we characterized synthesized nanoparticles for this purpose. Nanoparticle brightness and aggregation tendencies were determined for detectability and stability in a living system, respectively, using fluorescence correlation spectroscopy. Bright, non-aggregating nanoparticles were injected into the chorioallantoic membrane of chicken embryos to monitor circulation. It was determined that 100 - 200nm PEG-coated silica nanoparticles were easily detected, aggregated little, and circulated for a prolonged period of time in the blood stream.