UC Riverside

Erythrocyte-derived platforms are garnering increasing attention as delivery vehicles due to their advantages in biocompatibility, low immunogenicity, tunable size and naturally long circulation. Erythrocyte carriers can be used to deliver various diagnostic and therapeutic cargos for clinical application such as tumor or vascular imaging. We have developed erythrocyte-derived optical particles loaded with the near-infrared (NIR) chromophore, such as FDA-approved indocyanine green (ICG). We refer to these constructs as NIR erythrocyte-derived transducers (NETs). They can generate heat, emit fluorescence, and mediate the production of reactive oxygen species(ROS) once being photoexcited by NIR light.We analyzed the proteomes of micro- and nano-sized erythrocyte-derived particles as compared to their native erythrocytes. Next, we demonstrated that enriching membrane cholesterol on NETs reduces phosphatidylserine (PS) exposure, which serves as a signal for phagocytic removal once PS externalized to outer leaflet of plasma membrane, and thus prolong their longevity in vivo to up to 24hr post-injection. Further, we investigated the effectiveness of enriching the membrane cholesterol content and folate-functionalizing of nano-sized NETs (nNETs) on biodistribution of these particles in organs and tumors of immunodeficient mice implanted with intraperitoneal ovarian cancer cells. Our results suggest that cholesterol enrichment of nNETs in combination with folate functionalization can result in greater accumulation of particles in tumors, providing a potential approach for enhanced NIR imaging of tumors. We also evaluated the capability of micro-sized NETs (μNETs) in mediating photothermal destruction of cutaneous vasculature in the rabbit earlobe as a model system for port wine stain (PWS). We successfully demonstrated that pulsed 755 nm laser irradiation at reduced radiant exposure in conjunction with administration of these μNETs results in a complete blood flow cessation in rabbit earlobe vasculature, indicating a potentially promising method to treat PWS. Finally, toward developing a novel carrier with dual-modality that can be used in both NIR and magnetic resonance (MR) imaging of tumors, we demonstrated the engineering and characterization of erythrocyte-derived particles that can be dually loaded with NIR brominated cyanine dye and gadobenate dimeglumine (Gd) agent.