A detailed comparison of different types of ceramic nanoparticles has found that those made of silica can efficiently transport therapeutic genes to the spleen and trigger a potent immune response capable of attacking tumors.
This work, led by Kam Hui, Ph.D., of the National Cancer Centre in Singapore, appears in the journal Gene Therapy.
Working with ceramic nanoparticles made of silica, hydroxyapatite (the mineral that makes up bone), and zirconia, the investigators studied the effect of charge and surface coating on the efficiency with which these nanoparticles could deliver DNA to the nucleus of cells. These experiments revealed that silica particles coated with protamine sulfate, a naturally occurring, positively charged protein used to treat anticoagulant overdoses, had the best combination of physical characteristics to function as gene delivery vehicles.
After optimizing the protamine-coated silica nanoparticles for DNA delivery to cells, the investigators loaded the particles with a gene that codes for the firefly protein luciferase. Within 24 hours after injecting these particles into mice, the researchers found high levels of gene expression in the spleens of the treated mice, with little gene expression occurring in the liver or kidneys. Microscopy studies showed that only the spleen accumulated measurable levels of the injected nanoparticles, suggesting to the researchers that they had developed a spleen-specific gene delivery system.