Smart Blood: Red Blood Cell based Drug Carriers

The era of one-disease-one-pill is long gone. We are now tackling complex diseases such as Alzheimer’s disease, cancer, and infectious diseases. With moderate progress, it has become clear in recent years that complex diseases require sophisticated solutions. A significant hurdle in this process is the effective delivery of drugs to specific targets within the patient’s body to increase the drug’s efficacy and reduce the side effects common with conventional drugs. To accomplish this goal, drugs are encapsulated in or conjugated to nanocarriers and selectively delivered to their targets. Potential applications include immunization, delivering anti-cancer drugs to tumors, antibiotics to infections, targeting resistant bacteria, and delivering therapeutic agents to the brain. Despite this great promise and potential, drug delivery systems have yet to be established, mainly due to their limitations in physical instability and rapid clearance by the host’s immune response. Recent interest has focused on using red blood cells (RBC) as drug carriers due to their naturally long circulation time, flexible structure, and direct access to many target sites. This includes coating nanoparticles with the membrane of red blood cells and the fabrication and manipulation of liposomes made from the red blood cells’ cytoplasmic membrane. The properties of these erythrocyte liposomes, such as charge and elastic properties, can be tuned through the incorporation of synthetic lipids to optimize physical properties, loading efficiency, and retention of different drugs. Specificity can be established through the anchorage of antigens and antibodies in the liposomal membrane to achieve targeted delivery. Although still at an early stage, this erythrocyte-based platform shows promising results in vitro and in animal studies. A large part of the challenge is related to material science, involving the manipulation of biological materials at the molecular level. I will review the current status and recent progress in the field.