As reported recently in SciTech Daily, for years scientists have recognized red blood cells (RBC) as a vehicle to deliver drugs within the human body. They circulate for days and are in harmony with the body’s immune system. This is a major advantage when comparing RBC delivery to traditional vaccine development which requires a comprehensive safety trial.
Yet one aspect of RBC’s ability to transfer disease-causing microorganisms (pathogens) has been identified only recently using mouse models. Using the new approach, researchers found a significant reduction in the growth of cancerous tumors in mouse models.
The new method can also be used as a secondary measure after the initial cancer treatment.
These findings set the stage for the use of human cells to treat and prevent disease.
RBCs Have Multiple Applications
Dr. Zongmin Zhao is associated with the Mitragotri lab and co-author of a paper on the subject. Dr. Zhao stated that RBCs have been transfused safely for centuries. They boost immune responses making them an excellent alternative to traditional drug enhancement.
But in addition to transporting oxygen from the lungs to organs, RBCs assist in fighting infections. They capture pathogens that bind to their surface, neutralize them, and send the pathogens to immune cells that are stationed in the liver and spleen.
It is noteworthy that the majority of technologies using red blood cells for drug delivery are currently directed to the lungs.
The Contribution of the Wyss Institute at Harvard
A research team at Harvard has now succeeded in creating technology that utilizes red blood cells to deliver substances (antigens) to antigen-presenting cells that break up proteins in the spleen causing an immune response.
According to Wyss faculty member Dr. Samir Mitragotri, the spleen qualifies as an excellent target for generating an immune response. The spleen happens to be one of several organs where RBCs and white blood cells interact.
The new technology is called Erythrocyte-Driven Immune Targeting (EDIT). EDITs are produced in the bone marrow and can be found in the blood. They contain hemoglobin, a protein that transports oxygen from the lungs throughout the body.
The Challenges
Capillaries consist of a dense network that causes their ‘cargo’ to be sheared off from the RBCs as they are attempting to squeeze through small vessels.
The first challenge was getting antigens to adhere to RBCs firmly so they are not sheared off and can travel to the spleen. The researchers laced nanoparticles that were bound to cells with an antigenic protein that evokes an immune response.
The team then tested this new process by injecting RBCs that had been coated with the nanoparticles into mouse models.
According to reports, twenty minutes after the mice were injected, their blood had been cleared of about ninety-nine percent of the nanoparticles. The team had successfully managed to have more nanoparticles accumulate in the spleen rather than in the lungs of the mice.
The accumulation of nanoparticles in the spleen remained level for almost twenty-four hours. EDIT RBCs were unchanged proving that the RBCs delivered their ‘cargoes’ successfully and were not destroyed.
The next challenge facing the team involved the antigens and whether they cause an immune response.
For the next three weeks, EDIT was injected into one of three groups of mice once each week. The three groups were also inoculated with malignant lymphoma cells. The cells were covered with ovalbumin which is often used in vaccine experiments. Ovalbumin is a glycoprotein large enough to produce an immune response.
Upon analysis, the researchers found that tumors in the mice that received EDIT grew significantly slower than the two non-EDIT groups. The EDIT group also exhibited a lower number of cancer cells.
The slower cancer progression due to EDIT provides more time to treat the tumor before the disease proves fatal.
The team will continue its work on EDIT and will test it against other antigens. One researcher reminded us that they are still working to lengthen and improve the quality of life.
