Red bloodcells are cells that take oxygen from the lungs and carry it to body tissues. These disk-shaped cells contain millions of molecules of hemoglobin, an iron-containing protein. Red blood cells are highly flexible, allowing them to squeeze through tiny capillaries and then expand to their former shape. Cells also contain proteins on their surface that allow them to circulate in blood vessels for a long time without being engulfed by immune cells.
There have been several attempts to develop synthetic red blood cells that reproduce the positive properties of natural ones, such as flexibility, the ability to transport oxygen and long circulation times. But so far, most synthetic red blood cells have had one or a few of those characteristics, never all of them.
The team, made up of, among others, Wei Zhu, from the Technological University of South China, and C. Jeffrey Brinker, from the University of New Mexico in the United States, set out to produce artificial red blood cells that had properties similar to those of natural, but could also perform new tasks such as drug administration, magnetic guidance and toxin detection.
The researchers made the synthetic cells by first coating the donated human red blood cells with a thin layer of silica. They placed positively and negatively charged polymers on the red blood cells with silica. They then obtained the flexible replicas and their surface was covered with natural red blood cell membranes.
Synthetic red blood cells, like the one shown here, could carry oxygen, drugs, and other loads through the bloodstream. The scale bar measures 2 micrometers. (Image: Adapted from ACS Nano 2020, DOI: 10.1021 / acsnano.9b08714)
The thus obtained synthetic red blood cells were similar to natural cells in size, shape, charge and surface protein, and could pass through the model capillaries without losing their shape. In mice, synthetic red blood cells lasted more than 48 hours, with no observable toxicity.
The researchers loaded the synthetic red blood cells with hemoglobin, an anticancer drug, a toxin sensor, or magnetic nanoparticles, to demonstrate their ability to carry charges.
The team also demonstrated that the new synthetic red blood cells can act as a “decoy” for a bacterial toxin.Future research is planned to explore the potential of synthetic red blood cells and other artificial cells in medical applications such as cancer therapy and toxin detection.