Scientists create synthetic red blood cells to help deliver drugs

Scientists at the University of California at Santa Barbara and the University of Michigan have created artificial red blood cells to help deliver drugs, overcoming decades of attempts to mimic natural red blood cells.

Scientists at the University of California at Santa Barbara and the University of Michigan have created artificial red blood cells to help deliver drugs, overcoming decades of attempts to mimic natural red blood cells.

In many ways, red blood cells are the keys to the body's circulation system. The flexible, double-concave discs carry oxygen through the body, and have a shape that, until now, has been difficult for scientists to reproduce.

The researchers were able to create biodegradable, biocompatible particles with the same size, shape and flexibility of red blood cells. The researchers say the synthetic red blood cells retain 90 percent of their oxygen-binding capacity after a week. Better still, they can deliver therapeutic drugs effectively and with controlled release, as well as carry dyes for diagnostic imaging.

"This ability to create flexible biomimetic carriers for therapeutic and diagnostic agents really opens up a whole new realm of possibilities in drug delivery and similar applications," UCSB chemical engineering professor Samir Mitragotri said in prepared remarks. "We know that we can further engineer sRBCs to carry additional therapeutic agents, both encapsulated in the sRBC and on its surface."

The researchers created the cells by first making a polymer doughnut-shaped template, coating it with up to nine layers of hemoglobin and other proteins and then removing the core template. The resulting particles have the same size and flexibility, and can carry as much oxygen, as natural red blood cells, the researchers said.

Technology Review describes the process in detail:

To create the synthetic cells, Mitragotri, along with researchers at the University of Michigan, start with spherical particles made of a common polymer called poly(lactic-co-glycolic acid (PLGA), a compound known for its biocompatible and biodegradable properties. They expose the spheres to rubbing alcohol, which causes them to deflate and collapse into the dimpled shape of a red blood cell. The hard PLGA particle acts as a mold, around which the researchers can deposit layer after layer of proteins. They crosslink the proteins to get them to hold to the PLGA, then dissolve the rigid inner structure. The result is a soft, flexible protein shell the size and shape of a red blood cell. The researchers can also vary the protein coatings depending, for example adding hemoglobin, which could carry oxygen.

That's important because such flexibility is absent in existing polymer-based biomaterials used as carriers for drugs and dyes, giving the artificial red blood cells the ability to flow through capillaries smaller than their diameter -- just like natural red blood cells.

The technique can also be used to develop particles that mimic the shape and properties of diseased cells, such as those found in sickle-cell anemia and hereditary eliptocytosis, allowing for a greater understanding of the implications of those diseases.

The challenge, however, is to keep the synthetic blood cells in circulation. The body is very good at rapidly filtering out particles that do not belong in the circulation system, and previous versions of artificial red blood cells were proved ineffective after the body purged them from the blood.

The team's research was published in the Proceedings of the National Academy of Sciences.

This post was originally published on Smartplanet.com

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