Synthetic blood gets closer to reality

Scientists have developed particles that closely mirror some of the key properties of red blood cells, potentially helping pave the way for the development of synthetic blood.

The new discovery could also lead to more effective treatments for life threatening medical conditions such as cancer.

University of North Carolina at Chapel Hill researchers used technology known as PRINT (Particle Replication in Non-wetting Templates) to produce very soft hydrogel particles that mimic the size, shape and flexibility of red blood cells, allowing the particles to circulate in the body for extended periods of time.

PRINT Process (Image: Joseph M. DeSimone )
Tests of the particles’ ability to perform functions such as transporting oxygen or carrying therapeutic drugs have not been conducted, and they do not remain in the cardiovascular system as long as real red blood cells.

However, the researchers believe the findings – especially regarding flexibility – are significant because red blood cells naturally deform in order to pass through microscopic pores in organs and narrow blood vessels.

Over their 120-day lifespan, real cells gradually become stiffer and eventually are filtered out of circulation when they can no longer deform enough to pass through pores in the spleen.

The team also tested the particles to determine their ability to circulate in the body without being filtered out by various organs.

When tested in mice, the more flexible particles lasted 30 times longer than stiffer ones. Stiffness also influenced where particles eventually ended up: more rigid particles tended to lodge in the lungs, but the more flexible particles did not; instead, they were removed by the spleen, the organ that typically removes old real red blood cells.

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Beyond moving closer to producing fully synthetic blood, the findings could affect approaches to treating cancer.

Cancer cells are softer than healthy cells, enabling them to lodge in different places in the body, leading to the disease’s spread. Particles loaded with cancer-fighting medicines that can remain in circulation longer may open the door to more aggressive treatment approaches.

The findings were reported in the journal Proceedings of the National Academy of Sciences. (ANI)

Timothy J. Merkel, Stephen W. Jones, Kevin P. Herlihy, Farrell R. Kersey, Adam R. Shields, Mary Napier, J. Christopher Luft, Huali Wu, William C. Zamboni, Andrew Z. Wang, James E. Bear, and Joseph M. DeSimone
Using mechanobiological mimicry of red blood cells to extend circulation times of hydrogel microparticles
PNAS published ahead of print January 10, 2011, doi:10.1073/pnas.1010013108

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