Nanoparticles Direct White Blood Cells to Incorporate Therapeutic Reagents

A nanoparticle-based delivery system has been developed that targets specific blood cells, traps them, and then induces them to incorporate small-interfering RNA (siRNA), proteins, or drugs.

The nanoparticle strategy is based on the property of white blood cells to adhere transiently to proteins known as selectins while they roll along the walls of blood vessels before leaving the bloodstream to fight disease or infection.

Biomedical engineers from Cornell University (Ithaca, NY, USA) covalently attached P-selectin to the surface of nanoscale liposomes to create targeting nanoparticles (NPs). SiRNA was loaded into these nanoscale liposomes, and the liposomes were stabilized by PEGylation with DSPE-PEG2000. The NPs were used to coat a shunt that could be inserted into a blood vessel.

Results of experiments using this system were published in the June 25, 2009, online edition of the journal Gene Therapy. The investigators reported that the coated surface of the shunt specifically captured targeted cells from the circulation, efficiently delivered encapsulated siRNA into the adherent cells, and dramatically silence the targeted gene neutrophil elastase. The device created a highly localized concentration of particles for siRNA delivery into the circulatory system, providing circulating target cells adequate time to interact with therapeutic materials.

"This study greatly extends the range of therapies,” said senior author Dr. Michael King, associate professor of biomedical engineering at Cornell University. "We can introduce just about any drug or genetic material that can be encapsulated, and it is delivered to any circulating cells that are specifically targeted.”

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