Leukocyte-Like Nanoparticles May Revolutionize Targeted Drug Delivery

Hybrid nanoparticles composed of a drug-loaded silicon core coated with natural white blood cell membrane lipids and proteins deliver a toxic load by readily evading the immune system, crossing the biological barriers of the body and localizing at target tissues.

Investigators at the Methodist Hospital Research Institute (Houston, TX, USA) were searching for ways to deliver nanoparticles to specific disease sites without arousing an immune response that would remove the particles from the circulation.

In a paper published in the January 2013 issue of the journal Nature Nanotechnology they described the development of novel hybrid particles composed of a core of nanoporous silicon—which could be loaded with the drug of choice—that was coated with cellular membranes purified from leukocytes. These novel bioactive particles were dubbed "LeukoLike Vectors" or LLVs.

Experimental evidence revealed that LLvs could avoid being cleared by the immune system. They communicated with endothelial cells through receptor–ligand interactions, and transported and released a drug payload across an inflamed reconstructed endothelium. Moreover, LLVs retained their functions when injected in vivo, showing enhanced circulation time and improved accumulation in a tumor.

"Our goal was to make a particle that is camouflaged within our bodies and escapes the surveillance of the immune system to reach its target undiscovered," said senior author Dr. Ennio Tasciotti, professor of nanomedicine at the Methodist Hospital Research Institute. "We accomplished this with the lipids and proteins present on the membrane of the very same cells of the immune system. We transferred the cell membranes to the surfaces of the particles and the result is that the body now recognizes these particles as its own and does not readily remove them."

"LLVs are dotted with proteins that help the particles reach specific targets, from inflamed or damaged tissues to cancer cells recruiting blood vessels," said Dr. Tasciotti. "Over time the membrane lipids and proteins will break away, leaving the nanoparticles to degrade naturally after releasing their payload. I expect this technology to become a new player in the crowded world of drug delivery system thanks to the opportunities it offers for the personalization of drug therapies."

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Methodist Hospital Research Institute