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Posted: Jun 15, 2011
Using living cells as an 'invisibility cloak' for drug delivery
(Nanowerk News) The quest for better ways of encapsulating medicine so that it can reach diseased parts of the body has led scientists to harness — for the first time — living human cells to produce natural capsules with channels for releasing drugs and diagnostic agents. The report appears in ACS' journal Nano Letters ("Cells as Factories for Humanized Encapsulation").
Until now, biocompatible surface processing has typically relied on PEGylation and other surface coatings, which, however, cannot minimize clearance by macrophages or the renal system but may also increase the risk of chemical side effects. Cell membranes provide a generic and far more natural approach to the challenges of encapsulation and delivery in vivo.
In the report, Dayang Wang and colleagues explain that the human body is very efficient at getting rid of foreign substances. Some foreign substances, such as viruses, are harmful and should be removed. But the body also considers drugs and nanoparticles — meant to treat diseases and allow physicians to see cells and organs — to be foreign objects, and they are also quickly removed. To help these substances stay in the body longer, scientists have tried to fool it by encapsulating these substances in coatings that more closely resemble natural cells. Over the years, researchers have tested many different artificial coatings, but they failed to stay in the body for very long. So, Wang and colleagues set out to make a better capsule — by using living cells as an "invisibility cloak".
Because the group's so-called "cell membrane capsules" (CMCs) were made from real living cells, they tricked the body into thinking they were supposed to be there. Thus, drugs and nanoparticles inside CMCs stayed in the body much longer than those inside other encapsulation materials. "Hence the CMCs provide the first intrinsically biocompatible and functional drug delivery and release vehicles," say the researchers.