Is nanomedicine still promising?

Abstract

A recent study by Mann et al. [1] published in Oncotarget exploits the use of aptamers as a targeting ligand to develop site-specific delivery of liposomal nanocarriers. It has already been 17 years, since an article titled ‘Liposomes revisited’ was published co-authored by Lasic and Papahadjopoulos [2]. In essence, this publication marked the launch of the first success story of nanomedicine into the clinic and the beginning of an entire field. However, this was not an accident. The successful development of sterically stabilized liposomes was the product of 30 years of intensive research, since Bangham first discovered in the early 1960s that phospholipids in water form a vesicle enclosed in a bilayered lipid membrane [3, 4]. Not surprisingly, a pubmed search of the word ‘liposome’ resulted in 14,858 articles published between 1965 and 1995. The focus of these studies ranged from the in vitro particle stability to the effect of size, lipid composition and polymer coating of liposomes on their blood circulation, intratumoral accumulation and anticancer activity [5-7]. Furthermore, stable encapsulation of doxorubicin into the liposome with negligible leakage of the drug in blood circulation was achieved with the remote loading method against an ammonium sulfate gradient [8]. And finally voila: a PEGylated unilamellar liposome composed of rigid phosphatidylcholine and cholesterol with a diameter of about 100 nm displayed prolonged circulation time and as a result an increased intratumoral accumulation and antitumor activity [6, 7].