Liposome formulations can be broadly divided into cationic, anionic and neutral subtypes. Charged liposomes are used in many different types of studies such as, blood complement studies, gene transfer studies and other biomedical applications to name a few. Cellsome® liposomes made from anionic PEGylated lipids provide certain benefits.

Anionic liposomes offer a number of attributes, relative to the challenges associated with cationic formulations such as, the administration of cationic liposomes results in higher cytotoxicity levels, both in vitro (Zhong et al., 2009) and in vivo (Balazs and Godbey, 2010). Anionic liposomes demonstrate greater stability in solution (Zhigaltsev et al., 2002, Phillips and Heydari, 1996), lead to lower aggregation when compared with neutrally charged liposomes, and have increased endocytosis when compared with cationic (Bajoria et al., 1997) and neutral liposomes.

To improve liposome stability and enhance their circulation times in the blood, a sterically-stabilized, hydrophilic polymer, polyethylene glycol (PEG), has been shown to be the optimal choice for obtaining sterically-stabilized liposomes. Using an Anionic Liposome with PEG will protect the liposomes from circulating proteins, improving their plasma clearance and enhancing their therapeutic effects.

The four products provided that are made from Anionic PEGylated Lipids provided here consist of either DSPC:Chol:DSPG:DSPE-PEG(2000) (60:30:5:5 molar ratio), DOPC:Chol:DOPG:DOPE-PEG(2000) (60:30:5:5 molar ratio), DSPC:Chol:DSPS:DSPE-PEG(2000) (60:30:5:5 molar ratio), or DOPC:Chol:DOPS:DOPE-PEG(2000) (60:30:5:5 molar ratio).