Triggered release of siRNA from poly(ethylene glycol)-protected, pH-dependent liposomes.
The ability of small interfering RNA (siRNA) to regulate gene expression has potential therapeutic applications, but its use is limited by inefficient delivery. Triggered release of adsorbed poly(ethylene glycol) (PEG)-b-polycation polymers from pH-dependent (PD) liposomes enables protection from immune recognition during circulation (pH 7.4) and subsequent intracellular delivery of siRNA within the endosome (pH ~5.5). Polycationic blocks, based on either poly[2-(dimethylamino)ethyl methacrylate] (31 or 62 DMA repeat units) or polylysine (21 K repeat units), act as anchors for a PEG (113 ethylene glycol repeat units) protective block. Incorporation of 1,2-dioleoyl-3-dimethylammonium-propane (DAP), a titratable lipid, increases the liposome's net cationic character within acidic environments, resulting in polymer desorption and membrane fusion. Liposomes encapsulating siRNA demonstrate green fluorescent protein (GFP) silencing in genetically-modified, GFP-expressing HeLa cells and glyceraldehyde-3-phosphate dehydrogenase (GAPD) knockdown in human umbilical vein endothelial cells (HUVEC). Bare and PD liposomes coated with PEG113-DMA31 exhibit a 0.16+/-0.2 and 0.32+/-0.3 fraction of GFP knockdown, respectively. In contrast, direct siRNA administration and Oligofectamine complexed siRNA reduce GFP expression by 0.06+/-0.02 and 0.14+/-0.02 fractions, respectively. Our in vitro data indicates that polymer desorption from PD liposomes enhances siRNA-mediated gene knockdown.
Auguste
Debra T
DT
Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Furman
Kay
K
Wong
Andrew
A
Fuller
Jason
J
Armes
Steven P
SP
Deming
Timothy J
TJ
Langer
Robert
R
D000327:Adsorption; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D015870:Gene Expression; D018014:Gene Transfer Techniques; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000138:chemical synthesis / Q000737:chemistry*; D008689:Methacrylates / Q000737:chemistry; D010316:Particle Size; D010713:Phosphatidylcholines / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010718:Phosphatidylserines / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry*; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000737:chemistry / Q000235:genetics; D012235:Rhodamines / Q000737:chemistry
D008055:Lipids; D008081:Liposomes; D008689:Methacrylates; C053685:N-(lissamine rhodamine B sulfonyl)-1,2-dioleoylphosphatidylethanolamine; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D034741:RNA, Small Interfering; D012235:Rhodamines; C484027:oligofectamine; C421283:poly(ethylene glycol)-dimethacrylate; D049452:Green Fluorescent Proteins; D011092:Polyethylene Glycols; C042077:N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)phosphatidylethanolamine; C042511:1,2-dioleoylphosphatidylserine; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; C017251:1,2-oleoylphosphatidylcholine