Abstract
BackgroundSix new cationic gemini lipids based on cholesterol possessing different positional combinations of hydroxyethyl (-CH2CH2OH) and oligo-oxyethylene -(CH2CH2O)n- moieties were synthesized. For comparison the corresponding monomeric lipid was also prepared. Each new cationic lipid was found to form stable, clear suspensions in aqueous media.Methodology/Principal FindingsTo understand the nature of the individual lipid aggregates, we have studied the aggregation properties using transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential measurements and X-ray diffraction (XRD). We studied the lipid/DNA complex (lipoplex) formation and the release of the DNA from such lipoplexes using ethidium bromide. These gemini lipids in presence of a helper lipid, 1, 2-dioleoyl phophatidyl ethanol amine (DOPE) showed significant enhancements in the gene transfection compared to several commercially available transfection agents. Cholesterol based gemini having -CH2-CH2-OH groups at the head and one oxyethylene spacer was found to be the most effective lipid, which showed transfection activity even in presence of high serum levels (50%) greater than Effectene, one of the potent commercially available transfecting agents. Most of these geminis protected plasmid DNA remarkably against DNase I in serum, although the degree of stability was found to vary with their structural features.Conclusions/Significance-OH groups present on the cationic headgroups in combination with oxyethylene linkers on cholesterol based geminis, gave an optimized combination of new genera of gemini lipids possessing high transfection efficiency even in presence of very high percentage of serum. This property makes them preferential transfection reagents for possible in vivo studies.
Highlights
Gene therapy is a promising method in modern medicinal research, which employs ‘‘Gene as medicine’’ [1]
Transmission Electron Microscopy (TEM) studies further indicate that CholHG-1ox gives liposomes of lowest in size whereas CholHG-3ox affords liposomes that are largest in size
Representative negativestain TEM images of aqueous suspensions of lipoplexes of CholHG-1ox, CholHG-3ox and CholHG-D at optimized lipid/ dioleoyl phophatidyl ethanol amine (DOPE) and N/P ratio are shown in the Figure S1
Summary
Gene therapy is a promising method in modern medicinal research, which employs ‘‘Gene as medicine’’ [1]. This line of treatment offers new hope for survival against many diseases which have genetic origins like cancer [2], diabetes [3], cystic fibrosis [4], AIDS [5] and cardiovascular diseases [6] etc This strategy has broadened the scope of playing with the genetic material to avoid, remove or replace the fundamental cause of the diseases by delivering the desired genes or oligonucleotides or by blocking the ‘disease-causing’ sequence from transcription and translation. Positive charge on the surfaces of cationic lipid/DNA complexes results in a non-specific adsorption of negatively charged plasma proteins in serum leading to the loss of transfection efficiency [25]. For this reason to develop a structure-activity relationship (SAR), most of the transfection experiments are performed in absence of serum in vitro. Each new cationic lipid was found to form stable, clear suspensions in aqueous media
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
