Cholesterol domains in cationic lipid/DNA complexes improve transfection

Abstract

The interaction between the cationic lipid DOTAP and cholesterol is examined in high cholesterol formulations by differential scanning calorimetry (DSC). Preparation of liposomes above 66 mol% cholesterol results in formulations that exhibit a calorimetric transition for anhydrous cholesterol at 38-40 degrees C. The enthalpy of this transition progressively increases at higher cholesterol contents, and is not detected below 66 mol% cholesterol. Furthermore, the enthalpy changes indicate that the composition of the non-domain forming portion containing DOTAP saturated with cholesterol is relatively constant above 66 mol% cholesterol. Greater transfection efficiency in the presence of 50% serum is observed at the formulations with high cholesterol contents where anhydrous cholesterol domains are detected by DSC. Although formulations possessing higher cholesterol exhibited a greater resistance to serum-induced aggregation, maintenance of small particle size does not appear to be responsible for the enhanced transfection efficiency. Additional studies quantifying albumin binding suggest that cholesterol domains in the lipid/DNA complex do not bind protein, and this may enable these moieties to enhance transfection by facilitating membrane fusion.

Stabilization of Plasmid DNA and Lipid-Based Therapeutics as Dehydrated Formulations

“…Cholesterol is often included in liposomal formulations to increase the rigidity of the bilayer and increase transfection efficiency of lipid-nucleic acid complexes [213,[225][226][227]. The effect of the addition of cholesterol on the oxidative degradation of liposomal formulation is not consistent and appears to depend on the composition of the liposomal formulation and the temperature at which the study was conducted [228].…”

Cationic lipid-mediated nucleic acid delivery: beyond being cationic

“…Detailed investigations with structural analogues of many of these modules indicated that the best efficiency is an outcome of the total structure and an optimized module need not work with other modules (Simberg et al, 2004). Excellent reviews on cationic lipids have been published cataloguing their chemical structures, phase properties, biophysical properties and structure-transfection efficiency relations (Garinot et al, 2007;Koynova et al, 2007Koynova et al, , 2009Middaugh and Ramsey, 2007;Xu and Anchordoquy, 2008).…”

“…DOPE is the most popular colipid in transfection formulations. Cholesterol is another popular colipid (Ramezani et al, 2009;Xu and Anchordoquy, 2008). From detailed investigations into the analogues of DOPE and other phospholipids it is clear that the presence of DOPE facilitates in cell interaction and escape from the endosomes Zuhorn et al, 2007).…”

“…Presence of cholesterol apparently stabilizes the lipoplexes in the presence of serum. Serum has a disintegration effect on the lipoplexes; however cholesterol, probably by forming domains, reduces the interaction of proteins onto the lipoplex which is a prerequisite for disintegration (Xu and Anchordoquy, 2008).…”

Exploitation of De Novo Helper-Lipids for Effective Gene Delivery.

“…The serum protein bound to the cationic lipoplexes electrostatically, and the lipoplexes has been reported to reduce their transfection efficiency in the presence of FBS (34,35).…”