High Sensitivity Differential Scanning Calorimetry Study of DNA-Cationic Liposome Complexes

Key considerations in formulation development for gene therapy products

Gene therapy emerged as an important area of research and led to the success of multiple product approvals in the clinic. The number of clinical trials for this class of therapeutics is expected to grow over the next decade. Gene therapy products are complex and heterogeneous, employ different types of vectors and are susceptible to degradation. The product development process for commercially viable gene-based pharmaceuticals remains challenging. In this review, challenges, stability, and drug product formulation development strategies using viral or non-viral vectors, as well as accelerated regulatory approval pathways for gene therapy products are discussed.

Structural behavior of amphiphilic polyion complexes interacting with saturated lipid membranes investigated by coarse-grained molecular dynamic simulations

Neutral polyelectrolyte complexes (PECs) made from an amphiphilic multiblock copolymer of type (A_nB_n)_m and an oppositely charged polyion and interacting with a dipalmitoylphosphatidylcholine (DPPC) lipid membrane.

Hepatitis B virus S gene therapy with 10-23 DNAzyme delivered by chitosan-g-stearic acid micelles

DrzBS, which targets HBV S gene expression, has important research significance and potential application value. CSO-SA is a safe and efficient non-viral gene carrier and CSO-SA/DrzBS micelles are a promising application for anti-HBV gene therapy.

Biocompatible cationic lipids for the formulation of liposomal DNA vectors

Ethylphosphocholine lipids are highly biocompatible cationic amphiphiles that can be used for the formulation of liposomal DNA vectors, with negligible toxic effects on cells and organisms. Here we report the characterization of EDPPC (1,2-dipalmitoyl-sn-glycero-O-ethyl-3-phosphocholine chloride) liposomes, containing two different zwitterionic helper lipids, POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and DOPE (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine). Depending on the nature of the helper lipid, a phase separation in the bilayer is found at room temperature, where domains enriched in the cationic component coexist in a relatively large temperature range with regions where the zwitterionic lipids are predominant. We studied DNA complexation, the internal structure of lipoplexes and their docking and fusogenic ability with model target bilayers. The structural and functional modifications caused by DNA binding were studied using Dynamic Light Scattering (DLS), zeta potential, and small and wide angle X-ray scattering (SAXS-WAXS) measurements, while the interaction with membranes was assessed by using Giant Unilamellar Vesicles (GUVs) as model target bilayers. The results presented establish a connection between the physicochemical properties of lipid bilayers, and in particular of lipid demixing, with the phase state of the complexes and their ability to interact with model membranes.

Nucleic acid-lipid membrane interactions studied by DSC

The interactions of nucleic acids with lipid membranes are of great importance for biological mechanisms as well as for biotechnological applications in gene delivery and drug carriers. The optimization of liposomal vectors for clinical use is absolutely dependent upon the formation mechanisms, the morphology, and the molecular organization of the lipoplexes, that is, the complexes of lipid membranes with DNA. Differential scanning calorimetry (DSC) has emerged as an efficient and relatively easy-to-operate experimental technique that can straightforwardly provide data related to the thermodynamics and the kinetics of the DNA-lipid complexation and especially to the lipid organization and phase transitions within the membrane. In this review, we summarize DSC studies considering nucleic acid-membrane systems, accentuating DSC capabilities, and data analysis. Published work involving cationic, anionic, and zwitterionic lipids as well as lipid mixtures interacting with RNA and DNA of different sizes and conformations are included. It is shown that despite limitations, issues such as DNA- or RNA-induced phase separation and microdomain lipid segregation, liposomal aggregation and fusion, alterations of the lipid long-range molecular order, as well as membrane-induced structural changes of the nucleic acids can be efficiently treated by systematic high-sensitivity DSC studies.

Microcalorimetric, spectroscopic and microscopic investigation on the toxic effects of CdTe quantum dots on Halobacterium halobium R1

The biological effect of CdTe quantum dots (QDs) on Halobacterium halobium R1 (H. halobium R1) growth was analyzed by a microcalorimetric technique. By using a TAM air eight channels microcalorimeter, the thermogenic curves of H. halobium R1 growth were obtained at 37 °C. To analyze the results, the maximum heat power (P(m)) and the growth rate constants (k) were determined, which showed that they were correlated to the concentration of QDs. The addition of quantum dots caused a gradual increase of P(m) and k at low concentrations of QDs, and a conspicuous decrease at high concentrations. For confirmation, the turbidity (OD(600)) and respiratory rate at different concentrations of QDs were studied. The morphology of H. halobium R1 cells both in the absence and presence of QDs was examined by transmission electron microscopy (TEM). The results of these studies were corroborated with ones derived from microcalorimetry. In this work, the mechanism of cytotoxicity of QDs was explored through fluorescence spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS) and microcalorimetry. It was clear that metabolic mechanism of H. halobium R1 growth was changed by the addition of QDs. To the best of our knowledge, the thermokinetics and toxicology of CdTe QDs against H. halobium R1 were obtained for the first time by microcalorimetry.

Advancing nonviral gene delivery: lipid- and surfactant-based nanoparticle design strategies

Gene therapy is a technique utilized to treat diseases caused by missing, defective or overexpressing genes. Although viral vectors transfect cells efficiently, risks associated with their use limit their clinical applications. Nonviral delivery systems are safer, easier to manufacture, more versatile and cost effective. However, their transfection efficiency lags behind that of viral vectors. Many groups have dedicated considerable effort to improve the efficiency of nonviral gene delivery systems and are investigating complexes composed of DNA and soft materials such as lipids, polymers, peptides, dendrimers and gemini surfactants. The bottom-up approach in the design of these nanoparticles combines components essential for high levels of transfection, biocompatibility and tissue-targeting ability. This article provides an overview of the strategies employed to improve in vitro and in vivo transfection, focusing on the use of cationic lipids and surfactants as building blocks for nonviral gene delivery systems.