Mineralized vectors for gene therapy

There is an intense interest in developing materials for safe and effective delivery of polynucleotides using non-viral vectors. Mineralization of organic templates has long been used to produce complex materials with outstanding biocompatibility. However, a lack of control over mineral growth has limited the applicability of mineralized materials to a few in vitro applications. With better control over mineral growth and surface functionalization, mineralized vectors have advanced significantly in recent years. Here, we review the recent progress in chemical synthesis, physicochemical properties, and applications of mineralized materials in gene therapy, focusing on structure-function relationships. We contrast the classical understanding of the mineralization mechanism with recent ideas of mineralization. A brief introduction to gene delivery is summarized, followed by a detailed survey of current mineralized vectors. The vectors derived from calcium phosphate are articulated and compared to other minerals with unique features. Advanced mineral vectors derived from templated mineralization and specialty coatings are critically analyzed. Mineral systems beyond the co-precipitation are explored as more complex multicomponent systems. Finally, we conclude with a perspective on the future of mineralized vectors by carefully demarcating the boundaries of our knowledge and highlighting ambiguous areas in mineralized vectors. STATEMENT OF SIGNIFICANCE: Therapy by gene-based medicines is increasingly utilized to cure diseases that are not alleviated by conventional drug therapy. Gene medicines, however, rely on macromolecular nucleic acids that are too large and too hydrophilic for cellular uptake. Without tailored materials, they are not functional for therapy. One emerging class of nucleic acid delivery system is mineral-based materials. The fact that they can undergo controlled dissolution with minimal footprint in biological systems are making them attractive for clinical use, where safety is utmost importance. In this submission, we will review the emerging synthesis technology and the range of new generation minerals for use in gene medicines.

Effect of hydrophobic tails of plier-like cationic lipids on nucleic acid delivery and intracellular trafficking

In the optimization of transfection efficacy, one of the crucial barriers to effective gene delivery is in fact the intracellular trafficking of nucleic acids, besides the first and the last steps of gene transfer, i.e., delivery to the cell and transcription. Modifications of cationic lipid structure have been reported to have a significant effect on gene delivery. Therefore, the plier-like cationic lipids (PCLs) have been synthesized and the effect of the different types of hydrophobic tails (chain length and unsaturated hydrocarbon) on physicochemical properties, cellular uptake, trafficking process, transfection, and silencing efficiency has been investigated. In this study, the plier-like cationic niosomes (PCNs) containing PCL (A, B, and C) were evaluated their performance to deliver pDNA and siRNA to HeLa cells. Among the PCNs, PCN-B with saturated asymmetric hydrocarbon tails (C18 and C12) provided the highest efficiency for pDNA and siRNA delivery. Furthermore, the results revealed that the structure of the cationic lipids affected the internalization pathway and the intracellular trafficking. PCL-B and PCL-C with asymmetric tails preferred clathrin- and caveolae-mediated endocytosis as the predominant internalization pathways and were also involved in the polymerization process for transfection. However, PCL-A with symmetry hydrocarbon tails (C12) was predominantly taken up via macropinocytosis. All PCNs were able to escape from endosomal-lysosomal systems through facilitation of acidification. Results obtained from the cytotoxicity test revealed that the PCNs were safe in vitro. Therefore, PCNs provide a great prospect as an alternative effective gene delivery system.