Trans-dermal and intra-dermal liposomes formulated into cosmeceuticals can enhance delivery of actives to skin. The content of phosphatidylcholine in liposomes is critical in modulating liposomes’ performance.

Cosmeceuticals are active skincare.

Cosmeceuticals are legally classified as skincare; structurally, they are made with active ingredients which may be present in medicines or with delivery systems that are supposed to improve penetration into the skin.

Because they are classified as cosmetics, no medicinal virtue can be claimed for cosmeceuticals, even when their ingredients and formulations and reported effects are similar to those of medicines. This unique status of cosmeceuticals makes them the most practical testing ground for future new medicinals since they can act as a pre-screening theater for developing new ingredients and delivery systems and re-evaluating well-known ingredients for new applications.

Because of the extremely high cost and tight regulation of medicinal pre-screening, ingredients for potential new medicines can be more effectively pre-screened as actives when they are formulated in cosmeceuticals. Potential new medicines with good testing records from cumulative scientific objective and subjective studies can cost-effectively emerge from the cosmeceutical industry.

Liposomes are more than delivery vehicles of actives in cosmeceuticals.

Among the most effective delivery systems are liposomes. For several decades now, liposomes have had a good track record as delivery systems. They can be tailored for specific applications and can work with both water-soluble and oil-soluble ingredients. For detailed, illustrated information about liposome and phospholipid structure, please visit http://www.elsomresearch.com/learning/technology/nanosomes.pdf.

• Liposomes can be made in different sizes and can be comprised of a variety of phospholipids, which are the building blocks of both cell membranes and liposomes.

• Anionic or cationic additives to liposomes can give them specific affinity to targets with the opposite charge.

• Antibodies can be incorporated into the liposomes for highly-specific targeting of cancer cells to which the liposomes are delivering a drug.

• Liposome integrity can be modulated by adding structural molecules such as cholesterol into the lipid bilayer.

• Fusogenic liposomes can be made that merge with the cell membrane and then inject all their content into the cell.

• Exchange liposomes can be made such that the liposome and the cell remain separate entities but can exchange ingredients between them.

• Symmetric and asymmetric bilayers can be designed such that the outer liposome leaflet is similar to or different from the inner leaflet so that there are different phospholipids on the inside and on the outside.

• Liposomes can be made such that materials can better flip-flop from the inner to the outer leaflet and vice versa.

Liposomes are very small. Most cannot be seen without a special microscope setting and some are too small for light microsope resolution, but their structures and the factors affecting them can be understood as clearly as are the structures of familiar, large, easily-seen materials. In building a concrete wall, where cement has rigidity and good resistance to pressure and iron has elasticity and good resistance to stretching, the two can be combined to withstand pressure and stretching. If the wall is only concrete, it will crack and crumble; if it is only iron, it will bend. The integrity of the cell membrane and liposomes can be explained similarly, where the phospholipids are like the iron and the added material such as cholesterol is like the cement. The addition of cholesterol to a liposome has to be considered in light of the duties the liposome is intended for. For example, for very rigid liposomes, more colesterol can be added, for flexible liposomes less colesterol should be added. In addition, the legnth and unsaturation level of fatty acids in the phospholipids strongly effect the physical properties of liposomes and how fast the actives in the liposome may leak out.

Phosphatidylcholine is a critical component of active liposomes and cell membranes.

Phosphatidylcholine, found in active liposomes, is also the major phospholipid in human cell membrane; its relative content in membranes is diminished with aging. Physical, chemical, and biological properties of cell membranes are affected.

• In signal transduction, a signaling molecule such as a hormone binds with a receptor located on the cell membrane. As a result, a signal is created which is transferred into the cell in the form of cyclic-AMP. This further initiates a cascade of biochemical reactions that carry out the biological end result for that specific hormone. Binding of a hormone to a receptor is a highly specialized process; changes in the lipid composition of cell membranes, such as phosphatidylcholine or other phospholipids, can strongly affect changes in the receptor-binding ability of the hormone. With changes in the affinity of the receptor or the available number of receptors exposed or accessible to the hormone on the cell membrane, the biochemical cascade of events triggered by the hormone binding to the receptor can be interrupted.

• Cell membranes are semi-permeable, which means that they allow certain molecules to permeate but prevent entry of other molecules. This selective ability is critical to maintaining a healthy cell. Age-related decrease in the relative content of phosphatidylcholine in cell membranes can result in losing the differential ability to internalize or exclude specific molecules into and out of the cell; this can be critical to the cell’s well-being. With aging, important ingredients may not penetrate well, and unwanted materials may be entering the cell.

• Changes in the cell membranes can affect the cell and changes in the cell can affect the organ and the whole organism. Increase in phosphatidylcholine in aging organisms’ cell membranes could reverse some of these age-related deficiencies.

For detailed information about phospholipids and liposomes and the role of phosphatidylcholine in the aging process, please read http://www.elsomresearch.com/learning/technology/nanosomes.pdf.

Liposomes carrying drugs can be injected into the bloodstream, but the problem is that they are cleared from the circulatory system in a very short time – minutes to hours – depending on the liposomes. In “Relationship between biological and physical properties of cells and the lipid composition of their membranes – aspects in aging processes” (1983), I showed that very small liposomes made of phosphatidylcholine can circulate in the blood stream for at least a week, which is a critical advantage in their use as drug delivery vehicles. Topical Nanosomes™ - very small liposomes – are highly effective in topical delivery of drugs and actives and can be used in cosmeceuticals for the delivery of actives into the skin.

Liposome technology is currently revisited with new focus as a result of emerging new technologies and applications. Nano-biotechnologies are among the major reasons the liposome field is drawing new interest and new hopes. Topical Nanosomes™ are at the frontier of nano-biotechnologies as intra-dermal and trans-dermal vehicles.