Cell-to-cell communication is essential for the organization, coordination, and development of cellular networks and multi-cellular systems. Intercellular communication is mediated by soluble factors (including growth factors, neurotransmitters, and cytokines/chemokines), gap junctions, exosomes and recently described tunneling nanotubes (TNTs). It is unknown whether a combination of these communication mechanisms such as TNTs and gap junctions may be important, but further research is required. TNTs are long cytoplasmic bridges that enable long-range, directed communication between connected cells. The proposed functions of TNTs are diverse and not well understood but have been shown to include the cell-to-cell transfer of vesicles, organelles, electrical stimuli and small molecules. However, the exact role of TNTs and gap junctions for intercellular communication and their impact on disease is still uncertain and thus, the subject of much debate. The combined data from numerous laboratories indicate that some TNT mediate a long-range gap junctional communication to coordinate metabolism and signaling, in relation to infectious, genetic, metabolic, cancer, and age-related diseases. This review aims to describe the current knowledge, challenges and future perspectives to characterize and explore this new intercellular communication system and to design TNT-based therapeutic strategies.

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1-Octanol-water log P values for a large number of standards and bioactive molecules have been correlated to the logarithm of the corresponding capacity factors determined by reversed-phase high-performance liquid chromatography, using a novel dynamically coated phase, containing phosphatidylcholine. Similarly a correlation was also obtained for log P and capacity factors determined by micellar electrokinetic capillary chromatography (MECC), involving the use of phosphatidylcholine--bile acid mixed micelles in the separation buffer. Statistical analysis of data obtained via both methods has shown that either method will give reliable log P predictions, although MECC is generally more useful for neutral and basic compounds. It is recommended that, as both methods can easily be set up in an analytical laboratory, their combined use provides rapid methodology for the confident estimation of hydrophobicity, as measured by log P for the widest diversity of chemical structures.

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