Intercellular organelle trafficking by membranous nanotube connections: a possible new role in cellular rejuvenation?

Cells could make actin-based filopodial extensions that connect up with other cells. Such close-ended, actin-based filopodial bridges, or cytonemes, have been observed during developmental and pathological processes. On the other hand, tunneling nanotubes (TNTs) form conduits with open ends that allow transfer of cytoplasmic materials and organelles between cells. The past years have witnessed the description of TNTs in multiple cell types, with a range of interesting physiological and pathophysiological activities. Some hints of the molecular components that drive their formations are now emerging. Recent work has further suggested that TNTs could be important in regenerative transfer of large cellular components, including organelles such as mitochondria and lysosomes between senescing and younger cell types (at least for cells in culture). These findings have intriguing implications in cell biology and regenerative medicine.