Tunneling-nanotubes (TNTs) are a kind of cell-cell communication when cells are under stress. We hypothesize that insulted cells use TNTs as a highway to transfer materials and energy to healthy cells. TNTs transfer cellular compartments, such as endoplasmic reticulum (ER), mitochondria, Golgi and endosomes. Some cytotoxic particles, such as intracellular and extracellular amyloid β (Aβ), scrapie prion protein (PrP(Sc)) and human immunodeficiency virus (HIV)-1, are suggested to transfer with TNTs as well. p53, epidermal growth factor receptor (EGFR), Akt, phosphoinositide 3-kinase (PI3K) and mTOR are important for TNT induction. However, currently our understanding of TNTs is greatly limited. Further studies need to be done to improve our knowledge of the mechanisms and physiological functions of TNTs.