Mitochondrial swelling and restorable fragmentation stimulated by femtosecond laser

Mitochondria play a key role in all cellular physiology, processes, and behaviors. It is very difficult to precisely stimulate single mitochondria noninvasively in traditional biomedical research. In this study, we report that femtosecond laser can stimulate fragmentation or swelling of single mitochondria in human mesenchymal stem cells rather than physical disruption or ablation. In experiments, fragmented mitochondria can recover normal very soon but swelling ones cannot. At the same time, laser-induced generation of mitochondrial reactive oxygen species and opening of mitochondria permeability transition pores are involved in mitochondrial responses to photostimulation. Furthermore, the localized translocation of proapoptotic molecules are found in those stimulated mitochondria. Those results suggest femtosecond-laser photostimulation as a noninvasive and precise method for mitochondrial manipulation and related research.