Mitochondrial Transfer by Photothermal Nanoblade Restores Respiration in Mammalian Cells with Dysfunctional Mitochondria

The reliable delivery of large cargo into mammalian cells could have profound impacts on cell engineering and medicine. Current techniques, such as electroporation, sonoporation, and microcapillary injection, can deliver DNAs, RNAs, and proteins into cells, but they are limited by cargo size, endosomal cargo degradation, and poor efficiency. To circumvent these problems, we invented a photothermal nanoblade. The nanoblade is a titanium-coated glass pipet that is placed near a cell membrane and heated by a laser pulse. A resulting vapor bubble generates a transient membrane incision that allows the pressure driven delivery of cargo up to 3 µm in size into cells with high efficiency and cell viability. Here, we evaluated whether the nanoblade could transfer isolated mitochondria into cells to rescue mitochondrial dysfunction. The transfer of MDA-MB-453 mitochondria into 143BTK-ρ0 cells, which lack mtDNA, do not respire, and require uridine supplementation to proliferate, resulted in the emergence of three rescued clones in uridine-free medium 2 weeks after delivery. Interestingly, clones 1 and 3 had ATP levels, oxygen consumption rates, and ETC complex activities similar to the donor and parent cells, while clone 2 continued to have abnormal levels. qRT-PCR of genes encoding anaplerotic and catapleurotic enzymes showed that rescue lines 1 and 3 were similar to the 143 BTK- parent, whereas clone 2 remained similar to the 143BTK- ρ0 cells. This distinction between the three clones was maintained in the metabolic profiling of TCA cycle and cytosolic metabolites by mass spectrometry. In conclusion, the ability of transferring functional mitochondria to cells by the photothermal nanoblade is not only important for basic research studies, but also has potential for therapies targeted at correcting mitochondrial diseases.