For decades, mitochondria have been considered as “a cellular power plant” to generate ATP through oxidative phosphorylation and capable of energizing cellular activities.
Mitochondria are usually located in the cytoplasm of cells. Recently, Dr. Yong Zhao’s lab, at Center for Discovery and Innovation, found circulating mitochondria in human and animal blood. Electron microscopy confirmed the presence of mitochondria in adult human blood plasma. Flow cytometry analyses demonstrated that circulating mitochondria from the plasma of human cord blood and adult peripheral blood displayed the immune tolerance-associated membrane molecules such as CD270 and PD-L1 (programmed cell death-ligand 1). Similar data were obtained from fetal bovine serum (FBS) and horse serum of different vendors. Mitochondria remained detectable even after 56 ◦C heat inactivation. These findings suggested that the existence of circulating mitochondria in blood may function as a novel mediator, leading to the energy balance and cross-talk among cells, tissues, and organs, and maintenance of homeostasis. Additionally, plasma-related products should be cautiously utilized in cell cultures and clinical studies due to the mitochondrial contamination. This work has been published in peer-reviewed journal International Journal of Molecular Sciences.