Abstract
According to the endosymbiotic theory, mitochondria is an organelle derived from an ancient alpha-proteobacteria that developed a symbiosis with a eukaryotic ancestor. Mitochondrial DNA (mtDNA) exists in hundreds to thousands of copies in each cell and encodes for 13 structural proteins which are subunits of respiratory chain. Mitochondria generate energy for cellular processes by producing ATP through oxidative phosphorylation. Also, they control other processes as nucleotide and heme syntheses, redox balance, calcium metabolism, waste management (urea and ROS) and apoptosis. mtDNA deletions, point mutations, thymine dimers and mtDNA depletions are strongly related with disease in humans and other mammals. Some mtDNA alterations can arise spontaneously during life spam, other can be inherited by maternal lineage as specific mutations. So, nuclear DNA mutations can produce mitochondrial disorders because while mtDNA encodes 13 proteins, mitochondria need almost 2000 proteins with structural and functional roles. In these cases, a mendelian inheritance pattern can be observed. mtDNA alterations can be produced by exposure to toxic substances or UV and high-energy radiations. mtDNA mutations are cumulative because mitochondria lack reparative mechanisms. Normal and mutant mtDNA can coexist in the same cell, a condition known as heteroplasmy. Heteroplasmy allows the persistence of an otherwise lethal mutation through generations. Mitochondrial disorders can appear as myopathies, cardiomyopathies, lactic acidosis diabetes mellitus, female’s subfertility, lipodystrophy, neuropathies as autism or Alzheimer’s diseases or haematological and renal disorders. Due to heteroplasmy, these disorders can appear with a wide range of intensities, because the mutant mtDNA needed to cause a disorder varies among organisms, among organ systems and within a given tissue, and depends on a delicate balance between ATP supply and demand. Another kind of problem surges at tissues under hypoxemic-related damage, where mitochondria play an important role in cell survival and recovery. Finally, the role played by mitochondria in cancer survival and treatment is focused in many researches.Mitochondrial disorders have not a single treatment. In the most serious cases of inherited mitochondrial diseases, the supportive treatment only improves the life quality slightly. Nowadays, the most of experimental approaches search prevents the clinical manifestations of these diseases by reducing the mutant mtDNA percentage into the oocyte or the early embryo via nuclear transfer. Artificial Mitochondrial Transfer/Transplant (AMT/T) rises as an alternative to many acquired or inherited mitochondrial disorders, both ex vivo, in vitro and in vivo conditions. The present work shows the variation of an AMT/T method -MitoCeption- in a cellular model for in vitro treatment of acquired mtDNA disorder caused by UV Radiation by using Peripheral Blood Mononuclear Cells (PBMCs) and the feasibility of the same method for ex vivo AMT/T to murine oocytes and early embryos. In the in vitro model of cell damage by UV radiation, the main results represent an upgrading in the applications of AMT/T. We showed that PBMCs could be used as a primary allogeneic mixed source of mitochondria. We also showed that these mitochondria can be transferred in a mix from different donors (PAMM) to UVR-damaged, non-adherent primary cells. Additionally, the duration of the MitoCeption protocol was reduced. On the other hand, Mitoception used on murine oocytes and early embryos probed to be a safe method for AMT/T by using human mitochondrial mix (PAMM). Murine 0ocytes’ and embryos’ exogenous mitochondrial content was observed by fluorescence microscopy and exogenous mtDNA was quantified by qPCR and 2ΔCT method. Finally, healthy murine new-borns were obtained by embryo transfer, probing that human mitochondria were removed from murine cells during embryo’s development after implantation.