Microinjection of serum-starved mitochondria derived from somatic cells affects parthenogenetic development of bovine and murine oocytes.

Microinjection of isolated mitochondria into oocytes is an effective method to introduce exogenous mitochondrial DNA. In nuclear transfer procedures in which donor cell mitochondria are transferred with nuclei into recipient oocytes; development and survival rates of reconstructed embryos may be also directly influenced by mitochondrial viability. Mitochondrial viability is dramatically affected by cell culture conditions, such as serum starvation prior to nuclear transfer. This study was conducted to examine the influence of exogenous mitochondria using bovine and mouse parthenogenetic models. Mitochondria were isolated from primary cells at confluency and after serum starvation. The bovine oocytes injected with serum-starved mitochondria showed lower rates of morula and blastocyst formation when compared to uninjected controls (P<0.05). However, the developmental rates between non-starved mitochondria injection and controls were not different (P>0.05). The murine oocytes injected with serum-starved mitochondria showed lower rates of development when compared with non-starved mitochondria and controls (P<0.01). In contrast to mitochondria transfer, ooplasm transfer did not affect murine or bovine parthenogenetic development (P>0.05). The overall results showed that injection of serum-starved mitochondria influenced parthenogenetic development of both bovine and murine oocytes. Our results illustrate that the somatic mitochondria introduction accompanying nuclei has the capacity to affect reconstructed embryo development; particularly when using serum-starved cells as donor cells.