Cryopreservation by vitrification has been widely used in Assisted Reproductive Technology (ART) to preserve embryos for an extended period of time. However, the effect of vitrification on development of the embryos is lacking. Therefore, understanding on vitrification effects on embryonic proteins, especially those involved in preimplantation development is crucial to provide high quality embryos for further usage. In this study, XIAP and S6K1 protein expressions following vitrification was investigated, since they have been implicated in diverse cellular processes including cell growth, migration, proliferation, differentiation, survival and development of preimplantation embryos via the PI3K pathway. Embryos were obtained from superovulated female ICR mice which were mated with fertile males. The embryos were harvested at the 2-cell stage and cultured until blastocyst stage. Blastocysts were then vitrified in ESF40 cryoprotectant. Western blot was carried out to determine the expression of XIAP and S6K1 proteins. The results showed the expression of XIAP and S6K1 significantly decreased in vitrified blastocyst compared to the control. This indicates that blastocyst vitrification may impact developmental competence through the activation of apoptotic pathways.
This review summarizes the impact of tocotrienols (TCTs) as antioxidants in minimizing
oxidative stress (OS), particularly in embryos exposed to OS causing agents. OS level is
increased, for example, by nicotine, a major alkaloid content in cigarette, which is also a source
of exogenous reactive oxygen species (ROS). Increased nicotine-induced OS increases cell
stress response, which is a common trigger leading to embryonic cell death. Having more
profound anti-oxidative stress effects than its counterpart tocopherol, TCTs improve blastocyst
implantation, foetal growth, pregnancy outcome and survival of the neonates affected by
nicotine. In reversing cell developmental arrest caused by nicotine-induced OS, TCTs enhances
PDK-1 expression in the P13K/Akt pathway and permit embryonic development beyond the 4-
cell stage with the production of more morulae. At the cytoskeletal level, TCTs increase the
number of nicotine-induced apoptotic cells, through caspase 8 activation in the mitochondria.
TCTs facilitate rough endoplasmic reticulum (rER) stress-mediated apoptosis and autophagy,
resulting from nicotine-induced OS. Reduced vesicular population in TCT supplemented
oocytes on the other hand may suggest reduced secretion of apoptotic cell bodies thus probably
minimizing vesicular apoptosis during oocyte maturation. Further extensive research is
required to develop TCTs as a tool in specific therapeutic approaches to overcome the
detrimental effects of OS.
Human pluripotent stem cells (hPSCs) derived from either blastocyst stage embryos (hESCs) or reprogrammed somatic cells (iPSCs) can provide an abundant source of human neuronal lineages that were previously sourced from human cadavers, abortuses, and discarded surgical waste. In addition to the well-known potential therapeutic application of these cells in regenerative medicine, these are also various promising nontherapeutic applications in toxicological and pharmacological screening of neuroactive compounds, as well as for in vitro modeling of neurodegenerative and neurodevelopmental disorders. Compared to alternative research models based on laboratory animals and immortalized cancer-derived human neural cell lines, neuronal cells differentiated from hPSCs possess the advantages of species specificity together with genetic and physiological normality, which could more closely recapitulate in vivo conditions within the human central nervous system. This review critically examines the various potential nontherapeutic applications of hPSC-derived neuronal lineages and gives a brief overview of differentiation protocols utilized to generate these cells from hESCs and iPSCs.