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| image credit: Prof David Albertini |
In an extraordinary scientific feat, researchers were successful in growing human oocytes from the earliest follicular stage in the laboratory in just 20 days instead of 5 months in the body. The eggs fertility potential is unknown yet, and it remains to be seen whether they can produce healthy babies.
The study was carried out in collaboration with the Royal Infirmary Edinburgh, The Center for Human Reproduction in New York and the Royal Hospital for Sick Children in Edinburgh, and published January 2018 in Journal of molecular human reproduction.
This process of oocytes maturation in lab could find potential applications in fertility preservation of cancer patients during the chemotherapy treatments. Immature eggs recovered from patients’ ovarian tissue could be matured in the lab and stored for later fertilization without the fear of reintroducing cancer.
Professor Evelyn Telfer from School of Biological Sciences said, “Being able to fully develop human eggs in the lab could widen the scope of available fertility treatments. We are now working on optimizing the conditions that support egg development in this way and studying how healthy they are. We also hope to find out, subject to regulatory approval, whether they can be fertilized.”
Till now researchers have successfully produced live offspring in mouse from in vitro grown (IVG) oocytes from primordial follicles. They have also grown human oocytes from secondary/multi-laminar stage to obtain fully grown oocytes capable of meiotic maturation.
However, this is the first report of in vitro complete human oocyte growth from immature primordial/unilaminar follicles using two-step culture system.
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| A series of magnified images show human eggs in development stages. Prof. Evelyn Telfer and Dr. Marie McLaughlin/University of Edinburgh/Handout via REUTERS |
The scientist obtained fresh ovarian cortical pieces of approximate size 5 mm × 4 mm from women undergoing elective cesarean section. Fragments were cultured for 8 days according to the institute predetermined protocols.
Follicles ranging in diameter from 100–150 μm were dissected for further isolated culture. After about 8 days cumulus-oocyte complexes (COCs) were retrieved by gentle pressure on the cultured follicles. These COCs were further cultured for 4 more days when complexes containing oocytes >100 μm diameter were selected for in vitro maturation (IVM) in SAGE medium and subsequently fixed for analysis.
Confocal immuno-histochemical analysis of oocytes more than 100 μm diameter showed the presence of a Metaphase II spindle confirming that these IVG oocytes had resumed meiosis but their developmental potential is unknown.
Other scientists are looking at this process with great concern because of the shortened maturation process and lack of genetic analysis of the matured egg.
Telfer agrees that much work needed to be done and said, “We had no great expectations. To see at least one [egg reaching maturity], we thought, ‘Wow, that’s actually quite incredible.’”
The eggs fertility potential is unknown yet because of lack of regulatory approval, and even if they have can be fertilized much research is needed to see whether they can produce healthy babies.
But, the study has given new insights on human egg development that could be very useful in fertility treatment and regenerative therapies.
Her team is working on improving the process and getting an approval from the United Kingdom’s Human Fertilization and Embryology Authority—to try fertilizing the lab-matured eggs to create human embryos.
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