The advent of in-vitro fertilization (IVF) in animals and humans implies an extraordinary change in the environment where the beginning of a new organism takes place. In mammals, fertilization occurs in the maternal oviduct, where there are unique conditions for guaranteeing the encounter of the gametes and the first embryo development stages. During this period a major epigenetic reprogramming takes place, which is crucial for the normal development and differentiation process of the embryo. This epigenetic reprogramming is very sensitive to changes in environmental conditions such as the ones implied in IVF, including in-vitro culture, nutrition, light, temperature, oxygen tension (Adam et al., 2004), embryo-maternal signaling, and the general absence of protection against foreign elements that could affect the stability of this process (Ventura‑Junc. et al., 2015).
Various effects associated with in-vitro embryo culture can be observed early in the period from fertilization to implantation, such as low implantation rate, disturbances in development speed, embryo quality and low trophoblast development, abnormal preimplantation epigenetic reprogramming. In addition, it has been shown that suboptimal culture media affect the percentage of implantation and the survival of embryos that could achieve implantation (Morgan et al., 2005, Gruber et al., 2011).
Nowadays, the competition between clinics is centered on the quality of the customer/patient experience, which is largely based on the positive single-birth outcome in full respect of the health of women. An increase in the success rate and a decrease in the rate of multiple births is highly demanded, as well as a decrease in the side effects of hormonal therapies. The critical steps in IVF are the culture conditions in the maturing of the egg cells, the culture conditions of the fertilized egg cells and the selection process of the growing embryos.
Another advantage is that organoids can be expanded indefinitely, cryopreserved as bio-banks and easily manipulated using techniques similar to those established for traditional 2D monolayer cultures. Finally, the fact that primary-tissue-derived organoids lack mesenchyme/stroma provides a reductionist approach for studying the tissue type of interest without confounding influences from the local microenvironment.
The progress in generating organoids that faithfully reproduce the human in-vivo tissue composition has extended organoid applications from being just a basic research tool to a translational platform with a wide range of uses. The capacity to indefinitely culture organoids, without introducing genetic variation, makes them a sound model for high-throughput preclinical screenings, designing targeted and personalized therapies, and providing a source of fully functional tissue for regenerative medicine applications (Fatehullah et al., 2016).