Oocyte bank logistics
Introduction For an egg bank, transport is one of the critical points when it comes to preserving the viability of these cells under optimal conditions. The container and type of transport must guarantee that the vitrified oocytes reach their destination at the optimum temperature to avoid reducing the viability of the cells.
Analysing the results in the survival of donor devitrified oocytes we saw great differences in survival between Spanish and foreign centres even when the vitrified oocytes came from the same donor and from the same stimulation. The oocytes were processed and vitrified in the same conditions by the embryologists of our centre, therefore, these low survival rates led us to suspect that transport could influence the viability of the cryopreserved oocytes.
Transporting donor vitrified oocytes by air means differences with land transport within the peninsular territory, for example, that the oocytes must go in a DRY-SHIPPER container in nitrogen vapours and not in liquid nitrogen. In addition, factors such as atmospheric pressure are variables that could influence the viability of cryopreserved cells.
Objectives To demonstrate that the conditions in which vitrified oocytes are transported by air do not influence their survival; neither nitrogen vapours nor changes in atmospheric pressure interfere with the survival and/ or fertilization rates of transported oocytes.
Material and methods The oocytes were collected in our centre by ovarian puncture. An hour and a half after the puncture they were decumulated and the mature oocytes that were vitrified at 2 hours after ovarian puncture were selected according to the Kitazato protocol.
We fill a Dry-Shipper container of liquid nitrogen for 24 hours. Subsequently, excess liquid nitrogen is emptied from the container. The cryotops are introduced into the Dry-shipper by means of a system that ensures that the cold chain is not altered.
Inside the container there will be a probe that will record the temperature during the entire trip, generating a graph with the temperature record that has been made at the time of transport. The container will be sent via air mode “Lab to Lab” without going through X-rays, to any destination and will return in the same way. Once back, we will keep the cryotops in our banks waiting to be devitrified for our patients.
187 MII transported by air, were devitrified; 178 survived and 143 MII fertilized correctly. The data were compared with the devitrified oocytes in our centre during the years 2015 and 2016, which were not subjected to any type of transport. All procedures were performed by the embryologists themselves.
There were no differences in survival and fertilization rates between the oocytes that were transported by air mode “Lab to Lab” in containers “Dry-Shipper” and those that remained in our centre without being transported.
Conclusions The results obtained indicate that survival and fertilization are not inferior when we devitrify oocytes that have been transported by our system of aerial Lab to Lab. Therefore, we can conclude that the type of transport and its conditions do not affect the survival and fertilization of donor vitrified oocytes in our clinic.
The differences observed in other centres that receive oocytes in this way may be due to other factors such as handling when receiving oocytes, laboratory conditions, devitrification protocols and even the training of embryologists who perform the techniques.
Authors: C. González, E. Criado (Biologists Ovobank) Studio admitted for exhibition at ASEBIR 2017