Abstract
Vitrification is the most common method of cryopreservation of gametes in fertility clinics due to its improved survival rates compared to slow freezing techniques. For the Open Cryotop ® vitrification device, the number of oocytes, or embryos, mounted onto a single device can vary.
In this work, a mathematical model is developed for the cooling of oocytes, or embryos, that is solved computationally, to investigate whether varying the number of samples mounted onto the Open Cryotop ® affects the cooling rates, and therefore survival rates, of vitrified samples. Several realistic spatial arrangements of oocytes/embryos are examined, determining the temperature of the system over time, which highlights the effect of spatial arrangement on the rate of cooling.
Results indicate that neither spatial arrangement nor the number of mounted oocytes, or embryos, has a large effect on cooling rates, so long as the volume of the cryoprotectant remains minimal. Under the manufacturer’s guidelines, clinical decisions regarding the number and arrangement of oocytes or embryos placed on a device can be varied, whilst maintaining rapid cooling.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
⋆ This document is the results of the research project funded by the Knowledge Economy Skills Scholarship (KESS2). KESS2 is a pan-Wales higher level skills initiative led by Bangor University on behalf of the HE sector in Wales. It is part funded by the Welsh Government’s European Social Fund (ESF) convergence programme for West Wales and the Valleys. The project is additionally funded by, and in collaboration with, the London Women’s Clinic. Authors have expressed no conflict of interest or financial affiliation with any of the commercial cryopreservation devices comparedin the study.
Email addresses: woolleyt1{at}cardiff.ac.uk (Thomas E. Woolley), swannk1{at}cardiff.ac.uk (Karl Swann), andrew.thomson{at}londonwomensclinic.com (Andrew Thompson), helen.priddle{at}londonwomensclinic.com (Helen Priddle), kosmogoniaivf{at}gmail.com (Giles Palmer), kaourik{at}cardiff.ac.uk (Katerina Kaouri)