In terms of freezing techniques, extending storage times doesn't present a problem, as modern cryogenic freezers are capable of effectively storing samples indefinitely without deterioration. The potential issue comes when you consider the storage capacity of fertility facilities. A common sight in many facilities across the country is container after container filled with important biological samples. Often, sample storage facilities will start small, using just one or two freezers - often referred to as 'Dewars' - to store a few samples. As the facility grows, more and more freezers are added until you have a makeshift cryo-room.
The storage issue is compounded by a growth in assisted reproduction over the last 20 years, driven by a number of factors; an increase in the average age of people starting a family, same-sex couples and increased success in IVF treatment to name just a few.
To quantify it, according to the Human fertilisation and embryology authority the number of IVF cycles carried out each year have more than doubled since 1992. The other key factor for freezer capacity is the number of IVF cycles that have been from frozen embryos, a number which has increased from almost zero in 1991 to nearly 30,000 a year in 2019.
When you consider this along with the extended storage limits you are potentially looking at a massive increase in the need for cryogenic freezer capacity. Fertility facilities could see requirements for their services increased many times over. Traditionally fertility providers have chosen city centre locations, quite often in listed buildings, which are often beautiful and accessible for their customers, but offer limited storage space and little to no option for expansion.
However, where more space isn't an option, there's a need to consider how can you maximise your storage density. In the cryo-room model already described, with multiple aluminium freezers you would typically store in the region of 1,000 to 2,000 samples per cubic meter. A modern automated freezer such as the MVE HEco 1500 allows you to maximise the available space, offering a sample density in the region of 40,000 samples per cubic meter, significantly increasing your capacity without the need for additional floorspace.
To prepare for future storage expansion, the next logical step for fertility facilities would be to invest in a full-size, automated cryogenic freezer. Generally available with liquid or vapour phase storage, liquid nitrogen (LN2) storage freezers such as the HEco are installed in your facility and plumbed into an LN2 supply tank outside. The LN2 is efficiently carried via a Super Insulated Vacuum Line (SIVL) into the building. External bulk storage tanks are simply filled by a professional supplier, minimising the risks associated with manual handling of liquid nitrogen for your staff.
LN2 freezers also provide additional safety features, such as temperature monitors and alarms to prevent failure and loss of samples. The slow burn-off rate of liquid nitrogen also means that in the event of a supply failure samples will remain viable for several weeks, assuming the freezer remains closed during this time.
Whilst Dewars or cryogenic containers are a cost-effective option for many facilities when starting out, with the potential increase in storage capacity looming is now the time to upgrade? Even if you still have plenty of room, it may be better to upgrade sooner rather than later. Fully automated stainless steel liquid nitrogen freezers are a secure, long-term option for cryogenic storage bringing with them a host of benefits.