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Planning Next-Gen Biological Repositories Cheat Sheet (DRAFT) by [deleted]

How to Plan Next-generation Biological Repositories

This is a draft cheat sheet. It is a work in progress and is not finished yet.


Today, there are more than 300 million biological samples in the world stored at temper­atures below -80 C. Few of these samples have a storage strategy associated with them. A recent U.S. National Institutes of Health (NIH) discussion group estimated that up to 70 percent of all the sample material stored at -80 C and below is unusable because of its lack of proven­ance. In other words, these samples do not have histories, they can’t be traced, their origins are unknown, and enviro­nmental storage records don’t exist.

Effective planning will produce two important benefits for your sample library. The first is sample value and viability. If an organi­zation doesn’t develop a long-term storage plan, then 90 percent of the time the potential use of the material will be compro­mised.

The second benefit is cost reduction. Unless there is thought about the reasons behind sample storage, a lot of money can go to waste. Strategic planning results in creating a cold space that fits a purpose, and then controls its use in a way that provides maximum efficiency and minimal operating expense.

Explore the five critical elements in planning next-g­ene­ration biologic reposi­tories, their implic­ations on storage conditions in the preser­vation protocol, and their benefits for an organi­zation

Five Key Elements

There are two types of cryogenic storage. The first is transa­ctional storage. This covers material that typically will be used for 3 to 12 months. It could include a collection that a researcher may want to repurpose, such as genetic inform­ation. If an individual is managing a drug discovery project, he or she may have cryopr­ese­rvation systems to store material that is used again and again. That’s known as transa­ctional storag­e—there is a transa­ctional reason to manage samples for a given period of time.

For long-term storage, which is referred to as archival storage, the decisions are completely different. There are five key elements that must be addressed when planning archival cold space.

1. Storage objective

Why are the samples being stored? At first glance, that might appear to be a stupid question. The reason behind sample storage is important however, because one never really knows the true potential value of the material. The effort required to store the samples in a way that is regulated, tracked (with the correct inform­ation), and creates provenance represents very little additional effort compared to the generation of the samples in the first place. That little bit of effort is what instills all of the value in an organi­zat­ion’s research material.

In addition, an organi­zation needs to know how many samples it wants to store. One caveat: no one ever throws anything away. Take the number of samples planned for storage and triple it.

2. Biological viability

The reasons for storing biological material can vary widely and will play a major role in developing a sound sample management strategy. There are serious implic­ations for the usability of the material associated with the temper­ature at which it is stored.

Therefore, part of the planning process must be to understand the implic­ations of the storage strategy on long-term cell viability. How long will the samples be stored? In the vast majority of cases, this question is never asked. If the samples must thrive when removed from a cold enviro­nment, the storage temper­ature will have a profound effect on how long the material can be kept: -135 C is considered the normal transition point for cryogenic storage media. All of the research demons­trates that if the samples have been prepared properly, and stored below -135 C, it is possible to keep the material infinitely and still have biofun­ction when removed.

Once the storage temper­ature rises above -135 C, however, this is no longer the case. At that point, it is a question of how long the material can be archived before it degrades. So it is important to know what temper­ature is approp­riate for the lifetimes of the samples. That modality choice must be driven by whether the samples are being stored for transa­ctional or archival purposes.

An organi­zation must also decide what it is going to store, and know what it is going to store it in. It doesn’t matter what type of biocry­ogenic storage is being consid­ered—an under-­bench refrig­erator, a biostore that holds two million samples or a liquid nitrogen dewar. Unless these questions can be answered, chances are an organi­zation will not create the right enviro­nment for said material.

3. Thermal perfor­mance

When an organi­zation begins to develop these strate­gies, the creation and management of the storage systems are key issues. One thing worth rememb­ering when creating cold space is that the real investment is in insula­tion. The method by which heat energy is removed is almost irrele­vant. For example, the reason a liquid nitrogen storage dewar is so much more efficient than an -80 C mechanical freezer has nothing to do with the fact that one uses liquid nitrogen and the other uses a mechanical compre­ssor. Instead, it is because one has 100x better insulation than the other.

For example, if you compared a Vario liquid nitrog­en-­based storage system to a mechan­ically cooled storage box, the difference in thermal perfor­mance would have little to do with the systems’ cooling techno­logies. The difference between the two boxes is that one has 3 inches of expanded polyur­ethane foam and the other has a sub-5-­micron vacuum system with super insula­tion. The amount of heat energy that gets into the Vario’s space is less than the energy that will penetrate the mechanical box. Any cold space, no matter how it is powered or cooled or sized, will increase its thermal perfor­mance and efficiency most effect­ively by improving the insula­tion.

4. Enviro­nmental impact

The enviro­nmental impact of a large biological repository can be substa­ntial due to its cooling requir­ements and energy consum­ption. For example, three -80 C freezers have the same enviro­nmental footprint as a typical family car. Five freezers have the same impact as a domestic dwelling’s annual power consum­ption. Insulation can make a dramatic difference in enviro­nmental impact. If the cooling capacity shuts off in an ultra-high efficiency cold space, the temper­ature will be maintained for about one week. In a mechan­ically cooled box, the temper­ature will start to rise in about one hour after cooling stops. Organi­zations that value enviro­nmental sustai­nab­ility must consider energy efficiency and insulation types when planning their sample storage and management systems.

5. Cost

When evaluating cost, it is important to consider holistic cost, or the total cost of ownership. Typically, when a lab runs out of -80 C storage space, it buys another $10,000 freezer and plugs it into the wall. The lab may not consider the cost of electr­icity because it gets paid from a different budget. The organi­zation also must pay for the air condit­ioning that removes the excess heat generated by the freezer. There are also costs associated with mainte­nance and repairs. All of these expenses should be considered when planning a sample storage strategy.