Cryogenic shipping: how it works, when to use it

Cryogenic shipping moves cryopreserved material at temperatures that dry ice cannot reach, usually at or below -150 °C, in vacuum-insulated containers cooled by liquid nitrogen (LN2). Most samples and therapies travel in dry shippers, where the nitrogen is absorbed and no free liquid remains. That one detail drives most of the dangerous goods treatment, the paperwork and the carrier conversation.

This guide explains how cryogenic shipping works from specification to return, how dry shippers compare with liquid nitrogen in transit, which rules apply and how to judge a provider. If you need the hands-on detail of conditioning a vessel or qualifying a pack, read our companion article on cryogenic transport with LN2 dry shippers.

What is cryogenic shipping?

Cryogenic shipping is the transportation of materials at very low temperatures, typically below -150 °C, using specialized containers. Cell therapies, stem cells, cell lines, tissue, embryos and other cryopreserved biological samples are the usual cargo, because their quality depends on staying frozen far below what a freezer truck or a dry ice box can hold.

What is cryogenic transportation, then? It is the same activity under another name. Cryo shipping is the short form you will hear in labs, and cryogenic logistics or cryo logistics usually means the wider job, including shipper supply, charging, routing, customs, monitoring and return of the empty vessel.

There is no single temperature that makes a shipment cryogenic in every document. Mercury's service pages use -150 °C as the typical line, Chart's MVE range describes cryogenic as -150 °C or colder, and a Bristol Myers Squibb article on cryo-shippers uses below -130 °C. So the word on a booking form is not a specification. The number has to come from the product label, protocol or study plan.

Temperature ranges in cryogenic shipping

Cold chain temperatures fall into a few working bands, and each one calls for a different coolant and a different level of handling. The table places cryogenic shipping beside the bands it is most often compared with. The first two ranges come from Mercury's cold chain page. Treat all four as planning categories, because the limit that counts is the one set for your product.

The practical lesson is that a cryogenic label can hold several numbers at once. The FDA label for Yescarta says the product is supplied in a liquid nitrogen dry shipper at or below -150 °C, while storage at the treatment center is at or below -120 °C. Shipping and storage limits can differ, so a provider should be quoting against the shipping limit. Our guide to cell and gene therapy logistics compares more product examples.

LN2 dry shippers vs liquid nitrogen

Cryogenic shipping containers split into two groups for transport purposes, depending on where the nitrogen is when the package is handed over. In a dry shipper the liquid is held in an absorbent, and the excess is poured off before dispatch. In a liquid nitrogen shipment, free liquid remains in the vessel, which changes how it can travel by air.

For most shippers, a dry shipper gives cryogenic temperatures with far less regulatory friction, so it is the normal choice for cryogenic shipments by air. Free liquid is worth accepting only when the payload or process needs it. A vessel can also change category. Chart's MVE vapor shipper manual warns that if liquid is visible in the bottom of the inner vessel, it becomes a liquid shipper and the exception status is void.

Dry shippers are not light or unlimited. The MVE Vapor Shipper series lists static holding times from 8 to 82 days by model, and notes that actual performance varies with conditions and use. The Bristol Myers Squibb authors note that shipping systems are often over 75 lb, which affects who can carry them and how they move through a site.

How does cryogenic shipping work?

Cryogenic shipping works by charging a vacuum-insulated shipper with liquid nitrogen, removing any free liquid, loading the frozen payload into the cold vapor space and moving the package on a route shorter than its usable hold time, with monitoring and a planned return. The sequence below shows who needs to do what. The exact method for each step comes from the manufacturer's manual and your procedures.

1. Set the requirement. Record the temperature limit, payload format, permitted time outside the vessel, route, receiver hours and any regulatory classification of the contents.

2. Charge the shipper. Fill it with LN2 and let the absorbent saturate. Time varies widely by model and method. Weill Cornell's dry shipper procedure notes this may take as many as 15 repetitions over 24 hours.

3. Remove free liquid. Pour off the excess and confirm none remains using the manufacturer's method. Do this in a ventilated area with cryogenic gloves and a face shield.

4. Load and link the records. Transfer the payload quickly, attach the logger and tie the vessel ID, logger ID and shipment reference together.

5. Document and hand over. Complete the air waybill wording, any payload markings and customs documents, and keep the shipper upright in its protective case.

6. Watch the journey. Track temperature, location and tilt against the plan, and act before the hold time margin is gone.

7. Receive, transfer and return. The receiver checks identity and condition, moves the payload to qualified storage and releases the vessel for return, cleaning and inspection.

Why static hold time is not transit time

A static hold time describes a stationary, upright vessel under stated conditions. Real journeys include staging, handling and possibly a pallet laid on its side. The MVE manual states that a shipper shipped on its side provides less than 40% of the specified hold time, and less than 10% if shipped upside down.

Take a hypothetical shipper with a 14-day static rating. On its side it could give under 5.6 days, and upside down under 1.4 days. A three-day international lane with a weekend customs delay can look comfortable on the data sheet and tight in practice. Plan from preparation to final transfer, then add the delay you would actually expect on that lane. These percentages apply to the models the manual covers, so ask for equivalent data on any other design.

Dangerous goods rules for cryogenic shipments

Are dry shippers dangerous goods?

A correctly prepared dry shipper is generally not treated as dangerous goods for air transport, although liquid nitrogen itself is. Special Provision A152 covers insulated packagings with refrigerated liquid nitrogen fully absorbed in a porous material. As Weill Cornell's EHS guidance summarizes it, the shipper must not allow pressure to build up, must not release liquid nitrogen in any orientation, and the air waybill must read "Not restricted, as per Special Provision A152".

The exception depends on the design and on how the vessel was actually prepared on the day. It also covers the refrigerant only. Check the wording against the IATA Dangerous Goods Regulations edition in force on your shipping date, along with airline and state variations, because operators can be stricter than the baseline.

When free liquid nitrogen is on board

Refrigerated liquid nitrogen is a listed hazardous material in the US. The 49 CFR 172.101 table gives it as UN 1977, Division 2.2, with limits of 50 kg on passenger aircraft and 500 kg on cargo aircraft. Those numbers only show that a route exists in the regulations. A carrier may still decline it, so get acceptance in writing before planning around it.

Road and air are treated differently. Under 49 CFR 173.320, cryogenic atmospheric gases in Dewar flasks and similar insulated packagings, built so that pressure will not exceed 25.3 psig, are largely excepted when moved by motor vehicle or railcar. Listed duties remain, including incident reporting and the part 172 subparts on shipping papers, marking, emergency response information and training. For aircraft, the same section points to the ICAO Technical Instructions and Packing Instruction 202. A conclusion reached for a truck move does not carry over to a flight.

The payload has its own classification

Dry shipper status says nothing about what is inside it. A dangerous goods training module on dry shippers, part of a 2015 to 2016 shippers' program, shows how this works for infectious substances. Category A material goes on a Dangerous Goods Declaration. For Category B, no declaration is needed, and the air waybill carries a description such as "Biological Substance, Category B, UN 3373, 1 dry shipper, Not restricted, as per Special Provision A152". Treat that as an illustration and confirm the current format. Our guide to Category A, Category B and exempt specimens covers the classification step.

Hazards around the package

The main hazard of nitrogen in a room or vehicle is oxygen displacement. MIT's cryogen safety handout notes that one liter of liquid nitrogen expands to about 700 liters of gas at room temperature and that oxygen-deficient atmospheres have no warning properties. Charging rooms and vehicle cargo spaces deserve a ventilation check, along with cold burn protection for anyone handling the liquid. Never seal a vessel in a way that stops venting.

Monitoring a cryo shipment

Monitoring temperature of cryo shipment legs starts with one question: what does the sensor actually measure? The logger also has to suit the job, because the probe must survive and read accurately at cryogenic temperatures. Chart's PDF logger guide, for example, mounts the logger on the lid and passes a PT100 probe rated from -200 °C to +200 °C through the cork into the upper vapor phase.

That placement gives you a useful vessel reading, but it is not the temperature of the vial or bag. Report the probe position next to the data, so a reviewer knows what the trace represents. Check for gaps too. One Cryoport logger guide notes that the unit does not record internal temperature while it is disconnected from the thermocouple, so a connection check belongs in the preparation record.

Temperature is only one signal. The Bristol Myers Squibb article lists real-time options covering geolocation, internal and external temperature, tilt, shock, vibration, light sensors for possible openings and monitor battery level. For a dry shipper, tilt can be a useful early warning, since a vessel on its side can lose hold time before the temperature trace shows any problem. Light data can help explain customs or security openings.

Decide before dispatch who watches this data and what they can do about it. Practical responses include calling the carrier to correct orientation, moving the package to a recharge point, or sending a replacement shipper. If the data arrives only after delivery, it can support a quality decision but cannot save the shipment. Our articles on real-time cold chain monitoring and FDA temperature monitoring records go deeper on alerts and record keeping.

When should you use cryogenic shipping?

Use cryogenic shipping when the product label, protocol or stability data requires temperatures that dry ice cannot provide, or when cryopreservation is what makes the supply chain workable. If the approved condition is at or below -150 °C, the decision is already made. The remaining questions concern route and packaging.

Cryopreservation can also be a planning choice. World Courier reports that one in four of the cell and gene therapy shipments in its data are now cryopreserved, because it removes shelf life limits and adds flexibility. That is a vendor's own figure, but the logic holds: fresh material often has to reach its destination within a very short window, while frozen material can wait for a manufacturing slot, a patient or a receiving lab. The change has to be supported by your own product data, since cryopreservation can affect the cells themselves.

When dry ice or 2 °C to 8 °C is enough

Cryogenic shipping is the wrong tool if the product's data supports a warmer range. Some frozen gene therapies are shipped well above cryogenic limits, as the examples in our cell and gene therapy guide show. Going colder than the specification adds cost and may harm the product or its container. The Bristol Myers Squibb authors note that primary packaging can become fragile below its glass transition temperature.

Cryogenic shipping for laboratories

Laboratory cryogenic shipping solutions depend on how often you ship. A lab sending a few cell lines a year may be best served by a rented, pre-charged shipper from a provider, while a site with regular outbound work may own vessels, charge them on site and need trained staff for that work. As a hypothetical example, a lab that ships ten vials to a collaborator twice a year has little reason to own a fleet, whereas a manufacturer shipping weekly has to think about turns, spare vessels and return logistics from day one.

Choosing cryogenic shipping companies

How do you choose a cryogenic shipping company?

Choose a cryogenic shipping company by asking it to show evidence for your exact product, temperature limit and lane, including what happens when something goes wrong. Capability pages from cryogenic shipping companies tend to sound alike, so these questions separate them more effectively than a list of services:

1. Shipper evidence. Ask which models they use, what qualification data supports your payload and lane, and how the hold time was tested. Our guide to gene therapy packaging validation explains what that evidence should cover.

2. Fleet control. Ask how each vessel is cleaned, inspected, charged and retired. The Bristol Myers Squibb authors point to tracking "turns" so overused systems leave service before they fail, and World Courier describes recording who did what and when, by staff trained on the shipper's procedures.

3. Dangerous goods handling. Ask who confirms there is no free liquid, who classifies the payload, who writes the air waybill wording and which staff hold current training.

4. Monitoring and response. Ask what the probe measures, whether tilt is captured, who sees alerts outside office hours and what they are authorized to do.

5. Handoffs and contingency. Ask who physically handles the shipper at each stage, where it can be recharged and when a cryo courier traveling with the shipment makes sense. An onboard courier with cold chain handling removes carrier handoffs on the most critical legs.

6. Quality and return. Ask how the provider's records map to your quality system, how chain of custody is recorded and who owns the return leg. For cell therapies, ask how the process lines up with ISO 21973, which sets general requirements for transporting cells for therapeutic use.

Cryogenic transportation companies are easier to compare once you have seen them work a real lane, so a test shipment is often worth more than another meeting. Send a dummy payload with the real receiver, then review the data, the paperwork and the time the return took. Cryo shipping companies that are confident in their process should welcome that.

Where Mercury fits

Mercury has been shipping since 1984 and runs cryogenic work within its specialty cold chain service. Its cryogenic shipping service for cell and gene therapies covers dewars and dry shippers, temperature monitoring throughout the journey, GPS-based chain of custody and customs guidance on permits and documentation.

Mercury's cold chain page describes live temperature and GPS data through its platform, a dedicated team assigned to each shipment around the clock, and an OK-to-Send review of regulatory and packaging requirements before a shipment leaves origin. It also lists ISO 9001:2015 and GDP certifications. A request that states the temperature limit, payload classification and lane gives the team what it needs to plan from the product's requirements.