In the past decade we’ve experienced a tremendous amount of growth in the development of biologics and cell-based therapeutics. While these therapies often demonstrate superior efficacy over current products—or even treat a disorder that currently has no cure—I have seen their clinical and commercial development delayed for lack of the right cold chain environment.
Two of the many cold chain-related challenges faced by companies developing autologous cell-based therapies are 1) the need for immediate processing of patient cells, and 2) the expense of freezing patient cells at cryogenic temperatures to preserve their viability. In my white paper, I’ve described a solution we devised and tested that solved two of these problems at the same time: a custom-designed shipper that freezes cells at a controlled rate, from ambient to -196°C, within three hours, as the cells are en route to the client’s laboratory.
Patient cells that are isolated for development into a therapeutic product must be processed quickly or they lose their integrity and therapeutic value. Cells that cannot be processed immediately must be cryopreserved at -195°C in liquid nitrogen. However, to ensure viability and integrity upon thawing, freezing down to -195°C must be performed at a specific cooling rate, which requires equipment that exceeds the financial resources of most clinical sites.
Fisher BioServices presents an inexpensive and innovative solution that allows staff at any clinical site to draw and process patient blood and place the resulting peripheral blood mononuclear cells (PBMCs) in a specialized shipper that will freeze the cells to -195°C. This solution utilizes a novel device and configuration that is capable of cooling at a rate between 0.5°C and 2.0°C per minute, reaching –195°C over a span of three hours as the cells are in transit to a laboratory or biorepository storage facility.
Introduction: The Problem
Cell-based therapies, regenerative medicine, vaccines, and other biological materials frequently require processing and administration to the patient within an extremely short timeline (24 hours). The alternative is to preserve the cells at cryogenic temperatures (below -150°C) to maintain their live properties until the appropriate time. Ideally, cells and living organisms are preserved in liquid nitrogen (LN2), at -196°C, at which temperature all biochemical activity ceases.
The cryopreservation of cells must be performed in a specific manner in order to recover the critical properties of those cells upon thawing. This involves use of a well-defined cryoprotective medium to prevent crystallization and destruction of cells during the freezing process, and a cooling rate of between -0.5°C and -2.0°C per minute (with a target cooling rate of -1.0°C per minute) to prevent temperature shock. This controlled rate, combined with the protective medium, leads to optimal viability of the cells upon thawing.
How Much Does it Cost?
Cryopreservation is a costly process. Controlled-rate freezing equipment is expensive and requires a source of LN2 as coolant. An LN2 tank is also needed for storage of the materials once they are frozen. Few clinical sites, where patient samples are drawn, have the equipment needed to freeze patient cells directly to cryogenic temperatures.
The current, less costly alternative to controlled-rate freezing units are the passive containers that provide insulation and controlled cooling within a -80°C ultra-low mechanical freezer. The vials are placed in the container, which is then placed in the ultra-low freezer for about 16 hours, until the cells reach -80°C. These devices (such as the Mr. Frosty® container, manufactured by Thermo Scientific Nalgene™ and the CoolCell® device manufactured by BioCision) are widely used, accepted in the research community, and are economical. However, these devices require access to an expensive mechanical -80°C freezer.
What About Shipping?
The pharmaceutical industry primarily uses dry ice to ship frozen materials; dry ice sublimes from solid to CO2 gas phase while maintaining a local temperature of approximately -80°C. As a result, the International Air Transportation Association (IATA) classifies dry ice as dangerous goods. In addition, the amount of dry ice needed to maintain temperature results in bulky and heavy packaging, contributing to higher transportation costs. Further, the rate at which dry ice sublimes allows maintenance of -80°C for only a few days.
In contrast, liquid nitrogen dry shippers will preserve materials at the optimal temperature of -196°C during transit, and can maintain that temperature for more than two weeks. Another advantage is that LN2 (a Class 2.2 non-flammable gas and cryogenic liquid under regulation UN1977) is exempted and not considered dangerous by the IATA when it is fully absorbed in a porous material and intended for transport (See IATA Special Provision A152 below).
Special Provision A152, from IATA Column M of the List of Dangerous Goods Section 4.4
“Insulated packagings conforming to the requirements of Packing Instruction 202 containing refrigerated liquid nitrogen fully absorbed in a porous material are not subject to these Regulations provided the design of the insulated packaging would not allow the build-up of pressure within the container and would not permit the release of any refrigerated liquid nitrogen irrespective of the orientation of the insulated packaging and any outer packaging or overpack used is closed in a way that will not allow the build-up of pressure within that packaging or overpack”.
“When used to contain substances not subject to these Regulations the words “Not Restricted” and the Special Provision number must be included in the description of the substance on the Air Waybill as required by 8.2.6, when an Air Waybill is issued”
We proposed a freeze-and-ship technology that would not require costly investments at the investigating site and would provide immediate cryogenic freezing of the cellular material during transfer to the destination laboratory or biobank. To develop an acceptable solution, step-down freezing and concurrent shipping must provide optimal preservation of patient cell integrity and post-thaw viability for downstream processing and administration. This technology had to be affordable, verified to produce a cooling rate of -1°C per minute, and be compatible with ultra cold chain logistics.
We developed numerous prototypes to determine the thermal resistance/conductivity criteria required for the insulation material. Multiple experiments using different probe locations were run, to determine the cooling rate relative to their location in the foam. Download the whitepaper to read about the entire study.
Download White Paper:Controlled-Rate Freezing of Cells During Ultra Cold Transit