Biopsy Snap Frozen within Seconds

The standard procedure for rapid freezing a biopsy taken from a patient involves the use of liquid nitrogen. Such a procedure, however, is not allowed inside operating rooms, thus causing frequent challenges and delays. But researchers at the Netherlands’ University of Twente have now developed a “snap freezing” apparatus that is safe for use inside the operating room and cools a vial even faster than liquid nitrogen.

For many current laboratory tests, a biopsy is kept at room temperature all the way from taking the tissue sample to the lab. But for protein analysis, proteomics, the tissue has to be instantly frozen.

This is also called snap freezing and is made possible by immersing a vial containing the tissue in a bath of liquid nitrogen, cooling it down to -196°C. To avoid risks for the patient and medical staff, the process cannot be done inside the operation room. And in practice, someone is waiting directly outside with a liquid nitrogen container, wearing protecting clothing.

But there is still a delay in moving the sample outside, a procedure that may influence the lab results. The new snap freezer, developed by UT scientists, can simply be connected and does not have any risk of physical contact or doctors breathing harmful cooling gas or liquid. Special gloves or clothing aren’t necessary either, and the apparatus freezes vials even faster than in liquid nitrogen, reaching -173°C within 10 seconds.

The device consists of a compact cryocooler, a buffer made of copper for retaining the low temperature (thermal energy storage unit, TESU) and a closed helium gas system that works as a heat exchanger. There is a gap between the TESU and the vial with the biopsy for contact gas flow.

Researchers expected to see cooling by the movement of the gas—much like windchill making us feel colder than the actual temperature—but, surprisingly, this effect has not been demonstrated. Apart from developing a new device, the research also gives new physical insights in gas flows.

The research project, called CryoON–Cryogenics meets Oncology, is led by dr. Srinivas Vanapalli, and is part of the university’s Energy, Materials and Systems group led by Professor Marcel ter Brake, who has extensive experience with superconductivity and the development of coolers for a wide range of applications. The project was made possible by the NWO-TTW, the applied and technical sciences section of the Netherlands Organization for Scientific Research.

The medical center of the Free University in Amsterdam (VUmc) is also testing the device by working on a sustainable solution for cold transport, for example when a tissue sample has to be moved over a large distance to another lab. Except for diagnostics, rapid cooling devices are also promising in treatment, killing tumor cells in a highly targeted way. This is currently another field of research being addressed together with cryoablation specialists.