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. 2023 Aug 7;10(8):934.
doi: 10.3390/bioengineering10080934.

Isochoric Supercooling Organ Preservation System

Gabriel Năstase  1 , Florin Botea  2   3 , George-Andrei Beșchea  1 , Ștefan-Ioan Câmpean  1 , Alexandru Barcu  2 , Ion Neacșu  4 , Vlad Herlea  2 , Irinel Popescu  2   3 , Tammy T Chang  5 , Boris Rubinsky  6 , Alexandru Șerban  7
Affiliations

Isochoric Supercooling Organ Preservation System

Gabriel Năstase et al. Bioengineering (Basel). .

Abstract

This technical paper introduces a novel organ preservation system based on isochoric (constant volume) supercooling. The system is designed to enhance the stability of the metastable supercooling state, offering potential long-term preservation of large biological organs at subfreezing temperatures without the need for cryoprotectant additives. Detailed technical designs and usage protocols are provided for researchers interested in exploring this field. The paper also presents a control system based on the thermodynamics of isochoric freezing, utilizing pressure monitoring for process control. Sham experiments were performed using whole pig liver sourced from a local food supplier to evaluate the system's ability to sustain supercooling without ice nucleation for extended periods. The results demonstrated sustained supercooling without ice nucleation in pig liver tissue for 24 and 48 h. These findings suggest the potential of this technology for large-volume, cryoprotectant-free organ preservation with real-time control over the preservation process. The simplicity of the isochoric supercooling device and the design details provided in the paper are expected to serve as encouragement for other researchers in the field to pursue further research on isochoric supercooling. However, final evidence that these preserved organs can be successfully transplanted is still lacking.

Keywords: cryopreservation; isochoric system; large organ preservation; liver; porcine/pig model; subfreezing temperatures; supercooling.

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Conflict of interest statement

B.R. and C.N. are inventors in a patent application in the field of isochoric preservation held by UC Berkley. A.Ș., C.N. and B.R. are co-inventors in a patent in the field of isochoric preservation issued to University Politehnica of Bucharest, Faculty of Mechanical Engineering and Mechatronics. The sponsors had no role in the design, execution, interpretation, or writing of the study.

Figures

Figure 1
Figure 1
Schematic of isochoric (constant volume) freezing. (A) schematic of the process of freezing in an isochoric chamber. (B) The process of freezing in an isochoric system and an isobaric system depicted on an ice water phase diagram (C) percentage of ice in an isochoric system as a function of temperature.
Figure 2
Figure 2
The schematic illustrates the isochoric supercooling system, which comprises a sealed “isochoric chamber” filled with isochoric chamber fluid. The chamber provides space for storing multiple organs or biological tissues, enclosed in thin plastic hydrophobic bags. These bags facilitate heat and pressure transfer but prevent mass transfer. The pressure inside the isochoric chamber is monitored by a pressure transducer, while temperature sensors keep track of the isochoric chamber fluid’s temperature. The isochoric chamber is immersed in a “cooling bath” containing a cooling bath fluid, which maintains the desired preservation temperature. A temperature transducer, submerged in the cooling bath fluid, measures the temperature of the bath fluid.
Figure 3
Figure 3
Top (A) and side view (B) of the open isochoric chamber.
Figure 4
Figure 4
(A) View of the isochoric chamber lid from the bottom. (B) View of the isochoric chamber lid from the top. O—overflow port, T—thermal transducers, P—pressure transducer, F—filling port.
Figure 5
Figure 5
(A) Assembled isochoric chamber, (B) assembled lid. O—overflow port, T—thermal transducers, P—pressure transducer, F—filling port, V shut-off valve.
Figure 6
Figure 6
(A) Isochoric chamber cooling bath. (B) Isochoric chamber immersed in the cooling bath fluid.
Figure 7
Figure 7
The evaporator chamber in which the isochoric chamber cooling bath fluid is cooled by the evaporator of a homemade compression refrigeration system.
Figure 8
Figure 8
Schematic of all the components of the isochoric supercooling refrigerator. The highlighted “hydraulic circuits” elements are controlled by the control system. Pump Pr recirculates the cooling fluid in the evaporator’s cooling bath to eliminate stratification; pump Pc circulates the cooling fluid between the evaporator’s cooling bath and the isochoric chamber’s cooling bath or recirculates the fluid in the isochoric chamber’s bath; the 3-way directional control solenoid valve, M, is diverting the fluid between two different directions.
Figure 9
Figure 9
The electrical and automation panel.
Figure 10
Figure 10
Pressure in an isochoric chamber filled with water as a function of time after the start of the experiment. Temperature control began when the pressure reached 0.2 MPa.
Figure 11
Figure 11
(A) The pig liver inside the 2 L LDPE plastic bag in the isochoric chamber filled with 3M NaCl. (B) The liver in the sealed plastic bag.
Figure 12
Figure 12
The temperature inside the cooling bath and the isochoric chamber during a 48 h isochoric supercooling experiment.
Figure 13
Figure 13
The pressure trace inside the isochoric chamber during the supercooling experiment.
See this image and copyright information in PMC

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