The advent of artificial tissues, cord blood therapies, cell transplantation procedures, and the desire to bank germ (egg/sperm) cells have driven the need to establish a means to reliably store biological materials. Cryopreservation is an effective means to store biological materials without functional degradation over a prolonged period of time. The primary cryopreservation challenge is to lower the temperature of biological materials without destroying the cells through dehydration or excessive ice crystal formation. Currently, experiments are heavily utilized in order to establish optimum cryopreservation cooling procedures. The cost, time, and lack of certain biological materials (such as human egg cells) required to experimentally develop cooling procedures are driving the development of mathematical models to predict thermal-hydraulic behavior upon cooling. The outcome of this project is a tool that will provide thermal property information of single cells that can be used in such models.
With respect to the intellectual merit of this project, the micro-differential scanning calorimeter (microDSC) to be developed will be at least 100 times more sensitive than currently available differential scanning calorimeters. The heightened sensitivity will allow the intracellular phase change temperature to be measured directly. It is hypothesized that using the actual intracellular phase change temperature, as opposed to assuming the intracellular fluid to have the same phase change temperature as the extracellular solution, will improve the predictive capabilities of the models.
As for the broader impacts, the fully functional microDSC and cryopreservation model improvements that will be developed will relieve cryobiologists of the large number of experiments needed to obtain an optimum cooling procedure. The number of cell and tissue types that can be effectively cryopreserved will be accelerated as the mathematical models will be capable of predicting successful cryopreservation procedures.
In addition to improving the predictive capability of the cryopreservation models, it is expected that the microDSC will allow studies of ice crystal formation within cell scale samples by modifying the control algorithm. The tool will utilize thermoelectric elements that can provide a prescribed amount heating or cooling to the sample based on the magnitude and polarity of the applied electric current. Investigations of other biological phase changes applications where precise temperature control is required, such as configuration changes in proteins, could be possible with this tool as well. Insights into the intracellular structure will also be possible. Finally, it is expected that understanding the phase change phenomena of individual cells will allow more accurate models of cell masses, such as organs, to be developed. Those improved organ models will improve our current ability to prolong the viable life of organs for transplant.
