Study on Cryopreservation of Peripheral Blood Mononuclear Cells by Ultrasonic Ice Seeding

Peripheral blood mononuclear cells (PBMCs) are important immune cells. However, traditional slow-freezing methods delay the proliferation of PBMCs and damage T-cell subsets. Therefore, there is an urgent need to develop an alternative cooling procedure that can effectively preserve the viability and function of PBMCs. In this study, we optimized the cryopreservation of PBMCs using ultrasonic ice seeding and analyzed post-cryopreservation T-cell subtypes using flow cytometry. An ultrasonic ice-seeding apparatus was constructed to achieve contactless ice seeding by combining an ultrasonic generating device and a controlled-rate freezer. The results showed that the cooling procedure involving ultrasonic ice seeding exhibited superior efficacy compared to the conventional slow-freezing approach. Following cryopreservation, the viability and cumulative proliferation of PBMCs were 94.97% and 204.47%, respectively. The proportion of naive T cells (Tn) after cryopreservation and thawing accounted for up to 18.35%. By incorporating ultrasonic ice seeding, the optimized cryopreservation procedure enhanced the post-thaw viability, cumulative proliferative capacity, and proportion of T-cell subtypes in PBMCs, providing a novel and effective approach for PBMC cryopreservation.