Background: Peripheral blood mononuclear cells (PBMCs) count among the most important samples in a biobank, and the quality of cryopreserved PBMCs is crucial for further research. This study evaluated the quality of PBMCs recovered from the Beijing Capital Medical University Hepatitis/AIDS Biobank after 2-11 years of cryopreservation. Materials and Methods: A total of 87 PBMC samples with different cryopreservation times (2006, 2007, 2013, and 2015) were thawed, and the cell number and cell viability were determined by acridine orange/propidium iodide staining. Then, DNA was extracted from the cryopreserved PBMCs and assessed for quantity on an ultramicrospectrophotometer. Results: The median cell viability rate was 73.58% for the 87 PBMC samples cryopreserved for 2-11 years. A rate of 80.98% was obtained for PBMCs collected in 2006, a value higher than those of other cryopreservation times (2007, 2013, and 2015). Similarly, more live and total cells were obtained in PBMCs cryopreserved since 2006 compared with other cryopreservation times (since 2007, 2013, and 2015, respectively). Nonparametric Spearman correlation analysis indicated positive associations of cell viability with live (r = 0.578, p < 0.0001) and total (r = 0.338, p = 0.0003) cell numbers. Meanwhile, DNA amounts increased with total cell number. Statistical analysis showed that 3.69 μg DNA was obtained from ∼1 × 106 cells. Conclusion: Cryopreservation time (2-11 years) has negligible effects on the quality of PBMCs. Meanwhile, the cell number is positively correlated with cell viability.
Keywords: PBMC; biobank; recovery; viability.