Quality of cord blood cryopreserved for up to 5 years

Total nucleated cell counts are driving clinician's choice rather than cryopreservation period: Lesson for cord blood banks

According to the increase in both the number of cryopreserved cord blood (CB) units and the cryopreservation period for each CB unit in the largest public CB bank in Korea, we are pursuing greater efficiency in CB bank management. Thus, we analyzed whether the cryopreservation period has a negative impact on the selection of CB units for CB transplantation (CBT). Until December 2019, 468 CB units were used for transplantation. The cryopreservation period, total nucleated cell (TNC), and CD34+ cell counts were analyzed among the CB units according to the CBT-year and the donation year. The results showed that the cryopreservation period was increased in recent CBT-year groups. The transplanted CB units showed similar TNC counts irrespective of the donation year, and the mean TNC count was 13.9 × 108/unit. CB units cryopreserved for a relatively long period were transplanted consistently. The mean TNC count of CB units cryopreserved for over 10 years was 16.4 × 108/unit. The mean CD34+ cell counts were not significantly different among the CB units transplanted after CBT-2013 and among the CB units donated after CBT-2011. Through an analysis of the CB units selected by clinicians for CBT, this study revealed that clinicians placed more weight on the TNC counts than on the cryopreservation period of cryopreserved CB units. Therefore, the minimum TNC count of CB units suitable for cryopreservation should be increased up to 13.0 × 108/unit to balance the satisfaction of clinicians' needs with the efficiency of the CB bank.

Cryopreservation of Hematopoietic Stem Cells: Emerging Assays, Cryoprotectant Agents, and Technology to Improve Outcomes

Hematopoietic stem cell (HSC) therapy is widely used to treat a growing number of hematological and non-hematological diseases. Cryopreservation of HSCs allows for cells to be transported from the site of processing to the site of clinical use, creates a larger window of time in which cells can be administered to patients, and allows sufficient time for quality control and regulatory testing. Currently, HSCs and other cell therapies conform to the same cryopreservation techniques as cells used for research purposes: cells are cryopreserved in dimethyl sulfoxide (DMSO) at a slow cooling rate. As a result, HSC therapy can result in numerous adverse symptoms in patients due to the infusion of DMSO. Efforts are being made to improve the cryopreservation of HSCs for clinical use. This review discusses advances in the cryopreservation of HSCs from 2007 to the present. The preclinical development of new cryoprotectants and new technology to eliminate cryoprotectants after thawing are discussed in detail. Additional cryopreservation considerations are included, such as cooling rate, storage temperature, and cell concentration. Preclinical cell assessment and quality control are discussed, as well as clinical studies from the past decade that focus on new cryopreservation protocols to improve patient outcomes.

Flow Cytometric Aldehyde Dehydrogenase Assay Enables a Fast and Accurate Human Umbilical Cord Blood Hematopoietic Stem Cell Assessment

Objective:

Colony-forming units of granulocytes/macrophages (CFU-GM) analysis is the most widely used method to determine the hematopoietic stem cell (HSC) content of human umbilical cord blood (CB) for prediction of engraftment potential. The measurement of aldehyde dehydrogenase (ALDH) activity is a more recent method for HSC qualification. Our aim was to correlate phenotypic and functional assays to find the most predictive method.

Materials and Methods:

In this study, flow cytometric quantitation of CD34⁺ cells and ALDH positivity along with CFU-GM capacity were assessed in fresh and post-thaw CB units.

Results:

Among 30 post-processing samples, for each CB unit the mean total number of nucleated cells (TNCs) was (93.8±30.1)x10⁷, CD34⁺ cells were (3.85±2.55)x10⁶, ALDH⁺ cells were (3.14±2.55)x10⁶, and CFU-GM count was (2.64±1.96)x10⁵. Among an additional 19 post-thaw samples the cell counts were as follows: TNCs, (32.79±17.27)x10⁷; CD34⁺, (2.18±3.17)x10⁶; ALDH⁺, (2.01±2.81)x10⁶; CFU-GM, (0.74±0.92)x10⁵. Our findings showed that in fresh samples TNCs, CD34⁺ cells, and ALDH correlated highly with counts of CFU-GM, CFU-erythroids/granulocytes-macrophages/megakaryocytic cells (GEMM), and burst forming units of erythroids (BFU-E) as follows: TNCs, r=0.47, r=0.35, r=0.41; CD34+, r=0.44, r=0.54, r=0.41; and ALDH, r=0.63, r=0.45, r=0.6, respectively. In terms of post-thaw samples, the correlations were as follows: TNCs, r=0.59, r=0.46, r=0.56; CD34⁺, r=0.67, r=0.48, r=0.61; and ALDH, r=0.61, r=0.67, r=0.67, for CFU-GM, CFU-GEMM, and BFU-E, respectively. All correlations were statistically significant.

Conclusion:

In our experience, HSC assessment by ALDH activity yields the highest correlation with conventional analytical methods, particularly for post-thaw samples. Thus, this fast, inexpensive method has the potential to overcome the weaknesses of other techniques.

Long-Term Quality Control Program Plan for Cord Blood Banks in Korea: A Pilot Study for Cryopreservation Stability

Background

Maintaining the quality of cryopreserved cord blood is crucial. In this pilot study, we describe the results of the internal quality control program for a cord blood bank thus far.

Methods

Donated cord blood units unsuitable for transplantation were selected for internal quality control once a month. One unit of cord blood, aliquoted into 21 capillaries, was cryopreserved and thawed annually to analyze the total nucleated cell count, CD34⁺ cell count, cell viability test, and colony-forming units assay.

Results

No significant differences in the variables (total nucleated cell count, cell viability, CD34⁺ cell count) were observed between samples cryopreserved for one and two years. Upon comparing the variables before cryopreservation and post thawing with the capillaries of one year of storage, cell viability and CD34⁺ cell counts decreased significantly. The use of cord blood samples in capillaries, which can be easily stored for a long period, was similar to the methods used for testing segments attached to the cord blood unit.

Conclusions

The results of this study may be useful for determining the period during which the quality of cryopreserved cord blood units used for transplantation is maintained.

[Impact of cryopreservation duration of 605 units umbilical cord blood on quality of hematopoietic stem cell and outcome of clinical transplantation]

OBJECTIVE

To investigate the impact of cryopreservation duration of umbilical cord blood (UCB) on quality of hematopoietic stem cell and outcome of clinical transplantation.

METHODS

605 units of UCB which had been used in clinical transplantation were previously cryopreserved for 820 (88-2651) days in average. UCB was detected for total nucleated cell count, CD34+ cells count, cell recovery rate, cell viability and CFU-GM after thawing.

RESULTS

No statistical correlation was found between cryopreservation duration and cell recovery rate, cell viability. CFU-GM decreased along with the extension of cryopreservation duration (P=0.011), ranging between 109.6 and 105.7/1 × 10⁵. There was no significant difference on hematopoietic reconstitution time, graft failure, acute GVHD and overall survival among groups with different cryopreservation duration.

CONCLUSION

Cryopreservation duration has no significant effect on cell recovery rate, cell viability and clinical transplantation outcome. Extension of cryopreservation duration may reduce CFU-GM of stem cells with fluctaion still in normal range. UCB could maintain cell viability and function to achieve satisfactory clinical transplantation outcome even when thawed after 3 to 7 years' cryopreservation.

Umbilical cord blood CD34(+) stem cells and other mononuclear cell subtypes processed up to 96 h from collection and stored at room temperature maintain a satisfactory functionality for cell therapy

BACKGROUND AND OBJECTIVES

Umbilical cord blood (UCB) is a good stem cell source for cell therapy. We recently demonstrated that cord blood mononuclear cell (MNCs) subtypes were viable and functional until 96 h after collection, even stored at room temperature. Now, we analyzed the viability and functionality of the cells before and after cryopreservation.

MATERIALS AND METHODS

Twenty UCB units were analyzed at 24 and 96 h after collection, frozen for 6 months, thawed and re-evaluated. MNCs were analyzed by flow cytometry, viability by 7-AAD and clonogenic assays (CFU) were performed.

RESULTS

After 96 h of storage, no substantial loss of MNC was found (median 7.320 × 10(6 ) × 6.05 × 10(6) ). Percentage and viability CD34(+) cells, B-cell precursors and mesenchymal stem cells were not affected. However, mature B and T lymphocytes as well as granulocytes had a substantial loss. CFU growth was observed in all samples. Prefreezing storage of 96 h was associated with a relative loss of colony formation (median 12%). Postthaw, this loss had a median of 49% (24 h samples) to 56% (96 h samples).

CONCLUSION

The delay of 96 h before UCB processing is possible, without a prohibitive impairment of CD34(+) loss in number and functionality.