(P-BT-24) Quantification of CD34, NK and mononuclear cells in 1272 cord blood samples

Background/Case Studies: Umbilical cord blood (UCB) transplantation is a therapeutic option for several hematological, genetic and metabolic diseases. UCB has a diverse cellular profile and can be considered starting material for advanced cell therapy products, has low immunogenicity and does not require a stringent human leukocyte antigen (HLA) matching. UCB are a promising source of mature Natural Killer (NK) cells and precursors and is easily accessible compared to other sources. Studies under development evaluate the use of NK cells, which are innate lymphocytes recognized for their important role against tumor cells. The quantification of NK cells in UCB is not regularly performed in the product qualification routine, but their quantification may allow the advancement of cell therapies based on NK infusion. The main goal of this study was to obtain the composition of CD34, NK and mononuclear cells in UCB samples, evaluating possible correlations between birth characteristics, maternal serology and cell types present in the samples.

Study

Design/Methods:

This is a retrospective study using data collected from 1272 cord blood samples from a private UBC bank (Cryopraxis Cryobiology) over a 2-year period (2020 – 2022). The percentage of viable mononuclear and CD34+ cells were quantified by flow cytometry (ISHAGE) using the 7AAD dye. NK cell quantification was performed by flow cytometry according to the ISHAGE method, using the CD16 and CD56 markers. Serology was performed by chemiluminescence (anti-HBC, HBsAg, Anti-HCV, Anti-HTLV I/II, Anti-HIV I/II, cytomegalovirus, toxoplasmosis and chagas disease), VDRL for syphilis and NAT for HBV, HVC and HIV.

Results/Findings:

The analysis of the 1272 cord blood samples showed that the average volume collected was 79.4 mL. The percentage of mononuclear cells was 84.7%±6.6 and of viable CD34+ cells was 0.27%±0.12, while the average percentage of NK cells was 13.89%±8,00 (ranging from 57,4% - 1,4%). The final cord blood recovery was 88.71%±4.36, on average. The percentage of non-reactive/negative serology/NAT was of 98,66%, while 1,34% presented reactive/positive or indetrminate results for any of the serology/NAT markers.

Conclusions:

The collection and storage of umbilical cord blood still offers therapeutic advantages, in addition to may be considered starting material for advanced cell therapy. Thus, immunotherapy based on cord blood derived NK cells is promising. The cord blood contains populations of NK cells present in small numbers in peripheral blood. However, cord blood with significant number of NK cells are also observed. Finally, the quantification of those cells in cord blood must be considered as an additional quality control test of the material, since its median profile is variable, but in several cases this number is significant and can be used as starting material for advanced therapies.