Background

Umbilical cord blood (UCB) describes a valuable resource of stem cells for pediatric and ethnic minority stem cell transplantations. Monocytes, as part of the innate immune system, are able to generate dendritic cells (MoDC), and thus play an important role in T-cell activation and cellular therapies. However, UCB-MoDC have not been extensively characterized in previous studies. This study aims to characterize the phenotype of UCB-MoDC to assess possible applications in cellular therapies.

Methods

In order to characterize UCB-derived monocytes and MoDC, CD14⁺ monocytes were magnetically isolated from healthy adult donors and UCB-derived PBMC (purity >95%), differentiated with IL-4 and GM-CSF for 5 days followed by their maturation (IL-1β, IL-6, TNFα, IFNγ, PGE₂) for additional 2 days. Characterization and survey of monocyte and MoDC viability and surface marker expression for activation, migration and differentiation were analyzed on d0, d5 and d7 by flow cytometry.

Results

Freshly isolated UCB CD14⁺ monocytes displayed significantly lower frequencies in CD11c, HLA-DP,DQ,DR, and Fas-L expression in comparison to adult CD14⁺ monocytes. Comparison between adult and UCB-MoDC cultures revealed no significant differences in vitality and cell recovery. Expression of key MoDC markers such as CD209 and CD40 were similar between adult and UCB-MoDC. However, UCB-MoDC displayed significantly lower frequencies for CD11c and CD80 expression while expression levels were significantly reduced for CD11c, CD83, CD274 (PD-L1) and CCR7 in comparison to adult MoDC cultures. Simultaneously, frequencies of CD14 and CD16 expressing UCB-MoDC were significantly greater than in adult MoDC cultures.

Conclusion

UCB provide a viable source of monocytes for the generation of MoDC. Further investigations will clarify if the observed differences in co-stimulator and chemokine receptor expression translates to functional differences in comparison to adult MoDC in order to evaluate their potential for potential future clinical applications.

Offenlegung Interessenkonflikt:

The authors have no conflict of interests to declare.