Evaluation of migratory and phagocytic properties of monocyte-derived dendritic cells from human umbilical cord blood

Background

Umbilical cord blood (UCB) represents a unique source for stem cell transplantation while also harboring professional antigen-presenting cells such as monocytes. These may serve as a future source for monocyte-derived dendritic cells (MoDC) for clinical studies, yet the immunological properties of UCB-MoDC are still mostly unknown. This project aims to compare the functional properties of adult- and UCB-MoDC in terms of their migratory and phagocytic behavior.

Methods

Monocytes from adult healthy donors and UCB were magnetically enriched from PBMCs followed by their differentiation and maturation into MoDC. To assess endocytosis and pinocytosis, differentiated MoDC were exposed to FITC-Albumin and TITC-Dextran for 1 hour. Antigen uptake was evaluated by flow cytometry. Control groups were primed with respective inhibitors prior to antigen exposure. Migratory behavior was evaluated in the presence or absence of chemokines (MIP-3β, MIP-1α, SDF-1β). Maturated adult- and UCB-MoDC were added to 8µm transwell inserts, placed into well plates containing media with chemokines and incubated for 90 minutes at 37°C. Migrated MoDC were thereafter enumerated using a flow cytometer.

Results

UCB-MoDC presented macrophage mannose receptor (MMR)-mediated endocytosis of FITC-Dextran in comparison to controls, similar to adult MoDC in a concentration-dependent manner. UCB-MoDC sensitivity to MMR-blocking was similar to adult MoDC. Likewise, macropinocytosis-driven uptake of TITC-Albumin was unaltered in UCB-MoDC in comparison to their adult counterpart. Receptiveness to imipramine, an inhibitor of membrane ruffle formation, was similar between UCB- and adult MoDC. UCB-MoDC presented slightly elevated rates of MIP-3β- and SDF-1β-mediated chemotaxis. However, no significant differences could be detected in comparison to adult MoDC in terms of CCR7 (MIP-3β), CCR5 (MIP-1α) and CXCR4 (SDF-1β)-mediated transmigration.

Conclusion

UCB-derived MoDC present no significant differences compared to APB-derived MoDC in terms of antigen uptake and migratory behavior. These findings have important implications for the evaluation of UCB-MoDC suitability for future clinical applications.

Offenlegung Interessenkonflikt:

The authors declare no conflict of interest.