Jean-Rémy Van Cauwenberge

Circadian and circannual variations in cord blood hematopoietic cell composition

Several previous studies have demonstrated that cord blood unit composition is an important factor that may predict outcomes after cord blood transplantation, with higher doses of transplanted nucleated cells and hematopoietic stem and progenitor cells being associated with faster engraftment and better overall survival. In the setting of this study involving 3 University centers, we analyzed factors potentially influencing cord blood cell composition. In accordance with the results of several previous publications, we observed that gestational age, birth weight and babys gender impacted concentrations of nucleated and hematopoietic progenitor cells in cord blood. We also showed that uses of epidural anesthesia and of oxytocin were associated with higher concentrations of hematopoietic progenitor cells. Interestingly, we observed that nucleated cell and progenitor cell concentrations were also determined by time of day and month of delivery. Recent studies have suggested chronological rhythmic egress of hematopoietic stem and progenitor cells from the bone marrow to the peripheral blood in adult individuals. Our findings suggest that such physiological rhythm may not be restricted to post-natal life. We think our study may have practical implications for cord blood banking strategies and also raises questions about chronological rhythm in hematopoietic cell trafficking during fetal life.