Expression of CD34-positive progenitors in fetal human liver hematopoiesis

Objective: In humans, the liver represents the major hematopoietic organ during gestation, as it provides circulating blood cells to the developing fetus. Given this fundamental function, we investigated the presence of liver hematopoietic stem cells at different weeks of gestation. Method: Liver tissue specimens, obtained from ten fetuses with a gestational age ranging from 10 to 36 weeks, were stained with H&E and immunostained with an anti-CD34 monoclonal antibody. The hematopoietic activity was evaluated according to previous works (1) and the presence of CD34+ cells. Results: Hematopoietic activity ranged from stage II and III in earlier weeks of gestation, to stage IV in the latest weeks before birth. In all liver specimens, isolated and scattered CD34+ cells in the hepatic parenchyma in close contact with developing hepatoblasts were identified. Conclusion: The presence of CD34+ progenitors cells in the human fetal liver during gestation, most likely represent hematopoietic stem cells. The finding of CD34+ cells confirms previous data suggesting that hematopoietic stem/progenitor cells could migrate to the liver during the early phases of embryonic development (1). Further studies on a large series of fetal liver might clarify the role of CD34+ stem/progenitors in liver hematopoiesis during fetal life and could provide new insights on the role of hematopoietic precursor cells in pathological conditions. REFERENCES 1. Fanni D, Angotzi F, Lai F, Gerosa C, Senes G, Fanos V, Faa G (2017) Four stages of hepatic hematopoiesis in human embryos and fetuses. The Journal of Maternal-Fetal & Neonatal Medicine 1–7.