Association of Circulating CD34+ Cell Count with Liver Conditions.

Hematopoietic stem and progenitor cells, which express CD34 antigen, circulate at a very low frequency in peripheral blood in steady state. CD34+ cells are highly mobilized after myeloablative chemotherapy or the administration of various cytokines such as granulocyte colony-stimulating factor and thrombopoietin (TPO). As TPO is mainly produced by the liver, liver conditions may be associated with hematopoiesis, especially thrombopoiesis. In fact, thrombocytopenia is common in patients with chronic liver diseases. To clarify the association of CD34+ cell mobilization with liver conditions, we examined the number of circulating CD34+ cells in 88 patients with various stages of hepatitis C virus-associated chronic liver diseases; 5 healthy carriers, 43 patients with chronic hepatitis (CH), 19 patients with liver cirrhosis (LC), and 21 patients with LC and hepatocellular carcinoma (HCC). Moreover, to assess the basal number of circulating CD34+ cells, 16 healthy controls were included. The evaluation of CD34+ cells has been carried out by flow cytometry, by applying conventional protocols. The number of circulating CD34+ cells was significantly diminished with progression of liver disease: healthy controls, 3.78 ± 3.93 cells/μL; healthy carrier, 1.89 ± 0.94 cells/μL; CH, 1.49 ± 1.41 cells/μL; LC, 0.66 ± 0.83 cells/μL; and LC with HCC, 0.58 ± 0.19 cells/μL. Next, we analyzed platelet count and number of circulating CD34+ cells before and after living donor liver transplantation (LDLT) in 12 patients who underwent LDLT for LC and/or HCC. A 4-fold increase in platelet level (from 68 x 10⁹/L to 234 x 10⁹/L) and a 5-fold increase in number of circulating CD34+ cells (from 0.78 cells/μL to 3.52 cells/μL) were observed after LDLT. These results suggest that not only thrombopoiesis but also mobilization of CD34+ cells from bone marrow into PB depends on liver conditions.