Hematopoietic peripheral circulating blood stem cells as an independent marker of good transfusion management in patients with β-thalassemia: results from a preliminary study.

BACKGROUND: Beyond hemoglobin (Hb) levels and performance status, further surrogate markers of appropriate transfusion management should improve the quality of thalassemia care. We investigated the levels of peripheral circulating CD34+ stem cells as an independent marker of appropriate hematopoietic balance in patients with thalassemia.

STUDY DESIGN AND METHODS: Peripheral circulating CD34+ stem cells, colony-forming unitgranulocyte, erythrocyte, macrophage, magakaryocyte (CF-GEMM), colony-forming unitgranulocyte/macrophage (CFU-GM), and erythroidburst-forming units (BFU-E) were assayed, according to standard procedures. Patients with thalassemia major (TM) and thalassemia intermedia (TI) were tested and compared to healthy controls. Demographic and clinical data were recorded.

RESULTS: Overall, 56 patients with TM (median age, 35 years; range, 13-52 years) and 13 with TI (median age, 44 years; range, 27-67 years) were evaluated. Annual red blood cell (RBC) transfusion requirements ranged from 10 to 65 units in all patients except four nontransfused cases. A significant increase in peripheral circulating stem cells was observed in patients, in comparison with healthy controls. Nontransfused patients showed the mean highest levels of stem cells (CD34, 32.5 ± 14.8/μL; BFU-E, 41.3 ± 22.8/mL; CFU-GM, 19.6 ± 5.6/mL; CFU-GEMM, 9.0 ± 6.1/mL). CD34+ cell count was 6.9 ± 4.5/μL in TM (p = 0.014) and 11.8 ± 14.8/μL (p = 0.051) in TI. Furthermore, only in patients with TI was a significant increase in CFU-GEMM (3.0 ± 4.8 vs. 0.75 ± 2.05/mL, p = 0.0001) observed. At multivariate analysis, peripheral circulating CD34+ stem cells did not correlate with age, sex, smoking habit, number of RBCs units transfused, Hb levels, iron chelation therapy, history of splenectomy, and hypothyroidism.

CONCLUSION: Circulating peripheral CD34 + stem cells are increased in β-thalassemia, in particular in nontransfused patients, compared to healthy controls.