24th Congress of the European Hematology Association, Amsterdam, Netherlands, 13 - 16 June 2019, vol.3, pp.1038
Vitamin D is a steroid hormone which has an essential role in many physiological conditions including bone metabolism, immune regulation and hematopoiesis. Vitamin D was indicated to have a favourable impact on hematopoietic stem cell (HSC) production in in-vitro studies. Additionally, animal experiments designated a potential for vitamin D receptor in HSC mobilization. Despite these advances, the possible role of vitamin D in peripheral HSC mobilization remains to be defined.
The aim of this study was to evaluate the impact of pre-mobilization serum vitamin D levels on peripheral HSC mobilization in allogeneic donors.
We investigated the impact of pre-mobilization serum vitamin D levels of 112 allogeneic donors [median age: 39(18-69) years; male/female: 62/50] on peripheral HSC mobilization. All donors had received granulocyte colony stimulating factor (G-CSF) at a dose of 10 mcg/kg/day for 4 days. First HSC apheresis was performed on the fourth day of G-CSF. Serum 25-hydroxy vitamin D levels were measured with immunoassay method before G-CSF administration.
Median vitamin D level was found to be 15.8(3-63.2) μg/L in the study population. On the first apheresis day, median peripheral and product CD34(+) cell counts were 36.5(7-206) × 106/kg and 5.3(0.5-22.8) × 106/kg respectively. Median vitamin D levels were significantly lower in donors with low peripheral CD34(+) cell count which was defined as <20 × 106/kg, compared to donors with CD34 level≥20 × 106/kg [13.5(7-27.4) μg/L vs 17(3-63.2) μg/L; p = 0.035] (Figure 1). When we divide the study group into two subgroups based on median vitamin D levels, peripheral CD34(+) cell counts were found to be significantly lower in low-vitamin D group compared to high-vitamin D group [35(7-135) × 106 vs 41.4(10-206) × 106; p = 0.038]. Any significant association was not observed between vitamin D levels and product CD34(+) cell counts. In logistic regression analysis, serum vitamin D level was considered to be correlated with peripheral CD34(+) cell count [p = 0.042; SE: 0.034; 95% Cl Exp(B): 1.003-1.145].
Mobilization failure still remains to be a critical issue for HSC transplantation. In this study, the significant association between vitamin D levels and peripheral CD34(+) cell counts, lacking a similar correlation with product CD34(+) cell counts, requires further evaluation with larger study populations and more standardized procedures including product processing and collection. In these circumstances, the possible role of vitamin D in HSC mobilization deserves further consideration as vitamin D replacement before mobilization would be an easy, safe and cost-effective approach to improve mobilization success.