Use of IL3 and chromatin-modifying reagents valproic acid and 5-aza-2′-deoxycytidine to affect mobilized peripheral blood CD34+ cell fate decisions.

Background and Objectives Culture of blood CD34⁺ cells with chromatin-modifying agents can lead to an increase in marrow repopulating cells and in the case of valproic acid increased erythroid cell colony formation. We undertook research to help understand what effects these reagents have on mobilized peripheral blood ( MPB) CD34⁺ cells. Materials and Methods Mobilized peripheral blood was obtained under informed consent and ethics committee approval from nine patients and allograft donors. Epigenetic modifiers valproic acid and 5-aza-2′-deoxycytidine were used singly or in combination with each other and with IL3 when culturing mobilized peripheral blood CD34⁺ cells. Cultured cells were subsequently used in flow cytometry and colony-forming unit assay experiments. Results Addition of IL3 to the in vitro cell growth medium improved the expansion and maintained the functionality of CD34⁺ cells. Valproic acid and IL3 also work synergistically to increase the numbers of CD34⁺/ CD36⁺ double-positive cells. We found that an apparent increase in red cell colony formation was a result of a decrease in white cell colonies, with no overall increase in red cell colonies when equivalent numbers of CD34⁺ cells are plated. Conclusions Mobilized peripheral blood CD34⁺ stem and progenitor cells are affected by chromatin-modifying agents and IL3 giving higher numbers of CD34⁺/ CD36⁺ double-positive erythroid progenitors. [ABSTRACT FROM AUTHOR]