Figure 7

Valproic acid modifies short-term engraftment but does not influence long-term engraftment and differentiation capacity of VPA expanded CD34⁺ cells. (a) Schematic representation of the engraftment assay performed in NSG mice. Sub-lethally irradiated (100 cGy) mice were intravenously transplanted with 3.5 × 10⁵ CD34⁺ VPA-treated or control cells. Engraftment of human CD34⁺ cells was monitored by analyzing chimerism and phenotype of circulating human leucocytes (human CD45⁺) in the peripheral blood of recipient mice every four weeks by flow cytometry. Long-term in vivo marrow repopulation capacity was determined at 20 weeks after transplantation by quantification and phenotyping of human leucocytes in the femur of NSG mice (n = 5 per group). (b) Overall peripheral blood chimerism increased by week 12 and subsequently declined. Mice transplanted with PBS-treated CD34⁺ cells showed elevated overall chimerism compared to mice that received VPA-treated CD34⁺ cells. Differences were most pronounced at week 8 but did not reach statistical significance (p = 0.913). Data represent mean + SD. (c) Lineage commitment of circulating human leucocytes was examined by analyzing CD3, CD19, and CD33 cell surface expression with no significant differences in the proportion of T-cells, B-cells or myeloid cells. (d) Absolute numbers of human leucocytes (human CD45⁺) per femur at week 20 after transplantation did not differ between groups (p = 0.61). (e) Lineage diversification of long-term marrow repopulating human leucocytes was similar in mice injected with VPA-treated or PBS-treated human CD34⁺ cells at 20 weeks after transplantation.