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. 2018 Jun 12;2(4):e51. doi: 10.1097/HS9.0000000000000051

Figure 1.

Figure 1

Ex vivo induction of iMLL-ENL provides aberrant self-renewal and blocks differentiation of HSPCs in a fully reversible manner. (A) MLL-ENL expression is controlled by a Tet-responsive element (TRE). The reverse tetracycline transactivator (rtTA) cassette was integrated into the Rosa26 locus and the MLL-ENL fusion gene was targeted into the Hprt locus. (B) Proliferation of iMLL-ENL BM cells grown in liquid cultures with growth factors (10 ng/mL of IL-3, IL-6, and IL-7, 100 ng/mL of SCF and Flt3L) in presence (red) of absence (green) of DOX (1 μg/mL) for up to 25 days. (C) Quantification of colony types formed in the 1st replate in the presence or absence of DOX. (D) Reversibility of transformation, loss of immature compact colony formation capacity, and differentiation of blasts into mature macrophage/monocyte like cells upon removal of DOX as shown by the representative MC cultures. (E) Expression of iMLL-ENL mRNA in ex vivo cultured BM cells exposed to increasing amounts of DOX compared with cells immortalized by retroviral MLL-ENL expression, as assessed by quantitative (TaqMan) RT-PCR analysis. (F) Number of colonies of serial replatings of iMLL-ENL BM cells in growth factor-containing MC with and without DOX, and upon DOX removal. BM = bone marrow, DOX = doxycycline, MC = methylcellulose.