Long term maintenance of myeloid leukemic stem cells cultured with unrelated XXXX mesenchymal stromal cells.

@entity1 @entity19 @entity3052 @entity1778 @entity3053 @entity2280
Mesenchymal stromal cells (MSCs) support the growth and differentiation of normal hematopoietic stem cells (HSCs). Here we studied the ability of MSCs to support the growth and survival of leukemic stem cells (LSCs) in vitro. Primary @entity1778 isolated from the peripheral blood of 8 @entity1 with @entity3052 ( @entity3052 ) were co-cultured with equal numbers of irradiated MSCs derived from unrelated donor bone marrow, with or without cytokines for up to 6weeks. Four samples showed @entity2280 (+) @entity3053 (-) predominance, and four were predominantly @entity2280 (+) @entity3053 (+). @entity2280 (+) @entity3053 (-) predominant @entity1778 cells maintained the @entity2280 (+) @entity3053 (-) phenotype and were viable for 6weeks when co-cultured with MSCs compared to co-cultures with cytokines or medium only, which showed rapid differentiation and loss of the LSC phenotype. In contrast, @entity2280 (+) @entity3053 (+) predominant leukemic cells maintained the @entity2280 (+) @entity3053 (+) phenotype when co-cultured with MSCs alone, but no culture conditions supported survival beyond 4weeks. Cell cycle analysis showed that MSCs maintained a higher proportion of @entity2280 (+) blasts in G0 than leukemic cells cultured with cytokines. @entity3052 blasts maintained in culture with MSCs for up to 6weeks engrafted NSG @entity19 with the same efficiency as their non-cultured counterparts, and the original karyotype persisted after co-culture. Chemosensitivity and transwell assays suggest that MSCs provide pro-survival benefits to @entity1778 through cell-cell contact. We conclude that MSCs support long-term maintenance of LSCs in vitro. This simple and inexpensive approach will facilitate basic investigation of LSCs and enable screening of novel therapeutic agents targeting LSCs.
