Co-culture of human hematopoietic stem cells with osteoblasts affects mono/macrophage versus erythroid lineage choice.

Hematopoietic stem cells (HSCs) are located in the bone marrow in a specific microenvironment referred as the hematopoietic stem cell niche, where HSCs interact with a variety of stromal cells. Though several components of the stem cell niche have been identified, the regulatory mechanisms through which such components regulate the stem cell fate are still unknown. In order to address this issue, we investigated how osteoblasts (OBs) can affect the molecular and functional phenotype of HSCs and vice versa. Our data showed that CD34+ cells cultured with OBs give rise to higher total cell numbers, produce more CFU and maintain a higher percentage of CD34+CD38- cells compared to control culture. Moreover, clonogenic assay and long-term culture results showed that OBs enhance HSC differentiation towards the mono/macrophage lineage at the expense of the granulocytic and erythroid ones. Finally, GEP analysis allowed us to identify several cytokine-receptor networks, such as WNT pathway, and transcription factors, as TWIST1 and FOXC1, that could be activated by co-culture with OBs and could be responsible for the biological effects reported above.

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Salati S, Lisignoli G, Manferdini C, Pennucci V, Zini R, Bianchi E, Norfo R, Facchini A, Ferrari S, Manfredini R