Stromal regulation of hemopoietic stem cells in long-term human bone marrow tissue cultures under the effect of parathyroid hormone

We studied the interaction between different categories of hemopoietic precursors with parathyroid hormone-activated stromal microenvironment. Improved survival of early precursors capable long-term hemopoiesis maintenance and increased number of later short-term repopulating precursors was demonstrated on the model of co-culturing of human bone marrow cells on a layer of adherent cells of long-term bone marrow cultures treated with parathyroid hormone. These changes correlate with increased expression of genes involved in the maintenance of the hemopoietic stem cells in the sublayer activated by parathyroid hormone. Simultaneously, the expression of some stromal differentiation genes, adhesion molecules for hemopoietic stem cells, and growth factors increased in adherent cell layers treated with parathyroid hormone. These findings attest to activating effect of parathyroid hormone on cells forming the niches for both early and later hemopoietic precursors, and hence parathyroid hormone can be used as a potential agent promoting expansion of early hemopoietic stem cells ex vivo. __________ Translated from Kletochnye Tekhnologii v Biologii i Medicine, No. 4, pp. 218–222, December, 2006