ORIGINAL ARTICLE The pharmacological activation of adenosine A 1 and A 3 receptors does not modulate the long- or short-term repopulating ability of hematopoietic stem and multipotent progenitor cells in mice Michal Hofer & Milan Pospíšil & Zuzana Hoferová & Denisa Komůrková & Petr Páral & Filipp Savvulidi & Luděk Šefc Received: 13 September 2012 / Accepted: 6 November 2012 / Published online: 15 December 2012 # Springer Science+Business Media Dordrecht 2012 Abstract This study continues our earlier findings on the hematopoiesis-modulating effects of adenosine A 1 and A 3 receptor agonists that were performed on committed hemato- poietic progenitor and precursor cell populations. In the earlier experiments, N 6 -cyclopentyladenosine (CPA), an adenosine A 1 receptor agonist, was found to inhibit proliferation in the above-mentioned hematopoietic cell systems, whereas N 6 -(3- iodobenzyl)adenosine-5′-N-methyluronamide (IB-MECA), an adenosine A 3 receptor agonist, was found to stimulate it. The topic of this study was to evaluate the possibility that the above-mentioned adenosine receptor agonists modulate the behavior of early hematopoietic progenitor cells and hemato- poietic stem cells. Flow cytometric analysis of hematopoietic stem cells in mice was employed, as well as a functional test of hematopoietic stem and progenitor cells (HSPCs). These tech- niques enabled us to study the effect of the agonists on both short-term repopulating ability and long-term repopulating ability, representing multipotent progenitors and hematopoi- etic stem cells, respectively. In a series of studies, we did not find any significant effect of adenosine agonists on HSPCs in terms of their numbers, proliferation, or functional activity. Thus, it can be concluded that CPA and IB-MECA do not significantly influence the primitive hematopoietic stem and progenitor cell pool and that the hematopoiesis-modulating action of these adenosine receptor agonists is restricted to more mature compartments of hematopoietic progenitor and precursor cells. Keywords Adenosine receptor agonists . CPA . IB-MECA . Hematopoietic stem cells . Long-term repopulating ability Introduction Hematopoiesis is under the control of numerous regulatory factors which act at various levels of the hematopoietic cell hierarchy, including stem, progenitor and precursor cells, as well as differentiated functional peripheral blood cells [1]. Adenosine, a ubiquitous purine nucleoside released into the extracellular environment from metabolically active or stressed cells, acts as paracrine regulator of many cellular functions, including those of cell proliferation and differen- tiation [2–5]. The regulatory role of extracellular adenosine is based on the activation of cell surface receptors, denoted as A 1 ,A 2a ,A 2b , and A 3 . Receptor activation can be achieved either nonselectively by adenosine or selectively using var- ious adenosine analogs [6, 7]. The system of adenosine receptors and their agonists has been shown to play a distinct regulatory role in the processes of cell proliferation and differentiation in normal, as well as suppressed hematopoiesis [for a review, see 8, 9]. Numerous Electronic supplementary material The online version of this article (doi:10.1007/s11302-012-9340-5) contains supplementary material, which is available to authorized users. M. Hofer : M. Pospíšil : Z. Hoferová : D. Komůrková Laboratory of Experimental Hematology, Institute of Biophysics, v.v.i, Academy of Sciences of the Czech Republic, Královopolská 135, 61265 Brno, Czech Republic P. Páral : F. Savvulidi : L. Šefc (*) Institute of Pathological Physiology, First Faculty of Medicine, Charles University in Prague, U Nemocnice 5, 128 53 Praha 2, Czech Republic e-mail: sefc@cesnet.cz Purinergic Signalling (2013) 9:207–214 DOI 10.1007/s11302-012-9340-5