Ability of Early Acting Cytokines to Directly Promote Survival and Suppress Apoptosis of Human Primitive CD34+CD38− Bone Marrow Cells With Multilineage Potential at the Single-Cell Level: Key Role of Thrombopoietin

Abstract

Purified primitive progenitor/stem cells from bone marrowlonged culture, maintaining twofold and fourfold more prorepresent likely target populations for ex vivo expansion of genitors viable than KL and IL-3, respectively. A high fraction stem cells to be used in high-dose chemotherapy or gene of these progenitors had a combined myeloid and erythroid therapy. Whereas such primitive progenitor cells require differentiation potential, as well as capacity for prolonged combined stimulation by multiple cytokines for growth, production of progenitor cells under stroma-independent some cytokines selectively promote viability rather than conditions. In addition, Tpo promoted viability of growth when acting individually. We investigated here for CD34 " CD38 Ï long-term culture-initiating cells, further supthe first time the direct effects of cytokines on survival of porting the idea that Tpo promotes viability of primitive huprimitive CD34 " CD38 Ï human bone marrow progenitor cells man progenitor cells. Finally, Tpo suppressed apoptosis of at the single-cell level. Interleukin-3 (IL-3) and the ligands CD34 " CD38 Ï cells in culture. Thus, the present studies show for c-kit (KL) and flt3 (FL) had direct and selective viabilitya novel effect of Tpo, implicating a potential role of this promoting effects on a small fraction of CD34 " CD38 Ï but cytokine in maintaining quiescent primitive human progeninot CD34 " CD38 " progenitor cells. Interestingly, the recently tor cells viable. cloned thrombopoietin (Tpo), although stimulating little ᭧ 1997 by The American Society of Hematology. growth, kept most CD34 " CD38 Ï progenitors viable after proinvestigated at the single-cell level, thus allowing limited From the Blood Cell Growth Factors Laboratory, Hipple Cancer of the CD34 / CD38 0 BM progenitor cell population when to what degree individual cytokines might maintain these Sweden.progenitor cells viable. Multiple previous studies have suggested that KL is aDanielssons research trust, and the Kamprad Crafoord and Tobias potent and by far the most efficient viability factor for primi-Foundations. tive murine progenitor cells, including pluripotent long-termAddress reprint requests to Ole J. Borge, MSc, Stem Cell Laborareconstituting stem cells, and that it can maintain the majority of such progenitor cells viable after prolonged culture. [11][12][13] Sweden. In contrast, studies of human CD34 / DR 0 BM progenitor The publication costs of this article were defrayed in part by page cells as well as CD34 / CD38 0 fetal liver cells have reported charge payment. This article must therefore be hereby marked more variable and less extensive effects on viability by KL. [15][16][17] ''advertisement'' in accordance with 18 U.S.C. section 1734 solely to This could be a consequence of culture conditions either not indicate this fact.being optimized for allowing cytokine-induced survival of ᭧ 1997 by The American Society of Hematology. 0006-4971/97/9006-0011$3.00/0 human progenitor cells or could alternatively implicate that

A combination of megakaryocyte growth and development factor and interleukin‐1 is sufficient to culture large numbers of megakaryocytic progenitors and megakaryocytes for transfusion purposes

“…The effects of IL-1 on platelet production could be partly indirect by its stimulating role in the formation of other cytokines. IL-1-induced production of IL-6 has been described both in humans (Brach et al, 1990;Jiang et al, 1994) and in mice (Kimura et al, 1990;Dan et al, 1995). In our culture system IL-6 production was observed if cells were cultured with PEGrHuMGDF and IL-1 (data not shown); this is in agreement with other papers in which IL-6 production by megakaryocytes was described (Jiang et al, 1994;Wickenhauser et al, 1995).…”

“…In contrast, no proliferation but only megakaryocyte differentiation was observed in cultures in the presence of PEG-rHuMGDF alone (data not shown). Thus, as described by others, PEGrHuMGDF must be combined with other growth factors to achieve the proliferation of megakaryocytes (Gehling et al, 1997;Guerriero et al, 1995;Choi et al, 1996;Birkmann et al, 1997;Borge, et al, 1997;Dolzhanskiy et al, 1997;Debili et al, 1995). In our culture system, IL-1 was found to induce the highest proliferation in combination with PEG-rHuMGDF.…”

Production of large numbers of Langerhans' cells with intraepithelial migration ability in vitro

“…SCF and Flt3L have been reported to potently synergize with GM-CSF and TNF-a to promote the expansion of DCs from human peripheral blood hematopoietic progenitors (33,(41)(42)(43) as well as from bone marrow or cord blood progenitors (37,(44)(45)(46)(47). Previous studies also showed that TPO acts not only on human megakaryocyte progenitors but also on primitive multipotential, erythroid, and myeloid progenitors (48)(49)(50)(51) and facilitates the ex vivo expansion of human bone marrow-and cord blood-derived hematopoietic progenitors in combination with other growth factors (52,53). Although the action of TPO on human mobilized CD34 þ hematopoietic progenitors remains to be elucidated, it is likely that TPO, in combination with SCF and Flt3L, enhances the yield of DCs in cultures stimulated by GM-CSF/ TNF-a plus SCF/Flt3L (54,55).…”

The Reduction of In Vitro Radiation‐Induced Fas‐Related Apoptosis in CD34+Progenitor Cells by SCF, FLT‐3 Ligand, TPO, and IL‐3 in Combination Resulted in CD34+Cell Proliferation and Differentiation

“…For instance, SCF and IL-3 are known to prevent unirradiated hematopoietic progenitors from apoptosis [20][21][22][23]. More recently, TPO has been demonstrated to suppress apoptosis of human quiescent primitive CD34 + /CD38 neg BM cells and FL to induce survival and proliferation of CD34 + /CD38 neg cells (with no effect on more mature CD34 + /CD38 + cells) [24][25][26]. Moreover, RI apoptosis can be mitigated by cytokines.…”