Interleukin-6 and interleukin-11 act synergistically with thrombopoietin and stem cell factor to modulate ex vivo expansion of human CD41+ and CD61+ megakaryocytic cells.
OBJECTIVE
Thrombopoietin (TPO), the ligand for the c-mpl receptor, regulates in vivo platelet production and increases the number of colony-forming unit megakaryocytes (CFU-MK). Other cytokines including interleukin (IL) -3, IL-6, IL-11 and stem cell factor (SCF) can stimulate megakaryopoiesis. The aim of this study was to evaluate the effects of different combinations of cytokines involved in megakaryocytopoiesis on stroma-free liquid cultures of purified human CD34+ cells.


METHODS
Peripheral blood cells were collected after mobilization with granulocyte colony-stimulating factor (G-CSF). Purified CD34+ cells were then cultured with different combinations of TPO, SCF, IL-3, IL-6 and IL-11.


RESULTS
The addition of TPO and SCF alone generated a population positive for the antigens CD41 (5.5+/-2.9%) and CD61 (6. 1+/-2.2%) but induced a low amplification of cell number (8.1+/-0.9 fold expansion). The presence of IL-6 or IL-11 was associated with MK progenitor cell expansion, and up to 7-10% of cultured cells were found to be CD41 and CD61 positive by flow cytometry. Conversely, the addition of IL-3 to this cytokine combination was associated with a prominent expansion of the myeloid lineage (70+/-10% of CD33+ cells) but only 0.9% and 2% of cultured cells were positive for CD61 and CD41 respectively.


CONCLUSIONS
Our study supports the idea that IL-6 and IL-11 play crucial roles in the proliferation of MK progenitors and the use of SCF, TPO, IL-6 and IL-11 for ex vivo expansion of this cell population.
Lazzari
L
L
Milano Cord Blood Bank, Centro Trasfusionale e di Immunologia dei Trapianti, IRCCS Ospedale Maggiore, via Francesco Sforza 35, 20122 Milan, Italy. cbbank@polic.cilea.it.
Henschler
R
R
Lecchi
L
L
Rebulla
P
P
Mertelsmann
R
R
Sirchia
G
G
D015703:Antigens, CD / Q000096:biosynthesis / Q000187:drug effects*; D018952:Antigens, CD34 / Q000097:blood / Q000187:drug effects; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001781:Blood Component Removal; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects*; D004357:Drug Synergism; D006801:Humans; D039661:Integrin beta3; D017370:Interleukin-11 / Q000494:pharmacology* / Q000502:physiology; D007377:Interleukin-3 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology* / Q000502:physiology; D008533:Megakaryocytes / Q000187:drug effects* / Q000276:immunology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000096:biosynthesis / Q000187:drug effects*; D010980:Platelet Membrane Glycoproteins / Q000096:biosynthesis / Q000187:drug effects*; D019089:Stem Cell Factor / Q000494:pharmacology* / Q000502:physiology; D013926:Thrombopoietin / Q000494:pharmacology* / Q000502:physiology; D019172:Transplantation Conditioning; D014182:Transplantation, Autologous
D015703:Antigens, CD; D018952:Antigens, CD34; D000970:Antineoplastic Agents; D039661:Integrin beta3; D017370:Interleukin-11; D007377:Interleukin-3; D015850:Interleukin-6; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D010980:Platelet Membrane Glycoproteins; D019089:Stem Cell Factor; D013926:Thrombopoietin