Thrombopoietin to replace megakaryocyte-derived growth factor: impact on stem and progenitor cells during ex vivo expansion of CD34+ cells mobilized in peripheral blood.
BACKGROUND
The first protocol of ex vivo expansion that enabled almost total abrogation of postmyeloablative chemotherapy neutropenia was based on a three-cytokine cocktail (stem cell factor [SCF], granulocyte-colony-stimulating factor [G-CSF], pegylated-megakaryocyte growth and development factor [PEG-MGDF]) in a serum-free medium. Since the clinical-grade molecule MGDF is no longer available on the market, we evaluated its substitution by thrombopoietin (TPO).


METHODS
CD34+ cells of myeloma patients were expanded for 10 days in serum-free cultures with SCF, G-CSF, or MGDF (100 ng/mL) or with TPO (2.5, 10, 20, 50, and 100 ng/mL) instead of MGDF. Day 10 amplifications of total nucleated cells, CD34+ cells, committed progenitors (CFCs), the capacity of engraftment of NOD/SCID mice (SCID repopulating cells [SRCs]), and the immunophenotype of cells in expansion product (CD13, CD14, CD33, CD41, CD61) were analyzed.


RESULTS
TPO in doses of 2.5 and 10 ng/mL exhibits an effect comparable to that of MGDF (100 ng/mL) on total, CD34+, and CFCs amplification. Compared to MGDF, TPO (starting at 10 ng/mL) enhances two- to threefold the percentage of megakaryocyte lineage cells (CD41+ and CD61+). Finally, TPO maintains or even enhances (depending on dose) SRC activity.


CONCLUSIONS
The use of TPO instead of MGDF in our protocol is feasible without any negative effect on progenitor cell expansion. Furthermore, applied in dose of 10 or 100 ng/mL it could enhance both the stem cell activity and the percentage of megakaryocyte lineage cells in expansion product.
Duchez
Pascale
P
Aquitaine-Limousin Branch of French Blood Institute, Bordeaux, France.
Chevaleyre
Jean
J
Vlaski
Marija
M
Dazey
Bernard
B
Bijou
Fontanet
F
Lafarge
Xavier
X
Milpied
Noël
N
Boiron
Jean-Michel
JM
Ivanovic
Zoran
Z
D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis; D002455:Cell Division; D002478:Cells, Cultured / Q000187:drug effects; D016895:Culture Media, Serum-Free; D006085:Graft Survival; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D019650:Hematopoietic Stem Cell Mobilization; D006412:Hematopoietic Stem Cells / Q000737:chemistry / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D016130:Immunophenotyping; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009101:Multiple Myeloma / Q000097:blood*; D011092:Polyethylene Glycols / Q000494:pharmacology*; D019089:Stem Cell Factor / Q000494:pharmacology; D013926:Thrombopoietin / Q000494:pharmacology*; D014183:Transplantation, Heterologous
D018952:Antigens, CD34; D016895:Culture Media, Serum-Free; D019089:Stem Cell Factor; D016179:Granulocyte Colony-Stimulating Factor; D011092:Polyethylene Glycols; D013926:Thrombopoietin