Ex Vivo Expansion of Hematopoietic Progenitors from CD34+ Cells Selected from Leukapheresis Products of Lymphoma and Myeloma Patients: Feasibility and Enhancement by Fibronectin

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Abstract
The feasibility of ex vivo expansion of hematopoietic progenitors selected from leukapheresis products of patients treated for multiple myeloma (MM) was studied and compared with progenitor expansions from patients with nodular non-Hodgkin's lymphoma (NHL) or healthy donors. After positive selection, CD34+ cells from leukapheresis products of 4 MM and 5 NHL patients and CD34+ cells from bone marrow (BM) of 3 healthy donors were grown in IMDM plus 12.5% horse serum, 12.5% fetal calf serum, IL-1α, IL-3, IL-6, SCF, GM-CSF, G-CSF (10 ng/ml each), and EP (4 UI/ml). Outputs of CD34+ cell cultures from MM and NHL patients were similar. Day 14 mean increases in CD34+, CFU-GM, and total cell numbers were, respectively, 5.3-fold, 19.8-fold, and 1173-fold for MM patients and 4.3-fold, 15.6-fold, and 1659-fold for NHL patients, with at least 40% of day 14 cells being of granulocytic lineage. Patient CD34+ cell culture output was found to be related to the CFU-GM/CD34+ cell ratio of selected CD34+ cells, not to underlying pathology. When the initial CFU-GM/CD34+ cell ratio was above 0.025, MM and NHL CD34+ cell culture outputs were always above 1000-fold. Moreover, in all but one CD34+ cell culture, the use of fibronectin (FN)-coated dishes improved CFU-GM and total cell expansion. In patient CD34+ cultures carried out in FN-coated dishes, mean day 14 CFU-GM and total cell outputs were increased, respectively, 2.1-fold and 1.9-fold. We conclude that if the CFU-GM/CD34+ cell ratio is sufficient (>0.025), ex vivo expansion of hematopoietic progenitors from CD34+ cells selected from leukapheresis products is possible for both MM and NHL patients and that using FN-coated flasks is a simple and reliable way to improve both CFU-GM and total cell output.