Clinical Scale Expansion of Cryopreserved Small Volume Whole Bone Marrow Aspirates Produces Sufficient Cells for Clinical Use

Abstract

Ex vivo expansion of bone marrow (BM) mononuclear cells (MNC) in a perfused culture system produces stem-progenitor cell type(s) in sufficient number(s) for hematopoietic reconstitution. The limitations in using fresh BM MNC for ex vivo expansion include additional cell processing and inflexibility in patient treatment. Cryopreservation of whole bone marrow (WBM) eliminates processing costs of MNC or CD34+ cell selection and allows for flexibility in patient treatment. We developed a convenient system to cryopreserve and thaw small volume WBM aspirations (n = 13) and then compared the expandability of unprocessed normal cryopreserved/thawed (C/T) WBM to that of fresh BM MNC cultured in the presence of erythropoietin, PIXY 321, and Flt3-ligand. Ex vivo expansion potential was retained in WBM aspirates after C/T. When initiated with 225 million viable nucleated cells, clinical scale expansion cultures (n = 6) yielded 9.7 +/- 2.8 X 10 8 total cells, which contained 10.4 +/- 5.8 X 10 6 colony-forming units-granulocyte-macrophage(CFU-GM), 1.3 +/- 1.4 X 10 4 LTCIC, and 2.2 X 10 6 CD34+Lin- cells, sufficient cell numbers for clinical use. These studies demonstrate that ex vivo perfusion culture expansion of unfractionated C/T WBM( 30 ml) provides doses of stem-progenitor cells similar in composition to expanded fresh BM MNC, previously demonstrated to achieve hematopoietic reconstitution.