The processing of human bone marrow for cryopreservation and reinfusion.

Bone marrow was aspirated from 22 patients with solid tumors. A median of 1.2 x 10(10) net bone marrow cells were obtained during a 1 hour 45 minute operative procedure. Three methods were used to concentrate the bone marrow for cryopreservation. The greatest concentration of mononuclear cells was obtained by the Haemonetics pheresis procedure. Bone marrow was cryopreserved in 10 % DMSO in volumes ranging from 150 to 700 ml. The thawed marrow was further processed to remove both DMSO and free hemoglobin prior to reinfusion. Cell clumping was observed in the first 6 of the 10 marrows thawed. Acidification of the thawed marrow to pH 6.65 was found to retard cell clumping. The immediate recovery of cells frozen was 66 % with a viability of 50 %. The mean number of viable mononuclear bone marrow cells per kilogram available for reinfusion was therefore 5.5 x 10(7).