Bone Marrow Fractionation by the Haemonetics System: Reduction of Red Cell Mass before Marrow Freezing, with Special Reference to Pediatric Marrow Volumes

For purposes of freezing autologous marrow or transplants of allogeneic marrow with major ABO blood group incompatibility, 54 freshly harvested bone marrows from children of 7–65 kg of weight were depleted of their red cells with the Haemonetics V50 system. The marrow volumes ranged from 230 to 1,145 ml, with 17 small (200–399 ml), 18 intermediate (400–799 ml) and 19 large (800–1,200 ml) volumes. After processing, the median recoveries were: volume 24%, red cell mass 18%, and nucleated cells 75%. In the small marrow volume group, a good nucleated cell recovery was achieved at the expense of red cell depletion. The colony‐forming units, granulocytes‐macrophages (CFU‐GM) were normal after thawing of processed, cryopreserved marrows, and good engraftment of both allogeneic and autologous marrows were achieved. We conclude that marrow processing with the Haemonetics V50 system results in adequate red cell depletion and good nucleated cell recovery without open‐air contact of marrow or excessive time consumption. For small marrow volumes, however, the red cell depletion was suboptimal, and a bowl size smaller than 125 ml is desirable for pediatric use.